diff --git a/library/ssl_tls.c b/library/ssl_tls.c
new file mode 100644
index 0000000..abe2450
--- /dev/null
+++ b/library/ssl_tls.c
@@ -0,0 +1,10634 @@
+/*
+ *  SSLv3/TLSv1 shared functions
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+/*
+ *  The SSL 3.0 specification was drafted by Netscape in 1996,
+ *  and became an IETF standard in 1999.
+ *
+ *  http://wp.netscape.com/eng/ssl3/
+ *  http://www.ietf.org/rfc/rfc2246.txt
+ *  http://www.ietf.org/rfc/rfc4346.txt
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_SSL_TLS_C)
+
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdlib.h>
+#define mbedtls_calloc    calloc
+#define mbedtls_free      free
+#endif
+
+#include "mbedtls/debug.h"
+#include "mbedtls/ssl.h"
+#include "mbedtls/ssl_internal.h"
+#include "mbedtls/platform_util.h"
+
+#include <string.h>
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#include "mbedtls/psa_util.h"
+#include "psa/crypto.h"
+#endif
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+#include "mbedtls/oid.h"
+#endif
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#include "mbedtls/psa_util.h"
+#endif
+
+static void ssl_reset_in_out_pointers( mbedtls_ssl_context *ssl );
+static uint32_t ssl_get_hs_total_len( mbedtls_ssl_context const *ssl );
+
+/* Length of the "epoch" field in the record header */
+static inline size_t ssl_ep_len( const mbedtls_ssl_context *ssl )
+{
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        return( 2 );
+#else
+    ((void) ssl);
+#endif
+    return( 0 );
+}
+
+/*
+ * Start a timer.
+ * Passing millisecs = 0 cancels a running timer.
+ */
+static void ssl_set_timer( mbedtls_ssl_context *ssl, uint32_t millisecs )
+{
+    if( ssl->f_set_timer == NULL )
+        return;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "set_timer to %d ms", (int) millisecs ) );
+    ssl->f_set_timer( ssl->p_timer, millisecs / 4, millisecs );
+}
+
+/*
+ * Return -1 is timer is expired, 0 if it isn't.
+ */
+static int ssl_check_timer( mbedtls_ssl_context *ssl )
+{
+    if( ssl->f_get_timer == NULL )
+        return( 0 );
+
+    if( ssl->f_get_timer( ssl->p_timer ) == 2 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "timer expired" ) );
+        return( -1 );
+    }
+
+    return( 0 );
+}
+
+static void ssl_update_out_pointers( mbedtls_ssl_context *ssl,
+                                     mbedtls_ssl_transform *transform );
+static void ssl_update_in_pointers( mbedtls_ssl_context *ssl,
+                                    mbedtls_ssl_transform *transform );
+
+#define SSL_DONT_FORCE_FLUSH 0
+#define SSL_FORCE_FLUSH      1
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+
+/* Forward declarations for functions related to message buffering. */
+static void ssl_buffering_free( mbedtls_ssl_context *ssl );
+static void ssl_buffering_free_slot( mbedtls_ssl_context *ssl,
+                                     uint8_t slot );
+static void ssl_free_buffered_record( mbedtls_ssl_context *ssl );
+static int ssl_load_buffered_message( mbedtls_ssl_context *ssl );
+static int ssl_load_buffered_record( mbedtls_ssl_context *ssl );
+static int ssl_buffer_message( mbedtls_ssl_context *ssl );
+static int ssl_buffer_future_record( mbedtls_ssl_context *ssl );
+static int ssl_next_record_is_in_datagram( mbedtls_ssl_context *ssl );
+
+static size_t ssl_get_current_mtu( const mbedtls_ssl_context *ssl );
+static size_t ssl_get_maximum_datagram_size( mbedtls_ssl_context const *ssl )
+{
+    size_t mtu = ssl_get_current_mtu( ssl );
+
+    if( mtu != 0 && mtu < MBEDTLS_SSL_OUT_BUFFER_LEN )
+        return( mtu );
+
+    return( MBEDTLS_SSL_OUT_BUFFER_LEN );
+}
+
+static int ssl_get_remaining_space_in_datagram( mbedtls_ssl_context const *ssl )
+{
+    size_t const bytes_written = ssl->out_left;
+    size_t const mtu           = ssl_get_maximum_datagram_size( ssl );
+
+    /* Double-check that the write-index hasn't gone
+     * past what we can transmit in a single datagram. */
+    if( bytes_written > mtu )
+    {
+        /* Should never happen... */
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    return( (int) ( mtu - bytes_written ) );
+}
+
+static int ssl_get_remaining_payload_in_datagram( mbedtls_ssl_context const *ssl )
+{
+    int ret;
+    size_t remaining, expansion;
+    size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    const size_t mfl = mbedtls_ssl_get_max_frag_len( ssl );
+
+    if( max_len > mfl )
+        max_len = mfl;
+
+    /* By the standard (RFC 6066 Sect. 4), the MFL extension
+     * only limits the maximum record payload size, so in theory
+     * we would be allowed to pack multiple records of payload size
+     * MFL into a single datagram. However, this would mean that there's
+     * no way to explicitly communicate MTU restrictions to the peer.
+     *
+     * The following reduction of max_len makes sure that we never
+     * write datagrams larger than MFL + Record Expansion Overhead.
+     */
+    if( max_len <= ssl->out_left )
+        return( 0 );
+
+    max_len -= ssl->out_left;
+#endif
+
+    ret = ssl_get_remaining_space_in_datagram( ssl );
+    if( ret < 0 )
+        return( ret );
+    remaining = (size_t) ret;
+
+    ret = mbedtls_ssl_get_record_expansion( ssl );
+    if( ret < 0 )
+        return( ret );
+    expansion = (size_t) ret;
+
+    if( remaining <= expansion )
+        return( 0 );
+
+    remaining -= expansion;
+    if( remaining >= max_len )
+        remaining = max_len;
+
+    return( (int) remaining );
+}
+
+/*
+ * Double the retransmit timeout value, within the allowed range,
+ * returning -1 if the maximum value has already been reached.
+ */
+static int ssl_double_retransmit_timeout( mbedtls_ssl_context *ssl )
+{
+    uint32_t new_timeout;
+
+    if( ssl->handshake->retransmit_timeout >= ssl->conf->hs_timeout_max )
+        return( -1 );
+
+    /* Implement the final paragraph of RFC 6347 section 4.1.1.1
+     * in the following way: after the initial transmission and a first
+     * retransmission, back off to a temporary estimated MTU of 508 bytes.
+     * This value is guaranteed to be deliverable (if not guaranteed to be
+     * delivered) of any compliant IPv4 (and IPv6) network, and should work
+     * on most non-IP stacks too. */
+    if( ssl->handshake->retransmit_timeout != ssl->conf->hs_timeout_min )
+    {
+        ssl->handshake->mtu = 508;
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "mtu autoreduction to %d bytes", ssl->handshake->mtu ) );
+    }
+
+    new_timeout = 2 * ssl->handshake->retransmit_timeout;
+
+    /* Avoid arithmetic overflow and range overflow */
+    if( new_timeout < ssl->handshake->retransmit_timeout ||
+        new_timeout > ssl->conf->hs_timeout_max )
+    {
+        new_timeout = ssl->conf->hs_timeout_max;
+    }
+
+    ssl->handshake->retransmit_timeout = new_timeout;
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %d millisecs",
+                        ssl->handshake->retransmit_timeout ) );
+
+    return( 0 );
+}
+
+static void ssl_reset_retransmit_timeout( mbedtls_ssl_context *ssl )
+{
+    ssl->handshake->retransmit_timeout = ssl->conf->hs_timeout_min;
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %d millisecs",
+                        ssl->handshake->retransmit_timeout ) );
+}
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+/*
+ * Convert max_fragment_length codes to length.
+ * RFC 6066 says:
+ *    enum{
+ *        2^9(1), 2^10(2), 2^11(3), 2^12(4), (255)
+ *    } MaxFragmentLength;
+ * and we add 0 -> extension unused
+ */
+static unsigned int ssl_mfl_code_to_length( int mfl )
+{
+    switch( mfl )
+    {
+    case MBEDTLS_SSL_MAX_FRAG_LEN_NONE:
+        return ( MBEDTLS_TLS_EXT_ADV_CONTENT_LEN );
+    case MBEDTLS_SSL_MAX_FRAG_LEN_512:
+        return 512;
+    case MBEDTLS_SSL_MAX_FRAG_LEN_1024:
+        return 1024;
+    case MBEDTLS_SSL_MAX_FRAG_LEN_2048:
+        return 2048;
+    case MBEDTLS_SSL_MAX_FRAG_LEN_4096:
+        return 4096;
+    default:
+        return ( MBEDTLS_TLS_EXT_ADV_CONTENT_LEN );
+    }
+}
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+int mbedtls_ssl_session_copy( mbedtls_ssl_session *dst,
+                              const mbedtls_ssl_session *src )
+{
+    mbedtls_ssl_session_free( dst );
+    memcpy( dst, src, sizeof( mbedtls_ssl_session ) );
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+
+#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    if( src->peer_cert != NULL )
+    {
+        int ret;
+
+        dst->peer_cert = mbedtls_calloc( 1, sizeof(mbedtls_x509_crt) );
+        if( dst->peer_cert == NULL )
+            return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+
+        mbedtls_x509_crt_init( dst->peer_cert );
+
+        if( ( ret = mbedtls_x509_crt_parse_der( dst->peer_cert, src->peer_cert->raw.p,
+                                        src->peer_cert->raw.len ) ) != 0 )
+        {
+            mbedtls_free( dst->peer_cert );
+            dst->peer_cert = NULL;
+            return( ret );
+        }
+    }
+#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+    if( src->peer_cert_digest != NULL )
+    {
+        dst->peer_cert_digest =
+            mbedtls_calloc( 1, src->peer_cert_digest_len );
+        if( dst->peer_cert_digest == NULL )
+            return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+
+        memcpy( dst->peer_cert_digest, src->peer_cert_digest,
+                src->peer_cert_digest_len );
+        dst->peer_cert_digest_type = src->peer_cert_digest_type;
+        dst->peer_cert_digest_len = src->peer_cert_digest_len;
+    }
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
+    if( src->ticket != NULL )
+    {
+        dst->ticket = mbedtls_calloc( 1, src->ticket_len );
+        if( dst->ticket == NULL )
+            return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+
+        memcpy( dst->ticket, src->ticket, src->ticket_len );
+    }
+#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+int (*mbedtls_ssl_hw_record_init)( mbedtls_ssl_context *ssl,
+                     const unsigned char *key_enc, const unsigned char *key_dec,
+                     size_t keylen,
+                     const unsigned char *iv_enc,  const unsigned char *iv_dec,
+                     size_t ivlen,
+                     const unsigned char *mac_enc, const unsigned char *mac_dec,
+                     size_t maclen ) = NULL;
+int (*mbedtls_ssl_hw_record_activate)( mbedtls_ssl_context *ssl, int direction) = NULL;
+int (*mbedtls_ssl_hw_record_reset)( mbedtls_ssl_context *ssl ) = NULL;
+int (*mbedtls_ssl_hw_record_write)( mbedtls_ssl_context *ssl ) = NULL;
+int (*mbedtls_ssl_hw_record_read)( mbedtls_ssl_context *ssl ) = NULL;
+int (*mbedtls_ssl_hw_record_finish)( mbedtls_ssl_context *ssl ) = NULL;
+#endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
+
+/*
+ * Key material generation
+ */
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+static int ssl3_prf( const unsigned char *secret, size_t slen,
+                     const char *label,
+                     const unsigned char *random, size_t rlen,
+                     unsigned char *dstbuf, size_t dlen )
+{
+    int ret = 0;
+    size_t i;
+    mbedtls_md5_context md5;
+    mbedtls_sha1_context sha1;
+    unsigned char padding[16];
+    unsigned char sha1sum[20];
+    ((void)label);
+
+    mbedtls_md5_init(  &md5  );
+    mbedtls_sha1_init( &sha1 );
+
+    /*
+     *  SSLv3:
+     *    block =
+     *      MD5( secret + SHA1( 'A'    + secret + random ) ) +
+     *      MD5( secret + SHA1( 'BB'   + secret + random ) ) +
+     *      MD5( secret + SHA1( 'CCC'  + secret + random ) ) +
+     *      ...
+     */
+    for( i = 0; i < dlen / 16; i++ )
+    {
+        memset( padding, (unsigned char) ('A' + i), 1 + i );
+
+        if( ( ret = mbedtls_sha1_starts_ret( &sha1 ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_sha1_update_ret( &sha1, padding, 1 + i ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_sha1_update_ret( &sha1, secret, slen ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_sha1_update_ret( &sha1, random, rlen ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_sha1_finish_ret( &sha1, sha1sum ) ) != 0 )
+            goto exit;
+
+        if( ( ret = mbedtls_md5_starts_ret( &md5 ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_md5_update_ret( &md5, secret, slen ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_md5_update_ret( &md5, sha1sum, 20 ) ) != 0 )
+            goto exit;
+        if( ( ret = mbedtls_md5_finish_ret( &md5, dstbuf + i * 16 ) ) != 0 )
+            goto exit;
+    }
+
+exit:
+    mbedtls_md5_free(  &md5  );
+    mbedtls_sha1_free( &sha1 );
+
+    mbedtls_platform_zeroize( padding, sizeof( padding ) );
+    mbedtls_platform_zeroize( sha1sum, sizeof( sha1sum ) );
+
+    return( ret );
+}
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
+static int tls1_prf( const unsigned char *secret, size_t slen,
+                     const char *label,
+                     const unsigned char *random, size_t rlen,
+                     unsigned char *dstbuf, size_t dlen )
+{
+    size_t nb, hs;
+    size_t i, j, k;
+    const unsigned char *S1, *S2;
+    unsigned char tmp[128];
+    unsigned char h_i[20];
+    const mbedtls_md_info_t *md_info;
+    mbedtls_md_context_t md_ctx;
+    int ret;
+
+    mbedtls_md_init( &md_ctx );
+
+    if( sizeof( tmp ) < 20 + strlen( label ) + rlen )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    hs = ( slen + 1 ) / 2;
+    S1 = secret;
+    S2 = secret + slen - hs;
+
+    nb = strlen( label );
+    memcpy( tmp + 20, label, nb );
+    memcpy( tmp + 20 + nb, random, rlen );
+    nb += rlen;
+
+    /*
+     * First compute P_md5(secret,label+random)[0..dlen]
+     */
+    if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_MD5 ) ) == NULL )
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
+        return( ret );
+
+    mbedtls_md_hmac_starts( &md_ctx, S1, hs );
+    mbedtls_md_hmac_update( &md_ctx, tmp + 20, nb );
+    mbedtls_md_hmac_finish( &md_ctx, 4 + tmp );
+
+    for( i = 0; i < dlen; i += 16 )
+    {
+        mbedtls_md_hmac_reset ( &md_ctx );
+        mbedtls_md_hmac_update( &md_ctx, 4 + tmp, 16 + nb );
+        mbedtls_md_hmac_finish( &md_ctx, h_i );
+
+        mbedtls_md_hmac_reset ( &md_ctx );
+        mbedtls_md_hmac_update( &md_ctx, 4 + tmp, 16 );
+        mbedtls_md_hmac_finish( &md_ctx, 4 + tmp );
+
+        k = ( i + 16 > dlen ) ? dlen % 16 : 16;
+
+        for( j = 0; j < k; j++ )
+            dstbuf[i + j]  = h_i[j];
+    }
+
+    mbedtls_md_free( &md_ctx );
+
+    /*
+     * XOR out with P_sha1(secret,label+random)[0..dlen]
+     */
+    if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 ) ) == NULL )
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+
+    if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
+        return( ret );
+
+    mbedtls_md_hmac_starts( &md_ctx, S2, hs );
+    mbedtls_md_hmac_update( &md_ctx, tmp + 20, nb );
+    mbedtls_md_hmac_finish( &md_ctx, tmp );
+
+    for( i = 0; i < dlen; i += 20 )
+    {
+        mbedtls_md_hmac_reset ( &md_ctx );
+        mbedtls_md_hmac_update( &md_ctx, tmp, 20 + nb );
+        mbedtls_md_hmac_finish( &md_ctx, h_i );
+
+        mbedtls_md_hmac_reset ( &md_ctx );
+        mbedtls_md_hmac_update( &md_ctx, tmp, 20 );
+        mbedtls_md_hmac_finish( &md_ctx, tmp );
+
+        k = ( i + 20 > dlen ) ? dlen % 20 : 20;
+
+        for( j = 0; j < k; j++ )
+            dstbuf[i + j] = (unsigned char)( dstbuf[i + j] ^ h_i[j] );
+    }
+
+    mbedtls_md_free( &md_ctx );
+
+    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
+    mbedtls_platform_zeroize( h_i, sizeof( h_i ) );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1) || MBEDTLS_SSL_PROTO_TLS1_1 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+static int tls_prf_generic( mbedtls_md_type_t md_type,
+                            const unsigned char *secret, size_t slen,
+                            const char *label,
+                            const unsigned char *random, size_t rlen,
+                            unsigned char *dstbuf, size_t dlen )
+{
+    psa_status_t status;
+    psa_algorithm_t alg;
+    psa_key_policy_t policy;
+    psa_key_handle_t master_slot;
+    psa_crypto_generator_t generator = PSA_CRYPTO_GENERATOR_INIT;
+
+    if( ( status = psa_allocate_key( &master_slot ) ) != PSA_SUCCESS )
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+
+    if( md_type == MBEDTLS_MD_SHA384 )
+        alg = PSA_ALG_TLS12_PRF(PSA_ALG_SHA_384);
+    else
+        alg = PSA_ALG_TLS12_PRF(PSA_ALG_SHA_256);
+
+    policy = psa_key_policy_init();
+    psa_key_policy_set_usage( &policy,
+                              PSA_KEY_USAGE_DERIVE,
+                              alg );
+    status = psa_set_key_policy( master_slot, &policy );
+    if( status != PSA_SUCCESS )
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+
+    status = psa_import_key( master_slot, PSA_KEY_TYPE_DERIVE, secret, slen );
+    if( status != PSA_SUCCESS )
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+
+    status = psa_key_derivation( &generator,
+                                 master_slot, alg,
+                                 random, rlen,
+                                 (unsigned char const *) label,
+                                 (size_t) strlen( label ),
+                                 dlen );
+    if( status != PSA_SUCCESS )
+    {
+        psa_generator_abort( &generator );
+        psa_destroy_key( master_slot );
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+    }
+
+    status = psa_generator_read( &generator, dstbuf, dlen );
+    if( status != PSA_SUCCESS )
+    {
+        psa_generator_abort( &generator );
+        psa_destroy_key( master_slot );
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+    }
+
+    status = psa_generator_abort( &generator );
+    if( status != PSA_SUCCESS )
+    {
+        psa_destroy_key( master_slot );
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+    }
+
+    status = psa_destroy_key( master_slot );
+    if( status != PSA_SUCCESS )
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+
+    return( 0 );
+}
+
+#else /* MBEDTLS_USE_PSA_CRYPTO */
+
+static int tls_prf_generic( mbedtls_md_type_t md_type,
+                            const unsigned char *secret, size_t slen,
+                            const char *label,
+                            const unsigned char *random, size_t rlen,
+                            unsigned char *dstbuf, size_t dlen )
+{
+    size_t nb;
+    size_t i, j, k, md_len;
+    unsigned char tmp[128];
+    unsigned char h_i[MBEDTLS_MD_MAX_SIZE];
+    const mbedtls_md_info_t *md_info;
+    mbedtls_md_context_t md_ctx;
+    int ret;
+
+    mbedtls_md_init( &md_ctx );
+
+    if( ( md_info = mbedtls_md_info_from_type( md_type ) ) == NULL )
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+
+    md_len = mbedtls_md_get_size( md_info );
+
+    if( sizeof( tmp ) < md_len + strlen( label ) + rlen )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    nb = strlen( label );
+    memcpy( tmp + md_len, label, nb );
+    memcpy( tmp + md_len + nb, random, rlen );
+    nb += rlen;
+
+    /*
+     * Compute P_<hash>(secret, label + random)[0..dlen]
+     */
+    if ( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
+        return( ret );
+
+    mbedtls_md_hmac_starts( &md_ctx, secret, slen );
+    mbedtls_md_hmac_update( &md_ctx, tmp + md_len, nb );
+    mbedtls_md_hmac_finish( &md_ctx, tmp );
+
+    for( i = 0; i < dlen; i += md_len )
+    {
+        mbedtls_md_hmac_reset ( &md_ctx );
+        mbedtls_md_hmac_update( &md_ctx, tmp, md_len + nb );
+        mbedtls_md_hmac_finish( &md_ctx, h_i );
+
+        mbedtls_md_hmac_reset ( &md_ctx );
+        mbedtls_md_hmac_update( &md_ctx, tmp, md_len );
+        mbedtls_md_hmac_finish( &md_ctx, tmp );
+
+        k = ( i + md_len > dlen ) ? dlen % md_len : md_len;
+
+        for( j = 0; j < k; j++ )
+            dstbuf[i + j]  = h_i[j];
+    }
+
+    mbedtls_md_free( &md_ctx );
+
+    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
+    mbedtls_platform_zeroize( h_i, sizeof( h_i ) );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+#if defined(MBEDTLS_SHA256_C)
+static int tls_prf_sha256( const unsigned char *secret, size_t slen,
+                           const char *label,
+                           const unsigned char *random, size_t rlen,
+                           unsigned char *dstbuf, size_t dlen )
+{
+    return( tls_prf_generic( MBEDTLS_MD_SHA256, secret, slen,
+                             label, random, rlen, dstbuf, dlen ) );
+}
+#endif /* MBEDTLS_SHA256_C */
+
+#if defined(MBEDTLS_SHA512_C)
+static int tls_prf_sha384( const unsigned char *secret, size_t slen,
+                           const char *label,
+                           const unsigned char *random, size_t rlen,
+                           unsigned char *dstbuf, size_t dlen )
+{
+    return( tls_prf_generic( MBEDTLS_MD_SHA384, secret, slen,
+                             label, random, rlen, dstbuf, dlen ) );
+}
+#endif /* MBEDTLS_SHA512_C */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+static void ssl_update_checksum_start( mbedtls_ssl_context *, const unsigned char *, size_t );
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+static void ssl_update_checksum_md5sha1( mbedtls_ssl_context *, const unsigned char *, size_t );
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+static void ssl_calc_verify_ssl( mbedtls_ssl_context *, unsigned char * );
+static void ssl_calc_finished_ssl( mbedtls_ssl_context *, unsigned char *, int );
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
+static void ssl_calc_verify_tls( mbedtls_ssl_context *, unsigned char * );
+static void ssl_calc_finished_tls( mbedtls_ssl_context *, unsigned char *, int );
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+static void ssl_update_checksum_sha256( mbedtls_ssl_context *, const unsigned char *, size_t );
+static void ssl_calc_verify_tls_sha256( mbedtls_ssl_context *,unsigned char * );
+static void ssl_calc_finished_tls_sha256( mbedtls_ssl_context *,unsigned char *, int );
+#endif
+
+#if defined(MBEDTLS_SHA512_C)
+static void ssl_update_checksum_sha384( mbedtls_ssl_context *, const unsigned char *, size_t );
+static void ssl_calc_verify_tls_sha384( mbedtls_ssl_context *, unsigned char * );
+static void ssl_calc_finished_tls_sha384( mbedtls_ssl_context *, unsigned char *, int );
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED) && \
+    defined(MBEDTLS_USE_PSA_CRYPTO)
+static int ssl_use_opaque_psk( mbedtls_ssl_context const *ssl )
+{
+    if( ssl->conf->f_psk != NULL )
+    {
+        /* If we've used a callback to select the PSK,
+         * the static configuration is irrelevant. */
+        if( ssl->handshake->psk_opaque != 0 )
+            return( 1 );
+
+        return( 0 );
+    }
+
+    if( ssl->conf->psk_opaque != 0 )
+        return( 1 );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO &&
+          MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
+
+int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
+{
+    int ret = 0;
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    int psa_fallthrough;
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    unsigned char tmp[64];
+    unsigned char keyblk[256];
+    unsigned char *key1;
+    unsigned char *key2;
+    unsigned char *mac_enc;
+    unsigned char *mac_dec;
+    size_t mac_key_len;
+    size_t iv_copy_len;
+    size_t taglen = 0;
+    const mbedtls_cipher_info_t *cipher_info;
+    const mbedtls_md_info_t *md_info;
+
+    /* cf. RFC 5246, Section 8.1:
+     * "The master secret is always exactly 48 bytes in length." */
+    size_t const master_secret_len = 48;
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+    unsigned char session_hash[48];
+#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
+
+    mbedtls_ssl_session *session = ssl->session_negotiate;
+    mbedtls_ssl_transform *transform = ssl->transform_negotiate;
+    mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> derive keys" ) );
+
+    cipher_info = mbedtls_cipher_info_from_type( transform->ciphersuite_info->cipher );
+    if( cipher_info == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "cipher info for %d not found",
+                            transform->ciphersuite_info->cipher ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    md_info = mbedtls_md_info_from_type( transform->ciphersuite_info->mac );
+    if( md_info == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "mbedtls_md info for %d not found",
+                            transform->ciphersuite_info->mac ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    /*
+     * Set appropriate PRF function and other SSL / TLS / TLS1.2 functions
+     */
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+    {
+        handshake->tls_prf = ssl3_prf;
+        handshake->calc_verify = ssl_calc_verify_ssl;
+        handshake->calc_finished = ssl_calc_finished_ssl;
+    }
+    else
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
+    if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        handshake->tls_prf = tls1_prf;
+        handshake->calc_verify = ssl_calc_verify_tls;
+        handshake->calc_finished = ssl_calc_finished_tls;
+    }
+    else
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA512_C)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
+        transform->ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
+    {
+        handshake->tls_prf = tls_prf_sha384;
+        handshake->calc_verify = ssl_calc_verify_tls_sha384;
+        handshake->calc_finished = ssl_calc_finished_tls_sha384;
+    }
+    else
+#endif
+#if defined(MBEDTLS_SHA256_C)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        handshake->tls_prf = tls_prf_sha256;
+        handshake->calc_verify = ssl_calc_verify_tls_sha256;
+        handshake->calc_finished = ssl_calc_finished_tls_sha256;
+    }
+    else
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    /*
+     * SSLv3:
+     *   master =
+     *     MD5( premaster + SHA1( 'A'   + premaster + randbytes ) ) +
+     *     MD5( premaster + SHA1( 'BB'  + premaster + randbytes ) ) +
+     *     MD5( premaster + SHA1( 'CCC' + premaster + randbytes ) )
+     *
+     * TLSv1+:
+     *   master = PRF( premaster, "master secret", randbytes )[0..47]
+     */
+    if( handshake->resume != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
+    }
+    else
+    {
+        /* The label for the KDF used for key expansion.
+         * This is either "master secret" or "extended master secret"
+         * depending on whether the Extended Master Secret extension
+         * is used. */
+        char const *lbl = "master secret";
+
+        /* The salt for the KDF used for key expansion.
+         * - If the Extended Master Secret extension is not used,
+         *   this is ClientHello.Random + ServerHello.Random
+         *   (see Sect. 8.1 in RFC 5246).
+         * - If the Extended Master Secret extension is used,
+         *   this is the transcript of the handshake so far.
+         *   (see Sect. 4 in RFC 7627). */
+        unsigned char const *salt = handshake->randbytes;
+        size_t salt_len = 64;
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+        const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+            ssl->transform_negotiate->ciphersuite_info;
+        mbedtls_md_type_t const md_type = ciphersuite_info->mac;
+#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+        if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) );
+
+            lbl  = "extended master secret";
+            salt = session_hash;
+            ssl->handshake->calc_verify( ssl, session_hash );
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+            if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+            {
+#if defined(MBEDTLS_SHA512_C)
+                if( md_type == MBEDTLS_MD_SHA384 )
+                    salt_len = 48;
+                else
+#endif /* MBEDTLS_SHA512_C */
+                    salt_len = 32;
+            }
+            else
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+                salt_len = 36;
+
+            MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, salt_len );
+        }
+#endif /* MBEDTLS_SSL_EXTENDED_MS_ENABLED */
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO) &&          \
+    defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK &&
+            ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
+            ssl_use_opaque_psk( ssl ) == 1 )
+        {
+            /* Perform PSK-to-MS expansion in a single step. */
+            psa_status_t status;
+            psa_algorithm_t alg;
+            psa_crypto_generator_t generator = PSA_CRYPTO_GENERATOR_INIT;
+            psa_key_handle_t psk;
+
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "perform PSA-based PSK-to-MS expansion" ) );
+
+            psk = ssl->conf->psk_opaque;
+            if( ssl->handshake->psk_opaque != 0 )
+                psk = ssl->handshake->psk_opaque;
+
+            if( md_type == MBEDTLS_MD_SHA384 )
+                alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_384);
+            else
+                alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256);
+
+            status = psa_key_derivation( &generator, psk, alg,
+                                         salt, salt_len,
+                                         (unsigned char const *) lbl,
+                                         (size_t) strlen( lbl ),
+                                         master_secret_len );
+            if( status != PSA_SUCCESS )
+            {
+                psa_generator_abort( &generator );
+                return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+            }
+
+            status = psa_generator_read( &generator, session->master,
+                                         master_secret_len );
+            if( status != PSA_SUCCESS )
+            {
+                psa_generator_abort( &generator );
+                return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+            }
+
+            status = psa_generator_abort( &generator );
+            if( status != PSA_SUCCESS )
+                return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+        else
+#endif
+        {
+            ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
+                                      lbl, salt, salt_len,
+                                      session->master,
+                                      master_secret_len );
+            if( ret != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
+                return( ret );
+            }
+
+            MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret",
+                                   handshake->premaster,
+                                   handshake->pmslen );
+
+            mbedtls_platform_zeroize( handshake->premaster,
+                                      sizeof(handshake->premaster) );
+        }
+    }
+
+    /*
+     * Swap the client and server random values.
+     */
+    memcpy( tmp, handshake->randbytes, 64 );
+    memcpy( handshake->randbytes, tmp + 32, 32 );
+    memcpy( handshake->randbytes + 32, tmp, 32 );
+    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
+
+    /*
+     *  SSLv3:
+     *    key block =
+     *      MD5( master + SHA1( 'A'    + master + randbytes ) ) +
+     *      MD5( master + SHA1( 'BB'   + master + randbytes ) ) +
+     *      MD5( master + SHA1( 'CCC'  + master + randbytes ) ) +
+     *      MD5( master + SHA1( 'DDDD' + master + randbytes ) ) +
+     *      ...
+     *
+     *  TLSv1:
+     *    key block = PRF( master, "key expansion", randbytes )
+     */
+    ret = handshake->tls_prf( session->master, 48, "key expansion",
+                              handshake->randbytes, 64, keyblk, 256 );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "ciphersuite = %s",
+                   mbedtls_ssl_get_ciphersuite_name( session->ciphersuite ) ) );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "master secret", session->master, 48 );
+    MBEDTLS_SSL_DEBUG_BUF( 4, "random bytes", handshake->randbytes, 64 );
+    MBEDTLS_SSL_DEBUG_BUF( 4, "key block", keyblk, 256 );
+
+    mbedtls_platform_zeroize( handshake->randbytes,
+                              sizeof( handshake->randbytes ) );
+
+    /*
+     * Determine the appropriate key, IV and MAC length.
+     */
+
+    transform->keylen = cipher_info->key_bitlen / 8;
+
+    if( cipher_info->mode == MBEDTLS_MODE_GCM ||
+        cipher_info->mode == MBEDTLS_MODE_CCM ||
+        cipher_info->mode == MBEDTLS_MODE_CHACHAPOLY )
+    {
+        size_t explicit_ivlen;
+
+        transform->maclen = 0;
+        mac_key_len = 0;
+
+        /* All modes haves 96-bit IVs;
+         * GCM and CCM has 4 implicit and 8 explicit bytes
+         * ChachaPoly has all 12 bytes implicit
+         */
+        transform->ivlen = 12;
+        if( cipher_info->mode == MBEDTLS_MODE_CHACHAPOLY )
+            transform->fixed_ivlen = 12;
+        else
+            transform->fixed_ivlen = 4;
+
+        /* All modes have 128-bit tags, except CCM_8 (ciphersuite flag) */
+        taglen = transform->ciphersuite_info->flags &
+                  MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16;
+
+
+        /* Minimum length of encrypted record */
+        explicit_ivlen = transform->ivlen - transform->fixed_ivlen;
+        transform->minlen = explicit_ivlen + taglen;
+    }
+    else
+    {
+        /* Initialize HMAC contexts */
+        if( ( ret = mbedtls_md_setup( &transform->md_ctx_enc, md_info, 1 ) ) != 0 ||
+            ( ret = mbedtls_md_setup( &transform->md_ctx_dec, md_info, 1 ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_setup", ret );
+            return( ret );
+        }
+
+        /* Get MAC length */
+        mac_key_len = mbedtls_md_get_size( md_info );
+        transform->maclen = mac_key_len;
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+        /*
+         * If HMAC is to be truncated, we shall keep the leftmost bytes,
+         * (rfc 6066 page 13 or rfc 2104 section 4),
+         * so we only need to adjust the length here.
+         */
+        if( session->trunc_hmac == MBEDTLS_SSL_TRUNC_HMAC_ENABLED )
+        {
+            transform->maclen = MBEDTLS_SSL_TRUNCATED_HMAC_LEN;
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT)
+            /* Fall back to old, non-compliant version of the truncated
+             * HMAC implementation which also truncates the key
+             * (Mbed TLS versions from 1.3 to 2.6.0) */
+            mac_key_len = transform->maclen;
+#endif
+        }
+#endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
+
+        /* IV length */
+        transform->ivlen = cipher_info->iv_size;
+
+        /* Minimum length */
+        if( cipher_info->mode == MBEDTLS_MODE_STREAM )
+            transform->minlen = transform->maclen;
+        else
+        {
+            /*
+             * GenericBlockCipher:
+             * 1. if EtM is in use: one block plus MAC
+             *    otherwise: * first multiple of blocklen greater than maclen
+             * 2. IV except for SSL3 and TLS 1.0
+             */
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+            if( session->encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED )
+            {
+                transform->minlen = transform->maclen
+                                  + cipher_info->block_size;
+            }
+            else
+#endif
+            {
+                transform->minlen = transform->maclen
+                                  + cipher_info->block_size
+                                  - transform->maclen % cipher_info->block_size;
+            }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1)
+            if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 ||
+                ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_1 )
+                ; /* No need to adjust minlen */
+            else
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
+            if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_2 ||
+                ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+            {
+                transform->minlen += transform->ivlen;
+            }
+            else
+#endif
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+                return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+            }
+        }
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "keylen: %d, minlen: %d, ivlen: %d, maclen: %d",
+                   transform->keylen, transform->minlen, transform->ivlen,
+                   transform->maclen ) );
+
+    /*
+     * Finally setup the cipher contexts, IVs and MAC secrets.
+     */
+#if defined(MBEDTLS_SSL_CLI_C)
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+    {
+        key1 = keyblk + mac_key_len * 2;
+        key2 = keyblk + mac_key_len * 2 + transform->keylen;
+
+        mac_enc = keyblk;
+        mac_dec = keyblk + mac_key_len;
+
+        /*
+         * This is not used in TLS v1.1.
+         */
+        iv_copy_len = ( transform->fixed_ivlen ) ?
+                            transform->fixed_ivlen : transform->ivlen;
+        memcpy( transform->iv_enc, key2 + transform->keylen,  iv_copy_len );
+        memcpy( transform->iv_dec, key2 + transform->keylen + iv_copy_len,
+                iv_copy_len );
+    }
+    else
+#endif /* MBEDTLS_SSL_CLI_C */
+#if defined(MBEDTLS_SSL_SRV_C)
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        key1 = keyblk + mac_key_len * 2 + transform->keylen;
+        key2 = keyblk + mac_key_len * 2;
+
+        mac_enc = keyblk + mac_key_len;
+        mac_dec = keyblk;
+
+        /*
+         * This is not used in TLS v1.1.
+         */
+        iv_copy_len = ( transform->fixed_ivlen ) ?
+                            transform->fixed_ivlen : transform->ivlen;
+        memcpy( transform->iv_dec, key1 + transform->keylen,  iv_copy_len );
+        memcpy( transform->iv_enc, key1 + transform->keylen + iv_copy_len,
+                iv_copy_len );
+    }
+    else
+#endif /* MBEDTLS_SSL_SRV_C */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+    {
+        if( mac_key_len > sizeof transform->mac_enc )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        memcpy( transform->mac_enc, mac_enc, mac_key_len );
+        memcpy( transform->mac_dec, mac_dec, mac_key_len );
+    }
+    else
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
+    {
+        /* For HMAC-based ciphersuites, initialize the HMAC transforms.
+           For AEAD-based ciphersuites, there is nothing to do here. */
+        if( mac_key_len != 0 )
+        {
+            mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, mac_key_len );
+            mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, mac_key_len );
+        }
+    }
+    else
+#endif
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_init != NULL )
+    {
+        int ret = 0;
+
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_init()" ) );
+
+        if( ( ret = mbedtls_ssl_hw_record_init( ssl, key1, key2, transform->keylen,
+                                        transform->iv_enc, transform->iv_dec,
+                                        iv_copy_len,
+                                        mac_enc, mac_dec,
+                                        mac_key_len ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_init", ret );
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+    }
+#endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
+
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+    if( ssl->conf->f_export_keys != NULL )
+    {
+        ssl->conf->f_export_keys( ssl->conf->p_export_keys,
+                                  session->master, keyblk,
+                                  mac_key_len, transform->keylen,
+                                  iv_copy_len );
+    }
+#endif
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+
+    /* Only use PSA-based ciphers for TLS-1.2.
