rtc_base/nat_socket_factory.cc - src - Git at Google

 /*
  *  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.
  */

 #include "rtc_base/nat_socket_factory.h"

 #include "rtc_base/arraysize.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/nat_server.h"
 #include "rtc_base/virtual_socket_server.h"

 namespace rtc {

 // Packs the given socketaddress into the buffer in buf, in the quasi-STUN
 // format that the natserver uses.
 // Returns 0 if an invalid address is passed.
 size_t PackAddressForNAT(char* buf,
                          size_t buf_size,
                          const SocketAddress& remote_addr) {
   const IPAddress& ip = remote_addr.ipaddr();
   int family = ip.family();
   buf[0] = 0;
   buf[1] = family;
   // Writes the port.
   *(reinterpret_cast<uint16_t*>(&buf[2])) = HostToNetwork16(remote_addr.port());
   if (family == AF_INET) {
     RTC_DCHECK(buf_size >= kNATEncodedIPv4AddressSize);
     in_addr v4addr = ip.ipv4_address();
     memcpy(&buf[4], &v4addr, kNATEncodedIPv4AddressSize - 4);
     return kNATEncodedIPv4AddressSize;
   } else if (family == AF_INET6) {
     RTC_DCHECK(buf_size >= kNATEncodedIPv6AddressSize);
     in6_addr v6addr = ip.ipv6_address();
     memcpy(&buf[4], &v6addr, kNATEncodedIPv6AddressSize - 4);
     return kNATEncodedIPv6AddressSize;
   }
   return 0U;
 }

 // Decodes the remote address from a packet that has been encoded with the nat's
 // quasi-STUN format. Returns the length of the address (i.e., the offset into
 // data where the original packet starts).
 size_t UnpackAddressFromNAT(const char* buf,
                             size_t buf_size,
                             SocketAddress* remote_addr) {
   RTC_DCHECK(buf_size >= 8);
   RTC_DCHECK(buf[0] == 0);
   int family = buf[1];
   uint16_t port =
       NetworkToHost16(*(reinterpret_cast<const uint16_t*>(&buf[2])));
   if (family == AF_INET) {
     const in_addr* v4addr = reinterpret_cast<const in_addr*>(&buf[4]);
     *remote_addr = SocketAddress(IPAddress(*v4addr), port);
     return kNATEncodedIPv4AddressSize;
   } else if (family == AF_INET6) {
     RTC_DCHECK(buf_size >= 20);
     const in6_addr* v6addr = reinterpret_cast<const in6_addr*>(&buf[4]);
     *remote_addr = SocketAddress(IPAddress(*v6addr), port);
     return kNATEncodedIPv6AddressSize;
   }
   return 0U;
 }

 // NATSocket
 class NATSocket : public AsyncSocket, public sigslot::has_slots<> {
  public:
   explicit NATSocket(NATInternalSocketFactory* sf, int family, int type)
       : sf_(sf),
         family_(family),
         type_(type),
         connected_(false),
         socket_(nullptr),
         buf_(nullptr),
         size_(0) {}

   ~NATSocket() override {
     delete socket_;
     delete[] buf_;
   }

   SocketAddress GetLocalAddress() const override {
     return (socket_) ? socket_->GetLocalAddress() : SocketAddress();
   }

   SocketAddress GetRemoteAddress() const override {
     return remote_addr_;  // will be NIL if not connected
   }

   int Bind(const SocketAddress& addr) override {
     if (socket_) {  // already bound, bubble up error
       return -1;
     }

     return BindInternal(addr);
   }

   int Connect(const SocketAddress& addr) override {
     int result = 0;
     // If we're not already bound (meaning `socket_` is null), bind to ANY
     // address.
     if (!socket_) {
       result = BindInternal(SocketAddress(GetAnyIP(family_), 0));
       if (result < 0) {
         return result;
       }
     }

     if (type_ == SOCK_STREAM) {
       result = socket_->Connect(server_addr_.IsNil() ? addr : server_addr_);
     } else {
       connected_ = true;
     }

     if (result >= 0) {
       remote_addr_ = addr;
     }

     return result;
   }

   int Send(const void* data, size_t size) override {
     RTC_DCHECK(connected_);
     return SendTo(data, size, remote_addr_);
   }

