Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1953 insertions, 0 deletions

diff --git a/third_party/libwebrtc/rtc_base/physical_socket_server.cc b/third_party/libwebrtc/rtc_base/physical_socket_server.cc
new file mode 100644
index 0000000000..95ba130e91
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/physical_socket_server.cc
@@ -0,0 +1,1953 @@
+/*
+ *  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.
+ */
+#include "rtc_base/physical_socket_server.h"
+
+#include <cstdint>
+#include <utility>
+
+#if defined(_MSC_VER) && _MSC_VER < 1300
+#pragma warning(disable : 4786)
+#endif
+
+#ifdef MEMORY_SANITIZER
+#include <sanitizer/msan_interface.h>
+#endif
+
+#if defined(WEBRTC_POSIX)
+#include <fcntl.h>
+#if defined(WEBRTC_USE_EPOLL)
+// "poll" will be used to wait for the signal dispatcher.
+#include <poll.h>
+#elif defined(WEBRTC_USE_POLL)
+#include <poll.h>
+#endif
+#include <sys/ioctl.h>
+#include <sys/select.h>
+#include <unistd.h>
+#endif
+
+#if defined(WEBRTC_WIN)
+#include <windows.h>
+#include <winsock2.h>
+#include <ws2tcpip.h>
+
+#undef SetPort
+#endif
+
+#include <errno.h>
+
+#include "rtc_base/async_dns_resolver.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/event.h"
+#include "rtc_base/ip_address.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/network_monitor.h"
+#include "rtc_base/synchronization/mutex.h"
+#include "rtc_base/time_utils.h"
+#include "system_wrappers/include/field_trial.h"
+
+#if defined(WEBRTC_LINUX)
+#include <linux/sockios.h>
+#endif
+
+#if defined(WEBRTC_WIN)
+#define LAST_SYSTEM_ERROR (::GetLastError())
+#elif defined(__native_client__) && __native_client__
+#define LAST_SYSTEM_ERROR (0)
+#elif defined(WEBRTC_POSIX)
+#define LAST_SYSTEM_ERROR (errno)
+#endif  // WEBRTC_WIN
+
+#if defined(WEBRTC_POSIX)
+#include <netinet/tcp.h>  // for TCP_NODELAY
+
+#define IP_MTU 14  // Until this is integrated from linux/in.h to netinet/in.h
+typedef void* SockOptArg;
+
+#endif  // WEBRTC_POSIX
+
+#if defined(WEBRTC_POSIX) && !defined(WEBRTC_MAC) && !defined(WEBRTC_BSD) && !defined(__native_client__)
+#if defined(WEBRTC_LINUX)
+#include <linux/sockios.h>
+#endif
+
+int64_t GetSocketRecvTimestamp(int socket) {
+  struct timeval tv_ioctl;
+  int ret = ioctl(socket, SIOCGSTAMP, &tv_ioctl);
+  if (ret != 0)
+    return -1;
+  int64_t timestamp =
+      rtc::kNumMicrosecsPerSec * static_cast<int64_t>(tv_ioctl.tv_sec) +
+      static_cast<int64_t>(tv_ioctl.tv_usec);
+  return timestamp;
+}
+
+#else
+
+int64_t GetSocketRecvTimestamp(int socket) {
+  return -1;
+}
+#endif
+
+#if defined(WEBRTC_WIN)
+typedef char* SockOptArg;
+#endif
+
+#if defined(WEBRTC_USE_EPOLL)
+// POLLRDHUP / EPOLLRDHUP are only defined starting with Linux 2.6.17.
+#if !defined(POLLRDHUP)
+#define POLLRDHUP 0x2000
+#endif
+#if !defined(EPOLLRDHUP)
+#define EPOLLRDHUP 0x2000
+#endif
+#endif
+
+namespace {
+class ScopedSetTrue {
+ public:
+  ScopedSetTrue(bool* value) : value_(value) {
+    RTC_DCHECK(!*value_);
+    *value_ = true;
+  }
+  ~ScopedSetTrue() { *value_ = false; }
+
+ private:
+  bool* value_;
+};
+
+// Returns true if the experiement "WebRTC-SCM-Timestamp" is explicitly
+// disabled.
+bool IsScmTimeStampExperimentDisabled() {
+  return webrtc::field_trial::IsDisabled("WebRTC-SCM-Timestamp");
+}
+}  // namespace
+
+namespace rtc {
+
+PhysicalSocket::PhysicalSocket(PhysicalSocketServer* ss, SOCKET s)
+    : ss_(ss),
+      s_(s),
+      error_(0),
+      state_((s == INVALID_SOCKET) ? CS_CLOSED : CS_CONNECTED),
+      resolver_(nullptr),
+      read_scm_timestamp_experiment_(!IsScmTimeStampExperimentDisabled()) {
+  if (s_ != INVALID_SOCKET) {
+    SetEnabledEvents(DE_READ | DE_WRITE);
+
+    int type = SOCK_STREAM;
+    socklen_t len = sizeof(type);
+    const int res =
+        getsockopt(s_, SOL_SOCKET, SO_TYPE, (SockOptArg)&type, &len);
+    RTC_DCHECK_EQ(0, res);
+    udp_ = (SOCK_DGRAM == type);
+  }
+}
+
+PhysicalSocket::~PhysicalSocket() {
+  Close();
+}
+
+bool PhysicalSocket::Create(int family, int type) {
+  Close();
+  s_ = ::socket(family, type, 0);
+  udp_ = (SOCK_DGRAM == type);
+  family_ = family;
+  UpdateLastError();
+  if (udp_) {
+    SetEnabledEvents(DE_READ | DE_WRITE);
+  }
+  return s_ != INVALID_SOCKET;
+}
+
+SocketAddress PhysicalSocket::GetLocalAddress() const {
+  sockaddr_storage addr_storage = {};
+  socklen_t addrlen = sizeof(addr_storage);
+  sockaddr* addr = reinterpret_cast<sockaddr*>(&addr_storage);
+  int result = ::getsockname(s_, addr, &addrlen);
+  SocketAddress address;
+  if (result >= 0) {
+    SocketAddressFromSockAddrStorage(addr_storage, &address);
+  } else {
+    RTC_LOG(LS_WARNING) << "GetLocalAddress: unable to get local addr, socket="
+                        << s_;
+  }
+  return address;
+}
+
+SocketAddress PhysicalSocket::GetRemoteAddress() const {
+  sockaddr_storage addr_storage = {};
+  socklen_t addrlen = sizeof(addr_storage);
+  sockaddr* addr = reinterpret_cast<sockaddr*>(&addr_storage);
+  int result = ::getpeername(s_, addr, &addrlen);
+  SocketAddress address;
+  if (result >= 0) {
+    SocketAddressFromSockAddrStorage(addr_storage, &address);
+  } else {
+    RTC_LOG(LS_WARNING)
+        << "GetRemoteAddress: unable to get remote addr, socket=" << s_;
+  }
+  return address;
+}
+
+int PhysicalSocket::Bind(const SocketAddress& bind_addr) {
+  SocketAddress copied_bind_addr = bind_addr;
+  // If a network binder is available, use it to bind a socket to an interface
+  // instead of bind(), since this is more reliable on an OS with a weak host
+  // model.
+  if (ss_->network_binder() && !bind_addr.IsAnyIP()) {
+    NetworkBindingResult result =
+        ss_->network_binder()->BindSocketToNetwork(s_, bind_addr.ipaddr());
+    if (result == NetworkBindingResult::SUCCESS) {
+      // Since the network binder handled binding the socket to the desired
+      // network interface, we don't need to (and shouldn't) include an IP in
+      // the bind() call; bind() just needs to assign a port.
+      copied_bind_addr.SetIP(GetAnyIP(copied_bind_addr.ipaddr().family()));
+    } else if (result == NetworkBindingResult::NOT_IMPLEMENTED) {
+      RTC_LOG(LS_INFO) << "Can't bind socket to network because "
+                          "network binding is not implemented for this OS.";
+    } else {
+      if (bind_addr.IsLoopbackIP()) {
+        // If we couldn't bind to a loopback IP (which should only happen in
+        // test scenarios), continue on. This may be expected behavior.
