ssl_write_server_key_exchange refactor: move signature_len out

Move the writing of signature_len out of
ssl_prepare_server_key_exchange. This simplifies the control flow (one
less goto).
This commit is contained in:
Gilles Peskine 2018-01-08 17:04:16 +01:00
parent 1004c19ed0
commit 7ab013a08a

View file

@ -2826,7 +2826,8 @@ static int ssl_get_ecdh_params_from_cert( mbedtls_ssl_context *ssl )
#endif /* MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) ||
MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED */
static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl )
static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
size_t *signature_len )
{
const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
ssl->transform_negotiate->ciphersuite_info;
@ -2839,6 +2840,7 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl )
#endif /* MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED */
#endif /* MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED */
(void) ciphersuite_info; /* unused in some configurations */
(void) signature_len; /* unused in some configurations */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );
@ -3018,7 +3020,6 @@ curve_matching_done:
if( mbedtls_ssl_ciphersuite_uses_server_signature( ciphersuite_info ) )
{
size_t dig_signed_len = ssl->out_msg + ssl->out_msglen - dig_signed;
size_t signature_len = 0;
unsigned int hashlen = 0;
unsigned char hash[MBEDTLS_MD_MAX_SIZE];
int ret;
@ -3205,16 +3206,12 @@ curve_matching_done:
ssl->conf->p_async_connection_ctx,
ssl->handshake->p_async_operation_ctx,
ssl->out_msg + ssl->out_msglen + 2,
&signature_len, sig_max_len );
signature_len, sig_max_len );
if( ret != MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS )
{
ssl->handshake->p_async_operation_ctx = NULL;
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "f_async_resume", ret );
return( ret );
}
goto have_signature;
MBEDTLS_SSL_DEBUG_RET( 1, "f_async_resume", ret );
return( ret );
}
/* FALLTHROUGH */
case MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS:
@ -3237,25 +3234,13 @@ curve_matching_done:
if( ( ret = mbedtls_pk_sign( mbedtls_ssl_own_key( ssl ),
md_alg, hash, hashlen,
ssl->out_msg + ssl->out_msglen + 2,
&signature_len,
signature_len,
ssl->conf->f_rng,
ssl->conf->p_rng ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_pk_sign", ret );
return( ret );
}
#if defined(MBEDTLS_SSL_ASYNC_PRIVATE_C)
have_signature:
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE_C */
ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len >> 8 );
ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len );
MBEDTLS_SSL_DEBUG_BUF( 3, "my signature",
ssl->out_msg + ssl->out_msglen,
signature_len );
ssl->out_msglen += signature_len;
}
#endif /* MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED */
@ -3265,6 +3250,7 @@ curve_matching_done:
static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
{
int ret;
size_t signature_len = 0;
/* Extract static ECDH parameters and abort if ServerKeyExchange
* is not needed. */
@ -3292,10 +3278,28 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
#endif /* MBEDTLS_KEY_EXCHANGE__NON_PFS__ENABLED */
/* ServerKeyExchange is needed. Prepare the message. */
ret = ssl_prepare_server_key_exchange( ssl );
ret = ssl_prepare_server_key_exchange( ssl, &signature_len );
if( ret != 0 )
return( ret );
/* If there is a signature, write its length.
ssl_prepare_server_key_exchange already wrote the signature
itself at its proper place in the output buffer. */
#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
if( signature_len != 0 )
{
ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len >> 8 );
ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len );
MBEDTLS_SSL_DEBUG_BUF( 3, "my signature",
ssl->out_msg + ssl->out_msglen,
signature_len );
/* Skip over the already-written signature */
ssl->out_msglen += signature_len;
}
#endif /* MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED */
/* Add header and send. */
ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
ssl->out_msg[0] = MBEDTLS_SSL_HS_SERVER_KEY_EXCHANGE;