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