+     * That's relevant at least for TLS-1.0, where
+     * we assume that mbedtls_cipher_crypt() updates
+     * the structure field for the IV, which the PSA-based
+     * implementation currently doesn't. */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        ret = mbedtls_cipher_setup_psa( &transform->cipher_ctx_enc,
+                                        cipher_info, taglen );
+        if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup_psa", ret );
+            return( ret );
+        }
+
+        if( ret == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "Successfully setup PSA-based encryption cipher context" ) );
+            psa_fallthrough = 0;
+        }
+        else
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "Failed to setup PSA-based cipher context for record encryption - fall through to default setup." ) );
+            psa_fallthrough = 1;
+        }
+    }
+    else
+        psa_fallthrough = 1;
+#else
+    psa_fallthrough = 1;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+    if( psa_fallthrough == 1 )
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_enc,
+                                 cipher_info ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
+        return( ret );
+    }
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    /* Only use PSA-based ciphers for TLS-1.2.
+     * That's relevant at least for TLS-1.0, where
+     * we assume that mbedtls_cipher_crypt() updates
+     * the structure field for the IV, which the PSA-based
+     * implementation currently doesn't. */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        ret = mbedtls_cipher_setup_psa( &transform->cipher_ctx_dec,
+                                        cipher_info, taglen );
+        if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup_psa", ret );
+            return( ret );
+        }
+
+        if( ret == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "Successfully setup PSA-based decryption cipher context" ) );
+            psa_fallthrough = 0;
+        }
+        else
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "Failed to setup PSA-based cipher context for record decryption - fall through to default setup." ) );
+            psa_fallthrough = 1;
+        }
+    }
+    else
+        psa_fallthrough = 1;
+#else
+    psa_fallthrough = 1;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+    if( psa_fallthrough == 1 )
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_dec,
+                                 cipher_info ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
+        return( ret );
+    }
+
+    if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_enc, key1,
+                               cipher_info->key_bitlen,
+                               MBEDTLS_ENCRYPT ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
+        return( ret );
+    }
+
+    if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_dec, key2,
+                               cipher_info->key_bitlen,
+                               MBEDTLS_DECRYPT ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
+        return( ret );
+    }
+
+#if defined(MBEDTLS_CIPHER_MODE_CBC)
+    if( cipher_info->mode == MBEDTLS_MODE_CBC )
+    {
+        if( ( ret = mbedtls_cipher_set_padding_mode( &transform->cipher_ctx_enc,
+                                             MBEDTLS_PADDING_NONE ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_set_padding_mode", ret );
+            return( ret );
+        }
+
+        if( ( ret = mbedtls_cipher_set_padding_mode( &transform->cipher_ctx_dec,
+                                             MBEDTLS_PADDING_NONE ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_set_padding_mode", ret );
+            return( ret );
+        }
+    }
+#endif /* MBEDTLS_CIPHER_MODE_CBC */
+
+    mbedtls_platform_zeroize( keyblk, sizeof( keyblk ) );
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    // Initialize compression
+    //
+    if( session->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
+    {
+        if( ssl->compress_buf == NULL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "Allocating compression buffer" ) );
+            ssl->compress_buf = mbedtls_calloc( 1, MBEDTLS_SSL_COMPRESS_BUFFER_LEN );
+            if( ssl->compress_buf == NULL )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
+                                    MBEDTLS_SSL_COMPRESS_BUFFER_LEN ) );
+                return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+            }
+        }
+
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "Initializing zlib states" ) );
+
+        memset( &transform->ctx_deflate, 0, sizeof( transform->ctx_deflate ) );
+        memset( &transform->ctx_inflate, 0, sizeof( transform->ctx_inflate ) );
+
+        if( deflateInit( &transform->ctx_deflate,
+                         Z_DEFAULT_COMPRESSION )   != Z_OK ||
+            inflateInit( &transform->ctx_inflate ) != Z_OK )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "Failed to initialize compression" ) );
+            return( MBEDTLS_ERR_SSL_COMPRESSION_FAILED );
+        }
+    }
+#endif /* MBEDTLS_ZLIB_SUPPORT */
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= derive keys" ) );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+void ssl_calc_verify_ssl( mbedtls_ssl_context *ssl, unsigned char hash[36] )
+{
+    mbedtls_md5_context md5;
+    mbedtls_sha1_context sha1;
+    unsigned char pad_1[48];
+    unsigned char pad_2[48];
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify ssl" ) );
+
+    mbedtls_md5_init( &md5 );
+    mbedtls_sha1_init( &sha1 );
+
+    mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
+    mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
+
+    memset( pad_1, 0x36, 48 );
+    memset( pad_2, 0x5C, 48 );
+
+    mbedtls_md5_update_ret( &md5, ssl->session_negotiate->master, 48 );
+    mbedtls_md5_update_ret( &md5, pad_1, 48 );
+    mbedtls_md5_finish_ret( &md5, hash );
+
+    mbedtls_md5_starts_ret( &md5 );
+    mbedtls_md5_update_ret( &md5, ssl->session_negotiate->master, 48 );
+    mbedtls_md5_update_ret( &md5, pad_2, 48 );
+    mbedtls_md5_update_ret( &md5, hash,  16 );
+    mbedtls_md5_finish_ret( &md5, hash );
+
+    mbedtls_sha1_update_ret( &sha1, ssl->session_negotiate->master, 48 );
+    mbedtls_sha1_update_ret( &sha1, pad_1, 40 );
+    mbedtls_sha1_finish_ret( &sha1, hash + 16 );
+
+    mbedtls_sha1_starts_ret( &sha1 );
+    mbedtls_sha1_update_ret( &sha1, ssl->session_negotiate->master, 48 );
+    mbedtls_sha1_update_ret( &sha1, pad_2, 40 );
+    mbedtls_sha1_update_ret( &sha1, hash + 16, 20 );
+    mbedtls_sha1_finish_ret( &sha1, hash + 16 );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 36 );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
+
+    mbedtls_md5_free(  &md5  );
+    mbedtls_sha1_free( &sha1 );
+
+    return;
+}
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
+void ssl_calc_verify_tls( mbedtls_ssl_context *ssl, unsigned char hash[36] )
+{
+    mbedtls_md5_context md5;
+    mbedtls_sha1_context sha1;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify tls" ) );
+
+    mbedtls_md5_init( &md5 );
+    mbedtls_sha1_init( &sha1 );
+
+    mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
+    mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
+
+    mbedtls_md5_finish_ret( &md5,  hash );
+    mbedtls_sha1_finish_ret( &sha1, hash + 16 );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 36 );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
+
+    mbedtls_md5_free(  &md5  );
+    mbedtls_sha1_free( &sha1 );
+
+    return;
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+void ssl_calc_verify_tls_sha256( mbedtls_ssl_context *ssl, unsigned char hash[32] )
+{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    size_t hash_size;
+    psa_status_t status;
+    psa_hash_operation_t sha256_psa = psa_hash_operation_init();
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> PSA calc verify sha256" ) );
+    status = psa_hash_clone( &ssl->handshake->fin_sha256_psa, &sha256_psa );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash clone failed" ) );
+        return;
+    }
+
+    status = psa_hash_finish( &sha256_psa, hash, 32, &hash_size );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash finish failed" ) );
+        return;
+    }
+    MBEDTLS_SSL_DEBUG_BUF( 3, "PSA calculated verify result", hash, 32 );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= PSA calc verify" ) );
+#else
+    mbedtls_sha256_context sha256;
+
+    mbedtls_sha256_init( &sha256 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify sha256" ) );
+
+    mbedtls_sha256_clone( &sha256, &ssl->handshake->fin_sha256 );
+    mbedtls_sha256_finish_ret( &sha256, hash );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 32 );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
+
+    mbedtls_sha256_free( &sha256 );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    return;
+}
+#endif /* MBEDTLS_SHA256_C */
+
+#if defined(MBEDTLS_SHA512_C)
+void ssl_calc_verify_tls_sha384( mbedtls_ssl_context *ssl, unsigned char hash[48] )
+{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    size_t hash_size;
+    psa_status_t status;
+    psa_hash_operation_t sha384_psa = psa_hash_operation_init();
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> PSA calc verify sha384" ) );
+    status = psa_hash_clone( &ssl->handshake->fin_sha384_psa, &sha384_psa );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash clone failed" ) );
+        return;
+    }
+
+    status = psa_hash_finish( &sha384_psa, hash, 48, &hash_size );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash finish failed" ) );
+        return;
+    }
+    MBEDTLS_SSL_DEBUG_BUF( 3, "PSA calculated verify result", hash, 48 );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= PSA calc verify" ) );
+#else
+    mbedtls_sha512_context sha512;
+
+    mbedtls_sha512_init( &sha512 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify sha384" ) );
+
+    mbedtls_sha512_clone( &sha512, &ssl->handshake->fin_sha512 );
+    mbedtls_sha512_finish_ret( &sha512, hash );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 48 );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
+
+    mbedtls_sha512_free( &sha512 );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    return;
+}
+#endif /* MBEDTLS_SHA512_C */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
+int mbedtls_ssl_psk_derive_premaster( mbedtls_ssl_context *ssl, mbedtls_key_exchange_type_t key_ex )
+{
+    unsigned char *p = ssl->handshake->premaster;
+    unsigned char *end = p + sizeof( ssl->handshake->premaster );
+    const unsigned char *psk = ssl->conf->psk;
+    size_t psk_len = ssl->conf->psk_len;
+
+    /* If the psk callback was called, use its result */
+    if( ssl->handshake->psk != NULL )
+    {
+        psk = ssl->handshake->psk;
+        psk_len = ssl->handshake->psk_len;
+    }
+
+    /*
+     * PMS = struct {
+     *     opaque other_secret<0..2^16-1>;
+     *     opaque psk<0..2^16-1>;
+     * };
+     * with "other_secret" depending on the particular key exchange
+     */
+#if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
+    if( key_ex == MBEDTLS_KEY_EXCHANGE_PSK )
+    {
+        if( end - p < 2 )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+        *(p++) = (unsigned char)( psk_len >> 8 );
+        *(p++) = (unsigned char)( psk_len      );
+
+        if( end < p || (size_t)( end - p ) < psk_len )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+        memset( p, 0, psk_len );
+        p += psk_len;
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_PSK_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)
+    if( key_ex == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
+    {
+        /*
+         * other_secret already set by the ClientKeyExchange message,
+         * and is 48 bytes long
+         */
+        if( end - p < 2 )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+        *p++ = 0;
+        *p++ = 48;
+        p += 48;
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED)
+    if( key_ex == MBEDTLS_KEY_EXCHANGE_DHE_PSK )
+    {
+        int ret;
+        size_t len;
+
+        /* Write length only when we know the actual value */
+        if( ( ret = mbedtls_dhm_calc_secret( &ssl->handshake->dhm_ctx,
+                                      p + 2, end - ( p + 2 ), &len,
+                                      ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_calc_secret", ret );
+            return( ret );
+        }
+        *(p++) = (unsigned char)( len >> 8 );
+        *(p++) = (unsigned char)( len );
+        p += len;
+
+        MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K  );
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
+    if( key_ex == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK )
+    {
+        int ret;
+        size_t zlen;
+
+        if( ( ret = mbedtls_ecdh_calc_secret( &ssl->handshake->ecdh_ctx, &zlen,
+                                       p + 2, end - ( p + 2 ),
+                                       ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
+            return( ret );
+        }
+
+        *(p++) = (unsigned char)( zlen >> 8 );
+        *(p++) = (unsigned char)( zlen      );
+        p += zlen;
+
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Z );
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    /* opaque psk<0..2^16-1>; */
+    if( end - p < 2 )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    *(p++) = (unsigned char)( psk_len >> 8 );
+    *(p++) = (unsigned char)( psk_len      );
+
+    if( end < p || (size_t)( end - p ) < psk_len )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    memcpy( p, psk, psk_len );
+    p += psk_len;
+
+    ssl->handshake->pmslen = p - ssl->handshake->premaster;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+/*
+ * SSLv3.0 MAC functions
+ */
+#define SSL_MAC_MAX_BYTES   20  /* MD-5 or SHA-1 */
+static void ssl_mac( mbedtls_md_context_t *md_ctx,
+                     const unsigned char *secret,
+                     const unsigned char *buf, size_t len,
+                     const unsigned char *ctr, int type,
+                     unsigned char out[SSL_MAC_MAX_BYTES] )
+{
+    unsigned char header[11];
+    unsigned char padding[48];
+    int padlen;
+    int md_size = mbedtls_md_get_size( md_ctx->md_info );
+    int md_type = mbedtls_md_get_type( md_ctx->md_info );
+
+    /* Only MD5 and SHA-1 supported */
+    if( md_type == MBEDTLS_MD_MD5 )
+        padlen = 48;
+    else
+        padlen = 40;
+
+    memcpy( header, ctr, 8 );
+    header[ 8] = (unsigned char)  type;
+    header[ 9] = (unsigned char)( len >> 8 );
+    header[10] = (unsigned char)( len      );
+
+    memset( padding, 0x36, padlen );
+    mbedtls_md_starts( md_ctx );
+    mbedtls_md_update( md_ctx, secret,  md_size );
+    mbedtls_md_update( md_ctx, padding, padlen  );
+    mbedtls_md_update( md_ctx, header,  11      );
+    mbedtls_md_update( md_ctx, buf,     len     );
+    mbedtls_md_finish( md_ctx, out              );
+
+    memset( padding, 0x5C, padlen );
+    mbedtls_md_starts( md_ctx );
+    mbedtls_md_update( md_ctx, secret,    md_size );
+    mbedtls_md_update( md_ctx, padding,   padlen  );
+    mbedtls_md_update( md_ctx, out,       md_size );
+    mbedtls_md_finish( md_ctx, out                );
+}
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+
+#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER) ||     \
+    ( defined(MBEDTLS_CIPHER_MODE_CBC) &&                                  \
+      ( defined(MBEDTLS_AES_C) || defined(MBEDTLS_CAMELLIA_C) || defined(MBEDTLS_ARIA_C)) )
+#define SSL_SOME_MODES_USE_MAC
+#endif
+
+/* The function below is only used in the Lucky 13 counter-measure in
+ * ssl_decrypt_buf(). These are the defines that guard the call site. */
+#if defined(SSL_SOME_MODES_USE_MAC) && \
+    ( defined(MBEDTLS_SSL_PROTO_TLS1) || \
+      defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+      defined(MBEDTLS_SSL_PROTO_TLS1_2) )
+/* This function makes sure every byte in the memory region is accessed
+ * (in ascending addresses order) */
+static void ssl_read_memory( unsigned char *p, size_t len )
+{
+    unsigned char acc = 0;
+    volatile unsigned char force;
+
+    for( ; len != 0; p++, len-- )
+        acc ^= *p;
+
+    force = acc;
+    (void) force;
+}
+#endif /* SSL_SOME_MODES_USE_MAC && ( TLS1 || TLS1_1 || TLS1_2 ) */
+
+/*
+ * Encryption/decryption functions
+ */
+static int ssl_encrypt_buf( mbedtls_ssl_context *ssl )
+{
+    mbedtls_cipher_mode_t mode;
+    int auth_done = 0;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> encrypt buf" ) );
+
+    if( ssl->session_out == NULL || ssl->transform_out == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    mode = mbedtls_cipher_get_cipher_mode( &ssl->transform_out->cipher_ctx_enc );
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "before encrypt: output payload",
+                      ssl->out_msg, ssl->out_msglen );
+
+    /*
+     * Add MAC before if needed
+     */
+#if defined(SSL_SOME_MODES_USE_MAC)
+    if( mode == MBEDTLS_MODE_STREAM ||
+        ( mode == MBEDTLS_MODE_CBC
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+          && ssl->session_out->encrypt_then_mac == MBEDTLS_SSL_ETM_DISABLED
+#endif
+        ) )
+    {
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+        {
+            unsigned char mac[SSL_MAC_MAX_BYTES];
+
+            ssl_mac( &ssl->transform_out->md_ctx_enc,
+                      ssl->transform_out->mac_enc,
+                      ssl->out_msg, ssl->out_msglen,
+                      ssl->out_ctr, ssl->out_msgtype,
+                      mac );
+
+            memcpy( ssl->out_msg + ssl->out_msglen, mac, ssl->transform_out->maclen );
+        }
+        else
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+        defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
+        {
+            unsigned char mac[MBEDTLS_SSL_MAC_ADD];
+
+            mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_ctr, 8 );
+            mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_hdr, 3 );
+            mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_len, 2 );
+            mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc,
+                             ssl->out_msg, ssl->out_msglen );
+            mbedtls_md_hmac_finish( &ssl->transform_out->md_ctx_enc, mac );
+            mbedtls_md_hmac_reset( &ssl->transform_out->md_ctx_enc );
+
+            memcpy( ssl->out_msg + ssl->out_msglen, mac, ssl->transform_out->maclen );
+        }
+        else
+#endif
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac",
+                       ssl->out_msg + ssl->out_msglen,
+                       ssl->transform_out->maclen );
+
+        ssl->out_msglen += ssl->transform_out->maclen;
+        auth_done++;
+    }
+#endif /* AEAD not the only option */
+
+    /*
+     * Encrypt
+     */
+#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
+    if( mode == MBEDTLS_MODE_STREAM )
+    {
+        int ret;
+        size_t olen = 0;
+
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %d, "
+                            "including %d bytes of padding",
+                       ssl->out_msglen, 0 ) );
+
+        if( ( ret = mbedtls_cipher_crypt( &ssl->transform_out->cipher_ctx_enc,
+                                   ssl->transform_out->iv_enc,
+                                   ssl->transform_out->ivlen,
+                                   ssl->out_msg, ssl->out_msglen,
+                                   ssl->out_msg, &olen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
+            return( ret );
+        }
+
+        if( ssl->out_msglen != olen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+    }
+    else
+#endif /* MBEDTLS_ARC4_C || MBEDTLS_CIPHER_NULL_CIPHER */
+#if defined(MBEDTLS_GCM_C) || \
+    defined(MBEDTLS_CCM_C) || \
+    defined(MBEDTLS_CHACHAPOLY_C)
+    if( mode == MBEDTLS_MODE_GCM ||
+        mode == MBEDTLS_MODE_CCM ||
+        mode == MBEDTLS_MODE_CHACHAPOLY )
+    {
+        int ret;
+        size_t enc_msglen, olen;
+        unsigned char *enc_msg;
+        unsigned char add_data[13];
+        unsigned char iv[12];
+        mbedtls_ssl_transform *transform = ssl->transform_out;
+        unsigned char taglen = transform->ciphersuite_info->flags &
+                               MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16;
+        size_t explicit_ivlen = transform->ivlen - transform->fixed_ivlen;
+
+        /*
+         * Prepare additional authenticated data
+         */
+        memcpy( add_data, ssl->out_ctr, 8 );
+        add_data[8]  = ssl->out_msgtype;
+        mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
+                           ssl->conf->transport, add_data + 9 );
+        add_data[11] = ( ssl->out_msglen >> 8 ) & 0xFF;
+        add_data[12] = ssl->out_msglen & 0xFF;
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "additional data for AEAD", add_data, 13 );
+
+        /*
+         * Generate IV
+         */
+        if( transform->ivlen == 12 && transform->fixed_ivlen == 4 )
+        {
+            /* GCM and CCM: fixed || explicit (=seqnum) */
+            memcpy( iv, transform->iv_enc, transform->fixed_ivlen );
+            memcpy( iv + transform->fixed_ivlen, ssl->out_ctr, 8 );
+            memcpy( ssl->out_iv, ssl->out_ctr, 8 );
+
+        }
+        else if( transform->ivlen == 12 && transform->fixed_ivlen == 12 )
+        {
+            /* ChachaPoly: fixed XOR sequence number */
+            unsigned char i;
+
+            memcpy( iv, transform->iv_enc, transform->fixed_ivlen );
+
+            for( i = 0; i < 8; i++ )
+                iv[i+4] ^= ssl->out_ctr[i];
+        }
+        else
+        {
+            /* Reminder if we ever add an AEAD mode with a different size */
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "IV used (internal)",
+                                  iv, transform->ivlen );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "IV used (transmitted)",
+                                  ssl->out_iv, explicit_ivlen );
+
+        /*
+         * Fix message length with added IV
+         */
+        enc_msg = ssl->out_msg;
+        enc_msglen = ssl->out_msglen;
+        ssl->out_msglen += explicit_ivlen;
+
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %d, "
+                                    "including 0 bytes of padding",
+                                    ssl->out_msglen ) );
+
+        /*
+         * Encrypt and authenticate
+         */
+        if( ( ret = mbedtls_cipher_auth_encrypt( &transform->cipher_ctx_enc,
+                                         iv, transform->ivlen,
+                                         add_data, 13,
+                                         enc_msg, enc_msglen,
+                                         enc_msg, &olen,
+                                         enc_msg + enc_msglen, taglen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_encrypt", ret );
+            return( ret );
+        }
+
+        if( olen != enc_msglen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        ssl->out_msglen += taglen;
+        auth_done++;
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "after encrypt: tag", enc_msg + enc_msglen, taglen );
+    }
+    else
+#endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
+#if defined(MBEDTLS_CIPHER_MODE_CBC) &&                                    \
+    ( defined(MBEDTLS_AES_C) || defined(MBEDTLS_CAMELLIA_C) || defined(MBEDTLS_ARIA_C) )
+    if( mode == MBEDTLS_MODE_CBC )
+    {
+        int ret;
+        unsigned char *enc_msg;
+        size_t enc_msglen, padlen, olen = 0, i;
+
+        padlen = ssl->transform_out->ivlen - ( ssl->out_msglen + 1 ) %
+                 ssl->transform_out->ivlen;
+        if( padlen == ssl->transform_out->ivlen )
+            padlen = 0;
+
+        for( i = 0; i <= padlen; i++ )
+            ssl->out_msg[ssl->out_msglen + i] = (unsigned char) padlen;
+
+        ssl->out_msglen += padlen + 1;
+
+        enc_msglen = ssl->out_msglen;
+        enc_msg = ssl->out_msg;
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        /*
+         * Prepend per-record IV for block cipher in TLS v1.1 and up as per
+         * Method 1 (6.2.3.2. in RFC4346 and RFC5246)
+         */
+        if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
+        {
+            /*
+             * Generate IV
+             */
+            ret = ssl->conf->f_rng( ssl->conf->p_rng, ssl->transform_out->iv_enc,
+                                  ssl->transform_out->ivlen );
+            if( ret != 0 )
+                return( ret );
+
+            memcpy( ssl->out_iv, ssl->transform_out->iv_enc,
+                    ssl->transform_out->ivlen );
+
+            /*
+             * Fix pointer positions and message length with added IV
+             */
+            enc_msg = ssl->out_msg;
+            enc_msglen = ssl->out_msglen;
+            ssl->out_msglen += ssl->transform_out->ivlen;
+        }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
+
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %d, "
+                            "including %d bytes of IV and %d bytes of padding",
+                            ssl->out_msglen, ssl->transform_out->ivlen,
+                            padlen + 1 ) );
+
+        if( ( ret = mbedtls_cipher_crypt( &ssl->transform_out->cipher_ctx_enc,
+                                   ssl->transform_out->iv_enc,
+                                   ssl->transform_out->ivlen,
+                                   enc_msg, enc_msglen,
+                                   enc_msg, &olen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
+            return( ret );
+        }
+
+        if( enc_msglen != olen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1)
+        if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 )
+        {
+            /*
+             * Save IV in SSL3 and TLS1
+             */
+            memcpy( ssl->transform_out->iv_enc,
+                    ssl->transform_out->cipher_ctx_enc.iv,
+                    ssl->transform_out->ivlen );
+        }
+#endif
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+        if( auth_done == 0 )
+        {
+            unsigned char mac[MBEDTLS_SSL_MAC_ADD];
+
+            /*
+             * MAC(MAC_write_key, seq_num +
+             *     TLSCipherText.type +
+             *     TLSCipherText.version +
+             *     length_of( (IV +) ENC(...) ) +
+             *     IV + // except for TLS 1.0
+             *     ENC(content + padding + padding_length));
+             */
+            unsigned char pseudo_hdr[13];
+
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
+
+            memcpy( pseudo_hdr +  0, ssl->out_ctr, 8 );
+            memcpy( pseudo_hdr +  8, ssl->out_hdr, 3 );
+            pseudo_hdr[11] = (unsigned char)( ( ssl->out_msglen >> 8 ) & 0xFF );
+            pseudo_hdr[12] = (unsigned char)( ( ssl->out_msglen      ) & 0xFF );
+
+            MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", pseudo_hdr, 13 );
+
+            mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, pseudo_hdr, 13 );
+            mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc,
+                             ssl->out_iv, ssl->out_msglen );
+            mbedtls_md_hmac_finish( &ssl->transform_out->md_ctx_enc, mac );
+            mbedtls_md_hmac_reset( &ssl->transform_out->md_ctx_enc );
+
+            memcpy( ssl->out_iv + ssl->out_msglen, mac,
+                    ssl->transform_out->maclen );
+
+            ssl->out_msglen += ssl->transform_out->maclen;
+            auth_done++;
+        }
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
+    }
+    else
+#endif /* MBEDTLS_CIPHER_MODE_CBC &&
+          ( MBEDTLS_AES_C || MBEDTLS_CAMELLIA_C || MBEDTLS_ARIA_C ) */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    /* Make extra sure authentication was performed, exactly once */
+    if( auth_done != 1 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= encrypt buf" ) );
+
+    return( 0 );
+}
+
+static int ssl_decrypt_buf( mbedtls_ssl_context *ssl )
+{
+    mbedtls_cipher_mode_t mode;
+    int auth_done = 0;
+#if defined(SSL_SOME_MODES_USE_MAC)
+    size_t padlen = 0, correct = 1;
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> decrypt buf" ) );
+
+    if( ssl->session_in == NULL || ssl->transform_in == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    mode = mbedtls_cipher_get_cipher_mode( &ssl->transform_in->cipher_ctx_dec );
+
+    if( ssl->in_msglen < ssl->transform_in->minlen )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "in_msglen (%d) < minlen (%d)",
+                       ssl->in_msglen, ssl->transform_in->minlen ) );
+        return( MBEDTLS_ERR_SSL_INVALID_MAC );
+    }
+
+#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
+    if( mode == MBEDTLS_MODE_STREAM )
+    {
+        int ret;
+        size_t olen = 0;
+
+        padlen = 0;
+
+        if( ( ret = mbedtls_cipher_crypt( &ssl->transform_in->cipher_ctx_dec,
+                                   ssl->transform_in->iv_dec,
+                                   ssl->transform_in->ivlen,
+                                   ssl->in_msg, ssl->in_msglen,
+                                   ssl->in_msg, &olen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
+            return( ret );
+        }
+
+        if( ssl->in_msglen != olen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+    }
+    else
+#endif /* MBEDTLS_ARC4_C || MBEDTLS_CIPHER_NULL_CIPHER */
+#if defined(MBEDTLS_GCM_C) || \
+    defined(MBEDTLS_CCM_C) || \
+    defined(MBEDTLS_CHACHAPOLY_C)
+    if( mode == MBEDTLS_MODE_GCM ||
+        mode == MBEDTLS_MODE_CCM ||
+        mode == MBEDTLS_MODE_CHACHAPOLY )
+    {
+        int ret;
+        size_t dec_msglen, olen;
+        unsigned char *dec_msg;
+        unsigned char *dec_msg_result;
+        unsigned char add_data[13];
+        unsigned char iv[12];
+        mbedtls_ssl_transform *transform = ssl->transform_in;
+        unsigned char taglen = transform->ciphersuite_info->flags &
+                               MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16;
+        size_t explicit_iv_len = transform->ivlen - transform->fixed_ivlen;
+
+        /*
+         * Compute and update sizes
+         */
+        if( ssl->in_msglen < explicit_iv_len + taglen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) < explicit_iv_len (%d) "
+                                "+ taglen (%d)", ssl->in_msglen,
+                                explicit_iv_len, taglen ) );
+            return( MBEDTLS_ERR_SSL_INVALID_MAC );
+        }
+        dec_msglen = ssl->in_msglen - explicit_iv_len - taglen;
+
+        dec_msg = ssl->in_msg;
+        dec_msg_result = ssl->in_msg;
+        ssl->in_msglen = dec_msglen;
+
+        /*
+         * Prepare additional authenticated data
+         */
+        memcpy( add_data, ssl->in_ctr, 8 );
+        add_data[8]  = ssl->in_msgtype;
+        mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
+                           ssl->conf->transport, add_data + 9 );
+        add_data[11] = ( ssl->in_msglen >> 8 ) & 0xFF;
+        add_data[12] = ssl->in_msglen & 0xFF;
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "additional data for AEAD", add_data, 13 );
+
+        /*
+         * Prepare IV
+         */
+        if( transform->ivlen == 12 && transform->fixed_ivlen == 4 )
+        {
+            /* GCM and CCM: fixed || explicit (transmitted) */
+            memcpy( iv, transform->iv_dec, transform->fixed_ivlen );
+            memcpy( iv + transform->fixed_ivlen, ssl->in_iv, 8 );
+
+        }
+        else if( transform->ivlen == 12 && transform->fixed_ivlen == 12 )
+        {
+            /* ChachaPoly: fixed XOR sequence number */
+            unsigned char i;
+
+            memcpy( iv, transform->iv_dec, transform->fixed_ivlen );
+
+            for( i = 0; i < 8; i++ )
+                iv[i+4] ^= ssl->in_ctr[i];
+        }
+        else
+        {
+            /* Reminder if we ever add an AEAD mode with a different size */
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "IV used", iv, transform->ivlen );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "TAG used", dec_msg + dec_msglen, taglen );
+
+        /*
+         * Decrypt and authenticate
+         */
+        if( ( ret = mbedtls_cipher_auth_decrypt( &ssl->transform_in->cipher_ctx_dec,
+                                         iv, transform->ivlen,
+                                         add_data, 13,
+                                         dec_msg, dec_msglen,
+                                         dec_msg_result, &olen,
+                                         dec_msg + dec_msglen, taglen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_decrypt", ret );
+
+            if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED )
+                return( MBEDTLS_ERR_SSL_INVALID_MAC );
+
+            return( ret );
+        }
+        auth_done++;
+
+        if( olen != dec_msglen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+    }
+    else
+#endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
+#if defined(MBEDTLS_CIPHER_MODE_CBC) &&                                    \
+    ( defined(MBEDTLS_AES_C) || defined(MBEDTLS_CAMELLIA_C) || defined(MBEDTLS_ARIA_C) )
+    if( mode == MBEDTLS_MODE_CBC )
+    {
+        /*
+         * Decrypt and check the padding
+         */
+        int ret;
+        unsigned char *dec_msg;
+        unsigned char *dec_msg_result;
+        size_t dec_msglen;
+        size_t minlen = 0;
+        size_t olen = 0;
+
+        /*
+         * Check immediate ciphertext sanity
+         */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
+            minlen += ssl->transform_in->ivlen;
+#endif
+
+        if( ssl->in_msglen < minlen + ssl->transform_in->ivlen ||
+            ssl->in_msglen < minlen + ssl->transform_in->maclen + 1 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) < max( ivlen(%d), maclen (%d) "
+                                "+ 1 ) ( + expl IV )", ssl->in_msglen,
+                                ssl->transform_in->ivlen,
+                                ssl->transform_in->maclen ) );
+            return( MBEDTLS_ERR_SSL_INVALID_MAC );
+        }
+
+        dec_msglen = ssl->in_msglen;
+        dec_msg = ssl->in_msg;
+        dec_msg_result = ssl->in_msg;
+
+        /*
+         * Authenticate before decrypt if enabled
+         */
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+        if( ssl->session_in->encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED )
+        {
+            unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
+            unsigned char pseudo_hdr[13];
+
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
+
+            dec_msglen -= ssl->transform_in->maclen;
+            ssl->in_msglen -= ssl->transform_in->maclen;
+
+            memcpy( pseudo_hdr +  0, ssl->in_ctr, 8 );
+            memcpy( pseudo_hdr +  8, ssl->in_hdr, 3 );
+            pseudo_hdr[11] = (unsigned char)( ( ssl->in_msglen >> 8 ) & 0xFF );
+            pseudo_hdr[12] = (unsigned char)( ( ssl->in_msglen      ) & 0xFF );
+
+            MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", pseudo_hdr, 13 );
+
+            mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, pseudo_hdr, 13 );
+            mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec,
+                             ssl->in_iv, ssl->in_msglen );
+            mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec, mac_expect );
+            mbedtls_md_hmac_reset( &ssl->transform_in->md_ctx_dec );
+
+            MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", ssl->in_iv + ssl->in_msglen,
+                                              ssl->transform_in->maclen );
+            MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect,
+                                              ssl->transform_in->maclen );
+
+            if( mbedtls_ssl_safer_memcmp( ssl->in_iv + ssl->in_msglen, mac_expect,
+                                          ssl->transform_in->maclen ) != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
+
+                return( MBEDTLS_ERR_SSL_INVALID_MAC );
+            }
+            auth_done++;
+        }
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
+
+        /*
+         * Check length sanity
+         */
+        if( ssl->in_msglen % ssl->transform_in->ivlen != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) %% ivlen (%d) != 0",
+                           ssl->in_msglen, ssl->transform_in->ivlen ) );
+            return( MBEDTLS_ERR_SSL_INVALID_MAC );
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        /*
+         * Initialize for prepended IV for block cipher in TLS v1.1 and up
+         */
+        if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
+        {
+            unsigned char i;
+            dec_msglen -= ssl->transform_in->ivlen;
+            ssl->in_msglen -= ssl->transform_in->ivlen;
+
+            for( i = 0; i < ssl->transform_in->ivlen; i++ )
+                ssl->transform_in->iv_dec[i] = ssl->in_iv[i];
+        }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
+
+        if( ( ret = mbedtls_cipher_crypt( &ssl->transform_in->cipher_ctx_dec,
+                                   ssl->transform_in->iv_dec,
+                                   ssl->transform_in->ivlen,
+                                   dec_msg, dec_msglen,
+                                   dec_msg_result, &olen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
+            return( ret );
+        }
+
+        if( dec_msglen != olen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1)
+        if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 )
+        {
+            /*
+             * Save IV in SSL3 and TLS1
+             */
+            memcpy( ssl->transform_in->iv_dec,
+                    ssl->transform_in->cipher_ctx_dec.iv,
+                    ssl->transform_in->ivlen );
+        }
+#endif
+
+        padlen = 1 + ssl->in_msg[ssl->in_msglen - 1];
+
+        if( ssl->in_msglen < ssl->transform_in->maclen + padlen &&
+            auth_done == 0 )
+        {
+#if defined(MBEDTLS_SSL_DEBUG_ALL)
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) < maclen (%d) + padlen (%d)",
+                        ssl->in_msglen, ssl->transform_in->maclen, padlen ) );
+#endif
+            padlen = 0;
+            correct = 0;
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+        {
+            if( padlen > ssl->transform_in->ivlen )
+            {
+#if defined(MBEDTLS_SSL_DEBUG_ALL)
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad padding length: is %d, "
+                                    "should be no more than %d",
+                               padlen, ssl->transform_in->ivlen ) );
+#endif
+                correct = 0;
+            }
+        }
+        else
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( ssl->minor_ver > MBEDTLS_SSL_MINOR_VERSION_0 )
+        {
+            /*
+             * TLSv1+: always check the padding up to the first failure
+             * and fake check up to 256 bytes of padding
+             */
+            size_t pad_count = 0, real_count = 1;
+            size_t padding_idx = ssl->in_msglen - padlen;
+            size_t i;
+
+            /*
+             * Padding is guaranteed to be incorrect if:
+             *   1. padlen > ssl->in_msglen
+             *
+             *   2. padding_idx > MBEDTLS_SSL_IN_CONTENT_LEN +
+             *                     ssl->transform_in->maclen
+             *
+             * In both cases we reset padding_idx to a safe value (0) to
+             * prevent out-of-buffer reads.
+             */
+            correct &= ( padlen <= ssl->in_msglen );
+            correct &= ( padding_idx <= MBEDTLS_SSL_IN_CONTENT_LEN +
+                                       ssl->transform_in->maclen );
+
+            padding_idx *= correct;
+
+            for( i = 0; i < 256; i++ )
+            {
+                real_count &= ( i < padlen );
+                pad_count += real_count *
+                             ( ssl->in_msg[padding_idx + i] == padlen - 1 );
+            }
+
+            correct &= ( pad_count == padlen ); /* Only 1 on correct padding */
+
+#if defined(MBEDTLS_SSL_DEBUG_ALL)
+            if( padlen > 0 && correct == 0 )
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad padding byte detected" ) );
+#endif
+            padlen &= correct * 0x1FF;
+        }
+        else
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
+          MBEDTLS_SSL_PROTO_TLS1_2 */
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        ssl->in_msglen -= padlen;
+    }
+    else
+#endif /* MBEDTLS_CIPHER_MODE_CBC &&
+          ( MBEDTLS_AES_C || MBEDTLS_CAMELLIA_C || MBEDTLS_ARIA_C ) */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+#if defined(MBEDTLS_SSL_DEBUG_ALL)
+    MBEDTLS_SSL_DEBUG_BUF( 4, "raw buffer after decryption",
+                   ssl->in_msg, ssl->in_msglen );
+#endif
+
+    /*
+     * Authenticate if not done yet.
+     * Compute the MAC regardless of the padding result (RFC4346, CBCTIME).
+     */
+#if defined(SSL_SOME_MODES_USE_MAC)
+    if( auth_done == 0 )
+    {
+        unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
+
+        ssl->in_msglen -= ssl->transform_in->maclen;
+
+        ssl->in_len[0] = (unsigned char)( ssl->in_msglen >> 8 );
+        ssl->in_len[1] = (unsigned char)( ssl->in_msglen      );
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+        {
+            ssl_mac( &ssl->transform_in->md_ctx_dec,
+                      ssl->transform_in->mac_dec,
+                      ssl->in_msg, ssl->in_msglen,
+                      ssl->in_ctr, ssl->in_msgtype,
+                      mac_expect );
+        }
+        else
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+        defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( ssl->minor_ver > MBEDTLS_SSL_MINOR_VERSION_0 )
+        {
+            /*
+             * Process MAC and always update for padlen afterwards to make
+             * total time independent of padlen.
+             *
+             * Known timing attacks:
+             *  - Lucky Thirteen (http://www.isg.rhul.ac.uk/tls/TLStiming.pdf)
+             *
+             * To compensate for different timings for the MAC calculation
+             * depending on how much padding was removed (which is determined
+             * by padlen), process extra_run more blocks through the hash
+             * function.