   int SendTo(const void* data,
              size_t size,
              const SocketAddress& addr) override {
     RTC_DCHECK(!connected_ || addr == remote_addr_);
     if (server_addr_.IsNil() || type_ == SOCK_STREAM) {
       return socket_->SendTo(data, size, addr);
     }
     // This array will be too large for IPv4 packets, but only by 12 bytes.
     std::unique_ptr<char[]> buf(new char[size + kNATEncodedIPv6AddressSize]);
     size_t addrlength =
         PackAddressForNAT(buf.get(), size + kNATEncodedIPv6AddressSize, addr);
     size_t encoded_size = size + addrlength;
     memcpy(buf.get() + addrlength, data, size);
     int result = socket_->SendTo(buf.get(), encoded_size, server_addr_);
     if (result >= 0) {
       RTC_DCHECK(result == static_cast<int>(encoded_size));
       result = result - static_cast<int>(addrlength);
     }
     return result;
   }

   int Recv(void* data, size_t size, int64_t* timestamp) override {
     SocketAddress addr;
     return RecvFrom(data, size, &addr, timestamp);
   }

   int RecvFrom(void* data,
                size_t size,
                SocketAddress* out_addr,
                int64_t* timestamp) override {
     if (server_addr_.IsNil() || type_ == SOCK_STREAM) {
       return socket_->RecvFrom(data, size, out_addr, timestamp);
     }
     // Make sure we have enough room to read the requested amount plus the
     // largest possible header address.
     SocketAddress remote_addr;
     Grow(size + kNATEncodedIPv6AddressSize);

     // Read the packet from the socket.
     int result = socket_->RecvFrom(buf_, size_, &remote_addr, timestamp);
     if (result >= 0) {
       RTC_DCHECK(remote_addr == server_addr_);

       // TODO: we need better framing so we know how many bytes we can
       // return before we need to read the next address. For UDP, this will be
       // fine as long as the reader always reads everything in the packet.
       RTC_DCHECK((size_t)result < size_);

       // Decode the wire packet into the actual results.
       SocketAddress real_remote_addr;
       size_t addrlength = UnpackAddressFromNAT(buf_, result, &real_remote_addr);
       memcpy(data, buf_ + addrlength, result - addrlength);

       // Make sure this packet should be delivered before returning it.
       if (!connected_ || (real_remote_addr == remote_addr_)) {
         if (out_addr)
           *out_addr = real_remote_addr;
         result = result - static_cast<int>(addrlength);
       } else {
         RTC_LOG(LS_ERROR) << "Dropping packet from unknown remote address: "
                           << real_remote_addr.ToString();
         result = 0;  // Tell the caller we didn't read anything
       }
     }

     return result;
   }

   int Close() override {
     int result = 0;
     if (socket_) {
       result = socket_->Close();
       if (result >= 0) {
         connected_ = false;
         remote_addr_ = SocketAddress();
         delete socket_;
         socket_ = nullptr;
       }
     }
     return result;
   }

   int Listen(int backlog) override { return socket_->Listen(backlog); }
   AsyncSocket* Accept(SocketAddress* paddr) override {
     return socket_->Accept(paddr);
   }
   int GetError() const override {
     return socket_ ? socket_->GetError() : error_;
   }
   void SetError(int error) override {
     if (socket_) {
       socket_->SetError(error);
     } else {
       error_ = error;
     }
   }
   ConnState GetState() const override {
     return connected_ ? CS_CONNECTED : CS_CLOSED;
   }
   int GetOption(Option opt, int* value) override {
     return socket_ ? socket_->GetOption(opt, value) : -1;
   }
   int SetOption(Option opt, int value) override {
     return socket_ ? socket_->SetOption(opt, value) : -1;
   }

   void OnConnectEvent(AsyncSocket* socket) {
     // If we're NATed, we need to send a message with the real addr to use.
     RTC_DCHECK(socket == socket_);
     if (server_addr_.IsNil()) {
       connected_ = true;
       SignalConnectEvent(this);
     } else {
       SendConnectRequest();
     }
   }
   void OnReadEvent(AsyncSocket* socket) {
     // If we're NATed, we need to process the connect reply.
     RTC_DCHECK(socket == socket_);
     if (type_ == SOCK_STREAM && !server_addr_.IsNil() && !connected_) {
       HandleConnectReply();
     } else {
       SignalReadEvent(this);
     }
   }
   void OnWriteEvent(AsyncSocket* socket) {
     RTC_DCHECK(socket == socket_);
     SignalWriteEvent(this);
   }
   void OnCloseEvent(AsyncSocket* socket, int error) {
     RTC_DCHECK(socket == socket_);
     SignalCloseEvent(this, error);
   }

