Simplify retaining of messages for future processing
There are situations in which it is not clear what message to expect
next. For example, the message following the ServerHello might be
either a Certificate, a ServerKeyExchange or a CertificateRequest. We
deal with this situation in the following way: Initially, the message
processing function for one of the allowed message types is called,
which fetches and decodes a new message. If that message is not the
expected one, the function returns successfully (instead of throwing
an error as usual for unexpected messages), and the handshake
continues to the processing function for the next possible message. To
not have this function fetch a new message, a flag in the SSL context
structure is used to indicate that the last message was retained for
further processing, and if that's set, the following processing
function will not fetch a new record.
This commit simplifies the usage of this message-retaining parameter
by doing the check within the record-fetching routine instead of the
specific message-processing routines. The code gets cleaner this way
and allows retaining messages to be used in other situations as well
without much effort. This will be used in the next commits.
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 616cadc..a2b9f8c 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1471,6 +1471,8 @@
}
MBEDTLS_SSL_DEBUG_MSG( 1, ( "non-handshake message during renego" ) );
+
+ ssl->keep_current_message = 1;
return( MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO );
}
#endif /* MBEDTLS_SSL_RENEGOTIATION */
@@ -2316,13 +2318,17 @@
if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
{
- ssl->record_read = 1;
+ /* Current message is probably either
+ * CertificateRequest or ServerHelloDone */
+ ssl->keep_current_message = 1;
goto exit;
}
- MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "server key exchange message must "
+ "not be skipped" ) );
mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
@@ -2640,38 +2646,32 @@
return( 0 );
}
- if( ssl->record_read == 0 )
+ if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
{
- if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
- {
- MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
- return( ret );
- }
-
- if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
- {
- MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
- mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
- MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
- return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
- }
-
- ssl->record_read = 1;
+ MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+ return( ret );
}
- ssl->client_auth = 0;
- ssl->state++;
+ if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
+ mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+ MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+ return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+ }
- if( ssl->in_msg[0] == MBEDTLS_SSL_HS_CERTIFICATE_REQUEST )
- ssl->client_auth++;
+ ssl->state++;
+ ssl->client_auth = ( ssl->in_msg[0] == MBEDTLS_SSL_HS_CERTIFICATE_REQUEST );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "got %s certificate request",
ssl->client_auth ? "a" : "no" ) );
if( ssl->client_auth == 0 )
+ {
+ /* Current message is probably the ServerHelloDone */
+ ssl->keep_current_message = 1;
goto exit;
-
- ssl->record_read = 0;
+ }
/*
* struct {
@@ -2766,21 +2766,17 @@
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse server hello done" ) );
- if( ssl->record_read == 0 )
+ if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
{
- if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
- {
- MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
- return( ret );
- }
-
- if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
- {
- MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello done message" ) );
- return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
- }
+ MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+ return( ret );
}
- ssl->record_read = 0;
+
+ if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello done message" ) );
+ return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+ }
if( ssl->in_hslen != mbedtls_ssl_hs_hdr_len( ssl ) ||
ssl->in_msg[0] != MBEDTLS_SSL_HS_SERVER_HELLO_DONE )