text: /*
   *  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.
   */
  
  #ifndef P2P_BASE_PORT_H_
  #define P2P_BASE_PORT_H_
  
  #include <map>
  #include <memory>
  #include <set>
  #include <string>
  #include <utility>
  #include <vector>
  
  #include "absl/types/optional.h"
  #include "api/candidate.h"
  #include "api/packet_socket_factory.h"
  #include "api/rtc_error.h"
  #include "api/transport/stun.h"
  #include "logging/rtc_event_log/events/rtc_event_ice_candidate_pair.h"
  #include "logging/rtc_event_log/events/rtc_event_ice_candidate_pair_config.h"
  #include "logging/rtc_event_log/ice_logger.h"
  #include "p2p/base/candidate_pair_interface.h"
  #include "p2p/base/connection.h"
  #include "p2p/base/connection_info.h"
  #include "p2p/base/p2p_constants.h"
  #include "p2p/base/port_interface.h"
  #include "p2p/base/stun_request.h"
  #include "rtc_base/async_packet_socket.h"
  #include "rtc_base/callback_list.h"
  #include "rtc_base/checks.h"
  #include "rtc_base/net_helper.h"
  #include "rtc_base/network.h"
  #include "rtc_base/proxy_info.h"
  #include "rtc_base/rate_tracker.h"
  #include "rtc_base/socket_address.h"
  #include "rtc_base/system/rtc_export.h"
  #include "rtc_base/third_party/sigslot/sigslot.h"
  #include "rtc_base/thread.h"
  #include "rtc_base/weak_ptr.h"
  
  namespace cricket {
  
  RTC_EXPORT extern const char LOCAL_PORT_TYPE[];
  RTC_EXPORT extern const char STUN_PORT_TYPE[];
  RTC_EXPORT extern const char PRFLX_PORT_TYPE[];
  RTC_EXPORT extern const char RELAY_PORT_TYPE[];
  
  // RFC 6544, TCP candidate encoding rules.
  extern const int DISCARD_PORT;
  extern const char TCPTYPE_ACTIVE_STR[];
  extern const char TCPTYPE_PASSIVE_STR[];
  extern const char TCPTYPE_SIMOPEN_STR[];
  
  enum IcePriorityValue {
    ICE_TYPE_PREFERENCE_RELAY_TLS = 0,
    ICE_TYPE_PREFERENCE_RELAY_TCP = 1,
    ICE_TYPE_PREFERENCE_RELAY_UDP = 2,
    ICE_TYPE_PREFERENCE_PRFLX_TCP = 80,
    ICE_TYPE_PREFERENCE_HOST_TCP = 90,
    ICE_TYPE_PREFERENCE_SRFLX = 100,
    ICE_TYPE_PREFERENCE_PRFLX = 110,
    ICE_TYPE_PREFERENCE_HOST = 126
  };
  
  enum class MdnsNameRegistrationStatus {
    // IP concealment with mDNS is not enabled or the name registration process is
    // not started yet.
    kNotStarted,
    // A request to create and register an mDNS name for a local IP address of a
    // host candidate is sent to the mDNS responder.
    kInProgress,
    // The name registration is complete and the created name is returned by the
    // mDNS responder.
    kCompleted,
  };
  
  // Stats that we can return about the port of a STUN candidate.
  class StunStats {
   public:
    StunStats() = default;
    StunStats(const StunStats&) = default;
    ~StunStats() = default;
  
    StunStats& operator=(const StunStats& other) = default;
  
    int stun_binding_requests_sent = 0;
    int stun_binding_responses_received = 0;
    double stun_binding_rtt_ms_total = 0;
    double stun_binding_rtt_ms_squared_total = 0;
  };
  
  // Stats that we can return about a candidate.
  class CandidateStats {
   public:
    CandidateStats();
    explicit CandidateStats(Candidate candidate);
    CandidateStats(const CandidateStats&);
    ~CandidateStats();
  
    Candidate candidate;
    // STUN port stats if this candidate is a STUN candidate.
    absl::optional<StunStats> stun_stats;
  };
  
  typedef std::vector<CandidateStats> CandidateStatsList;
  
  const char* ProtoToString(ProtocolType proto);
  bool StringToProto(const char* value, ProtocolType* proto);
  
  struct ProtocolAddress {
    rtc::SocketAddress address;
    ProtocolType proto;
  