+        RTC_LOG(LS_VERBOSE) << "Binding socket to loopback address"
+                            << " failed; result: " << static_cast<int>(result);
+      } else {
+        RTC_LOG(LS_WARNING) << "Binding socket to network address"
+                            << " failed; result: " << static_cast<int>(result);
+        // If a network binding was attempted and failed, we should stop here
+        // and not try to use the socket. Otherwise, we may end up sending
+        // packets with an invalid source address.
+        // See: https://bugs.chromium.org/p/webrtc/issues/detail?id=7026
+        return -1;
+      }
+    }
+  }
+  sockaddr_storage addr_storage;
+  size_t len = copied_bind_addr.ToSockAddrStorage(&addr_storage);
+  sockaddr* addr = reinterpret_cast<sockaddr*>(&addr_storage);
+  int err = ::bind(s_, addr, static_cast<int>(len));
+  UpdateLastError();
+#if !defined(NDEBUG)
+  if (0 == err) {
+    dbg_addr_ = "Bound @ ";
+    dbg_addr_.append(GetLocalAddress().ToString());
+  }
+#endif
+  return err;
+}
+
+int PhysicalSocket::Connect(const SocketAddress& addr) {
+  // TODO(pthatcher): Implicit creation is required to reconnect...
+  // ...but should we make it more explicit?
+  if (state_ != CS_CLOSED) {
+    SetError(EALREADY);
+    return SOCKET_ERROR;
+  }
+  if (addr.IsUnresolvedIP()) {
+    RTC_LOG(LS_VERBOSE) << "Resolving addr in PhysicalSocket::Connect";
+    resolver_ = std::make_unique<webrtc::AsyncDnsResolver>();
+    resolver_->Start(addr, [this] { OnResolveResult(resolver_->result()); });
+    state_ = CS_CONNECTING;
+    return 0;
+  }
+
+  return DoConnect(addr);
+}
+
+int PhysicalSocket::DoConnect(const SocketAddress& connect_addr) {
+  if ((s_ == INVALID_SOCKET) && !Create(connect_addr.family(), SOCK_STREAM)) {
+    return SOCKET_ERROR;
+  }
+  sockaddr_storage addr_storage;
+  size_t len = connect_addr.ToSockAddrStorage(&addr_storage);
+  sockaddr* addr = reinterpret_cast<sockaddr*>(&addr_storage);
+  int err = ::connect(s_, addr, static_cast<int>(len));
+  UpdateLastError();
+  uint8_t events = DE_READ | DE_WRITE;
+  if (err == 0) {
+    state_ = CS_CONNECTED;
+  } else if (IsBlockingError(GetError())) {
+    state_ = CS_CONNECTING;
+    events |= DE_CONNECT;
+  } else {
+    return SOCKET_ERROR;
+  }
+
+  EnableEvents(events);
+  return 0;
+}
+
+int PhysicalSocket::GetError() const {
+  webrtc::MutexLock lock(&mutex_);
+  return error_;
+}
+
+void PhysicalSocket::SetError(int error) {
+  webrtc::MutexLock lock(&mutex_);
+  error_ = error;
+}
+
+Socket::ConnState PhysicalSocket::GetState() const {
+  return state_;
+}
+
+int PhysicalSocket::GetOption(Option opt, int* value) {
+  int slevel;
+  int sopt;
+  if (TranslateOption(opt, &slevel, &sopt) == -1)
+    return -1;
+  socklen_t optlen = sizeof(*value);
+  int ret = ::getsockopt(s_, slevel, sopt, (SockOptArg)value, &optlen);
+  if (ret == -1) {
+    return -1;
+  }
+  if (opt == OPT_DONTFRAGMENT) {
+#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
+    *value = (*value != IP_PMTUDISC_DONT) ? 1 : 0;
+#endif
+  } else if (opt == OPT_DSCP) {
+#if defined(WEBRTC_POSIX)
+    // unshift DSCP value to get six most significant bits of IP DiffServ field
+    *value >>= 2;
+#endif
+  }
+  return ret;
+}
+
+int PhysicalSocket::SetOption(Option opt, int value) {
+  int slevel;
+  int sopt;
+  if (TranslateOption(opt, &slevel, &sopt) == -1)
+    return -1;
+  if (opt == OPT_DONTFRAGMENT) {
+#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
+    value = (value) ? IP_PMTUDISC_DO : IP_PMTUDISC_DONT;
+#endif
+  } else if (opt == OPT_DSCP) {
+#if defined(WEBRTC_POSIX)
+    // shift DSCP value to fit six most significant bits of IP DiffServ field
+    value <<= 2;
+#endif
+  }
+#if defined(WEBRTC_POSIX)
+  if (sopt == IPV6_TCLASS) {
+    // Set the IPv4 option in all cases to support dual-stack sockets.
+    // Don't bother checking the return code, as this is expected to fail if
+    // it's not actually dual-stack.
+    ::setsockopt(s_, IPPROTO_IP, IP_TOS, (SockOptArg)&value, sizeof(value));
+  }
+#endif
+  int result =
+      ::setsockopt(s_, slevel, sopt, (SockOptArg)&value, sizeof(value));
+  if (result != 0) {
+    UpdateLastError();
+  }
+  return result;
+}
+
+int PhysicalSocket::Send(const void* pv, size_t cb) {
+  int sent = DoSend(
+      s_, reinterpret_cast<const char*>(pv), static_cast<int>(cb),
+#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
+      // Suppress SIGPIPE. Without this, attempting to send on a socket whose
+      // other end is closed will result in a SIGPIPE signal being raised to
+      // our process, which by default will terminate the process, which we
+      // don't want. By specifying this flag, we'll just get the error EPIPE
+      // instead and can handle the error gracefully.
+      MSG_NOSIGNAL
+#else
+      0
+#endif
+  );
+  UpdateLastError();
+  MaybeRemapSendError();
+  // We have seen minidumps where this may be false.
+  RTC_DCHECK(sent <= static_cast<int>(cb));
+  if ((sent > 0 && sent < static_cast<int>(cb)) ||
+      (sent < 0 && IsBlockingError(GetError()))) {
+    EnableEvents(DE_WRITE);
+  }
+  return sent;
+}
+
+int PhysicalSocket::SendTo(const void* buffer,
+                           size_t length,
+                           const SocketAddress& addr) {
+  sockaddr_storage saddr;
+  size_t len = addr.ToSockAddrStorage(&saddr);
+  int sent =
+      DoSendTo(s_, static_cast<const char*>(buffer), static_cast<int>(length),
+#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
+               // Suppress SIGPIPE. See above for explanation.
+               MSG_NOSIGNAL,
+#else
+               0,
+#endif
+               reinterpret_cast<sockaddr*>(&saddr), static_cast<int>(len));
+  UpdateLastError();
+  MaybeRemapSendError();
+  // We have seen minidumps where this may be false.
+  RTC_DCHECK(sent <= static_cast<int>(length));
+  if ((sent > 0 && sent < static_cast<int>(length)) ||
+      (sent < 0 && IsBlockingError(GetError()))) {
+    EnableEvents(DE_WRITE);
+  }
+  return sent;
+}
+
+int PhysicalSocket::Recv(void* buffer, size_t length, int64_t* timestamp) {
+  int received =
+      DoReadFromSocket(buffer, length, /*out_addr*/ nullptr, timestamp);
+  if ((received == 0) && (length != 0)) {
+    // Note: on graceful shutdown, recv can return 0.  In this case, we
+    // pretend it is blocking, and then signal close, so that simplifying
+    // assumptions can be made about Recv.
+    RTC_LOG(LS_WARNING) << "EOF from socket; deferring close event";
+    // Must turn this back on so that the select() loop will notice the close
+    // event.
