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* Copyright 2004 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.
// P2PTransportChannel wraps up the state management of the connection between
// two P2P clients. Clients have candidate ports for connecting, and
// connections which are combinations of candidates from each end (Alice and
// Bob each have candidates, one candidate from Alice and one candidate from
// Bob are used to make a connection, repeat to make many connections).
// When all of the available connections become invalid (non-writable), we
// kick off a process of determining more candidates and more connections.
#include <map>
#include <memory>
#include <set>
#include <string>
#include <vector>
#include "webrtc/base/constructormagic.h"
#include "webrtc/p2p/base/candidate.h"
#include "webrtc/p2p/base/candidatepairinterface.h"
#include "webrtc/p2p/base/p2ptransport.h"
#include "webrtc/p2p/base/portallocator.h"
#include "webrtc/p2p/base/portinterface.h"
#include "webrtc/p2p/base/transportchannelimpl.h"
#include "webrtc/base/asyncpacketsocket.h"
#include "webrtc/base/sigslot.h"
namespace cricket {
extern const int WEAK_PING_INTERVAL;
static const int MIN_PINGS_AT_WEAK_PING_INTERVAL = 3;
struct IceParameters {
std::string ufrag;
std::string pwd;
IceParameters(const std::string& ice_ufrag, const std::string& ice_pwd)
: ufrag(ice_ufrag), pwd(ice_pwd) {}
bool operator==(const IceParameters& other) {
return ufrag == other.ufrag && pwd == other.pwd;
bool operator!=(const IceParameters& other) { return !(*this == other); }
// Adds the port on which the candidate originated.
class RemoteCandidate : public Candidate {
RemoteCandidate(const Candidate& c, PortInterface* origin_port)
: Candidate(c), origin_port_(origin_port) {}
PortInterface* origin_port() { return origin_port_; }
PortInterface* origin_port_;
// P2PTransportChannel manages the candidates and connection process to keep
// two P2P clients connected to each other.
class P2PTransportChannel : public TransportChannelImpl,
public rtc::MessageHandler {
P2PTransportChannel(const std::string& transport_name,
int component,
PortAllocator* allocator);
// TODO(mikescarlett): Deprecated. Remove when Chromium's
// IceTransportChannel does not depend on this.
P2PTransportChannel(const std::string& transport_name,
int component,
P2PTransport* transport,
PortAllocator* allocator);
virtual ~P2PTransportChannel();
// From TransportChannelImpl:
TransportChannelState GetState() const override;
void SetIceRole(IceRole role) override;
IceRole GetIceRole() const override { return ice_role_; }
void SetIceTiebreaker(uint64_t tiebreaker) override;
void SetIceCredentials(const std::string& ice_ufrag,
const std::string& ice_pwd) override;
void SetRemoteIceCredentials(const std::string& ice_ufrag,
const std::string& ice_pwd) override;
void SetRemoteIceMode(IceMode mode) override;
void Connect() override;
void MaybeStartGathering() override;
IceGatheringState gathering_state() const override {
return gathering_state_;
void AddRemoteCandidate(const Candidate& candidate) override;
void RemoveRemoteCandidate(const Candidate& candidate) override;
// Sets the parameters in IceConfig. We do not set them blindly. Instead, we
// only update the parameter if it is considered set in |config|. For example,
// a negative value of receiving_timeout will be considered "not set" and we
// will not use it to update the respective parameter in |config_|.
void SetIceConfig(const IceConfig& config) override;
const IceConfig& config() const;
// From TransportChannel:
int SendPacket(const char* data,
size_t len,
const rtc::PacketOptions& options,
int flags) override;
int SetOption(rtc::Socket::Option opt, int value) override;
bool GetOption(rtc::Socket::Option opt, int* value) override;
int GetError() override { return error_; }
bool GetStats(std::vector<ConnectionInfo>* stats) override;
const Connection* best_connection() const { return best_connection_; }
void set_incoming_only(bool value) { incoming_only_ = value; }
// Note: This is only for testing purpose.
