Implement support for MTU setting
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 4b124ba..7b2ab0f 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2845,16 +2845,20 @@
*/
int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
{
-#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
- const size_t max_record_content_len = mbedtls_ssl_get_max_frag_len( ssl );
-#else
- const size_t max_record_content_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
-#endif
+ const int ret_payload = mbedtls_ssl_get_max_out_record_payload( ssl );
+ const size_t max_record_payload = (size_t) ret_payload;
/* DTLS handshake headers are 12 bytes */
- const size_t max_hs_fragment_len = max_record_content_len - 12;
+ const size_t max_hs_fragment_len = max_record_payload - 12;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_flight_transmit" ) );
+ if( ret_payload < 0 )
+ {
+ MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_get_max_out_record_payload",
+ ret_payload );
+ return( ret_payload );
+ }
+
if( ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialise fligh transmission" ) );
@@ -7008,6 +7012,7 @@
#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 ) )
@@ -7055,10 +7060,45 @@
max_len = ssl_mfl_code_to_length( ssl->session_negotiate->mfl_code );
}
- return max_len;
+ return( max_len );
}
#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+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)
+ 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->conf->mtu != 0 )
+ {
+ const size_t mtu = ssl->conf->mtu;
+ 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
+
+ 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 )
{
@@ -7610,12 +7650,15 @@
static int ssl_write_real( mbedtls_ssl_context *ssl,
const unsigned char *buf, size_t len )
{
- int ret;
-#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
- size_t max_len = mbedtls_ssl_get_max_frag_len( ssl );
-#else
- size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
-#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+ 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)