+    EnableEvents(DE_READ);
+    SetError(EWOULDBLOCK);
+    return SOCKET_ERROR;
+  }
+
+  UpdateLastError();
+  int error = GetError();
+  bool success = (received >= 0) || IsBlockingError(error);
+  if (udp_ || success) {
+    EnableEvents(DE_READ);
+  }
+  if (!success) {
+    RTC_LOG_F(LS_VERBOSE) << "Error = " << error;
+  }
+  return received;
+}
+
+int PhysicalSocket::RecvFrom(void* buffer,
+                             size_t length,
+                             SocketAddress* out_addr,
+                             int64_t* timestamp) {
+  int received = DoReadFromSocket(buffer, length, out_addr, timestamp);
+  UpdateLastError();
+  int error = GetError();
+  bool success = (received >= 0) || IsBlockingError(error);
+  if (udp_ || success) {
+    EnableEvents(DE_READ);
+  }
+  if (!success) {
+    RTC_LOG_F(LS_VERBOSE) << "Error = " << error;
+  }
+  return received;
+}
+
+int PhysicalSocket::DoReadFromSocket(void* buffer,
+                                     size_t length,
+                                     SocketAddress* out_addr,
+                                     int64_t* timestamp) {
+  sockaddr_storage addr_storage;
+  socklen_t addr_len = sizeof(addr_storage);
+  sockaddr* addr = reinterpret_cast<sockaddr*>(&addr_storage);
+
+#if defined(WEBRTC_POSIX)
+  int received = 0;
+  if (read_scm_timestamp_experiment_) {
+    iovec iov = {.iov_base = buffer, .iov_len = length};
+    msghdr msg = {.msg_name = nullptr, .msg_namelen = 0, .msg_iov = &iov, .msg_iovlen = 1};
+    if (out_addr) {
+      out_addr->Clear();
+      msg.msg_name = addr;
+      msg.msg_namelen = addr_len;
+    }
+    char control[CMSG_SPACE(sizeof(struct timeval))] = {};
+    if (timestamp) {
+      *timestamp = -1;
+      msg.msg_control = &control;
+      msg.msg_controllen = sizeof(control);
+    }
+    received = ::recvmsg(s_, &msg, 0);
+    if (received <= 0) {
+      // An error occured or shut down.
+      return received;
+    }
+    if (timestamp) {
+      struct cmsghdr* cmsg;
+      for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+        if (cmsg->cmsg_level != SOL_SOCKET)
+          continue;
+        if (cmsg->cmsg_type == SCM_TIMESTAMP) {
+          timeval* ts = reinterpret_cast<timeval*>(CMSG_DATA(cmsg));
+          *timestamp =
+              rtc::kNumMicrosecsPerSec * static_cast<int64_t>(ts->tv_sec) +
+              static_cast<int64_t>(ts->tv_usec);
+          break;
+        }
+      }
+    }
+    if (out_addr) {
+      SocketAddressFromSockAddrStorage(addr_storage, out_addr);
+    }
+  } else {  // !read_scm_timestamp_experiment_
+    if (out_addr) {
+      received = ::recvfrom(s_, static_cast<char*>(buffer),
+                            static_cast<int>(length), 0, addr, &addr_len);
+      SocketAddressFromSockAddrStorage(addr_storage, out_addr);
+    } else {
+      received =
+          ::recv(s_, static_cast<char*>(buffer), static_cast<int>(length), 0);
+    }
+    if (timestamp) {
+      *timestamp = GetSocketRecvTimestamp(s_);
+    }
+  }
+  return received;
+
+#else
+  int received = 0;
+  if (out_addr) {
+    received = ::recvfrom(s_, static_cast<char*>(buffer),
+                          static_cast<int>(length), 0, addr, &addr_len);
+    SocketAddressFromSockAddrStorage(addr_storage, out_addr);
+  } else {
+    received =
+        ::recv(s_, static_cast<char*>(buffer), static_cast<int>(length), 0);
+  }
+  if (timestamp) {
+    *timestamp = -1;
+  }
+  return received;
+#endif
+}
+
+int PhysicalSocket::Listen(int backlog) {
+  int err = ::listen(s_, backlog);
+  UpdateLastError();
+  if (err == 0) {
+    state_ = CS_CONNECTING;
+    EnableEvents(DE_ACCEPT);
+#if !defined(NDEBUG)
+    dbg_addr_ = "Listening @ ";
+    dbg_addr_.append(GetLocalAddress().ToString());
+#endif
+  }
+  return err;
+}
+
+Socket* PhysicalSocket::Accept(SocketAddress* out_addr) {
+  // Always re-subscribe DE_ACCEPT to make sure new incoming connections will
+  // trigger an event even if DoAccept returns an error here.
+  EnableEvents(DE_ACCEPT);
+  sockaddr_storage addr_storage;
+  socklen_t addr_len = sizeof(addr_storage);
+  sockaddr* addr = reinterpret_cast<sockaddr*>(&addr_storage);
+  SOCKET s = DoAccept(s_, addr, &addr_len);
+  UpdateLastError();
+  if (s == INVALID_SOCKET)
+    return nullptr;
+  if (out_addr != nullptr)
+    SocketAddressFromSockAddrStorage(addr_storage, out_addr);
+  return ss_->WrapSocket(s);
+}
+
+int PhysicalSocket::Close() {
+  if (s_ == INVALID_SOCKET)
+    return 0;
+  int err = ::closesocket(s_);
+  UpdateLastError();
+  s_ = INVALID_SOCKET;
+  state_ = CS_CLOSED;
+  SetEnabledEvents(0);
+  if (resolver_) {
+    resolver_.reset();
+  }
+  return err;
+}
+
+SOCKET PhysicalSocket::DoAccept(SOCKET socket,
+                                sockaddr* addr,
+                                socklen_t* addrlen) {
+  return ::accept(socket, addr, addrlen);
+}
+
+int PhysicalSocket::DoSend(SOCKET socket, const char* buf, int len, int flags) {
+  return ::send(socket, buf, len, flags);
+}
+
+int PhysicalSocket::DoSendTo(SOCKET socket,
+                             const char* buf,
+                             int len,
+                             int flags,
+                             const struct sockaddr* dest_addr,
+                             socklen_t addrlen) {
+  return ::sendto(socket, buf, len, flags, dest_addr, addrlen);
+}
+
+void PhysicalSocket::OnResolveResult(
+    const webrtc::AsyncDnsResolverResult& result) {
+  int error = result.GetError();
+  if (error == 0) {
+    SocketAddress address;
+    if (result.GetResolvedAddress(AF_INET, &address)) {
+      error = DoConnect(address);
+    } else {
+      Close();
+    }
+  } else {
+    Close();
+  }
+
+  if (error) {
+    SetError(error);
+    SignalCloseEvent(this, error);
+  }
+}
+
+void PhysicalSocket::UpdateLastError() {
+  SetError(LAST_SYSTEM_ERROR);
+}
+
+void PhysicalSocket::MaybeRemapSendError() {
+#if defined(WEBRTC_MAC)
+  // https://developer.apple.com/library/mac/documentation/Darwin/
+  // Reference/ManPages/man2/sendto.2.html
+  // ENOBUFS - The output queue for a network interface is full.
+  // This generally indicates that the interface has stopped sending,
+  // but may be caused by transient congestion.
+  if (GetError() == ENOBUFS) {
+    SetError(EWOULDBLOCK);
+  }
+#endif
+}
+
+void PhysicalSocket::SetEnabledEvents(uint8_t events) {
+  enabled_events_ = events;
+}
+
+void PhysicalSocket::EnableEvents(uint8_t events) {
+  enabled_events_ |= events;
+}
+
+void PhysicalSocket::DisableEvents(uint8_t events) {
+  enabled_events_ &= ~events;
+}
+
+int PhysicalSocket::TranslateOption(Option opt, int* slevel, int* sopt) {
+  switch (opt) {
+    case OPT_DONTFRAGMENT:
+#if defined(WEBRTC_WIN)
+      *slevel = IPPROTO_IP;
+      *sopt = IP_DONTFRAGMENT;
+      break;
+#elif defined(WEBRTC_MAC) || defined(WEBRTC_BSD) || defined(__native_client__)
+      RTC_LOG(LS_WARNING) << "Socket::OPT_DONTFRAGMENT not supported.";
+      return -1;
+#elif defined(WEBRTC_POSIX)
+      *slevel = IPPROTO_IP;
+      *sopt = IP_MTU_DISCOVER;
+      break;
+#endif
+    case OPT_RCVBUF:
+      *slevel = SOL_SOCKET;
+      *sopt = SO_RCVBUF;
+      break;
+    case OPT_SNDBUF:
+      *slevel = SOL_SOCKET;
+      *sopt = SO_SNDBUF;
+      break;
+    case OPT_NODELAY:
+      *slevel = IPPROTO_TCP;
+      *sopt = TCP_NODELAY;
+      break;
+    case OPT_DSCP:
+#if defined(WEBRTC_POSIX)
+      if (family_ == AF_INET6) {
+        *slevel = IPPROTO_IPV6;
+        *sopt = IPV6_TCLASS;
+      } else {
+        *slevel = IPPROTO_IP;
+        *sopt = IP_TOS;
+      }
+      break;
+#else
+      RTC_LOG(LS_WARNING) << "Socket::OPT_DSCP not supported.";
+      return -1;
+#endif
+    case OPT_RTP_SENDTIME_EXTN_ID:
+      return -1;  // No logging is necessary as this not a OS socket option.