+             *
+             * The formula in the paper is
+             *   extra_run = ceil( (L1-55) / 64 ) - ceil( (L2-55) / 64 )
+             * where L1 is the size of the header plus the decrypted message
+             * plus CBC padding and L2 is the size of the header plus the
+             * decrypted message. This is for an underlying hash function
+             * with 64-byte blocks.
+             * We use ( (Lx+8) / 64 ) to handle 'negative Lx' values
+             * correctly. We round down instead of up, so -56 is the correct
+             * value for our calculations instead of -55.
+             *
+             * Repeat the formula rather than defining a block_size variable.
+             * This avoids requiring division by a variable at runtime
+             * (which would be marginally less efficient and would require
+             * linking an extra division function in some builds).
+             */
+            size_t j, extra_run = 0;
+
+            /*
+             * The next two sizes are the minimum and maximum values of
+             * in_msglen over all padlen values.
+             *
+             * They're independent of padlen, since we previously did
+             * in_msglen -= padlen.
+             *
+             * Note that max_len + maclen is never more than the buffer
+             * length, as we previously did in_msglen -= maclen too.
+             */
+            const size_t max_len = ssl->in_msglen + padlen;
+            const size_t min_len = ( max_len > 256 ) ? max_len - 256 : 0;
+
+            switch( ssl->transform_in->ciphersuite_info->mac )
+            {
+#if defined(MBEDTLS_MD5_C) || defined(MBEDTLS_SHA1_C) || \
+    defined(MBEDTLS_SHA256_C)
+                case MBEDTLS_MD_MD5:
+                case MBEDTLS_MD_SHA1:
+                case MBEDTLS_MD_SHA256:
+                    /* 8 bytes of message size, 64-byte compression blocks */
+                    extra_run = ( 13 + ssl->in_msglen + padlen + 8 ) / 64 -
+                                ( 13 + ssl->in_msglen          + 8 ) / 64;
+                    break;
+#endif
+#if defined(MBEDTLS_SHA512_C)
+                case MBEDTLS_MD_SHA384:
+                    /* 16 bytes of message size, 128-byte compression blocks */
+                    extra_run = ( 13 + ssl->in_msglen + padlen + 16 ) / 128 -
+                                ( 13 + ssl->in_msglen          + 16 ) / 128;
+                    break;
+#endif
+                default:
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+                    return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+            }
+
+            extra_run &= correct * 0xFF;
+
+            mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_ctr, 8 );
+            mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_hdr, 3 );
+            mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_len, 2 );
+            mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_msg,
+                             ssl->in_msglen );
+            /* Make sure we access everything even when padlen > 0. This
+             * makes the synchronisation requirements for just-in-time
+             * Prime+Probe attacks much tighter and hopefully impractical. */
+            ssl_read_memory( ssl->in_msg + ssl->in_msglen, padlen );
+            mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec, mac_expect );
+
+            /* Call mbedtls_md_process at least once due to cache attacks
+             * that observe whether md_process() was called of not */
+            for( j = 0; j < extra_run + 1; j++ )
+                mbedtls_md_process( &ssl->transform_in->md_ctx_dec, ssl->in_msg );
+
+            mbedtls_md_hmac_reset( &ssl->transform_in->md_ctx_dec );
+
+            /* Make sure we access all the memory that could contain the MAC,
+             * before we check it in the next code block. This makes the
+             * synchronisation requirements for just-in-time Prime+Probe
+             * attacks much tighter and hopefully impractical. */
+            ssl_read_memory( ssl->in_msg + min_len,
+                                 max_len - min_len + ssl->transform_in->maclen );
+        }
+        else
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
+              MBEDTLS_SSL_PROTO_TLS1_2 */
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+#if defined(MBEDTLS_SSL_DEBUG_ALL)
+        MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect, ssl->transform_in->maclen );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", ssl->in_msg + ssl->in_msglen,
+                               ssl->transform_in->maclen );
+#endif
+
+        if( mbedtls_ssl_safer_memcmp( ssl->in_msg + ssl->in_msglen, mac_expect,
+                                      ssl->transform_in->maclen ) != 0 )
+        {
+#if defined(MBEDTLS_SSL_DEBUG_ALL)
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
+#endif
+            correct = 0;
+        }
+        auth_done++;
+    }
+
+    /*
+     * Finally check the correct flag
+     */
+    if( correct == 0 )
+        return( MBEDTLS_ERR_SSL_INVALID_MAC );
+#endif /* SSL_SOME_MODES_USE_MAC */
+
+    /* Make extra sure authentication was performed, exactly once */
+    if( auth_done != 1 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    if( ssl->in_msglen == 0 )
+    {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3
+            && ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
+        {
+            /* TLS v1.2 explicitly disallows zero-length messages which are not application data */
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid zero-length message type: %d", ssl->in_msgtype ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+        ssl->nb_zero++;
+
+        /*
+         * Three or more empty messages may be a DoS attack
+         * (excessive CPU consumption).
+         */
+        if( ssl->nb_zero > 3 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "received four consecutive empty "
+                                "messages, possible DoS attack" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_MAC );
+        }
+    }
+    else
+        ssl->nb_zero = 0;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        ; /* in_ctr read from peer, not maintained internally */
+    }
+    else
+#endif
+    {
+        unsigned char i;
+        for( i = 8; i > ssl_ep_len( ssl ); i-- )
+            if( ++ssl->in_ctr[i - 1] != 0 )
+                break;
+
+        /* The loop goes to its end iff the counter is wrapping */
+        if( i == ssl_ep_len( ssl ) )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "incoming message counter would wrap" ) );
+            return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
+        }
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= decrypt buf" ) );
+
+    return( 0 );
+}
+
+#undef MAC_NONE
+#undef MAC_PLAINTEXT
+#undef MAC_CIPHERTEXT
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+/*
+ * Compression/decompression functions
+ */
+static int ssl_compress_buf( mbedtls_ssl_context *ssl )
+{
+    int ret;
+    unsigned char *msg_post = ssl->out_msg;
+    ptrdiff_t bytes_written = ssl->out_msg - ssl->out_buf;
+    size_t len_pre = ssl->out_msglen;
+    unsigned char *msg_pre = ssl->compress_buf;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> compress buf" ) );
+
+    if( len_pre == 0 )
+        return( 0 );
+
+    memcpy( msg_pre, ssl->out_msg, len_pre );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "before compression: msglen = %d, ",
+                   ssl->out_msglen ) );
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "before compression: output payload",
+                   ssl->out_msg, ssl->out_msglen );
+
+    ssl->transform_out->ctx_deflate.next_in = msg_pre;
+    ssl->transform_out->ctx_deflate.avail_in = len_pre;
+    ssl->transform_out->ctx_deflate.next_out = msg_post;
+    ssl->transform_out->ctx_deflate.avail_out = MBEDTLS_SSL_OUT_BUFFER_LEN - bytes_written;
+
+    ret = deflate( &ssl->transform_out->ctx_deflate, Z_SYNC_FLUSH );
+    if( ret != Z_OK )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "failed to perform compression (%d)", ret ) );
+        return( MBEDTLS_ERR_SSL_COMPRESSION_FAILED );
+    }
+
+    ssl->out_msglen = MBEDTLS_SSL_OUT_BUFFER_LEN -
+                      ssl->transform_out->ctx_deflate.avail_out - bytes_written;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "after compression: msglen = %d, ",
+                   ssl->out_msglen ) );
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "after compression: output payload",
+                   ssl->out_msg, ssl->out_msglen );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= compress buf" ) );
+
+    return( 0 );
+}
+
+static int ssl_decompress_buf( mbedtls_ssl_context *ssl )
+{
+    int ret;
+    unsigned char *msg_post = ssl->in_msg;
+    ptrdiff_t header_bytes = ssl->in_msg - ssl->in_buf;
+    size_t len_pre = ssl->in_msglen;
+    unsigned char *msg_pre = ssl->compress_buf;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> decompress buf" ) );
+
+    if( len_pre == 0 )
+        return( 0 );
+
+    memcpy( msg_pre, ssl->in_msg, len_pre );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "before decompression: msglen = %d, ",
+                   ssl->in_msglen ) );
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "before decompression: input payload",
+                   ssl->in_msg, ssl->in_msglen );
+
+    ssl->transform_in->ctx_inflate.next_in = msg_pre;
+    ssl->transform_in->ctx_inflate.avail_in = len_pre;
+    ssl->transform_in->ctx_inflate.next_out = msg_post;
+    ssl->transform_in->ctx_inflate.avail_out = MBEDTLS_SSL_IN_BUFFER_LEN -
+                                               header_bytes;
+
+    ret = inflate( &ssl->transform_in->ctx_inflate, Z_SYNC_FLUSH );
+    if( ret != Z_OK )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "failed to perform decompression (%d)", ret ) );
+        return( MBEDTLS_ERR_SSL_COMPRESSION_FAILED );
+    }
+
+    ssl->in_msglen = MBEDTLS_SSL_IN_BUFFER_LEN -
+                     ssl->transform_in->ctx_inflate.avail_out - header_bytes;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "after decompression: msglen = %d, ",
+                   ssl->in_msglen ) );
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "after decompression: input payload",
+                   ssl->in_msg, ssl->in_msglen );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= decompress buf" ) );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_ZLIB_SUPPORT */
+
+#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
+static int ssl_write_hello_request( mbedtls_ssl_context *ssl );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+static int ssl_resend_hello_request( mbedtls_ssl_context *ssl )
+{
+    /* If renegotiation is not enforced, retransmit until we would reach max
+     * timeout if we were using the usual handshake doubling scheme */
+    if( ssl->conf->renego_max_records < 0 )
+    {
+        uint32_t ratio = ssl->conf->hs_timeout_max / ssl->conf->hs_timeout_min + 1;
+        unsigned char doublings = 1;
+
+        while( ratio != 0 )
+        {
+            ++doublings;
+            ratio >>= 1;
+        }
+
+        if( ++ssl->renego_records_seen > doublings )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "no longer retransmitting hello request" ) );
+            return( 0 );
+        }
+    }
+
+    return( ssl_write_hello_request( ssl ) );
+}
+#endif
+#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
+
+/*
+ * Fill the input message buffer by appending data to it.
+ * The amount of data already fetched is in ssl->in_left.
+ *
+ * If we return 0, is it guaranteed that (at least) nb_want bytes are
+ * available (from this read and/or a previous one). Otherwise, an error code
+ * is returned (possibly EOF or WANT_READ).
+ *
+ * With stream transport (TLS) on success ssl->in_left == nb_want, but
+ * with datagram transport (DTLS) on success ssl->in_left >= nb_want,
+ * since we always read a whole datagram at once.
+ *
+ * For DTLS, it is up to the caller to set ssl->next_record_offset when
+ * they're done reading a record.
+ */
+int mbedtls_ssl_fetch_input( mbedtls_ssl_context *ssl, size_t nb_want )
+{
+    int ret;
+    size_t len;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> fetch input" ) );
+
+    if( ssl->f_recv == NULL && ssl->f_recv_timeout == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
+                            "or mbedtls_ssl_set_bio()" ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    if( nb_want > MBEDTLS_SSL_IN_BUFFER_LEN - (size_t)( ssl->in_hdr - ssl->in_buf ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "requesting more data than fits" ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        uint32_t timeout;
+
+        /* Just to be sure */
+        if( ssl->f_set_timer == NULL || ssl->f_get_timer == NULL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "You must use "
+                        "mbedtls_ssl_set_timer_cb() for DTLS" ) );
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+        }
+
+        /*
+         * The point is, we need to always read a full datagram at once, so we
+         * sometimes read more then requested, and handle the additional data.
+         * It could be the rest of the current record (while fetching the
+         * header) and/or some other records in the same datagram.
+         */
+
+        /*
+         * Move to the next record in the already read datagram if applicable
+         */
+        if( ssl->next_record_offset != 0 )
+        {
+            if( ssl->in_left < ssl->next_record_offset )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+                return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+            }
+
+            ssl->in_left -= ssl->next_record_offset;
+
+            if( ssl->in_left != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "next record in same datagram, offset: %d",
+                                    ssl->next_record_offset ) );
+                memmove( ssl->in_hdr,
+                         ssl->in_hdr + ssl->next_record_offset,
+                         ssl->in_left );
+            }
+
+            ssl->next_record_offset = 0;
+        }
+
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %d, nb_want: %d",
+                       ssl->in_left, nb_want ) );
+
+        /*
+         * Done if we already have enough data.
+         */
+        if( nb_want <= ssl->in_left)
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
+            return( 0 );
+        }
+
+        /*
+         * A record can't be split across datagrams. If we need to read but
+         * are not at the beginning of a new record, the caller did something
+         * wrong.
+         */
+        if( ssl->in_left != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        /*
+         * Don't even try to read if time's out already.
+         * This avoids by-passing the timer when repeatedly receiving messages
+         * that will end up being dropped.
+         */
+        if( ssl_check_timer( ssl ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "timer has expired" ) );
+            ret = MBEDTLS_ERR_SSL_TIMEOUT;
+        }
+        else
+        {
+            len = MBEDTLS_SSL_IN_BUFFER_LEN - ( ssl->in_hdr - ssl->in_buf );
+
+            if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+                timeout = ssl->handshake->retransmit_timeout;
+            else
+                timeout = ssl->conf->read_timeout;
+
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "f_recv_timeout: %u ms", timeout ) );
+
+            if( ssl->f_recv_timeout != NULL )
+                ret = ssl->f_recv_timeout( ssl->p_bio, ssl->in_hdr, len,
+                                                                    timeout );
+            else
+                ret = ssl->f_recv( ssl->p_bio, ssl->in_hdr, len );
+
+            MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
+
+            if( ret == 0 )
+                return( MBEDTLS_ERR_SSL_CONN_EOF );
+        }
+
+        if( ret == MBEDTLS_ERR_SSL_TIMEOUT )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "timeout" ) );
+            ssl_set_timer( ssl, 0 );
+
+            if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+            {
+                if( ssl_double_retransmit_timeout( ssl ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake timeout" ) );
+                    return( MBEDTLS_ERR_SSL_TIMEOUT );
+                }
+
+                if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
+                    return( ret );
+                }
+
+                return( MBEDTLS_ERR_SSL_WANT_READ );
+            }
+#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
+            else if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
+                     ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
+            {
+                if( ( ret = ssl_resend_hello_request( ssl ) ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_RET( 1, "ssl_resend_hello_request", ret );
+                    return( ret );
+                }
+
+                return( MBEDTLS_ERR_SSL_WANT_READ );
+            }
+#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
+        }
+
+        if( ret < 0 )
+            return( ret );
+
+        ssl->in_left = ret;
+    }
+    else
+#endif
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %d, nb_want: %d",
+                       ssl->in_left, nb_want ) );
+
+        while( ssl->in_left < nb_want )
+        {
+            len = nb_want - ssl->in_left;
+
+            if( ssl_check_timer( ssl ) != 0 )
+                ret = MBEDTLS_ERR_SSL_TIMEOUT;
+            else
+            {
+                if( ssl->f_recv_timeout != NULL )
+                {
+                    ret = ssl->f_recv_timeout( ssl->p_bio,
+                                               ssl->in_hdr + ssl->in_left, len,
+                                               ssl->conf->read_timeout );
+                }
+                else
+                {
+                    ret = ssl->f_recv( ssl->p_bio,
+                                       ssl->in_hdr + ssl->in_left, len );
+                }
+            }
+
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %d, nb_want: %d",
+                                        ssl->in_left, nb_want ) );
+            MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
+
+            if( ret == 0 )
+                return( MBEDTLS_ERR_SSL_CONN_EOF );
+
+            if( ret < 0 )
+                return( ret );
+
+            if ( (size_t)ret > len || ( INT_MAX > SIZE_MAX && ret > SIZE_MAX ) )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1,
+                    ( "f_recv returned %d bytes but only %lu were requested",
+                    ret, (unsigned long)len ) );
+                return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+            }
+
+            ssl->in_left += ret;
+        }
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
+
+    return( 0 );
+}
+
+/*
+ * Flush any data not yet written
+ */
+int mbedtls_ssl_flush_output( mbedtls_ssl_context *ssl )
+{
+    int ret;
+    unsigned char *buf;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> flush output" ) );
+
+    if( ssl->f_send == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
+                            "or mbedtls_ssl_set_bio()" ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    /* Avoid incrementing counter if data is flushed */
+    if( ssl->out_left == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
+        return( 0 );
+    }
+
+    while( ssl->out_left > 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "message length: %d, out_left: %d",
+                       mbedtls_ssl_hdr_len( ssl ) + ssl->out_msglen, ssl->out_left ) );
+
+        buf = ssl->out_hdr - ssl->out_left;
+        ret = ssl->f_send( ssl->p_bio, buf, ssl->out_left );
+
+        MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_send", ret );
+
+        if( ret <= 0 )
+            return( ret );
+
+        if( (size_t)ret > ssl->out_left || ( INT_MAX > SIZE_MAX && ret > SIZE_MAX ) )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1,
+                ( "f_send returned %d bytes but only %lu bytes were sent",
+                ret, (unsigned long)ssl->out_left ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        ssl->out_left -= ret;
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        ssl->out_hdr = ssl->out_buf;
+    }
+    else
+#endif
+    {
+        ssl->out_hdr = ssl->out_buf + 8;
+    }
+    ssl_update_out_pointers( ssl, ssl->transform_out );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
+
+    return( 0 );
+}
+
+/*
+ * Functions to handle the DTLS retransmission state machine
+ */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+/*
+ * Append current handshake message to current outgoing flight
+ */
+static int ssl_flight_append( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_flight_item *msg;
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_flight_append" ) );
+    MBEDTLS_SSL_DEBUG_BUF( 4, "message appended to flight",
+                           ssl->out_msg, ssl->out_msglen );
+
+    /* Allocate space for current message */
+    if( ( msg = mbedtls_calloc( 1, sizeof(  mbedtls_ssl_flight_item ) ) ) == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %d bytes failed",
+                            sizeof( mbedtls_ssl_flight_item ) ) );
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+
+    if( ( msg->p = mbedtls_calloc( 1, ssl->out_msglen ) ) == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %d bytes failed", ssl->out_msglen ) );
+        mbedtls_free( msg );
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+
+    /* Copy current handshake message with headers */
+    memcpy( msg->p, ssl->out_msg, ssl->out_msglen );
+    msg->len = ssl->out_msglen;
+    msg->type = ssl->out_msgtype;
+    msg->next = NULL;
+
+    /* Append to the current flight */
+    if( ssl->handshake->flight == NULL )
+        ssl->handshake->flight = msg;
+    else
+    {
+        mbedtls_ssl_flight_item *cur = ssl->handshake->flight;
+        while( cur->next != NULL )
+            cur = cur->next;
+        cur->next = msg;
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_flight_append" ) );
+    return( 0 );
+}
+
+/*
+ * Free the current flight of handshake messages
+ */
+static void ssl_flight_free( mbedtls_ssl_flight_item *flight )
+{
+    mbedtls_ssl_flight_item *cur = flight;
+    mbedtls_ssl_flight_item *next;
+
+    while( cur != NULL )
+    {
+        next = cur->next;
+
+        mbedtls_free( cur->p );
+        mbedtls_free( cur );
+
+        cur = next;
+    }
+}
+
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+static void ssl_dtls_replay_reset( mbedtls_ssl_context *ssl );
+#endif
+
+/*
+ * Swap transform_out and out_ctr with the alternative ones
+ */
+static void ssl_swap_epochs( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_transform *tmp_transform;
+    unsigned char tmp_out_ctr[8];
+
+    if( ssl->transform_out == ssl->handshake->alt_transform_out )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip swap epochs" ) );
+        return;
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "swap epochs" ) );
+
+    /* Swap transforms */
+    tmp_transform                     = ssl->transform_out;
+    ssl->transform_out                = ssl->handshake->alt_transform_out;
+    ssl->handshake->alt_transform_out = tmp_transform;
+
+    /* Swap epoch + sequence_number */
+    memcpy( tmp_out_ctr,                 ssl->cur_out_ctr,            8 );
+    memcpy( ssl->cur_out_ctr,            ssl->handshake->alt_out_ctr, 8 );
+    memcpy( ssl->handshake->alt_out_ctr, tmp_out_ctr,                 8 );
+
+    /* Adjust to the newly activated transform */
+    ssl_update_out_pointers( ssl, ssl->transform_out );
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_activate != NULL )
+    {
+        if( ( ret = mbedtls_ssl_hw_record_activate( ssl, MBEDTLS_SSL_CHANNEL_OUTBOUND ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_activate", ret );
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+    }
+#endif
+}
+
+/*
+ * Retransmit the current flight of messages.
+ */
+int mbedtls_ssl_resend( mbedtls_ssl_context *ssl )
+{
+    int ret = 0;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_resend" ) );
+
+    ret = mbedtls_ssl_flight_transmit( ssl );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_resend" ) );
+
+    return( ret );
+}
+
+/*
+ * Transmit or retransmit the current flight of messages.
+ *
+ * Need to remember the current message in case flush_output returns
+ * WANT_WRITE, causing us to exit this function and come back later.
+ * This function must be called until state is no longer SENDING.
+ */
+int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
+{
+    int ret;
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_flight_transmit" ) );
+
+    if( ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialise flight transmission" ) );
+
+        ssl->handshake->cur_msg = ssl->handshake->flight;
+        ssl->handshake->cur_msg_p = ssl->handshake->flight->p + 12;
+        ssl_swap_epochs( ssl );
+
+        ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_SENDING;
+    }
+
+    while( ssl->handshake->cur_msg != NULL )
+    {
+        size_t max_frag_len;
+        const mbedtls_ssl_flight_item * const cur = ssl->handshake->cur_msg;
+
+        int const is_finished =
+            ( cur->type == MBEDTLS_SSL_MSG_HANDSHAKE &&
+              cur->p[0] == MBEDTLS_SSL_HS_FINISHED );
+
+        uint8_t const force_flush = ssl->disable_datagram_packing == 1 ?
+            SSL_FORCE_FLUSH : SSL_DONT_FORCE_FLUSH;
+
+        /* Swap epochs before sending Finished: we can't do it after
+         * sending ChangeCipherSpec, in case write returns WANT_READ.
+         * Must be done before copying, may change out_msg pointer */
+        if( is_finished && ssl->handshake->cur_msg_p == ( cur->p + 12 ) )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "swap epochs to send finished message" ) );
+            ssl_swap_epochs( ssl );
+        }
+
+        ret = ssl_get_remaining_payload_in_datagram( ssl );
+        if( ret < 0 )
+            return( ret );
+        max_frag_len = (size_t) ret;
+
+        /* CCS is copied as is, while HS messages may need fragmentation */
+        if( cur->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
+        {
+            if( max_frag_len == 0 )
+            {
+                if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+                    return( ret );
+
+                continue;
+            }
+
+            memcpy( ssl->out_msg, cur->p, cur->len );
+            ssl->out_msglen  = cur->len;
+            ssl->out_msgtype = cur->type;
+
+            /* Update position inside current message */
+            ssl->handshake->cur_msg_p += cur->len;
+        }
+        else
+        {
+            const unsigned char * const p = ssl->handshake->cur_msg_p;
+            const size_t hs_len = cur->len - 12;
+            const size_t frag_off = p - ( cur->p + 12 );
+            const size_t rem_len = hs_len - frag_off;
+            size_t cur_hs_frag_len, max_hs_frag_len;
+
+            if( ( max_frag_len < 12 ) || ( max_frag_len == 12 && hs_len != 0 ) )
+            {
+                if( is_finished )
+                    ssl_swap_epochs( ssl );
+
+                if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+                    return( ret );
+
+                continue;
+            }
+            max_hs_frag_len = max_frag_len - 12;
+
+            cur_hs_frag_len = rem_len > max_hs_frag_len ?
+                max_hs_frag_len : rem_len;
+
+            if( frag_off == 0 && cur_hs_frag_len != hs_len )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "fragmenting handshake message (%u > %u)",
+                                            (unsigned) cur_hs_frag_len,
+                                            (unsigned) max_hs_frag_len ) );
+            }
+
+            /* Messages are stored with handshake headers as if not fragmented,
+             * copy beginning of headers then fill fragmentation fields.
+             * Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */
+            memcpy( ssl->out_msg, cur->p, 6 );
+
+            ssl->out_msg[6] = ( ( frag_off >> 16 ) & 0xff );
+            ssl->out_msg[7] = ( ( frag_off >>  8 ) & 0xff );
+            ssl->out_msg[8] = ( ( frag_off       ) & 0xff );
+
+            ssl->out_msg[ 9] = ( ( cur_hs_frag_len >> 16 ) & 0xff );
+            ssl->out_msg[10] = ( ( cur_hs_frag_len >>  8 ) & 0xff );
+            ssl->out_msg[11] = ( ( cur_hs_frag_len       ) & 0xff );
+
+            MBEDTLS_SSL_DEBUG_BUF( 3, "handshake header", ssl->out_msg, 12 );
+
+            /* Copy the handshake message content and set records fields */
+            memcpy( ssl->out_msg + 12, p, cur_hs_frag_len );
+            ssl->out_msglen = cur_hs_frag_len + 12;
+            ssl->out_msgtype = cur->type;
+
+            /* Update position inside current message */
+            ssl->handshake->cur_msg_p += cur_hs_frag_len;
+        }
+
+        /* If done with the current message move to the next one if any */
+        if( ssl->handshake->cur_msg_p >= cur->p + cur->len )
+        {
+            if( cur->next != NULL )
+            {
+                ssl->handshake->cur_msg = cur->next;
+                ssl->handshake->cur_msg_p = cur->next->p + 12;
+            }
+            else
+            {
+                ssl->handshake->cur_msg = NULL;
+                ssl->handshake->cur_msg_p = NULL;
+            }
+        }
+
+        /* Actually send the message out */
+        if( ( ret = mbedtls_ssl_write_record( ssl, force_flush ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
+            return( ret );
+        }
+    }
+
+    if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+        return( ret );
+
+    /* Update state and set timer */
+    if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
+        ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
+    else
+    {
+        ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
+        ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_flight_transmit" ) );
+
+    return( 0 );
+}
+
+/*
+ * To be called when the last message of an incoming flight is received.
+ */
+void mbedtls_ssl_recv_flight_completed( mbedtls_ssl_context *ssl )
+{
+    /* We won't need to resend that one any more */
+    ssl_flight_free( ssl->handshake->flight );
+    ssl->handshake->flight = NULL;
+    ssl->handshake->cur_msg = NULL;
+
+    /* The next incoming flight will start with this msg_seq */
+    ssl->handshake->in_flight_start_seq = ssl->handshake->in_msg_seq;
+
+    /* We don't want to remember CCS's across flight boundaries. */
+    ssl->handshake->buffering.seen_ccs = 0;
+
+    /* Clear future message buffering structure. */
+    ssl_buffering_free( ssl );
+
+    /* Cancel timer */
+    ssl_set_timer( ssl, 0 );
+
+    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
+        ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
+    {
+        ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
+    }
+    else
+        ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
+}
+
+/*
+ * To be called when the last message of an outgoing flight is send.
+ */
+void mbedtls_ssl_send_flight_completed( mbedtls_ssl_context *ssl )
+{
+    ssl_reset_retransmit_timeout( ssl );
+    ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
+
+    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
+        ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
+    {
+        ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
+    }
+    else
+        ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
+}
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+/*
+ * Handshake layer functions
+ */
+
+/*
+ * Write (DTLS: or queue) current handshake (including CCS) message.
+ *
+ *  - fill in handshake headers
+ *  - update handshake checksum
+ *  - DTLS: save message for resending
+ *  - then pass to the record layer
+ *
+ * DTLS: except for HelloRequest, messages are only queued, and will only be
+ * actually sent when calling flight_transmit() or resend().
+ *
+ * Inputs:
+ *  - ssl->out_msglen: 4 + actual handshake message len
+ *      (4 is the size of handshake headers for TLS)
+ *  - ssl->out_msg[0]: the handshake type (ClientHello, ServerHello, etc)
+ *  - ssl->out_msg + 4: the handshake message body
+ *
+ * Outputs, ie state before passing to flight_append() or write_record():
+ *   - ssl->out_msglen: the length of the record contents
+ *      (including handshake headers but excluding record headers)
+ *   - ssl->out_msg: the record contents (handshake headers + content)
+ */
+int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
+{
+    int ret;
+    const size_t hs_len = ssl->out_msglen - 4;
+    const unsigned char hs_type = ssl->out_msg[0];
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write handshake message" ) );
+
+    /*
+     * Sanity checks
+     */
+    if( ssl->out_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE          &&
+        ssl->out_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
+    {
+        /* In SSLv3, the client might send a NoCertificate alert. */
+#if defined(MBEDTLS_SSL_PROTO_SSL3) && defined(MBEDTLS_SSL_CLI_C)
+        if( ! ( ssl->minor_ver      == MBEDTLS_SSL_MINOR_VERSION_0 &&
+                ssl->out_msgtype    == MBEDTLS_SSL_MSG_ALERT       &&
+                ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT ) )
+#endif /* MBEDTLS_SSL_PROTO_SSL3 && MBEDTLS_SSL_SRV_C */
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+    }
+
+    /* Whenever we send anything different from a
+     * HelloRequest we should be in a handshake - double check. */
+    if( ! ( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
+            hs_type          == MBEDTLS_SSL_HS_HELLO_REQUEST ) &&
+        ssl->handshake == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake != NULL &&
+        ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+#endif
+
+    /* Double-check that we did not exceed the bounds
+     * of the outgoing record buffer.
+     * This should never fail as the various message
+     * writing functions must obey the bounds of the
+     * outgoing record buffer, but better be safe.
+     *
+     * Note: We deliberately do not check for the MTU or MFL here.
+     */
+    if( ssl->out_msglen > MBEDTLS_SSL_OUT_CONTENT_LEN )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Record too large: "
+                                    "size %u, maximum %u",
+                                    (unsigned) ssl->out_msglen,
+                                    (unsigned) MBEDTLS_SSL_OUT_CONTENT_LEN ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    /*
+     * Fill handshake headers
+     */
+    if( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        ssl->out_msg[1] = (unsigned char)( hs_len >> 16 );
+        ssl->out_msg[2] = (unsigned char)( hs_len >>  8 );
+        ssl->out_msg[3] = (unsigned char)( hs_len       );
+
+        /*
+         * DTLS has additional fields in the Handshake layer,
+         * between the length field and the actual payload:
+         *      uint16 message_seq;
+         *      uint24 fragment_offset;
+         *      uint24 fragment_length;
+         */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        {
+            /* Make room for the additional DTLS fields */
+            if( MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen < 8 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS handshake message too large: "
+                              "size %u, maximum %u",
+                               (unsigned) ( hs_len ),
+                               (unsigned) ( MBEDTLS_SSL_OUT_CONTENT_LEN - 12 ) ) );
+                return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+            }
+
+            memmove( ssl->out_msg + 12, ssl->out_msg + 4, hs_len );
+            ssl->out_msglen += 8;
+
+            /* Write message_seq and update it, except for HelloRequest */
+            if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
+            {
+                ssl->out_msg[4] = ( ssl->handshake->out_msg_seq >> 8 ) & 0xFF;
+                ssl->out_msg[5] = ( ssl->handshake->out_msg_seq      ) & 0xFF;
+                ++( ssl->handshake->out_msg_seq );
+            }
+            else
+            {
+                ssl->out_msg[4] = 0;
+                ssl->out_msg[5] = 0;
+            }
+
+            /* Handshake hashes are computed without fragmentation,
+             * so set frag_offset = 0 and frag_len = hs_len for now */
+            memset( ssl->out_msg + 6, 0x00, 3 );
+            memcpy( ssl->out_msg + 9, ssl->out_msg + 1, 3 );
+        }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+        /* Update running hashes of handshake messages seen */
+        if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
+            ssl->handshake->update_checksum( ssl, ssl->out_msg, ssl->out_msglen );
+    }
+
+    /* Either send now, or just save to be sent (and resent) later */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ! ( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
+            hs_type          == MBEDTLS_SSL_HS_HELLO_REQUEST ) )
+    {
+        if( ( ret = ssl_flight_append( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_flight_append", ret );
+            return( ret );
+        }
+    }
+    else
+#endif
+    {
+        if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_record", ret );
+            return( ret );
+        }
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write handshake message" ) );
+
+    return( 0 );
+}
+
+/*
+ * Record layer functions
+ */
+
+/*
+ * Write current record.
+ *
+ * Uses:
+ *  - ssl->out_msgtype: type of the message (AppData, Handshake, Alert, CCS)
+ *  - ssl->out_msglen: length of the record content (excl headers)
+ *  - ssl->out_msg: record content
+ */
+int mbedtls_ssl_write_record( mbedtls_ssl_context *ssl, uint8_t force_flush )
+{
+    int ret, done = 0;
+    size_t len = ssl->out_msglen;
+    uint8_t flush = force_flush;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write record" ) );
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    if( ssl->transform_out != NULL &&
+        ssl->session_out->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
+    {
+        if( ( ret = ssl_compress_buf( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_compress_buf", ret );
+            return( ret );
+        }
+
+        len = ssl->out_msglen;
+    }
+#endif /*MBEDTLS_ZLIB_SUPPORT */
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_write != NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_write()" ) );
+
+        ret = mbedtls_ssl_hw_record_write( ssl );
+        if( ret != 0 && ret != MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_write", ret );
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+
+        if( ret == 0 )
+            done = 1;
+    }
+#endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
+    if( !done )
+    {
+        unsigned i;
+        size_t protected_record_size;
+
+        ssl->out_hdr[0] = (unsigned char) ssl->out_msgtype;
+        mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
+                           ssl->conf->transport, ssl->out_hdr + 1 );
+
+        memcpy( ssl->out_ctr, ssl->cur_out_ctr, 8 );
+        ssl->out_len[0] = (unsigned char)( len >> 8 );
+        ssl->out_len[1] = (unsigned char)( len      );
+
+        if( ssl->transform_out != NULL )
+        {
+            if( ( ret = ssl_encrypt_buf( ssl ) ) != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_RET( 1, "ssl_encrypt_buf", ret );
+                return( ret );
+            }
+
+            len = ssl->out_msglen;
+            ssl->out_len[0] = (unsigned char)( len >> 8 );
+            ssl->out_len[1] = (unsigned char)( len      );
+        }
+
+        protected_record_size = len + mbedtls_ssl_hdr_len( ssl );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        /* In case of DTLS, double-check that we don't exceed
+         * the remaining space in the datagram. */
+        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        {
+            ret = ssl_get_remaining_space_in_datagram( ssl );
+            if( ret < 0 )
+                return( ret );
+
+            if( protected_record_size > (size_t) ret )
+            {
+                /* Should never happen */
+                return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+            }
+        }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "output record: msgtype = %d, "
+                                    "version = [%d:%d], msglen = %d",
+                                    ssl->out_hdr[0], ssl->out_hdr[1],
+                                    ssl->out_hdr[2], len ) );
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "output record sent to network",
+                               ssl->out_hdr, protected_record_size );
+
+        ssl->out_left += protected_record_size;
+        ssl->out_hdr  += protected_record_size;
+        ssl_update_out_pointers( ssl, ssl->transform_out );
+
+        for( i = 8; i > ssl_ep_len( ssl ); i-- )
+            if( ++ssl->cur_out_ctr[i - 1] != 0 )
+                break;
+
+        /* The loop goes to its end iff the counter is wrapping */
+        if( i == ssl_ep_len( ssl ) )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "outgoing message counter would wrap" ) );
+            return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
+        }
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        flush == SSL_DONT_FORCE_FLUSH )
+    {
+        size_t remaining;
+        ret = ssl_get_remaining_payload_in_datagram( ssl );
+        if( ret < 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_get_remaining_payload_in_datagram",
+                                   ret );
+            return( ret );
+        }
+
+        remaining = (size_t) ret;
+        if( remaining == 0 )
+        {
+            flush = SSL_FORCE_FLUSH;
+        }
+        else
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "Still %u bytes available in current datagram", (unsigned) remaining ) );
+        }
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    if( ( flush == SSL_FORCE_FLUSH ) &&
+        ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write record" ) );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+
+static int ssl_hs_is_proper_fragment( mbedtls_ssl_context *ssl )
+{
+    if( ssl->in_msglen < ssl->in_hslen ||
+        memcmp( ssl->in_msg + 6, "\0\0\0",        3 ) != 0 ||
+        memcmp( ssl->in_msg + 9, ssl->in_msg + 1, 3 ) != 0 )
+    {
+        return( 1 );
+    }
+    return( 0 );
+}
+
+static uint32_t ssl_get_hs_frag_len( mbedtls_ssl_context const *ssl )
+{
+    return( ( ssl->in_msg[9] << 16  ) |
+            ( ssl->in_msg[10] << 8  ) |
+              ssl->in_msg[11] );
+}
+
+static uint32_t ssl_get_hs_frag_off( mbedtls_ssl_context const *ssl )
+{
+    return( ( ssl->in_msg[6] << 16 ) |
+            ( ssl->in_msg[7] << 8  ) |
+              ssl->in_msg[8] );
+}
+
+static int ssl_check_hs_header( mbedtls_ssl_context const *ssl )
+{
+    uint32_t msg_len, frag_off, frag_len;
+
+    msg_len  = ssl_get_hs_total_len( ssl );
+    frag_off = ssl_get_hs_frag_off( ssl );
+    frag_len = ssl_get_hs_frag_len( ssl );
+
+    if( frag_off > msg_len )
+        return( -1 );
+
+    if( frag_len > msg_len - frag_off )
+        return( -1 );
+
+    if( frag_len + 12 > ssl->in_msglen )
+        return( -1 );
+
+    return( 0 );
+}
+
+/*
+ * Mark bits in bitmask (used for DTLS HS reassembly)
+ */
+static void ssl_bitmask_set( unsigned char *mask, size_t offset, size_t len )
+{
+    unsigned int start_bits, end_bits;
+
+    start_bits = 8 - ( offset % 8 );
+    if( start_bits != 8 )
+    {
+        size_t first_byte_idx = offset / 8;
+
+        /* Special case */
+        if( len <= start_bits )
+        {
+            for( ; len != 0; len-- )
+                mask[first_byte_idx] |= 1 << ( start_bits - len );
+
+            /* Avoid potential issues with offset or len becoming invalid */
+            return;
+        }
+
+        offset += start_bits; /* Now offset % 8 == 0 */
+        len -= start_bits;
+
+        for( ; start_bits != 0; start_bits-- )
+            mask[first_byte_idx] |= 1 << ( start_bits - 1 );
+    }
+
+    end_bits = len % 8;
+    if( end_bits != 0 )
+    {
+        size_t last_byte_idx = ( offset + len ) / 8;
+
+        len -= end_bits; /* Now len % 8 == 0 */
+
+        for( ; end_bits != 0; end_bits-- )
+            mask[last_byte_idx] |= 1 << ( 8 - end_bits );
+    }
+
+    memset( mask + offset / 8, 0xFF, len / 8 );
+}
+
+/*
+ * Check that bitmask is full
+ */
+static int ssl_bitmask_check( unsigned char *mask, size_t len )
+{
+    size_t i;
+
+    for( i = 0; i < len / 8; i++ )
+        if( mask[i] != 0xFF )
+            return( -1 );
+
+    for( i = 0; i < len % 8; i++ )
+        if( ( mask[len / 8] & ( 1 << ( 7 - i ) ) ) == 0 )
+            return( -1 );
+
+    return( 0 );
+}
+
+/* msg_len does not include the handshake header */
+static size_t ssl_get_reassembly_buffer_size( size_t msg_len,
+                                              unsigned add_bitmap )
+{
+    size_t alloc_len;
+
+    alloc_len  = 12;                                 /* Handshake header */
+    alloc_len += msg_len;                            /* Content buffer   */
+
+    if( add_bitmap )
+        alloc_len += msg_len / 8 + ( msg_len % 8 != 0 ); /* Bitmap       */
+
+    return( alloc_len );
+}
+
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+static uint32_t ssl_get_hs_total_len( mbedtls_ssl_context const *ssl )
+{
+    return( ( ssl->in_msg[1] << 16 ) |
+            ( ssl->in_msg[2] << 8  ) |
+              ssl->in_msg[3] );
+}
+
+int mbedtls_ssl_prepare_handshake_record( mbedtls_ssl_context *ssl )
+{
+    if( ssl->in_msglen < mbedtls_ssl_hs_hdr_len( ssl ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake message too short: %d",
+                            ssl->in_msglen ) );
+        return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+    }
+
+    ssl->in_hslen = mbedtls_ssl_hs_hdr_len( ssl ) + ssl_get_hs_total_len( ssl );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "handshake message: msglen ="
+                        " %d, type = %d, hslen = %d",
+                        ssl->in_msglen, ssl->in_msg[0], ssl->in_hslen ) );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        int ret;
+        unsigned int recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
+
+        if( ssl_check_hs_header( ssl ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid handshake header" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+
+        if( ssl->handshake != NULL &&
+            ( ( ssl->state   != MBEDTLS_SSL_HANDSHAKE_OVER &&
+                recv_msg_seq != ssl->handshake->in_msg_seq ) ||
+              ( ssl->state  == MBEDTLS_SSL_HANDSHAKE_OVER &&
+                ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO ) ) )
+        {
+            if( recv_msg_seq > ssl->handshake->in_msg_seq )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "received future handshake message of sequence number %u (next %u)",
+                                            recv_msg_seq,
+                                            ssl->handshake->in_msg_seq ) );
+                return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
+            }
+
+            /* Retransmit only on last message from previous flight, to avoid
+             * too many retransmissions.
