rtc_base/nat_server.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_server.h"

 #include <cstddef>
 #include <cstdint>
 #include <memory>

 #include "api/array_view.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/nat_socket_factory.h"
 #include "rtc_base/network/received_packet.h"
 #include "rtc_base/socket_adapters.h"
 #include "rtc_base/socket_address.h"

 namespace rtc {

 RouteCmp::RouteCmp(NAT* nat) : symmetric(nat->IsSymmetric()) {}

 size_t RouteCmp::operator()(const SocketAddressPair& r) const {
   size_t h = r.source().Hash();
   if (symmetric)
     h ^= r.destination().Hash();
   return h;
 }

 bool RouteCmp::operator()(const SocketAddressPair& r1,
                           const SocketAddressPair& r2) const {
   if (r1.source() < r2.source())
     return true;
   if (r2.source() < r1.source())
     return false;
   if (symmetric && (r1.destination() < r2.destination()))
     return true;
   if (symmetric && (r2.destination() < r1.destination()))
     return false;
   return false;
 }

 AddrCmp::AddrCmp(NAT* nat)
     : use_ip(nat->FiltersIP()), use_port(nat->FiltersPort()) {}

 size_t AddrCmp::operator()(const SocketAddress& a) const {
   size_t h = 0;
   if (use_ip)
     h ^= HashIP(a.ipaddr());
   if (use_port)
     h ^= a.port() | (a.port() << 16);
   return h;
 }

 bool AddrCmp::operator()(const SocketAddress& a1,
                          const SocketAddress& a2) const {
   if (use_ip && (a1.ipaddr() < a2.ipaddr()))
     return true;
   if (use_ip && (a2.ipaddr() < a1.ipaddr()))
     return false;
   if (use_port && (a1.port() < a2.port()))
     return true;
   if (use_port && (a2.port() < a1.port()))
     return false;
   return false;
 }

 // Proxy socket that will capture the external destination address intended for
 // a TCP connection to the NAT server.
 class NATProxyServerSocket : public AsyncProxyServerSocket {
  public:
   NATProxyServerSocket(Socket* socket)
       : AsyncProxyServerSocket(socket, kNATEncodedIPv6AddressSize) {
     BufferInput(true);
   }

   void SendConnectResult(int err, const SocketAddress& addr) override {
     char code = err ? 1 : 0;
     BufferedReadAdapter::DirectSend(&code, sizeof(char));
   }

  protected:
   void ProcessInput(char* data, size_t* len) override {
     if (*len < 2) {
       return;
     }

     int family = data[1];
     RTC_DCHECK(family == AF_INET || family == AF_INET6);
     if ((family == AF_INET && *len < kNATEncodedIPv4AddressSize) ||
         (family == AF_INET6 && *len < kNATEncodedIPv6AddressSize)) {
       return;
     }

     SocketAddress dest_addr;
     size_t address_length = UnpackAddressFromNAT(
         MakeArrayView(reinterpret_cast<const uint8_t*>(data), *len),
         &dest_addr);
     *len -= address_length;
     if (*len > 0) {
       memmove(data, data + address_length, *len);
     }

     bool remainder = (*len > 0);
     BufferInput(false);
     SignalConnectRequest(this, dest_addr);
     if (remainder) {
       SignalReadEvent(this);
     }
   }
 };

 class NATProxyServer : public ProxyServer {
  public:
   NATProxyServer(SocketFactory* int_factory,
                  const SocketAddress& int_addr,
                  SocketFactory* ext_factory,
                  const SocketAddress& ext_ip)
       : ProxyServer(int_factory, int_addr, ext_factory, ext_ip) {}

  protected:
   AsyncProxyServerSocket* WrapSocket(Socket* socket) override {
     return new NATProxyServerSocket(socket);
   }
 };

 NATServer::NATServer(NATType type,
                      rtc::Thread& internal_socket_thread,
                      SocketFactory* internal,
                      const SocketAddress& internal_udp_addr,
                      const SocketAddress& internal_tcp_addr,
                      rtc::Thread& external_socket_thread,
                      SocketFactory* external,
                      const SocketAddress& external_ip)
     : internal_socket_thread_(internal_socket_thread),
       external_socket_thread_(external_socket_thread),
       external_(external),
       external_ip_(external_ip.ipaddr(), 0) {
   nat_ = NAT::Create(type);

   internal_socket_thread_.BlockingCall([&] {
     udp_server_socket_ = AsyncUDPSocket::Create(internal, internal_udp_addr);
     udp_server_socket_->RegisterReceivedPacketCallback(
         [&](rtc::AsyncPacketSocket* socket, const rtc::ReceivedPacket& packet) {
           OnInternalUDPPacket(socket, packet);
         });
   });