// |ports_| should not be changed from outside.
const std::vector<PortInterface*>& ports() { return ports_; }
IceMode remote_ice_mode() const { return remote_ice_mode_; }
// DTLS methods.
bool IsDtlsActive() const override { return false; }
// Default implementation.
bool GetSslRole(rtc::SSLRole* role) const override { return false; }
bool SetSslRole(rtc::SSLRole role) override { return false; }
// Set up the ciphers to use for DTLS-SRTP.
bool SetSrtpCryptoSuites(const std::vector<int>& ciphers) override {
return false;
// Find out which DTLS-SRTP cipher was negotiated.
bool GetSrtpCryptoSuite(int* cipher) override { return false; }
// Find out which DTLS cipher was negotiated.
bool GetSslCipherSuite(int* cipher) override { return false; }
// Returns null because the channel is not encrypted by default.
rtc::scoped_refptr<rtc::RTCCertificate> GetLocalCertificate() const override {
return nullptr;
std::unique_ptr<rtc::SSLCertificate> GetRemoteSSLCertificate()
const override {
return nullptr;
// Allows key material to be extracted for external encryption.
bool ExportKeyingMaterial(const std::string& label,
const uint8_t* context,
size_t context_len,
bool use_context,
uint8_t* result,
size_t result_len) override {
return false;
bool SetLocalCertificate(
const rtc::scoped_refptr<rtc::RTCCertificate>& certificate) override {
return false;
// Set DTLS Remote fingerprint. Must be after local identity set.
bool SetRemoteFingerprint(const std::string& digest_alg,
const uint8_t* digest,
size_t digest_len) override {
return false;
int receiving_timeout() const { return config_.receiving_timeout; }
int check_receiving_interval() const { return check_receiving_interval_; }
// Helper method used only in unittest.
rtc::DiffServCodePoint DefaultDscpValue() const;
// Public for unit tests.
Connection* FindNextPingableConnection();
void MarkConnectionPinged(Connection* conn);
// Public for unit tests.
const std::vector<Connection*>& connections() const { return connections_; }
// Public for unit tests.
PortAllocatorSession* allocator_session() {
return allocator_sessions_.back().get();
// Public for unit tests.
const std::vector<RemoteCandidate>& remote_candidates() const {
return remote_candidates_;
rtc::Thread* thread() { return worker_thread_; }
bool IsGettingPorts() { return allocator_session()->IsGettingPorts(); }
// A transport channel is weak if the current best connection is either
// not receiving or not writable, or if there is no best connection at all.
bool weak() const;
void UpdateConnectionStates();
void RequestSort();
void SortConnections();
void SwitchBestConnectionTo(Connection* conn);
void UpdateState();
void HandleAllTimedOut();
void MaybeStopPortAllocatorSessions();
TransportChannelState ComputeState() const;
Connection* GetBestConnectionOnNetwork(rtc::Network* network) const;
bool CreateConnections(const Candidate& remote_candidate,
PortInterface* origin_port);
bool CreateConnection(PortInterface* port,
const Candidate& remote_candidate,
PortInterface* origin_port);
bool FindConnection(cricket::Connection* connection) const;
uint32_t GetRemoteCandidateGeneration(const Candidate& candidate);
bool IsDuplicateRemoteCandidate(const Candidate& candidate);
void RememberRemoteCandidate(const Candidate& remote_candidate,
PortInterface* origin_port);
bool IsPingable(Connection* conn, int64_t now);
bool IsBestConnectionPingable(int64_t now);
int CalculateActiveWritablePingInterval(Connection* conn, int64_t now);
void PingConnection(Connection* conn);
void AddAllocatorSession(std::unique_ptr<PortAllocatorSession> session);
void AddConnection(Connection* connection);
void OnPortReady(PortAllocatorSession *session, PortInterface* port);
void OnCandidatesReady(PortAllocatorSession *session,
const std::vector<Candidate>& candidates);
void OnCandidatesAllocationDone(PortAllocatorSession* session);
void OnUnknownAddress(PortInterface* port,
const rtc::SocketAddress& addr,
ProtocolType proto,
IceMessage* stun_msg,
const std::string& remote_username,
bool port_muxed);
void OnPortDestroyed(PortInterface* port);
void OnPortNetworkInactive(PortInterface* port);
void OnRoleConflict(PortInterface* port);
void OnConnectionStateChange(Connection* connection);
void OnReadPacket(Connection *connection, const char *data, size_t len,
const rtc::PacketTime& packet_time);
void OnSentPacket(const rtc::SentPacket& sent_packet);
void OnReadyToSend(Connection* connection);
void OnConnectionDestroyed(Connection *connection);
void OnNominated(Connection* conn);
void OnMessage(rtc::Message* pmsg) override;
void OnSort();
void OnCheckAndPing();
void PruneConnections();
Connection* best_nominated_connection() const;
bool IsBackupConnection(Connection* conn) const;
Connection* FindConnectionToPing(int64_t now);
Connection* FindOldestConnectionNeedingTriggeredCheck(int64_t now);
// Between |conn1| and |conn2|, this function returns the one which should
// be pinged first.