  private:
   int BindInternal(const SocketAddress& addr) {
     RTC_DCHECK(!socket_);

     int result;
     socket_ = sf_->CreateInternalSocket(family_, type_, addr, &server_addr_);
     result = (socket_) ? socket_->Bind(addr) : -1;
     if (result >= 0) {
       socket_->SignalConnectEvent.connect(this, &NATSocket::OnConnectEvent);
       socket_->SignalReadEvent.connect(this, &NATSocket::OnReadEvent);
       socket_->SignalWriteEvent.connect(this, &NATSocket::OnWriteEvent);
       socket_->SignalCloseEvent.connect(this, &NATSocket::OnCloseEvent);
     } else {
       server_addr_.Clear();
       delete socket_;
       socket_ = nullptr;
     }

     return result;
   }

   // Makes sure the buffer is at least the given size.
   void Grow(size_t new_size) {
     if (size_ < new_size) {
       delete[] buf_;
       size_ = new_size;
       buf_ = new char[size_];
     }
   }

   // Sends the destination address to the server to tell it to connect.
   void SendConnectRequest() {
     char buf[kNATEncodedIPv6AddressSize];
     size_t length = PackAddressForNAT(buf, arraysize(buf), remote_addr_);
     socket_->Send(buf, length);
   }

   // Handles the byte sent back from the server and fires the appropriate event.
   void HandleConnectReply() {
     char code;
     socket_->Recv(&code, sizeof(code), nullptr);
     if (code == 0) {
       connected_ = true;
       SignalConnectEvent(this);
     } else {
       Close();
       SignalCloseEvent(this, code);
     }
   }

   NATInternalSocketFactory* sf_;
   int family_;
   int type_;
   bool connected_;
   SocketAddress remote_addr_;
   SocketAddress server_addr_;  // address of the NAT server
   AsyncSocket* socket_;
   // Need to hold error in case it occurs before the socket is created.
   int error_ = 0;
   char* buf_;
   size_t size_;
 };

 // NATSocketFactory
 NATSocketFactory::NATSocketFactory(SocketFactory* factory,
                                    const SocketAddress& nat_udp_addr,
                                    const SocketAddress& nat_tcp_addr)
     : factory_(factory),
       nat_udp_addr_(nat_udp_addr),
       nat_tcp_addr_(nat_tcp_addr) {}

 Socket* NATSocketFactory::CreateSocket(int family, int type) {
   return new NATSocket(this, family, type);
 }

 AsyncSocket* NATSocketFactory::CreateAsyncSocket(int family, int type) {
   return new NATSocket(this, family, type);
 }

 AsyncSocket* NATSocketFactory::CreateInternalSocket(
     int family,
     int type,
     const SocketAddress& local_addr,
     SocketAddress* nat_addr) {
   if (type == SOCK_STREAM) {
     *nat_addr = nat_tcp_addr_;
   } else {
     *nat_addr = nat_udp_addr_;
   }
   return factory_->CreateAsyncSocket(family, type);
 }

 // NATSocketServer
 NATSocketServer::NATSocketServer(SocketServer* server)
     : server_(server), msg_queue_(nullptr) {}

 NATSocketServer::Translator* NATSocketServer::GetTranslator(
     const SocketAddress& ext_ip) {
   return nats_.Get(ext_ip);
 }

 NATSocketServer::Translator* NATSocketServer::AddTranslator(
     const SocketAddress& ext_ip,
     const SocketAddress& int_ip,
     NATType type) {
   // Fail if a translator already exists with this extternal address.
   if (nats_.Get(ext_ip))
     return nullptr;

   return nats_.Add(ext_ip, new Translator(this, type, int_ip, server_, ext_ip));
 }

 void NATSocketServer::RemoveTranslator(const SocketAddress& ext_ip) {
   nats_.Remove(ext_ip);
 }

 Socket* NATSocketServer::CreateSocket(int family, int type) {
   return new NATSocket(this, family, type);
 }