   tcp_proxy_server_ =
       new NATProxyServer(internal, internal_tcp_addr, external, external_ip);

   int_map_ = new InternalMap(RouteCmp(nat_));
   ext_map_ = new ExternalMap();
 }

 NATServer::~NATServer() {
   for (InternalMap::iterator iter = int_map_->begin(); iter != int_map_->end();
        iter++)
     delete iter->second;

   delete nat_;
   delete udp_server_socket_;
   delete tcp_proxy_server_;
   delete int_map_;
   delete ext_map_;
 }

 void NATServer::OnInternalUDPPacket(AsyncPacketSocket* socket,
                                     const rtc::ReceivedPacket& packet) {
   RTC_DCHECK(internal_socket_thread_.IsCurrent());
   // Read the intended destination from the wire.
   SocketAddress dest_addr;
   size_t length = UnpackAddressFromNAT(packet.payload(), &dest_addr);

   // Find the translation for these addresses (allocating one if necessary).
   SocketAddressPair route(packet.source_address(), dest_addr);
   InternalMap::iterator iter = int_map_->find(route);
   if (iter == int_map_->end()) {
     Translate(route);
     iter = int_map_->find(route);
   }
   RTC_DCHECK(iter != int_map_->end());

   // Allow the destination to send packets back to the source.
   iter->second->AllowlistInsert(dest_addr);

   // Send the packet to its intended destination.
   rtc::PacketOptions options;
   const char* buf = reinterpret_cast<const char*>(packet.payload().data());
   size_t size = packet.payload().size();
   iter->second->socket->SendTo(buf + length, size - length, dest_addr, options);
 }

 void NATServer::OnExternalUDPPacket(AsyncPacketSocket* socket,
                                     const rtc::ReceivedPacket& packet) {
   RTC_DCHECK(external_socket_thread_.IsCurrent());
   SocketAddress local_addr = socket->GetLocalAddress();

   // Find the translation for this addresses.
   ExternalMap::iterator iter = ext_map_->find(local_addr);
   RTC_DCHECK(iter != ext_map_->end());

   // Allow the NAT to reject this packet.
   if (ShouldFilterOut(iter->second, packet.source_address())) {
     RTC_LOG(LS_INFO) << "Packet from "
                      << packet.source_address().ToSensitiveString()
                      << " was filtered out by the NAT.";
     return;
   }

   // Forward this packet to the internal address.
   // First prepend the address in a quasi-STUN format.
   std::unique_ptr<char[]> real_buf(
       new char[packet.payload().size() + kNATEncodedIPv6AddressSize]);
   size_t addrlength = PackAddressForNAT(
       real_buf.get(), packet.payload().size() + kNATEncodedIPv6AddressSize,
       packet.source_address());
   // Copy the data part after the address.
   rtc::PacketOptions options;
   memcpy(real_buf.get() + addrlength, packet.payload().data(),
          packet.payload().size());
   udp_server_socket_->SendTo(real_buf.get(),
                              packet.payload().size() + addrlength,
                              iter->second->route.source(), options);
 }

 void NATServer::Translate(const SocketAddressPair& route) {
   external_socket_thread_.BlockingCall([&] {
     AsyncUDPSocket* socket = AsyncUDPSocket::Create(external_, external_ip_);

     if (!socket) {
       RTC_LOG(LS_ERROR) << "Couldn't find a free port!";
       return;
     }

     TransEntry* entry = new TransEntry(route, socket, nat_);
     (*int_map_)[route] = entry;
     (*ext_map_)[socket->GetLocalAddress()] = entry;
     socket->RegisterReceivedPacketCallback(
         [&](rtc::AsyncPacketSocket* socket, const rtc::ReceivedPacket& packet) {
           OnExternalUDPPacket(socket, packet);
         });
   });
 }

 bool NATServer::ShouldFilterOut(TransEntry* entry,
                                 const SocketAddress& ext_addr) {
   return entry->AllowlistContains(ext_addr);
 }

 NATServer::TransEntry::TransEntry(const SocketAddressPair& r,
                                   AsyncUDPSocket* s,
                                   NAT* nat)
     : route(r), socket(s) {
   allowlist = new AddressSet(AddrCmp(nat));
 }

 NATServer::TransEntry::~TransEntry() {
   delete allowlist;
   delete socket;
 }

 void NATServer::TransEntry::AllowlistInsert(const SocketAddress& addr) {
   webrtc::MutexLock lock(&mutex_);
   allowlist->insert(addr);
 }

 bool NATServer::TransEntry::AllowlistContains(const SocketAddress& ext_addr) {
   webrtc::MutexLock lock(&mutex_);
   return allowlist->find(ext_addr) == allowlist->end();
 }

 }  // 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_server.h"

