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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_pq_kem.h"
      17                 :            : 
      18                 :            : #include <stdint.h>
      19                 :            : 
      20                 :            : #include "crypto/s2n_pq.h"
      21                 :            : #include "tls/s2n_kem.h"
      22                 :            : #include "tls/s2n_security_policies.h"
      23                 :            : #include "tls/s2n_tls.h"
      24                 :            : #include "tls/s2n_tls_parameters.h"
      25                 :            : #include "utils/s2n_safety.h"
      26                 :            : 
      27                 :            : static bool s2n_client_pq_kem_should_send(struct s2n_connection *conn);
      28                 :            : static int s2n_client_pq_kem_send(struct s2n_connection *conn, struct s2n_stuffer *out);
      29                 :            : static int s2n_client_pq_kem_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
      30                 :            : 
      31                 :            : const s2n_extension_type s2n_client_pq_kem_extension = {
      32                 :            :     .iana_value = TLS_EXTENSION_PQ_KEM_PARAMETERS,
      33                 :            :     .is_response = false,
      34                 :            :     .send = s2n_client_pq_kem_send,
      35                 :            :     .recv = s2n_client_pq_kem_recv,
      36                 :            :     .should_send = s2n_client_pq_kem_should_send,
      37                 :            :     .if_missing = s2n_extension_noop_if_missing,
      38                 :            : };
      39                 :            : 
      40                 :            : static bool s2n_client_pq_kem_should_send(struct s2n_connection *conn)
      41                 :       7721 : {
      42                 :       7721 :     const struct s2n_security_policy *security_policy = NULL;
      43         [ +  - ]:       7721 :     return s2n_connection_get_security_policy(conn, &security_policy) == S2N_SUCCESS
      44         [ -  + ]:       7721 :             && s2n_pq_kem_is_extension_required(security_policy)
      45         [ #  # ]:       7721 :             && s2n_pq_is_enabled();
      46                 :       7721 : }
      47                 :            : 
      48                 :            : static int s2n_client_pq_kem_send(struct s2n_connection *conn, struct s2n_stuffer *out)
      49                 :          0 : {
      50                 :          0 :     const struct s2n_kem_preferences *kem_preferences = NULL;
      51         [ #  # ]:          0 :     POSIX_GUARD(s2n_connection_get_kem_preferences(conn, &kem_preferences));
      52 [ #  # ][ #  # ]:          0 :     POSIX_ENSURE_REF(kem_preferences);
      53                 :            : 
      54         [ #  # ]:          0 :     POSIX_GUARD(s2n_stuffer_write_uint16(out, kem_preferences->kem_count * sizeof(kem_extension_size)));
      55         [ #  # ]:          0 :     for (int i = 0; i < kem_preferences->kem_count; i++) {
      56         [ #  # ]:          0 :         POSIX_GUARD(s2n_stuffer_write_uint16(out, kem_preferences->kems[i]->kem_extension_id));
      57                 :          0 :     }
      58                 :            : 
      59                 :          0 :     return S2N_SUCCESS;
      60                 :          0 : }
      61                 :            : 
      62                 :            : static int s2n_client_pq_kem_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
      63                 :          1 : {
      64                 :          1 :     uint16_t size_of_all = 0;
      65                 :          1 :     struct s2n_blob *proposed_kems = &conn->kex_params.client_pq_kem_extension;
      66                 :            : 
      67                 :            :     /* Ignore extension if PQ is disabled */
      68         [ +  - ]:          1 :     if (!s2n_pq_is_enabled()) {
      69                 :          1 :         return S2N_SUCCESS;
      70                 :          1 :     }
      71                 :            : 
      72         [ #  # ]:          0 :     POSIX_GUARD(s2n_stuffer_read_uint16(extension, &size_of_all));
      73 [ #  # ][ #  # ]:          0 :     if (size_of_all > s2n_stuffer_data_available(extension) || size_of_all % sizeof(kem_extension_size)) {
      74                 :            :         /* Malformed length, ignore the extension */
      75                 :          0 :         return S2N_SUCCESS;
      76                 :          0 :     }
      77                 :            : 
      78                 :          0 :     proposed_kems->size = size_of_all;
      79                 :          0 :     proposed_kems->data = s2n_stuffer_raw_read(extension, proposed_kems->size);
      80 [ #  # ][ #  # ]:          0 :     POSIX_ENSURE_REF(proposed_kems->data);
      81                 :            : 
      82                 :          0 :     return S2N_SUCCESS;
      83                 :          0 : }