+    default:
+      RTC_DCHECK_NOTREACHED();
+      return -1;
+  }
+  return 0;
+}
+
+SocketDispatcher::SocketDispatcher(PhysicalSocketServer* ss)
+#if defined(WEBRTC_WIN)
+    : PhysicalSocket(ss),
+      id_(0),
+      signal_close_(false)
+#else
+    : PhysicalSocket(ss)
+#endif
+{
+}
+
+SocketDispatcher::SocketDispatcher(SOCKET s, PhysicalSocketServer* ss)
+#if defined(WEBRTC_WIN)
+    : PhysicalSocket(ss, s),
+      id_(0),
+      signal_close_(false)
+#else
+    : PhysicalSocket(ss, s)
+#endif
+{
+}
+
+SocketDispatcher::~SocketDispatcher() {
+  Close();
+}
+
+bool SocketDispatcher::Initialize() {
+  RTC_DCHECK(s_ != INVALID_SOCKET);
+// Must be a non-blocking
+#if defined(WEBRTC_WIN)
+  u_long argp = 1;
+  ioctlsocket(s_, FIONBIO, &argp);
+#elif defined(WEBRTC_POSIX)
+  fcntl(s_, F_SETFL, fcntl(s_, F_GETFL, 0) | O_NONBLOCK);
+  if (!IsScmTimeStampExperimentDisabled()) {
+    int value = 1;
+    // Attempt to get receive packet timestamp from the socket.
+    if (::setsockopt(s_, SOL_SOCKET, SO_TIMESTAMP, &value, sizeof(value)) !=
+        0) {
+      RTC_DLOG(LS_ERROR) << "::setsockopt failed. errno: " << LAST_SYSTEM_ERROR;
+    }
+  }
+#endif
+
+#if defined(WEBRTC_IOS)
+  // iOS may kill sockets when the app is moved to the background
+  // (specifically, if the app doesn't use the "voip" UIBackgroundMode). When
+  // we attempt to write to such a socket, SIGPIPE will be raised, which by
+  // default will terminate the process, which we don't want. By specifying
+  // this socket option, SIGPIPE will be disabled for the socket.
+  int value = 1;
+  if (::setsockopt(s_, SOL_SOCKET, SO_NOSIGPIPE, &value, sizeof(value)) != 0) {
+    RTC_DLOG(LS_ERROR) << "::setsockopt failed. errno: " << LAST_SYSTEM_ERROR;
+  }
+#endif
+  ss_->Add(this);
+  return true;
+}
+
+bool SocketDispatcher::Create(int type) {
+  return Create(AF_INET, type);
+}
+
+bool SocketDispatcher::Create(int family, int type) {
+  // Change the socket to be non-blocking.
+  if (!PhysicalSocket::Create(family, type))
+    return false;
+
+  if (!Initialize())
+    return false;
+
+#if defined(WEBRTC_WIN)
+  do {
+    id_ = ++next_id_;
+  } while (id_ == 0);
+#endif
+  return true;
+}
+
+#if defined(WEBRTC_WIN)
+
+WSAEVENT SocketDispatcher::GetWSAEvent() {
+  return WSA_INVALID_EVENT;
+}
+
+SOCKET SocketDispatcher::GetSocket() {
+  return s_;
+}
+
+bool SocketDispatcher::CheckSignalClose() {
+  if (!signal_close_)
+    return false;
+
+  char ch;
+  if (recv(s_, &ch, 1, MSG_PEEK) > 0)
+    return false;
+
+  state_ = CS_CLOSED;
+  signal_close_ = false;
+  SignalCloseEvent(this, signal_err_);
+  return true;
+}
+
+int SocketDispatcher::next_id_ = 0;
+
+#elif defined(WEBRTC_POSIX)
+
+int SocketDispatcher::GetDescriptor() {
+  return s_;
+}
+
+bool SocketDispatcher::IsDescriptorClosed() {
+  if (udp_) {
+    // The MSG_PEEK trick doesn't work for UDP, since (at least in some
+    // circumstances) it requires reading an entire UDP packet, which would be
+    // bad for performance here. So, just check whether `s_` has been closed,
+    // which should be sufficient.
+    return s_ == INVALID_SOCKET;
+  }
+  // We don't have a reliable way of distinguishing end-of-stream
+  // from readability.  So test on each readable call.  Is this
+  // inefficient?  Probably.
+  char ch;
+  ssize_t res;
+  // Retry if the system call was interrupted.
+  do {
+    res = ::recv(s_, &ch, 1, MSG_PEEK);
+  } while (res < 0 && errno == EINTR);
+  if (res > 0) {
+    // Data available, so not closed.
+    return false;
+  } else if (res == 0) {
+    // EOF, so closed.
+    return true;
+  } else {  // error
+    switch (errno) {
+      // Returned if we've already closed s_.
+      case EBADF:
+        // This is dangerous: if we keep attempting to access a FD after close,
+        // it could be reopened by something else making us think it's still
+        // open. Note that this is only a DCHECK.
+        RTC_DCHECK_NOTREACHED();
+        return true;
+      // Returned during ungraceful peer shutdown.
+      case ECONNRESET:
+        return true;
+      case ECONNABORTED:
+        return true;
+      case EPIPE:
+        return true;
+      // The normal blocking error; don't log anything.
+      case EWOULDBLOCK:
+        return false;
+      default:
+        // Assume that all other errors are just blocking errors, meaning the
+        // connection is still good but we just can't read from it right now.
+        // This should only happen when connecting (and at most once), because
+        // in all other cases this function is only called if the file
+        // descriptor is already known to be in the readable state. However,
+        // it's not necessary a problem if we spuriously interpret a
+        // "connection lost"-type error as a blocking error, because typically
+        // the next recv() will get EOF, so we'll still eventually notice that
+        // the socket is closed.
+        RTC_LOG_ERR(LS_WARNING) << "Assuming benign blocking error";
+        return false;
+    }
+  }
+}
+
+#endif  // WEBRTC_POSIX
+
+uint32_t SocketDispatcher::GetRequestedEvents() {
+  return enabled_events();
+}
+
+#if defined(WEBRTC_WIN)
+
+void SocketDispatcher::OnEvent(uint32_t ff, int err) {
+  if ((ff & DE_CONNECT) != 0)
+    state_ = CS_CONNECTED;
+
+  // We set CS_CLOSED from CheckSignalClose.
+
+  int cache_id = id_;
+  // Make sure we deliver connect/accept first. Otherwise, consumers may see
+  // something like a READ followed by a CONNECT, which would be odd.
