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/*
* Copyright 2009 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 WEBRTC_PC_SRTPFILTER_H_
#define WEBRTC_PC_SRTPFILTER_H_
#include <list>
#include <map>
#include <memory>
#include <string>
#include <vector>
#include "webrtc/base/basictypes.h"
#include "webrtc/base/constructormagic.h"
#include "webrtc/base/criticalsection.h"
#include "webrtc/base/sigslotrepeater.h"
#include "webrtc/base/sslstreamadapter.h"
#include "webrtc/base/thread_checker.h"
#include "webrtc/media/base/cryptoparams.h"
#include "webrtc/p2p/base/sessiondescription.h"
// Forward declaration to avoid pulling in libsrtp headers here
struct srtp_event_data_t;
struct srtp_ctx_t;
struct srtp_policy_t;
namespace cricket {
class SrtpSession;
class SrtpStat;
void EnableSrtpDebugging();
void ShutdownSrtp();
// Class to transform SRTP to/from RTP.
// Initialize by calling SetSend with the local security params, then call
// SetRecv once the remote security params are received. At that point
// Protect/UnprotectRt(c)p can be called to encrypt/decrypt data.
// TODO: Figure out concurrency policy for SrtpFilter.
class SrtpFilter {
public:
enum Mode {
PROTECT,
UNPROTECT
};
enum Error {
ERROR_NONE,
ERROR_FAIL,
ERROR_AUTH,
ERROR_REPLAY,
};
SrtpFilter();
~SrtpFilter();
// Whether the filter is active (i.e. crypto has been properly negotiated).
bool IsActive() const;
// Indicates which crypto algorithms and keys were contained in the offer.
// offer_params should contain a list of available parameters to use, or none,
// if crypto is not desired. This must be called before SetAnswer.
bool SetOffer(const std::vector<CryptoParams>& offer_params,
ContentSource source);
// Same as SetAnwer. But multiple calls are allowed to SetProvisionalAnswer
// after a call to SetOffer.
bool SetProvisionalAnswer(const std::vector<CryptoParams>& answer_params,
ContentSource source);
// Indicates which crypto algorithms and keys were contained in the answer.
// answer_params should contain the negotiated parameters, which may be none,
// if crypto was not desired or could not be negotiated (and not required).
// This must be called after SetOffer. If crypto negotiation completes
// successfully, this will advance the filter to the active state.
bool SetAnswer(const std::vector<CryptoParams>& answer_params,
ContentSource source);
// Just set up both sets of keys directly.
// Used with DTLS-SRTP.
bool SetRtpParams(int send_cs,
const uint8_t* send_key,
int send_key_len,
int recv_cs,
const uint8_t* recv_key,
int recv_key_len);
bool SetRtcpParams(int send_cs,
const uint8_t* send_key,
int send_key_len,
int recv_cs,
const uint8_t* recv_key,
int recv_key_len);
// Encrypts/signs an individual RTP/RTCP packet, in-place.
// If an HMAC is used, this will increase the packet size.
bool ProtectRtp(void* data, int in_len, int max_len, int* out_len);
// Overloaded version, outputs packet index.
bool ProtectRtp(void* data,
int in_len,
int max_len,
int* out_len,
int64_t* index);
bool ProtectRtcp(void* data, int in_len, int max_len, int* out_len);
// Decrypts/verifies an invidiual RTP/RTCP packet.
// If an HMAC is used, this will decrease the packet size.
bool UnprotectRtp(void* data, int in_len, int* out_len);
bool UnprotectRtcp(void* data, int in_len, int* out_len);
// Returns rtp auth params from srtp context.
bool GetRtpAuthParams(uint8_t** key, int* key_len, int* tag_len);
// Update the silent threshold (in ms) for signaling errors.
void set_signal_silent_time(int signal_silent_time_in_ms);
bool ResetParams();
sigslot::repeater3<uint32_t, Mode, Error> SignalSrtpError;
protected:
bool ExpectOffer(ContentSource source);
bool StoreParams(const std::vector<CryptoParams>& params,
ContentSource source);
bool ExpectAnswer(ContentSource source);
bool DoSetAnswer(const std::vector<CryptoParams>& answer_params,
ContentSource source,
bool final);
void CreateSrtpSessions();
bool NegotiateParams(const std::vector<CryptoParams>& answer_params,
CryptoParams* selected_params);
bool ApplyParams(const CryptoParams& send_params,
const CryptoParams& recv_params);
static bool ParseKeyParams(const std::string& params,
uint8_t* key,
size_t len);
private:
enum State {
ST_INIT, // SRTP filter unused.
ST_SENTOFFER, // Offer with SRTP parameters sent.
ST_RECEIVEDOFFER, // Offer with SRTP parameters received.
ST_SENTPRANSWER_NO_CRYPTO, // Sent provisional answer without crypto.
// Received provisional answer without crypto.
ST_RECEIVEDPRANSWER_NO_CRYPTO,
ST_ACTIVE, // Offer and answer set.
// SRTP filter is active but new parameters are offered.
// When the answer is set, the state transitions to ST_ACTIVE or ST_INIT.
ST_SENTUPDATEDOFFER,
// SRTP filter is active but new parameters are received.
// When the answer is set, the state transitions back to ST_ACTIVE.
ST_RECEIVEDUPDATEDOFFER,
// SRTP filter is active but the sent answer is only provisional.
// When the final answer is set, the state transitions to ST_ACTIVE or
// ST_INIT.