+             * Besides, No sane server ever retransmits HelloVerifyRequest */
+            if( recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 &&
+                ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "received message from last flight, "
+                                    "message_seq = %d, start_of_flight = %d",
+                                    recv_msg_seq,
+                                    ssl->handshake->in_flight_start_seq ) );
+
+                if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
+                    return( ret );
+                }
+            }
+            else
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "dropping out-of-sequence message: "
+                                    "message_seq = %d, expected = %d",
+                                    recv_msg_seq,
+                                    ssl->handshake->in_msg_seq ) );
+            }
+
+            return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
+        }
+        /* Wait until message completion to increment in_msg_seq */
+
+        /* Message reassembly is handled alongside buffering of future
+         * messages; the commonality is that both handshake fragments and
+         * future messages cannot be forwarded immediately to the
+         * handshake logic layer. */
+        if( ssl_hs_is_proper_fragment( ssl ) == 1 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "found fragmented DTLS handshake message" ) );
+            return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
+        }
+    }
+    else
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+    /* With TLS we don't handle fragmentation (for now) */
+    if( ssl->in_msglen < ssl->in_hslen )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS handshake fragmentation not supported" ) );
+        return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+    }
+
+    return( 0 );
+}
+
+void mbedtls_ssl_update_handshake_status( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+
+    if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER && hs != NULL )
+    {
+        ssl->handshake->update_checksum( ssl, ssl->in_msg, ssl->in_hslen );
+    }
+
+    /* Handshake message is complete, increment counter */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake != NULL )
+    {
+        unsigned offset;
+        mbedtls_ssl_hs_buffer *hs_buf;
+
+        /* Increment handshake sequence number */
+        hs->in_msg_seq++;
+
+        /*
+         * Clear up handshake buffering and reassembly structure.
+         */
+
+        /* Free first entry */
+        ssl_buffering_free_slot( ssl, 0 );
+
+        /* Shift all other entries */
+        for( offset = 0, hs_buf = &hs->buffering.hs[0];
+             offset + 1 < MBEDTLS_SSL_MAX_BUFFERED_HS;
+             offset++, hs_buf++ )
+        {
+            *hs_buf = *(hs_buf + 1);
+        }
+
+        /* Create a fresh last entry */
+        memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
+    }
+#endif
+}
+
+/*
+ * DTLS anti-replay: RFC 6347 4.1.2.6
+ *
+ * in_window is a field of bits numbered from 0 (lsb) to 63 (msb).
+ * Bit n is set iff record number in_window_top - n has been seen.
+ *
+ * Usually, in_window_top is the last record number seen and the lsb of
+ * in_window is set. The only exception is the initial state (record number 0
+ * not seen yet).
+ */
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+static void ssl_dtls_replay_reset( mbedtls_ssl_context *ssl )
+{
+    ssl->in_window_top = 0;
+    ssl->in_window = 0;
+}
+
+static inline uint64_t ssl_load_six_bytes( unsigned char *buf )
+{
+    return( ( (uint64_t) buf[0] << 40 ) |
+            ( (uint64_t) buf[1] << 32 ) |
+            ( (uint64_t) buf[2] << 24 ) |
+            ( (uint64_t) buf[3] << 16 ) |
+            ( (uint64_t) buf[4] <<  8 ) |
+            ( (uint64_t) buf[5]       ) );
+}
+
+/*
+ * Return 0 if sequence number is acceptable, -1 otherwise
+ */
+int mbedtls_ssl_dtls_replay_check( mbedtls_ssl_context *ssl )
+{
+    uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
+    uint64_t bit;
+
+    if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
+        return( 0 );
+
+    if( rec_seqnum > ssl->in_window_top )
+        return( 0 );
+
+    bit = ssl->in_window_top - rec_seqnum;
+
+    if( bit >= 64 )
+        return( -1 );
+
+    if( ( ssl->in_window & ( (uint64_t) 1 << bit ) ) != 0 )
+        return( -1 );
+
+    return( 0 );
+}
+
+/*
+ * Update replay window on new validated record
+ */
+void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl )
+{
+    uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
+
+    if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
+        return;
+
+    if( rec_seqnum > ssl->in_window_top )
+    {
+        /* Update window_top and the contents of the window */
+        uint64_t shift = rec_seqnum - ssl->in_window_top;
+
+        if( shift >= 64 )
+            ssl->in_window = 1;
+        else
+        {
+            ssl->in_window <<= shift;
+            ssl->in_window |= 1;
+        }
+
+        ssl->in_window_top = rec_seqnum;
+    }
+    else
+    {
+        /* Mark that number as seen in the current window */
+        uint64_t bit = ssl->in_window_top - rec_seqnum;
+
+        if( bit < 64 ) /* Always true, but be extra sure */
+            ssl->in_window |= (uint64_t) 1 << bit;
+    }
+}
+#endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
+
+#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
+/* Forward declaration */
+static int ssl_session_reset_int( mbedtls_ssl_context *ssl, int partial );
+
+/*
+ * Without any SSL context, check if a datagram looks like a ClientHello with
+ * a valid cookie, and if it doesn't, generate a HelloVerifyRequest message.
+ * Both input and output include full DTLS headers.
+ *
+ * - if cookie is valid, return 0
+ * - if ClientHello looks superficially valid but cookie is not,
+ *   fill obuf and set olen, then
+ *   return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
+ * - otherwise return a specific error code
+ */
+static int ssl_check_dtls_clihlo_cookie(
+                           mbedtls_ssl_cookie_write_t *f_cookie_write,
+                           mbedtls_ssl_cookie_check_t *f_cookie_check,
+                           void *p_cookie,
+                           const unsigned char *cli_id, size_t cli_id_len,
+                           const unsigned char *in, size_t in_len,
+                           unsigned char *obuf, size_t buf_len, size_t *olen )
+{
+    size_t sid_len, cookie_len;
+    unsigned char *p;
+
+    if( f_cookie_write == NULL || f_cookie_check == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    /*
+     * Structure of ClientHello with record and handshake headers,
+     * and expected values. We don't need to check a lot, more checks will be
+     * done when actually parsing the ClientHello - skipping those checks
+     * avoids code duplication and does not make cookie forging any easier.
+     *
+     *  0-0  ContentType type;                  copied, must be handshake
+     *  1-2  ProtocolVersion version;           copied
+     *  3-4  uint16 epoch;                      copied, must be 0
+     *  5-10 uint48 sequence_number;            copied
+     * 11-12 uint16 length;                     (ignored)
+     *
+     * 13-13 HandshakeType msg_type;            (ignored)
+     * 14-16 uint24 length;                     (ignored)
+     * 17-18 uint16 message_seq;                copied
+     * 19-21 uint24 fragment_offset;            copied, must be 0
+     * 22-24 uint24 fragment_length;            (ignored)
+     *
+     * 25-26 ProtocolVersion client_version;    (ignored)
+     * 27-58 Random random;                     (ignored)
+     * 59-xx SessionID session_id;              1 byte len + sid_len content
+     * 60+   opaque cookie<0..2^8-1>;           1 byte len + content
+     *       ...
+     *
+     * Minimum length is 61 bytes.
+     */
+    if( in_len < 61 ||
+        in[0] != MBEDTLS_SSL_MSG_HANDSHAKE ||
+        in[3] != 0 || in[4] != 0 ||
+        in[19] != 0 || in[20] != 0 || in[21] != 0 )
+    {
+        return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
+    }
+
+    sid_len = in[59];
+    if( sid_len > in_len - 61 )
+        return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
+
+    cookie_len = in[60 + sid_len];
+    if( cookie_len > in_len - 60 )
+        return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
+
+    if( f_cookie_check( p_cookie, in + sid_len + 61, cookie_len,
+                        cli_id, cli_id_len ) == 0 )
+    {
+        /* Valid cookie */
+        return( 0 );
+    }
+
+    /*
+     * If we get here, we've got an invalid cookie, let's prepare HVR.
+     *
+     *  0-0  ContentType type;                  copied
+     *  1-2  ProtocolVersion version;           copied
+     *  3-4  uint16 epoch;                      copied
+     *  5-10 uint48 sequence_number;            copied
+     * 11-12 uint16 length;                     olen - 13
+     *
+     * 13-13 HandshakeType msg_type;            hello_verify_request
+     * 14-16 uint24 length;                     olen - 25
+     * 17-18 uint16 message_seq;                copied
+     * 19-21 uint24 fragment_offset;            copied
+     * 22-24 uint24 fragment_length;            olen - 25
+     *
+     * 25-26 ProtocolVersion server_version;    0xfe 0xff
+     * 27-27 opaque cookie<0..2^8-1>;           cookie_len = olen - 27, cookie
+     *
+     * Minimum length is 28.
+     */
+    if( buf_len < 28 )
+        return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
+
+    /* Copy most fields and adapt others */
+    memcpy( obuf, in, 25 );
+    obuf[13] = MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST;
+    obuf[25] = 0xfe;
+    obuf[26] = 0xff;
+
+    /* Generate and write actual cookie */
+    p = obuf + 28;
+    if( f_cookie_write( p_cookie,
+                        &p, obuf + buf_len, cli_id, cli_id_len ) != 0 )
+    {
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    *olen = p - obuf;
+
+    /* Go back and fill length fields */
+    obuf[27] = (unsigned char)( *olen - 28 );
+
+    obuf[14] = obuf[22] = (unsigned char)( ( *olen - 25 ) >> 16 );
+    obuf[15] = obuf[23] = (unsigned char)( ( *olen - 25 ) >>  8 );
+    obuf[16] = obuf[24] = (unsigned char)( ( *olen - 25 )       );
+
+    obuf[11] = (unsigned char)( ( *olen - 13 ) >>  8 );
+    obuf[12] = (unsigned char)( ( *olen - 13 )       );
+
+    return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
+}
+
+/*
+ * Handle possible client reconnect with the same UDP quadruplet
+ * (RFC 6347 Section 4.2.8).
+ *
+ * Called by ssl_parse_record_header() in case we receive an epoch 0 record
+ * that looks like a ClientHello.
+ *
+ * - if the input looks like a ClientHello without cookies,
+ *   send back HelloVerifyRequest, then
+ *   return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
+ * - if the input looks like a ClientHello with a valid cookie,
+ *   reset the session of the current context, and
+ *   return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
+ * - if anything goes wrong, return a specific error code
+ *
+ * mbedtls_ssl_read_record() will ignore the record if anything else than
+ * MBEDTLS_ERR_SSL_CLIENT_RECONNECT or 0 is returned, although this function
+ * cannot not return 0.
+ */
+static int ssl_handle_possible_reconnect( mbedtls_ssl_context *ssl )
+{
+    int ret;
+    size_t len;
+
+    ret = ssl_check_dtls_clihlo_cookie(
+            ssl->conf->f_cookie_write,
+            ssl->conf->f_cookie_check,
+            ssl->conf->p_cookie,
+            ssl->cli_id, ssl->cli_id_len,
+            ssl->in_buf, ssl->in_left,
+            ssl->out_buf, MBEDTLS_SSL_OUT_CONTENT_LEN, &len );
+
+    MBEDTLS_SSL_DEBUG_RET( 2, "ssl_check_dtls_clihlo_cookie", ret );
+
+    if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
+    {
+        /* Don't check write errors as we can't do anything here.
+         * If the error is permanent we'll catch it later,
+         * if it's not, then hopefully it'll work next time. */
+        (void) ssl->f_send( ssl->p_bio, ssl->out_buf, len );
+
+        return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
+    }
+
+    if( ret == 0 )
+    {
+        /* Got a valid cookie, partially reset context */
+        if( ( ret = ssl_session_reset_int( ssl, 1 ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "reset", ret );
+            return( ret );
+        }
+
+        return( MBEDTLS_ERR_SSL_CLIENT_RECONNECT );
+    }
+
+    return( ret );
+}
+#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
+
+/*
+ * ContentType type;
+ * ProtocolVersion version;
+ * uint16 epoch;            // DTLS only
+ * uint48 sequence_number;  // DTLS only
+ * uint16 length;
+ *
+ * Return 0 if header looks sane (and, for DTLS, the record is expected)
+ * MBEDTLS_ERR_SSL_INVALID_RECORD if the header looks bad,
+ * MBEDTLS_ERR_SSL_UNEXPECTED_RECORD (DTLS only) if sane but unexpected.
+ *
+ * With DTLS, mbedtls_ssl_read_record() will:
+ * 1. proceed with the record if this function returns 0
+ * 2. drop only the current record if this function returns UNEXPECTED_RECORD
+ * 3. return CLIENT_RECONNECT if this function return that value
+ * 4. drop the whole datagram if this function returns anything else.
+ * Point 2 is needed when the peer is resending, and we have already received
+ * the first record from a datagram but are still waiting for the others.
+ */
+static int ssl_parse_record_header( mbedtls_ssl_context *ssl )
+{
+    int major_ver, minor_ver;
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "input record header", ssl->in_hdr, mbedtls_ssl_hdr_len( ssl ) );
+
+    ssl->in_msgtype =  ssl->in_hdr[0];
+    ssl->in_msglen = ( ssl->in_len[0] << 8 ) | ssl->in_len[1];
+    mbedtls_ssl_read_version( &major_ver, &minor_ver, ssl->conf->transport, ssl->in_hdr + 1 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "input record: msgtype = %d, "
+                        "version = [%d:%d], msglen = %d",
+                        ssl->in_msgtype,
+                        major_ver, minor_ver, ssl->in_msglen ) );
+
+    /* Check record type */
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE &&
+        ssl->in_msgtype != MBEDTLS_SSL_MSG_ALERT &&
+        ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
+        ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type" ) );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        /* Silently ignore invalid DTLS records as recommended by RFC 6347
+         * Section 4.1.2.7 */
+        if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+            mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+
+        return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+    }
+
+    /* Check version */
+    if( major_ver != ssl->major_ver )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "major version mismatch" ) );
+        return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+    }
+
+    if( minor_ver > ssl->conf->max_minor_ver )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "minor version mismatch" ) );
+        return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+    }
+
+    /* Check length against the size of our buffer */
+    if( ssl->in_msglen > MBEDTLS_SSL_IN_BUFFER_LEN
+                         - (size_t)( ssl->in_msg - ssl->in_buf ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+        return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+    }
+
+    /*
+     * DTLS-related tests.
+     * Check epoch before checking length constraint because
+     * the latter varies with the epoch. E.g., if a ChangeCipherSpec
+     * message gets duplicated before the corresponding Finished message,
+     * the second ChangeCipherSpec should be discarded because it belongs
+     * to an old epoch, but not because its length is shorter than
+     * the minimum record length for packets using the new record transform.
+     * Note that these two kinds of failures are handled differently,
+     * as an unexpected record is silently skipped but an invalid
+     * record leads to the entire datagram being dropped.
+     */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        unsigned int rec_epoch = ( ssl->in_ctr[0] << 8 ) | ssl->in_ctr[1];
+
+        /* Check epoch (and sequence number) with DTLS */
+        if( rec_epoch != ssl->in_epoch )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "record from another epoch: "
+                                        "expected %d, received %d",
+                                        ssl->in_epoch, rec_epoch ) );
+
+#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
+            /*
+             * Check for an epoch 0 ClientHello. We can't use in_msg here to
+             * access the first byte of record content (handshake type), as we
+             * have an active transform (possibly iv_len != 0), so use the
+             * fact that the record header len is 13 instead.
+             */
+            if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
+                ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER &&
+                rec_epoch == 0 &&
+                ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
+                ssl->in_left > 13 &&
+                ssl->in_buf[13] == MBEDTLS_SSL_HS_CLIENT_HELLO )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "possible client reconnect "
+                                            "from the same port" ) );
+                return( ssl_handle_possible_reconnect( ssl ) );
+            }
+            else
+#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
+            {
+                /* Consider buffering the record. */
+                if( rec_epoch == (unsigned int) ssl->in_epoch + 1 )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Consider record for buffering" ) );
+                    return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
+                }
+
+                return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
+            }
+        }
+
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+        /* Replay detection only works for the current epoch */
+        if( rec_epoch == ssl->in_epoch &&
+            mbedtls_ssl_dtls_replay_check( ssl ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "replayed record" ) );
+            return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
+        }
+#endif
+
+        /* Drop unexpected ApplicationData records,
+         * except at the beginning of renegotiations */
+        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
+            ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+            && ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
+                   ssl->state == MBEDTLS_SSL_SERVER_HELLO )
+#endif
+            )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
+            return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
+        }
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+
+    /* Check length against bounds of the current transform and version */
+    if( ssl->transform_in == NULL )
+    {
+        if( ssl->in_msglen < 1 ||
+            ssl->in_msglen > MBEDTLS_SSL_IN_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+    }
+    else
+    {
+        if( ssl->in_msglen < ssl->transform_in->minlen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
+            ssl->in_msglen > ssl->transform_in->minlen + MBEDTLS_SSL_IN_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        /*
+         * TLS encrypted messages can have up to 256 bytes of padding
+         */
+        if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 &&
+            ssl->in_msglen > ssl->transform_in->minlen +
+                             MBEDTLS_SSL_IN_CONTENT_LEN + 256 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+#endif
+    }
+
+    return( 0 );
+}
+
+/*
+ * If applicable, decrypt (and decompress) record content
+ */
+static int ssl_prepare_record_content( mbedtls_ssl_context *ssl )
+{
+    int ret, done = 0;
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "input record from network",
+                   ssl->in_hdr, mbedtls_ssl_hdr_len( ssl ) + ssl->in_msglen );
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_read != NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_read()" ) );
+
+        ret = mbedtls_ssl_hw_record_read( ssl );
+        if( ret != 0 && ret != MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_read", ret );
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+
+        if( ret == 0 )
+            done = 1;
+    }
+#endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
+    if( !done && ssl->transform_in != NULL )
+    {
+        if( ( ret = ssl_decrypt_buf( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decrypt_buf", ret );
+            return( ret );
+        }
+
+        MBEDTLS_SSL_DEBUG_BUF( 4, "input payload after decrypt",
+                       ssl->in_msg, ssl->in_msglen );
+
+        if( ssl->in_msglen > MBEDTLS_SSL_IN_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+    }
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    if( ssl->transform_in != NULL &&
+        ssl->session_in->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
+    {
+        if( ( ret = ssl_decompress_buf( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decompress_buf", ret );
+            return( ret );
+        }
+    }
+#endif /* MBEDTLS_ZLIB_SUPPORT */
+
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        mbedtls_ssl_dtls_replay_update( ssl );
+    }
+#endif
+
+    return( 0 );
+}
+
+static void ssl_handshake_wrapup_free_hs_transform( mbedtls_ssl_context *ssl );
+
+/*
+ * Read a record.
+ *
+ * Silently ignore non-fatal alert (and for DTLS, invalid records as well,
+ * RFC 6347 4.1.2.7) and continue reading until a valid record is found.
+ *
+ */
+
+/* Helper functions for mbedtls_ssl_read_record(). */
+static int ssl_consume_current_message( mbedtls_ssl_context *ssl );
+static int ssl_get_next_record( mbedtls_ssl_context *ssl );
+static int ssl_record_is_in_progress( mbedtls_ssl_context *ssl );
+
+int mbedtls_ssl_read_record( mbedtls_ssl_context *ssl,
+                             unsigned update_hs_digest )
+{
+    int ret;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read record" ) );
+
+    if( ssl->keep_current_message == 0 )
+    {
+        do {
+
+            ret = ssl_consume_current_message( ssl );
+            if( ret != 0 )
+                return( ret );
+
+            if( ssl_record_is_in_progress( ssl ) == 0 )
+            {
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+                int have_buffered = 0;
+
+                /* We only check for buffered messages if the
+                 * current datagram is fully consumed. */
+                if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+                    ssl_next_record_is_in_datagram( ssl ) == 0 )
+                {
+                    if( ssl_load_buffered_message( ssl ) == 0 )
+                        have_buffered = 1;
+                }
+
+                if( have_buffered == 0 )
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+                {
+                    ret = ssl_get_next_record( ssl );
+                    if( ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING )
+                        continue;
+
+                    if( ret != 0 )
+                    {
+                        MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_get_next_record" ), ret );
+                        return( ret );
+                    }
+                }
+            }
+
+            ret = mbedtls_ssl_handle_message_type( ssl );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+            if( ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
+            {
+                /* Buffer future message */
+                ret = ssl_buffer_message( ssl );
+                if( ret != 0 )
+                    return( ret );
+
+                ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
+            }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+        } while( MBEDTLS_ERR_SSL_NON_FATAL           == ret  ||
+                 MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret );
+
+        if( 0 != ret )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ssl_handle_message_type" ), ret );
+            return( ret );
+        }
+
+        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
+            update_hs_digest == 1 )
+        {
+            mbedtls_ssl_update_handshake_status( ssl );
+        }
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "reuse previously read message" ) );
+        ssl->keep_current_message = 0;
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read record" ) );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+static int ssl_next_record_is_in_datagram( mbedtls_ssl_context *ssl )
+{
+    if( ssl->in_left > ssl->next_record_offset )
+        return( 1 );
+
+    return( 0 );
+}
+
+static int ssl_load_buffered_message( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+    mbedtls_ssl_hs_buffer * hs_buf;
+    int ret = 0;
+
+    if( hs == NULL )
+        return( -1 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_load_buffered_messsage" ) );
+
+    if( ssl->state == MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC ||
+        ssl->state == MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
+    {
+        /* Check if we have seen a ChangeCipherSpec before.
+         * If yes, synthesize a CCS record. */
+        if( !hs->buffering.seen_ccs )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "CCS not seen in the current flight" ) );
+            ret = -1;
+            goto exit;
+        }
+
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Injecting buffered CCS message" ) );
+        ssl->in_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
+        ssl->in_msglen = 1;
+        ssl->in_msg[0] = 1;
+
+        /* As long as they are equal, the exact value doesn't matter. */
+        ssl->in_left            = 0;
+        ssl->next_record_offset = 0;
+
+        hs->buffering.seen_ccs = 0;
+        goto exit;
+    }
+
+#if defined(MBEDTLS_DEBUG_C)
+    /* Debug only */
+    {
+        unsigned offset;
+        for( offset = 1; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++ )
+        {
+            hs_buf = &hs->buffering.hs[offset];
+            if( hs_buf->is_valid == 1 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "Future message with sequence number %u %s buffered.",
+                            hs->in_msg_seq + offset,
+                            hs_buf->is_complete ? "fully" : "partially" ) );
+            }
+        }
+    }
+#endif /* MBEDTLS_DEBUG_C */
+
+    /* Check if we have buffered and/or fully reassembled the
+     * next handshake message. */
+    hs_buf = &hs->buffering.hs[0];
+    if( ( hs_buf->is_valid == 1 ) && ( hs_buf->is_complete == 1 ) )
+    {
+        /* Synthesize a record containing the buffered HS message. */
+        size_t msg_len = ( hs_buf->data[1] << 16 ) |
+                         ( hs_buf->data[2] << 8  ) |
+                           hs_buf->data[3];
+
+        /* Double-check that we haven't accidentally buffered
+         * a message that doesn't fit into the input buffer. */
+        if( msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Next handshake message has been buffered - load" ) );
+        MBEDTLS_SSL_DEBUG_BUF( 3, "Buffered handshake message (incl. header)",
+                               hs_buf->data, msg_len + 12 );
+
+        ssl->in_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
+        ssl->in_hslen   = msg_len + 12;
+        ssl->in_msglen  = msg_len + 12;
+        memcpy( ssl->in_msg, hs_buf->data, ssl->in_hslen );
+
+        ret = 0;
+        goto exit;
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Next handshake message %u not or only partially bufffered",
+                                    hs->in_msg_seq ) );
+    }
+
+    ret = -1;
+
+exit:
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_load_buffered_message" ) );
+    return( ret );
+}
+
+static int ssl_buffer_make_space( mbedtls_ssl_context *ssl,
+                                  size_t desired )
+{
+    int offset;
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Attempt to free buffered messages to have %u bytes available",
+                                (unsigned) desired ) );
+
+    /* Get rid of future records epoch first, if such exist. */
+    ssl_free_buffered_record( ssl );
+
+    /* Check if we have enough space available now. */
+    if( desired <= ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
+                     hs->buffering.total_bytes_buffered ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Enough space available after freeing future epoch record" ) );
+        return( 0 );
+    }
+
+    /* We don't have enough space to buffer the next expected handshake
+     * message. Remove buffers used for future messages to gain space,
+     * starting with the most distant one. */
+    for( offset = MBEDTLS_SSL_MAX_BUFFERED_HS - 1;
+         offset >= 0; offset-- )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Free buffering slot %d to make space for reassembly of next handshake message",
+                                    offset ) );
+
+        ssl_buffering_free_slot( ssl, (uint8_t) offset );
+
+        /* Check if we have enough space available now. */
+        if( desired <= ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
+                         hs->buffering.total_bytes_buffered ) )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "Enough space available after freeing buffered HS messages" ) );
+            return( 0 );
+        }
+    }
+
+    return( -1 );
+}
+
+static int ssl_buffer_message( mbedtls_ssl_context *ssl )
+{
+    int ret = 0;
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+
+    if( hs == NULL )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_buffer_message" ) );
+
+    switch( ssl->in_msgtype )
+    {
+        case MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC:
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "Remember CCS message" ) );
+
+            hs->buffering.seen_ccs = 1;
+            break;
+
+        case MBEDTLS_SSL_MSG_HANDSHAKE:
+        {
+            unsigned recv_msg_seq_offset;
+            unsigned recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
+            mbedtls_ssl_hs_buffer *hs_buf;
+            size_t msg_len = ssl->in_hslen - 12;
+
+            /* We should never receive an old handshake
+             * message - double-check nonetheless. */
+            if( recv_msg_seq < ssl->handshake->in_msg_seq )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+                return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+            }
+
+            recv_msg_seq_offset = recv_msg_seq - ssl->handshake->in_msg_seq;
+            if( recv_msg_seq_offset >= MBEDTLS_SSL_MAX_BUFFERED_HS )
+            {
+                /* Silently ignore -- message too far in the future */
+                MBEDTLS_SSL_DEBUG_MSG( 2,
+                 ( "Ignore future HS message with sequence number %u, "
+                   "buffering window %u - %u",
+                   recv_msg_seq, ssl->handshake->in_msg_seq,
+                   ssl->handshake->in_msg_seq + MBEDTLS_SSL_MAX_BUFFERED_HS - 1 ) );
+
+                goto exit;
+            }
+
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering HS message with sequence number %u, offset %u ",
+                                        recv_msg_seq, recv_msg_seq_offset ) );
+
+            hs_buf = &hs->buffering.hs[ recv_msg_seq_offset ];
+
+            /* Check if the buffering for this seq nr has already commenced. */
+            if( !hs_buf->is_valid )
+            {
+                size_t reassembly_buf_sz;
+
+                hs_buf->is_fragmented =
+                    ( ssl_hs_is_proper_fragment( ssl ) == 1 );
+
+                /* We copy the message back into the input buffer
+                 * after reassembly, so check that it's not too large.
+                 * This is an implementation-specific limitation
+                 * and not one from the standard, hence it is not
+                 * checked in ssl_check_hs_header(). */
+                if( msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN )
+                {
+                    /* Ignore message */
+                    goto exit;
+                }
+
+                /* Check if we have enough space to buffer the message. */
+                if( hs->buffering.total_bytes_buffered >
+                    MBEDTLS_SSL_DTLS_MAX_BUFFERING )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+                    return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+                }
+
+                reassembly_buf_sz = ssl_get_reassembly_buffer_size( msg_len,
+                                                       hs_buf->is_fragmented );
+
+                if( reassembly_buf_sz > ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
+                                          hs->buffering.total_bytes_buffered ) )
+                {
+                    if( recv_msg_seq_offset > 0 )
+                    {
+                        /* If we can't buffer a future message because
+                         * of space limitations -- ignore. */
+                        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future message of size %u would exceed the compile-time limit %u (already %u bytes buffered) -- ignore\n",
+                             (unsigned) msg_len, MBEDTLS_SSL_DTLS_MAX_BUFFERING,
+                             (unsigned) hs->buffering.total_bytes_buffered ) );
+                        goto exit;
+                    }
+                    else
+                    {
+                        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future message of size %u would exceed the compile-time limit %u (already %u bytes buffered) -- attempt to make space by freeing buffered future messages\n",
+                             (unsigned) msg_len, MBEDTLS_SSL_DTLS_MAX_BUFFERING,
+                             (unsigned) hs->buffering.total_bytes_buffered ) );
+                    }
+
+                    if( ssl_buffer_make_space( ssl, reassembly_buf_sz ) != 0 )
+                    {
+                        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reassembly of next message of size %u (%u with bitmap) would exceed the compile-time limit %u (already %u bytes buffered) -- fail\n",
+                             (unsigned) msg_len,
+                             (unsigned) reassembly_buf_sz,
+                             MBEDTLS_SSL_DTLS_MAX_BUFFERING,
+                             (unsigned) hs->buffering.total_bytes_buffered ) );
+                        ret = MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
+                        goto exit;
+                    }
+                }
+
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialize reassembly, total length = %d",
+                                            msg_len ) );
+
+                hs_buf->data = mbedtls_calloc( 1, reassembly_buf_sz );
+                if( hs_buf->data == NULL )
+                {
+                    ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+                    goto exit;
+                }
+                hs_buf->data_len = reassembly_buf_sz;
+
+                /* Prepare final header: copy msg_type, length and message_seq,
+                 * then add standardised fragment_offset and fragment_length */
+                memcpy( hs_buf->data, ssl->in_msg, 6 );
+                memset( hs_buf->data + 6, 0, 3 );
+                memcpy( hs_buf->data + 9, hs_buf->data + 1, 3 );
+
+                hs_buf->is_valid = 1;
+
+                hs->buffering.total_bytes_buffered += reassembly_buf_sz;
+            }
+            else
+            {
+                /* Make sure msg_type and length are consistent */
+                if( memcmp( hs_buf->data, ssl->in_msg, 4 ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "Fragment header mismatch - ignore" ) );
+                    /* Ignore */
+                    goto exit;
+                }
+            }
+
+            if( !hs_buf->is_complete )
+            {
+                size_t frag_len, frag_off;
+                unsigned char * const msg = hs_buf->data + 12;
+
+                /*
+                 * Check and copy current fragment
+                 */
+
+                /* Validation of header fields already done in
+                 * mbedtls_ssl_prepare_handshake_record(). */
+                frag_off = ssl_get_hs_frag_off( ssl );
+                frag_len = ssl_get_hs_frag_len( ssl );
+
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "adding fragment, offset = %d, length = %d",
+                                            frag_off, frag_len ) );
+                memcpy( msg + frag_off, ssl->in_msg + 12, frag_len );
+
+                if( hs_buf->is_fragmented )
+                {
+                    unsigned char * const bitmask = msg + msg_len;
+                    ssl_bitmask_set( bitmask, frag_off, frag_len );
+                    hs_buf->is_complete = ( ssl_bitmask_check( bitmask,
+                                                               msg_len ) == 0 );
+                }
+                else
+                {
+                    hs_buf->is_complete = 1;
+                }
+
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "message %scomplete",
+                                   hs_buf->is_complete ? "" : "not yet " ) );
+            }
+
+            break;
+        }
+
+        default:
+            /* We don't buffer other types of messages. */
+            break;
+    }
+
+exit:
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_buffer_message" ) );
+    return( ret );
+}
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+static int ssl_consume_current_message( mbedtls_ssl_context *ssl )
+{
+    /*
+     * Consume last content-layer message and potentially
+     * update in_msglen which keeps track of the contents'
+     * consumption state.
+     *
+     * (1) Handshake messages:
+     *     Remove last handshake message, move content
+     *     and adapt in_msglen.
+     *
+     * (2) Alert messages:
+     *     Consume whole record content, in_msglen = 0.
+     *
+     * (3) Change cipher spec:
+     *     Consume whole record content, in_msglen = 0.
+     *
+     * (4) Application data:
+     *     Don't do anything - the record layer provides
+     *     the application data as a stream transport
+     *     and consumes through mbedtls_ssl_read only.
+     *
+     */
+
+    /* Case (1): Handshake messages */
+    if( ssl->in_hslen != 0 )
+    {
+        /* Hard assertion to be sure that no application data
+         * is in flight, as corrupting ssl->in_msglen during
+         * ssl->in_offt != NULL is fatal. */
+        if( ssl->in_offt != NULL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        /*
+         * Get next Handshake message in the current record
+         */
+
+        /* Notes:
+         * (1) in_hslen is not necessarily the size of the
+         *     current handshake content: If DTLS handshake
+         *     fragmentation is used, that's the fragment
+         *     size instead. Using the total handshake message
+         *     size here is faulty and should be changed at
+         *     some point.
+         * (2) While it doesn't seem to cause problems, one
+         *     has to be very careful not to assume that in_hslen
+         *     is always <= in_msglen in a sensible communication.
+         *     Again, it's wrong for DTLS handshake fragmentation.
+         *     The following check is therefore mandatory, and
+         *     should not be treated as a silently corrected assertion.
+         *     Additionally, ssl->in_hslen might be arbitrarily out of
+         *     bounds after handling a DTLS message with an unexpected
+         *     sequence number, see mbedtls_ssl_prepare_handshake_record.