+  if (((ff & DE_CONNECT) != 0) && (id_ == cache_id)) {
+    if (ff != DE_CONNECT)
+      RTC_LOG(LS_VERBOSE) << "Signalled with DE_CONNECT: " << ff;
+    DisableEvents(DE_CONNECT);
+#if !defined(NDEBUG)
+    dbg_addr_ = "Connected @ ";
+    dbg_addr_.append(GetRemoteAddress().ToString());
+#endif
+    SignalConnectEvent(this);
+  }
+  if (((ff & DE_ACCEPT) != 0) && (id_ == cache_id)) {
+    DisableEvents(DE_ACCEPT);
+    SignalReadEvent(this);
+  }
+  if ((ff & DE_READ) != 0) {
+    DisableEvents(DE_READ);
+    SignalReadEvent(this);
+  }
+  if (((ff & DE_WRITE) != 0) && (id_ == cache_id)) {
+    DisableEvents(DE_WRITE);
+    SignalWriteEvent(this);
+  }
+  if (((ff & DE_CLOSE) != 0) && (id_ == cache_id)) {
+    signal_close_ = true;
+    signal_err_ = err;
+  }
+}
+
+#elif defined(WEBRTC_POSIX)
+
+void SocketDispatcher::OnEvent(uint32_t ff, int err) {
+  if ((ff & DE_CONNECT) != 0)
+    state_ = CS_CONNECTED;
+
+  if ((ff & DE_CLOSE) != 0)
+    state_ = CS_CLOSED;
+
+#if defined(WEBRTC_USE_EPOLL)
+  // Remember currently enabled events so we can combine multiple changes
+  // into one update call later.
+  // The signal handlers might re-enable events disabled here, so we can't
+  // keep a list of events to disable at the end of the method. This list
+  // would not be updated with the events enabled by the signal handlers.
+  StartBatchedEventUpdates();
+#endif
+  // Make sure we deliver connect/accept first. Otherwise, consumers may see
+  // something like a READ followed by a CONNECT, which would be odd.
+  if ((ff & DE_CONNECT) != 0) {
+    DisableEvents(DE_CONNECT);
+    SignalConnectEvent(this);
+  }
+  if ((ff & DE_ACCEPT) != 0) {
+    DisableEvents(DE_ACCEPT);
+    SignalReadEvent(this);
+  }
+  if ((ff & DE_READ) != 0) {
+    DisableEvents(DE_READ);
+    SignalReadEvent(this);
+  }
+  if ((ff & DE_WRITE) != 0) {
+    DisableEvents(DE_WRITE);
+    SignalWriteEvent(this);
+  }
+  if ((ff & DE_CLOSE) != 0) {
+    // The socket is now dead to us, so stop checking it.
+    SetEnabledEvents(0);
+    SignalCloseEvent(this, err);
+  }
+#if defined(WEBRTC_USE_EPOLL)
+  FinishBatchedEventUpdates();
+#endif
+}
+
+#endif  // WEBRTC_POSIX
+
+#if defined(WEBRTC_USE_EPOLL)
+
+inline static int GetEpollEvents(uint32_t ff) {
+  int events = 0;
+  if (ff & (DE_READ | DE_ACCEPT)) {
+    events |= EPOLLIN;
+  }
+  if (ff & (DE_WRITE | DE_CONNECT)) {
+    events |= EPOLLOUT;
+  }
+  return events;
+}
+
+void SocketDispatcher::StartBatchedEventUpdates() {
+  RTC_DCHECK_EQ(saved_enabled_events_, -1);
+  saved_enabled_events_ = enabled_events();
+}
+
+void SocketDispatcher::FinishBatchedEventUpdates() {
+  RTC_DCHECK_NE(saved_enabled_events_, -1);
+  uint8_t old_events = static_cast<uint8_t>(saved_enabled_events_);
+  saved_enabled_events_ = -1;
+  MaybeUpdateDispatcher(old_events);
+}
+
+void SocketDispatcher::MaybeUpdateDispatcher(uint8_t old_events) {
+  if (GetEpollEvents(enabled_events()) != GetEpollEvents(old_events) &&
+      saved_enabled_events_ == -1) {
+    ss_->Update(this);
+  }
+}
+
+void SocketDispatcher::SetEnabledEvents(uint8_t events) {
+  uint8_t old_events = enabled_events();
+  PhysicalSocket::SetEnabledEvents(events);
+  MaybeUpdateDispatcher(old_events);
+}
+
+void SocketDispatcher::EnableEvents(uint8_t events) {
+  uint8_t old_events = enabled_events();
+  PhysicalSocket::EnableEvents(events);
+  MaybeUpdateDispatcher(old_events);
+}
+
+void SocketDispatcher::DisableEvents(uint8_t events) {
+  uint8_t old_events = enabled_events();
+  PhysicalSocket::DisableEvents(events);
+  MaybeUpdateDispatcher(old_events);
+}
+
+#endif  // WEBRTC_USE_EPOLL
+
+int SocketDispatcher::Close() {
+  if (s_ == INVALID_SOCKET)
+    return 0;
+
+#if defined(WEBRTC_WIN)
+  id_ = 0;
+  signal_close_ = false;
+#endif
+#if defined(WEBRTC_USE_EPOLL)
+  // If we're batching events, the socket can be closed and reopened
+  // during the batch. Set saved_enabled_events_ to 0 here so the new
+  // socket, if any, has the correct old events bitfield
+  if (saved_enabled_events_ != -1) {
+    saved_enabled_events_ = 0;
+  }
+#endif
+  ss_->Remove(this);
+  return PhysicalSocket::Close();
+}
+
+#if defined(WEBRTC_POSIX)
+// Sets the value of a boolean value to false when signaled.
+class Signaler : public Dispatcher {
+ public:
+  Signaler(PhysicalSocketServer* ss, bool& flag_to_clear)
+      : ss_(ss),
+        afd_([] {
+          std::array<int, 2> afd = {-1, -1};
+
+          if (pipe(afd.data()) < 0) {
+            RTC_LOG(LS_ERROR) << "pipe failed";
+          }
+          return afd;
+        }()),
+        fSignaled_(false),
+        flag_to_clear_(flag_to_clear) {
+    ss_->Add(this);
+  }
+
+  ~Signaler() override {
+    ss_->Remove(this);
+    close(afd_[0]);
+    close(afd_[1]);
+  }
+
+  virtual void Signal() {
+    webrtc::MutexLock lock(&mutex_);
+    if (!fSignaled_) {
+      const uint8_t b[1] = {0};
+      const ssize_t res = write(afd_[1], b, sizeof(b));
+      RTC_DCHECK_EQ(1, res);
+      fSignaled_ = true;
+    }
+  }
+
+  uint32_t GetRequestedEvents() override { return DE_READ; }
+
+  void OnEvent(uint32_t ff, int err) override {
+    // It is not possible to perfectly emulate an auto-resetting event with
+    // pipes.  This simulates it by resetting before the event is handled.
+
+    webrtc::MutexLock lock(&mutex_);
+    if (fSignaled_) {
+      uint8_t b[4];  // Allow for reading more than 1 byte, but expect 1.
+      const ssize_t res = read(afd_[0], b, sizeof(b));
+      RTC_DCHECK_EQ(1, res);
+      fSignaled_ = false;
+    }
+    flag_to_clear_ = false;
+  }
+
+  int GetDescriptor() override { return afd_[0]; }
+
+  bool IsDescriptorClosed() override { return false; }
+
+ private:
+  PhysicalSocketServer* const ss_;
+  const std::array<int, 2> afd_;
+  bool fSignaled_ RTC_GUARDED_BY(mutex_);
+  webrtc::Mutex mutex_;
+  bool& flag_to_clear_;
+};
+
+#endif  // WEBRTC_POSIX
+
+#if defined(WEBRTC_WIN)
+static uint32_t FlagsToEvents(uint32_t events) {
+  uint32_t ffFD = FD_CLOSE;
+  if (events & DE_READ)
+    ffFD |= FD_READ;
+  if (events & DE_WRITE)
+    ffFD |= FD_WRITE;
+  if (events & DE_CONNECT)
+    ffFD |= FD_CONNECT;
+  if (events & DE_ACCEPT)
+    ffFD |= FD_ACCEPT;
+  return ffFD;
+}
+
+// Sets the value of a boolean value to false when signaled.
