Introduce buffering structure for handshake messages

This commit introduces, but does not yet put to use, a sub-structure
of mbedtls_ssl_handshake_params::buffering that will be used for the
buffering and/or reassembly of handshake messages with handshake
sequence numbers that are greater or equal to the next expected
sequence number.
This commit is contained in:
Hanno Becker 2018-08-16 13:23:47 +01:00
parent d7f8ae2508
commit 0271f967d6
2 changed files with 68 additions and 3 deletions

View file

@ -155,6 +155,9 @@
#define MBEDTLS_SSL_OUT_PAYLOAD_LEN ( MBEDTLS_SSL_PAYLOAD_OVERHEAD + \
( MBEDTLS_SSL_OUT_CONTENT_LEN ) )
/* The maximum number of buffered handshake messages. */
#define MBEDTLS_SSL_MAX_BUFFERED_HS 2
/* Maximum length we can advertise as our max content length for
RFC 6066 max_fragment_length extension negotiation purposes
(the lesser of both sizes, if they are unequal.)
@ -313,6 +316,14 @@ struct mbedtls_ssl_handshake_params
uint8_t seen_ccs; /*!< Indicates if a CCS message has
* been seen in the current flight. */
struct mbedtls_ssl_hs_buffer
{
uint8_t is_valid : 1;
uint8_t is_fragmented : 1;
uint8_t is_complete : 1;
unsigned char *data;
} hs[MBEDTLS_SSL_MAX_BUFFERED_HS];
} buffering;
#endif /* MBEDTLS_SSL_PROTO_DTLS */
@ -372,6 +383,8 @@ struct mbedtls_ssl_handshake_params
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
};
typedef struct mbedtls_ssl_hs_buffer mbedtls_ssl_hs_buffer;
/*
* This structure contains a full set of runtime transform parameters
* either in negotiation or active.

View file

@ -167,6 +167,8 @@ static int ssl_get_remaining_payload_in_datagram( mbedtls_ssl_context const *ssl
return( (int) remaining );
}
static void ssl_buffering_free( mbedtls_ssl_context *ssl );
/*
* Double the retransmit timeout value, within the allowed range,
* returning -1 if the maximum value has already been reached.
@ -3072,6 +3074,9 @@ void mbedtls_ssl_recv_flight_completed( mbedtls_ssl_context *ssl )
/* We don't want to remember CCS's across flight boundaries. */
ssl->handshake->buffering.seen_ccs = 0;
/* Clear future message buffering structure. */
ssl_buffering_free( ssl );
/* Cancel timer */
ssl_set_timer( ssl, 0 );
@ -3747,9 +3752,9 @@ int mbedtls_ssl_prepare_handshake_record( mbedtls_ssl_context *ssl )
void mbedtls_ssl_update_handshake_status( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER &&
ssl->handshake != NULL )
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER && hs != NULL )
{
ssl->handshake->update_checksum( ssl, ssl->in_msg, ssl->in_hslen );
}
@ -3759,7 +3764,8 @@ void mbedtls_ssl_update_handshake_status( mbedtls_ssl_context *ssl )
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl->handshake != NULL )
{
ssl->handshake->in_msg_seq++;
unsigned offset;
mbedtls_ssl_hs_buffer *hs_buf;
/* Clear up handshake reassembly structure, if any. */
if( ssl->handshake->hs_msg != NULL )
@ -3767,6 +3773,28 @@ void mbedtls_ssl_update_handshake_status( mbedtls_ssl_context *ssl )
mbedtls_free( ssl->handshake->hs_msg );
ssl->handshake->hs_msg = NULL;
}
/* Increment handshake sequence number */
hs->in_msg_seq++;
/*
* Clear up handshake buffering and reassembly structure.
*/
/* Free first entry */
hs_buf = &hs->buffering.hs[0];
if( hs_buf->is_valid )
mbedtls_free( hs_buf->data );
/* Shift all other entries */
for( offset = 0; offset + 1 < MBEDTLS_SSL_MAX_BUFFERED_HS;
offset++, hs_buf++ )
{
*hs_buf = *(hs_buf + 1);
}
/* Create a fresh last entry */
memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
}
#endif
}
@ -8286,6 +8314,29 @@ static void ssl_key_cert_free( mbedtls_ssl_key_cert *key_cert )
}
#endif /* MBEDTLS_X509_CRT_PARSE_C */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
static void ssl_buffering_free( mbedtls_ssl_context *ssl )
{
unsigned offset;
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
if( hs == NULL )
return;
for( offset = 0; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++ )
{
mbedtls_ssl_hs_buffer *hs_buf = &hs->buffering.hs[offset];
if( hs_buf->is_valid == 1 )
{
mbedtls_free( hs_buf->data );
memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
}
}
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
@ -8367,6 +8418,7 @@ void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
mbedtls_free( handshake->verify_cookie );
mbedtls_free( handshake->hs_msg );
ssl_flight_free( handshake->flight );
ssl_buffering_free( ssl );
#endif
mbedtls_platform_zeroize( handshake,