	#include <cstddef>
	#include <cstdint>
	#include <memory>

	#include "api/array_view.h"
	#include "rtc_base/checks.h"
	#include "rtc_base/logging.h"
	#include "rtc_base/nat_socket_factory.h"
	#include "rtc_base/network/received_packet.h"
	#include "rtc_base/socket_adapters.h"
	#include "rtc_base/socket_address.h"

	namespace rtc {

	RouteCmp::RouteCmp(NAT* nat) : symmetric(nat->IsSymmetric()) {}

	size_t RouteCmp::operator()(const SocketAddressPair& r) const {
	size_t h = r.source().Hash();
	if (symmetric)
	h ^= r.destination().Hash();
	return h;
	}

	bool RouteCmp::operator()(const SocketAddressPair& r1,
	const SocketAddressPair& r2) const {
	if (r1.source() < r2.source())
	return true;
	if (r2.source() < r1.source())
	return false;
	if (symmetric && (r1.destination() < r2.destination()))
	return true;
	if (symmetric && (r2.destination() < r1.destination()))
	return false;
	return false;
	}

	AddrCmp::AddrCmp(NAT* nat)
	: use_ip(nat->FiltersIP()), use_port(nat->FiltersPort()) {}

	size_t AddrCmp::operator()(const SocketAddress& a) const {
	size_t h = 0;
	if (use_ip)
	h ^= HashIP(a.ipaddr());
	if (use_port)
	h ^= a.port() \| (a.port() << 16);
	return h;
	}

	bool AddrCmp::operator()(const SocketAddress& a1,
	const SocketAddress& a2) const {
	if (use_ip && (a1.ipaddr() < a2.ipaddr()))
	return true;
	if (use_ip && (a2.ipaddr() < a1.ipaddr()))
	return false;
	if (use_port && (a1.port() < a2.port()))
	return true;
	if (use_port && (a2.port() < a1.port()))
	return false;
	return false;
	}

	// Proxy socket that will capture the external destination address intended for
	// a TCP connection to the NAT server.
	class NATProxyServerSocket : public AsyncProxyServerSocket {
	public:
	NATProxyServerSocket(Socket* socket)
	: AsyncProxyServerSocket(socket, kNATEncodedIPv6AddressSize) {
	BufferInput(true);
	}

	void SendConnectResult(int err, const SocketAddress& addr) override {
	char code = err ? 1 : 0;
	BufferedReadAdapter::DirectSend(&code, sizeof(char));
	}

	protected:
	void ProcessInput(char* data, size_t* len) override {
	if (*len < 2) {
	return;
	}

	int family = data[1];
	RTC_DCHECK(family == AF_INET \|\| family == AF_INET6);
	if ((family == AF_INET && *len < kNATEncodedIPv4AddressSize) \|\|
	(family == AF_INET6 && *len < kNATEncodedIPv6AddressSize)) {
	return;
	}

	SocketAddress dest_addr;
	size_t address_length = UnpackAddressFromNAT(
	MakeArrayView(reinterpret_cast<const uint8_t>(data), len),
	&dest_addr);
	*len -= address_length;
	if (*len > 0) {
	memmove(data, data + address_length, *len);
	}

	bool remainder = (*len > 0);
	BufferInput(false);
	SignalConnectRequest(this, dest_addr);
	if (remainder) {
	SignalReadEvent(this);
	}
	}
	};

	class NATProxyServer : public ProxyServer {
	public:
	NATProxyServer(SocketFactory* int_factory,
	const SocketAddress& int_addr,
	SocketFactory* ext_factory,
	const SocketAddress& ext_ip)
	: ProxyServer(int_factory, int_addr, ext_factory, ext_ip) {}

	protected:
	AsyncProxyServerSocket* WrapSocket(Socket* socket) override {
	return new NATProxyServerSocket(socket);
	}
	};

	NATServer::NATServer(NATType type,
	rtc::Thread& internal_socket_thread,
	SocketFactory* internal,
	const SocketAddress& internal_udp_addr,
	const SocketAddress& internal_tcp_addr,
	rtc::Thread& external_socket_thread,
	SocketFactory* external,
	const SocketAddress& external_ip)
	: internal_socket_thread_(internal_socket_thread),
	external_socket_thread_(external_socket_thread),
	external_(external),
	external_ip_(external_ip.ipaddr(), 0) {
	nat_ = NAT::Create(type);

	internal_socket_thread_.BlockingCall([&] {
	udp_server_socket_ = AsyncUDPSocket::Create(internal, internal_udp_addr);
	udp_server_socket_->RegisterReceivedPacketCallback(
	[&](rtc::AsyncPacketSocket* socket, const rtc::ReceivedPacket& packet) {
	OnInternalUDPPacket(socket, packet);
	});
	});

