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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 #include "webrtc/base/proxyserver.h"
     23 
     24 namespace rtc {
     25 
     26 // Change how routes (socketaddress pairs) are compared based on the type of
     27 // NAT.  The NAT server maintains a hashtable of the routes that it knows
     28 // about.  So these affect which routes are treated the same.
     29 struct RouteCmp {
     30   explicit RouteCmp(NAT* nat);
     31   size_t operator()(const SocketAddressPair& r) const;
     32   bool operator()(
     33       const SocketAddressPair& r1, const SocketAddressPair& r2) const;
     34 
     35   bool symmetric;
     36 };
     37 
     38 // Changes how addresses are compared based on the filtering rules of the NAT.
     39 struct AddrCmp {
     40   explicit AddrCmp(NAT* nat);
     41   size_t operator()(const SocketAddress& r) const;
     42   bool operator()(const SocketAddress& r1, const SocketAddress& r2) const;
     43 
     44   bool use_ip;
     45   bool use_port;
     46 };
     47 
     48 // Implements the NAT device.  It listens for packets on the internal network,
     49 // translates them, and sends them out over the external network.
     50 //
     51 // TCP connections initiated from the internal side of the NAT server are
     52 // also supported, by making a connection to the NAT server's TCP address and
     53 // then sending the remote address in quasi-STUN format. The connection status
     54 // will be indicated back to the client as a 1 byte status code, where '0'
     55 // indicates success.
     56 
     57 const int NAT_SERVER_UDP_PORT = 4237;
     58 const int NAT_SERVER_TCP_PORT = 4238;
     59 
     60 class NATServer : public sigslot::has_slots<> {
     61  public:
     62   NATServer(
     63       NATType type, SocketFactory* internal,
     64       const SocketAddress& internal_udp_addr,
     65       const SocketAddress& internal_tcp_addr,
     66       SocketFactory* external, const SocketAddress& external_ip);
     67   ~NATServer() override;
     68 
     69   SocketAddress internal_udp_address() const {
     70     return udp_server_socket_->GetLocalAddress();
     71   }
     72 
     73   SocketAddress internal_tcp_address() const {
     74     return tcp_proxy_server_->GetServerAddress();
     75   }
     76 
     77   // Packets received on one of the networks.
     78   void OnInternalUDPPacket(AsyncPacketSocket* socket, const char* buf,
     79                            size_t size, const SocketAddress& addr,
     80                            const PacketTime& packet_time);
     81   void OnExternalUDPPacket(AsyncPacketSocket* socket, const char* buf,
     82                            size_t size, const SocketAddress& remote_addr,
     83                            const PacketTime& packet_time);
     84 
     85  private:
     86   typedef std::set<SocketAddress, AddrCmp> AddressSet;
     87 
     88   /* Records a translation and the associated external socket. */
     89   struct TransEntry {
     90     TransEntry(const SocketAddressPair& r, AsyncUDPSocket* s, NAT* nat);
     91     ~TransEntry();
     92 
     93     void WhitelistInsert(const SocketAddress& addr);
     94     bool WhitelistContains(const SocketAddress& ext_addr);
     95 
     96     SocketAddressPair route;
     97     AsyncUDPSocket* socket;
     98     AddressSet* whitelist;
     99     CriticalSection crit_;
    100   };
    101 
    102   typedef std::map<SocketAddressPair, TransEntry*, RouteCmp> InternalMap;
    103   typedef std::map<SocketAddress, TransEntry*> ExternalMap;
    104 
    105   /* Creates a new entry that translates the given route. */
    106   void Translate(const SocketAddressPair& route);
    107 
    108   /* Determines whether the NAT would filter out a packet from this address. */
    109   bool ShouldFilterOut(TransEntry* entry, const SocketAddress& ext_addr);
    110 
    111   NAT* nat_;
    112   SocketFactory* external_;
    113   SocketAddress external_ip_;
    114   AsyncUDPSocket* udp_server_socket_;
    115   ProxyServer* tcp_proxy_server_;
    116   InternalMap* int_map_;
    117   ExternalMap* ext_map_;
    118   RTC_DISALLOW_COPY_AND_ASSIGN(NATServer);
    119 };
    120 
    121 }  // namespace rtc
    122 
    123 #endif  // WEBRTC_BASE_NATSERVER_H_
    124