    ProtocolAddress(const rtc::SocketAddress& a, ProtocolType p)
        : address(a), proto(p) {}
  
    bool operator==(const ProtocolAddress& o) const {
      return address == o.address && proto == o.proto;
    }
    bool operator!=(const ProtocolAddress& o) const { return !(*this == o); }
  };
  
  struct IceCandidateErrorEvent {
    IceCandidateErrorEvent() = default;
    IceCandidateErrorEvent(std::string address,
                           int port,
                           std::string url,
                           int error_code,
                           std::string error_text)
        : address(std::move(address)),
          port(port),
          url(std::move(url)),
          error_code(error_code),
          error_text(std::move(error_text)) {}
  
    std::string address;
    int port = 0;
    std::string url;
    int error_code = 0;
    std::string error_text;
  };
  
  struct CandidatePairChangeEvent {
    CandidatePair selected_candidate_pair;
    int64_t last_data_received_ms;
    std::string reason;
    // How long do we estimate that we've been disconnected.
    int64_t estimated_disconnected_time_ms;
  };
  
  typedef std::set<rtc::SocketAddress> ServerAddresses;
  
  // Represents a local communication mechanism that can be used to create
  // connections to similar mechanisms of the other client.  Subclasses of this
  // one add support for specific mechanisms like local UDP ports.
  class Port : public PortInterface,
               public rtc::MessageHandler,
               public sigslot::has_slots<> {
   public:
    // INIT: The state when a port is just created.
    // KEEP_ALIVE_UNTIL_PRUNED: A port should not be destroyed even if no
    // connection is using it.
    // PRUNED: It will be destroyed if no connection is using it for a period of
    // 30 seconds.
    enum class State { INIT, KEEP_ALIVE_UNTIL_PRUNED, PRUNED };
    Port(rtc::Thread* thread,
         const std::string& type,
         rtc::PacketSocketFactory* factory,
         rtc::Network* network,
         const std::string& username_fragment,
         const std::string& password);
    Port(rtc::Thread* thread,
         const std::string& type,
         rtc::PacketSocketFactory* factory,
         rtc::Network* network,
         uint16_t min_port,
         uint16_t max_port,
         const std::string& username_fragment,
         const std::string& password);
    ~Port() override;
  
    // Note that the port type does NOT uniquely identify different subclasses of
    // Port. Use the 2-tuple of the port type AND the protocol (GetProtocol()) to
    // uniquely identify subclasses. Whenever a new subclass of Port introduces a
    // conflit in the value of the 2-tuple, make sure that the implementation that
    // relies on this 2-tuple for RTTI is properly changed.
    const std::string& Type() const override;
    rtc::Network* Network() const override;
  
    // Methods to set/get ICE role and tiebreaker values.
    IceRole GetIceRole() const override;
    void SetIceRole(IceRole role) override;
  
    void SetIceTiebreaker(uint64_t tiebreaker) override;
    uint64_t IceTiebreaker() const override;
  
    bool SharedSocket() const override;
    void ResetSharedSocket() { shared_socket_ = false; }
  
    // Should not destroy the port even if no connection is using it. Called when
    // a port is ready to use.
    void KeepAliveUntilPruned();
    // Allows a port to be destroyed if no connection is using it.
    void Prune();
  
    // Call to stop any currently pending operations from running.
    void CancelPendingTasks();
  
    // The thread on which this port performs its I/O.
    rtc::Thread* thread() { return thread_; }
  
    // The factory used to create the sockets of this port.
    rtc::PacketSocketFactory* socket_factory() const { return factory_; }
    void set_socket_factory(rtc::PacketSocketFactory* factory) {
      factory_ = factory;
    }
  
    // For debugging purposes.
    const std::string& content_name() const { return content_name_; }
    void set_content_name(const std::string& content_name) {
      content_name_ = content_name;
    }
  
    int component() const { return component_; }
    void set_component(int component) { component_ = component; }
  
    bool send_retransmit_count_attribute() const {
      return send_retransmit_count_attribute_;
    }
    void set_send_retransmit_count_attribute(bool enable) {
      send_retransmit_count_attribute_ = enable;
    }
  
    // Identifies the generation that this port was created in.
    uint32_t generation() const { return generation_; }
    void set_generation(uint32_t generation) { generation_ = generation; }
  
    const std::string username_fragment() const;
    const std::string& password() const { return password_; }
  
    // May be called when this port was initially created by a pooled
    // PortAllocatorSession, and is now being assigned to an ICE transport.
    // Updates the information for candidates as well.
    void SetIceParameters(int component,
                          const std::string& username_fragment,
                          const std::string& password);
  
    // Fired when candidates are discovered by the port. When all candidates
    // are discovered that belong to port SignalAddressReady is fired.
    sigslot::signal2<Port*, const Candidate&> SignalCandidateReady;
    // Provides all of the above information in one handy object.
    const std::vector<Candidate>& Candidates() const override;
    // Fired when candidate discovery failed using certain server.
    sigslot::signal2<Port*, const IceCandidateErrorEvent&> SignalCandidateError;
  
