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* Copyright 2012 The WebRTC Project Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
#include <list>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <utility>
#include <vector>
#include "absl/strings/string_view.h"
#include "api/sequence_checker.h"
#include "api/task_queue/pending_task_safety_flag.h"
#include "api/task_queue/task_queue_base.h"
#include "api/units/time_delta.h"
#include "p2p/base/port_interface.h"
#include "rtc_base/async_packet_socket.h"
#include "rtc_base/network/received_packet.h"
#include "rtc_base/socket_address.h"
#include "rtc_base/ssl_adapter.h"
#include "rtc_base/third_party/sigslot/sigslot.h"
namespace rtc {
class ByteBufferWriter;
class PacketSocketFactory;
} // namespace rtc
namespace cricket {
class StunMessage;
class TurnMessage;
class TurnServer;
// The default server port for TURN, as specified in RFC5766.
const int TURN_SERVER_PORT = 3478;
// Encapsulates the client's connection to the server.
class TurnServerConnection {
TurnServerConnection() : proto_(PROTO_UDP), socket_(NULL) {}
TurnServerConnection(const rtc::SocketAddress& src,
ProtocolType proto,
rtc::AsyncPacketSocket* socket);
const rtc::SocketAddress& src() const { return src_; }
rtc::AsyncPacketSocket* socket() { return socket_; }
bool operator==(const TurnServerConnection& t) const;
bool operator<(const TurnServerConnection& t) const;
std::string ToString() const;
rtc::SocketAddress src_;
rtc::SocketAddress dst_;
cricket::ProtocolType proto_;
rtc::AsyncPacketSocket* socket_;
// Encapsulates a TURN allocation.
// The object is created when an allocation request is received, and then
// handles TURN messages (via HandleTurnMessage) and channel data messages
// (via HandleChannelData) for this allocation when received by the server.
// The object informs the server when its lifetime timer expires.
class TurnServerAllocation {
TurnServerAllocation(TurnServer* server_,
webrtc::TaskQueueBase* thread,
const TurnServerConnection& conn,
rtc::AsyncPacketSocket* server_socket,
absl::string_view key);
virtual ~TurnServerAllocation();
TurnServerConnection* conn() { return &conn_; }
const std::string& key() const { return key_; }
const std::string& transaction_id() const { return transaction_id_; }
const std::string& username() const { return username_; }
const std::string& last_nonce() const { return last_nonce_; }
void set_last_nonce(absl::string_view nonce) {
last_nonce_ = std::string(nonce);
std::string ToString() const;
void HandleTurnMessage(const TurnMessage* msg);
void HandleChannelData(rtc::ArrayView<const uint8_t> payload);
struct Channel {
webrtc::ScopedTaskSafety pending_delete;
int id;
rtc::SocketAddress peer;
struct Permission {
webrtc::ScopedTaskSafety pending_delete;
rtc::IPAddress peer;
using PermissionList = std::list<Permission>;
using ChannelList = std::list<Channel>;
void PostDeleteSelf(webrtc::TimeDelta delay);
void HandleAllocateRequest(const TurnMessage* msg);
void HandleRefreshRequest(const TurnMessage* msg);
void HandleSendIndication(const TurnMessage* msg);
void HandleCreatePermissionRequest(const TurnMessage* msg);
void HandleChannelBindRequest(const TurnMessage* msg);
void OnExternalPacket(rtc::AsyncPacketSocket* socket,
const rtc::ReceivedPacket& packet);
static webrtc::TimeDelta ComputeLifetime(const TurnMessage& msg);
bool HasPermission(const rtc::IPAddress& addr);
void AddPermission(const rtc::IPAddress& addr);
PermissionList::iterator FindPermission(const rtc::IPAddress& addr);
ChannelList::iterator FindChannel(int channel_id);
ChannelList::iterator FindChannel(const rtc::SocketAddress& addr);
void SendResponse(TurnMessage* msg);
void SendBadRequestResponse(const TurnMessage* req);
void SendErrorResponse(const TurnMessage* req,
int code,
absl::string_view reason);
void SendExternal(const void* data,
size_t size,
const rtc::SocketAddress& peer);
TurnServer* const server_;
webrtc::TaskQueueBase* const thread_;
TurnServerConnection conn_;
std::unique_ptr<rtc::AsyncPacketSocket> external_socket_;
std::string key_;
std::string transaction_id_;
std::string username_;
std::string last_nonce_;
PermissionList perms_;
ChannelList channels_;
webrtc::ScopedTaskSafety safety_;
// An interface through which the MD5 credential hash can be retrieved.
