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 #include "webrtc/base/natsocketfactory.h"
12 #include "webrtc/base/natserver.h"
13 #include "webrtc/base/logging.h"
14
15 namespace rtc {
16
RouteCmp(NAT * nat)17 RouteCmp::RouteCmp(NAT* nat) : symmetric(nat->IsSymmetric()) {
18 }
19
operator ()(const SocketAddressPair & r) const20 size_t RouteCmp::operator()(const SocketAddressPair& r) const {
21 size_t h = r.source().Hash();
22 if (symmetric)
23 h ^= r.destination().Hash();
24 return h;
25 }
26
operator ()(const SocketAddressPair & r1,const SocketAddressPair & r2) const27 bool RouteCmp::operator()(
28 const SocketAddressPair& r1, const SocketAddressPair& r2) const {
29 if (r1.source() < r2.source())
30 return true;
31 if (r2.source() < r1.source())
32 return false;
33 if (symmetric && (r1.destination() < r2.destination()))
34 return true;
35 if (symmetric && (r2.destination() < r1.destination()))
36 return false;
37 return false;
38 }
39
AddrCmp(NAT * nat)40 AddrCmp::AddrCmp(NAT* nat)
41 : use_ip(nat->FiltersIP()), use_port(nat->FiltersPort()) {
42 }
43
operator ()(const SocketAddress & a) const44 size_t AddrCmp::operator()(const SocketAddress& a) const {
45 size_t h = 0;
46 if (use_ip)
47 h ^= HashIP(a.ipaddr());
48 if (use_port)
49 h ^= a.port() | (a.port() << 16);
50 return h;
51 }
52
operator ()(const SocketAddress & a1,const SocketAddress & a2) const53 bool AddrCmp::operator()(
54 const SocketAddress& a1, const SocketAddress& a2) const {
55 if (use_ip && (a1.ipaddr() < a2.ipaddr()))
56 return true;
57 if (use_ip && (a2.ipaddr() < a1.ipaddr()))
58 return false;
59 if (use_port && (a1.port() < a2.port()))
60 return true;
61 if (use_port && (a2.port() < a1.port()))
62 return false;
63 return false;
64 }
65
NATServer(NATType type,SocketFactory * internal,const SocketAddress & internal_addr,SocketFactory * external,const SocketAddress & external_ip)66 NATServer::NATServer(
67 NATType type, SocketFactory* internal, const SocketAddress& internal_addr,
68 SocketFactory* external, const SocketAddress& external_ip)
69 : external_(external), external_ip_(external_ip.ipaddr(), 0) {
70 nat_ = NAT::Create(type);
71
72 server_socket_ = AsyncUDPSocket::Create(internal, internal_addr);
73 server_socket_->SignalReadPacket.connect(this, &NATServer::OnInternalPacket);
74
75 int_map_ = new InternalMap(RouteCmp(nat_));
76 ext_map_ = new ExternalMap();
77 }
78
~NATServer()79 NATServer::~NATServer() {
80 for (InternalMap::iterator iter = int_map_->begin();
81 iter != int_map_->end();
82 iter++)
83 delete iter->second;
84
85 delete nat_;
86 delete server_socket_;
87 delete int_map_;
88 delete ext_map_;
89 }
90
OnInternalPacket(AsyncPacketSocket * socket,const char * buf,size_t size,const SocketAddress & addr,const PacketTime & packet_time)91 void NATServer::OnInternalPacket(
92 AsyncPacketSocket* socket, const char* buf, size_t size,
93 const SocketAddress& addr, const PacketTime& packet_time) {
94
95 // Read the intended destination from the wire.
96 SocketAddress dest_addr;
97 size_t length = UnpackAddressFromNAT(buf, size, &dest_addr);
98
99 // Find the translation for these addresses (allocating one if necessary).