 AsyncSocket* NATSocketServer::CreateAsyncSocket(int family, int type) {
   return new NATSocket(this, family, type);
 }

 void NATSocketServer::SetMessageQueue(Thread* queue) {
   msg_queue_ = queue;
   server_->SetMessageQueue(queue);
 }

 bool NATSocketServer::Wait(int cms, bool process_io) {
   return server_->Wait(cms, process_io);
 }

 void NATSocketServer::WakeUp() {
   server_->WakeUp();
 }

 AsyncSocket* NATSocketServer::CreateInternalSocket(
     int family,
     int type,
     const SocketAddress& local_addr,
     SocketAddress* nat_addr) {
   AsyncSocket* socket = nullptr;
   Translator* nat = nats_.FindClient(local_addr);
   if (nat) {
     socket = nat->internal_factory()->CreateAsyncSocket(family, type);
     *nat_addr = (type == SOCK_STREAM) ? nat->internal_tcp_address()
                                       : nat->internal_udp_address();
   } else {
     socket = server_->CreateAsyncSocket(family, type);
   }
   return socket;
 }

 // NATSocketServer::Translator
 NATSocketServer::Translator::Translator(NATSocketServer* server,
                                         NATType type,
                                         const SocketAddress& int_ip,
                                         SocketFactory* ext_factory,
                                         const SocketAddress& ext_ip)
     : server_(server) {
   // Create a new private network, and a NATServer running on the private
   // network that bridges to the external network. Also tell the private
   // network to use the same message queue as us.
   internal_server_ = std::make_unique<VirtualSocketServer>();
   internal_server_->SetMessageQueue(server_->queue());
   nat_server_ = std::make_unique<NATServer>(
       type, internal_server_.get(), int_ip, int_ip, ext_factory, ext_ip);
 }

 NATSocketServer::Translator::~Translator() {
   internal_server_->SetMessageQueue(nullptr);
 }

 NATSocketServer::Translator* NATSocketServer::Translator::GetTranslator(
     const SocketAddress& ext_ip) {
   return nats_.Get(ext_ip);
 }

 NATSocketServer::Translator* NATSocketServer::Translator::AddTranslator(
     const SocketAddress& ext_ip,
     const SocketAddress& int_ip,
     NATType type) {
   // Fail if a translator already exists with this extternal address.
   if (nats_.Get(ext_ip))
     return nullptr;

   AddClient(ext_ip);
   return nats_.Add(ext_ip,
                    new Translator(server_, type, int_ip, server_, ext_ip));
 }
 void NATSocketServer::Translator::RemoveTranslator(
     const SocketAddress& ext_ip) {
   nats_.Remove(ext_ip);
   RemoveClient(ext_ip);
 }

 bool NATSocketServer::Translator::AddClient(const SocketAddress& int_ip) {
   // Fail if a client already exists with this internal address.
   if (clients_.find(int_ip) != clients_.end())
     return false;

   clients_.insert(int_ip);
   return true;
 }

 void NATSocketServer::Translator::RemoveClient(const SocketAddress& int_ip) {
   std::set<SocketAddress>::iterator it = clients_.find(int_ip);
   if (it != clients_.end()) {
     clients_.erase(it);
   }
 }

 NATSocketServer::Translator* NATSocketServer::Translator::FindClient(
     const SocketAddress& int_ip) {
   // See if we have the requested IP, or any of our children do.
   return (clients_.find(int_ip) != clients_.end()) ? this
                                                    : nats_.FindClient(int_ip);
 }

 // NATSocketServer::TranslatorMap
 NATSocketServer::TranslatorMap::~TranslatorMap() {
   for (TranslatorMap::iterator it = begin(); it != end(); ++it) {
     delete it->second;
   }
 }

 NATSocketServer::Translator* NATSocketServer::TranslatorMap::Get(
     const SocketAddress& ext_ip) {
   TranslatorMap::iterator it = find(ext_ip);
   return (it != end()) ? it->second : nullptr;
 }

 NATSocketServer::Translator* NATSocketServer::TranslatorMap::Add(
     const SocketAddress& ext_ip,
     Translator* nat) {
   (*this)[ext_ip] = nat;
   return nat;
 }

 void NATSocketServer::TranslatorMap::Remove(const SocketAddress& ext_ip) {
   TranslatorMap::iterator it = find(ext_ip);
   if (it != end()) {
     delete it->second;
     erase(it);
   }
 }

 NATSocketServer::Translator* NATSocketServer::TranslatorMap::FindClient(
     const SocketAddress& int_ip) {
   Translator* nat = nullptr;
   for (TranslatorMap::iterator it = begin(); it != end() && !nat; ++it) {
     nat = it->second->FindClient(int_ip);
   }
   return nat;
 }

