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 "p2p/base/stun_server.h"
12
13 #include <string>
14 #include <utility>
15
16 #include "absl/strings/string_view.h"
17 #include "rtc_base/byte_buffer.h"
18 #include "rtc_base/logging.h"
19
20 namespace cricket {
21
StunServer(rtc::AsyncUDPSocket * socket)22 StunServer::StunServer(rtc::AsyncUDPSocket* socket) : socket_(socket) {
23 socket_->SignalReadPacket.connect(this, &StunServer::OnPacket);
24 }
25
~StunServer()26 StunServer::~StunServer() {
27 socket_->SignalReadPacket.disconnect(this);
28 }
29
OnPacket(rtc::AsyncPacketSocket * socket,const char * buf,size_t size,const rtc::SocketAddress & remote_addr,const int64_t &)30 void StunServer::OnPacket(rtc::AsyncPacketSocket* socket,
31 const char* buf,
32 size_t size,
33 const rtc::SocketAddress& remote_addr,
34 const int64_t& /* packet_time_us */) {
35 // Parse the STUN message; eat any messages that fail to parse.
36 rtc::ByteBufferReader bbuf(buf, size);
37 StunMessage msg;
38 if (!msg.Read(&bbuf)) {
39 return;
40 }
41
42 // TODO(?): If unknown non-optional (<= 0x7fff) attributes are found, send a
43 // 420 "Unknown Attribute" response.
44
45 // Send the message to the appropriate handler function.
46 switch (msg.type()) {
47 case STUN_BINDING_REQUEST:
48 OnBindingRequest(&msg, remote_addr);
49 break;
50
51 default:
52 SendErrorResponse(msg, remote_addr, 600, "Operation Not Supported");
53 }
54 }
55
OnBindingRequest(StunMessage * msg,const rtc::SocketAddress & remote_addr)56 void StunServer::OnBindingRequest(StunMessage* msg,
57 const rtc::SocketAddress& remote_addr) {
58 StunMessage response(STUN_BINDING_RESPONSE, msg->transaction_id());
59 GetStunBindResponse(msg, remote_addr, &response);
60 SendResponse(response, remote_addr);
61 }
62
SendErrorResponse(const StunMessage & msg,const rtc::SocketAddress & addr,int error_code,absl::string_view error_desc)63 void StunServer::SendErrorResponse(const StunMessage& msg,
64 const rtc::SocketAddress& addr,
65 int error_code,
66 absl::string_view error_desc) {
67 StunMessage err_msg(GetStunErrorResponseType(msg.type()),
68 msg.transaction_id());
69
70 auto err_code = StunAttribute::CreateErrorCode();
71 err_code->SetCode(error_code);
72 err_code->SetReason(std::string(error_desc));
73 err_msg.AddAttribute(std::move(err_code));
74
75 SendResponse(err_msg, addr);
76 }
77
SendResponse(const StunMessage & msg,const rtc::SocketAddress & addr)78 void StunServer::SendResponse(const StunMessage& msg,
79 const rtc::SocketAddress& addr) {
80 rtc::ByteBufferWriter buf;
81 msg.Write(&buf);
82 rtc::PacketOptions options;
83 if (socket_->SendTo(buf.Data(), buf.Length(), addr, options) < 0)
84 RTC_LOG_ERR(LS_ERROR) << "sendto";
85 }
86
GetStunBindResponse(StunMessage * message,const rtc::SocketAddress & remote_addr,StunMessage * response) const87 void StunServer::GetStunBindResponse(StunMessage* message,
88 const rtc::SocketAddress& remote_addr,
89 StunMessage* response) const {
90 RTC_DCHECK_EQ(response->type(), STUN_BINDING_RESPONSE);
91 RTC_DCHECK_EQ(response->transaction_id(), message->transaction_id());
92
93 // Tell the user the address that we received their message from.
94 std::unique_ptr<StunAddressAttribute> mapped_addr;
95 if (message->IsLegacy()) {
96 mapped_addr = StunAttribute::CreateAddress(STUN_ATTR_MAPPED_ADDRESS);
97 } else {
98 mapped_addr = StunAttribute::CreateXorAddress(STUN_ATTR_XOR_MAPPED_ADDRESS);
99 }
100 mapped_addr->SetAddress(remote_addr);
101 response->AddAttribute(std::move(mapped_addr));
102 }
103
104 } // namespace cricket
105