256 lines
8.0 KiB
C++
256 lines
8.0 KiB
C++
/*
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* Copyright 2004 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "rtc_base/nat_server.h"
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#include <memory>
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#include "rtc_base/checks.h"
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#include "rtc_base/logging.h"
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#include "rtc_base/nat_socket_factory.h"
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#include "rtc_base/socket_adapters.h"
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namespace rtc {
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RouteCmp::RouteCmp(NAT* nat) : symmetric(nat->IsSymmetric()) {}
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size_t RouteCmp::operator()(const SocketAddressPair& r) const {
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size_t h = r.source().Hash();
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if (symmetric)
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h ^= r.destination().Hash();
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return h;
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}
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bool RouteCmp::operator()(const SocketAddressPair& r1,
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const SocketAddressPair& r2) const {
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if (r1.source() < r2.source())
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return true;
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if (r2.source() < r1.source())
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return false;
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if (symmetric && (r1.destination() < r2.destination()))
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return true;
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if (symmetric && (r2.destination() < r1.destination()))
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return false;
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return false;
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}
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AddrCmp::AddrCmp(NAT* nat)
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: use_ip(nat->FiltersIP()), use_port(nat->FiltersPort()) {}
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size_t AddrCmp::operator()(const SocketAddress& a) const {
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size_t h = 0;
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if (use_ip)
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h ^= HashIP(a.ipaddr());
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if (use_port)
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h ^= a.port() | (a.port() << 16);
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return h;
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}
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bool AddrCmp::operator()(const SocketAddress& a1,
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const SocketAddress& a2) const {
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if (use_ip && (a1.ipaddr() < a2.ipaddr()))
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return true;
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if (use_ip && (a2.ipaddr() < a1.ipaddr()))
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return false;
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if (use_port && (a1.port() < a2.port()))
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return true;
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if (use_port && (a2.port() < a1.port()))
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return false;
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return false;
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}
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// Proxy socket that will capture the external destination address intended for
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// a TCP connection to the NAT server.
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class NATProxyServerSocket : public AsyncProxyServerSocket {
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public:
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NATProxyServerSocket(Socket* socket)
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: AsyncProxyServerSocket(socket, kNATEncodedIPv6AddressSize) {
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BufferInput(true);
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}
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void SendConnectResult(int err, const SocketAddress& addr) override {
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char code = err ? 1 : 0;
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BufferedReadAdapter::DirectSend(&code, sizeof(char));
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}
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protected:
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void ProcessInput(char* data, size_t* len) override {
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if (*len < 2) {
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return;
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}
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int family = data[1];
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RTC_DCHECK(family == AF_INET || family == AF_INET6);
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if ((family == AF_INET && *len < kNATEncodedIPv4AddressSize) ||
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(family == AF_INET6 && *len < kNATEncodedIPv6AddressSize)) {
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return;
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}
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SocketAddress dest_addr;
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size_t address_length = UnpackAddressFromNAT(data, *len, &dest_addr);
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*len -= address_length;
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if (*len > 0) {
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memmove(data, data + address_length, *len);
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}
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bool remainder = (*len > 0);
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BufferInput(false);
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SignalConnectRequest(this, dest_addr);
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if (remainder) {
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SignalReadEvent(this);
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}
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}
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};
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class NATProxyServer : public ProxyServer {
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public:
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NATProxyServer(SocketFactory* int_factory,
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const SocketAddress& int_addr,
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SocketFactory* ext_factory,
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const SocketAddress& ext_ip)
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: ProxyServer(int_factory, int_addr, ext_factory, ext_ip) {}
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protected:
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AsyncProxyServerSocket* WrapSocket(Socket* socket) override {
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return new NATProxyServerSocket(socket);
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}
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};
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NATServer::NATServer(NATType type,
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SocketFactory* internal,
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const SocketAddress& internal_udp_addr,
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const SocketAddress& internal_tcp_addr,
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SocketFactory* external,
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const SocketAddress& external_ip)
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: external_(external), external_ip_(external_ip.ipaddr(), 0) {
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nat_ = NAT::Create(type);
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udp_server_socket_ = AsyncUDPSocket::Create(internal, internal_udp_addr);
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udp_server_socket_->SignalReadPacket.connect(this,
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&NATServer::OnInternalUDPPacket);
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tcp_proxy_server_ =
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new NATProxyServer(internal, internal_tcp_addr, external, external_ip);
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int_map_ = new InternalMap(RouteCmp(nat_));
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ext_map_ = new ExternalMap();
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}
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NATServer::~NATServer() {
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for (InternalMap::iterator iter = int_map_->begin(); iter != int_map_->end();
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iter++)
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delete iter->second;
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delete nat_;
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delete udp_server_socket_;
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delete tcp_proxy_server_;
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delete int_map_;
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delete ext_map_;
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}
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void NATServer::OnInternalUDPPacket(AsyncPacketSocket* socket,
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const char* buf,
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size_t size,
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const SocketAddress& addr,
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const int64_t& /* packet_time_us */) {
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// Read the intended destination from the wire.