+         */
+        if( ssl->in_hslen < ssl->in_msglen )
+        {
+            ssl->in_msglen -= ssl->in_hslen;
+            memmove( ssl->in_msg, ssl->in_msg + ssl->in_hslen,
+                     ssl->in_msglen );
+
+            MBEDTLS_SSL_DEBUG_BUF( 4, "remaining content in record",
+                                   ssl->in_msg, ssl->in_msglen );
+        }
+        else
+        {
+            ssl->in_msglen = 0;
+        }
+
+        ssl->in_hslen   = 0;
+    }
+    /* Case (4): Application data */
+    else if( ssl->in_offt != NULL )
+    {
+        return( 0 );
+    }
+    /* Everything else (CCS & Alerts) */
+    else
+    {
+        ssl->in_msglen = 0;
+    }
+
+    return( 0 );
+}
+
+static int ssl_record_is_in_progress( mbedtls_ssl_context *ssl )
+{
+    if( ssl->in_msglen > 0 )
+        return( 1 );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+
+static void ssl_free_buffered_record( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+    if( hs == NULL )
+        return;
+
+    if( hs->buffering.future_record.data != NULL )
+    {
+        hs->buffering.total_bytes_buffered -=
+            hs->buffering.future_record.len;
+
+        mbedtls_free( hs->buffering.future_record.data );
+        hs->buffering.future_record.data = NULL;
+    }
+}
+
+static int ssl_load_buffered_record( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+    unsigned char * rec;
+    size_t rec_len;
+    unsigned rec_epoch;
+
+    if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        return( 0 );
+
+    if( hs == NULL )
+        return( 0 );
+
+    rec       = hs->buffering.future_record.data;
+    rec_len   = hs->buffering.future_record.len;
+    rec_epoch = hs->buffering.future_record.epoch;
+
+    if( rec == NULL )
+        return( 0 );
+
+    /* Only consider loading future records if the
+     * input buffer is empty. */
+    if( ssl_next_record_is_in_datagram( ssl ) == 1 )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_load_buffered_record" ) );
+
+    if( rec_epoch != ssl->in_epoch )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffered record not from current epoch." ) );
+        goto exit;
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Found buffered record from current epoch - load" ) );
+
+    /* Double-check that the record is not too large */
+    if( rec_len > MBEDTLS_SSL_IN_BUFFER_LEN -
+        (size_t)( ssl->in_hdr - ssl->in_buf ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    memcpy( ssl->in_hdr, rec, rec_len );
+    ssl->in_left = rec_len;
+    ssl->next_record_offset = 0;
+
+    ssl_free_buffered_record( ssl );
+
+exit:
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_load_buffered_record" ) );
+    return( 0 );
+}
+
+static int ssl_buffer_future_record( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+    size_t const rec_hdr_len = 13;
+    size_t const total_buf_sz = rec_hdr_len + ssl->in_msglen;
+
+    /* Don't buffer future records outside handshakes. */
+    if( hs == NULL )
+        return( 0 );
+
+    /* Only buffer handshake records (we are only interested
+     * in Finished messages). */
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+        return( 0 );
+
+    /* Don't buffer more than one future epoch record. */
+    if( hs->buffering.future_record.data != NULL )
+        return( 0 );
+
+    /* Don't buffer record if there's not enough buffering space remaining. */
+    if( total_buf_sz > ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
+                         hs->buffering.total_bytes_buffered ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future epoch record of size %u would exceed the compile-time limit %u (already %u bytes buffered) -- ignore\n",
+                        (unsigned) total_buf_sz, MBEDTLS_SSL_DTLS_MAX_BUFFERING,
+                        (unsigned) hs->buffering.total_bytes_buffered ) );
+        return( 0 );
+    }
+
+    /* Buffer record */
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffer record from epoch %u",
+                                ssl->in_epoch + 1 ) );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "Buffered record", ssl->in_hdr,
+                           rec_hdr_len + ssl->in_msglen );
+
+    /* ssl_parse_record_header() only considers records
+     * of the next epoch as candidates for buffering. */
+    hs->buffering.future_record.epoch = ssl->in_epoch + 1;
+    hs->buffering.future_record.len   = total_buf_sz;
+
+    hs->buffering.future_record.data =
+        mbedtls_calloc( 1, hs->buffering.future_record.len );
+    if( hs->buffering.future_record.data == NULL )
+    {
+        /* If we run out of RAM trying to buffer a
+         * record from the next epoch, just ignore. */
+        return( 0 );
+    }
+
+    memcpy( hs->buffering.future_record.data, ssl->in_hdr, total_buf_sz );
+
+    hs->buffering.total_bytes_buffered += total_buf_sz;
+    return( 0 );
+}
+
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+static int ssl_get_next_record( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    /* We might have buffered a future record; if so,
+     * and if the epoch matches now, load it.
+     * On success, this call will set ssl->in_left to
+     * the length of the buffered record, so that
+     * the calls to ssl_fetch_input() below will
+     * essentially be no-ops. */
+    ret = ssl_load_buffered_record( ssl );
+    if( ret != 0 )
+        return( ret );
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    if( ( ret = mbedtls_ssl_fetch_input( ssl, mbedtls_ssl_hdr_len( ssl ) ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
+        return( ret );
+    }
+
+    if( ( ret = ssl_parse_record_header( ssl ) ) != 0 )
+    {
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+            ret != MBEDTLS_ERR_SSL_CLIENT_RECONNECT )
+        {
+            if( ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
+            {
+                ret = ssl_buffer_future_record( ssl );
+                if( ret != 0 )
+                    return( ret );
+
+                /* Fall through to handling of unexpected records */
+                ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
+            }
+
+            if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_RECORD )
+            {
+                /* Skip unexpected record (but not whole datagram) */
+                ssl->next_record_offset = ssl->in_msglen
+                                        + mbedtls_ssl_hdr_len( ssl );
+
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding unexpected record "
+                                            "(header)" ) );
+            }
+            else
+            {
+                /* Skip invalid record and the rest of the datagram */
+                ssl->next_record_offset = 0;
+                ssl->in_left = 0;
+
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record "
+                                            "(header)" ) );
+            }
+
+            /* Get next record */
+            return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
+        }
+#endif
+        return( ret );
+    }
+
+    /*
+     * Read and optionally decrypt the message contents
+     */
+    if( ( ret = mbedtls_ssl_fetch_input( ssl,
+                                 mbedtls_ssl_hdr_len( ssl ) + ssl->in_msglen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
+        return( ret );
+    }
+
+    /* Done reading this record, get ready for the next one */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        ssl->next_record_offset = ssl->in_msglen + mbedtls_ssl_hdr_len( ssl );
+        if( ssl->next_record_offset < ssl->in_left )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "more than one record within datagram" ) );
+        }
+    }
+    else
+#endif
+        ssl->in_left = 0;
+
+    if( ( ret = ssl_prepare_record_content( ssl ) ) != 0 )
+    {
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        {
+            /* Silently discard invalid records */
+            if( ret == MBEDTLS_ERR_SSL_INVALID_RECORD ||
+                ret == MBEDTLS_ERR_SSL_INVALID_MAC )
+            {
+                /* Except when waiting for Finished as a bad mac here
+                 * probably means something went wrong in the handshake
+                 * (eg wrong psk used, mitm downgrade attempt, etc.) */
+                if( ssl->state == MBEDTLS_SSL_CLIENT_FINISHED ||
+                    ssl->state == MBEDTLS_SSL_SERVER_FINISHED )
+                {
+#if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
+                    if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
+                    {
+                        mbedtls_ssl_send_alert_message( ssl,
+                                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
+                    }
+#endif
+                    return( ret );
+                }
+
+#if defined(MBEDTLS_SSL_DTLS_BADMAC_LIMIT)
+                if( ssl->conf->badmac_limit != 0 &&
+                    ++ssl->badmac_seen >= ssl->conf->badmac_limit )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "too many records with bad MAC" ) );
+                    return( MBEDTLS_ERR_SSL_INVALID_MAC );
+                }
+#endif
+
+                /* As above, invalid records cause
+                 * dismissal of the whole datagram. */
+
+                ssl->next_record_offset = 0;
+                ssl->in_left = 0;
+
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record (mac)" ) );
+                return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
+            }
+
+            return( ret );
+        }
+        else
+#endif
+        {
+            /* Error out (and send alert) on invalid records */
+#if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
+            if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
+            {
+                mbedtls_ssl_send_alert_message( ssl,
+                        MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                        MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
+            }
+#endif
+            return( ret );
+        }
+    }
+
+    return( 0 );
+}
+
+int mbedtls_ssl_handle_message_type( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    /*
+     * Handle particular types of records
+     */
+    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        if( ( ret = mbedtls_ssl_prepare_handshake_record( ssl ) ) != 0 )
+        {
+            return( ret );
+        }
+    }
+
+    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
+    {
+        if( ssl->in_msglen != 1 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, len: %d",
+                           ssl->in_msglen ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+
+        if( ssl->in_msg[0] != 1 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, content: %02x",
+                                        ssl->in_msg[0] ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+            ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC    &&
+            ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
+        {
+            if( ssl->handshake == NULL )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping ChangeCipherSpec outside handshake" ) );
+                return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
+            }
+
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "received out-of-order ChangeCipherSpec - remember" ) );
+            return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
+        }
+#endif
+    }
+
+    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
+    {
+        if( ssl->in_msglen != 2 )
+        {
+            /* Note: Standard allows for more than one 2 byte alert
+               to be packed in a single message, but Mbed TLS doesn't
+               currently support this. */
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid alert message, len: %d",
+                           ssl->in_msglen ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "got an alert message, type: [%d:%d]",
+                       ssl->in_msg[0], ssl->in_msg[1] ) );
+
+        /*
+         * Ignore non-fatal alerts, except close_notify and no_renegotiation
+         */
+        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "is a fatal alert message (msg %d)",
+                           ssl->in_msg[1] ) );
+            return( MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
+        }
+
+        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
+            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a close notify message" ) );
+            return( MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY );
+        }
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED)
+        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
+            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no renegotiation alert" ) );
+            /* Will be handled when trying to parse ServerHello */
+            return( 0 );
+        }
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) && defined(MBEDTLS_SSL_SRV_C)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
+            ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
+            ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
+            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_CERT )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no_cert" ) );
+            /* Will be handled in mbedtls_ssl_parse_certificate() */
+            return( 0 );
+        }
+#endif /* MBEDTLS_SSL_PROTO_SSL3 && MBEDTLS_SSL_SRV_C */
+
+        /* Silently ignore: fetch new message */
+        return MBEDTLS_ERR_SSL_NON_FATAL;
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake != NULL &&
+        ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER  )
+    {
+        ssl_handshake_wrapup_free_hs_transform( ssl );
+    }
+#endif
+
+    return( 0 );
+}
+
+int mbedtls_ssl_send_fatal_handshake_failure( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    if( ( ret = mbedtls_ssl_send_alert_message( ssl,
+                    MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                    MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE ) ) != 0 )
+    {
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_ssl_send_alert_message( mbedtls_ssl_context *ssl,
+                            unsigned char level,
+                            unsigned char message )
+{
+    int ret;
+
+    if( ssl == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> send alert message" ) );
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "send alert level=%u message=%u", level, message ));
+
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT;
+    ssl->out_msglen = 2;
+    ssl->out_msg[0] = level;
+    ssl->out_msg[1] = message;
+
+    if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
+        return( ret );
+    }
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= send alert message" ) );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+static void ssl_clear_peer_cert( mbedtls_ssl_session *session )
+{
+#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    if( session->peer_cert != NULL )
+    {
+        mbedtls_x509_crt_free( session->peer_cert );
+        mbedtls_free( session->peer_cert );
+        session->peer_cert = NULL;
+    }
+#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+    if( session->peer_cert_digest != NULL )
+    {
+        /* Zeroization is not necessary. */
+        mbedtls_free( session->peer_cert_digest );
+        session->peer_cert_digest      = NULL;
+        session->peer_cert_digest_type = MBEDTLS_MD_NONE;
+        session->peer_cert_digest_len  = 0;
+    }
+#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+}
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+/*
+ * Handshake functions
+ */
+#if !defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+/* No certificate support -> dummy functions */
+int mbedtls_ssl_write_certificate( mbedtls_ssl_context *ssl )
+{
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
+
+    if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+    return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+}
+
+int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
+{
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
+
+    if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+    return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+}
+
+#else /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
+/* Some certificate support -> implement write and parse */
+
+int mbedtls_ssl_write_certificate( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+    size_t i, n;
+    const mbedtls_x509_crt *crt;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
+
+    if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+#if defined(MBEDTLS_SSL_CLI_C)
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+    {
+        if( ssl->client_auth == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
+            ssl->state++;
+            return( 0 );
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+        /*
+         * If using SSLv3 and got no cert, send an Alert message
+         * (otherwise an empty Certificate message will be sent).
+         */
+        if( mbedtls_ssl_own_cert( ssl )  == NULL &&
+            ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+        {
+            ssl->out_msglen  = 2;
+            ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT;
+            ssl->out_msg[0]  = MBEDTLS_SSL_ALERT_LEVEL_WARNING;
+            ssl->out_msg[1]  = MBEDTLS_SSL_ALERT_MSG_NO_CERT;
+
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "got no certificate to send" ) );
+            goto write_msg;
+        }
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+    }
+#endif /* MBEDTLS_SSL_CLI_C */
+#if defined(MBEDTLS_SSL_SRV_C)
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        if( mbedtls_ssl_own_cert( ssl ) == NULL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no certificate to send" ) );
+            return( MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED );
+        }
+    }
+#endif
+
+    MBEDTLS_SSL_DEBUG_CRT( 3, "own certificate", mbedtls_ssl_own_cert( ssl ) );
+
+    /*
+     *     0  .  0    handshake type
+     *     1  .  3    handshake length
+     *     4  .  6    length of all certs
+     *     7  .  9    length of cert. 1
+     *    10  . n-1   peer certificate
+     *     n  . n+2   length of cert. 2
+     *    n+3 . ...   upper level cert, etc.
+     */
+    i = 7;
+    crt = mbedtls_ssl_own_cert( ssl );
+
+    while( crt != NULL )
+    {
+        n = crt->raw.len;
+        if( n > MBEDTLS_SSL_OUT_CONTENT_LEN - 3 - i )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "certificate too large, %d > %d",
+                           i + 3 + n, MBEDTLS_SSL_OUT_CONTENT_LEN ) );
+            return( MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE );
+        }
+
+        ssl->out_msg[i    ] = (unsigned char)( n >> 16 );
+        ssl->out_msg[i + 1] = (unsigned char)( n >>  8 );
+        ssl->out_msg[i + 2] = (unsigned char)( n       );
+
+        i += 3; memcpy( ssl->out_msg + i, crt->raw.p, n );
+        i += n; crt = crt->next;
+    }
+
+    ssl->out_msg[4]  = (unsigned char)( ( i - 7 ) >> 16 );
+    ssl->out_msg[5]  = (unsigned char)( ( i - 7 ) >>  8 );
+    ssl->out_msg[6]  = (unsigned char)( ( i - 7 )       );
+
+    ssl->out_msglen  = i;
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
+    ssl->out_msg[0]  = MBEDTLS_SSL_HS_CERTIFICATE;
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) && defined(MBEDTLS_SSL_CLI_C)
+write_msg:
+#endif
+
+    ssl->state++;
+
+    if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write certificate" ) );
+
+    return( ret );
+}
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
+
+#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+static int ssl_check_peer_crt_unchanged( mbedtls_ssl_context *ssl,
+                                         unsigned char *crt_buf,
+                                         size_t crt_buf_len )
+{
+    mbedtls_x509_crt const * const peer_crt = ssl->session->peer_cert;
+
+    if( peer_crt == NULL )
+        return( -1 );
+
+    if( peer_crt->raw.len != crt_buf_len )
+        return( -1 );
+
+    return( memcmp( peer_crt->raw.p, crt_buf, crt_buf_len ) );
+}
+#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+static int ssl_check_peer_crt_unchanged( mbedtls_ssl_context *ssl,
+                                         unsigned char *crt_buf,
+                                         size_t crt_buf_len )
+{
+    int ret;
+    unsigned char const * const peer_cert_digest =
+        ssl->session->peer_cert_digest;
+    mbedtls_md_type_t const peer_cert_digest_type =
+        ssl->session->peer_cert_digest_type;
+    mbedtls_md_info_t const * const digest_info =
+        mbedtls_md_info_from_type( peer_cert_digest_type );
+    unsigned char tmp_digest[MBEDTLS_SSL_PEER_CERT_DIGEST_MAX_LEN];
+    size_t digest_len;
+
+    if( peer_cert_digest == NULL || digest_info == NULL )
+        return( -1 );
+
+    digest_len = mbedtls_md_get_size( digest_info );
+    if( digest_len > MBEDTLS_SSL_PEER_CERT_DIGEST_MAX_LEN )
+        return( -1 );
+
+    ret = mbedtls_md( digest_info, crt_buf, crt_buf_len, tmp_digest );
+    if( ret != 0 )
+        return( -1 );
+
+    return( memcmp( tmp_digest, peer_cert_digest, digest_len ) );
+}
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+#endif /* MBEDTLS_SSL_RENEGOTIATION && MBEDTLS_SSL_CLI_C */
+
+/*
+ * Once the certificate message is read, parse it into a cert chain and
+ * perform basic checks, but leave actual verification to the caller
+ */
+static int ssl_parse_certificate_chain( mbedtls_ssl_context *ssl,
+                                        mbedtls_x509_crt *chain )
+{
+    int ret;
+#if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
+    int crt_cnt=0;
+#endif
+    size_t i, n;
+    uint8_t alert;
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    if( ssl->in_msg[0] != MBEDTLS_SSL_HS_CERTIFICATE ||
+        ssl->in_hslen < mbedtls_ssl_hs_hdr_len( ssl ) + 3 + 3 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
+    }
+
+    i = mbedtls_ssl_hs_hdr_len( ssl );
+
+    /*
+     * Same message structure as in mbedtls_ssl_write_certificate()
+     */
+    n = ( ssl->in_msg[i+1] << 8 ) | ssl->in_msg[i+2];
+
+    if( ssl->in_msg[i] != 0 ||
+        ssl->in_hslen != n + 3 + mbedtls_ssl_hs_hdr_len( ssl ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
+    }
+
+    /* Make &ssl->in_msg[i] point to the beginning of the CRT chain. */
+    i += 3;
+
+    /* Iterate through and parse the CRTs in the provided chain. */
+    while( i < ssl->in_hslen )
+    {
+        /* Check that there's room for the next CRT's length fields. */
+        if ( i + 3 > ssl->in_hslen ) {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
+            mbedtls_ssl_send_alert_message( ssl,
+                              MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                              MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
+        }
+        /* In theory, the CRT can be up to 2**24 Bytes, but we don't support
+         * anything beyond 2**16 ~ 64K. */
+        if( ssl->in_msg[i] != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
+            mbedtls_ssl_send_alert_message( ssl,
+                            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                            MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
+        }
+
+        /* Read length of the next CRT in the chain. */
+        n = ( (unsigned int) ssl->in_msg[i + 1] << 8 )
+            | (unsigned int) ssl->in_msg[i + 2];
+        i += 3;
+
+        if( n < 128 || i + n > ssl->in_hslen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
+            mbedtls_ssl_send_alert_message( ssl,
+                                 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                 MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
+        }
+
+        /* Check if we're handling the first CRT in the chain. */
+#if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
+        if( crt_cnt++ == 0 &&
+            ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
+            ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
+        {
+            /* During client-side renegotiation, check that the server's
+             * end-CRTs hasn't changed compared to the initial handshake,
+             * mitigating the triple handshake attack. On success, reuse
+             * the original end-CRT instead of parsing it again. */
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "Check that peer CRT hasn't changed during renegotiation" ) );
+            if( ssl_check_peer_crt_unchanged( ssl,
+                                              &ssl->in_msg[i],
+                                              n ) != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "new server cert during renegotiation" ) );
+                mbedtls_ssl_send_alert_message( ssl,
+                                                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED );
+                return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
+            }
+
+            /* Now we can safely free the original chain. */
+            ssl_clear_peer_cert( ssl->session );
+        }
+#endif /* MBEDTLS_SSL_RENEGOTIATION && MBEDTLS_SSL_CLI_C */
+
+        /* Parse the next certificate in the chain. */
+#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+        ret = mbedtls_x509_crt_parse_der( chain, ssl->in_msg + i, n );
+#else
+        /* If we don't need to store the CRT chain permanently, parse
+         * it in-place from the input buffer instead of making a copy. */
+        ret = mbedtls_x509_crt_parse_der_nocopy( chain, ssl->in_msg + i, n );
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+        switch( ret )
+        {
+            case 0: /*ok*/
+            case MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG + MBEDTLS_ERR_OID_NOT_FOUND:
+                /* Ignore certificate with an unknown algorithm: maybe a
+                   prior certificate was already trusted. */
+                break;
+
+            case MBEDTLS_ERR_X509_ALLOC_FAILED:
+                alert = MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR;
+                goto crt_parse_der_failed;
+
+            case MBEDTLS_ERR_X509_UNKNOWN_VERSION:
+                alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT;
+                goto crt_parse_der_failed;
+
+            default:
+                alert = MBEDTLS_SSL_ALERT_MSG_BAD_CERT;
+            crt_parse_der_failed:
+                mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, alert );
+                MBEDTLS_SSL_DEBUG_RET( 1, " mbedtls_x509_crt_parse_der", ret );
+                return( ret );
+        }
+
+        i += n;
+    }
+
+    MBEDTLS_SSL_DEBUG_CRT( 3, "peer certificate", chain );
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_SRV_C)
+static int ssl_srv_check_client_no_crt_notification( mbedtls_ssl_context *ssl )
+{
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+        return( -1 );
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+    /*
+     * Check if the client sent an empty certificate
+     */
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+    {
+        if( ssl->in_msglen  == 2                        &&
+            ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT            &&
+            ssl->in_msg[0]  == MBEDTLS_SSL_ALERT_LEVEL_WARNING  &&
+            ssl->in_msg[1]  == MBEDTLS_SSL_ALERT_MSG_NO_CERT )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "SSLv3 client has no certificate" ) );
+            return( 0 );
+        }
+
+        return( -1 );
+    }
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( ssl->in_hslen   == 3 + mbedtls_ssl_hs_hdr_len( ssl ) &&
+        ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE    &&
+        ssl->in_msg[0]  == MBEDTLS_SSL_HS_CERTIFICATE   &&
+        memcmp( ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl ), "\0\0\0", 3 ) == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLSv1 client has no certificate" ) );
+        return( 0 );
+    }
+
+    return( -1 );
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
+          MBEDTLS_SSL_PROTO_TLS1_2 */
+}
+#endif /* MBEDTLS_SSL_SRV_C */
+
+/* Check if a certificate message is expected.
+ * Return either
+ * - SSL_CERTIFICATE_EXPECTED, or
+ * - SSL_CERTIFICATE_SKIP
+ * indicating whether a Certificate message is expected or not.
+ */
+#define SSL_CERTIFICATE_EXPECTED 0
+#define SSL_CERTIFICATE_SKIP     1
+static int ssl_parse_certificate_coordinate( mbedtls_ssl_context *ssl,
+                                             int authmode )
+{
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->transform_negotiate->ciphersuite_info;
+
+    if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
+        return( SSL_CERTIFICATE_SKIP );
+
+#if defined(MBEDTLS_SSL_SRV_C)
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
+            return( SSL_CERTIFICATE_SKIP );
+
+        if( authmode == MBEDTLS_SSL_VERIFY_NONE )
+        {
+            ssl->session_negotiate->verify_result =
+                MBEDTLS_X509_BADCERT_SKIP_VERIFY;
+            return( SSL_CERTIFICATE_SKIP );
+        }
+    }
+#else
+    ((void) authmode);
+#endif /* MBEDTLS_SSL_SRV_C */
+
+    return( SSL_CERTIFICATE_EXPECTED );
+}
+
+static int ssl_parse_certificate_verify( mbedtls_ssl_context *ssl,
+                                         int authmode,
+                                         mbedtls_x509_crt *chain,
+                                         void *rs_ctx )
+{
+    int ret = 0;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->transform_negotiate->ciphersuite_info;
+    int have_ca_chain = 0;
+
+    int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *);
+    void *p_vrfy;
+
+    if( authmode == MBEDTLS_SSL_VERIFY_NONE )
+        return( 0 );
+
+    if( ssl->f_vrfy != NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "Use context-specific verification callback" ) );
+        f_vrfy = ssl->f_vrfy;
+        p_vrfy = ssl->p_vrfy;
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "Use configuration-specific verification callback" ) );
+        f_vrfy = ssl->conf->f_vrfy;
+        p_vrfy = ssl->conf->p_vrfy;
+    }
+
+    /*
+     * Main check: verify certificate
+     */
+#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
+    if( ssl->conf->f_ca_cb != NULL )
+    {
+        ((void) rs_ctx);
+        have_ca_chain = 1;
+
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "use CA callback for X.509 CRT verification" ) );
+        ret = mbedtls_x509_crt_verify_with_ca_cb(
+            chain,
+            ssl->conf->f_ca_cb,
+            ssl->conf->p_ca_cb,
+            ssl->conf->cert_profile,
+            ssl->hostname,
+            &ssl->session_negotiate->verify_result,
+            f_vrfy, p_vrfy );
+    }
+    else
+#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
+    {
+        mbedtls_x509_crt *ca_chain;
+        mbedtls_x509_crl *ca_crl;
+
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+        if( ssl->handshake->sni_ca_chain != NULL )
+        {
+            ca_chain = ssl->handshake->sni_ca_chain;
+            ca_crl   = ssl->handshake->sni_ca_crl;
+        }
+        else
+#endif
+        {
+            ca_chain = ssl->conf->ca_chain;
+            ca_crl   = ssl->conf->ca_crl;
+        }
+
+        if( ca_chain != NULL )
+            have_ca_chain = 1;
+
+        ret = mbedtls_x509_crt_verify_restartable(
+            chain,
+            ca_chain, ca_crl,
+            ssl->conf->cert_profile,
+            ssl->hostname,
+            &ssl->session_negotiate->verify_result,
+            f_vrfy, p_vrfy, rs_ctx );
+    }
+
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "x509_verify_cert", ret );
+    }
+
+#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
+    if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+        return( MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS );
+#endif
+
+    /*
+     * Secondary checks: always done, but change 'ret' only if it was 0
+     */
+
+#if defined(MBEDTLS_ECP_C)
+    {
+        const mbedtls_pk_context *pk = &chain->pk;
+
+        /* If certificate uses an EC key, make sure the curve is OK */
+        if( mbedtls_pk_can_do( pk, MBEDTLS_PK_ECKEY ) &&
+            mbedtls_ssl_check_curve( ssl, mbedtls_pk_ec( *pk )->grp.id ) != 0 )
+        {
+            ssl->session_negotiate->verify_result |= MBEDTLS_X509_BADCERT_BAD_KEY;
+
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (EC key curve)" ) );
+            if( ret == 0 )
+                ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE;
+        }
+    }
+#endif /* MBEDTLS_ECP_C */
+
+    if( mbedtls_ssl_check_cert_usage( chain,
+                                      ciphersuite_info,
+                                      ! ssl->conf->endpoint,
+                                      &ssl->session_negotiate->verify_result ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (usage extensions)" ) );
+        if( ret == 0 )
+            ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE;
+    }
+
+    /* mbedtls_x509_crt_verify_with_profile is supposed to report a
+     * verification failure through MBEDTLS_ERR_X509_CERT_VERIFY_FAILED,
+     * with details encoded in the verification flags. All other kinds
+     * of error codes, including those from the user provided f_vrfy
+     * functions, are treated as fatal and lead to a failure of
+     * ssl_parse_certificate even if verification was optional. */
+    if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL &&
+        ( ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED ||
+          ret == MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE ) )
+    {
+        ret = 0;
+    }
+
+    if( have_ca_chain == 0 && authmode == MBEDTLS_SSL_VERIFY_REQUIRED )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no CA chain" ) );
+        ret = MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED;
+    }
+
+    if( ret != 0 )
+    {
+        uint8_t alert;
+
+        /* The certificate may have been rejected for several reasons.
+           Pick one and send the corresponding alert. Which alert to send
+           may be a subject of debate in some cases. */
+        if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_OTHER )
+            alert = MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_CN_MISMATCH )
+            alert = MBEDTLS_SSL_ALERT_MSG_BAD_CERT;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_KEY_USAGE )
+            alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_EXT_KEY_USAGE )
+            alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_NS_CERT_TYPE )
+            alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_BAD_PK )
+            alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_BAD_KEY )
+            alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_EXPIRED )
+            alert = MBEDTLS_SSL_ALERT_MSG_CERT_EXPIRED;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_REVOKED )
+            alert = MBEDTLS_SSL_ALERT_MSG_CERT_REVOKED;
+        else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_NOT_TRUSTED )
+            alert = MBEDTLS_SSL_ALERT_MSG_UNKNOWN_CA;
+        else
+            alert = MBEDTLS_SSL_ALERT_MSG_CERT_UNKNOWN;
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        alert );
+    }
+
+#if defined(MBEDTLS_DEBUG_C)
+    if( ssl->session_negotiate->verify_result != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "! Certificate verification flags %x",
+                                    ssl->session_negotiate->verify_result ) );
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "Certificate verification flags clear" ) );
+    }
+#endif /* MBEDTLS_DEBUG_C */
+
+    return( ret );
+}
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+static int ssl_remember_peer_crt_digest( mbedtls_ssl_context *ssl,
+                                         unsigned char *start, size_t len )
+{
+    int ret;
+    /* Remember digest of the peer's end-CRT. */
+    ssl->session_negotiate->peer_cert_digest =
+        mbedtls_calloc( 1, MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN );
+    if( ssl->session_negotiate->peer_cert_digest == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
+                                    sizeof( MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN ) ) );
+        mbedtls_ssl_send_alert_message( ssl,
+                                        MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+
+    ret = mbedtls_md( mbedtls_md_info_from_type(
+                          MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE ),
+                      start, len,
+                      ssl->session_negotiate->peer_cert_digest );
+
+    ssl->session_negotiate->peer_cert_digest_type =
+        MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE;
+    ssl->session_negotiate->peer_cert_digest_len =
+        MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN;
+
+    return( ret );
+}
+
+static int ssl_remember_peer_pubkey( mbedtls_ssl_context *ssl,
+                                     unsigned char *start, size_t len )
+{
+    unsigned char *end = start + len;
+    int ret;
+
+    /* Make a copy of the peer's raw public key. */
+    mbedtls_pk_init( &ssl->handshake->peer_pubkey );
+    ret = mbedtls_pk_parse_subpubkey( &start, end,
+                                      &ssl->handshake->peer_pubkey );
+    if( ret != 0 )
+    {
+        /* We should have parsed the public key before. */
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    return( 0 );
+}
+#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
+{
+    int ret = 0;
+    int crt_expected;
+#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+    const int authmode = ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET
+                       ? ssl->handshake->sni_authmode
+                       : ssl->conf->authmode;
+#else
+    const int authmode = ssl->conf->authmode;
+#endif
+    void *rs_ctx = NULL;
+    mbedtls_x509_crt *chain = NULL;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
+
+    crt_expected = ssl_parse_certificate_coordinate( ssl, authmode );
+    if( crt_expected == SSL_CERTIFICATE_SKIP )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
+        goto exit;
+    }
+
+#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
+    if( ssl->handshake->ecrs_enabled &&
+        ssl->handshake->ecrs_state == ssl_ecrs_crt_verify )
+    {
+        chain = ssl->handshake->ecrs_peer_cert;
+        ssl->handshake->ecrs_peer_cert = NULL;
+        goto crt_verify;
+    }
+#endif
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        /* mbedtls_ssl_read_record may have sent an alert already. We
+           let it decide whether to alert. */
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        goto exit;
+    }
+
+#if defined(MBEDTLS_SSL_SRV_C)
+    if( ssl_srv_check_client_no_crt_notification( ssl ) == 0 )
+    {
+        ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_MISSING;
+
+        if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL )
+            ret = 0;
+        else
+            ret = MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE;
+
+        goto exit;
+    }
+#endif /* MBEDTLS_SSL_SRV_C */
+
+    /* Clear existing peer CRT structure in case we tried to
+     * reuse a session but it failed, and allocate a new one. */
+    ssl_clear_peer_cert( ssl->session_negotiate );
+
+    chain = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
+    if( chain == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
+                                    sizeof( mbedtls_x509_crt ) ) );
+        mbedtls_ssl_send_alert_message( ssl,
+                                        MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto exit;
+    }
+    mbedtls_x509_crt_init( chain );
+
+    ret = ssl_parse_certificate_chain( ssl, chain );
+    if( ret != 0 )
+        goto exit;
+
+#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
+    if( ssl->handshake->ecrs_enabled)
+        ssl->handshake->ecrs_state = ssl_ecrs_crt_verify;
+
+crt_verify:
+    if( ssl->handshake->ecrs_enabled)
+        rs_ctx = &ssl->handshake->ecrs_ctx;
+#endif
+
+    ret = ssl_parse_certificate_verify( ssl, authmode,
+                                        chain, rs_ctx );
+    if( ret != 0 )
+        goto exit;
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    {
+        unsigned char *crt_start, *pk_start;
+        size_t crt_len, pk_len;
+
+        /* We parse the CRT chain without copying, so
+         * these pointers point into the input buffer,
+         * and are hence still valid after freeing the
+         * CRT chain. */
+
+        crt_start = chain->raw.p;
+        crt_len   = chain->raw.len;
+
+        pk_start = chain->pk_raw.p;
+        pk_len   = chain->pk_raw.len;
+
+        /* Free the CRT structures before computing
+         * digest and copying the peer's public key. */
+        mbedtls_x509_crt_free( chain );
+        mbedtls_free( chain );
+        chain = NULL;
+
+        ret = ssl_remember_peer_crt_digest( ssl, crt_start, crt_len );
+        if( ret != 0 )
+            goto exit;
+
+        ret = ssl_remember_peer_pubkey( ssl, pk_start, pk_len );
+        if( ret != 0 )
+            goto exit;
+    }
+#else /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+    /* Pass ownership to session structure. */
+    ssl->session_negotiate->peer_cert = chain;
+    chain = NULL;
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate" ) );
+
+exit:
+
+    if( ret == 0 )
+        ssl->state++;
+
+#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
+    if( ret == MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS )
+    {
+        ssl->handshake->ecrs_peer_cert = chain;
+        chain = NULL;
+    }
+#endif
+
+    if( chain != NULL )
+    {
+        mbedtls_x509_crt_free( chain );
+        mbedtls_free( chain );
+    }
+
+    return( ret );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
+
+int mbedtls_ssl_write_change_cipher_spec( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write change cipher spec" ) );
+
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
+    ssl->out_msglen  = 1;
+    ssl->out_msg[0]  = 1;
+
+    ssl->state++;
+
+    if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write change cipher spec" ) );
+
+    return( 0 );
+}
+
+int mbedtls_ssl_parse_change_cipher_spec( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse change cipher spec" ) );
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        return( ret );
+    }
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad change cipher spec message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    /* CCS records are only accepted if they have length 1 and content '1',
+     * so we don't need to check this here. */
+
+    /*
+     * Switch to our negotiated transform and session parameters for inbound
+     * data.
