Change write_sig_alg_ext of tls12
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index a6f9e7d..023fac6 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -204,67 +204,15 @@
*/
#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
+
static int ssl_write_sig_alg_ext( mbedtls_ssl_context *ssl, unsigned char *buf,
- const unsigned char *end, size_t *olen )
+ const unsigned char *end, size_t *out_len )
{
unsigned char *p = buf;
- size_t sig_alg_len = 0;
- const int *md = mbedtls_ssl_conf_get_sig_algs( ssl->conf );
+ unsigned char *supported_sig_alg; /* Start of supported_signature_algorithms */
+ size_t supported_sig_alg_len = 0; /* Length of supported_signature_algorithms */
-#if defined(MBEDTLS_RSA_C) || defined(MBEDTLS_ECDSA_C)
- unsigned char *sig_alg_list = buf + 6;
-#endif
-
- *olen = 0;
-
- if( ssl->conf->max_minor_ver != MBEDTLS_SSL_MINOR_VERSION_3 )
- return( 0 );
-
- MBEDTLS_SSL_DEBUG_MSG( 3,
- ( "client hello, adding signature_algorithms extension" ) );
-
- if( md == NULL )
- return( MBEDTLS_ERR_SSL_BAD_CONFIG );
-
- for( ; *md != MBEDTLS_MD_NONE; md++ )
- {
-#if defined(MBEDTLS_ECDSA_C)
- sig_alg_len += 2;
-#endif
-#if defined(MBEDTLS_RSA_C)
- sig_alg_len += 2;
-#endif
- if( sig_alg_len > MBEDTLS_SSL_MAX_SIG_HASH_ALG_LIST_LEN )
- {
- MBEDTLS_SSL_DEBUG_MSG( 3,
- ( "length in bytes of sig-hash-alg extension too big" ) );
- return( MBEDTLS_ERR_SSL_BAD_CONFIG );
- }
- }
-
- /* Empty signature algorithms list, this is a configuration error. */
- if( sig_alg_len == 0 )
- return( MBEDTLS_ERR_SSL_BAD_CONFIG );
-
- MBEDTLS_SSL_CHK_BUF_PTR( p, end, sig_alg_len + 6 );
-
- /*
- * Prepare signature_algorithms extension (TLS 1.2)
- */
- sig_alg_len = 0;
-
- for( md = mbedtls_ssl_conf_get_sig_algs( ssl->conf );
- *md != MBEDTLS_MD_NONE; md++ )
- {
-#if defined(MBEDTLS_ECDSA_C)
- sig_alg_list[sig_alg_len++] = mbedtls_ssl_hash_from_md_alg( *md );
- sig_alg_list[sig_alg_len++] = MBEDTLS_SSL_SIG_ECDSA;
-#endif
-#if defined(MBEDTLS_RSA_C)
- sig_alg_list[sig_alg_len++] = mbedtls_ssl_hash_from_md_alg( *md );
- sig_alg_list[sig_alg_len++] = MBEDTLS_SSL_SIG_RSA;
-#endif
- }
+ *out_len = 0;
/*
* enum {
@@ -283,16 +231,47 @@
* SignatureAndHashAlgorithm
* supported_signature_algorithms<2..2^16-2>;
*/
- MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SIG_ALG, p, 0 );
- p += 2;
- MBEDTLS_PUT_UINT16_BE( sig_alg_len + 2, p, 0 );
- p += 2;
+ MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding signature_algorithms extension" ) );
- MBEDTLS_PUT_UINT16_BE( sig_alg_len, p, 0 );
- p += 2;
+ /* Check if we have space for header and length field:
+ * - extension_type (2 bytes)
+ * - extension_data_length (2 bytes)
+ * - supported_signature_algorithms_length (2 bytes)
+ */
+ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
+ p += 6;
- *olen = 6 + sig_alg_len;
+ /*
+ * Write supported_signature_algorithms
+ */
+ supported_sig_alg = p;
+ for( const uint16_t *sig_alg = mbedtls_ssl_conf_get_sig_algs( ssl->conf );
+ *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++ )
+ {
+ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+ MBEDTLS_PUT_UINT16_BE( *sig_alg, p, 0 );
+ p += 2;
+ MBEDTLS_SSL_DEBUG_MSG( 3, ( "signature scheme [%x]", *sig_alg ) );
+ }
+
+ /* Length of supported_signature_algorithms */
+ supported_sig_alg_len = p - supported_sig_alg;
+ if( supported_sig_alg_len == 0 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "No signature algorithms defined." ) );
+ return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+ }
+
+ /* Write extension_type */
+ MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SIG_ALG, buf, 0 );
+ /* Write extension_data_length */
+ MBEDTLS_PUT_UINT16_BE( supported_sig_alg_len + 2, buf, 2 );
+ /* Write length of supported_signature_algorithms */
+ MBEDTLS_PUT_UINT16_BE( supported_sig_alg_len, buf, 4 );
+
+ /* Output the total length of signature algorithms extension. */
+ *out_len = p - buf;
return( 0 );
}