Remove ciphersuite_info from ssl_transform

Prior to this commit, the security parameter struct `ssl_transform`
contained a `ciphersuite_info` field pointing to the information
structure for the negotiated ciphersuite. However, the only
information extracted from that structure that was used in the core
encryption and decryption functions `ssl_encrypt_buf`/`ssl_decrypt_buf`
was the authentication tag length in case of an AEAD cipher.

The present commit removes the `ciphersuite_info` field from the
`ssl_transform` structure and adds an explicit `taglen` field
for AEAD authentication tag length.

This is in accordance with the principle that the `ssl_transform`
structure should contain the raw parameters needed for the record
encryption and decryption functions to work, but not the higher-level
information that gave rise to them. For example, the `ssl_transform`
structure implicitly contains the encryption/decryption keys within
their cipher contexts, but it doesn't contain the SSL master or
premaster secrets. Likewise, it contains an explicit `maclen`, while
the status of the 'Truncated HMAC' extension -- which  determines the
value of `maclen` when the `ssl_transform` structure is created in
`ssl_derive_keys` -- is not contained in `ssl_transform`.

The `ciphersuite_info` pointer was used in other places outside
the encryption/decryption functions during the handshake, and for
these functions to work, this commit adds a `ciphersuite_info` pointer
field to the handshake-local `ssl_handshake_params` structure.
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index afced7a..ad7378f 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1312,7 +1312,7 @@
 {
     int ret;
 
-    if( ssl->transform_negotiate->ciphersuite_info->key_exchange !=
+    if( ssl->handshake->ciphersuite_info->key_exchange !=
         MBEDTLS_KEY_EXCHANGE_ECJPAKE )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip ecjpake kkpp extension" ) );
@@ -1675,9 +1675,8 @@
     /*
      * Initialize update checksum functions
      */
-    ssl->transform_negotiate->ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( i );
-
-    if( ssl->transform_negotiate->ciphersuite_info == NULL )
+    ssl->handshake->ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( i );
+    if( ssl->handshake->ciphersuite_info == NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "ciphersuite info for %04x not found", i ) );
         mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
@@ -1685,7 +1684,7 @@
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
     }
 
-    mbedtls_ssl_optimize_checksum( ssl, ssl->transform_negotiate->ciphersuite_info );
+    mbedtls_ssl_optimize_checksum( ssl, ssl->handshake->ciphersuite_info );
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, session id len.: %d", n ) );
     MBEDTLS_SSL_DEBUG_BUF( 3,   "server hello, session id", buf + 35, n );
@@ -2330,7 +2329,7 @@
 {
     int ret;
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
     unsigned char *p = NULL, *end = NULL;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse server key exchange" ) );
@@ -2670,7 +2669,7 @@
 static int ssl_parse_certificate_request( mbedtls_ssl_context *ssl )
 {
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate request" ) );
 
@@ -2692,7 +2691,7 @@
     size_t n = 0;
     size_t cert_type_len = 0, dn_len = 0;
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate request" ) );
 
@@ -2893,7 +2892,7 @@
     int ret;
     size_t i, n;
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write client key exchange" ) );
 
@@ -3183,7 +3182,7 @@
 static int ssl_write_certificate_verify( mbedtls_ssl_context *ssl )
 {
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
     int ret;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate verify" ) );
@@ -3213,7 +3212,7 @@
 {
     int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
     size_t n = 0, offset = 0;
     unsigned char hash[48];
     unsigned char *hash_start = hash;
@@ -3323,8 +3322,7 @@
          * Reason: Otherwise we should have running hashes for SHA512 and SHA224
          *         in order to satisfy 'weird' needs from the server side.
          */
-        if( ssl->transform_negotiate->ciphersuite_info->mac ==
-            MBEDTLS_MD_SHA384 )
+        if( ssl->handshake->ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
         {
             md_alg = MBEDTLS_MD_SHA384;
             ssl->out_msg[4] = MBEDTLS_SSL_HASH_SHA384;
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index bc77f80..72d3c79 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1155,7 +1155,7 @@
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "selected ciphersuite: %s", ciphersuite_info->name ) );
 
     ssl->session_negotiate->ciphersuite = ciphersuites[i];
-    ssl->transform_negotiate->ciphersuite_info = ciphersuite_info;
+    ssl->handshake->ciphersuite_info = ciphersuite_info;
 
