1 /* 2 * Copyright 2018 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef API_CRYPTO_FRAME_DECRYPTOR_INTERFACE_H_ 12 #define API_CRYPTO_FRAME_DECRYPTOR_INTERFACE_H_ 13 14 #include <vector> 15 16 #include "api/array_view.h" 17 #include "api/media_types.h" 18 #include "rtc_base/ref_count.h" 19 20 namespace webrtc { 21 22 // FrameDecryptorInterface allows users to provide a custom decryption 23 // implementation for all incoming audio and video frames. The user must also 24 // provide a FrameEncryptorInterface to be able to encrypt the frames being 25 // sent out of the device. Note this is an additional layer of encyrption in 26 // addition to the standard SRTP mechanism and is not intended to be used 27 // without it. You may assume that this interface will have the same lifetime 28 // as the RTPReceiver it is attached to. It must only be attached to one 29 // RTPReceiver. Additional data may be null. 30 class FrameDecryptorInterface : public rtc::RefCountInterface { 31 public: 32 // The Status enum represents all possible states that can be 33 // returned when attempting to decrypt a frame. kRecoverable indicates that 34 // there was an error with the given frame and so it should not be passed to 35 // the decoder, however it hints that the receive stream is still decryptable 36 // which is important for determining when to send key frame requests 37 // kUnknown should never be returned by the implementor. 38 enum class Status { kOk, kRecoverable, kFailedToDecrypt, kUnknown }; 39 40 struct Result { ResultResult41 Result(Status status, size_t bytes_written) 42 : status(status), bytes_written(bytes_written) {} 43 IsOkResult44 bool IsOk() const { return status == Status::kOk; } 45 46 const Status status; 47 const size_t bytes_written; 48 }; 49 ~FrameDecryptorInterface()50 ~FrameDecryptorInterface() override {} 51 52 // Attempts to decrypt the encrypted frame. You may assume the frame size will 53 // be allocated to the size returned from GetMaxPlaintextSize. You may assume 54 // that the frames are in order if SRTP is enabled. The stream is not provided 55 // here and it is up to the implementor to transport this information to the 56 // receiver if they care about it. You must set bytes_written to how many 57 // bytes you wrote to in the frame buffer. kOk must be returned if successful, 58 // kRecoverable should be returned if the failure was due to something other 59 // than a decryption failure. kFailedToDecrypt should be returned in all other 60 // cases. 61 virtual Result Decrypt(cricket::MediaType media_type, 62 const std::vector<uint32_t>& csrcs, 63 rtc::ArrayView<const uint8_t> additional_data, 64 rtc::ArrayView<const uint8_t> encrypted_frame, 65 rtc::ArrayView<uint8_t> frame) = 0; 66 67 // Returns the total required length in bytes for the output of the 68 // decryption. This can be larger than the actual number of bytes you need but 69 // must never be smaller as it informs the size of the frame buffer. 70 virtual size_t GetMaxPlaintextByteSize(cricket::MediaType media_type, 71 size_t encrypted_frame_size) = 0; 72 }; 73 74 } // namespace webrtc 75 76 #endif // API_CRYPTO_FRAME_DECRYPTOR_INTERFACE_H_ 77