	tcp_proxy_server_ =
	new NATProxyServer(internal, internal_tcp_addr, external, external_ip);

	int_map_ = new InternalMap(RouteCmp(nat_));
	ext_map_ = new ExternalMap();
	}

	NATServer::~NATServer() {
	for (InternalMap::iterator iter = int_map_->begin(); iter != int_map_->end();
	iter++)
	delete iter->second;

	delete nat_;
	delete udp_server_socket_;
	delete tcp_proxy_server_;
	delete int_map_;
	delete ext_map_;
	}

	void NATServer::OnInternalUDPPacket(AsyncPacketSocket* socket,
	const rtc::ReceivedPacket& packet) {
	RTC_DCHECK(internal_socket_thread_.IsCurrent());
	// Read the intended destination from the wire.
	SocketAddress dest_addr;
	size_t length = UnpackAddressFromNAT(packet.payload(), &dest_addr);

	// Find the translation for these addresses (allocating one if necessary).
	SocketAddressPair route(packet.source_address(), dest_addr);
	InternalMap::iterator iter = int_map_->find(route);
	if (iter == int_map_->end()) {
	Translate(route);
	iter = int_map_->find(route);
	}
	RTC_DCHECK(iter != int_map_->end());

	// Allow the destination to send packets back to the source.
	iter->second->AllowlistInsert(dest_addr);

	// Send the packet to its intended destination.
	rtc::PacketOptions options;
	const char* buf = reinterpret_cast<const char*>(packet.payload().data());
	size_t size = packet.payload().size();
	iter->second->socket->SendTo(buf + length, size - length, dest_addr, options);
	}

	void NATServer::OnExternalUDPPacket(AsyncPacketSocket* socket,
	const rtc::ReceivedPacket& packet) {
	RTC_DCHECK(external_socket_thread_.IsCurrent());
	SocketAddress local_addr = socket->GetLocalAddress();

	// Find the translation for this addresses.
	ExternalMap::iterator iter = ext_map_->find(local_addr);
	RTC_DCHECK(iter != ext_map_->end());

	// Allow the NAT to reject this packet.
	if (ShouldFilterOut(iter->second, packet.source_address())) {
	RTC_LOG(LS_INFO) << "Packet from "
	<< packet.source_address().ToSensitiveString()
	<< " was filtered out by the NAT.";
	return;
	}

	// Forward this packet to the internal address.
	// First prepend the address in a quasi-STUN format.
	std::unique_ptr<char[]> real_buf(
	new char[packet.payload().size() + kNATEncodedIPv6AddressSize]);
	size_t addrlength = PackAddressForNAT(
	real_buf.get(), packet.payload().size() + kNATEncodedIPv6AddressSize,
	packet.source_address());
	// Copy the data part after the address.
	rtc::PacketOptions options;
	memcpy(real_buf.get() + addrlength, packet.payload().data(),
	packet.payload().size());
	udp_server_socket_->SendTo(real_buf.get(),
	packet.payload().size() + addrlength,
	iter->second->route.source(), options);
	}

	void NATServer::Translate(const SocketAddressPair& route) {
	external_socket_thread_.BlockingCall([&] {
	AsyncUDPSocket* socket = AsyncUDPSocket::Create(external_, external_ip_);

	if (!socket) {
	RTC_LOG(LS_ERROR) << "Couldn't find a free port!";
	return;
	}

	TransEntry* entry = new TransEntry(route, socket, nat_);
	(*int_map_)[route] = entry;
	(*ext_map_)[socket->GetLocalAddress()] = entry;
	socket->RegisterReceivedPacketCallback(
	[&](rtc::AsyncPacketSocket* socket, const rtc::ReceivedPacket& packet) {
	OnExternalUDPPacket(socket, packet);
	});
	});
	}

	bool NATServer::ShouldFilterOut(TransEntry* entry,
	const SocketAddress& ext_addr) {
	return entry->AllowlistContains(ext_addr);
	}

	NATServer::TransEntry::TransEntry(const SocketAddressPair& r,
	AsyncUDPSocket* s,
	NAT* nat)
	: route(r), socket(s) {
	allowlist = new AddressSet(AddrCmp(nat));
	}

	NATServer::TransEntry::~TransEntry() {
	delete allowlist;
	delete socket;
	}

	void NATServer::TransEntry::AllowlistInsert(const SocketAddress& addr) {
	webrtc::MutexLock lock(&mutex_);
	allowlist->insert(addr);
	}

	bool NATServer::TransEntry::AllowlistContains(const SocketAddress& ext_addr) {
	webrtc::MutexLock lock(&mutex_);
	return allowlist->find(ext_addr) == allowlist->end();
	}

	} // namespace rtc