 }  // namespace rtc
	/*
	* 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.
	*/

	#include "rtc_base/nat_socket_factory.h"

	#include "rtc_base/arraysize.h"
	#include "rtc_base/checks.h"
	#include "rtc_base/logging.h"
	#include "rtc_base/nat_server.h"
	#include "rtc_base/virtual_socket_server.h"

	namespace rtc {

	// Packs the given socketaddress into the buffer in buf, in the quasi-STUN
	// format that the natserver uses.
	// Returns 0 if an invalid address is passed.
	size_t PackAddressForNAT(char* buf,
	size_t buf_size,
	const SocketAddress& remote_addr) {
	const IPAddress& ip = remote_addr.ipaddr();
	int family = ip.family();
	buf[0] = 0;
	buf[1] = family;
	// Writes the port.
	(reinterpret_cast<uint16_t>(&buf[2])) = HostToNetwork16(remote_addr.port());
	if (family == AF_INET) {
	RTC_DCHECK(buf_size >= kNATEncodedIPv4AddressSize);
	in_addr v4addr = ip.ipv4_address();
	memcpy(&buf[4], &v4addr, kNATEncodedIPv4AddressSize - 4);
	return kNATEncodedIPv4AddressSize;
	} else if (family == AF_INET6) {
	RTC_DCHECK(buf_size >= kNATEncodedIPv6AddressSize);
	in6_addr v6addr = ip.ipv6_address();
	memcpy(&buf[4], &v6addr, kNATEncodedIPv6AddressSize - 4);
	return kNATEncodedIPv6AddressSize;
	}
	return 0U;
	}

	// Decodes the remote address from a packet that has been encoded with the nat's
	// quasi-STUN format. Returns the length of the address (i.e., the offset into
	// data where the original packet starts).
	size_t UnpackAddressFromNAT(const char* buf,
	size_t buf_size,
	SocketAddress* remote_addr) {
	RTC_DCHECK(buf_size >= 8);
	RTC_DCHECK(buf[0] == 0);
	int family = buf[1];
	uint16_t port =
	NetworkToHost16((reinterpret_cast<const uint16_t>(&buf[2])));
	if (family == AF_INET) {
	const in_addr* v4addr = reinterpret_cast<const in_addr*>(&buf[4]);
	remote_addr = SocketAddress(IPAddress(v4addr), port);
	return kNATEncodedIPv4AddressSize;
	} else if (family == AF_INET6) {
	RTC_DCHECK(buf_size >= 20);
	const in6_addr* v6addr = reinterpret_cast<const in6_addr*>(&buf[4]);
	remote_addr = SocketAddress(IPAddress(v6addr), port);
	return kNATEncodedIPv6AddressSize;
	}
	return 0U;
	}

	// NATSocket
	class NATSocket : public AsyncSocket, public sigslot::has_slots<> {
	public:
	explicit NATSocket(NATInternalSocketFactory* sf, int family, int type)
	: sf_(sf),
	family_(family),
	type_(type),
	connected_(false),
	socket_(nullptr),
	buf_(nullptr),
	size_(0) {}

	~NATSocket() override {
	delete socket_;
	delete[] buf_;
	}

	SocketAddress GetLocalAddress() const override {
	return (socket_) ? socket_->GetLocalAddress() : SocketAddress();
	}

	SocketAddress GetRemoteAddress() const override {
	return remote_addr_; // will be NIL if not connected
	}

	int Bind(const SocketAddress& addr) override {
	if (socket_) { // already bound, bubble up error
	return -1;
	}

	return BindInternal(addr);
	}

	int Connect(const SocketAddress& addr) override {
	int result = 0;
	// If we're not already bound (meaning `socket_` is null), bind to ANY
	// address.
	if (!socket_) {
	result = BindInternal(SocketAddress(GetAnyIP(family_), 0));
	if (result < 0) {
	return result;
	}
	}

	if (type_ == SOCK_STREAM) {
	result = socket_->Connect(server_addr_.IsNil() ? addr : server_addr_);
	} else {
	connected_ = true;
	}

	if (result >= 0) {
	remote_addr_ = addr;
	}

	return result;
	}

	int Send(const void* data, size_t size) override {
	RTC_DCHECK(connected_);
	return SendTo(data, size, remote_addr_);
	}

