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      1 /*
      2  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_BASE_NATSERVER_H_
     12 #define WEBRTC_BASE_NATSERVER_H_
     13 
     14 #include <map>
     15 #include <set>
     16 
     17 #include "webrtc/base/asyncudpsocket.h"
     18 #include "webrtc/base/socketaddresspair.h"
     19 #include "webrtc/base/thread.h"
     20 #include "webrtc/base/socketfactory.h"
     21 #include "webrtc/base/nattypes.h"
     22 
     23 namespace rtc {
     24 
     25 // Change how routes (socketaddress pairs) are compared based on the type of
     26 // NAT.  The NAT server maintains a hashtable of the routes that it knows
     27 // about.  So these affect which routes are treated the same.
     28 struct RouteCmp {
     29   explicit RouteCmp(NAT* nat);
     30   size_t operator()(const SocketAddressPair& r) const;
     31   bool operator()(
     32       const SocketAddressPair& r1, const SocketAddressPair& r2) const;
     33 
     34   bool symmetric;
     35 };
     36 
     37 // Changes how addresses are compared based on the filtering rules of the NAT.
     38 struct AddrCmp {
     39   explicit AddrCmp(NAT* nat);
     40   size_t operator()(const SocketAddress& r) const;
     41   bool operator()(const SocketAddress& r1, const SocketAddress& r2) const;
     42 
     43   bool use_ip;
     44   bool use_port;
     45 };
     46 
     47 // Implements the NAT device.  It listens for packets on the internal network,
     48 // translates them, and sends them out over the external network.
     49 
     50 const int NAT_SERVER_PORT = 4237;
     51 
     52 class NATServer : public sigslot::has_slots<> {
     53  public:
     54   NATServer(
     55       NATType type, SocketFactory* internal, const SocketAddress& internal_addr,
     56       SocketFactory* external, const SocketAddress& external_ip);
     57   ~NATServer();
     58 
     59   SocketAddress internal_address() const {
     60     return server_socket_->GetLocalAddress();
     61   }
     62 
     63   // Packets received on one of the networks.
     64   void OnInternalPacket(AsyncPacketSocket* socket, const char* buf,
     65                         size_t size, const SocketAddress& addr,
     66                         const PacketTime& packet_time);
     67   void OnExternalPacket(AsyncPacketSocket* socket, const char* buf,
     68                         size_t size, const SocketAddress& remote_addr,
     69                         const PacketTime& packet_time);
     70 
     71  private:
     72   typedef std::set<SocketAddress, AddrCmp> AddressSet;
     73 
     74   /* Records a translation and the associated external socket. */
     75   struct TransEntry {
     76     TransEntry(const SocketAddressPair& r, AsyncUDPSocket* s, NAT* nat);
     77     ~TransEntry();
     78 
     79     void WhitelistInsert(const SocketAddress& addr);
     80     bool WhitelistContains(const SocketAddress& ext_addr);
     81 
     82     SocketAddressPair route;
     83     AsyncUDPSocket* socket;
     84     AddressSet* whitelist;
     85     CriticalSection crit_;
     86   };
     87 
     88   typedef std::map<SocketAddressPair, TransEntry*, RouteCmp> InternalMap;
     89   typedef std::map<SocketAddress, TransEntry*> ExternalMap;
     90 
     91   /* Creates a new entry that translates the given route. */
     92   void Translate(const SocketAddressPair& route);
     93 
     94   /* Determines whether the NAT would filter out a packet from this address. */
     95   bool ShouldFilterOut(TransEntry* entry, const SocketAddress& ext_addr);
     96 
     97   NAT* nat_;
     98   SocketFactory* internal_;
     99   SocketFactory* external_;
    100   SocketAddress external_ip_;
    101   AsyncUDPSocket* server_socket_;
    102   AsyncSocket* tcp_server_socket_;
    103   InternalMap* int_map_;
    104   ExternalMap* ext_map_;
    105   DISALLOW_EVIL_CONSTRUCTORS(NATServer);
    106 };
    107 
    108 }  // namespace rtc
    109 
    110 #endif  // WEBRTC_BASE_NATSERVER_H_
    111