+     */
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "switching to new transform spec for inbound data" ) );
+    ssl->transform_in = ssl->transform_negotiate;
+    ssl->session_in = ssl->session_negotiate;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+        ssl_dtls_replay_reset( ssl );
+#endif
+
+        /* Increment epoch */
+        if( ++ssl->in_epoch == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS epoch would wrap" ) );
+            /* This is highly unlikely to happen for legitimate reasons, so
+               treat it as an attack and don't send an alert. */
+            return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
+        }
+    }
+    else
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+    memset( ssl->in_ctr, 0, 8 );
+
+    ssl_update_in_pointers( ssl, ssl->transform_negotiate );
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_activate != NULL )
+    {
+        if( ( ret = mbedtls_ssl_hw_record_activate( ssl, MBEDTLS_SSL_CHANNEL_INBOUND ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_activate", ret );
+            mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                            MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+    }
+#endif
+
+    ssl->state++;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse change cipher spec" ) );
+
+    return( 0 );
+}
+
+void mbedtls_ssl_optimize_checksum( mbedtls_ssl_context *ssl,
+                            const mbedtls_ssl_ciphersuite_t *ciphersuite_info )
+{
+    ((void) ciphersuite_info);
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+    if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_3 )
+        ssl->handshake->update_checksum = ssl_update_checksum_md5sha1;
+    else
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA512_C)
+    if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
+        ssl->handshake->update_checksum = ssl_update_checksum_sha384;
+    else
+#endif
+#if defined(MBEDTLS_SHA256_C)
+    if( ciphersuite_info->mac != MBEDTLS_MD_SHA384 )
+        ssl->handshake->update_checksum = ssl_update_checksum_sha256;
+    else
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return;
+    }
+}
+
+void mbedtls_ssl_reset_checksum( mbedtls_ssl_context *ssl )
+{
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+     mbedtls_md5_starts_ret( &ssl->handshake->fin_md5  );
+    mbedtls_sha1_starts_ret( &ssl->handshake->fin_sha1 );
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_abort( &ssl->handshake->fin_sha256_psa );
+    psa_hash_setup( &ssl->handshake->fin_sha256_psa, PSA_ALG_SHA_256 );
+#else
+    mbedtls_sha256_starts_ret( &ssl->handshake->fin_sha256, 0 );
+#endif
+#endif
+#if defined(MBEDTLS_SHA512_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_abort( &ssl->handshake->fin_sha384_psa );
+    psa_hash_setup( &ssl->handshake->fin_sha384_psa, PSA_ALG_SHA_384 );
+#else
+    mbedtls_sha512_starts_ret( &ssl->handshake->fin_sha512, 1 );
+#endif
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+}
+
+static void ssl_update_checksum_start( mbedtls_ssl_context *ssl,
+                                       const unsigned char *buf, size_t len )
+{
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+     mbedtls_md5_update_ret( &ssl->handshake->fin_md5 , buf, len );
+    mbedtls_sha1_update_ret( &ssl->handshake->fin_sha1, buf, len );
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_update( &ssl->handshake->fin_sha256_psa, buf, len );
+#else
+    mbedtls_sha256_update_ret( &ssl->handshake->fin_sha256, buf, len );
+#endif
+#endif
+#if defined(MBEDTLS_SHA512_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_update( &ssl->handshake->fin_sha384_psa, buf, len );
+#else
+    mbedtls_sha512_update_ret( &ssl->handshake->fin_sha512, buf, len );
+#endif
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+}
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+static void ssl_update_checksum_md5sha1( mbedtls_ssl_context *ssl,
+                                         const unsigned char *buf, size_t len )
+{
+     mbedtls_md5_update_ret( &ssl->handshake->fin_md5 , buf, len );
+    mbedtls_sha1_update_ret( &ssl->handshake->fin_sha1, buf, len );
+}
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+static void ssl_update_checksum_sha256( mbedtls_ssl_context *ssl,
+                                        const unsigned char *buf, size_t len )
+{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_update( &ssl->handshake->fin_sha256_psa, buf, len );
+#else
+    mbedtls_sha256_update_ret( &ssl->handshake->fin_sha256, buf, len );
+#endif
+}
+#endif
+
+#if defined(MBEDTLS_SHA512_C)
+static void ssl_update_checksum_sha384( mbedtls_ssl_context *ssl,
+                                        const unsigned char *buf, size_t len )
+{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_update( &ssl->handshake->fin_sha384_psa, buf, len );
+#else
+    mbedtls_sha512_update_ret( &ssl->handshake->fin_sha512, buf, len );
+#endif
+}
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+static void ssl_calc_finished_ssl(
+                mbedtls_ssl_context *ssl, unsigned char *buf, int from )
+{
+    const char *sender;
+    mbedtls_md5_context  md5;
+    mbedtls_sha1_context sha1;
+
+    unsigned char padbuf[48];
+    unsigned char md5sum[16];
+    unsigned char sha1sum[20];
+
+    mbedtls_ssl_session *session = ssl->session_negotiate;
+    if( !session )
+        session = ssl->session;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished ssl" ) );
+
+    mbedtls_md5_init( &md5 );
+    mbedtls_sha1_init( &sha1 );
+
+    mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
+    mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
+
+    /*
+     * SSLv3:
+     *   hash =
+     *      MD5( master + pad2 +
+     *          MD5( handshake + sender + master + pad1 ) )
+     *   + SHA1( master + pad2 +
+     *         SHA1( handshake + sender + master + pad1 ) )
+     */
+
+#if !defined(MBEDTLS_MD5_ALT)
+    MBEDTLS_SSL_DEBUG_BUF( 4, "finished  md5 state", (unsigned char *)
+                    md5.state, sizeof(  md5.state ) );
+#endif
+
+#if !defined(MBEDTLS_SHA1_ALT)
+    MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha1 state", (unsigned char *)
+                   sha1.state, sizeof( sha1.state ) );
+#endif
+
+    sender = ( from == MBEDTLS_SSL_IS_CLIENT ) ? "CLNT"
+                                       : "SRVR";
+
+    memset( padbuf, 0x36, 48 );
+
+    mbedtls_md5_update_ret( &md5, (const unsigned char *) sender, 4 );
+    mbedtls_md5_update_ret( &md5, session->master, 48 );
+    mbedtls_md5_update_ret( &md5, padbuf, 48 );
+    mbedtls_md5_finish_ret( &md5, md5sum );
+
+    mbedtls_sha1_update_ret( &sha1, (const unsigned char *) sender, 4 );
+    mbedtls_sha1_update_ret( &sha1, session->master, 48 );
+    mbedtls_sha1_update_ret( &sha1, padbuf, 40 );
+    mbedtls_sha1_finish_ret( &sha1, sha1sum );
+
+    memset( padbuf, 0x5C, 48 );
+
+    mbedtls_md5_starts_ret( &md5 );
+    mbedtls_md5_update_ret( &md5, session->master, 48 );
+    mbedtls_md5_update_ret( &md5, padbuf, 48 );
+    mbedtls_md5_update_ret( &md5, md5sum, 16 );
+    mbedtls_md5_finish_ret( &md5, buf );
+
+    mbedtls_sha1_starts_ret( &sha1 );
+    mbedtls_sha1_update_ret( &sha1, session->master, 48 );
+    mbedtls_sha1_update_ret( &sha1, padbuf , 40 );
+    mbedtls_sha1_update_ret( &sha1, sha1sum, 20 );
+    mbedtls_sha1_finish_ret( &sha1, buf + 16 );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, 36 );
+
+    mbedtls_md5_free(  &md5  );
+    mbedtls_sha1_free( &sha1 );
+
+    mbedtls_platform_zeroize(  padbuf, sizeof(  padbuf ) );
+    mbedtls_platform_zeroize(  md5sum, sizeof(  md5sum ) );
+    mbedtls_platform_zeroize( sha1sum, sizeof( sha1sum ) );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
+}
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
+static void ssl_calc_finished_tls(
+                mbedtls_ssl_context *ssl, unsigned char *buf, int from )
+{
+    int len = 12;
+    const char *sender;
+    mbedtls_md5_context  md5;
+    mbedtls_sha1_context sha1;
+    unsigned char padbuf[36];
+
+    mbedtls_ssl_session *session = ssl->session_negotiate;
+    if( !session )
+        session = ssl->session;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished tls" ) );
+
+    mbedtls_md5_init( &md5 );
+    mbedtls_sha1_init( &sha1 );
+
+    mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
+    mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
+
+    /*
+     * TLSv1:
+     *   hash = PRF( master, finished_label,
+     *               MD5( handshake ) + SHA1( handshake ) )[0..11]
+     */
+
+#if !defined(MBEDTLS_MD5_ALT)
+    MBEDTLS_SSL_DEBUG_BUF( 4, "finished  md5 state", (unsigned char *)
+                    md5.state, sizeof(  md5.state ) );
+#endif
+
+#if !defined(MBEDTLS_SHA1_ALT)
+    MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha1 state", (unsigned char *)
+                   sha1.state, sizeof( sha1.state ) );
+#endif
+
+    sender = ( from == MBEDTLS_SSL_IS_CLIENT )
+             ? "client finished"
+             : "server finished";
+
+    mbedtls_md5_finish_ret(  &md5, padbuf );
+    mbedtls_sha1_finish_ret( &sha1, padbuf + 16 );
+
+    ssl->handshake->tls_prf( session->master, 48, sender,
+                             padbuf, 36, buf, len );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, len );
+
+    mbedtls_md5_free(  &md5  );
+    mbedtls_sha1_free( &sha1 );
+
+    mbedtls_platform_zeroize(  padbuf, sizeof(  padbuf ) );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+static void ssl_calc_finished_tls_sha256(
+                mbedtls_ssl_context *ssl, unsigned char *buf, int from )
+{
+    int len = 12;
+    const char *sender;
+    unsigned char padbuf[32];
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    size_t hash_size;
+    psa_hash_operation_t sha256_psa = PSA_HASH_OPERATION_INIT;
+    psa_status_t status;
+#else
+    mbedtls_sha256_context sha256;
+#endif
+
+    mbedtls_ssl_session *session = ssl->session_negotiate;
+    if( !session )
+        session = ssl->session;
+
+    sender = ( from == MBEDTLS_SSL_IS_CLIENT )
+             ? "client finished"
+             : "server finished";
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    sha256_psa = psa_hash_operation_init();
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc PSA finished tls sha256" ) );
+
+    status = psa_hash_clone( &ssl->handshake->fin_sha256_psa, &sha256_psa );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash clone failed" ) );
+        return;
+    }
+
+    status = psa_hash_finish( &sha256_psa, padbuf, sizeof( padbuf ), &hash_size );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash finish failed" ) );
+        return;
+    }
+    MBEDTLS_SSL_DEBUG_BUF( 3, "PSA calculated padbuf", padbuf, 32 );
+#else
+
+    mbedtls_sha256_init( &sha256 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished tls sha256" ) );
+
+    mbedtls_sha256_clone( &sha256, &ssl->handshake->fin_sha256 );
+
+    /*
+     * TLSv1.2:
+     *   hash = PRF( master, finished_label,
+     *               Hash( handshake ) )[0.11]
+     */
+
+#if !defined(MBEDTLS_SHA256_ALT)
+    MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha2 state", (unsigned char *)
+                   sha256.state, sizeof( sha256.state ) );
+#endif
+
+    mbedtls_sha256_finish_ret( &sha256, padbuf );
+    mbedtls_sha256_free( &sha256 );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    ssl->handshake->tls_prf( session->master, 48, sender,
+                             padbuf, 32, buf, len );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, len );
+
+    mbedtls_platform_zeroize(  padbuf, sizeof(  padbuf ) );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
+}
+#endif /* MBEDTLS_SHA256_C */
+
+#if defined(MBEDTLS_SHA512_C)
+static void ssl_calc_finished_tls_sha384(
+                mbedtls_ssl_context *ssl, unsigned char *buf, int from )
+{
+    int len = 12;
+    const char *sender;
+    unsigned char padbuf[48];
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    size_t hash_size;
+    psa_hash_operation_t sha384_psa = PSA_HASH_OPERATION_INIT;
+    psa_status_t status;
+#else
+    mbedtls_sha512_context sha512;
+#endif
+
+    mbedtls_ssl_session *session = ssl->session_negotiate;
+    if( !session )
+        session = ssl->session;
+
+    sender = ( from == MBEDTLS_SSL_IS_CLIENT )
+                ? "client finished"
+                : "server finished";
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    sha384_psa = psa_hash_operation_init();
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc PSA finished tls sha384" ) );
+
+    status = psa_hash_clone( &ssl->handshake->fin_sha384_psa, &sha384_psa );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash clone failed" ) );
+        return;
+    }
+
+    status = psa_hash_finish( &sha384_psa, padbuf, sizeof( padbuf ), &hash_size );
+    if( status != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "PSA hash finish failed" ) );
+        return;
+    }
+    MBEDTLS_SSL_DEBUG_BUF( 3, "PSA calculated padbuf", padbuf, 48 );
+#else
+    mbedtls_sha512_init( &sha512 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished tls sha384" ) );
+
+    mbedtls_sha512_clone( &sha512, &ssl->handshake->fin_sha512 );
+
+    /*
+     * TLSv1.2:
+     *   hash = PRF( master, finished_label,
+     *               Hash( handshake ) )[0.11]
+     */
+
+#if !defined(MBEDTLS_SHA512_ALT)
+    MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha512 state", (unsigned char *)
+                   sha512.state, sizeof( sha512.state ) );
+#endif
+
+    mbedtls_sha512_finish_ret( &sha512, padbuf );
+    mbedtls_sha512_free( &sha512 );
+#endif
+
+    ssl->handshake->tls_prf( session->master, 48, sender,
+                             padbuf, 48, buf, len );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, len );
+
+    mbedtls_platform_zeroize(  padbuf, sizeof( padbuf ) );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
+}
+#endif /* MBEDTLS_SHA512_C */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+static void ssl_handshake_wrapup_free_hs_transform( mbedtls_ssl_context *ssl )
+{
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "=> handshake wrapup: final free" ) );
+
+    /*
+     * Free our handshake params
+     */
+    mbedtls_ssl_handshake_free( ssl );
+    mbedtls_free( ssl->handshake );
+    ssl->handshake = NULL;
+
+    /*
+     * Free the previous transform and swith in the current one
+     */
+    if( ssl->transform )
+    {
+        mbedtls_ssl_transform_free( ssl->transform );
+        mbedtls_free( ssl->transform );
+    }
+    ssl->transform = ssl->transform_negotiate;
+    ssl->transform_negotiate = NULL;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "<= handshake wrapup: final free" ) );
+}
+
+void mbedtls_ssl_handshake_wrapup( mbedtls_ssl_context *ssl )
+{
+    int resume = ssl->handshake->resume;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "=> handshake wrapup" ) );
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
+    {
+        ssl->renego_status =  MBEDTLS_SSL_RENEGOTIATION_DONE;
+        ssl->renego_records_seen = 0;
+    }
+#endif
+
+    /*
+     * Free the previous session and switch in the current one
+     */
+    if( ssl->session )
+    {
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+        /* RFC 7366 3.1: keep the EtM state */
+        ssl->session_negotiate->encrypt_then_mac =
+                  ssl->session->encrypt_then_mac;
+#endif
+
+        mbedtls_ssl_session_free( ssl->session );
+        mbedtls_free( ssl->session );
+    }
+    ssl->session = ssl->session_negotiate;
+    ssl->session_negotiate = NULL;
+
+    /*
+     * Add cache entry
+     */
+    if( ssl->conf->f_set_cache != NULL &&
+        ssl->session->id_len != 0 &&
+        resume == 0 )
+    {
+        if( ssl->conf->f_set_cache( ssl->conf->p_cache, ssl->session ) != 0 )
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "cache did not store session" ) );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake->flight != NULL )
+    {
+        /* Cancel handshake timer */
+        ssl_set_timer( ssl, 0 );
+
+        /* Keep last flight around in case we need to resend it:
+         * we need the handshake and transform structures for that */
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip freeing handshake and transform" ) );
+    }
+    else
+#endif
+        ssl_handshake_wrapup_free_hs_transform( ssl );
+
+    ssl->state++;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "<= handshake wrapup" ) );
+}
+
+int mbedtls_ssl_write_finished( mbedtls_ssl_context *ssl )
+{
+    int ret, hash_len;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write finished" ) );
+
+    ssl_update_out_pointers( ssl, ssl->transform_negotiate );
+
+    ssl->handshake->calc_finished( ssl, ssl->out_msg + 4, ssl->conf->endpoint );
+
+    /*
+     * RFC 5246 7.4.9 (Page 63) says 12 is the default length and ciphersuites
+     * may define some other value. Currently (early 2016), no defined
+     * ciphersuite does this (and this is unlikely to change as activity has
+     * moved to TLS 1.3 now) so we can keep the hardcoded 12 here.
+     */
+    hash_len = ( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 ) ? 36 : 12;
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    ssl->verify_data_len = hash_len;
+    memcpy( ssl->own_verify_data, ssl->out_msg + 4, hash_len );
+#endif
+
+    ssl->out_msglen  = 4 + hash_len;
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
+    ssl->out_msg[0]  = MBEDTLS_SSL_HS_FINISHED;
+
+    /*
+     * In case of session resuming, invert the client and server
+     * ChangeCipherSpec messages order.
+     */
+    if( ssl->handshake->resume != 0 )
+    {
+#if defined(MBEDTLS_SSL_CLI_C)
+        if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+            ssl->state = MBEDTLS_SSL_HANDSHAKE_WRAPUP;
+#endif
+#if defined(MBEDTLS_SSL_SRV_C)
+        if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+            ssl->state = MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC;
+#endif
+    }
+    else
+        ssl->state++;
+
+    /*
+     * Switch to our negotiated transform and session parameters for outbound
+     * data.
+     */
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "switching to new transform spec for outbound data" ) );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        unsigned char i;
+
+        /* Remember current epoch settings for resending */
+        ssl->handshake->alt_transform_out = ssl->transform_out;
+        memcpy( ssl->handshake->alt_out_ctr, ssl->cur_out_ctr, 8 );
+
+        /* Set sequence_number to zero */
+        memset( ssl->cur_out_ctr + 2, 0, 6 );
+
+        /* Increment epoch */
+        for( i = 2; i > 0; i-- )
+            if( ++ssl->cur_out_ctr[i - 1] != 0 )
+                break;
+
+        /* The loop goes to its end iff the counter is wrapping */
+        if( i == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS epoch would wrap" ) );
+            return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
+        }
+    }
+    else
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+    memset( ssl->cur_out_ctr, 0, 8 );
+
+    ssl->transform_out = ssl->transform_negotiate;
+    ssl->session_out = ssl->session_negotiate;
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_activate != NULL )
+    {
+        if( ( ret = mbedtls_ssl_hw_record_activate( ssl, MBEDTLS_SSL_CHANNEL_OUTBOUND ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_activate", ret );
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+    }
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        mbedtls_ssl_send_flight_completed( ssl );
+#endif
+
+    if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
+        return( ret );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flight_transmit", ret );
+        return( ret );
+    }
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write finished" ) );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+#define SSL_MAX_HASH_LEN 36
+#else
+#define SSL_MAX_HASH_LEN 12
+#endif
+
+int mbedtls_ssl_parse_finished( mbedtls_ssl_context *ssl )
+{
+    int ret;
+    unsigned int hash_len;
+    unsigned char buf[SSL_MAX_HASH_LEN];
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse finished" ) );
+
+    ssl->handshake->calc_finished( ssl, buf, ssl->conf->endpoint ^ 1 );
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        return( ret );
+    }
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    /* There is currently no ciphersuite using another length with TLS 1.2 */
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+        hash_len = 36;
+    else
+#endif
+        hash_len = 12;
+
+    if( ssl->in_msg[0] != MBEDTLS_SSL_HS_FINISHED ||
+        ssl->in_hslen  != mbedtls_ssl_hs_hdr_len( ssl ) + hash_len )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_FINISHED );
+    }
+
+    if( mbedtls_ssl_safer_memcmp( ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl ),
+                      buf, hash_len ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_FINISHED );
+    }
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    ssl->verify_data_len = hash_len;
+    memcpy( ssl->peer_verify_data, buf, hash_len );
+#endif
+
+    if( ssl->handshake->resume != 0 )
+    {
+#if defined(MBEDTLS_SSL_CLI_C)
+        if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+            ssl->state = MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC;
+#endif
+#if defined(MBEDTLS_SSL_SRV_C)
+        if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+            ssl->state = MBEDTLS_SSL_HANDSHAKE_WRAPUP;
+#endif
+    }
+    else
+        ssl->state++;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        mbedtls_ssl_recv_flight_completed( ssl );
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse finished" ) );
+
+    return( 0 );
+}
+
+static void ssl_handshake_params_init( mbedtls_ssl_handshake_params *handshake )
+{
+    memset( handshake, 0, sizeof( mbedtls_ssl_handshake_params ) );
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+     mbedtls_md5_init(   &handshake->fin_md5  );
+    mbedtls_sha1_init(   &handshake->fin_sha1 );
+     mbedtls_md5_starts_ret( &handshake->fin_md5  );
+    mbedtls_sha1_starts_ret( &handshake->fin_sha1 );
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    handshake->fin_sha256_psa = psa_hash_operation_init();
+    psa_hash_setup( &handshake->fin_sha256_psa, PSA_ALG_SHA_256 );
+#else
+    mbedtls_sha256_init(   &handshake->fin_sha256    );
+    mbedtls_sha256_starts_ret( &handshake->fin_sha256, 0 );
+#endif
+#endif
+#if defined(MBEDTLS_SHA512_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    handshake->fin_sha384_psa = psa_hash_operation_init();
+    psa_hash_setup( &handshake->fin_sha384_psa, PSA_ALG_SHA_384 );
+#else
+    mbedtls_sha512_init(   &handshake->fin_sha512    );
+    mbedtls_sha512_starts_ret( &handshake->fin_sha512, 1 );
+#endif
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+    handshake->update_checksum = ssl_update_checksum_start;
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
+    defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+    mbedtls_ssl_sig_hash_set_init( &handshake->hash_algs );
+#endif
+
+#if defined(MBEDTLS_DHM_C)
+    mbedtls_dhm_init( &handshake->dhm_ctx );
+#endif
+#if defined(MBEDTLS_ECDH_C)
+    mbedtls_ecdh_init( &handshake->ecdh_ctx );
+#endif
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    mbedtls_ecjpake_init( &handshake->ecjpake_ctx );
+#if defined(MBEDTLS_SSL_CLI_C)
+    handshake->ecjpake_cache = NULL;
+    handshake->ecjpake_cache_len = 0;
+#endif
+#endif
+
+#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
+    mbedtls_x509_crt_restart_init( &handshake->ecrs_ctx );
+#endif
+
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+    handshake->sni_authmode = MBEDTLS_SSL_VERIFY_UNSET;
+#endif
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
+    !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    mbedtls_pk_init( &handshake->peer_pubkey );
+#endif
+}
+
+static void ssl_transform_init( mbedtls_ssl_transform *transform )
+{
+    memset( transform, 0, sizeof(mbedtls_ssl_transform) );
+
+    mbedtls_cipher_init( &transform->cipher_ctx_enc );
+    mbedtls_cipher_init( &transform->cipher_ctx_dec );
+
+    mbedtls_md_init( &transform->md_ctx_enc );
+    mbedtls_md_init( &transform->md_ctx_dec );
+}
+
+void mbedtls_ssl_session_init( mbedtls_ssl_session *session )
+{
+    memset( session, 0, sizeof(mbedtls_ssl_session) );
+}
+
+static int ssl_handshake_init( mbedtls_ssl_context *ssl )
+{
+    /* Clear old handshake information if present */
+    if( ssl->transform_negotiate )
+        mbedtls_ssl_transform_free( ssl->transform_negotiate );
+    if( ssl->session_negotiate )
+        mbedtls_ssl_session_free( ssl->session_negotiate );
+    if( ssl->handshake )
+        mbedtls_ssl_handshake_free( ssl );
+
+    /*
+     * Either the pointers are now NULL or cleared properly and can be freed.
+     * Now allocate missing structures.
+     */
+    if( ssl->transform_negotiate == NULL )
+    {
+        ssl->transform_negotiate = mbedtls_calloc( 1, sizeof(mbedtls_ssl_transform) );
+    }
+
+    if( ssl->session_negotiate == NULL )
+    {
+        ssl->session_negotiate = mbedtls_calloc( 1, sizeof(mbedtls_ssl_session) );
+    }
+
+    if( ssl->handshake == NULL )
+    {
+        ssl->handshake = mbedtls_calloc( 1, sizeof(mbedtls_ssl_handshake_params) );
+    }
+
+    /* All pointers should exist and can be directly freed without issue */
+    if( ssl->handshake == NULL ||
+        ssl->transform_negotiate == NULL ||
+        ssl->session_negotiate == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc() of ssl sub-contexts failed" ) );
+
+        mbedtls_free( ssl->handshake );
+        mbedtls_free( ssl->transform_negotiate );
+        mbedtls_free( ssl->session_negotiate );
+
+        ssl->handshake = NULL;
+        ssl->transform_negotiate = NULL;
+        ssl->session_negotiate = NULL;
+
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+
+    /* Initialize structures */
+    mbedtls_ssl_session_init( ssl->session_negotiate );
+    ssl_transform_init( ssl->transform_negotiate );
+    ssl_handshake_params_init( ssl->handshake );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        ssl->handshake->alt_transform_out = ssl->transform_out;
+
+        if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+            ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
+        else
+            ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
+
+        ssl_set_timer( ssl, 0 );
+    }
+#endif
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
+/* Dummy cookie callbacks for defaults */
+static int ssl_cookie_write_dummy( void *ctx,
+                      unsigned char **p, unsigned char *end,
+                      const unsigned char *cli_id, size_t cli_id_len )
+{
+    ((void) ctx);
+    ((void) p);
+    ((void) end);
+    ((void) cli_id);
+    ((void) cli_id_len);
+
+    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+}
+
+static int ssl_cookie_check_dummy( void *ctx,
+                      const unsigned char *cookie, size_t cookie_len,
+                      const unsigned char *cli_id, size_t cli_id_len )
+{
+    ((void) ctx);
+    ((void) cookie);
+    ((void) cookie_len);
+    ((void) cli_id);
+    ((void) cli_id_len);
+
+    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+}
+#endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY && MBEDTLS_SSL_SRV_C */
+
+/* Once ssl->out_hdr as the address of the beginning of the
+ * next outgoing record is set, deduce the other pointers.
+ *
+ * Note: For TLS, we save the implicit record sequence number
+ *       (entering MAC computation) in the 8 bytes before ssl->out_hdr,
+ *       and the caller has to make sure there's space for this.
+ */
+
+static void ssl_update_out_pointers( mbedtls_ssl_context *ssl,
+                                     mbedtls_ssl_transform *transform )
+{
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        ssl->out_ctr = ssl->out_hdr +  3;
+        ssl->out_len = ssl->out_hdr + 11;
+        ssl->out_iv  = ssl->out_hdr + 13;
+    }
+    else
+#endif
+    {
+        ssl->out_ctr = ssl->out_hdr - 8;
+        ssl->out_len = ssl->out_hdr + 3;
+        ssl->out_iv  = ssl->out_hdr + 5;
+    }
+
+    /* Adjust out_msg to make space for explicit IV, if used. */
+    if( transform != NULL &&
+        ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
+    {
+        ssl->out_msg = ssl->out_iv + transform->ivlen - transform->fixed_ivlen;
+    }
+    else
+        ssl->out_msg = ssl->out_iv;
+}
+
+/* Once ssl->in_hdr as the address of the beginning of the
+ * next incoming record is set, deduce the other pointers.
+ *
+ * Note: For TLS, we save the implicit record sequence number
+ *       (entering MAC computation) in the 8 bytes before ssl->in_hdr,
+ *       and the caller has to make sure there's space for this.
+ */
+
+static void ssl_update_in_pointers( mbedtls_ssl_context *ssl,
+                                    mbedtls_ssl_transform *transform )
+{
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        ssl->in_ctr = ssl->in_hdr +  3;
+        ssl->in_len = ssl->in_hdr + 11;
+        ssl->in_iv  = ssl->in_hdr + 13;
+    }
+    else
+#endif
+    {
+        ssl->in_ctr = ssl->in_hdr - 8;
+        ssl->in_len = ssl->in_hdr + 3;
+        ssl->in_iv  = ssl->in_hdr + 5;
+    }
+
+    /* Offset in_msg from in_iv to allow space for explicit IV, if used. */
+    if( transform != NULL &&
+        ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
+    {
+        ssl->in_msg = ssl->in_iv + transform->ivlen - transform->fixed_ivlen;
+    }
+    else
+        ssl->in_msg = ssl->in_iv;
+}
+
+/*
+ * Initialize an SSL context
+ */
+void mbedtls_ssl_init( mbedtls_ssl_context *ssl )
+{
+    memset( ssl, 0, sizeof( mbedtls_ssl_context ) );
+}
+
+/*
+ * Setup an SSL context
+ */
+
+static void ssl_reset_in_out_pointers( mbedtls_ssl_context *ssl )
+{
+    /* Set the incoming and outgoing record pointers. */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        ssl->out_hdr = ssl->out_buf;
+        ssl->in_hdr  = ssl->in_buf;
+    }
+    else
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+    {
+        ssl->out_hdr = ssl->out_buf + 8;
+        ssl->in_hdr  = ssl->in_buf  + 8;
+    }
+
+    /* Derive other internal pointers. */
+    ssl_update_out_pointers( ssl, NULL /* no transform enabled */ );
+    ssl_update_in_pointers ( ssl, NULL /* no transform enabled */ );
+}
+
+int mbedtls_ssl_setup( mbedtls_ssl_context *ssl,
+                       const mbedtls_ssl_config *conf )
+{
+    int ret;
+
+    ssl->conf = conf;
+
+    /*
+     * Prepare base structures
+     */
+
+    /* Set to NULL in case of an error condition */
+    ssl->out_buf = NULL;
+
+    ssl->in_buf = mbedtls_calloc( 1, MBEDTLS_SSL_IN_BUFFER_LEN );
+    if( ssl->in_buf == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed", MBEDTLS_SSL_IN_BUFFER_LEN) );
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto error;
+    }
+
+    ssl->out_buf = mbedtls_calloc( 1, MBEDTLS_SSL_OUT_BUFFER_LEN );
+    if( ssl->out_buf == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed", MBEDTLS_SSL_OUT_BUFFER_LEN) );
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto error;
+    }
+
+    ssl_reset_in_out_pointers( ssl );
+
+    if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
+        goto error;
+
+    return( 0 );
+
+error:
+    mbedtls_free( ssl->in_buf );
+    mbedtls_free( ssl->out_buf );
+
+    ssl->conf = NULL;
+
+    ssl->in_buf = NULL;
+    ssl->out_buf = NULL;
+
+    ssl->in_hdr = NULL;
+    ssl->in_ctr = NULL;
+    ssl->in_len = NULL;
+    ssl->in_iv = NULL;
+    ssl->in_msg = NULL;
+
+    ssl->out_hdr = NULL;
+    ssl->out_ctr = NULL;
+    ssl->out_len = NULL;
+    ssl->out_iv = NULL;
+    ssl->out_msg = NULL;
+
+    return( ret );
+}
+
+/*
+ * Reset an initialized and used SSL context for re-use while retaining
+ * all application-set variables, function pointers and data.
+ *
+ * If partial is non-zero, keep data in the input buffer and client ID.
+ * (Use when a DTLS client reconnects from the same port.)
+ */
+static int ssl_session_reset_int( mbedtls_ssl_context *ssl, int partial )
+{
+    int ret;
+
+#if !defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) ||     \
+    !defined(MBEDTLS_SSL_SRV_C)
+    ((void) partial);
+#endif
+
+    ssl->state = MBEDTLS_SSL_HELLO_REQUEST;
+
+    /* Cancel any possibly running timer */
+    ssl_set_timer( ssl, 0 );
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    ssl->renego_status = MBEDTLS_SSL_INITIAL_HANDSHAKE;
+    ssl->renego_records_seen = 0;
+
+    ssl->verify_data_len = 0;
+    memset( ssl->own_verify_data, 0, MBEDTLS_SSL_VERIFY_DATA_MAX_LEN );
+    memset( ssl->peer_verify_data, 0, MBEDTLS_SSL_VERIFY_DATA_MAX_LEN );
+#endif
+    ssl->secure_renegotiation = MBEDTLS_SSL_LEGACY_RENEGOTIATION;
+
+    ssl->in_offt = NULL;
+    ssl_reset_in_out_pointers( ssl );
+
+    ssl->in_msgtype = 0;
+    ssl->in_msglen = 0;
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    ssl->next_record_offset = 0;
+    ssl->in_epoch = 0;
+#endif
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+    ssl_dtls_replay_reset( ssl );
+#endif
+
+    ssl->in_hslen = 0;
+    ssl->nb_zero = 0;
+
+    ssl->keep_current_message = 0;
+
+    ssl->out_msgtype = 0;
+    ssl->out_msglen = 0;
+    ssl->out_left = 0;
+#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
+    if( ssl->split_done != MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED )
+        ssl->split_done = 0;
+#endif
+
+    memset( ssl->cur_out_ctr, 0, sizeof( ssl->cur_out_ctr ) );
+
+    ssl->transform_in = NULL;
+    ssl->transform_out = NULL;
+
+    ssl->session_in = NULL;
+    ssl->session_out = NULL;
+
+    memset( ssl->out_buf, 0, MBEDTLS_SSL_OUT_BUFFER_LEN );
+
+#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
+    if( partial == 0 )
+#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
+    {
+        ssl->in_left = 0;
+        memset( ssl->in_buf, 0, MBEDTLS_SSL_IN_BUFFER_LEN );
+    }
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_reset != NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_reset()" ) );
+        if( ( ret = mbedtls_ssl_hw_record_reset( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_reset", ret );
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+    }
+#endif
+
+    if( ssl->transform )
+    {
+        mbedtls_ssl_transform_free( ssl->transform );
+        mbedtls_free( ssl->transform );
+        ssl->transform = NULL;
+    }
+
+    if( ssl->session )
+    {
+        mbedtls_ssl_session_free( ssl->session );
+        mbedtls_free( ssl->session );
+        ssl->session = NULL;
+    }
+
+#if defined(MBEDTLS_SSL_ALPN)
+    ssl->alpn_chosen = NULL;
+#endif
+
+#if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
+#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE)
+    if( partial == 0 )
+#endif
+    {
+        mbedtls_free( ssl->cli_id );
+        ssl->cli_id = NULL;
+        ssl->cli_id_len = 0;
+    }
+#endif
+
+    if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
+        return( ret );
+
+    return( 0 );
+}
+
+/*
+ * Reset an initialized and used SSL context for re-use while retaining
+ * all application-set variables, function pointers and data.
+ */
+int mbedtls_ssl_session_reset( mbedtls_ssl_context *ssl )
+{
+    return( ssl_session_reset_int( ssl, 0 ) );
+}
+
+/*
+ * SSL set accessors
+ */
+void mbedtls_ssl_conf_endpoint( mbedtls_ssl_config *conf, int endpoint )
+{
+    conf->endpoint   = endpoint;
+}
+
+void mbedtls_ssl_conf_transport( mbedtls_ssl_config *conf, int transport )
+{
+    conf->transport = transport;
+}
+
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+void mbedtls_ssl_conf_dtls_anti_replay( mbedtls_ssl_config *conf, char mode )
+{
+    conf->anti_replay = mode;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_DTLS_BADMAC_LIMIT)
+void mbedtls_ssl_conf_dtls_badmac_limit( mbedtls_ssl_config *conf, unsigned limit )
+{
+    conf->badmac_limit = limit;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+
+void mbedtls_ssl_set_datagram_packing( mbedtls_ssl_context *ssl,
+                                       unsigned allow_packing )
+{
+    ssl->disable_datagram_packing = !allow_packing;
+}
+
+void mbedtls_ssl_conf_handshake_timeout( mbedtls_ssl_config *conf,
+                                         uint32_t min, uint32_t max )
+{
+    conf->hs_timeout_min = min;
+    conf->hs_timeout_max = max;
+}
+#endif
+
+void mbedtls_ssl_conf_authmode( mbedtls_ssl_config *conf, int authmode )
+{
+    conf->authmode   = authmode;
+}
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+void mbedtls_ssl_conf_verify( mbedtls_ssl_config *conf,
+                     int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+                     void *p_vrfy )
+{
+    conf->f_vrfy      = f_vrfy;
+    conf->p_vrfy      = p_vrfy;
+}
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+void mbedtls_ssl_conf_rng( mbedtls_ssl_config *conf,
+                  int (*f_rng)(void *, unsigned char *, size_t),
+                  void *p_rng )
+{
+    conf->f_rng      = f_rng;
+    conf->p_rng      = p_rng;
+}
+
+void mbedtls_ssl_conf_dbg( mbedtls_ssl_config *conf,
+                  void (*f_dbg)(void *, int, const char *, int, const char *),
+                  void  *p_dbg )
+{
+    conf->f_dbg      = f_dbg;
+    conf->p_dbg      = p_dbg;
+}
+
+void mbedtls_ssl_set_bio( mbedtls_ssl_context *ssl,
+        void *p_bio,
+        mbedtls_ssl_send_t *f_send,
+        mbedtls_ssl_recv_t *f_recv,
+        mbedtls_ssl_recv_timeout_t *f_recv_timeout )
+{
+    ssl->p_bio          = p_bio;
+    ssl->f_send         = f_send;
+    ssl->f_recv         = f_recv;
+    ssl->f_recv_timeout = f_recv_timeout;
+}
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+void mbedtls_ssl_set_mtu( mbedtls_ssl_context *ssl, uint16_t mtu )
+{
+    ssl->mtu = mtu;
+}
+#endif
+
+void mbedtls_ssl_conf_read_timeout( mbedtls_ssl_config *conf, uint32_t timeout )
+{
+    conf->read_timeout   = timeout;
+}
+
+void mbedtls_ssl_set_timer_cb( mbedtls_ssl_context *ssl,
+                               void *p_timer,
+                               mbedtls_ssl_set_timer_t *f_set_timer,
+                               mbedtls_ssl_get_timer_t *f_get_timer )
+{
+    ssl->p_timer        = p_timer;
+    ssl->f_set_timer    = f_set_timer;
+    ssl->f_get_timer    = f_get_timer;
+
+    /* Make sure we start with no timer running */
+    ssl_set_timer( ssl, 0 );
+}
+
+#if defined(MBEDTLS_SSL_SRV_C)
+void mbedtls_ssl_conf_session_cache( mbedtls_ssl_config *conf,
+        void *p_cache,
+        int (*f_get_cache)(void *, mbedtls_ssl_session *),
+        int (*f_set_cache)(void *, const mbedtls_ssl_session *) )
+{
+    conf->p_cache = p_cache;
+    conf->f_get_cache = f_get_cache;
+    conf->f_set_cache = f_set_cache;
+}
+#endif /* MBEDTLS_SSL_SRV_C */
+
+#if defined(MBEDTLS_SSL_CLI_C)
+int mbedtls_ssl_set_session( mbedtls_ssl_context *ssl, const mbedtls_ssl_session *session )
+{
+    int ret;
+
+    if( ssl == NULL ||
+        session == NULL ||
+        ssl->session_negotiate == NULL ||
+        ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT )
+    {
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    if( ( ret = mbedtls_ssl_session_copy( ssl->session_negotiate,
+                                          session ) ) != 0 )
+        return( ret );
+
+    ssl->handshake->resume = 1;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_CLI_C */
+
+void mbedtls_ssl_conf_ciphersuites( mbedtls_ssl_config *conf,
+                                   const int *ciphersuites )
+{
+    conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_0] = ciphersuites;
+    conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_1] = ciphersuites;
+    conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_2] = ciphersuites;
+    conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_3] = ciphersuites;
+}
+
+void mbedtls_ssl_conf_ciphersuites_for_version( mbedtls_ssl_config *conf,
+                                       const int *ciphersuites,
+                                       int major, int minor )
+{
+    if( major != MBEDTLS_SSL_MAJOR_VERSION_3 )
+        return;
+
+    if( minor < MBEDTLS_SSL_MINOR_VERSION_0 || minor > MBEDTLS_SSL_MINOR_VERSION_3 )
+        return;
+
+    conf->ciphersuite_list[minor] = ciphersuites;
+}
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+void mbedtls_ssl_conf_cert_profile( mbedtls_ssl_config *conf,
+                                    const mbedtls_x509_crt_profile *profile )
+{
+    conf->cert_profile = profile;
+}
+
+/* Append a new keycert entry to a (possibly empty) list */
+static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
+                                mbedtls_x509_crt *cert,
+                                mbedtls_pk_context *key )
+{
+    mbedtls_ssl_key_cert *new_cert;
+
+    new_cert = mbedtls_calloc( 1, sizeof( mbedtls_ssl_key_cert ) );
+    if( new_cert == NULL )
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+
+    new_cert->cert = cert;
+    new_cert->key  = key;
+    new_cert->next = NULL;
+
+    /* Update head is the list was null, else add to the end */
+    if( *head == NULL )
+    {
+        *head = new_cert;
+    }
+    else
+    {
+        mbedtls_ssl_key_cert *cur = *head;
+        while( cur->next != NULL )
+            cur = cur->next;
+        cur->next = new_cert;
+    }
+
+    return( 0 );
+}
+
+int mbedtls_ssl_conf_own_cert( mbedtls_ssl_config *conf,
+                              mbedtls_x509_crt *own_cert,
+                              mbedtls_pk_context *pk_key )
+{
+    return( ssl_append_key_cert( &conf->key_cert, own_cert, pk_key ) );
+}
+
+void mbedtls_ssl_conf_ca_chain( mbedtls_ssl_config *conf,
+                               mbedtls_x509_crt *ca_chain,
+                               mbedtls_x509_crl *ca_crl )
+{
+    conf->ca_chain   = ca_chain;
+    conf->ca_crl     = ca_crl;
+
+#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
+    /* mbedtls_ssl_conf_ca_chain() and mbedtls_ssl_conf_ca_cb()
+     * cannot be used together. */
+    conf->f_ca_cb = NULL;
+    conf->p_ca_cb = NULL;
+#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
+}
+
+#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
+void mbedtls_ssl_conf_ca_cb( mbedtls_ssl_config *conf,
+                             mbedtls_x509_crt_ca_cb_t f_ca_cb,
+                             void *p_ca_cb )
+{
+    conf->f_ca_cb = f_ca_cb;
+    conf->p_ca_cb = p_ca_cb;
+
+    /* mbedtls_ssl_conf_ca_chain() and mbedtls_ssl_conf_ca_cb()
+     * cannot be used together. */
+    conf->ca_chain   = NULL;
+    conf->ca_crl     = NULL;
+}
+#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+int mbedtls_ssl_set_hs_own_cert( mbedtls_ssl_context *ssl,
+                                 mbedtls_x509_crt *own_cert,
+                                 mbedtls_pk_context *pk_key )
+{
+    return( ssl_append_key_cert( &ssl->handshake->sni_key_cert,
+                                 own_cert, pk_key ) );
+}
+
+void mbedtls_ssl_set_hs_ca_chain( mbedtls_ssl_context *ssl,
+                                  mbedtls_x509_crt *ca_chain,
+                                  mbedtls_x509_crl *ca_crl )
+{
+    ssl->handshake->sni_ca_chain   = ca_chain;
+    ssl->handshake->sni_ca_crl     = ca_crl;
+}
+
+void mbedtls_ssl_set_hs_authmode( mbedtls_ssl_context *ssl,
+                                  int authmode )
+{
+    ssl->handshake->sni_authmode = authmode;
+}
+#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+void mbedtls_ssl_set_verify( mbedtls_ssl_context *ssl,
+                     int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+                     void *p_vrfy )
+{
+    ssl->f_vrfy = f_vrfy;
+    ssl->p_vrfy = p_vrfy;
+}
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+/*
+ * Set EC J-PAKE password for current handshake
+ */
+int mbedtls_ssl_set_hs_ecjpake_password( mbedtls_ssl_context *ssl,
+                                         const unsigned char *pw,
+                                         size_t pw_len )
+{
+    mbedtls_ecjpake_role role;
+
+    if( ssl->handshake == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+        role = MBEDTLS_ECJPAKE_SERVER;
+    else
+        role = MBEDTLS_ECJPAKE_CLIENT;
+
+    return( mbedtls_ecjpake_setup( &ssl->handshake->ecjpake_ctx,
+                                   role,
+                                   MBEDTLS_MD_SHA256,
+                                   MBEDTLS_ECP_DP_SECP256R1,
+                                   pw, pw_len ) );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
+
+static void ssl_conf_remove_psk( mbedtls_ssl_config *conf )
+{
+    /* Remove reference to existing PSK, if any. */
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    if( conf->psk_opaque != 0 )
+    {
+        /* The maintenance of the PSK key slot is the
+         * user's responsibility. */
+        conf->psk_opaque = 0;
+    }
+    /* This and the following branch should never
+     * be taken simultaenously as we maintain the
+     * invariant that raw and opaque PSKs are never
+     * configured simultaneously. As a safeguard,
+     * though, `else` is omitted here. */
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    if( conf->psk != NULL )
+    {
+        mbedtls_platform_zeroize( conf->psk, conf->psk_len );
+
+        mbedtls_free( conf->psk );
+        conf->psk = NULL;
+        conf->psk_len = 0;
+    }
+
+    /* Remove reference to PSK identity, if any. */
+    if( conf->psk_identity != NULL )
+    {
+        mbedtls_free( conf->psk_identity );
+        conf->psk_identity = NULL;
+        conf->psk_identity_len = 0;
+    }
+}
+
+/* This function assumes that PSK identity in the SSL config is unset.
