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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                 :            : #include <sys/param.h>
      20                 :            : 
      21                 :            : #include "crypto/s2n_pq.h"
      22                 :            : #include "tls/s2n_kem.h"
      23                 :            : #include "tls/s2n_security_policies.h"
      24                 :            : #include "tls/s2n_tls.h"
      25                 :            : #include "tls/s2n_tls_parameters.h"
      26                 :            : #include "utils/s2n_safety.h"
      27                 :            : 
      28                 :            : static bool s2n_client_pq_kem_should_send(struct s2n_connection *conn);
      29                 :            : static int s2n_client_pq_kem_send(struct s2n_connection *conn, struct s2n_stuffer *out);
      30                 :            : static int s2n_client_pq_kem_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
      31                 :            : 
      32                 :            : const s2n_extension_type s2n_client_pq_kem_extension = {
      33                 :            :     .iana_value = TLS_EXTENSION_PQ_KEM_PARAMETERS,
      34                 :            :     .is_response = false,
      35                 :            :     .send = s2n_client_pq_kem_send,
      36                 :            :     .recv = s2n_client_pq_kem_recv,
      37                 :            :     .should_send = s2n_client_pq_kem_should_send,
      38                 :            :     .if_missing = s2n_extension_noop_if_missing,
      39                 :            : };
      40                 :            : 
      41                 :            : static bool s2n_client_pq_kem_should_send(struct s2n_connection *conn)
      42                 :       7352 : {
      43                 :       7352 :     const struct s2n_security_policy *security_policy = NULL;
      44         [ +  - ]:       7352 :     return s2n_connection_get_security_policy(conn, &security_policy) == S2N_SUCCESS
      45         [ -  + ]:       7352 :             && s2n_pq_kem_is_extension_required(security_policy)
      46         [ #  # ]:       7352 :             && s2n_pq_is_enabled();
      47                 :       7352 : }
      48                 :            : 
      49                 :            : static int s2n_client_pq_kem_send(struct s2n_connection *conn, struct s2n_stuffer *out)
      50                 :          0 : {
      51                 :          0 :     const struct s2n_kem_preferences *kem_preferences = NULL;
      52         [ #  # ]:          0 :     POSIX_GUARD(s2n_connection_get_kem_preferences(conn, &kem_preferences));
      53 [ #  # ][ #  # ]:          0 :     POSIX_ENSURE_REF(kem_preferences);
      54                 :            : 
      55         [ #  # ]:          0 :     POSIX_GUARD(s2n_stuffer_write_uint16(out, kem_preferences->kem_count * sizeof(kem_extension_size)));
      56         [ #  # ]:          0 :     for (int i = 0; i < kem_preferences->kem_count; i++) {
      57         [ #  # ]:          0 :         POSIX_GUARD(s2n_stuffer_write_uint16(out, kem_preferences->kems[i]->kem_extension_id));
      58                 :          0 :     }
      59                 :            : 
      60                 :          0 :     return S2N_SUCCESS;
      61                 :          0 : }
      62                 :            : 
      63                 :            : static int s2n_client_pq_kem_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
      64                 :          1 : {
      65                 :          1 :     uint16_t size_of_all = 0;
      66                 :          1 :     struct s2n_blob *proposed_kems = &conn->kex_params.client_pq_kem_extension;
      67                 :            : 
      68                 :            :     /* Ignore extension if PQ is disabled */
      69         [ +  - ]:          1 :     if (!s2n_pq_is_enabled()) {
      70                 :          1 :         return S2N_SUCCESS;
      71                 :          1 :     }
      72                 :            : 
      73         [ #  # ]:          0 :     POSIX_GUARD(s2n_stuffer_read_uint16(extension, &size_of_all));
      74 [ #  # ][ #  # ]:          0 :     if (size_of_all > s2n_stuffer_data_available(extension) || size_of_all % sizeof(kem_extension_size)) {
      75                 :            :         /* Malformed length, ignore the extension */
      76                 :          0 :         return S2N_SUCCESS;
      77                 :          0 :     }
      78                 :            : 
      79                 :          0 :     proposed_kems->size = size_of_all;
      80                 :          0 :     proposed_kems->data = s2n_stuffer_raw_read(extension, proposed_kems->size);
      81 [ #  # ][ #  # ]:          0 :     POSIX_ENSURE_REF(proposed_kems->data);
      82                 :            : 
      83                 :          0 :     return S2N_SUCCESS;
      84                 :          0 : }