1 /* 2 * Copyright 2009 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 PC_SRTP_FILTER_H_ 12 #define PC_SRTP_FILTER_H_ 13 14 #include <stddef.h> 15 #include <stdint.h> 16 17 #include <list> 18 #include <map> 19 #include <memory> 20 #include <string> 21 #include <vector> 22 23 #include "absl/types/optional.h" 24 #include "api/array_view.h" 25 #include "api/crypto_params.h" 26 #include "api/jsep.h" 27 #include "api/sequence_checker.h" 28 #include "pc/session_description.h" 29 #include "rtc_base/buffer.h" 30 #include "rtc_base/ssl_stream_adapter.h" 31 32 // Forward declaration to avoid pulling in libsrtp headers here 33 struct srtp_event_data_t; 34 struct srtp_ctx_t_; 35 36 namespace cricket { 37 38 // A helper class used to negotiate SDES crypto params. 39 // TODO(zhihuang): Find a better name for this class, like "SdesNegotiator". 40 class SrtpFilter { 41 public: 42 enum Mode { PROTECT, UNPROTECT }; 43 enum Error { 44 ERROR_NONE, 45 ERROR_FAIL, 46 ERROR_AUTH, 47 ERROR_REPLAY, 48 }; 49 50 SrtpFilter(); 51 ~SrtpFilter(); 52 53 // Whether the filter is active (i.e. crypto has been properly negotiated). 54 bool IsActive() const; 55 56 // Handle the offer/answer negotiation of the crypto parameters internally. 57 // TODO(zhihuang): Make SetOffer/ProvisionalAnswer/Answer private as helper 58 // methods once start using Process. 59 bool Process(const std::vector<CryptoParams>& cryptos, 60 webrtc::SdpType type, 61 ContentSource source); 62 63 // Indicates which crypto algorithms and keys were contained in the offer. 64 // offer_params should contain a list of available parameters to use, or none, 65 // if crypto is not desired. This must be called before SetAnswer. 66 bool SetOffer(const std::vector<CryptoParams>& offer_params, 67 ContentSource source); 68 // Same as SetAnwer. But multiple calls are allowed to SetProvisionalAnswer 69 // after a call to SetOffer. 70 bool SetProvisionalAnswer(const std::vector<CryptoParams>& answer_params, 71 ContentSource source); 72 // Indicates which crypto algorithms and keys were contained in the answer. 73 // answer_params should contain the negotiated parameters, which may be none, 74 // if crypto was not desired or could not be negotiated (and not required). 75 // This must be called after SetOffer. If crypto negotiation completes 76 // successfully, this will advance the filter to the active state. 77 bool SetAnswer(const std::vector<CryptoParams>& answer_params, 78 ContentSource source); 79 80 bool ResetParams(); 81 82 static bool ParseKeyParams(const std::string& params, 83 uint8_t* key, 84 size_t len); 85 send_cipher_suite()86 absl::optional<int> send_cipher_suite() { return send_cipher_suite_; } recv_cipher_suite()87 absl::optional<int> recv_cipher_suite() { return recv_cipher_suite_; } 88 send_key()89 rtc::ArrayView<const uint8_t> send_key() { return send_key_; } recv_key()90 rtc::ArrayView<const uint8_t> recv_key() { return recv_key_; } 91 92 protected: 93 bool ExpectOffer(ContentSource source); 94 95 bool StoreParams(const std::vector<CryptoParams>& params, 96 ContentSource source); 97 98 bool ExpectAnswer(ContentSource source); 99 100 bool DoSetAnswer(const std::vector<CryptoParams>& answer_params, 101 ContentSource source, 102 bool final); 103 104 bool NegotiateParams(const std::vector<CryptoParams>& answer_params, 105 CryptoParams* selected_params); 106 107 private: 108 bool ApplySendParams(const CryptoParams& send_params); 109 110 bool ApplyRecvParams(const CryptoParams& recv_params); 111 112 enum State { 113 ST_INIT, // SRTP filter unused. 114 ST_SENTOFFER, // Offer with SRTP parameters sent. 115 ST_RECEIVEDOFFER, // Offer with SRTP parameters received. 116 ST_SENTPRANSWER_NO_CRYPTO, // Sent provisional answer without crypto. 117 // Received provisional answer without crypto. 118 ST_RECEIVEDPRANSWER_NO_CRYPTO, 119 ST_ACTIVE, // Offer and answer set. 120 // SRTP filter is active but new parameters are offered. 121 // When the answer is set, the state transitions to ST_ACTIVE or ST_INIT. 122 ST_SENTUPDATEDOFFER, 123 // SRTP filter is active but new parameters are received. 124 // When the answer is set, the state transitions back to ST_ACTIVE. 125 ST_RECEIVEDUPDATEDOFFER, 126 // SRTP filter is active but the sent answer is only provisional. 127 // When the final answer is set, the state transitions to ST_ACTIVE or 128 // ST_INIT. 129 ST_SENTPRANSWER, 130 // SRTP filter is active but the received answer is only provisional. 131 // When the final answer is set, the state transitions to ST_ACTIVE or 132 // ST_INIT. 133 ST_RECEIVEDPRANSWER 134 }; 135 State state_ = ST_INIT; 136 std::vector<CryptoParams> offer_params_; 137 CryptoParams applied_send_params_; 138 CryptoParams applied_recv_params_; 139 absl::optional<int> send_cipher_suite_; 140 absl::optional<int> recv_cipher_suite_; 141 rtc::ZeroOnFreeBuffer<uint8_t> send_key_; 142 rtc::ZeroOnFreeBuffer<uint8_t> recv_key_; 143 }; 144 145 } // namespace cricket 146 147 #endif // PC_SRTP_FILTER_H_ 148