1 files changed, 255 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/nat_server.cc b/third_party/libwebrtc/rtc_base/nat_server.cc
new file mode 100644
index 0000000000..b818685efb
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/nat_server.cc
@@ -0,0 +1,255 @@
+/*
+ *  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 <memory>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/nat_socket_factory.h"
+#include "rtc_base/socket_adapters.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(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,
+                     SocketFactory* internal,
+                     const SocketAddress& internal_udp_addr,
+                     const SocketAddress& internal_tcp_addr,
+                     SocketFactory* external,
+                     const SocketAddress& external_ip)
+    : external_(external), external_ip_(external_ip.ipaddr(), 0) {
+  nat_ = NAT::Create(type);
+
+  udp_server_socket_ = AsyncUDPSocket::Create(internal, internal_udp_addr);
+  udp_server_socket_->SignalReadPacket.connect(this,
+                                               &NATServer::OnInternalUDPPacket);
+  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 char* buf,
+                                    size_t size,
+                                    const SocketAddress& addr,
+                                    const int64_t& /* packet_time_us */) {
+  // Read the intended destination from the wire.
+  SocketAddress dest_addr;
+  size_t length = UnpackAddressFromNAT(buf, size, &dest_addr);
+
+  // Find the translation for these addresses (allocating one if necessary).
+  SocketAddressPair route(addr, 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;
+  iter->second->socket->SendTo(buf + length, size - length, dest_addr, options);
+}
+
+void NATServer::OnExternalUDPPacket(AsyncPacketSocket* socket,
+                                    const char* buf,
+                                    size_t size,
+                                    const SocketAddress& remote_addr,
+                                    const int64_t& /* packet_time_us */) {
+  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, remote_addr)) {
+    RTC_LOG(LS_INFO) << "Packet from " << remote_addr.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[size + kNATEncodedIPv6AddressSize]);
+  size_t addrlength = PackAddressForNAT(
+      real_buf.get(), size + kNATEncodedIPv6AddressSize, remote_addr);
+  // Copy the data part after the address.
+  rtc::PacketOptions options;
+  memcpy(real_buf.get() + addrlength, buf, size);
+  udp_server_socket_->SendTo(real_buf.get(), size + addrlength,
+                             iter->second->route.source(), options);
+}
+
+void NATServer::Translate(const SocketAddressPair& route) {
+  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->SignalReadPacket.connect(this, &NATServer::OnExternalUDPPacket);
+}
+
+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