    // SignalPortComplete is sent when port completes the task of candidates
    // allocation.
    sigslot::signal1<Port*> SignalPortComplete;
    // This signal sent when port fails to allocate candidates and this port
    // can't be used in establishing the connections. When port is in shared mode
    // and port fails to allocate one of the candidates, port shouldn't send
    // this signal as other candidates might be usefull in establishing the
    // connection.
    sigslot::signal1<Port*> SignalPortError;
  
    void SubscribePortDestroyed(
        std::function<void(PortInterface*)> callback) override;
    void SendPortDestroyed(Port* port);
    // Returns a map containing all of the connections of this port, keyed by the
    // remote address.
    typedef std::map<rtc::SocketAddress, Connection*> AddressMap;
    const AddressMap& connections() { return connections_; }
  
    // Returns the connection to the given address or NULL if none exists.
    Connection* GetConnection(const rtc::SocketAddress& remote_addr) override;
  
    // Called each time a connection is created.
    sigslot::signal2<Port*, Connection*> SignalConnectionCreated;
  
    // In a shared socket mode each port which shares the socket will decide
    // to accept the packet based on the |remote_addr|. Currently only UDP
    // port implemented this method.
    // TODO(mallinath) - Make it pure virtual.
    virtual bool HandleIncomingPacket(rtc::AsyncPacketSocket* socket,
                                      const char* data,
                                      size_t size,
                                      const rtc::SocketAddress& remote_addr,
                                      int64_t packet_time_us);
  
    // Shall the port handle packet from this |remote_addr|.
    // This method is overridden by TurnPort.
    virtual bool CanHandleIncomingPacketsFrom(
        const rtc::SocketAddress& remote_addr) const;
  
    // Sends a response error to the given request.
    void SendBindingErrorResponse(StunMessage* request,
                                  const rtc::SocketAddress& addr,
                                  int error_code,
                                  const std::string& reason) override;
    void SendUnknownAttributesErrorResponse(
        StunMessage* request,
        const rtc::SocketAddress& addr,
        const std::vector<uint16_t>& unknown_types);
  
    void set_proxy(const std::string& user_agent, const rtc::ProxyInfo& proxy) {
      user_agent_ = user_agent;
      proxy_ = proxy;
    }
    const std::string& user_agent() { return user_agent_; }
    const rtc::ProxyInfo& proxy() { return proxy_; }
  
    void EnablePortPackets() override;
  
    // Called if the port has no connections and is no longer useful.
    void Destroy();
  
    void OnMessage(rtc::Message* pmsg) override;
  
    // Debugging description of this port
    std::string ToString() const override;
    uint16_t min_port() { return min_port_; }
    uint16_t max_port() { return max_port_; }
  
    // Timeout shortening function to speed up unit tests.
    void set_timeout_delay(int delay);
  
    // This method will return local and remote username fragements from the
    // stun username attribute if present.
    bool ParseStunUsername(const StunMessage* stun_msg,
                           std::string* local_username,
                           std::string* remote_username) const;
    void CreateStunUsername(const std::string& remote_username,
                            std::string* stun_username_attr_str) const;
  
    bool MaybeIceRoleConflict(const rtc::SocketAddress& addr,
                              IceMessage* stun_msg,
                              const std::string& remote_ufrag);
  
    // Called when a packet has been sent to the socket.
    // This is made pure virtual to notify subclasses of Port that they MUST
    // listen to AsyncPacketSocket::SignalSentPacket and then call
    // PortInterface::OnSentPacket.
    virtual void OnSentPacket(rtc::AsyncPacketSocket* socket,
                              const rtc::SentPacket& sent_packet) = 0;
  
    // Called when the socket is currently able to send.
    void OnReadyToSend();
  
    // Called when the Connection discovers a local peer reflexive candidate.
    // Returns the index of the new local candidate.
    size_t AddPrflxCandidate(const Candidate& local);
  
    int16_t network_cost() const { return network_cost_; }
  
    void GetStunStats(absl::optional<StunStats>* stats) override {}
  
    // Foundation:  An arbitrary string that is the same for two candidates
    //   that have the same type, base IP address, protocol (UDP, TCP,
    //   etc.), and STUN or TURN server.  If any of these are different,
    //   then the foundation will be different.  Two candidate pairs with
    //   the same foundation pairs are likely to have similar network
    //   characteristics. Foundations are used in the frozen algorithm.
    static std::string ComputeFoundation(const std::string& type,
                                         const std::string& protocol,
                                         const std::string& relay_protocol,
                                         const rtc::SocketAddress& base_address);
  
