api/test/fake_frame_decryptor.h

/*
 *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef API_TEST_FAKE_FRAME_DECRYPTOR_H_
#define API_TEST_FAKE_FRAME_DECRYPTOR_H_

#include <stddef.h>
#include <stdint.h>

#include <span>
#include <vector>

#include "api/crypto/frame_decryptor_interface.h"
#include "api/media_types.h"

namespace webrtc {

// The FakeFrameDecryptor is a TEST ONLY fake implementation of the
// FrameDecryptorInterface. It is constructed with a simple single digit key and
// a fixed postfix byte. This is just to validate that the core code works
// as expected.
class FakeFrameDecryptor : public FrameDecryptorInterface {
 public:
  // Provide a key (0,255) and some postfix byte (0,255) this should match the
  // byte you expect from the FakeFrameEncryptor.
  explicit FakeFrameDecryptor(uint8_t fake_key = 0xAA,
                              uint8_t expected_postfix_byte = 255);
  // Fake decryption that just xors the payload with the 1 byte key and checks
  // the postfix byte. This will always fail if fail_decryption_ is set to true.
  Result Decrypt(MediaType media_type,
                 const std::vector<uint32_t>& csrcs,
                 std::span<const uint8_t> additional_data,
                 std::span<const uint8_t> encrypted_frame,
                 std::span<uint8_t> frame) override;
  // Always returns 1 less than the size of the encrypted frame.
  size_t GetMaxPlaintextByteSize(MediaType media_type,
                                 size_t encrypted_frame_size) override;
  // Sets the fake key to use for encryption.
  void SetFakeKey(uint8_t fake_key);
  // Returns the fake key used for encryption.
  uint8_t GetFakeKey() const;
  // Set the Postfix byte that is expected in the encrypted payload.
  void SetExpectedPostfixByte(uint8_t expected_postfix_byte);
  // Returns the postfix byte that will be checked for in the encrypted payload.
  uint8_t GetExpectedPostfixByte() const;
  // If set to true will force all encryption to fail.
  void SetFailDecryption(bool fail_decryption);
  // Simple error codes for tests to validate against.
  enum class FakeDecryptStatus : int {
    OK = 0,
    FORCED_FAILURE = 1,
    INVALID_POSTFIX = 2
  };

 private:
  uint8_t fake_key_ = 0;
  uint8_t expected_postfix_byte_ = 0;
  bool fail_decryption_ = false;
};

}  // namespace webrtc

#endif  // API_TEST_FAKE_FRAME_DECRYPTOR_H_