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
24namespace 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.
29struct 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.
39struct 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
57const int NAT_SERVER_UDP_PORT = 4237;
58const int NAT_SERVER_TCP_PORT = 4238;
59
60class 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