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* Copyright 2004 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.
#if defined(WEBRTC_POSIX) && defined(WEBRTC_LINUX)
#include <sys/epoll.h>
#include <array>
#include <memory>
#include <unordered_map>
#include <vector>
#include "rtc_base/async_resolver.h"
#include "rtc_base/async_resolver_interface.h"
#include "rtc_base/deprecated/recursive_critical_section.h"
#include "rtc_base/socket_server.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/system/rtc_export.h"
#include "rtc_base/thread_annotations.h"
#if defined(WEBRTC_POSIX)
typedef int SOCKET;
#endif // WEBRTC_POSIX
namespace rtc {
// Event constants for the Dispatcher class.
enum DispatcherEvent {
DE_READ = 0x0001,
DE_WRITE = 0x0002,
DE_CONNECT = 0x0004,
DE_CLOSE = 0x0008,
DE_ACCEPT = 0x0010,
class Signaler;
class Dispatcher {
virtual ~Dispatcher() {}
virtual uint32_t GetRequestedEvents() = 0;
virtual void OnEvent(uint32_t ff, int err) = 0;
#if defined(WEBRTC_WIN)
virtual WSAEVENT GetWSAEvent() = 0;
virtual SOCKET GetSocket() = 0;
virtual bool CheckSignalClose() = 0;
#elif defined(WEBRTC_POSIX)
virtual int GetDescriptor() = 0;
virtual bool IsDescriptorClosed() = 0;
// A socket server that provides the real sockets of the underlying OS.
class RTC_EXPORT PhysicalSocketServer : public SocketServer {
~PhysicalSocketServer() override;
// SocketFactory:
Socket* CreateSocket(int family, int type) override;
// Internal Factory for Accept (virtual so it can be overwritten in tests).
virtual Socket* WrapSocket(SOCKET s);
// SocketServer:
bool Wait(int cms, bool process_io) override;
void WakeUp() override;
void Add(Dispatcher* dispatcher);
void Remove(Dispatcher* dispatcher);
void Update(Dispatcher* dispatcher);
// The number of events to process with one call to "epoll_wait".
static constexpr size_t kNumEpollEvents = 128;
#if defined(WEBRTC_POSIX)
bool WaitSelect(int cms, bool process_io);
#endif // WEBRTC_POSIX
#if defined(WEBRTC_USE_EPOLL)
void AddEpoll(Dispatcher* dispatcher, uint64_t key);
void RemoveEpoll(Dispatcher* dispatcher);
void UpdateEpoll(Dispatcher* dispatcher, uint64_t key);
bool WaitEpoll(int cms);
bool WaitPoll(int cms, Dispatcher* dispatcher);
// This array is accessed in isolation by a thread calling into Wait().
// It's useless to use a SequenceChecker to guard it because a socket
// server can outlive the thread it's bound to, forcing the Wait call
// to have to reset the sequence checker on Wait calls.
std::array<epoll_event, kNumEpollEvents> epoll_events_;
const int epoll_fd_ = INVALID_SOCKET;
// uint64_t keys are used to uniquely identify a dispatcher in order to avoid
// the ABA problem during the epoll loop (a dispatcher being destroyed and
// replaced by one with the same address).
uint64_t next_dispatcher_key_ RTC_GUARDED_BY(crit_) = 0;
std::unordered_map<uint64_t, Dispatcher*> dispatcher_by_key_
// Reverse lookup necessary for removals/updates.
std::unordered_map<Dispatcher*, uint64_t> key_by_dispatcher_
// A list of dispatcher keys that we're interested in for the current
// select() or WSAWaitForMultipleEvents() loop. Again, used to avoid the ABA
// problem (a socket being destroyed and a new one created with the same
// handle, erroneously receiving the events from the destroyed socket).
// Kept as a member variable just for efficiency.
std::vector<uint64_t> current_dispatcher_keys_;
Signaler* signal_wakeup_; // Assigned in constructor only
RecursiveCriticalSection crit_;
#if defined(WEBRTC_WIN)
const WSAEVENT socket_ev_;
bool fWait_;
// Are we currently in a select()/epoll()/WSAWaitForMultipleEvents loop?