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SocketAddress dest_addr;
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size_t length = UnpackAddressFromNAT(buf, size, &dest_addr);
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// Find the translation for these addresses (allocating one if necessary).
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SocketAddressPair route(addr, dest_addr);
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InternalMap::iterator iter = int_map_->find(route);
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if (iter == int_map_->end()) {
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Translate(route);
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iter = int_map_->find(route);
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}
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RTC_DCHECK(iter != int_map_->end());
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// Allow the destination to send packets back to the source.
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iter->second->AllowlistInsert(dest_addr);
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// Send the packet to its intended destination.
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rtc::PacketOptions options;
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iter->second->socket->SendTo(buf + length, size - length, dest_addr, options);
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}
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void NATServer::OnExternalUDPPacket(AsyncPacketSocket* socket,
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const char* buf,
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size_t size,
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const SocketAddress& remote_addr,
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const int64_t& /* packet_time_us */) {
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SocketAddress local_addr = socket->GetLocalAddress();
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// Find the translation for this addresses.
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ExternalMap::iterator iter = ext_map_->find(local_addr);
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RTC_DCHECK(iter != ext_map_->end());
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// Allow the NAT to reject this packet.
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if (ShouldFilterOut(iter->second, remote_addr)) {
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RTC_LOG(LS_INFO) << "Packet from " << remote_addr.ToSensitiveString()
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<< " was filtered out by the NAT.";
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return;
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}
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// Forward this packet to the internal address.
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// First prepend the address in a quasi-STUN format.
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std::unique_ptr<char[]> real_buf(new char[size + kNATEncodedIPv6AddressSize]);
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size_t addrlength = PackAddressForNAT(
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real_buf.get(), size + kNATEncodedIPv6AddressSize, remote_addr);
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// Copy the data part after the address.
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rtc::PacketOptions options;
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memcpy(real_buf.get() + addrlength, buf, size);
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udp_server_socket_->SendTo(real_buf.get(), size + addrlength,
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iter->second->route.source(), options);
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}
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void NATServer::Translate(const SocketAddressPair& route) {
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AsyncUDPSocket* socket = AsyncUDPSocket::Create(external_, external_ip_);
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if (!socket) {
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RTC_LOG(LS_ERROR) << "Couldn't find a free port!";
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return;
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}
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TransEntry* entry = new TransEntry(route, socket, nat_);
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(*int_map_)[route] = entry;
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(*ext_map_)[socket->GetLocalAddress()] = entry;
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socket->SignalReadPacket.connect(this, &NATServer::OnExternalUDPPacket);
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}
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bool NATServer::ShouldFilterOut(TransEntry* entry,
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const SocketAddress& ext_addr) {
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return entry->AllowlistContains(ext_addr);
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}
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NATServer::TransEntry::TransEntry(const SocketAddressPair& r,
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AsyncUDPSocket* s,
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NAT* nat)
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: route(r), socket(s) {
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allowlist = new AddressSet(AddrCmp(nat));
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}
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NATServer::TransEntry::~TransEntry() {
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delete allowlist;
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delete socket;
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}
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void NATServer::TransEntry::AllowlistInsert(const SocketAddress& addr) {
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webrtc::MutexLock lock(&mutex_);
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allowlist->insert(addr);
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}
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bool NATServer::TransEntry::AllowlistContains(const SocketAddress& ext_addr) {
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webrtc::MutexLock lock(&mutex_);
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return allowlist->find(ext_addr) == allowlist->end();
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}
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} // namespace rtc
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