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/*
* 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_CRYPTO_FRAME_DECRYPTOR_INTERFACE_H_
#define API_CRYPTO_FRAME_DECRYPTOR_INTERFACE_H_
#include <cstddef>
#include <cstdint>
#include <vector>
#include "api/array_view.h"
#include "api/media_types.h"
#include "api/ref_count.h"
namespace webrtc {
// FrameDecryptorInterface allows users to provide a custom decryption
// implementation for all incoming audio and video frames. The user must also
// provide a FrameEncryptorInterface to be able to encrypt the frames being
// sent out of the device. Note this is an additional layer of encyrption in
// addition to the standard SRTP mechanism and is not intended to be used
// without it. You may assume that this interface will have the same lifetime
// as the RTPReceiver it is attached to. It must only be attached to one
// RTPReceiver. Additional data may be null.
class FrameDecryptorInterface : public RefCountInterface {
public:
// The Status enum represents all possible states that can be
// returned when attempting to decrypt a frame. kRecoverable indicates that
// there was an error with the given frame and so it should not be passed to
// the decoder, however it hints that the receive stream is still decryptable
// which is important for determining when to send key frame requests
// kUnknown should never be returned by the implementor.
enum class Status { kOk, kRecoverable, kFailedToDecrypt, kUnknown };
struct Result {
Result(Status status, size_t bytes_written)
: status(status), bytes_written(bytes_written) {}
bool IsOk() const { return status == Status::kOk; }
const Status status;
const size_t bytes_written;
};
~FrameDecryptorInterface() override {}
// Attempts to decrypt the encrypted frame. You may assume the frame size will
// be allocated to the size returned from GetMaxPlaintextSize. You may assume
// that the frames are in order if SRTP is enabled. The stream is not provided
// here and it is up to the implementor to transport this information to the
// receiver if they care about it. You must set bytes_written to how many
// bytes you wrote to in the frame buffer. kOk must be returned if successful,
// kRecoverable should be returned if the failure was due to something other
// than a decryption failure. kFailedToDecrypt should be returned in all other
// cases.
virtual Result Decrypt(MediaType media_type,
const std::vector<uint32_t>& csrcs,
ArrayView<const uint8_t> additional_data,
ArrayView<const uint8_t> encrypted_frame,
ArrayView<uint8_t> frame) = 0;
// Returns the total required length in bytes for the output of the
// decryption. This can be larger than the actual number of bytes you need but
// must never be smaller as it informs the size of the frame buffer.
virtual size_t GetMaxPlaintextByteSize(MediaType media_type,
size_t encrypted_frame_size) = 0;
};
} // namespace webrtc
#endif // API_CRYPTO_FRAME_DECRYPTOR_INTERFACE_H_
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