+class Signaler : public Dispatcher {
+ public:
+  Signaler(PhysicalSocketServer* ss, bool& flag_to_clear)
+      : ss_(ss), flag_to_clear_(flag_to_clear) {
+    hev_ = WSACreateEvent();
+    if (hev_) {
+      ss_->Add(this);
+    }
+  }
+
+  ~Signaler() override {
+    if (hev_ != nullptr) {
+      ss_->Remove(this);
+      WSACloseEvent(hev_);
+      hev_ = nullptr;
+    }
+  }
+
+  virtual void Signal() {
+    if (hev_ != nullptr)
+      WSASetEvent(hev_);
+  }
+
+  uint32_t GetRequestedEvents() override { return 0; }
+
+  void OnEvent(uint32_t ff, int err) override {
+    WSAResetEvent(hev_);
+    flag_to_clear_ = false;
+  }
+
+  WSAEVENT GetWSAEvent() override { return hev_; }
+
+  SOCKET GetSocket() override { return INVALID_SOCKET; }
+
+  bool CheckSignalClose() override { return false; }
+
+ private:
+  PhysicalSocketServer* ss_;
+  WSAEVENT hev_;
+  bool& flag_to_clear_;
+};
+#endif  // WEBRTC_WIN
+
+PhysicalSocketServer::PhysicalSocketServer()
+    :
+#if defined(WEBRTC_USE_EPOLL)
+      // Since Linux 2.6.8, the size argument is ignored, but must be greater
+      // than zero. Before that the size served as hint to the kernel for the
+      // amount of space to initially allocate in internal data structures.
+      epoll_fd_(epoll_create(FD_SETSIZE)),
+#endif
+#if defined(WEBRTC_WIN)
+      socket_ev_(WSACreateEvent()),
+#endif
+      fWait_(false) {
+#if defined(WEBRTC_USE_EPOLL)
+  if (epoll_fd_ == -1) {
+    // Not an error, will fall back to "select" below.
+    RTC_LOG_E(LS_WARNING, EN, errno) << "epoll_create";
+    // Note that -1 == INVALID_SOCKET, the alias used by later checks.
+  }
+#endif
+  // The `fWait_` flag to be cleared by the Signaler.
+  signal_wakeup_ = new Signaler(this, fWait_);
+}
+
+PhysicalSocketServer::~PhysicalSocketServer() {
+#if defined(WEBRTC_WIN)
+  WSACloseEvent(socket_ev_);
+#endif
+  delete signal_wakeup_;
+#if defined(WEBRTC_USE_EPOLL)
+  if (epoll_fd_ != INVALID_SOCKET) {
+    close(epoll_fd_);
+  }
+#endif
+  RTC_DCHECK(dispatcher_by_key_.empty());
+  RTC_DCHECK(key_by_dispatcher_.empty());
+}
+
+void PhysicalSocketServer::WakeUp() {
+  signal_wakeup_->Signal();
+}
+
+Socket* PhysicalSocketServer::CreateSocket(int family, int type) {
+  SocketDispatcher* dispatcher = new SocketDispatcher(this);
+  if (dispatcher->Create(family, type)) {
+    return dispatcher;
+  } else {
+    delete dispatcher;
+    return nullptr;
+  }
+}
+
+Socket* PhysicalSocketServer::WrapSocket(SOCKET s) {
+  SocketDispatcher* dispatcher = new SocketDispatcher(s, this);
+  if (dispatcher->Initialize()) {
+    return dispatcher;
+  } else {
+    delete dispatcher;
+    return nullptr;
+  }
+}
+
+void PhysicalSocketServer::Add(Dispatcher* pdispatcher) {
+  CritScope cs(&crit_);
+  if (key_by_dispatcher_.count(pdispatcher)) {
+    RTC_LOG(LS_WARNING)
+        << "PhysicalSocketServer asked to add a duplicate dispatcher.";
+    return;
+  }
+  uint64_t key = next_dispatcher_key_++;
+  dispatcher_by_key_.emplace(key, pdispatcher);
+  key_by_dispatcher_.emplace(pdispatcher, key);
+#if defined(WEBRTC_USE_EPOLL)
+  if (epoll_fd_ != INVALID_SOCKET) {
+    AddEpoll(pdispatcher, key);
+  }
+#endif  // WEBRTC_USE_EPOLL
+}
+
+void PhysicalSocketServer::Remove(Dispatcher* pdispatcher) {
+  CritScope cs(&crit_);
+  if (!key_by_dispatcher_.count(pdispatcher)) {
+    RTC_LOG(LS_WARNING)
+        << "PhysicalSocketServer asked to remove a unknown "
+           "dispatcher, potentially from a duplicate call to Add.";
+    return;
+  }
+  uint64_t key = key_by_dispatcher_.at(pdispatcher);
+  key_by_dispatcher_.erase(pdispatcher);
+  dispatcher_by_key_.erase(key);
+#if defined(WEBRTC_USE_EPOLL)
+  if (epoll_fd_ != INVALID_SOCKET) {
+    RemoveEpoll(pdispatcher);
+  }
+#endif  // WEBRTC_USE_EPOLL
+}
+
+void PhysicalSocketServer::Update(Dispatcher* pdispatcher) {
+#if defined(WEBRTC_USE_EPOLL)
+  if (epoll_fd_ == INVALID_SOCKET) {
+    return;
+  }
+
+  // Don't update dispatchers that haven't yet been added.
+  CritScope cs(&crit_);
+  if (!key_by_dispatcher_.count(pdispatcher)) {
+    return;
+  }
+
+  UpdateEpoll(pdispatcher, key_by_dispatcher_.at(pdispatcher));
+#endif
+}
+
+int PhysicalSocketServer::ToCmsWait(webrtc::TimeDelta max_wait_duration) {
+  return max_wait_duration == Event::kForever
+             ? kForeverMs
+             : max_wait_duration.RoundUpTo(webrtc::TimeDelta::Millis(1)).ms();
+}
+
+#if defined(WEBRTC_POSIX)
+
+bool PhysicalSocketServer::Wait(webrtc::TimeDelta max_wait_duration,
+                                bool process_io) {
+  // We don't support reentrant waiting.
+  RTC_DCHECK(!waiting_);
+  ScopedSetTrue s(&waiting_);
+  const int cmsWait = ToCmsWait(max_wait_duration);
+
+#if defined(WEBRTC_USE_POLL)
+  return WaitPoll(cmsWait, process_io);
+#else
+#if defined(WEBRTC_USE_EPOLL)
+  // We don't keep a dedicated "epoll" descriptor containing only the non-IO
+  // (i.e. signaling) dispatcher, so "poll" will be used instead of the default
+  // "select" to support sockets larger than FD_SETSIZE.
+  if (!process_io) {
+    return WaitPollOneDispatcher(cmsWait, signal_wakeup_);
+  } else if (epoll_fd_ != INVALID_SOCKET) {
+    return WaitEpoll(cmsWait);
+  }
+#endif
+  return WaitSelect(cmsWait, process_io);
+#endif
+}
+
+// `error_event` is true if we are responding to an event where we know an
+// error has occurred, which is possible with the poll/epoll implementations
+// but not the select implementation.
+//
+// `check_error` is true if there is the possibility of an error.
+static void ProcessEvents(Dispatcher* dispatcher,
+                          bool readable,
+                          bool writable,
+                          bool error_event,
+                          bool check_error) {
+  RTC_DCHECK(!(error_event && !check_error));
+  int errcode = 0;
+  if (check_error) {
+    socklen_t len = sizeof(errcode);
+    int res = ::getsockopt(dispatcher->GetDescriptor(), SOL_SOCKET, SO_ERROR,
+                           &errcode, &len);
+    if (res < 0) {
+      // If we are sure an error has occurred, or if getsockopt failed for a
+      // socket descriptor, make sure we set the error code to a nonzero value.
+      if (error_event || errno != ENOTSOCK) {
+        errcode = EBADF;
+      }
+    }
+  }
+
+  // Most often the socket is writable or readable or both, so make a single
+  // virtual call to get requested events
+  const uint32_t requested_events = dispatcher->GetRequestedEvents();
+  uint32_t ff = 0;
+
+  // Check readable descriptors. If we're waiting on an accept, signal
+  // that. Otherwise we're waiting for data, check to see if we're
+  // readable or really closed.
+  // TODO(pthatcher): Only peek at TCP descriptors.
