ssl_write_server_key_exchange refactor: minor cleanup

Clean up some debug messages and improve some comments.
This commit is contained in:
Gilles Peskine 2018-01-08 17:07:44 +01:00
parent ebd30ae205
commit d3eb0619a6

View file

@ -2837,25 +2837,26 @@ static int ssl_resume_server_key_exchange( mbedtls_ssl_context *ssl,
ssl->handshake->p_async_operation_ctx,
ssl->out_msg + ssl->out_msglen + 2,
signature_len, sig_max_len );
MBEDTLS_SSL_DEBUG_RET( 3, "f_async_resume", ret );
if( ret != MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS )
{
ssl->handshake->p_async_operation_ctx = NULL;
}
MBEDTLS_SSL_DEBUG_RET( 2, "ssl_resume_server_key_exchange", ret );
return( ret );
}
#endif /* defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED) &&
defined(MBEDTLS_SSL_ASYNC_PRIVATE_C) */
/* Prepare the ServerKeyExchange message, up to and including
calculating the signature if any, but excluding formatting the
signature and sending the message. */
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;
unsigned char *p = ssl->out_msg + 4;
#if defined(MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED)
size_t len;
#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
unsigned char *dig_signed = NULL;
#endif /* MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED */
@ -2863,8 +2864,6 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
(void) ciphersuite_info; /* unused in some configurations */
(void) signature_len; /* unused in some configurations */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );
/*
*
* Part 1: Provide key exchange parameters for chosen ciphersuite.
@ -2879,6 +2878,7 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
{
int ret;
const unsigned char *end = ssl->out_msg + MBEDTLS_SSL_MAX_CONTENT_LEN;
size_t len;
ret = mbedtls_ecjpake_write_round_two( &ssl->handshake->ecjpake_ctx,
p, end - p, &len, ssl->conf->f_rng, ssl->conf->p_rng );
@ -2915,6 +2915,7 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
if( mbedtls_ssl_ciphersuite_uses_dhe( ciphersuite_info ) )
{
int ret;
size_t len;
if( ssl->conf->dhm_P.p == NULL || ssl->conf->dhm_G.p == NULL )
{
@ -2976,6 +2977,7 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
const mbedtls_ecp_curve_info **curve = NULL;
const mbedtls_ecp_group_id *gid;
int ret;
size_t len;
/* Match our preference list against the offered curves */
for( gid = ssl->conf->curve_list; *gid != MBEDTLS_ECP_DP_NONE; gid++ )
@ -3211,7 +3213,6 @@ curve_matching_done:
case 0:
return( ssl_resume_server_key_exchange( ssl, signature_len ) );
case MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server key exchange (pending)" ) );
return( MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS );
default:
MBEDTLS_SSL_DEBUG_RET( 1, "f_async_sign", ret );
@ -3242,17 +3243,24 @@ curve_matching_done:
return( 0 );
}
/* Prepare the ServerKeyExchange message and send it. For ciphersuites
that do not include a ServerKeyExchange message, do nothing. Either
way, if successful, move on to the next step in the SSL state
machine */
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. */
#if defined(MBEDTLS_KEY_EXCHANGE__SOME_NON_PFS__ENABLED)
const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
ssl->transform_negotiate->ciphersuite_info;
#endif /* MBEDTLS_KEY_EXCHANGE__NON_PFS__ENABLED */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );
#if defined(MBEDTLS_KEY_EXCHANGE__SOME_NON_PFS__ENABLED)
/* Extract static ECDH parameters and abort if ServerKeyExchange
* is not needed. */
if( mbedtls_ssl_ciphersuite_no_pfs( ciphersuite_info ) )
{
/* For suites involving ECDH, extract DH parameters
@ -3272,16 +3280,14 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
}
#endif /* MBEDTLS_KEY_EXCHANGE__NON_PFS__ENABLED */
/* If we have already prepared the message and there is an ongoing
signature operation, resume signing. */
#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED) && \
defined(MBEDTLS_SSL_ASYNC_PRIVATE_C)
/* If we have already prepared the message and there is an ongoing
signature operation, resume signing. */
if( ssl->handshake->p_async_operation_ctx != NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "resuming signature operation" ) );
ret = ssl_resume_server_key_exchange( ssl, &signature_len );
if( ret != 0 )
return( ret );
}
else
#endif /* defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED) &&
@ -3289,8 +3295,15 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
{
/* ServerKeyExchange is needed. Prepare the message. */
ret = ssl_prepare_server_key_exchange( ssl, &signature_len );
if( ret != 0 )
return( ret );
}
if( ret != 0 )
{
if( ret == MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS )
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server key exchange (pending)" ) );
else
ssl->out_msglen = 0;
return( ret );
}
/* If there is a signature, write its length.
@ -3324,7 +3337,6 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server key exchange" ) );
return( 0 );
}