ST_SENTPRANSWER,
// SRTP filter is active but the received answer is only provisional.
// When the final answer is set, the state transitions to ST_ACTIVE or
// ST_INIT.
ST_RECEIVEDPRANSWER
};
State state_;
int signal_silent_time_in_ms_;
std::vector<CryptoParams> offer_params_;
std::unique_ptr<SrtpSession> send_session_;
std::unique_ptr<SrtpSession> recv_session_;
std::unique_ptr<SrtpSession> send_rtcp_session_;
std::unique_ptr<SrtpSession> recv_rtcp_session_;
CryptoParams applied_send_params_;
CryptoParams applied_recv_params_;
};
// Class that wraps a libSRTP session.
class SrtpSession {
public:
SrtpSession();
~SrtpSession();
// Configures the session for sending data using the specified
// cipher-suite and key. Receiving must be done by a separate session.
bool SetSend(int cs, const uint8_t* key, size_t len);
// Configures the session for receiving data using the specified
// cipher-suite and key. Sending must be done by a separate session.
bool SetRecv(int cs, const uint8_t* key, size_t len);
// Encrypts/signs an individual RTP/RTCP packet, in-place.
// If an HMAC is used, this will increase the packet size.
bool ProtectRtp(void* data, int in_len, int max_len, int* out_len);
// Overloaded version, outputs packet index.
bool ProtectRtp(void* data,
int in_len,
int max_len,
int* out_len,
int64_t* index);
bool ProtectRtcp(void* data, int in_len, int max_len, int* out_len);
// Decrypts/verifies an invidiual RTP/RTCP packet.
// If an HMAC is used, this will decrease the packet size.
bool UnprotectRtp(void* data, int in_len, int* out_len);
bool UnprotectRtcp(void* data, int in_len, int* out_len);
// Helper method to get authentication params.
bool GetRtpAuthParams(uint8_t** key, int* key_len, int* tag_len);
// Update the silent threshold (in ms) for signaling errors.
void set_signal_silent_time(int signal_silent_time_in_ms);
// Calls srtp_shutdown if it's initialized.
static void Terminate();
sigslot::repeater3<uint32_t, SrtpFilter::Mode, SrtpFilter::Error>
SignalSrtpError;
private:
bool SetKey(int type, int cs, const uint8_t* key, size_t len);
// Returns send stream current packet index from srtp db.
bool GetSendStreamPacketIndex(void* data, int in_len, int64_t* index);
static bool Init();
void HandleEvent(const srtp_event_data_t* ev);
static void HandleEventThunk(srtp_event_data_t* ev);
rtc::ThreadChecker thread_checker_;
srtp_ctx_t* session_;
int rtp_auth_tag_len_;
int rtcp_auth_tag_len_;
std::unique_ptr<SrtpStat> srtp_stat_;
static bool inited_;
static rtc::GlobalLockPod lock_;
int last_send_seq_num_;
RTC_DISALLOW_COPY_AND_ASSIGN(SrtpSession);
};
// Class that collects failures of SRTP.
class SrtpStat {
public:
SrtpStat();
// Report RTP protection results to the handler.
void AddProtectRtpResult(uint32_t ssrc, int result);
// Report RTP unprotection results to the handler.
void AddUnprotectRtpResult(uint32_t ssrc, int result);
// Report RTCP protection results to the handler.
void AddProtectRtcpResult(int result);
// Report RTCP unprotection results to the handler.
void AddUnprotectRtcpResult(int result);
// Get silent time (in ms) for SRTP statistics handler.
int signal_silent_time() const { return signal_silent_time_; }
// Set silent time (in ms) for SRTP statistics handler.
void set_signal_silent_time(int signal_silent_time) {
signal_silent_time_ = signal_silent_time;
}
// Sigslot for reporting errors.
sigslot::signal3<uint32_t, SrtpFilter::Mode, SrtpFilter::Error>
SignalSrtpError;
private:
// For each different ssrc and error, we collect statistics separately.
struct FailureKey {
FailureKey()
: ssrc(0),
mode(SrtpFilter::PROTECT),
error(SrtpFilter::ERROR_NONE) {
}
FailureKey(uint32_t in_ssrc,
SrtpFilter::Mode in_mode,
SrtpFilter::Error in_error)
: ssrc(in_ssrc), mode(in_mode), error(in_error) {}
bool operator <(const FailureKey& key) const {
return
(ssrc < key.ssrc) ||
(ssrc == key.ssrc && mode < key.mode) ||
(ssrc == key.ssrc && mode == key.mode && error < key.error);
}
uint32_t ssrc;
SrtpFilter::Mode mode;
SrtpFilter::Error error;
};
// For tracing conditions for signaling, currently we only use
// last_signal_time. Wrap this as a struct so that later on, if we need any
// other improvements, it will be easier.
struct FailureStat {
FailureStat()
: last_signal_time(0) {
}
explicit FailureStat(uint32_t in_last_signal_time)
: last_signal_time(in_last_signal_time) {}
void Reset() {
last_signal_time = 0;
}
int64_t last_signal_time;
};
// Inspect SRTP result and signal error if needed.
void HandleSrtpResult(const FailureKey& key);
std::map<FailureKey, FailureStat> failures_;
// Threshold in ms to silent the signaling errors.
int signal_silent_time_;
RTC_DISALLOW_COPY_AND_ASSIGN(SrtpStat);
};
} // namespace cricket
#endif // WEBRTC_PC_SRTPFILTER_H_