+  if (readable) {
+    if (errcode || dispatcher->IsDescriptorClosed()) {
+      ff |= DE_CLOSE;
+    } else if (requested_events & DE_ACCEPT) {
+      ff |= DE_ACCEPT;
+    } else {
+      ff |= DE_READ;
+    }
+  }
+
+  // Check writable descriptors. If we're waiting on a connect, detect
+  // success versus failure by the reaped error code.
+  if (writable) {
+    if (requested_events & DE_CONNECT) {
+      if (!errcode) {
+        ff |= DE_CONNECT;
+      }
+    } else {
+      ff |= DE_WRITE;
+    }
+  }
+
+  // Make sure we report any errors regardless of whether readable or writable.
+  if (errcode) {
+    ff |= DE_CLOSE;
+  }
+
+  // Tell the descriptor about the event.
+  if (ff != 0) {
+    dispatcher->OnEvent(ff, errcode);
+  }
+}
+
+#if defined(WEBRTC_USE_POLL) || defined(WEBRTC_USE_EPOLL)
+static void ProcessPollEvents(Dispatcher* dispatcher, const pollfd& pfd) {
+  bool readable = (pfd.revents & (POLLIN | POLLPRI));
+  bool writable = (pfd.revents & POLLOUT);
+  bool error = (pfd.revents & (POLLRDHUP | POLLERR | POLLHUP));
+
+  ProcessEvents(dispatcher, readable, writable, error, error);
+}
+
+static pollfd DispatcherToPollfd(Dispatcher* dispatcher) {
+  pollfd fd{
+      .fd = dispatcher->GetDescriptor(),
+      .events = 0,
+      .revents = 0,
+  };
+
+  uint32_t ff = dispatcher->GetRequestedEvents();
+  if (ff & (DE_READ | DE_ACCEPT)) {
+    fd.events |= POLLIN;
+  }
+  if (ff & (DE_WRITE | DE_CONNECT)) {
+    fd.events |= POLLOUT;
+  }
+
+  return fd;
+}
+#endif  // WEBRTC_USE_POLL || WEBRTC_USE_EPOLL
+
+bool PhysicalSocketServer::WaitSelect(int cmsWait, bool process_io) {
+  // Calculate timing information
+
+  struct timeval* ptvWait = nullptr;
+  struct timeval tvWait;
+  int64_t stop_us;
+  if (cmsWait != kForeverMs) {
+    // Calculate wait timeval
+    tvWait.tv_sec = cmsWait / 1000;
+    tvWait.tv_usec = (cmsWait % 1000) * 1000;
+    ptvWait = &tvWait;
+
+    // Calculate when to return
+    stop_us = rtc::TimeMicros() + cmsWait * 1000;
+  }
+
+  fd_set fdsRead;
+  fd_set fdsWrite;
+// Explicitly unpoison these FDs on MemorySanitizer which doesn't handle the
+// inline assembly in FD_ZERO.
+// http://crbug.com/344505
+#ifdef MEMORY_SANITIZER
+  __msan_unpoison(&fdsRead, sizeof(fdsRead));
+  __msan_unpoison(&fdsWrite, sizeof(fdsWrite));
+#endif
+
+  fWait_ = true;
+
+  while (fWait_) {
+    // Zero all fd_sets. Although select() zeros the descriptors not signaled,
+    // we may need to do this for dispatchers that were deleted while
+    // iterating.
+    FD_ZERO(&fdsRead);
+    FD_ZERO(&fdsWrite);
+    int fdmax = -1;
+    {
+      CritScope cr(&crit_);
+      current_dispatcher_keys_.clear();
+      for (auto const& kv : dispatcher_by_key_) {
+        uint64_t key = kv.first;
+        Dispatcher* pdispatcher = kv.second;
+        if (!process_io && (pdispatcher != signal_wakeup_))
+          continue;
+        current_dispatcher_keys_.push_back(key);
+        int fd = pdispatcher->GetDescriptor();
+        // "select"ing a file descriptor that is equal to or larger than
+        // FD_SETSIZE will result in undefined behavior.
+        RTC_CHECK_LT(fd, FD_SETSIZE);
+        if (fd > fdmax)
+          fdmax = fd;
+
+        uint32_t ff = pdispatcher->GetRequestedEvents();
+        if (ff & (DE_READ | DE_ACCEPT))
+          FD_SET(fd, &fdsRead);
+        if (ff & (DE_WRITE | DE_CONNECT))
+          FD_SET(fd, &fdsWrite);
+      }
+    }
+
+    // Wait then call handlers as appropriate
+    // < 0 means error
+    // 0 means timeout
+    // > 0 means count of descriptors ready
+    int n = select(fdmax + 1, &fdsRead, &fdsWrite, nullptr, ptvWait);
+
+    // If error, return error.
+    if (n < 0) {
+      if (errno != EINTR) {
+        RTC_LOG_E(LS_ERROR, EN, errno) << "select";
+        return false;
+      }
+      // Else ignore the error and keep going. If this EINTR was for one of the
+      // signals managed by this PhysicalSocketServer, the
+      // PosixSignalDeliveryDispatcher will be in the signaled state in the next
+      // iteration.
+    } else if (n == 0) {
+      // If timeout, return success
+      return true;
+    } else {
+      // We have signaled descriptors
+      CritScope cr(&crit_);
+      // Iterate only on the dispatchers whose file descriptors were passed into
+      // select; this avoids the ABA problem (a socket being destroyed and a new
+      // one created with the same file descriptor).
+      for (uint64_t key : current_dispatcher_keys_) {
+        if (!dispatcher_by_key_.count(key))
+          continue;
+        Dispatcher* pdispatcher = dispatcher_by_key_.at(key);
+
+        int fd = pdispatcher->GetDescriptor();
+
+        bool readable = FD_ISSET(fd, &fdsRead);
+        if (readable) {
+          FD_CLR(fd, &fdsRead);
+        }
+
+        bool writable = FD_ISSET(fd, &fdsWrite);
+        if (writable) {
+          FD_CLR(fd, &fdsWrite);
+        }
+
+        // The error code can be signaled through reads or writes.
+        ProcessEvents(pdispatcher, readable, writable, /*error_event=*/false,
+                      readable || writable);
+      }
+    }
+
+    // Recalc the time remaining to wait. Doing it here means it doesn't get
+    // calced twice the first time through the loop
+    if (ptvWait) {
+      ptvWait->tv_sec = 0;
+      ptvWait->tv_usec = 0;
+      int64_t time_left_us = stop_us - rtc::TimeMicros();
+      if (time_left_us > 0) {
+        ptvWait->tv_sec = time_left_us / rtc::kNumMicrosecsPerSec;
+        ptvWait->tv_usec = time_left_us % rtc::kNumMicrosecsPerSec;
+      }
+    }
+  }
+
+  return true;
+}
+
+#if defined(WEBRTC_USE_EPOLL)
+
+void PhysicalSocketServer::AddEpoll(Dispatcher* pdispatcher, uint64_t key) {
+  RTC_DCHECK(epoll_fd_ != INVALID_SOCKET);
+  int fd = pdispatcher->GetDescriptor();
+  RTC_DCHECK(fd != INVALID_SOCKET);
+  if (fd == INVALID_SOCKET) {
+    return;
+  }
+
+  struct epoll_event event = {0};
+  event.events = GetEpollEvents(pdispatcher->GetRequestedEvents());
+  if (event.events == 0u) {
+    // Don't add at all if we don't have any requested events. Could indicate a
+    // closed socket.
+    return;
+  }
+  event.data.u64 = key;
+  int err = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &event);
+  RTC_DCHECK_EQ(err, 0);
+  if (err == -1) {
+    RTC_LOG_E(LS_ERROR, EN, errno) << "epoll_ctl EPOLL_CTL_ADD";
+  }
+}
+
+void PhysicalSocketServer::RemoveEpoll(Dispatcher* pdispatcher) {
+  RTC_DCHECK(epoll_fd_ != INVALID_SOCKET);
+  int fd = pdispatcher->GetDescriptor();
+  RTC_DCHECK(fd != INVALID_SOCKET);
+  if (fd == INVALID_SOCKET) {
+    return;
+  }
+
+  struct epoll_event event = {0};
+  int err = epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, &event);
+  RTC_DCHECK(err == 0 || errno == ENOENT);
+  // Ignore ENOENT, which could occur if this descriptor wasn't added due to
+  // having no requested events.
