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 RTC_BASE_NAT_SERVER_H_ 12 #define RTC_BASE_NAT_SERVER_H_ 13 14 #include <map> 15 #include <set> 16 17 #include "rtc_base/async_udp_socket.h" 18 #include "rtc_base/nat_types.h" 19 #include "rtc_base/proxy_server.h" 20 #include "rtc_base/socket_address_pair.h" 21 #include "rtc_base/socket_factory.h" 22 #include "rtc_base/synchronization/mutex.h" 23 #include "rtc_base/thread.h" 24 25 namespace rtc { 26 27 // Change how routes (socketaddress pairs) are compared based on the type of 28 // NAT. The NAT server maintains a hashtable of the routes that it knows 29 // about. So these affect which routes are treated the same. 30 struct RouteCmp { 31 explicit RouteCmp(NAT* nat); 32 size_t operator()(const SocketAddressPair& r) const; 33 bool operator()(const SocketAddressPair& r1, 34 const SocketAddressPair& r2) const; 35 36 bool symmetric; 37 }; 38 39 // Changes how addresses are compared based on the filtering rules of the NAT. 40 struct AddrCmp { 41 explicit AddrCmp(NAT* nat); 42 size_t operator()(const SocketAddress& r) const; 43 bool operator()(const SocketAddress& r1, const SocketAddress& r2) const; 44 45 bool use_ip; 46 bool use_port; 47 }; 48 49 // Implements the NAT device. It listens for packets on the internal network, 50 // translates them, and sends them out over the external network. 51 // 52 // TCP connections initiated from the internal side of the NAT server are 53 // also supported, by making a connection to the NAT server's TCP address and 54 // then sending the remote address in quasi-STUN format. The connection status 55 // will be indicated back to the client as a 1 byte status code, where '0' 56 // indicates success. 57 58 const int NAT_SERVER_UDP_PORT = 4237; 59 const int NAT_SERVER_TCP_PORT = 4238; 60 61 class NATServer : public sigslot::has_slots<> { 62 public: 63 NATServer(NATType type, 64 SocketFactory* internal, 65 const SocketAddress& internal_udp_addr, 66 const SocketAddress& internal_tcp_addr, 67 SocketFactory* external, 68 const SocketAddress& external_ip); 69 ~NATServer() override; 70 71 NATServer(const NATServer&) = delete; 72 NATServer& operator=(const NATServer&) = delete; 73 internal_udp_address()74 SocketAddress internal_udp_address() const { 75 return udp_server_socket_->GetLocalAddress(); 76 } 77 internal_tcp_address()78 SocketAddress internal_tcp_address() const { 79 return tcp_proxy_server_->GetServerAddress(); 80 } 81 82 // Packets received on one of the networks. 83 void OnInternalUDPPacket(AsyncPacketSocket* socket, 84 const char* buf, 85 size_t size, 86 const SocketAddress& addr, 87 const int64_t& packet_time_us); 88 void OnExternalUDPPacket(AsyncPacketSocket* socket, 89 const char* buf, 90 size_t size, 91 const SocketAddress& remote_addr, 92 const int64_t& packet_time_us); 93 94 private: 95 typedef std::set<SocketAddress, AddrCmp> AddressSet; 96 97 /* Records a translation and the associated external socket. */ 98 struct TransEntry { 99 TransEntry(const SocketAddressPair& r, AsyncUDPSocket* s, NAT* nat); 100 ~TransEntry(); 101 102 void AllowlistInsert(const SocketAddress& addr); 103 bool AllowlistContains(const SocketAddress& ext_addr); 104 105 SocketAddressPair route; 106 AsyncUDPSocket* socket; 107 AddressSet* allowlist; 108 webrtc::Mutex mutex_; 109 }; 110 111 typedef std::map<SocketAddressPair, TransEntry*, RouteCmp> InternalMap; 112 typedef std::map<SocketAddress, TransEntry*> ExternalMap; 113 114 /* Creates a new entry that translates the given route. */ 115 void Translate(const SocketAddressPair& route); 116 117 /* Determines whether the NAT would filter out a packet from this address. */ 118 bool ShouldFilterOut(TransEntry* entry, const SocketAddress& ext_addr); 119 120 NAT* nat_; 121 SocketFactory* external_; 122 SocketAddress external_ip_; 123 AsyncUDPSocket* udp_server_socket_; 124 ProxyServer* tcp_proxy_server_; 125 InternalMap* int_map_; 126 ExternalMap* ext_map_; 127 }; 128 129 } // namespace rtc 130 131 #endif // RTC_BASE_NAT_SERVER_H_ 132