     /*
      * SSLv2 Client Hello relevant renegotiation security checks
@@ -1999,7 +1999,7 @@
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "selected ciphersuite: %s", ciphersuite_info->name ) );
 
     ssl->session_negotiate->ciphersuite = ciphersuites[i];
-    ssl->transform_negotiate->ciphersuite_info = ciphersuite_info;
+    ssl->handshake->ciphersuite_info = ciphersuite_info;
 
     ssl->state++;
 
@@ -2266,7 +2266,7 @@
     *olen = 0;
 
     /* Skip costly computation if not needed */
-    if( ssl->transform_negotiate->ciphersuite_info->key_exchange !=
+    if( ssl->handshake->ciphersuite_info->key_exchange !=
         MBEDTLS_KEY_EXCHANGE_ECJPAKE )
         return;
 
@@ -2649,7 +2649,7 @@
 static int ssl_write_certificate_request( mbedtls_ssl_context *ssl )
 {
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate request" ) );
 
@@ -2672,7 +2672,7 @@
 {
     int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
     size_t dn_size, total_dn_size; /* excluding length bytes */
     size_t ct_len, sa_len; /* including length bytes */
     unsigned char *buf, *p;
@@ -2899,7 +2899,8 @@
                                             size_t *signature_len )
 {
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-                            ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
+
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED)
 #if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
     unsigned char *dig_signed = NULL;
@@ -3265,7 +3266,7 @@
     size_t signature_len = 0;
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME_NON_PFS__ENABLED)
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-                            ssl->transform_negotiate->ciphersuite_info;
+                            ssl->handshake->ciphersuite_info;
 #endif /* MBEDTLS_KEY_EXCHANGE__SOME_NON_PFS__ENABLED */
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );
@@ -3711,7 +3712,7 @@
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
     unsigned char *p, *end;
 
-    ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
+    ciphersuite_info = ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse client key exchange" ) );
 
@@ -3994,7 +3995,7 @@
 static int ssl_parse_certificate_verify( mbedtls_ssl_context *ssl )
 {
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate verify" ) );
 
@@ -4025,7 +4026,7 @@
 #endif
     mbedtls_md_type_t md_alg;
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
-        ssl->transform_negotiate->ciphersuite_info;
+        ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate verify" ) );
 
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index ef0828b..9817749 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -619,6 +619,7 @@
     size_t mac_key_len;
     size_t iv_copy_len;
     unsigned keylen;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
     const mbedtls_cipher_info_t *cipher_info;
     const mbedtls_md_info_t *md_info;
 
@@ -628,19 +629,20 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> derive keys" ) );
 
-    cipher_info = mbedtls_cipher_info_from_type( transform->ciphersuite_info->cipher );
+    ciphersuite_info = handshake->ciphersuite_info;
+    cipher_info = mbedtls_cipher_info_from_type( ciphersuite_info->cipher );
     if( cipher_info == NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "cipher info for %d not found",
-                            transform->ciphersuite_info->cipher ) );
+                                    ciphersuite_info->cipher ) );
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
     }
 
-    md_info = mbedtls_md_info_from_type( transform->ciphersuite_info->mac );
+    md_info = mbedtls_md_info_from_type( ciphersuite_info->mac );
     if( md_info == NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "mbedtls_md info for %d not found",
-                            transform->ciphersuite_info->mac ) );
+                            ciphersuite_info->mac ) );
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
     }
 