// Used for a DCHECK, because we don't support reentrant waiting.
bool waiting_ = false;
class PhysicalSocket : public Socket, public sigslot::has_slots<> {
PhysicalSocket(PhysicalSocketServer* ss, SOCKET s = INVALID_SOCKET);
~PhysicalSocket() override;
// Creates the underlying OS socket (same as the "socket" function).
virtual bool Create(int family, int type);
SocketAddress GetLocalAddress() const override;
SocketAddress GetRemoteAddress() const override;
int Bind(const SocketAddress& bind_addr) override;
int Connect(const SocketAddress& addr) override;
int GetError() const override;
void SetError(int error) override;
ConnState GetState() const override;
int GetOption(Option opt, int* value) override;
int SetOption(Option opt, int value) override;
int Send(const void* pv, size_t cb) override;
int SendTo(const void* buffer,
size_t length,
const SocketAddress& addr) override;
int Recv(void* buffer, size_t length, int64_t* timestamp) override;
int RecvFrom(void* buffer,
size_t length,
SocketAddress* out_addr,
int64_t* timestamp) override;
int Listen(int backlog) override;
Socket* Accept(SocketAddress* out_addr) override;
int Close() override;
SocketServer* socketserver() { return ss_; }
int DoConnect(const SocketAddress& connect_addr);
// Make virtual so ::accept can be overwritten in tests.
virtual SOCKET DoAccept(SOCKET socket, sockaddr* addr, socklen_t* addrlen);
// Make virtual so ::send can be overwritten in tests.
virtual int DoSend(SOCKET socket, const char* buf, int len, int flags);
// Make virtual so ::sendto can be overwritten in tests.
virtual int DoSendTo(SOCKET socket,
const char* buf,
int len,
int flags,
const struct sockaddr* dest_addr,
socklen_t addrlen);
void OnResolveResult(AsyncResolverInterface* resolver);
void UpdateLastError();
void MaybeRemapSendError();
uint8_t enabled_events() const { return enabled_events_; }
virtual void SetEnabledEvents(uint8_t events);
virtual void EnableEvents(uint8_t events);
virtual void DisableEvents(uint8_t events);
int TranslateOption(Option opt, int* slevel, int* sopt);
PhysicalSocketServer* ss_;
bool udp_;
int family_ = 0;
mutable webrtc::Mutex mutex_;
int error_ RTC_GUARDED_BY(mutex_);
ConnState state_;
AsyncResolver* resolver_;
#if !defined(NDEBUG)
std::string dbg_addr_;
uint8_t enabled_events_ = 0;
class SocketDispatcher : public Dispatcher, public PhysicalSocket {
explicit SocketDispatcher(PhysicalSocketServer* ss);
SocketDispatcher(SOCKET s, PhysicalSocketServer* ss);
~SocketDispatcher() override;
bool Initialize();
virtual bool Create(int type);
bool Create(int family, int type) override;
#if defined(WEBRTC_WIN)
WSAEVENT GetWSAEvent() override;
SOCKET GetSocket() override;
bool CheckSignalClose() override;
#elif defined(WEBRTC_POSIX)
int GetDescriptor() override;
bool IsDescriptorClosed() override;
uint32_t GetRequestedEvents() override;
void OnEvent(uint32_t ff, int err) override;
int Close() override;
#if defined(WEBRTC_USE_EPOLL)
void StartBatchedEventUpdates();
void FinishBatchedEventUpdates();
void SetEnabledEvents(uint8_t events) override;
void EnableEvents(uint8_t events) override;
void DisableEvents(uint8_t events) override;
#if defined(WEBRTC_WIN)
static int next_id_;
int id_;
bool signal_close_;
int signal_err_;
#endif // WEBRTC_WIN
#if defined(WEBRTC_USE_EPOLL)
void MaybeUpdateDispatcher(uint8_t old_events);
int saved_enabled_events_ = -1;
} // namespace rtc