AuroraMiddleware/mbedtls
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Clarify code a bit in write_handshake_msg()

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- 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
This commit is contained in:
Manuel Pégourié-Gonnard 2017-09-13 09:54:27 +02:00
parent 31c1586893
commit 9c3a8caa92
1 changed files with 36 additions and 28 deletions
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64
library/ssl_tls.c
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@ -2938,6 +2938,8 @@ void mbedtls_ssl_send_flight_completed( mbedtls_ssl_context *ssl )
* - 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 @@ void mbedtls_ssl_send_flight_completed( mbedtls_ssl_context *ssl )
*/
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 @@ int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
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 @@ int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
{
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 @@ int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
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 @@ int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
}
#endif
/* Actually send out */
ret = mbedtls_ssl_write_record( ssl );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write handshake message" ) );