100 SocketAddressPair route(addr, dest_addr);
101 InternalMap::iterator iter = int_map_->find(route);
102 if (iter == int_map_->end()) {
103 Translate(route);
104 iter = int_map_->find(route);
105 }
106 ASSERT(iter != int_map_->end());
107
108 // Allow the destination to send packets back to the source.
109 iter->second->WhitelistInsert(dest_addr);
110
111 // Send the packet to its intended destination.
112 rtc::PacketOptions options;
113 iter->second->socket->SendTo(buf + length, size - length, dest_addr, options);
114 }
115
OnExternalPacket(AsyncPacketSocket * socket,const char * buf,size_t size,const SocketAddress & remote_addr,const PacketTime & packet_time)116 void NATServer::OnExternalPacket(
117 AsyncPacketSocket* socket, const char* buf, size_t size,
118 const SocketAddress& remote_addr, const PacketTime& packet_time) {
119
120 SocketAddress local_addr = socket->GetLocalAddress();
121
122 // Find the translation for this addresses.
123 ExternalMap::iterator iter = ext_map_->find(local_addr);
124 ASSERT(iter != ext_map_->end());
125
126 // Allow the NAT to reject this packet.
127 if (ShouldFilterOut(iter->second, remote_addr)) {
128 LOG(LS_INFO) << "Packet from " << remote_addr.ToSensitiveString()
129 << " was filtered out by the NAT.";
130 return;
131 }
132
133 // Forward this packet to the internal address.
134 // First prepend the address in a quasi-STUN format.
135 scoped_ptr<char[]> real_buf(new char[size + kNATEncodedIPv6AddressSize]);
136 size_t addrlength = PackAddressForNAT(real_buf.get(),
137 size + kNATEncodedIPv6AddressSize,
138 remote_addr);
139 // Copy the data part after the address.
140 rtc::PacketOptions options;
141 memcpy(real_buf.get() + addrlength, buf, size);
142 server_socket_->SendTo(real_buf.get(), size + addrlength,
143 iter->second->route.source(), options);
144 }
145
Translate(const SocketAddressPair & route)146 void NATServer::Translate(const SocketAddressPair& route) {
147 AsyncUDPSocket* socket = AsyncUDPSocket::Create(external_, external_ip_);
148
149 if (!socket) {
150 LOG(LS_ERROR) << "Couldn't find a free port!";
151 return;
152 }
153
154 TransEntry* entry = new TransEntry(route, socket, nat_);
155 (*int_map_)[route] = entry;
156 (*ext_map_)[socket->GetLocalAddress()] = entry;
157 socket->SignalReadPacket.connect(this, &NATServer::OnExternalPacket);
158 }
159
ShouldFilterOut(TransEntry * entry,const SocketAddress & ext_addr)160 bool NATServer::ShouldFilterOut(TransEntry* entry,
161 const SocketAddress& ext_addr) {
162 return entry->WhitelistContains(ext_addr);
163 }
164
TransEntry(const SocketAddressPair & r,AsyncUDPSocket * s,NAT * nat)165 NATServer::TransEntry::TransEntry(
166 const SocketAddressPair& r, AsyncUDPSocket* s, NAT* nat)
167 : route(r), socket(s) {
168 whitelist = new AddressSet(AddrCmp(nat));
169 }
170
~TransEntry()171 NATServer::TransEntry::~TransEntry() {
172 delete whitelist;
173 delete socket;
174 }
175
WhitelistInsert(const SocketAddress & addr)176 void NATServer::TransEntry::WhitelistInsert(const SocketAddress& addr) {
177 CritScope cs(&crit_);
178 whitelist->insert(addr);
179 }
180
WhitelistContains(const SocketAddress & ext_addr)181 bool NATServer::TransEntry::WhitelistContains(const SocketAddress& ext_addr) {
182 CritScope cs(&crit_);
183 return whitelist->find(ext_addr) == whitelist->end();
184 }
185
186 } // namespace rtc
187