+ * It checks that the provided identity is well-formed and attempts
+ * to make a copy of it in the SSL config.
+ * On failure, the PSK identity in the config remains unset. */
+static int ssl_conf_set_psk_identity( mbedtls_ssl_config *conf,
+                                      unsigned char const *psk_identity,
+                                      size_t psk_identity_len )
+{
+    /* Identity len will be encoded on two bytes */
+    if( psk_identity               == NULL ||
+        ( psk_identity_len >> 16 ) != 0    ||
+        psk_identity_len > MBEDTLS_SSL_OUT_CONTENT_LEN )
+    {
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    conf->psk_identity = mbedtls_calloc( 1, psk_identity_len );
+    if( conf->psk_identity == NULL )
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+
+    conf->psk_identity_len = psk_identity_len;
+    memcpy( conf->psk_identity, psk_identity, conf->psk_identity_len );
+
+    return( 0 );
+}
+
+int mbedtls_ssl_conf_psk( mbedtls_ssl_config *conf,
+                const unsigned char *psk, size_t psk_len,
+                const unsigned char *psk_identity, size_t psk_identity_len )
+{
+    int ret;
+    /* Remove opaque/raw PSK + PSK Identity */
+    ssl_conf_remove_psk( conf );
+
+    /* Check and set raw PSK */
+    if( psk == NULL || psk_len > MBEDTLS_PSK_MAX_LEN )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    if( ( conf->psk = mbedtls_calloc( 1, psk_len ) ) == NULL )
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    conf->psk_len = psk_len;
+    memcpy( conf->psk, psk, conf->psk_len );
+
+    /* Check and set PSK Identity */
+    ret = ssl_conf_set_psk_identity( conf, psk_identity, psk_identity_len );
+    if( ret != 0 )
+        ssl_conf_remove_psk( conf );
+
+    return( ret );
+}
+
+static void ssl_remove_psk( mbedtls_ssl_context *ssl )
+{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    if( ssl->handshake->psk_opaque != 0 )
+    {
+        ssl->handshake->psk_opaque = 0;
+    }
+    else
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    if( ssl->handshake->psk != NULL )
+    {
+        mbedtls_platform_zeroize( ssl->handshake->psk,
+                                  ssl->handshake->psk_len );
+        mbedtls_free( ssl->handshake->psk );
+        ssl->handshake->psk_len = 0;
+    }
+}
+
+int mbedtls_ssl_set_hs_psk( mbedtls_ssl_context *ssl,
+                            const unsigned char *psk, size_t psk_len )
+{
+    if( psk == NULL || ssl->handshake == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    if( psk_len > MBEDTLS_PSK_MAX_LEN )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    ssl_remove_psk( ssl );
+
+    if( ( ssl->handshake->psk = mbedtls_calloc( 1, psk_len ) ) == NULL )
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+
+    ssl->handshake->psk_len = psk_len;
+    memcpy( ssl->handshake->psk, psk, ssl->handshake->psk_len );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+int mbedtls_ssl_conf_psk_opaque( mbedtls_ssl_config *conf,
+                                 psa_key_handle_t psk_slot,
+                                 const unsigned char *psk_identity,
+                                 size_t psk_identity_len )
+{
+    int ret;
+    /* Clear opaque/raw PSK + PSK Identity, if present. */
+    ssl_conf_remove_psk( conf );
+
+    /* Check and set opaque PSK */
+    if( psk_slot == 0 )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    conf->psk_opaque = psk_slot;
+
+    /* Check and set PSK Identity */
+    ret = ssl_conf_set_psk_identity( conf, psk_identity,
+                                     psk_identity_len );
+    if( ret != 0 )
+        ssl_conf_remove_psk( conf );
+
+    return( ret );
+}
+
+int mbedtls_ssl_set_hs_psk_opaque( mbedtls_ssl_context *ssl,
+                                   psa_key_handle_t psk_slot )
+{
+    if( psk_slot == 0 || ssl->handshake == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    ssl_remove_psk( ssl );
+    ssl->handshake->psk_opaque = psk_slot;
+    return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+void mbedtls_ssl_conf_psk_cb( mbedtls_ssl_config *conf,
+                     int (*f_psk)(void *, mbedtls_ssl_context *, const unsigned char *,
+                     size_t),
+                     void *p_psk )
+{
+    conf->f_psk = f_psk;
+    conf->p_psk = p_psk;
+}
+#endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
+
+#if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+int mbedtls_ssl_conf_dh_param( mbedtls_ssl_config *conf, const char *dhm_P, const char *dhm_G )
+{
+    int ret;
+
+    if( ( ret = mbedtls_mpi_read_string( &conf->dhm_P, 16, dhm_P ) ) != 0 ||
+        ( ret = mbedtls_mpi_read_string( &conf->dhm_G, 16, dhm_G ) ) != 0 )
+    {
+        mbedtls_mpi_free( &conf->dhm_P );
+        mbedtls_mpi_free( &conf->dhm_G );
+        return( ret );
+    }
+
+    return( 0 );
+}
+#endif /* MBEDTLS_DEPRECATED_REMOVED */
+
+int mbedtls_ssl_conf_dh_param_bin( mbedtls_ssl_config *conf,
+                                   const unsigned char *dhm_P, size_t P_len,
+                                   const unsigned char *dhm_G, size_t G_len )
+{
+    int ret;
+
+    if( ( ret = mbedtls_mpi_read_binary( &conf->dhm_P, dhm_P, P_len ) ) != 0 ||
+        ( ret = mbedtls_mpi_read_binary( &conf->dhm_G, dhm_G, G_len ) ) != 0 )
+    {
+        mbedtls_mpi_free( &conf->dhm_P );
+        mbedtls_mpi_free( &conf->dhm_G );
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_ssl_conf_dh_param_ctx( mbedtls_ssl_config *conf, mbedtls_dhm_context *dhm_ctx )
+{
+    int ret;
+
+    if( ( ret = mbedtls_mpi_copy( &conf->dhm_P, &dhm_ctx->P ) ) != 0 ||
+        ( ret = mbedtls_mpi_copy( &conf->dhm_G, &dhm_ctx->G ) ) != 0 )
+    {
+        mbedtls_mpi_free( &conf->dhm_P );
+        mbedtls_mpi_free( &conf->dhm_G );
+        return( ret );
+    }
+
+    return( 0 );
+}
+#endif /* MBEDTLS_DHM_C && MBEDTLS_SSL_SRV_C */
+
+#if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
+/*
+ * Set the minimum length for Diffie-Hellman parameters
+ */
+void mbedtls_ssl_conf_dhm_min_bitlen( mbedtls_ssl_config *conf,
+                                      unsigned int bitlen )
+{
+    conf->dhm_min_bitlen = bitlen;
+}
+#endif /* MBEDTLS_DHM_C && MBEDTLS_SSL_CLI_C */
+
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+/*
+ * Set allowed/preferred hashes for handshake signatures
+ */
+void mbedtls_ssl_conf_sig_hashes( mbedtls_ssl_config *conf,
+                                  const int *hashes )
+{
+    conf->sig_hashes = hashes;
+}
+#endif /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
+
+#if defined(MBEDTLS_ECP_C)
+/*
+ * Set the allowed elliptic curves
+ */
+void mbedtls_ssl_conf_curves( mbedtls_ssl_config *conf,
+                             const mbedtls_ecp_group_id *curve_list )
+{
+    conf->curve_list = curve_list;
+}
+#endif /* MBEDTLS_ECP_C */
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+int mbedtls_ssl_set_hostname( mbedtls_ssl_context *ssl, const char *hostname )
+{
+    /* Initialize to suppress unnecessary compiler warning */
+    size_t hostname_len = 0;
+
+    /* Check if new hostname is valid before
+     * making any change to current one */
+    if( hostname != NULL )
+    {
+        hostname_len = strlen( hostname );
+
+        if( hostname_len > MBEDTLS_SSL_MAX_HOST_NAME_LEN )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    /* Now it's clear that we will overwrite the old hostname,
+     * so we can free it safely */
+
+    if( ssl->hostname != NULL )
+    {
+        mbedtls_platform_zeroize( ssl->hostname, strlen( ssl->hostname ) );
+        mbedtls_free( ssl->hostname );
+    }
+
+    /* Passing NULL as hostname shall clear the old one */
+
+    if( hostname == NULL )
+    {
+        ssl->hostname = NULL;
+    }
+    else
+    {
+        ssl->hostname = mbedtls_calloc( 1, hostname_len + 1 );
+        if( ssl->hostname == NULL )
+            return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+
+        memcpy( ssl->hostname, hostname, hostname_len );
+
+        ssl->hostname[hostname_len] = '\0';
+    }
+
+    return( 0 );
+}
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+void mbedtls_ssl_conf_sni( mbedtls_ssl_config *conf,
+                  int (*f_sni)(void *, mbedtls_ssl_context *,
+                                const unsigned char *, size_t),
+                  void *p_sni )
+{
+    conf->f_sni = f_sni;
+    conf->p_sni = p_sni;
+}
+#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
+
+#if defined(MBEDTLS_SSL_ALPN)
+int mbedtls_ssl_conf_alpn_protocols( mbedtls_ssl_config *conf, const char **protos )
+{
+    size_t cur_len, tot_len;
+    const char **p;
+
+    /*
+     * RFC 7301 3.1: "Empty strings MUST NOT be included and byte strings
+     * MUST NOT be truncated."
+     * We check lengths now rather than later.
+     */
+    tot_len = 0;
+    for( p = protos; *p != NULL; p++ )
+    {
+        cur_len = strlen( *p );
+        tot_len += cur_len;
+
+        if( cur_len == 0 || cur_len > 255 || tot_len > 65535 )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    conf->alpn_list = protos;
+
+    return( 0 );
+}
+
+const char *mbedtls_ssl_get_alpn_protocol( const mbedtls_ssl_context *ssl )
+{
+    return( ssl->alpn_chosen );
+}
+#endif /* MBEDTLS_SSL_ALPN */
+
+void mbedtls_ssl_conf_max_version( mbedtls_ssl_config *conf, int major, int minor )
+{
+    conf->max_major_ver = major;
+    conf->max_minor_ver = minor;
+}
+
+void mbedtls_ssl_conf_min_version( mbedtls_ssl_config *conf, int major, int minor )
+{
+    conf->min_major_ver = major;
+    conf->min_minor_ver = minor;
+}
+
+#if defined(MBEDTLS_SSL_FALLBACK_SCSV) && defined(MBEDTLS_SSL_CLI_C)
+void mbedtls_ssl_conf_fallback( mbedtls_ssl_config *conf, char fallback )
+{
+    conf->fallback = fallback;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_SRV_C)
+void mbedtls_ssl_conf_cert_req_ca_list( mbedtls_ssl_config *conf,
+                                          char cert_req_ca_list )
+{
+    conf->cert_req_ca_list = cert_req_ca_list;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+void mbedtls_ssl_conf_encrypt_then_mac( mbedtls_ssl_config *conf, char etm )
+{
+    conf->encrypt_then_mac = etm;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+void mbedtls_ssl_conf_extended_master_secret( mbedtls_ssl_config *conf, char ems )
+{
+    conf->extended_ms = ems;
+}
+#endif
+
+#if defined(MBEDTLS_ARC4_C)
+void mbedtls_ssl_conf_arc4_support( mbedtls_ssl_config *conf, char arc4 )
+{
+    conf->arc4_disabled = arc4;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+int mbedtls_ssl_conf_max_frag_len( mbedtls_ssl_config *conf, unsigned char mfl_code )
+{
+    if( mfl_code >= MBEDTLS_SSL_MAX_FRAG_LEN_INVALID ||
+        ssl_mfl_code_to_length( mfl_code ) > MBEDTLS_TLS_EXT_ADV_CONTENT_LEN )
+    {
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    conf->mfl_code = mfl_code;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+void mbedtls_ssl_conf_truncated_hmac( mbedtls_ssl_config *conf, int truncate )
+{
+    conf->trunc_hmac = truncate;
+}
+#endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
+
+#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
+void mbedtls_ssl_conf_cbc_record_splitting( mbedtls_ssl_config *conf, char split )
+{
+    conf->cbc_record_splitting = split;
+}
+#endif
+
+void mbedtls_ssl_conf_legacy_renegotiation( mbedtls_ssl_config *conf, int allow_legacy )
+{
+    conf->allow_legacy_renegotiation = allow_legacy;
+}
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+void mbedtls_ssl_conf_renegotiation( mbedtls_ssl_config *conf, int renegotiation )
+{
+    conf->disable_renegotiation = renegotiation;
+}
+
+void mbedtls_ssl_conf_renegotiation_enforced( mbedtls_ssl_config *conf, int max_records )
+{
+    conf->renego_max_records = max_records;
+}
+
+void mbedtls_ssl_conf_renegotiation_period( mbedtls_ssl_config *conf,
+                                   const unsigned char period[8] )
+{
+    memcpy( conf->renego_period, period, 8 );
+}
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+#if defined(MBEDTLS_SSL_CLI_C)
+void mbedtls_ssl_conf_session_tickets( mbedtls_ssl_config *conf, int use_tickets )
+{
+    conf->session_tickets = use_tickets;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_SRV_C)
+void mbedtls_ssl_conf_session_tickets_cb( mbedtls_ssl_config *conf,
+        mbedtls_ssl_ticket_write_t *f_ticket_write,
+        mbedtls_ssl_ticket_parse_t *f_ticket_parse,
+        void *p_ticket )
+{
+    conf->f_ticket_write = f_ticket_write;
+    conf->f_ticket_parse = f_ticket_parse;
+    conf->p_ticket       = p_ticket;
+}
+#endif
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+void mbedtls_ssl_conf_export_keys_cb( mbedtls_ssl_config *conf,
+        mbedtls_ssl_export_keys_t *f_export_keys,
+        void *p_export_keys )
+{
+    conf->f_export_keys = f_export_keys;
+    conf->p_export_keys = p_export_keys;
+}
+#endif
+
+#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
+void mbedtls_ssl_conf_async_private_cb(
+    mbedtls_ssl_config *conf,
+    mbedtls_ssl_async_sign_t *f_async_sign,
+    mbedtls_ssl_async_decrypt_t *f_async_decrypt,
+    mbedtls_ssl_async_resume_t *f_async_resume,
+    mbedtls_ssl_async_cancel_t *f_async_cancel,
+    void *async_config_data )
+{
+    conf->f_async_sign_start = f_async_sign;
+    conf->f_async_decrypt_start = f_async_decrypt;
+    conf->f_async_resume = f_async_resume;
+    conf->f_async_cancel = f_async_cancel;
+    conf->p_async_config_data = async_config_data;
+}
+
+void *mbedtls_ssl_conf_get_async_config_data( const mbedtls_ssl_config *conf )
+{
+    return( conf->p_async_config_data );
+}
+
+void *mbedtls_ssl_get_async_operation_data( const mbedtls_ssl_context *ssl )
+{
+    if( ssl->handshake == NULL )
+        return( NULL );
+    else
+        return( ssl->handshake->user_async_ctx );
+}
+
+void mbedtls_ssl_set_async_operation_data( mbedtls_ssl_context *ssl,
+                                 void *ctx )
+{
+    if( ssl->handshake != NULL )
+        ssl->handshake->user_async_ctx = ctx;
+}
+#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
+
+/*
+ * SSL get accessors
+ */
+size_t mbedtls_ssl_get_bytes_avail( const mbedtls_ssl_context *ssl )
+{
+    return( ssl->in_offt == NULL ? 0 : ssl->in_msglen );
+}
+
+int mbedtls_ssl_check_pending( const mbedtls_ssl_context *ssl )
+{
+    /*
+     * Case A: We're currently holding back
+     * a message for further processing.
+     */
+
+    if( ssl->keep_current_message == 1 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: record held back for processing" ) );
+        return( 1 );
+    }
+
+    /*
+     * Case B: Further records are pending in the current datagram.
+     */
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->in_left > ssl->next_record_offset )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more records within current datagram" ) );
+        return( 1 );
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    /*
+     * Case C: A handshake message is being processed.
+     */
+
+    if( ssl->in_hslen > 0 && ssl->in_hslen < ssl->in_msglen )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more handshake messages within current record" ) );
+        return( 1 );
+    }
+
+    /*
+     * Case D: An application data message is being processed
+     */
+    if( ssl->in_offt != NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: application data record is being processed" ) );
+        return( 1 );
+    }
+
+    /*
+     * In all other cases, the rest of the message can be dropped.
+     * As in ssl_get_next_record, this needs to be adapted if
+     * we implement support for multiple alerts in single records.
+     */
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: nothing pending" ) );
+    return( 0 );
+}
+
+uint32_t mbedtls_ssl_get_verify_result( const mbedtls_ssl_context *ssl )
+{
+    if( ssl->session != NULL )
+        return( ssl->session->verify_result );
+
+    if( ssl->session_negotiate != NULL )
+        return( ssl->session_negotiate->verify_result );
+
+    return( 0xFFFFFFFF );
+}
+
+const char *mbedtls_ssl_get_ciphersuite( const mbedtls_ssl_context *ssl )
+{
+    if( ssl == NULL || ssl->session == NULL )
+        return( NULL );
+
+    return mbedtls_ssl_get_ciphersuite_name( ssl->session->ciphersuite );
+}
+
+const char *mbedtls_ssl_get_version( const mbedtls_ssl_context *ssl )
+{
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        switch( ssl->minor_ver )
+        {
+            case MBEDTLS_SSL_MINOR_VERSION_2:
+                return( "DTLSv1.0" );
+
+            case MBEDTLS_SSL_MINOR_VERSION_3:
+                return( "DTLSv1.2" );
+
+            default:
+                return( "unknown (DTLS)" );
+        }
+    }
+#endif
+
+    switch( ssl->minor_ver )
+    {
+        case MBEDTLS_SSL_MINOR_VERSION_0:
+            return( "SSLv3.0" );
+
+        case MBEDTLS_SSL_MINOR_VERSION_1:
+            return( "TLSv1.0" );
+
+        case MBEDTLS_SSL_MINOR_VERSION_2:
+            return( "TLSv1.1" );
+
+        case MBEDTLS_SSL_MINOR_VERSION_3:
+            return( "TLSv1.2" );
+
+        default:
+            return( "unknown" );
+    }
+}
+
+int mbedtls_ssl_get_record_expansion( const mbedtls_ssl_context *ssl )
+{
+    size_t transform_expansion = 0;
+    const mbedtls_ssl_transform *transform = ssl->transform_out;
+    unsigned block_size;
+
+    if( transform == NULL )
+        return( (int) mbedtls_ssl_hdr_len( ssl ) );
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    if( ssl->session_out->compression != MBEDTLS_SSL_COMPRESS_NULL )
+        return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif
+
+    switch( mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_enc ) )
+    {
+        case MBEDTLS_MODE_GCM:
+        case MBEDTLS_MODE_CCM:
+        case MBEDTLS_MODE_CHACHAPOLY:
+        case MBEDTLS_MODE_STREAM:
+            transform_expansion = transform->minlen;
+            break;
+
+        case MBEDTLS_MODE_CBC:
+
+            block_size = mbedtls_cipher_get_block_size(
+                &transform->cipher_ctx_enc );
+
+            /* Expansion due to the addition of the MAC. */
+            transform_expansion += transform->maclen;
+
+            /* Expansion due to the addition of CBC padding;
+             * Theoretically up to 256 bytes, but we never use
+             * more than the block size of the underlying cipher. */
+            transform_expansion += block_size;
+
+            /* For TLS 1.1 or higher, an explicit IV is added
+             * after the record header. */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
+            if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
+                transform_expansion += block_size;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
+
+            break;
+
+        default:
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    return( (int)( mbedtls_ssl_hdr_len( ssl ) + transform_expansion ) );
+}
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl )
+{
+    size_t max_len;
+
+    /*
+     * Assume mfl_code is correct since it was checked when set
+     */
+    max_len = ssl_mfl_code_to_length( ssl->conf->mfl_code );
+
+    /* Check if a smaller max length was negotiated */
+    if( ssl->session_out != NULL &&
+        ssl_mfl_code_to_length( ssl->session_out->mfl_code ) < max_len )
+    {
+        max_len = ssl_mfl_code_to_length( ssl->session_out->mfl_code );
+    }
+
+    /* During a handshake, use the value being negotiated */
+    if( ssl->session_negotiate != NULL &&
+        ssl_mfl_code_to_length( ssl->session_negotiate->mfl_code ) < max_len )
+    {
+        max_len = ssl_mfl_code_to_length( ssl->session_negotiate->mfl_code );
+    }
+
+    return( max_len );
+}
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+static size_t ssl_get_current_mtu( const mbedtls_ssl_context *ssl )
+{
+    /* Return unlimited mtu for client hello messages to avoid fragmentation. */
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
+        ( ssl->state == MBEDTLS_SSL_CLIENT_HELLO ||
+          ssl->state == MBEDTLS_SSL_SERVER_HELLO ) )
+        return ( 0 );
+
+    if( ssl->handshake == NULL || ssl->handshake->mtu == 0 )
+        return( ssl->mtu );
+
+    if( ssl->mtu == 0 )
+        return( ssl->handshake->mtu );
+
+    return( ssl->mtu < ssl->handshake->mtu ?
+            ssl->mtu : ssl->handshake->mtu );
+}
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+int mbedtls_ssl_get_max_out_record_payload( const mbedtls_ssl_context *ssl )
+{
+    size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
+
+#if !defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) && \
+    !defined(MBEDTLS_SSL_PROTO_DTLS)
+    (void) ssl;
+#endif
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    const size_t mfl = mbedtls_ssl_get_max_frag_len( ssl );
+
+    if( max_len > mfl )
+        max_len = mfl;
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl_get_current_mtu( ssl ) != 0 )
+    {
+        const size_t mtu = ssl_get_current_mtu( ssl );
+        const int ret = mbedtls_ssl_get_record_expansion( ssl );
+        const size_t overhead = (size_t) ret;
+
+        if( ret < 0 )
+            return( ret );
+
+        if( mtu <= overhead )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "MTU too low for record expansion" ) );
+            return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+        }
+
+        if( max_len > mtu - overhead )
+            max_len = mtu - overhead;
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+#if !defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) &&        \
+    !defined(MBEDTLS_SSL_PROTO_DTLS)
+    ((void) ssl);
+#endif
+
+    return( (int) max_len );
+}
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+const mbedtls_x509_crt *mbedtls_ssl_get_peer_cert( const mbedtls_ssl_context *ssl )
+{
+    if( ssl == NULL || ssl->session == NULL )
+        return( NULL );
+
+#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    return( ssl->session->peer_cert );
+#else
+    return( NULL );
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+}
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+#if defined(MBEDTLS_SSL_CLI_C)
+int mbedtls_ssl_get_session( const mbedtls_ssl_context *ssl,
+                             mbedtls_ssl_session *dst )
+{
+    if( ssl == NULL ||
+        dst == NULL ||
+        ssl->session == NULL ||
+        ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT )
+    {
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    return( mbedtls_ssl_session_copy( dst, ssl->session ) );
+}
+#endif /* MBEDTLS_SSL_CLI_C */
+
+/*
+ * Perform a single step of the SSL handshake
+ */
+int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+
+    if( ssl == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_SSL_CLI_C)
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+        ret = mbedtls_ssl_handshake_client_step( ssl );
+#endif
+#if defined(MBEDTLS_SSL_SRV_C)
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+        ret = mbedtls_ssl_handshake_server_step( ssl );
+#endif
+
+    return( ret );
+}
+
+/*
+ * Perform the SSL handshake
+ */
+int mbedtls_ssl_handshake( mbedtls_ssl_context *ssl )
+{
+    int ret = 0;
+
+    if( ssl == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> handshake" ) );
+
+    while( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+    {
+        ret = mbedtls_ssl_handshake_step( ssl );
+
+        if( ret != 0 )
+            break;
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= handshake" ) );
+
+    return( ret );
+}
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+#if defined(MBEDTLS_SSL_SRV_C)
+/*
+ * Write HelloRequest to request renegotiation on server
+ */
+static int ssl_write_hello_request( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write hello request" ) );
+
+    ssl->out_msglen  = 4;
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
+    ssl->out_msg[0]  = MBEDTLS_SSL_HS_HELLO_REQUEST;
+
+    if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write hello request" ) );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_SRV_C */
+
+/*
+ * Actually renegotiate current connection, triggered by either:
+ * - any side: calling mbedtls_ssl_renegotiate(),
+ * - client: receiving a HelloRequest during mbedtls_ssl_read(),
+ * - server: receiving any handshake message on server during mbedtls_ssl_read() after
+ *   the initial handshake is completed.
+ * If the handshake doesn't complete due to waiting for I/O, it will continue
+ * during the next calls to mbedtls_ssl_renegotiate() or mbedtls_ssl_read() respectively.
+ */
+static int ssl_start_renegotiation( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> renegotiate" ) );
+
+    if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
+        return( ret );
+
+    /* RFC 6347 4.2.2: "[...] the HelloRequest will have message_seq = 0 and
+     * the ServerHello will have message_seq = 1" */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
+    {
+        if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+            ssl->handshake->out_msg_seq = 1;
+        else
+            ssl->handshake->in_msg_seq = 1;
+    }
+#endif
+
+    ssl->state = MBEDTLS_SSL_HELLO_REQUEST;
+    ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS;
+
+    if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= renegotiate" ) );
+
+    return( 0 );
+}
+
+/*
+ * Renegotiate current connection on client,
+ * or request renegotiation on server
+ */
+int mbedtls_ssl_renegotiate( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+
+    if( ssl == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_SSL_SRV_C)
+    /* On server, just send the request */
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+        ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING;
+
+        /* Did we already try/start sending HelloRequest? */
+        if( ssl->out_left != 0 )
+            return( mbedtls_ssl_flush_output( ssl ) );
+
+        return( ssl_write_hello_request( ssl ) );
+    }
+#endif /* MBEDTLS_SSL_SRV_C */
+
+#if defined(MBEDTLS_SSL_CLI_C)
+    /*
+     * On client, either start the renegotiation process or,
+     * if already in progress, continue the handshake
+     */
+    if( ssl->renego_status != MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
+    {
+        if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+        if( ( ret = ssl_start_renegotiation( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_start_renegotiation", ret );
+            return( ret );
+        }
+    }
+    else
+    {
+        if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
+            return( ret );
+        }
+    }
+#endif /* MBEDTLS_SSL_CLI_C */
+
+    return( ret );
+}
+
+/*
+ * Check record counters and renegotiate if they're above the limit.
+ */
+static int ssl_check_ctr_renegotiate( mbedtls_ssl_context *ssl )
+{
+    size_t ep_len = ssl_ep_len( ssl );
+    int in_ctr_cmp;
+    int out_ctr_cmp;
+
+    if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER ||
+        ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING ||
+        ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED )
+    {
+        return( 0 );
+    }
+
+    in_ctr_cmp = memcmp( ssl->in_ctr + ep_len,
+                        ssl->conf->renego_period + ep_len, 8 - ep_len );
+    out_ctr_cmp = memcmp( ssl->cur_out_ctr + ep_len,
+                          ssl->conf->renego_period + ep_len, 8 - ep_len );
+
+    if( in_ctr_cmp <= 0 && out_ctr_cmp <= 0 )
+    {
+        return( 0 );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "record counter limit reached: renegotiate" ) );
+    return( mbedtls_ssl_renegotiate( ssl ) );
+}
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+/*
+ * Receive application data decrypted from the SSL layer
+ */
+int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
+{
+    int ret;
+    size_t n;
+
+    if( ssl == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read" ) );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+            return( ret );
+
+        if( ssl->handshake != NULL &&
+            ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
+        {
+            if( ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
+                return( ret );
+        }
+    }
+#endif
+
+    /*
+     * Check if renegotiation is necessary and/or handshake is
+     * in process. If yes, perform/continue, and fall through
+     * if an unexpected packet is received while the client
+     * is waiting for the ServerHello.
+     *
+     * (There is no equivalent to the last condition on
+     *  the server-side as it is not treated as within
+     *  a handshake while waiting for the ClientHello
+     *  after a renegotiation request.)
+     */
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    ret = ssl_check_ctr_renegotiate( ssl );
+    if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
+        ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
+        return( ret );
+    }
+#endif
+
+    if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+    {
+        ret = mbedtls_ssl_handshake( ssl );
+        if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
+            ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
+            return( ret );
+        }
+    }
+
+    /* Loop as long as no application data record is available */
+    while( ssl->in_offt == NULL )
+    {
+        /* Start timer if not already running */
+        if( ssl->f_get_timer != NULL &&
+            ssl->f_get_timer( ssl->p_timer ) == -1 )
+        {
+            ssl_set_timer( ssl, ssl->conf->read_timeout );
+        }
+
+        if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+        {
+            if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
+                return( 0 );
+
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+            return( ret );
+        }
+
+        if( ssl->in_msglen  == 0 &&
+            ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA )
+        {
+            /*
+             * OpenSSL sends empty messages to randomize the IV
+             */
+            if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+            {
+                if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
+                    return( 0 );
+
+                MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+                return( ret );
+            }
+        }
+
+        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "received handshake message" ) );
+
+            /*
+             * - For client-side, expect SERVER_HELLO_REQUEST.
+             * - For server-side, expect CLIENT_HELLO.
+             * - Fail (TLS) or silently drop record (DTLS) in other cases.
+             */
+
+#if defined(MBEDTLS_SSL_CLI_C)
+            if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
+                ( ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_REQUEST ||
+                  ssl->in_hslen  != mbedtls_ssl_hs_hdr_len( ssl ) ) )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not HelloRequest)" ) );
+
+                /* With DTLS, drop the packet (probably from last handshake) */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+                if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+                {
+                    continue;
+                }
+#endif
+                return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+            }
+#endif /* MBEDTLS_SSL_CLI_C */
+
+#if defined(MBEDTLS_SSL_SRV_C)
+            if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
+                ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not ClientHello)" ) );
+
+                /* With DTLS, drop the packet (probably from last handshake) */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+                if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+                {
+                    continue;
+                }
+#endif
+                return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+            }
+#endif /* MBEDTLS_SSL_SRV_C */
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+            /* Determine whether renegotiation attempt should be accepted */
+            if( ! ( ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED ||
+                    ( ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
+                      ssl->conf->allow_legacy_renegotiation ==
+                                                   MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION ) ) )
+            {
+                /*
+                 * Accept renegotiation request
+                 */
+
+                /* DTLS clients need to know renego is server-initiated */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+                if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+                    ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
+                {
+                    ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING;
+                }
+#endif
+                ret = ssl_start_renegotiation( ssl );
+                if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
+                    ret != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_RET( 1, "ssl_start_renegotiation", ret );
+                    return( ret );
+                }
+            }
+            else
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+            {
+                /*
+                 * Refuse renegotiation
+                 */
+
+                MBEDTLS_SSL_DEBUG_MSG( 3, ( "refusing renegotiation, sending alert" ) );
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+                if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+                {
+                    /* SSLv3 does not have a "no_renegotiation" warning, so
+                       we send a fatal alert and abort the connection. */
+                    mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                                    MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+                    return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+                }
+                else
+#endif /* MBEDTLS_SSL_PROTO_SSL3 */
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+                if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
+                {
+                    if( ( ret = mbedtls_ssl_send_alert_message( ssl,
+                                    MBEDTLS_SSL_ALERT_LEVEL_WARNING,
+                                    MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION ) ) != 0 )
+                    {
+                        return( ret );
+                    }
+                }
+                else
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 ||
+          MBEDTLS_SSL_PROTO_TLS1_2 */
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+                    return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+                }
+            }
+
+            /* At this point, we don't know whether the renegotiation has been
+             * completed or not. The cases to consider are the following:
+             * 1) The renegotiation is complete. In this case, no new record
+             *    has been read yet.
+             * 2) The renegotiation is incomplete because the client received
+             *    an application data record while awaiting the ServerHello.
+             * 3) The renegotiation is incomplete because the client received
+             *    a non-handshake, non-application data message while awaiting
+             *    the ServerHello.
+             * In each of these case, looping will be the proper action:
+             * - For 1), the next iteration will read a new record and check
+             *   if it's application data.
+             * - For 2), the loop condition isn't satisfied as application data
+             *   is present, hence continue is the same as break
+             * - For 3), the loop condition is satisfied and read_record
+             *   will re-deliver the message that was held back by the client
+             *   when expecting the ServerHello.
+             */
+            continue;
+        }
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+        else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
+        {
+            if( ssl->conf->renego_max_records >= 0 )
+            {
+                if( ++ssl->renego_records_seen > ssl->conf->renego_max_records )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "renegotiation requested, "
+                                        "but not honored by client" ) );
+                    return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+                }
+            }
+        }
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+        /* Fatal and closure alerts handled by mbedtls_ssl_read_record() */
+        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "ignoring non-fatal non-closure alert" ) );
+            return( MBEDTLS_ERR_SSL_WANT_READ );
+        }
+
+        if( ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad application data message" ) );
+            return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+        }
+
+        ssl->in_offt = ssl->in_msg;
+
+        /* We're going to return something now, cancel timer,
+         * except if handshake (renegotiation) is in progress */
+        if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
+            ssl_set_timer( ssl, 0 );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        /* If we requested renego but received AppData, resend HelloRequest.
+         * Do it now, after setting in_offt, to avoid taking this branch
+         * again if ssl_write_hello_request() returns WANT_WRITE */
+#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
+        if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
+            ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
+        {
+            if( ( ret = ssl_resend_hello_request( ssl ) ) != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_RET( 1, "ssl_resend_hello_request", ret );
+                return( ret );
+            }
+        }
+#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+    }
+
+    n = ( len < ssl->in_msglen )
+        ? len : ssl->in_msglen;
+
+    memcpy( buf, ssl->in_offt, n );
+    ssl->in_msglen -= n;
+
+    if( ssl->in_msglen == 0 )
+    {
+        /* all bytes consumed */
+        ssl->in_offt = NULL;
+        ssl->keep_current_message = 0;
+    }
+    else
+    {
+        /* more data available */
+        ssl->in_offt += n;
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read" ) );
+
+    return( (int) n );
+}
+
+/*
+ * Send application data to be encrypted by the SSL layer, taking care of max
+ * fragment length and buffer size.
+ *
+ * According to RFC 5246 Section 6.2.1:
+ *
+ *      Zero-length fragments of Application data MAY be sent as they are
+ *      potentially useful as a traffic analysis countermeasure.
+ *
+ * Therefore, it is possible that the input message length is 0 and the
+ * corresponding return code is 0 on success.