	int SendTo(const void* data,
	size_t size,
	const SocketAddress& addr) override {
	RTC_DCHECK(!connected_ \|\| addr == remote_addr_);
	if (server_addr_.IsNil() \|\| type_ == SOCK_STREAM) {
	return socket_->SendTo(data, size, addr);
	}
	// This array will be too large for IPv4 packets, but only by 12 bytes.
	std::unique_ptr<char[]> buf(new char[size + kNATEncodedIPv6AddressSize]);
	size_t addrlength =
	PackAddressForNAT(buf.get(), size + kNATEncodedIPv6AddressSize, addr);
	size_t encoded_size = size + addrlength;
	memcpy(buf.get() + addrlength, data, size);
	int result = socket_->SendTo(buf.get(), encoded_size, server_addr_);
	if (result >= 0) {
	RTC_DCHECK(result == static_cast<int>(encoded_size));
	result = result - static_cast<int>(addrlength);
	}
	return result;
	}

	int Recv(void* data, size_t size, int64_t* timestamp) override {
	SocketAddress addr;
	return RecvFrom(data, size, &addr, timestamp);
	}

	int RecvFrom(void* data,
	size_t size,
	SocketAddress* out_addr,
	int64_t* timestamp) override {
	if (server_addr_.IsNil() \|\| type_ == SOCK_STREAM) {
	return socket_->RecvFrom(data, size, out_addr, timestamp);
	}
	// Make sure we have enough room to read the requested amount plus the
	// largest possible header address.
	SocketAddress remote_addr;
	Grow(size + kNATEncodedIPv6AddressSize);

	// Read the packet from the socket.
	int result = socket_->RecvFrom(buf_, size_, &remote_addr, timestamp);
	if (result >= 0) {
	RTC_DCHECK(remote_addr == server_addr_);

	// TODO: we need better framing so we know how many bytes we can
	// return before we need to read the next address. For UDP, this will be
	// fine as long as the reader always reads everything in the packet.
	RTC_DCHECK((size_t)result < size_);

	// Decode the wire packet into the actual results.
	SocketAddress real_remote_addr;
	size_t addrlength = UnpackAddressFromNAT(buf_, result, &real_remote_addr);
	memcpy(data, buf_ + addrlength, result - addrlength);

	// Make sure this packet should be delivered before returning it.
	if (!connected_ \|\| (real_remote_addr == remote_addr_)) {
	if (out_addr)
	*out_addr = real_remote_addr;
	result = result - static_cast<int>(addrlength);
	} else {
	RTC_LOG(LS_ERROR) << "Dropping packet from unknown remote address: "
	<< real_remote_addr.ToString();
	result = 0; // Tell the caller we didn't read anything
	}
	}

	return result;
	}

	int Close() override {
	int result = 0;
	if (socket_) {
	result = socket_->Close();
	if (result >= 0) {
	connected_ = false;
	remote_addr_ = SocketAddress();
	delete socket_;
	socket_ = nullptr;
	}
	}
	return result;
	}

	int Listen(int backlog) override { return socket_->Listen(backlog); }
	AsyncSocket* Accept(SocketAddress* paddr) override {
	return socket_->Accept(paddr);
	}
	int GetError() const override {
	return socket_ ? socket_->GetError() : error_;
	}
	void SetError(int error) override {
	if (socket_) {
	socket_->SetError(error);
	} else {
	error_ = error;
	}
	}
	ConnState GetState() const override {
	return connected_ ? CS_CONNECTED : CS_CLOSED;
	}
	int GetOption(Option opt, int* value) override {
	return socket_ ? socket_->GetOption(opt, value) : -1;
	}
	int SetOption(Option opt, int value) override {
	return socket_ ? socket_->SetOption(opt, value) : -1;
	}

	void OnConnectEvent(AsyncSocket* socket) {
	// If we're NATed, we need to send a message with the real addr to use.
	RTC_DCHECK(socket == socket_);
	if (server_addr_.IsNil()) {
	connected_ = true;
	SignalConnectEvent(this);
	} else {
	SendConnectRequest();
	}
	}
	void OnReadEvent(AsyncSocket* socket) {
	// If we're NATed, we need to process the connect reply.
	RTC_DCHECK(socket == socket_);
	if (type_ == SOCK_STREAM && !server_addr_.IsNil() && !connected_) {
	HandleConnectReply();
	} else {
	SignalReadEvent(this);
	}
	}
	void OnWriteEvent(AsyncSocket* socket) {
	RTC_DCHECK(socket == socket_);
	SignalWriteEvent(this);
	}
	void OnCloseEvent(AsyncSocket* socket, int error) {
	RTC_DCHECK(socket == socket_);
	SignalCloseEvent(this, error);
	}

