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Get rid of memmove for DTLS in parse_client_hello()

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Manuel Pégourié-Gonnard 2014-09-09 17:08:52 +02:00 committed by Paul Bakker
parent 63eca930d7
commit 19d438f4ff
1 changed files with 56 additions and 64 deletions
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120
library/ssl_srv.c
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@ -1275,19 +1275,41 @@ static int ssl_parse_client_hello( ssl_context *ssl )
ssl->handshake->update_checksum( ssl, buf, msg_len );
/*
* The DTLS handshake layer contains additional fields. Use them, then
* remove them so that it looks like TLS format to the rest of the code.
* Handshake layer:
* 0 . 0 handshake type
* 1 . 3 handshake length
* 4 . 5 DTLS only: message seqence number
* 6 . 8 DTLS only: fragment offset
* 9 . 11 DTLS only: fragment length
*/
if( msg_len < ssl_hs_hdr_len( ssl ) )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
SSL_DEBUG_MSG( 3, ( "client hello v3, handshake type: %d", buf[0] ) );
if( buf[0] != SSL_HS_CLIENT_HELLO )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
SSL_DEBUG_MSG( 3, ( "client hello v3, handshake len.: %d",
( buf[1] << 16 ) | ( buf[2] << 8 ) | buf[3] ) );
/* We don't support fragmentation of ClientHello (yet?) */
if( buf[1] != 0 ||
msg_len != ssl_hs_hdr_len( ssl ) + ( ( buf[2] << 8 ) | buf[3] ) )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
#if defined(POLARSSL_SSL_PROTO_DTLS)
if( ssl->transport == SSL_TRANSPORT_DATAGRAM )
{
/* 1 (type) + 3 (len) + 2 (seq) + 3 (frag_offset) + 3 (frag_len) */
if( msg_len < 12 )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
/*
* Copy the client's handshake message_seq on initial handshakes
*/
@ -1318,68 +1340,41 @@ static int ssl_parse_client_hello( ssl_context *ssl )
/*
* For now we don't support fragmentation, so make sure
* fragment_offset == 0 and fragment_length == length
*
* TODO: DTLS: support fragmentation??
* Well, ClientHello is rarely much longer than 512 bytes
* so it will probably never be fragmented anyway...
*/
if( ssl->in_msg[6] != 0 || ssl->in_msg[7] != 0 || ssl->in_msg[8] != 0 ||
memcmp( ssl->in_msg + 1, ssl->in_msg + 9, 3 ) != 0 )
{
SSL_DEBUG_MSG( 1, ( "handshake fragmentation not supported" ) );
SSL_DEBUG_MSG( 1, ( "ClientHello fragmentation not supported" ) );
return( POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE );
}
/* Remove the additional fields */
memmove( buf + 4, buf + 12, msg_len - 12 );
msg_len -= 8;
}
#endif /* POLARSSL_SSL_PROTO_DTLS */
buf += ssl_hs_hdr_len( ssl );
msg_len -= ssl_hs_hdr_len( ssl );
/*
* SSL layer:
* 0 . 0 handshake type
* 1 . 3 handshake length
* 4 . 5 protocol version
* 6 . 37 random bytes (starting with 4 bytes of Unix time)
* 38 . 38 session id length (1 byte)
* 39 . 38+x session id
* 39+x . 39+x DTLS only: cookie length (1 byte)
* 40+x . .. DTSL only: cookie
* ClientHello layer:
* 0 . 1 protocol version
* 2 . 33 random bytes (starting with 4 bytes of Unix time)
* 34 . 35 session id length (1 byte)
* 35 . 34+x session id
* 35+x . 35+x DTLS only: cookie length (1 byte)
* 36+x . .. DTLS only: cookie
* .. . .. ciphersuite list length (2 bytes)
* .. . .. ciphersuite list
* .. . .. compression alg. list length (1 byte)
* .. . .. compression alg. list
* .. . .. extensions length (2 bytes, optional)
* .. . .. extensions (optional)
*
* Minimal length (with everything empty and extensions ommitted) is
* 4 + 2 + 32 + 1 + 2 + 1 = 42 bytes. Check that first, so that we can
* read at least up to session id length without worrying.