@@ -668,7 +670,7 @@
 #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 )
+        ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
     {
         handshake->tls_prf = tls_prf_sha384;
         handshake->calc_verify = ssl_calc_verify_tls_sha384;
@@ -720,8 +722,7 @@
             if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
             {
 #if defined(MBEDTLS_SHA512_C)
-                if( ssl->transform_negotiate->ciphersuite_info->mac ==
-                    MBEDTLS_MD_SHA384 )
+                if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
                 {
                     hash_len = 48;
                 }
@@ -811,10 +812,12 @@
         cipher_info->mode == MBEDTLS_MODE_CCM ||
         cipher_info->mode == MBEDTLS_MODE_CHACHAPOLY )
     {
-        size_t taglen, explicit_ivlen;
+        size_t explicit_ivlen;
 
         transform->maclen = 0;
         mac_key_len = 0;
+        transform->taglen =
+            ciphersuite_info->flags & MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16;
 
         /* All modes haves 96-bit IVs;
          * GCM and CCM has 4 implicit and 8 explicit bytes
@@ -826,14 +829,9 @@
         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;
+        transform->minlen = explicit_ivlen + transform->taglen;
     }
     else
     {
@@ -1560,8 +1558,6 @@
         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;
 
         /*
@@ -1628,7 +1624,8 @@
                                          add_data, 13,
                                          enc_msg, enc_msglen,
                                          enc_msg, &olen,
-                                         enc_msg + enc_msglen, taglen ) ) != 0 )
+                                         enc_msg + enc_msglen,
+                                         transform->taglen ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_encrypt", ret );
             return( ret );
@@ -1640,10 +1637,11 @@
             return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
         }
 
-        ssl->out_msglen += taglen;
+        ssl->out_msglen += ssl->transform_out->taglen;
         auth_done++;
 
-        MBEDTLS_SSL_DEBUG_BUF( 4, "after encrypt: tag", enc_msg + enc_msglen, taglen );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "after encrypt: tag", enc_msg + enc_msglen,
+                               ssl->transform_out->taglen );
     }
     else
 #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
@@ -1851,21 +1849,19 @@
         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 )
+        if( ssl->in_msglen < explicit_iv_len + transform->taglen )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) < explicit_iv_len (%d) "
                                 "+ taglen (%d)", ssl->in_msglen,
-                                explicit_iv_len, taglen ) );
+                                explicit_iv_len, transform->taglen ) );
             return( MBEDTLS_ERR_SSL_INVALID_MAC );
         }
-        dec_msglen = ssl->in_msglen - explicit_iv_len - taglen;
+        dec_msglen = ssl->in_msglen - explicit_iv_len - transform->taglen;
 
         dec_msg = ssl->in_msg;
         dec_msg_result = ssl->in_msg;
@@ -1911,7 +1907,8 @@
         }
 
         MBEDTLS_SSL_DEBUG_BUF( 4, "IV used", iv, transform->ivlen );
-        MBEDTLS_SSL_DEBUG_BUF( 4, "TAG used", dec_msg + dec_msglen, taglen );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "TAG used", dec_msg + dec_msglen,
+                               transform->taglen );
 
         /*
          * Decrypt and authenticate
@@ -1921,7 +1918,8 @@
                                          add_data, 13,
                                          dec_msg, dec_msglen,
                                          dec_msg_result, &olen,
-                                         dec_msg + dec_msglen, taglen ) ) != 0 )
+                                         dec_msg + dec_msglen,
+                                         transform->taglen ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_decrypt", ret );
 
@@ -2237,7 +2235,7 @@
             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 )
+            switch( ssl->handshake->ciphersuite_info->mac )
             {
 #if defined(MBEDTLS_MD5_C) || defined(MBEDTLS_SHA1_C) || \
     defined(MBEDTLS_SHA256_C)
@@ -5281,7 +5279,7 @@
 /* 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;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
 
@@ -5301,7 +5299,7 @@
 
 int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
 {
-    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
 
@@ -5327,7 +5325,7 @@
     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;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->handshake->ciphersuite_info;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
 
@@ -5645,7 +5643,7 @@
 {
     int ret;
     const mbedtls_ssl_ciphersuite_t * const ciphersuite_info =
-          ssl->transform_negotiate->ciphersuite_info;
+          ssl->handshake->ciphersuite_info;
 #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