	private:
	int BindInternal(const SocketAddress& addr) {
	RTC_DCHECK(!socket_);

	int result;
	socket_ = sf_->CreateInternalSocket(family_, type_, addr, &server_addr_);
	result = (socket_) ? socket_->Bind(addr) : -1;
	if (result >= 0) {
	socket_->SignalConnectEvent.connect(this, &NATSocket::OnConnectEvent);
	socket_->SignalReadEvent.connect(this, &NATSocket::OnReadEvent);
	socket_->SignalWriteEvent.connect(this, &NATSocket::OnWriteEvent);
	socket_->SignalCloseEvent.connect(this, &NATSocket::OnCloseEvent);
	} else {
	server_addr_.Clear();
	delete socket_;
	socket_ = nullptr;
	}

	return result;
	}

	// Makes sure the buffer is at least the given size.
	void Grow(size_t new_size) {
	if (size_ < new_size) {
	delete[] buf_;
	size_ = new_size;
	buf_ = new char[size_];
	}
	}

	// Sends the destination address to the server to tell it to connect.
	void SendConnectRequest() {
	char buf[kNATEncodedIPv6AddressSize];
	size_t length = PackAddressForNAT(buf, arraysize(buf), remote_addr_);
	socket_->Send(buf, length);
	}

	// Handles the byte sent back from the server and fires the appropriate event.
	void HandleConnectReply() {
	char code;
	socket_->Recv(&code, sizeof(code), nullptr);
	if (code == 0) {
	connected_ = true;
	SignalConnectEvent(this);
	} else {
	Close();
	SignalCloseEvent(this, code);
	}
	}

	NATInternalSocketFactory* sf_;
	int family_;
	int type_;
	bool connected_;
	SocketAddress remote_addr_;
	SocketAddress server_addr_; // address of the NAT server
	AsyncSocket* socket_;
	// Need to hold error in case it occurs before the socket is created.
	int error_ = 0;
	char* buf_;
	size_t size_;
	};

	// NATSocketFactory
	NATSocketFactory::NATSocketFactory(SocketFactory* factory,
	const SocketAddress& nat_udp_addr,
	const SocketAddress& nat_tcp_addr)
	: factory_(factory),
	nat_udp_addr_(nat_udp_addr),
	nat_tcp_addr_(nat_tcp_addr) {}

	Socket* NATSocketFactory::CreateSocket(int family, int type) {
	return new NATSocket(this, family, type);
	}

	AsyncSocket* NATSocketFactory::CreateAsyncSocket(int family, int type) {
	return new NATSocket(this, family, type);
	}

	AsyncSocket* NATSocketFactory::CreateInternalSocket(
	int family,
	int type,
	const SocketAddress& local_addr,
	SocketAddress* nat_addr) {
	if (type == SOCK_STREAM) {
	*nat_addr = nat_tcp_addr_;
	} else {
	*nat_addr = nat_udp_addr_;
	}
	return factory_->CreateAsyncSocket(family, type);
	}

	// NATSocketServer
	NATSocketServer::NATSocketServer(SocketServer* server)
	: server_(server), msg_queue_(nullptr) {}

	NATSocketServer::Translator* NATSocketServer::GetTranslator(
	const SocketAddress& ext_ip) {
	return nats_.Get(ext_ip);
	}

	NATSocketServer::Translator* NATSocketServer::AddTranslator(
	const SocketAddress& ext_ip,
	const SocketAddress& int_ip,
	NATType type) {
	// Fail if a translator already exists with this extternal address.
	if (nats_.Get(ext_ip))
	return nullptr;

	return nats_.Add(ext_ip, new Translator(this, type, int_ip, server_, ext_ip));
	}

	void NATSocketServer::RemoveTranslator(const SocketAddress& ext_ip) {
	nats_.Remove(ext_ip);
	}

	Socket* NATSocketServer::CreateSocket(int family, int type) {
	return new NATSocket(this, family, type);
	}