*/
/*
* Check the handshake type and message length
* Minimal length (with everything empty and extensions ommitted) is
* 2 + 32 + 1 + 2 + 1 = 38 bytes. Check that first, so that we can
* read at least up to session id length without worrying.
*/
if( msg_len < 42 )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
SSL_DEBUG_MSG( 3, ( "client hello v3, handshake type: %d", buf[0] ) );
if( buf[0] != SSL_HS_CLIENT_HELLO )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
SSL_DEBUG_MSG( 3, ( "client hello v3, handshake len.: %d",
( buf[1] << 16 ) | ( buf[2] << 8 ) | buf[3] ) );
if( buf[1] != 0 ||
msg_len != (unsigned int) 4 + ( ( buf[2] << 8 ) | buf[3] ) )
if( msg_len < 38 )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
@ -1388,11 +1383,10 @@ static int ssl_parse_client_hello( ssl_context *ssl )
/*
* Check and save the protocol version
*/
SSL_DEBUG_MSG( 3, ( "client hello v3, max. version: [%d:%d]",
buf[4], buf[5] ) );
SSL_DEBUG_BUF( 3, "client hello, version", buf, 2 );
ssl_read_version( &ssl->major_ver, &ssl->minor_ver,
ssl->transport, buf + 4 );
ssl->transport, buf );
ssl->handshake->max_major_ver = ssl->major_ver;
ssl->handshake->max_minor_ver = ssl->minor_ver;
@ -1422,30 +1416,28 @@ static int ssl_parse_client_hello( ssl_context *ssl )
/*
* Save client random (inc. Unix time)
*/
SSL_DEBUG_BUF( 3, "client hello, random bytes",
buf + 6, 32 );
SSL_DEBUG_BUF( 3, "client hello, random bytes", buf + 2, 32 );
memcpy( ssl->handshake->randbytes, buf + 6, 32 );
memcpy( ssl->handshake->randbytes, buf + 2, 32 );
/*
* Check the session ID length and save session ID
*/
sess_len = buf[38];
sess_len = buf[34];
if( sess_len > sizeof( ssl->session_negotiate->id ) ||
sess_len + 38 + 2 > msg_len ) /* 2 for cipherlist length field */
sess_len + 34 + 2 > msg_len ) /* 2 for cipherlist length field */
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
SSL_DEBUG_BUF( 3, "client hello, session id",
buf + 39, sess_len );
SSL_DEBUG_BUF( 3, "client hello, session id", buf + 35, sess_len );
ssl->session_negotiate->length = sess_len;
memset( ssl->session_negotiate->id, 0,
sizeof( ssl->session_negotiate->id ) );
memcpy( ssl->session_negotiate->id, buf + 39,
memcpy( ssl->session_negotiate->id, buf + 35,
ssl->session_negotiate->length );
/*
@ -1454,7 +1446,7 @@ static int ssl_parse_client_hello( ssl_context *ssl )
#if defined(POLARSSL_SSL_PROTO_DTLS)
if( ssl->transport == SSL_TRANSPORT_DATAGRAM )
{
cookie_offset = 39 + sess_len;
cookie_offset = 35 + sess_len;
cookie_len = buf[cookie_offset];
if( cookie_offset + 1 + cookie_len + 2 > msg_len )
@ -1506,7 +1498,7 @@ static int ssl_parse_client_hello( ssl_context *ssl )
ciph_offset = cookie_offset + 1 + cookie_len;
else
#endif
ciph_offset = 39 + sess_len;
ciph_offset = 35 + sess_len;
ciph_len = ( buf[ciph_offset + 0] << 8 )
| ( buf[ciph_offset + 1] );