Clarify code a bit in write_handshake_msg()
- take advantage of the fact that we're only called for first send
- put all sanity checks at the top
- rename and constify shortcut variables
- improve comments
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 464cf69..b66b4fe 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2938,6 +2938,8 @@
* - DTLS: save message for resending
* - then pass to the record layer
*
+ * DTLS: only used when first writing the message, not for resending.
+ *
* Inputs:
* - ssl->out_msglen: 4 + actual handshake message len
* (4 is the size of handshake headers for TLS)
@@ -2951,11 +2953,15 @@
*/
int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
{
- int ret, out_msg_type;
- size_t len = ssl->out_msglen;
+ 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 )
{
@@ -2963,29 +2969,32 @@
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
+ 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 )
{
- ; /* Skip special handshake treatment when resending */
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+ return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
- else
#endif
+
+ /*
+ * Fill handshake headers
+ */
if( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
{
- out_msg_type = ssl->out_msg[0];
-
- if( out_msg_type != MBEDTLS_SSL_HS_HELLO_REQUEST &&
- ssl->handshake == NULL )
- {
- MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
- return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
- }
-
- ssl->out_msg[1] = (unsigned char)( ( len - 4 ) >> 16 );
- ssl->out_msg[2] = (unsigned char)( ( len - 4 ) >> 8 );
- ssl->out_msg[3] = (unsigned char)( ( len - 4 ) );
+ 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,
@@ -3002,17 +3011,16 @@
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS handshake message too large: "
"size %u, maximum %u",
- (unsigned) ( ssl->in_hslen - 4 ),
+ (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, len - 4 );
+ memmove( ssl->out_msg + 12, ssl->out_msg + 4, hs_len );
ssl->out_msglen += 8;
- len += 8;
/* Write message_seq and update it, except for HelloRequest */
- if( out_msg_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
+ 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;
@@ -3024,23 +3032,22 @@
ssl->out_msg[5] = 0;
}
- /* We don't fragment, so frag_offset = 0 and frag_len = len */
+ /* 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 */
- if( out_msg_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
- ssl->handshake->update_checksum( ssl, ssl->out_msg, len );
+ /* Update running hashes of hanshake messages seen */
+ if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
+ ssl->handshake->update_checksum( ssl, ssl->out_msg, ssl->out_msglen );
}
- /* Save handshake and CCS messages for resending */
+ /* Save for resending */
#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 &&
- ( ssl->out_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC ||
- ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE ) )
+ hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
{
if( ( ret = ssl_flight_append( ssl ) ) != 0 )
{
@@ -3050,6 +3057,7 @@
}
#endif
+ /* Actually send out */
ret = mbedtls_ssl_write_record( ssl );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write handshake message" ) );