Merge pull request #5351 from yuhaoth/pr/remove-duplicate-supported_group_ext

Remove duplicate function for writing supported_groups extension
2025-08-02 21:06:37 +03:00 · 2022-01-17 09:13:14 +01:00
parent 73839e02a7 d491ea4f18
commit 188ed19456
7 changed files with 279 additions and 289 deletions
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@ -7195,4 +7195,129 @@ int mbedtls_ssl_get_handshake_transcript( mbedtls_ssl_context *ssl,
 }
 #endif /* !MBEDTLS_USE_PSA_CRYPTO */

+#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) || \
+    defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+/*
+ * Function for writing a supported groups (TLS 1.3) or supported elliptic
+ * curves (TLS 1.2) extension.
+ *
+ * The "extension_data" field of a supported groups extension contains a
+ * "NamedGroupList" value (TLS 1.3 RFC8446):
+ *      enum {
+ *          secp256r1(0x0017), secp384r1(0x0018), secp521r1(0x0019),
+ *          x25519(0x001D), x448(0x001E),
+ *          ffdhe2048(0x0100), ffdhe3072(0x0101), ffdhe4096(0x0102),
+ *          ffdhe6144(0x0103), ffdhe8192(0x0104),
+ *          ffdhe_private_use(0x01FC..0x01FF),
+ *          ecdhe_private_use(0xFE00..0xFEFF),
+ *          (0xFFFF)
+ *      } NamedGroup;
+ *      struct {
+ *          NamedGroup named_group_list<2..2^16-1>;
+ *      } NamedGroupList;
+ *
+ * The "extension_data" field of a supported elliptic curves extension contains
+ * a "NamedCurveList" value (TLS 1.2 RFC 8422):
+ * enum {
+ *      deprecated(1..22),
+ *      secp256r1 (23), secp384r1 (24), secp521r1 (25),
+ *      x25519(29), x448(30),
+ *      reserved (0xFE00..0xFEFF),
+ *      deprecated(0xFF01..0xFF02),
+ *      (0xFFFF)
+ *  } NamedCurve;
+ * struct {
+ *      NamedCurve named_curve_list<2..2^16-1>
+ *  } NamedCurveList;
+ *
+ * The TLS 1.3 supported groups extension was defined to be a compatible
+ * generalization of the TLS 1.2 supported elliptic curves extension. They both
+ * share the same extension identifier.
+ *
+ * DHE groups are not supported yet.
+ */
+int mbedtls_ssl_write_supported_groups_ext( mbedtls_ssl_context *ssl,
+                                            unsigned char *buf,
+                                            const unsigned char *end,
+                                            size_t *out_len )
+{
+    unsigned char *p = buf ;
+    unsigned char *named_group_list; /* Start of named_group_list */
+    size_t named_group_list_len;     /* Length of named_group_list */
+    const uint16_t *group_list = mbedtls_ssl_get_groups( ssl );
+
+    *out_len = 0;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding supported_groups extension" ) );
+
+    /* Check if we have space for header and length fields:
+     * - extension_type            (2 bytes)
+     * - extension_data_length     (2 bytes)
+     * - named_group_list_length   (2 bytes)
+     */
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
+    p += 6;
+
+    named_group_list = p;
+
+    if( group_list == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+
+    for( ; *group_list != 0; group_list++ )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "got supported group(%04x)", *group_list ) );
+
+#if defined(MBEDTLS_ECP_C)
+        if( ( mbedtls_ssl_conf_is_tls13_enabled( ssl->conf ) &&
+              mbedtls_ssl_tls13_named_group_is_ecdhe( *group_list ) ) ||
+            ( mbedtls_ssl_conf_is_tls12_enabled( ssl->conf ) &&
+              mbedtls_ssl_tls12_named_group_is_ecdhe( *group_list ) ) )
+        {
+            const mbedtls_ecp_curve_info *curve_info;
+            curve_info = mbedtls_ecp_curve_info_from_tls_id( *group_list );
+            if( curve_info == NULL )
+                continue;
+            MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+            MBEDTLS_PUT_UINT16_BE( *group_list, p, 0 );
+            p += 2;
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "NamedGroup: %s ( %x )",
+                                curve_info->name, *group_list ) );
+        }
+#endif /* MBEDTLS_ECP_C */
+        /* Add DHE groups here */
+
+    }
+
+    /* Length of named_group_list */
+    named_group_list_len = p - named_group_list;
+    if( named_group_list_len == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "No group available." ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    /* Write extension_type */
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_GROUPS, buf, 0 );
+    /* Write extension_data_length */
+    MBEDTLS_PUT_UINT16_BE( named_group_list_len + 2, buf, 2 );
+    /* Write length of named_group_list */
+    MBEDTLS_PUT_UINT16_BE( named_group_list_len, buf, 4 );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "Supported groups extension",
+                           buf + 4, named_group_list_len + 2 );
+
+    *out_len = p - buf;
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
+    ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
+
+    return( 0 );
+}
+
+#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED ||
+          MBEDTLS_ECDH_C || MBEDTLS_ECDSA_C ||
+          MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
 #endif /* MBEDTLS_SSL_TLS_C */