class TurnAuthInterface {
// Gets HA1 for the specified user and realm.
// HA1 = MD5(A1) = MD5(username:realm:password).
// Return true if the given username and realm are valid, or false if not.
virtual bool GetKey(absl::string_view username,
absl::string_view realm,
std::string* key) = 0;
virtual ~TurnAuthInterface() = default;
// An interface enables Turn Server to control redirection behavior.
class TurnRedirectInterface {
virtual bool ShouldRedirect(const rtc::SocketAddress& address,
rtc::SocketAddress* out) = 0;
virtual ~TurnRedirectInterface() {}
class StunMessageObserver {
virtual void ReceivedMessage(const TurnMessage* msg) = 0;
virtual void ReceivedChannelData(rtc::ArrayView<const uint8_t> payload) = 0;
virtual ~StunMessageObserver() {}
// The core TURN server class. Give it a socket to listen on via
// AddInternalServerSocket, and a factory to create external sockets via
// SetExternalSocketFactory, and it's ready to go.
// Not yet wired up: TCP support.
class TurnServer : public sigslot::has_slots<> {
typedef std::map<TurnServerConnection, std::unique_ptr<TurnServerAllocation>>
explicit TurnServer(webrtc::TaskQueueBase* thread);
~TurnServer() override;
// Gets/sets the realm value to use for the server.
const std::string& realm() const {
return realm_;
void set_realm(absl::string_view realm) {
realm_ = std::string(realm);
// Gets/sets the value for the SOFTWARE attribute for TURN messages.
const std::string& software() const {
return software_;
void set_software(absl::string_view software) {
software_ = std::string(software);
const AllocationMap& allocations() const {
return allocations_;
// Sets the authentication callback; does not take ownership.
void set_auth_hook(TurnAuthInterface* auth_hook) {
auth_hook_ = auth_hook;
void set_redirect_hook(TurnRedirectInterface* redirect_hook) {
redirect_hook_ = redirect_hook;
void set_enable_otu_nonce(bool enable) {
enable_otu_nonce_ = enable;
// If set to true, reject CreatePermission requests to RFC1918 addresses.
void set_reject_private_addresses(bool filter) {
reject_private_addresses_ = filter;
void set_enable_permission_checks(bool enable) {
enable_permission_checks_ = enable;
// Starts listening for packets from internal clients.
void AddInternalSocket(rtc::AsyncPacketSocket* socket, ProtocolType proto);
// Starts listening for the connections on this socket. When someone tries
// to connect, the connection will be accepted and a new internal socket
// will be added.
void AddInternalServerSocket(
rtc::Socket* socket,
ProtocolType proto,
std::unique_ptr<rtc::SSLAdapterFactory> ssl_adapter_factory = nullptr);
// Specifies the factory to use for creating external sockets.
void SetExternalSocketFactory(rtc::PacketSocketFactory* factory,
const rtc::SocketAddress& address);
// For testing only.
std::string SetTimestampForNextNonce(int64_t timestamp) {
ts_for_next_nonce_ = timestamp;
return GenerateNonce(timestamp);
void SetStunMessageObserver(std::unique_ptr<StunMessageObserver> observer) {
stun_message_observer_ = std::move(observer);
// All private member functions and variables should have access restricted to
// thread_. But compile-time annotations are missing for members access from
// TurnServerAllocation (via friend declaration).
