text: /*
   * libjingle
   * Copyright 2004--2005, Google Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *  1. Redistributions of source code must retain the above copyright notice,
   *     this list of conditions and the following disclaimer.
   *  2. Redistributions in binary form must reproduce the above copyright notice,
   *     this list of conditions and the following disclaimer in the documentation
   *     and/or other materials provided with the distribution.
   *  3. The name of the author may not be used to endorse or promote products
   *     derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
   * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "talk/base/natsocketfactory.h"
  #include "talk/base/natserver.h"
  #include "talk/base/logging.h"
  
  namespace talk_base {
  
  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;
  }
  
  NATServer::NATServer(
      NATType type, SocketFactory* internal, const SocketAddress& internal_addr,
      SocketFactory* external, const SocketAddress& external_ip)
      : external_(external), external_ip_(external_ip.ipaddr(), 0) {
    nat_ = NAT::Create(type);
  
    server_socket_ = AsyncUDPSocket::Create(internal, internal_addr);
    server_socket_->SignalReadPacket.connect(this, &NATServer::OnInternalPacket);
  
    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 server_socket_;
    delete int_map_;
    delete ext_map_;
  }
  
  void NATServer::OnInternalPacket(
      AsyncPacketSocket* socket, const char* buf, size_t size,
      const SocketAddress& addr) {
  
    // Read the intended destination from the wire.
    SocketAddress dest_addr;
    int 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);
    }
    ASSERT(iter != int_map_->end());
  
    // Allow the destination to send packets back to the source.
    iter->second->whitelist->insert(dest_addr);
  
    // Send the packet to its intended destination.
    iter->second->socket->SendTo(buf + length, size - length, dest_addr);
  }
  
  void NATServer::OnExternalPacket(
      AsyncPacketSocket* socket, const char* buf, size_t size,
      const SocketAddress& remote_addr) {
  
    SocketAddress local_addr = socket->GetLocalAddress();
  
    // Find the translation for this addresses.
    ExternalMap::iterator iter = ext_map_->find(local_addr);
    ASSERT(iter != ext_map_->end());
  
    // Allow the NAT to reject this packet.
    if (Filter(iter->second, remote_addr)) {
      LOG(LS_INFO) << "Packet from " << remote_addr.ToString()
                   << " was filtered out by the NAT.";
      return;
    }
  
    // Forward this packet to the internal address.
    // First prepend the address in a quasi-STUN format.
    scoped_array<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.
    std::memcpy(real_buf.get() + addrlength, buf, size);
    server_socket_->SendTo(real_buf.get(), size + addrlength,
                           iter->second->route.source());
  }
  
  void NATServer::Translate(const SocketAddressPair& route) {
    AsyncUDPSocket* socket = AsyncUDPSocket::Create(external_, external_ip_);
  
    if (!socket) {
      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::OnExternalPacket);
  }
  
  bool NATServer::Filter(TransEntry* entry, const SocketAddress& ext_addr) {
    return entry->whitelist->find(ext_addr) == entry->whitelist->end();
  }
  
  NATServer::TransEntry::TransEntry(
      const SocketAddressPair& r, AsyncUDPSocket* s, NAT* nat)
      : route(r), socket(s) {
    whitelist = new AddressSet(AddrCmp(nat));
  }
  
  NATServer::TransEntry::~TransEntry() {
    delete whitelist;
    delete socket;
  }
  
  }  // namespace talk_base
  