Connection* SelectMostPingableConnection(Connection* conn1,
Connection* conn2);
// Select the connection which is Relay/Relay. If both of them are,
// UDP relay protocol takes precedence.
Connection* MostLikelyToWork(Connection* conn1, Connection* conn2);
// Compare the last_ping_sent time and return the one least recently pinged.
Connection* LeastRecentlyPinged(Connection* conn1, Connection* conn2);
// Returns the latest remote ICE parameters or nullptr if there are no remote
// ICE parameters yet.
IceParameters* remote_ice() {
return remote_ice_parameters_.empty() ? nullptr
: &remote_ice_parameters_.back();
// Returns the remote IceParameters and generation that match |ufrag|
// if found, and returns nullptr otherwise.
const IceParameters* FindRemoteIceFromUfrag(const std::string& ufrag,
uint32_t* generation);
// Returns the index of the latest remote ICE parameters, or 0 if no remote
// ICE parameters have been received.
uint32_t remote_ice_generation() {
return remote_ice_parameters_.empty()
? 0
: static_cast<uint32_t>(remote_ice_parameters_.size() - 1);
PortAllocator* allocator_;
rtc::Thread* worker_thread_;
bool incoming_only_;
int error_;
std::vector<std::unique_ptr<PortAllocatorSession>> allocator_sessions_;
std::vector<PortInterface *> ports_;
// |connections_| is a sorted list with the first one always be the
// |best_connection_| when it's not nullptr. The combination of
// |pinged_connections_| and |unpinged_connections_| has the same
// connections as |connections_|. These 2 sets maintain whether a
// connection should be pinged next or not.
std::vector<Connection *> connections_;
std::set<Connection*> pinged_connections_;
std::set<Connection*> unpinged_connections_;
Connection* best_connection_;
// Connection selected by the controlling agent. This should be used only
// at controlled side when protocol type is RFC5245.
Connection* pending_best_connection_;
std::vector<RemoteCandidate> remote_candidates_;
bool sort_dirty_; // indicates whether another sort is needed right now
bool had_connection_ = false; // if connections_ has ever been nonempty
typedef std::map<rtc::Socket::Option, int> OptionMap;
OptionMap options_;
std::string ice_ufrag_;
std::string ice_pwd_;
std::vector<IceParameters> remote_ice_parameters_;
IceMode remote_ice_mode_;
IceRole ice_role_;
uint64_t tiebreaker_;
IceGatheringState gathering_state_;
int check_receiving_interval_;
int64_t last_ping_sent_ms_ = 0;
int weak_ping_interval_ = WEAK_PING_INTERVAL;
TransportChannelState state_ = TransportChannelState::STATE_INIT;
IceConfig config_;
int last_sent_packet_id_ = -1; // -1 indicates no packet was sent before.
} // namespace cricket