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       1                 :            : /*
       2                 :            :  * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
       3                 :            :  *
       4                 :            :  * Licensed under the Apache License, Version 2.0 (the "License").
       5                 :            :  * You may not use this file except in compliance with the License.
       6                 :            :  * A copy of the License is located at
       7                 :            :  *
       8                 :            :  *  http://aws.amazon.com/apache2.0
       9                 :            :  *
      10                 :            :  * or in the "license" file accompanying this file. This file is distributed
      11                 :            :  * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
      12                 :            :  * express or implied. See the License for the specific language governing
      13                 :            :  * permissions and limitations under the License.
      14                 :            :  */
      15                 :            : 
      16                 :            : #include "tls/extensions/s2n_client_alpn.h"
      17                 :            : 
      18                 :            : #include <stdint.h>
      19                 :            : #include <sys/param.h>
      20                 :            : 
      21                 :            : #include "tls/extensions/s2n_extension_type.h"
      22                 :            : #include "tls/s2n_protocol_preferences.h"
      23                 :            : #include "tls/s2n_tls.h"
      24                 :            : #include "tls/s2n_tls_parameters.h"
      25                 :            : #include "utils/s2n_safety.h"
      26                 :            : 
      27                 :            : bool s2n_client_alpn_should_send(struct s2n_connection *conn);
      28                 :            : static int s2n_client_alpn_send(struct s2n_connection *conn, struct s2n_stuffer *out);
      29                 :            : static int s2n_client_alpn_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
      30                 :            : 
      31                 :            : const s2n_extension_type s2n_client_alpn_extension = {
      32                 :            :     .iana_value = TLS_EXTENSION_ALPN,
      33                 :            :     .is_response = false,
      34                 :            :     .send = s2n_client_alpn_send,
      35                 :            :     .recv = s2n_client_alpn_recv,
      36                 :            :     .should_send = s2n_client_alpn_should_send,
      37                 :            :     .if_missing = s2n_extension_noop_if_missing,
      38                 :            : };
      39                 :            : 
      40                 :            : bool s2n_client_alpn_should_send(struct s2n_connection *conn)
      41                 :      14726 : {
      42                 :      14726 :     struct s2n_blob *client_app_protocols = NULL;
      43                 :            : 
      44         [ +  + ]:      14726 :     return s2n_connection_get_protocol_preferences(conn, &client_app_protocols) == S2N_SUCCESS
      45 [ +  + ][ +  - ]:      14726 :             && client_app_protocols->size != 0 && client_app_protocols->data != NULL;
      46                 :      14726 : }
      47                 :            : 
      48                 :            : static int s2n_client_alpn_send(struct s2n_connection *conn, struct s2n_stuffer *out)
      49                 :         24 : {
      50                 :         24 :     struct s2n_blob *client_app_protocols = NULL;
      51         [ -  + ]:         24 :     POSIX_GUARD(s2n_connection_get_protocol_preferences(conn, &client_app_protocols));
      52 [ #  # ][ -  + ]:         24 :     POSIX_ENSURE_REF(client_app_protocols);
      53                 :            : 
      54         [ -  + ]:         24 :     POSIX_GUARD(s2n_stuffer_write_uint16(out, client_app_protocols->size));
      55         [ -  + ]:         24 :     POSIX_GUARD(s2n_stuffer_write(out, client_app_protocols));
      56                 :            : 
      57                 :         24 :     return S2N_SUCCESS;
      58                 :         24 : }
      59                 :            : 
      60                 :            : static int s2n_client_alpn_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
      61                 :         50 : {
      62                 :         50 :     struct s2n_blob *supported_protocols = NULL;
      63         [ -  + ]:         50 :     POSIX_GUARD(s2n_connection_get_protocol_preferences(conn, &supported_protocols));
      64 [ -  + ][ #  # ]:         50 :     POSIX_ENSURE_REF(supported_protocols);
      65                 :            : 
      66         [ +  + ]:         50 :     if (supported_protocols->size == 0) {
      67                 :            :         /* No protocols configured, nothing to do */
      68                 :         16 :         return S2N_SUCCESS;
      69                 :         16 :     }
      70                 :            : 
      71                 :         34 :     uint16_t wire_size = 0;
      72         [ -  + ]:         34 :     POSIX_GUARD(s2n_stuffer_read_uint16(extension, &wire_size));
      73 [ -  + ][ +  + ]:         34 :     if (wire_size > s2n_stuffer_data_available(extension) || wire_size < 3) {
      74                 :            :         /* Malformed length, ignore the extension */
      75                 :          2 :         return S2N_SUCCESS;
      76                 :          2 :     }
      77                 :            : 
      78                 :         32 :     struct s2n_blob client_protocols = { 0 };
      79         [ -  + ]:         32 :     POSIX_GUARD(s2n_blob_init(&client_protocols, s2n_stuffer_raw_read(extension, wire_size), wire_size));
      80                 :            : 
      81                 :         32 :     struct s2n_stuffer server_protocols = { 0 };
      82         [ -  + ]:         32 :     POSIX_GUARD(s2n_stuffer_init(&server_protocols, supported_protocols));
      83         [ -  + ]:         32 :     POSIX_GUARD(s2n_stuffer_skip_write(&server_protocols, supported_protocols->size));
      84                 :            : 
      85         [ -  + ]:         32 :     POSIX_GUARD_RESULT(s2n_select_server_preference_protocol(conn, &server_protocols, &client_protocols));
      86                 :            : 
      87                 :         32 :     return S2N_SUCCESS;
      88                 :         32 : }