105 lines
4.4 KiB
C
105 lines
4.4 KiB
C
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/*
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* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef VIDEO_BUFFERED_FRAME_DECRYPTOR_H_
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#define VIDEO_BUFFERED_FRAME_DECRYPTOR_H_
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#include <deque>
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#include <memory>
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#include "api/crypto/crypto_options.h"
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#include "api/crypto/frame_decryptor_interface.h"
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#include "modules/video_coding/frame_object.h"
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namespace webrtc {
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// This callback is provided during the construction of the
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// BufferedFrameDecryptor and is called each time a frame is sucessfully
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// decrypted by the buffer.
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class OnDecryptedFrameCallback {
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public:
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virtual ~OnDecryptedFrameCallback() = default;
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// Called each time a decrypted frame is returned.
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virtual void OnDecryptedFrame(
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std::unique_ptr<video_coding::RtpFrameObject> frame) = 0;
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};
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// This callback is called each time there is a status change in the decryption
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// stream. For example going from a none state to a first decryption or going
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// frome a decryptable state to a non decryptable state.
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class OnDecryptionStatusChangeCallback {
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public:
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virtual ~OnDecryptionStatusChangeCallback() = default;
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// Called each time the decryption stream status changes. This call is
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// blocking so the caller must relinquish the callback quickly. This status
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// must match what is specified in the FrameDecryptorInterface file. Notably
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// 0 must indicate success and any positive integer is a failure.
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virtual void OnDecryptionStatusChange(
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FrameDecryptorInterface::Status status) = 0;
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};
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// The BufferedFrameDecryptor is responsible for deciding when to pass
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// decrypted received frames onto the OnDecryptedFrameCallback. Frames can be
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// delayed when frame encryption is enabled but the key hasn't arrived yet. In
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// this case we stash about 1 second of encrypted frames instead of dropping
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// them to prevent re-requesting the key frame. This optimization is
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// particularly important on low bandwidth networks. Note stashing is only ever
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// done if we have never sucessfully decrypted a frame before. After the first
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// successful decryption payloads will never be stashed.
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class BufferedFrameDecryptor final {
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public:
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// Constructs a new BufferedFrameDecryptor that can hold
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explicit BufferedFrameDecryptor(
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OnDecryptedFrameCallback* decrypted_frame_callback,
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OnDecryptionStatusChangeCallback* decryption_status_change_callback);
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~BufferedFrameDecryptor();
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// This object cannot be copied.
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BufferedFrameDecryptor(const BufferedFrameDecryptor&) = delete;
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BufferedFrameDecryptor& operator=(const BufferedFrameDecryptor&) = delete;
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// Sets a new frame decryptor as the decryptor for the buffered frame
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// decryptor. This allows the decryptor to be switched out without resetting
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// the video stream.
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void SetFrameDecryptor(
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rtc::scoped_refptr<FrameDecryptorInterface> frame_decryptor);
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// Determines whether the frame should be stashed, dropped or handed off to
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// the OnDecryptedFrameCallback.
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void ManageEncryptedFrame(
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std::unique_ptr<video_coding::RtpFrameObject> encrypted_frame);
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private:
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// Represents what should be done with a given frame.
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enum class FrameDecision { kStash, kDecrypted, kDrop };
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// Attempts to decrypt the frame, if it fails and no prior frames have been
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// decrypted it will return kStash. Otherwise fail to decrypts will return
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// kDrop. Successful decryptions will always return kDecrypted.
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FrameDecision DecryptFrame(video_coding::RtpFrameObject* frame);
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// Retries all the stashed frames this is triggered each time a kDecrypted
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// event occurs.
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void RetryStashedFrames();
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static const size_t kMaxStashedFrames = 24;
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const bool generic_descriptor_auth_experiment_;
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bool first_frame_decrypted_ = false;
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FrameDecryptorInterface::Status last_status_ =
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FrameDecryptorInterface::Status::kUnknown;
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rtc::scoped_refptr<FrameDecryptorInterface> frame_decryptor_;
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OnDecryptedFrameCallback* const decrypted_frame_callback_;
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OnDecryptionStatusChangeCallback* const decryption_status_change_callback_;
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std::deque<std::unique_ptr<video_coding::RtpFrameObject>> stashed_frames_;
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};
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} // namespace webrtc
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#endif // VIDEO_BUFFERED_FRAME_DECRYPTOR_H_
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