std::string GenerateNonce(int64_t now) const RTC_RUN_ON(thread_);
void OnInternalPacket(rtc::AsyncPacketSocket* socket,
const rtc::ReceivedPacket& packet) RTC_RUN_ON(thread_);
void OnNewInternalConnection(rtc::Socket* socket);
// Accept connections on this server socket.
void AcceptConnection(rtc::Socket* server_socket) RTC_RUN_ON(thread_);
void OnInternalSocketClose(rtc::AsyncPacketSocket* socket, int err);
void HandleStunMessage(TurnServerConnection* conn,
rtc::ArrayView<const uint8_t> payload)
void HandleBindingRequest(TurnServerConnection* conn, const StunMessage* msg)
void HandleAllocateRequest(TurnServerConnection* conn,
const TurnMessage* msg,
absl::string_view key) RTC_RUN_ON(thread_);
bool GetKey(const StunMessage* msg, std::string* key) RTC_RUN_ON(thread_);
bool CheckAuthorization(TurnServerConnection* conn,
StunMessage* msg,
absl::string_view key) RTC_RUN_ON(thread_);
bool ValidateNonce(absl::string_view nonce) const RTC_RUN_ON(thread_);
TurnServerAllocation* FindAllocation(TurnServerConnection* conn)
TurnServerAllocation* CreateAllocation(TurnServerConnection* conn,
int proto,
absl::string_view key)
void SendErrorResponse(TurnServerConnection* conn,
const StunMessage* req,
int code,
absl::string_view reason);
void SendErrorResponseWithRealmAndNonce(TurnServerConnection* conn,
const StunMessage* req,
int code,
absl::string_view reason)
void SendErrorResponseWithAlternateServer(TurnServerConnection* conn,
const StunMessage* req,
const rtc::SocketAddress& addr)
void SendStun(TurnServerConnection* conn, StunMessage* msg);
void Send(TurnServerConnection* conn, const rtc::ByteBufferWriter& buf);
void DestroyAllocation(TurnServerAllocation* allocation) RTC_RUN_ON(thread_);
void DestroyInternalSocket(rtc::AsyncPacketSocket* socket)
typedef std::map<rtc::AsyncPacketSocket*, ProtocolType> InternalSocketMap;
struct ServerSocketInfo {
ProtocolType proto;
// If non-null, used to wrap accepted sockets.
std::unique_ptr<rtc::SSLAdapterFactory> ssl_adapter_factory;
typedef std::map<rtc::Socket*, ServerSocketInfo> ServerSocketMap;
webrtc::TaskQueueBase* const thread_;
const std::string nonce_key_;
std::string realm_ RTC_GUARDED_BY(thread_);
std::string software_ RTC_GUARDED_BY(thread_);
TurnAuthInterface* auth_hook_ RTC_GUARDED_BY(thread_);
TurnRedirectInterface* redirect_hook_ RTC_GUARDED_BY(thread_);
// otu - one-time-use. Server will respond with 438 if it's
// sees the same nonce in next transaction.
bool enable_otu_nonce_ RTC_GUARDED_BY(thread_);
bool reject_private_addresses_ = false;
// Check for permission when receiving an external packet.
bool enable_permission_checks_ = true;
InternalSocketMap server_sockets_ RTC_GUARDED_BY(thread_);
ServerSocketMap server_listen_sockets_ RTC_GUARDED_BY(thread_);
std::unique_ptr<rtc::PacketSocketFactory> external_socket_factory_
rtc::SocketAddress external_addr_ RTC_GUARDED_BY(thread_);
AllocationMap allocations_ RTC_GUARDED_BY(thread_);
// For testing only. If this is non-zero, the next NONCE will be generated
// from this value, and it will be reset to 0 after generating the NONCE.
int64_t ts_for_next_nonce_ RTC_GUARDED_BY(thread_) = 0;
// For testing only. Used to observe STUN messages received.
std::unique_ptr<StunMessageObserver> stun_message_observer_
friend class TurnServerAllocation;
} // namespace cricket