   protected:
    enum { MSG_DESTROY_IF_DEAD = 0, MSG_FIRST_AVAILABLE };
  
    virtual void UpdateNetworkCost();
  
    void set_type(const std::string& type) { type_ = type; }
  
    void AddAddress(const rtc::SocketAddress& address,
                    const rtc::SocketAddress& base_address,
                    const rtc::SocketAddress& related_address,
                    const std::string& protocol,
                    const std::string& relay_protocol,
                    const std::string& tcptype,
                    const std::string& type,
                    uint32_t type_preference,
                    uint32_t relay_preference,
                    const std::string& url,
                    bool is_final);
  
    void FinishAddingAddress(const Candidate& c, bool is_final);
  
    virtual void PostAddAddress(bool is_final);
  
    // Adds the given connection to the map keyed by the remote candidate address.
    // If an existing connection has the same address, the existing one will be
    // replaced and destroyed.
    void AddOrReplaceConnection(Connection* conn);
  
    // Called when a packet is received from an unknown address that is not
    // currently a connection.  If this is an authenticated STUN binding request,
    // then we will signal the client.
    void OnReadPacket(const char* data,
                      size_t size,
                      const rtc::SocketAddress& addr,
                      ProtocolType proto);
  
    // If the given data comprises a complete and correct STUN message then the
    // return value is true, otherwise false. If the message username corresponds
    // with this port's username fragment, msg will contain the parsed STUN
    // message.  Otherwise, the function may send a STUN response internally.
    // remote_username contains the remote fragment of the STUN username.
    bool GetStunMessage(const char* data,
                        size_t size,
                        const rtc::SocketAddress& addr,
                        std::unique_ptr<IceMessage>* out_msg,
                        std::string* out_username);
  
    // Checks if the address in addr is compatible with the port's ip.
    bool IsCompatibleAddress(const rtc::SocketAddress& addr);
  
    // Returns DSCP value packets generated by the port itself should use.
    virtual rtc::DiffServCodePoint StunDscpValue() const;
  
    // Extra work to be done in subclasses when a connection is destroyed.
    virtual void HandleConnectionDestroyed(Connection* conn) {}
  
    void CopyPortInformationToPacketInfo(rtc::PacketInfo* info) const;
  
    MdnsNameRegistrationStatus mdns_name_registration_status() const {
      return mdns_name_registration_status_;
    }
    void set_mdns_name_registration_status(MdnsNameRegistrationStatus status) {
      mdns_name_registration_status_ = status;
    }
  
   private:
    void Construct();
    // Called when one of our connections deletes itself.
    void OnConnectionDestroyed(Connection* conn);
  
    void OnNetworkTypeChanged(const rtc::Network* network);
  
    rtc::Thread* const thread_;
    rtc::PacketSocketFactory* factory_;
    std::string type_;
    bool send_retransmit_count_attribute_;
    rtc::Network* network_;
    uint16_t min_port_;
    uint16_t max_port_;
    std::string content_name_;
    int component_;
    uint32_t generation_;
    // In order to establish a connection to this Port (so that real data can be
    // sent through), the other side must send us a STUN binding request that is
    // authenticated with this username_fragment and password.
    // PortAllocatorSession will provide these username_fragment and password.
    //
    // Note: we should always use username_fragment() instead of using
    // |ice_username_fragment_| directly. For the details see the comment on
    // username_fragment().
    std::string ice_username_fragment_;
    std::string password_;
    std::vector<Candidate> candidates_;
    AddressMap connections_;
    int timeout_delay_;
    bool enable_port_packets_;
    IceRole ice_role_;
    uint64_t tiebreaker_;
    bool shared_socket_;
    // Information to use when going through a proxy.
    std::string user_agent_;
    rtc::ProxyInfo proxy_;
  
    // A virtual cost perceived by the user, usually based on the network type
    // (WiFi. vs. Cellular). It takes precedence over the priority when
    // comparing two connections.
    int16_t network_cost_;
    State state_ = State::INIT;
    int64_t last_time_all_connections_removed_ = 0;
    MdnsNameRegistrationStatus mdns_name_registration_status_ =
        MdnsNameRegistrationStatus::kNotStarted;
  
    rtc::WeakPtrFactory<Port> weak_factory_;
  
    bool MaybeObfuscateAddress(Candidate* c,
                               const std::string& type,
                               bool is_final);
  
    friend class Connection;
    webrtc::CallbackList<PortInterface*> port_destroyed_callback_list_;
  };
  
  }  // namespace cricket
  
  #endif  // P2P_BASE_PORT_H_
  