+ */
+static int ssl_write_real( mbedtls_ssl_context *ssl,
+                           const unsigned char *buf, size_t len )
+{
+    int ret = mbedtls_ssl_get_max_out_record_payload( ssl );
+    const size_t max_len = (size_t) ret;
+
+    if( ret < 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_get_max_out_record_payload", ret );
+        return( ret );
+    }
+
+    if( len > max_len )
+    {
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "fragment larger than the (negotiated) "
+                                "maximum fragment length: %d > %d",
+                                len, max_len ) );
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+        }
+        else
+#endif
+            len = max_len;
+    }
+
+    if( ssl->out_left != 0 )
+    {
+        /*
+         * The user has previously tried to send the data and
+         * MBEDTLS_ERR_SSL_WANT_WRITE or the message was only partially
+         * written. In this case, we expect the high-level write function
+         * (e.g. mbedtls_ssl_write()) to be called with the same parameters
+         */
+        if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
+            return( ret );
+        }
+    }
+    else
+    {
+        /*
+         * The user is trying to send a message the first time, so we need to
+         * copy the data into the internal buffers and setup the data structure
+         * to keep track of partial writes
+         */
+        ssl->out_msglen  = len;
+        ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA;
+        memcpy( ssl->out_msg, buf, len );
+
+        if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
+            return( ret );
+        }
+    }
+
+    return( (int) len );
+}
+
+/*
+ * Write application data, doing 1/n-1 splitting if necessary.
+ *
+ * With non-blocking I/O, ssl_write_real() may return WANT_WRITE,
+ * then the caller will call us again with the same arguments, so
+ * remember whether we already did the split or not.
+ */
+#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
+static int ssl_write_split( mbedtls_ssl_context *ssl,
+                            const unsigned char *buf, size_t len )
+{
+    int ret;
+
+    if( ssl->conf->cbc_record_splitting ==
+            MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED ||
+        len <= 1 ||
+        ssl->minor_ver > MBEDTLS_SSL_MINOR_VERSION_1 ||
+        mbedtls_cipher_get_cipher_mode( &ssl->transform_out->cipher_ctx_enc )
+                                != MBEDTLS_MODE_CBC )
+    {
+        return( ssl_write_real( ssl, buf, len ) );
+    }
+
+    if( ssl->split_done == 0 )
+    {
+        if( ( ret = ssl_write_real( ssl, buf, 1 ) ) <= 0 )
+            return( ret );
+        ssl->split_done = 1;
+    }
+
+    if( ( ret = ssl_write_real( ssl, buf + 1, len - 1 ) ) <= 0 )
+        return( ret );
+    ssl->split_done = 0;
+
+    return( ret + 1 );
+}
+#endif /* MBEDTLS_SSL_CBC_RECORD_SPLITTING */
+
+/*
+ * Write application data (public-facing wrapper)
+ */
+int mbedtls_ssl_write( mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len )
+{
+    int ret;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write" ) );
+
+    if( ssl == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if( ( ret = ssl_check_ctr_renegotiate( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
+        return( ret );
+    }
+#endif
+
+    if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+    {
+        if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
+            return( ret );
+        }
+    }
+
+#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
+    ret = ssl_write_split( ssl, buf, len );
+#else
+    ret = ssl_write_real( ssl, buf, len );
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write" ) );
+
+    return( ret );
+}
+
+/*
+ * Notify the peer that the connection is being closed
+ */
+int mbedtls_ssl_close_notify( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    if( ssl == NULL || ssl->conf == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write close notify" ) );
+
+    if( ssl->out_left != 0 )
+        return( mbedtls_ssl_flush_output( ssl ) );
+
+    if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
+    {
+        if( ( ret = mbedtls_ssl_send_alert_message( ssl,
+                        MBEDTLS_SSL_ALERT_LEVEL_WARNING,
+                        MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_send_alert_message", ret );
+            return( ret );
+        }
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write close notify" ) );
+
+    return( 0 );
+}
+
+void mbedtls_ssl_transform_free( mbedtls_ssl_transform *transform )
+{
+    if( transform == NULL )
+        return;
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    deflateEnd( &transform->ctx_deflate );
+    inflateEnd( &transform->ctx_inflate );
+#endif
+
+    mbedtls_cipher_free( &transform->cipher_ctx_enc );
+    mbedtls_cipher_free( &transform->cipher_ctx_dec );
+
+    mbedtls_md_free( &transform->md_ctx_enc );
+    mbedtls_md_free( &transform->md_ctx_dec );
+
+    mbedtls_platform_zeroize( transform, sizeof( mbedtls_ssl_transform ) );
+}
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+static void ssl_key_cert_free( mbedtls_ssl_key_cert *key_cert )
+{
+    mbedtls_ssl_key_cert *cur = key_cert, *next;
+
+    while( cur != NULL )
+    {
+        next = cur->next;
+        mbedtls_free( cur );
+        cur = next;
+    }
+}
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+
+static void ssl_buffering_free( mbedtls_ssl_context *ssl )
+{
+    unsigned offset;
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+
+    if( hs == NULL )
+        return;
+
+    ssl_free_buffered_record( ssl );
+
+    for( offset = 0; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++ )
+        ssl_buffering_free_slot( ssl, offset );
+}
+
+static void ssl_buffering_free_slot( mbedtls_ssl_context *ssl,
+                                     uint8_t slot )
+{
+    mbedtls_ssl_handshake_params * const hs = ssl->handshake;
+    mbedtls_ssl_hs_buffer * const hs_buf = &hs->buffering.hs[slot];
+
+    if( slot >= MBEDTLS_SSL_MAX_BUFFERED_HS )
+        return;
+
+    if( hs_buf->is_valid == 1 )
+    {
+        hs->buffering.total_bytes_buffered -= hs_buf->data_len;
+        mbedtls_platform_zeroize( hs_buf->data, hs_buf->data_len );
+        mbedtls_free( hs_buf->data );
+        memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
+    }
+}
+
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
+{
+    mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+
+    if( handshake == NULL )
+        return;
+
+#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
+    if( ssl->conf->f_async_cancel != NULL && handshake->async_in_progress != 0 )
+    {
+        ssl->conf->f_async_cancel( ssl );
+        handshake->async_in_progress = 0;
+    }
+#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+    mbedtls_md5_free(    &handshake->fin_md5  );
+    mbedtls_sha1_free(   &handshake->fin_sha1 );
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_SHA256_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_abort( &handshake->fin_sha256_psa );
+#else
+    mbedtls_sha256_free(   &handshake->fin_sha256    );
+#endif
+#endif
+#if defined(MBEDTLS_SHA512_C)
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_hash_abort( &handshake->fin_sha384_psa );
+#else
+    mbedtls_sha512_free(   &handshake->fin_sha512    );
+#endif
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#if defined(MBEDTLS_DHM_C)
+    mbedtls_dhm_free( &handshake->dhm_ctx );
+#endif
+#if defined(MBEDTLS_ECDH_C)
+    mbedtls_ecdh_free( &handshake->ecdh_ctx );
+#endif
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    mbedtls_ecjpake_free( &handshake->ecjpake_ctx );
+#if defined(MBEDTLS_SSL_CLI_C)
+    mbedtls_free( handshake->ecjpake_cache );
+    handshake->ecjpake_cache = NULL;
+    handshake->ecjpake_cache_len = 0;
+#endif
+#endif
+
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    /* explicit void pointer cast for buggy MS compiler */
+    mbedtls_free( (void *) handshake->curves );
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
+    if( handshake->psk != NULL )
+    {
+        mbedtls_platform_zeroize( handshake->psk, handshake->psk_len );
+        mbedtls_free( handshake->psk );
+    }
+#endif
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
+    defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+    /*
+     * Free only the linked list wrapper, not the keys themselves
+     * since the belong to the SNI callback
+     */
+    if( handshake->sni_key_cert != NULL )
+    {
+        mbedtls_ssl_key_cert *cur = handshake->sni_key_cert, *next;
+
+        while( cur != NULL )
+        {
+            next = cur->next;
+            mbedtls_free( cur );
+            cur = next;
+        }
+    }
+#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_SERVER_NAME_INDICATION */
+
+#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
+    mbedtls_x509_crt_restart_free( &handshake->ecrs_ctx );
+    if( handshake->ecrs_peer_cert != NULL )
+    {
+        mbedtls_x509_crt_free( handshake->ecrs_peer_cert );
+        mbedtls_free( handshake->ecrs_peer_cert );
+    }
+#endif
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C) &&        \
+    !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    mbedtls_pk_free( &handshake->peer_pubkey );
+#endif /* MBEDTLS_X509_CRT_PARSE_C && !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    mbedtls_free( handshake->verify_cookie );
+    ssl_flight_free( handshake->flight );
+    ssl_buffering_free( ssl );
+#endif
+
+#if defined(MBEDTLS_ECDH_C) &&                  \
+    defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_destroy_key( handshake->ecdh_psa_privkey );
+#endif /* MBEDTLS_ECDH_C && MBEDTLS_USE_PSA_CRYPTO */
+
+    mbedtls_platform_zeroize( handshake,
+                              sizeof( mbedtls_ssl_handshake_params ) );
+}
+
+void mbedtls_ssl_session_free( mbedtls_ssl_session *session )
+{
+    if( session == NULL )
+        return;
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+    ssl_clear_peer_cert( session );
+#endif
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
+    mbedtls_free( session->ticket );
+#endif
+
+    mbedtls_platform_zeroize( session, sizeof( mbedtls_ssl_session ) );
+}
+
+/*
+ * Free an SSL context
+ */
+void mbedtls_ssl_free( mbedtls_ssl_context *ssl )
+{
+    if( ssl == NULL )
+        return;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> free" ) );
+
+    if( ssl->out_buf != NULL )
+    {
+        mbedtls_platform_zeroize( ssl->out_buf, MBEDTLS_SSL_OUT_BUFFER_LEN );
+        mbedtls_free( ssl->out_buf );
+    }
+
+    if( ssl->in_buf != NULL )
+    {
+        mbedtls_platform_zeroize( ssl->in_buf, MBEDTLS_SSL_IN_BUFFER_LEN );
+        mbedtls_free( ssl->in_buf );
+    }
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    if( ssl->compress_buf != NULL )
+    {
+        mbedtls_platform_zeroize( ssl->compress_buf, MBEDTLS_SSL_COMPRESS_BUFFER_LEN );
+        mbedtls_free( ssl->compress_buf );
+    }
+#endif
+
+    if( ssl->transform )
+    {
+        mbedtls_ssl_transform_free( ssl->transform );
+        mbedtls_free( ssl->transform );
+    }
+
+    if( ssl->handshake )
+    {
+        mbedtls_ssl_handshake_free( ssl );
+        mbedtls_ssl_transform_free( ssl->transform_negotiate );
+        mbedtls_ssl_session_free( ssl->session_negotiate );
+
+        mbedtls_free( ssl->handshake );
+        mbedtls_free( ssl->transform_negotiate );
+        mbedtls_free( ssl->session_negotiate );
+    }
+
+    if( ssl->session )
+    {
+        mbedtls_ssl_session_free( ssl->session );
+        mbedtls_free( ssl->session );
+    }
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+    if( ssl->hostname != NULL )
+    {
+        mbedtls_platform_zeroize( ssl->hostname, strlen( ssl->hostname ) );
+        mbedtls_free( ssl->hostname );
+    }
+#endif
+
+#if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
+    if( mbedtls_ssl_hw_record_finish != NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_finish()" ) );
+        mbedtls_ssl_hw_record_finish( ssl );
+    }
+#endif
+
+#if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
+    mbedtls_free( ssl->cli_id );
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= free" ) );
+
+    /* Actually clear after last debug message */
+    mbedtls_platform_zeroize( ssl, sizeof( mbedtls_ssl_context ) );
+}
+
+/*
+ * Initialze mbedtls_ssl_config
+ */
+void mbedtls_ssl_config_init( mbedtls_ssl_config *conf )
+{
+    memset( conf, 0, sizeof( mbedtls_ssl_config ) );
+}
+
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+static int ssl_preset_default_hashes[] = {
+#if defined(MBEDTLS_SHA512_C)
+    MBEDTLS_MD_SHA512,
+    MBEDTLS_MD_SHA384,
+#endif
+#if defined(MBEDTLS_SHA256_C)
+    MBEDTLS_MD_SHA256,
+    MBEDTLS_MD_SHA224,
+#endif
+#if defined(MBEDTLS_SHA1_C) && defined(MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE)
+    MBEDTLS_MD_SHA1,
+#endif
+    MBEDTLS_MD_NONE
+};
+#endif
+
+static int ssl_preset_suiteb_ciphersuites[] = {
+    MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+    MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+    0
+};
+
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+static int ssl_preset_suiteb_hashes[] = {
+    MBEDTLS_MD_SHA256,
+    MBEDTLS_MD_SHA384,
+    MBEDTLS_MD_NONE
+};
+#endif
+
+#if defined(MBEDTLS_ECP_C)
+static mbedtls_ecp_group_id ssl_preset_suiteb_curves[] = {
+    MBEDTLS_ECP_DP_SECP256R1,
+    MBEDTLS_ECP_DP_SECP384R1,
+    MBEDTLS_ECP_DP_NONE
+};
+#endif
+
+/*
+ * Load default in mbedtls_ssl_config
+ */
+int mbedtls_ssl_config_defaults( mbedtls_ssl_config *conf,
+                                 int endpoint, int transport, int preset )
+{
+#if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
+    int ret;
+#endif
+
+    /* Use the functions here so that they are covered in tests,
+     * but otherwise access member directly for efficiency */
+    mbedtls_ssl_conf_endpoint( conf, endpoint );
+    mbedtls_ssl_conf_transport( conf, transport );
+
+    /*
+     * Things that are common to all presets
+     */
+#if defined(MBEDTLS_SSL_CLI_C)
+    if( endpoint == MBEDTLS_SSL_IS_CLIENT )
+    {
+        conf->authmode = MBEDTLS_SSL_VERIFY_REQUIRED;
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+        conf->session_tickets = MBEDTLS_SSL_SESSION_TICKETS_ENABLED;
+#endif
+    }
+#endif
+
+#if defined(MBEDTLS_ARC4_C)
+    conf->arc4_disabled = MBEDTLS_SSL_ARC4_DISABLED;
+#endif
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+    conf->encrypt_then_mac = MBEDTLS_SSL_ETM_ENABLED;
+#endif
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+    conf->extended_ms = MBEDTLS_SSL_EXTENDED_MS_ENABLED;
+#endif
+
+#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
+    conf->cbc_record_splitting = MBEDTLS_SSL_CBC_RECORD_SPLITTING_ENABLED;
+#endif
+
+#if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
+    conf->f_cookie_write = ssl_cookie_write_dummy;
+    conf->f_cookie_check = ssl_cookie_check_dummy;
+#endif
+
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+    conf->anti_replay = MBEDTLS_SSL_ANTI_REPLAY_ENABLED;
+#endif
+
+#if defined(MBEDTLS_SSL_SRV_C)
+    conf->cert_req_ca_list = MBEDTLS_SSL_CERT_REQ_CA_LIST_ENABLED;
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    conf->hs_timeout_min = MBEDTLS_SSL_DTLS_TIMEOUT_DFL_MIN;
+    conf->hs_timeout_max = MBEDTLS_SSL_DTLS_TIMEOUT_DFL_MAX;
+#endif
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    conf->renego_max_records = MBEDTLS_SSL_RENEGO_MAX_RECORDS_DEFAULT;
+    memset( conf->renego_period,     0x00, 2 );
+    memset( conf->renego_period + 2, 0xFF, 6 );
+#endif
+
+#if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
+            if( endpoint == MBEDTLS_SSL_IS_SERVER )
+            {
+                const unsigned char dhm_p[] =
+                    MBEDTLS_DHM_RFC3526_MODP_2048_P_BIN;
+                const unsigned char dhm_g[] =
+                    MBEDTLS_DHM_RFC3526_MODP_2048_G_BIN;
+
+                if ( ( ret = mbedtls_ssl_conf_dh_param_bin( conf,
+                                               dhm_p, sizeof( dhm_p ),
+                                               dhm_g, sizeof( dhm_g ) ) ) != 0 )
+                {
+                    return( ret );
+                }
+            }
+#endif
+
+    /*
+     * Preset-specific defaults
+     */
+    switch( preset )
+    {
+        /*
+         * NSA Suite B
+         */
+        case MBEDTLS_SSL_PRESET_SUITEB:
+            conf->min_major_ver = MBEDTLS_SSL_MAJOR_VERSION_3;
+            conf->min_minor_ver = MBEDTLS_SSL_MINOR_VERSION_3; /* TLS 1.2 */
+            conf->max_major_ver = MBEDTLS_SSL_MAX_MAJOR_VERSION;
+            conf->max_minor_ver = MBEDTLS_SSL_MAX_MINOR_VERSION;
+
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_0] =
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_1] =
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_2] =
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_3] =
+                                   ssl_preset_suiteb_ciphersuites;
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+            conf->cert_profile = &mbedtls_x509_crt_profile_suiteb;
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+            conf->sig_hashes = ssl_preset_suiteb_hashes;
+#endif
+
+#if defined(MBEDTLS_ECP_C)
+            conf->curve_list = ssl_preset_suiteb_curves;
+#endif
+            break;
+
+        /*
+         * Default
+         */
+        default:
+            conf->min_major_ver = ( MBEDTLS_SSL_MIN_MAJOR_VERSION >
+                                    MBEDTLS_SSL_MIN_VALID_MAJOR_VERSION ) ?
+                                    MBEDTLS_SSL_MIN_MAJOR_VERSION :
+                                    MBEDTLS_SSL_MIN_VALID_MAJOR_VERSION;
+            conf->min_minor_ver = ( MBEDTLS_SSL_MIN_MINOR_VERSION >
+                                    MBEDTLS_SSL_MIN_VALID_MINOR_VERSION ) ?
+                                    MBEDTLS_SSL_MIN_MINOR_VERSION :
+                                    MBEDTLS_SSL_MIN_VALID_MINOR_VERSION;
+            conf->max_major_ver = MBEDTLS_SSL_MAX_MAJOR_VERSION;
+            conf->max_minor_ver = MBEDTLS_SSL_MAX_MINOR_VERSION;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+            if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+                conf->min_minor_ver = MBEDTLS_SSL_MINOR_VERSION_2;
+#endif
+
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_0] =
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_1] =
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_2] =
+            conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_3] =
+                                   mbedtls_ssl_list_ciphersuites();
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+            conf->cert_profile = &mbedtls_x509_crt_profile_default;
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+            conf->sig_hashes = ssl_preset_default_hashes;
+#endif
+
+#if defined(MBEDTLS_ECP_C)
+            conf->curve_list = mbedtls_ecp_grp_id_list();
+#endif
+
+#if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
+            conf->dhm_min_bitlen = 1024;
+#endif
+    }
+
+    return( 0 );
+}
+
+/*
+ * Free mbedtls_ssl_config
+ */
+void mbedtls_ssl_config_free( mbedtls_ssl_config *conf )
+{
+#if defined(MBEDTLS_DHM_C)
+    mbedtls_mpi_free( &conf->dhm_P );
+    mbedtls_mpi_free( &conf->dhm_G );
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
+    if( conf->psk != NULL )
+    {
+        mbedtls_platform_zeroize( conf->psk, conf->psk_len );
+        mbedtls_free( conf->psk );
+        conf->psk = NULL;
+        conf->psk_len = 0;
+    }
+
+    if( conf->psk_identity != NULL )
+    {
+        mbedtls_platform_zeroize( conf->psk_identity, conf->psk_identity_len );
+        mbedtls_free( conf->psk_identity );
+        conf->psk_identity = NULL;
+        conf->psk_identity_len = 0;
+    }
+#endif
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+    ssl_key_cert_free( conf->key_cert );
+#endif
+
+    mbedtls_platform_zeroize( conf, sizeof( mbedtls_ssl_config ) );
+}
+
+#if defined(MBEDTLS_PK_C) && \
+    ( defined(MBEDTLS_RSA_C) || defined(MBEDTLS_ECDSA_C) )
+/*
+ * Convert between MBEDTLS_PK_XXX and SSL_SIG_XXX
+ */
+unsigned char mbedtls_ssl_sig_from_pk( mbedtls_pk_context *pk )
+{
+#if defined(MBEDTLS_RSA_C)
+    if( mbedtls_pk_can_do( pk, MBEDTLS_PK_RSA ) )
+        return( MBEDTLS_SSL_SIG_RSA );
+#endif
+#if defined(MBEDTLS_ECDSA_C)
+    if( mbedtls_pk_can_do( pk, MBEDTLS_PK_ECDSA ) )
+        return( MBEDTLS_SSL_SIG_ECDSA );
+#endif
+    return( MBEDTLS_SSL_SIG_ANON );
+}
+
+unsigned char mbedtls_ssl_sig_from_pk_alg( mbedtls_pk_type_t type )
+{
+    switch( type ) {
+        case MBEDTLS_PK_RSA:
+            return( MBEDTLS_SSL_SIG_RSA );
+        case MBEDTLS_PK_ECDSA:
+        case MBEDTLS_PK_ECKEY:
+            return( MBEDTLS_SSL_SIG_ECDSA );
+        default:
+            return( MBEDTLS_SSL_SIG_ANON );
+    }
+}
+
+mbedtls_pk_type_t mbedtls_ssl_pk_alg_from_sig( unsigned char sig )
+{
+    switch( sig )
+    {
+#if defined(MBEDTLS_RSA_C)
+        case MBEDTLS_SSL_SIG_RSA:
+            return( MBEDTLS_PK_RSA );
+#endif
+#if defined(MBEDTLS_ECDSA_C)
+        case MBEDTLS_SSL_SIG_ECDSA:
+            return( MBEDTLS_PK_ECDSA );
+#endif
+        default:
+            return( MBEDTLS_PK_NONE );
+    }
+}
+#endif /* MBEDTLS_PK_C && ( MBEDTLS_RSA_C || MBEDTLS_ECDSA_C ) */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
+    defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+
+/* Find an entry in a signature-hash set matching a given hash algorithm. */
+mbedtls_md_type_t mbedtls_ssl_sig_hash_set_find( mbedtls_ssl_sig_hash_set_t *set,
+                                                 mbedtls_pk_type_t sig_alg )
+{
+    switch( sig_alg )
+    {
+        case MBEDTLS_PK_RSA:
+            return( set->rsa );
+        case MBEDTLS_PK_ECDSA:
+            return( set->ecdsa );
+        default:
+            return( MBEDTLS_MD_NONE );
+    }
+}
+
+/* Add a signature-hash-pair to a signature-hash set */
+void mbedtls_ssl_sig_hash_set_add( mbedtls_ssl_sig_hash_set_t *set,
+                                   mbedtls_pk_type_t sig_alg,
+                                   mbedtls_md_type_t md_alg )
+{
+    switch( sig_alg )
+    {
+        case MBEDTLS_PK_RSA:
+            if( set->rsa == MBEDTLS_MD_NONE )
+                set->rsa = md_alg;
+            break;
+
+        case MBEDTLS_PK_ECDSA:
+            if( set->ecdsa == MBEDTLS_MD_NONE )
+                set->ecdsa = md_alg;
+            break;
+
+        default:
+            break;
+    }
+}
+
+/* Allow exactly one hash algorithm for each signature. */
+void mbedtls_ssl_sig_hash_set_const_hash( mbedtls_ssl_sig_hash_set_t *set,
+                                          mbedtls_md_type_t md_alg )
+{
+    set->rsa   = md_alg;
+    set->ecdsa = md_alg;
+}
+
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2) &&
+          MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
+
+/*
+ * Convert from MBEDTLS_SSL_HASH_XXX to MBEDTLS_MD_XXX
+ */
+mbedtls_md_type_t mbedtls_ssl_md_alg_from_hash( unsigned char hash )
+{
+    switch( hash )
+    {
+#if defined(MBEDTLS_MD5_C)
+        case MBEDTLS_SSL_HASH_MD5:
+            return( MBEDTLS_MD_MD5 );
+#endif
+#if defined(MBEDTLS_SHA1_C)
+        case MBEDTLS_SSL_HASH_SHA1:
+            return( MBEDTLS_MD_SHA1 );
+#endif
+#if defined(MBEDTLS_SHA256_C)
+        case MBEDTLS_SSL_HASH_SHA224:
+            return( MBEDTLS_MD_SHA224 );
+        case MBEDTLS_SSL_HASH_SHA256:
+            return( MBEDTLS_MD_SHA256 );
+#endif
+#if defined(MBEDTLS_SHA512_C)
+        case MBEDTLS_SSL_HASH_SHA384:
+            return( MBEDTLS_MD_SHA384 );
+        case MBEDTLS_SSL_HASH_SHA512:
+            return( MBEDTLS_MD_SHA512 );
+#endif
+        default:
+            return( MBEDTLS_MD_NONE );
+    }
+}
+
+/*
+ * Convert from MBEDTLS_MD_XXX to MBEDTLS_SSL_HASH_XXX
+ */
+unsigned char mbedtls_ssl_hash_from_md_alg( int md )
+{
+    switch( md )
+    {
+#if defined(MBEDTLS_MD5_C)
+        case MBEDTLS_MD_MD5:
+            return( MBEDTLS_SSL_HASH_MD5 );
+#endif
+#if defined(MBEDTLS_SHA1_C)
+        case MBEDTLS_MD_SHA1:
+            return( MBEDTLS_SSL_HASH_SHA1 );
+#endif
+#if defined(MBEDTLS_SHA256_C)
+        case MBEDTLS_MD_SHA224:
+            return( MBEDTLS_SSL_HASH_SHA224 );
+        case MBEDTLS_MD_SHA256:
+            return( MBEDTLS_SSL_HASH_SHA256 );
+#endif
+#if defined(MBEDTLS_SHA512_C)
+        case MBEDTLS_MD_SHA384:
+            return( MBEDTLS_SSL_HASH_SHA384 );
+        case MBEDTLS_MD_SHA512:
+            return( MBEDTLS_SSL_HASH_SHA512 );
+#endif
+        default:
+            return( MBEDTLS_SSL_HASH_NONE );
+    }
+}
+
+#if defined(MBEDTLS_ECP_C)
+/*
+ * Check if a curve proposed by the peer is in our list.
+ * Return 0 if we're willing to use it, -1 otherwise.
+ */
+int mbedtls_ssl_check_curve( const mbedtls_ssl_context *ssl, mbedtls_ecp_group_id grp_id )
+{
+    const mbedtls_ecp_group_id *gid;
+
+    if( ssl->conf->curve_list == NULL )
+        return( -1 );
+
+    for( gid = ssl->conf->curve_list; *gid != MBEDTLS_ECP_DP_NONE; gid++ )
+        if( *gid == grp_id )
+            return( 0 );
+
+    return( -1 );
+}
+#endif /* MBEDTLS_ECP_C */
+
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
+/*
+ * Check if a hash proposed by the peer is in our list.
+ * Return 0 if we're willing to use it, -1 otherwise.
+ */
+int mbedtls_ssl_check_sig_hash( const mbedtls_ssl_context *ssl,
+                                mbedtls_md_type_t md )
+{
+    const int *cur;
+
+    if( ssl->conf->sig_hashes == NULL )
+        return( -1 );
+
+    for( cur = ssl->conf->sig_hashes; *cur != MBEDTLS_MD_NONE; cur++ )
+        if( *cur == (int) md )
+            return( 0 );
+
+    return( -1 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+int mbedtls_ssl_check_cert_usage( const mbedtls_x509_crt *cert,
+                          const mbedtls_ssl_ciphersuite_t *ciphersuite,
+                          int cert_endpoint,
+                          uint32_t *flags )
+{
+    int ret = 0;
+#if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
+    int usage = 0;
+#endif
+#if defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
+    const char *ext_oid;
+    size_t ext_len;
+#endif
+
+#if !defined(MBEDTLS_X509_CHECK_KEY_USAGE) &&          \
+    !defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
+    ((void) cert);
+    ((void) cert_endpoint);
+    ((void) flags);
+#endif
+
+#if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
+    if( cert_endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        /* Server part of the key exchange */
+        switch( ciphersuite->key_exchange )
+        {
+            case MBEDTLS_KEY_EXCHANGE_RSA:
+            case MBEDTLS_KEY_EXCHANGE_RSA_PSK:
+                usage = MBEDTLS_X509_KU_KEY_ENCIPHERMENT;
+                break;
+
+            case MBEDTLS_KEY_EXCHANGE_DHE_RSA:
+            case MBEDTLS_KEY_EXCHANGE_ECDHE_RSA:
+            case MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA:
+                usage = MBEDTLS_X509_KU_DIGITAL_SIGNATURE;
+                break;
+
+            case MBEDTLS_KEY_EXCHANGE_ECDH_RSA:
+            case MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA:
+                usage = MBEDTLS_X509_KU_KEY_AGREEMENT;
+                break;
+
+            /* Don't use default: we want warnings when adding new values */
+            case MBEDTLS_KEY_EXCHANGE_NONE:
+            case MBEDTLS_KEY_EXCHANGE_PSK:
+            case MBEDTLS_KEY_EXCHANGE_DHE_PSK:
+            case MBEDTLS_KEY_EXCHANGE_ECDHE_PSK:
+            case MBEDTLS_KEY_EXCHANGE_ECJPAKE:
+                usage = 0;
+        }
+    }
+    else
+    {
+        /* Client auth: we only implement rsa_sign and mbedtls_ecdsa_sign for now */
+        usage = MBEDTLS_X509_KU_DIGITAL_SIGNATURE;
+    }
+
+    if( mbedtls_x509_crt_check_key_usage( cert, usage ) != 0 )
+    {
+        *flags |= MBEDTLS_X509_BADCERT_KEY_USAGE;
+        ret = -1;
+    }
+#else
+    ((void) ciphersuite);
+#endif /* MBEDTLS_X509_CHECK_KEY_USAGE */
+
+#if defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
+    if( cert_endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        ext_oid = MBEDTLS_OID_SERVER_AUTH;
+        ext_len = MBEDTLS_OID_SIZE( MBEDTLS_OID_SERVER_AUTH );
+    }
+    else
+    {
+        ext_oid = MBEDTLS_OID_CLIENT_AUTH;
+        ext_len = MBEDTLS_OID_SIZE( MBEDTLS_OID_CLIENT_AUTH );
+    }
+
+    if( mbedtls_x509_crt_check_extended_key_usage( cert, ext_oid, ext_len ) != 0 )
+    {
+        *flags |= MBEDTLS_X509_BADCERT_EXT_KEY_USAGE;
+        ret = -1;
+    }
+#endif /* MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE */
+
+    return( ret );
+}
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
+/*
+ * Convert version numbers to/from wire format
+ * and, for DTLS, to/from TLS equivalent.
+ *
+ * For TLS this is the identity.
+ * For DTLS, use 1's complement (v -> 255 - v, and then map as follows:
+ * 1.0 <-> 3.2      (DTLS 1.0 is based on TLS 1.1)
+ * 1.x <-> 3.x+1    for x != 0 (DTLS 1.2 based on TLS 1.2)
+ */
+void mbedtls_ssl_write_version( int major, int minor, int transport,
+                        unsigned char ver[2] )
+{
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        if( minor == MBEDTLS_SSL_MINOR_VERSION_2 )
+            --minor; /* DTLS 1.0 stored as TLS 1.1 internally */
+
+        ver[0] = (unsigned char)( 255 - ( major - 2 ) );
+        ver[1] = (unsigned char)( 255 - ( minor - 1 ) );
+    }
+    else
+#else
+    ((void) transport);
+#endif
+    {
+        ver[0] = (unsigned char) major;
+        ver[1] = (unsigned char) minor;
+    }
+}
+
+void mbedtls_ssl_read_version( int *major, int *minor, int transport,
+                       const unsigned char ver[2] )
+{
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        *major = 255 - ver[0] + 2;
+        *minor = 255 - ver[1] + 1;
+
+        if( *minor == MBEDTLS_SSL_MINOR_VERSION_1 )
+            ++*minor; /* DTLS 1.0 stored as TLS 1.1 internally */
+    }
+    else
+#else
+    ((void) transport);
+#endif
+    {
+        *major = ver[0];
+        *minor = ver[1];
+    }
+}
+
+int mbedtls_ssl_set_calc_verify_md( mbedtls_ssl_context *ssl, int md )
+{
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( ssl->minor_ver != MBEDTLS_SSL_MINOR_VERSION_3 )
+        return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+
+    switch( md )
+    {
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
+#if defined(MBEDTLS_MD5_C)
+        case MBEDTLS_SSL_HASH_MD5:
+            return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+#endif
+#if defined(MBEDTLS_SHA1_C)
+        case MBEDTLS_SSL_HASH_SHA1:
+            ssl->handshake->calc_verify = ssl_calc_verify_tls;
+            break;
+#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 */
+#if defined(MBEDTLS_SHA512_C)
+        case MBEDTLS_SSL_HASH_SHA384:
+            ssl->handshake->calc_verify = ssl_calc_verify_tls_sha384;
+            break;
+#endif
+#if defined(MBEDTLS_SHA256_C)
+        case MBEDTLS_SSL_HASH_SHA256:
+            ssl->handshake->calc_verify = ssl_calc_verify_tls_sha256;
+            break;
+#endif
+        default:
+            return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+    }
+
+    return 0;
+#else /* !MBEDTLS_SSL_PROTO_TLS1_2 */
+    (void) ssl;
+    (void) md;
+
+    return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+}
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+int mbedtls_ssl_get_key_exchange_md_ssl_tls( mbedtls_ssl_context *ssl,
+                                        unsigned char *output,
+                                        unsigned char *data, size_t data_len )
+{
+    int ret = 0;
+    mbedtls_md5_context mbedtls_md5;
+    mbedtls_sha1_context mbedtls_sha1;
+
+    mbedtls_md5_init( &mbedtls_md5 );
+    mbedtls_sha1_init( &mbedtls_sha1 );
+
+    /*
+     * digitally-signed struct {
+     *     opaque md5_hash[16];
+     *     opaque sha_hash[20];
+     * };
+     *
+     * md5_hash
+     *     MD5(ClientHello.random + ServerHello.random
+     *                            + ServerParams);
+     * sha_hash
+     *     SHA(ClientHello.random + ServerHello.random
+     *                            + ServerParams);
+     */
+    if( ( ret = mbedtls_md5_starts_ret( &mbedtls_md5 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md5_starts_ret", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_md5_update_ret( &mbedtls_md5,
+                                        ssl->handshake->randbytes, 64 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md5_update_ret", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_md5_update_ret( &mbedtls_md5, data, data_len ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md5_update_ret", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_md5_finish_ret( &mbedtls_md5, output ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md5_finish_ret", ret );
+        goto exit;
+    }
+
+    if( ( ret = mbedtls_sha1_starts_ret( &mbedtls_sha1 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_sha1_starts_ret", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_sha1_update_ret( &mbedtls_sha1,
+                                         ssl->handshake->randbytes, 64 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_sha1_update_ret", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_sha1_update_ret( &mbedtls_sha1, data,
+                                         data_len ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_sha1_update_ret", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_sha1_finish_ret( &mbedtls_sha1,
+                                         output + 16 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_sha1_finish_ret", ret );
+        goto exit;
+    }
+
+exit:
+    mbedtls_md5_free( &mbedtls_md5 );
+    mbedtls_sha1_free( &mbedtls_sha1 );
+
+    if( ret != 0 )
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+
+    return( ret );
+
+}
+#endif /* MBEDTLS_SSL_PROTO_SSL3 || MBEDTLS_SSL_PROTO_TLS1 || \
+          MBEDTLS_SSL_PROTO_TLS1_1 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+int mbedtls_ssl_get_key_exchange_md_tls1_2( mbedtls_ssl_context *ssl,
+                                            unsigned char *hash, size_t *hashlen,
+                                            unsigned char *data, size_t data_len,
+                                            mbedtls_md_type_t md_alg )
+{
+    psa_status_t status;
+    psa_hash_operation_t hash_operation = PSA_HASH_OPERATION_INIT;
+    psa_algorithm_t hash_alg = mbedtls_psa_translate_md( md_alg );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "Perform PSA-based computation of digest of ServerKeyExchange" ) );
+
+    if( ( status = psa_hash_setup( &hash_operation,
+                                   hash_alg ) ) != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_setup", status );
+        goto exit;
+    }
+
+    if( ( status = psa_hash_update( &hash_operation, ssl->handshake->randbytes,
+                                    64 ) ) != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_update", status );
+        goto exit;
+    }
+
+    if( ( status = psa_hash_update( &hash_operation,
+                                    data, data_len ) ) != PSA_SUCCESS )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_update", status );
+        goto exit;
+    }
+
+    if( ( status = psa_hash_finish( &hash_operation, hash, MBEDTLS_MD_MAX_SIZE,
+                                    hashlen ) ) != PSA_SUCCESS )
+    {
+         MBEDTLS_SSL_DEBUG_RET( 1, "psa_hash_finish", status );
+         goto exit;
+    }
+
+exit:
+    if( status != PSA_SUCCESS )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+        switch( status )
+        {
+            case PSA_ERROR_NOT_SUPPORTED:
+                return( MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE );
+            case PSA_ERROR_BAD_STATE: /* Intentional fallthrough */
+            case PSA_ERROR_BUFFER_TOO_SMALL:
+                return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+            case PSA_ERROR_INSUFFICIENT_MEMORY:
+                return( MBEDTLS_ERR_MD_ALLOC_FAILED );
+            default:
+                return( MBEDTLS_ERR_MD_HW_ACCEL_FAILED );
+        }
+    }
+    return( 0 );
+}
+
+#else
+
+int mbedtls_ssl_get_key_exchange_md_tls1_2( mbedtls_ssl_context *ssl,
+                                            unsigned char *hash, size_t *hashlen,
+                                            unsigned char *data, size_t data_len,
+                                            mbedtls_md_type_t md_alg )
+{
+    int ret = 0;
+    mbedtls_md_context_t ctx;
+    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
+    *hashlen = mbedtls_md_get_size( md_info );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "Perform mbedtls-based computation of digest of ServerKeyExchange" ) );
+
+    mbedtls_md_init( &ctx );
+
+    /*
+     * digitally-signed struct {
+     *     opaque client_random[32];
+     *     opaque server_random[32];
+     *     ServerDHParams params;
+     * };
+     */
+    if( ( ret = mbedtls_md_setup( &ctx, md_info, 0 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_setup", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_md_starts( &ctx ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_starts", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_md_update( &ctx, ssl->handshake->randbytes, 64 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_update", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_md_update( &ctx, data, data_len ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_update", ret );
+        goto exit;
+    }
+    if( ( ret = mbedtls_md_finish( &ctx, hash ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_finish", ret );
+        goto exit;
+    }
+
+exit:
+    mbedtls_md_free( &ctx );
+
+    if( ret != 0 )
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+
+    return( ret );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
+          MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#endif /* MBEDTLS_SSL_TLS_C */