	AsyncSocket* NATSocketServer::CreateAsyncSocket(int family, int type) {
	return new NATSocket(this, family, type);
	}

	void NATSocketServer::SetMessageQueue(Thread* queue) {
	msg_queue_ = queue;
	server_->SetMessageQueue(queue);
	}

	bool NATSocketServer::Wait(int cms, bool process_io) {
	return server_->Wait(cms, process_io);
	}

	void NATSocketServer::WakeUp() {
	server_->WakeUp();
	}

	AsyncSocket* NATSocketServer::CreateInternalSocket(
	int family,
	int type,
	const SocketAddress& local_addr,
	SocketAddress* nat_addr) {
	AsyncSocket* socket = nullptr;
	Translator* nat = nats_.FindClient(local_addr);
	if (nat) {
	socket = nat->internal_factory()->CreateAsyncSocket(family, type);
	*nat_addr = (type == SOCK_STREAM) ? nat->internal_tcp_address()
	: nat->internal_udp_address();
	} else {
	socket = server_->CreateAsyncSocket(family, type);
	}
	return socket;
	}

	// NATSocketServer::Translator
	NATSocketServer::Translator::Translator(NATSocketServer* server,
	NATType type,
	const SocketAddress& int_ip,
	SocketFactory* ext_factory,
	const SocketAddress& ext_ip)
	: server_(server) {
	// Create a new private network, and a NATServer running on the private
	// network that bridges to the external network. Also tell the private
	// network to use the same message queue as us.
	internal_server_ = std::make_unique<VirtualSocketServer>();
	internal_server_->SetMessageQueue(server_->queue());
	nat_server_ = std::make_unique<NATServer>(
	type, internal_server_.get(), int_ip, int_ip, ext_factory, ext_ip);
	}

	NATSocketServer::Translator::~Translator() {
	internal_server_->SetMessageQueue(nullptr);
	}

	NATSocketServer::Translator* NATSocketServer::Translator::GetTranslator(
	const SocketAddress& ext_ip) {
	return nats_.Get(ext_ip);
	}

	NATSocketServer::Translator* NATSocketServer::Translator::AddTranslator(
	const SocketAddress& ext_ip,
	const SocketAddress& int_ip,
	NATType type) {
	// Fail if a translator already exists with this extternal address.
	if (nats_.Get(ext_ip))
	return nullptr;

	AddClient(ext_ip);
	return nats_.Add(ext_ip,
	new Translator(server_, type, int_ip, server_, ext_ip));
	}
	void NATSocketServer::Translator::RemoveTranslator(
	const SocketAddress& ext_ip) {
	nats_.Remove(ext_ip);
	RemoveClient(ext_ip);
	}

	bool NATSocketServer::Translator::AddClient(const SocketAddress& int_ip) {
	// Fail if a client already exists with this internal address.
	if (clients_.find(int_ip) != clients_.end())
	return false;

	clients_.insert(int_ip);
	return true;
	}

	void NATSocketServer::Translator::RemoveClient(const SocketAddress& int_ip) {
	std::set<SocketAddress>::iterator it = clients_.find(int_ip);
	if (it != clients_.end()) {
	clients_.erase(it);
	}
	}

	NATSocketServer::Translator* NATSocketServer::Translator::FindClient(
	const SocketAddress& int_ip) {
	// See if we have the requested IP, or any of our children do.
	return (clients_.find(int_ip) != clients_.end()) ? this
	: nats_.FindClient(int_ip);
	}

	// NATSocketServer::TranslatorMap
	NATSocketServer::TranslatorMap::~TranslatorMap() {
	for (TranslatorMap::iterator it = begin(); it != end(); ++it) {
	delete it->second;
	}
	}

	NATSocketServer::Translator* NATSocketServer::TranslatorMap::Get(
	const SocketAddress& ext_ip) {
	TranslatorMap::iterator it = find(ext_ip);
	return (it != end()) ? it->second : nullptr;
	}

	NATSocketServer::Translator* NATSocketServer::TranslatorMap::Add(
	const SocketAddress& ext_ip,
	Translator* nat) {
	(*this)[ext_ip] = nat;
	return nat;
	}

	void NATSocketServer::TranslatorMap::Remove(const SocketAddress& ext_ip) {
	TranslatorMap::iterator it = find(ext_ip);
	if (it != end()) {
	delete it->second;
	erase(it);
	}
	}

	NATSocketServer::Translator* NATSocketServer::TranslatorMap::FindClient(
	const SocketAddress& int_ip) {
	Translator* nat = nullptr;
	for (TranslatorMap::iterator it = begin(); it != end() && !nat; ++it) {
	nat = it->second->FindClient(int_ip);
	}
	return nat;
	}

	} // namespace rtc