text: /*
   * libjingle
   * Copyright 2014 Google Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *  1. Redistributions of source code must retain the above copyright notice,
   *     this list of conditions and the following disclaimer.
   *  2. Redistributions in binary form must reproduce the above copyright notice,
   *     this list of conditions and the following disclaimer in the documentation
   *     and/or other materials provided with the distribution.
   *  3. The name of the author may not be used to endorse or promote products
   *     derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
   * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #if defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
  
  #include "talk/session/media/externalhmac.h"
  
  #include <stdlib.h>  // For malloc/free.
  
  #ifdef SRTP_RELATIVE_PATH
  #include "srtp.h"  // NOLINT
  #else
  #include "third_party/libsrtp/include/srtp.h"
  #endif  // SRTP_RELATIVE_PATH
  
  #include "webrtc/base/logging.h"
  
  // Begin test case 0 */
  static const uint8_t kExternalHmacTestCase0Key[20] = {
    0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
    0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
    0x0b, 0x0b, 0x0b, 0x0b
  };
  
  static const uint8_t kExternalHmacTestCase0Data[8] = {
    0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65   // "Hi There"
  };
  
  static const uint8_t kExternalHmacFakeTag[10] = {
    0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd
  };
  
  static const auth_test_case_t kExternalHmacTestCase0 = {
    20,                                                    // Octets in key
    const_cast<uint8_t*>(kExternalHmacTestCase0Key),   // Key
    8,                                                     // Octets in data
    const_cast<uint8_t*>(kExternalHmacTestCase0Data),  // Data
    10,                                                    // Octets in tag
    const_cast<uint8_t*>(kExternalHmacFakeTag),          // Tag
    NULL                                                   // Pointer to next
                                                           // testcase
  };
  
  static const char kExternalHmacDescription[] =
      "external hmac sha-1 authentication";
  
  // auth_type_t external_hmac is the hmac metaobject
  
  static const auth_type_t external_hmac  = {
    external_hmac_alloc,
    external_hmac_dealloc,
    (auth_init_func)    external_hmac_init,
    (auth_compute_func) external_hmac_compute,
    (auth_update_func)  external_hmac_update,
    (auth_start_func)   external_hmac_start,
    const_cast<char*>(kExternalHmacDescription),
    0,     // Instance count.
    const_cast<auth_test_case_t*>(&kExternalHmacTestCase0),
    NULL,  // No debugging module.
    EXTERNAL_HMAC_SHA1
  };
  
  
  err_status_t external_hmac_alloc(auth_t** a, int key_len, int out_len) {
    uint8_t* pointer;
  
    // Check key length - note that we don't support keys larger
    // than 20 bytes yet
    if (key_len > 20)
      return err_status_bad_param;
  
    // Check output length - should be less than 20 bytes/
    if (out_len > 20)
      return err_status_bad_param;
  
    // Allocate memory for auth and hmac_ctx_t structures.
    pointer = new uint8_t[(sizeof(external_hmac_ctx_t) + sizeof(auth_t))];
    if (pointer == NULL)
      return err_status_alloc_fail;
  
    // Set pointers
    *a = (auth_t *)pointer;
    // |external_hmac| is const and libsrtp expects |type| to be non-const.
    // const conversion is required. |external_hmac| is constant because we don't
    // want to increase global count in Chrome.
    (*a)->type = const_cast<auth_type_t*>(&external_hmac);
    (*a)->state = pointer + sizeof(auth_t);
    (*a)->out_len = out_len;
    (*a)->key_len = key_len;
    (*a)->prefix_len = 0;
  
    return err_status_ok;
  }
  
  err_status_t external_hmac_dealloc(auth_t* a) {
    // Zeroize entire state
    memset((uint8_t *)a, 0, sizeof(external_hmac_ctx_t) + sizeof(auth_t));
  
    // Free memory
    delete[] a;
  
    return err_status_ok;
  }
  
  err_status_t external_hmac_init(external_hmac_ctx_t* state,
                                  const uint8_t* key,
                                  int key_len) {
    if (key_len > HMAC_KEY_LENGTH)
      return err_status_bad_param;
  
    memset(state->key, 0, key_len);
    memcpy(state->key, key, key_len);
    state->key_length = key_len;
    return err_status_ok;
  }
  
  err_status_t external_hmac_start(external_hmac_ctx_t* state) {
    return err_status_ok;
  }
  
  err_status_t external_hmac_update(external_hmac_ctx_t* state,
                                    const uint8_t* message,
                                    int msg_octets) {
    return err_status_ok;
  }
  
  err_status_t external_hmac_compute(external_hmac_ctx_t* state,
                                     const void* message,
                                     int msg_octets,
                                     int tag_len,
                                     uint8_t* result) {
    memcpy(result, kExternalHmacFakeTag, tag_len);
    return err_status_ok;
  }
  
  err_status_t external_crypto_init() {
    // |external_hmac| is const. const_cast is required as libsrtp expects
    // non-const.
    err_status_t status = crypto_kernel_replace_auth_type(
        const_cast<auth_type_t*>(&external_hmac), EXTERNAL_HMAC_SHA1);
    if (status) {
      LOG(LS_ERROR) << "Error in replacing default auth module, error: "
                    << status;
      return err_status_fail;
    }
    return err_status_ok;
  }
  
  #endif  // defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
  