+  if (err == -1 && errno != ENOENT) {
+    RTC_LOG_E(LS_ERROR, EN, errno) << "epoll_ctl EPOLL_CTL_DEL";
+  }
+}
+
+void PhysicalSocketServer::UpdateEpoll(Dispatcher* pdispatcher, uint64_t key) {
+  RTC_DCHECK(epoll_fd_ != INVALID_SOCKET);
+  int fd = pdispatcher->GetDescriptor();
+  RTC_DCHECK(fd != INVALID_SOCKET);
+  if (fd == INVALID_SOCKET) {
+    return;
+  }
+
+  struct epoll_event event = {0};
+  event.events = GetEpollEvents(pdispatcher->GetRequestedEvents());
+  event.data.u64 = key;
+  // Remove if we don't have any requested events. Could indicate a closed
+  // socket.
+  if (event.events == 0u) {
+    epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, &event);
+  } else {
+    int err = epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, fd, &event);
+    RTC_DCHECK(err == 0 || errno == ENOENT);
+    if (err == -1) {
+      // Could have been removed earlier due to no requested events.
+      if (errno == ENOENT) {
+        err = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &event);
+        if (err == -1) {
+          RTC_LOG_E(LS_ERROR, EN, errno) << "epoll_ctl EPOLL_CTL_ADD";
+        }
+      } else {
+        RTC_LOG_E(LS_ERROR, EN, errno) << "epoll_ctl EPOLL_CTL_MOD";
+      }
+    }
+  }
+}
+
+bool PhysicalSocketServer::WaitEpoll(int cmsWait) {
+  RTC_DCHECK(epoll_fd_ != INVALID_SOCKET);
+  int64_t msWait = -1;
+  int64_t msStop = -1;
+  if (cmsWait != kForeverMs) {
+    msWait = cmsWait;
+    msStop = TimeAfter(cmsWait);
+  }
+
+  fWait_ = true;
+  while (fWait_) {
+    // Wait then call handlers as appropriate
+    // < 0 means error
+    // 0 means timeout
+    // > 0 means count of descriptors ready
+    int n = epoll_wait(epoll_fd_, epoll_events_.data(), epoll_events_.size(),
+                       static_cast<int>(msWait));
+    if (n < 0) {
+      if (errno != EINTR) {
+        RTC_LOG_E(LS_ERROR, EN, errno) << "epoll";
+        return false;
+      }
+      // Else ignore the error and keep going. If this EINTR was for one of the
+      // signals managed by this PhysicalSocketServer, the
+      // PosixSignalDeliveryDispatcher will be in the signaled state in the next
+      // iteration.
+    } else if (n == 0) {
+      // If timeout, return success
+      return true;
+    } else {
+      // We have signaled descriptors
+      CritScope cr(&crit_);
+      for (int i = 0; i < n; ++i) {
+        const epoll_event& event = epoll_events_[i];
+        uint64_t key = event.data.u64;
+        if (!dispatcher_by_key_.count(key)) {
+          // The dispatcher for this socket no longer exists.
+          continue;
+        }
+        Dispatcher* pdispatcher = dispatcher_by_key_.at(key);
+
+        bool readable = (event.events & (EPOLLIN | EPOLLPRI));
+        bool writable = (event.events & EPOLLOUT);
+        bool error = (event.events & (EPOLLRDHUP | EPOLLERR | EPOLLHUP));
+
+        ProcessEvents(pdispatcher, readable, writable, error, error);
+      }
+    }
+
+    if (cmsWait != kForeverMs) {
+      msWait = TimeDiff(msStop, TimeMillis());
+      if (msWait <= 0) {
+        // Return success on timeout.
+        return true;
+      }
+    }
+  }
+
+  return true;
+}
+
+bool PhysicalSocketServer::WaitPollOneDispatcher(int cmsWait,
+                                                 Dispatcher* dispatcher) {
+  RTC_DCHECK(dispatcher);
+  int64_t msWait = -1;
+  int64_t msStop = -1;
+  if (cmsWait != kForeverMs) {
+    msWait = cmsWait;
+    msStop = TimeAfter(cmsWait);
+  }
+
+  fWait_ = true;
+  const int fd = dispatcher->GetDescriptor();
+
+  while (fWait_) {
+    auto fds = DispatcherToPollfd(dispatcher);
+
+    // Wait then call handlers as appropriate
+    // < 0 means error
+    // 0 means timeout
+    // > 0 means count of descriptors ready
+    int n = poll(&fds, 1, static_cast<int>(msWait));
+    if (n < 0) {
+      if (errno != EINTR) {
+        RTC_LOG_E(LS_ERROR, EN, errno) << "poll";
+        return false;
+      }
+      // Else ignore the error and keep going. If this EINTR was for one of the
+      // signals managed by this PhysicalSocketServer, the
+      // PosixSignalDeliveryDispatcher will be in the signaled state in the next
+      // iteration.
+    } else if (n == 0) {
+      // If timeout, return success
+      return true;
+    } else {
+      // We have signaled descriptors (should only be the passed dispatcher).
+      RTC_DCHECK_EQ(n, 1);
+      RTC_DCHECK_EQ(fds.fd, fd);
+      ProcessPollEvents(dispatcher, fds);
+    }
+
+    if (cmsWait != kForeverMs) {
+      msWait = TimeDiff(msStop, TimeMillis());
+      if (msWait < 0) {
+        // Return success on timeout.
+        return true;
+      }
+    }
+  }
+
+  return true;
+}
+
+#elif defined(WEBRTC_USE_POLL)
+
+bool PhysicalSocketServer::WaitPoll(int cmsWait, bool process_io) {
+  int64_t msWait = -1;
+  int64_t msStop = -1;
+  if (cmsWait != kForeverMs) {
+    msWait = cmsWait;
+    msStop = TimeAfter(cmsWait);
+  }
+
+  std::vector<pollfd> pollfds;
+  fWait_ = true;
+
+  while (fWait_) {
+    {
+      CritScope cr(&crit_);
+      current_dispatcher_keys_.clear();
+      pollfds.clear();
+      pollfds.reserve(dispatcher_by_key_.size());
+
+      for (auto const& kv : dispatcher_by_key_) {
+        uint64_t key = kv.first;
+        Dispatcher* pdispatcher = kv.second;
+        if (!process_io && (pdispatcher != signal_wakeup_))
+          continue;
+        current_dispatcher_keys_.push_back(key);
+        pollfds.push_back(DispatcherToPollfd(pdispatcher));
+      }
+    }
+
+    // Wait then call handlers as appropriate
+    // < 0 means error
+    // 0 means timeout
+    // > 0 means count of descriptors ready
+    int n = poll(pollfds.data(), pollfds.size(), static_cast<int>(msWait));
+    if (n < 0) {
+      if (errno != EINTR) {
+        RTC_LOG_E(LS_ERROR, EN, errno) << "poll";
+        return false;
+      }
+      // Else ignore the error and keep going. If this EINTR was for one of the
+      // signals managed by this PhysicalSocketServer, the
+      // PosixSignalDeliveryDispatcher will be in the signaled state in the next
+      // iteration.
+    } else if (n == 0) {
+      // If timeout, return success
+      return true;
+    } else {
+      // We have signaled descriptors
+      CritScope cr(&crit_);
+      // Iterate only on the dispatchers whose file descriptors were passed into
+      // poll; this avoids the ABA problem (a socket being destroyed and a new
+      // one created with the same file descriptor).
+      for (size_t i = 0; i < current_dispatcher_keys_.size(); ++i) {
+        uint64_t key = current_dispatcher_keys_[i];
+        if (!dispatcher_by_key_.count(key))
+          continue;
+        ProcessPollEvents(dispatcher_by_key_.at(key), pollfds[i]);
+      }
+    }
+
+    if (cmsWait != kForeverMs) {
+      msWait = TimeDiff(msStop, TimeMillis());
+      if (msWait < 0) {
+        // Return success on timeout.
+        return true;
+      }
+    }
+  }
+
+  return true;
+}
+
+#endif  // WEBRTC_USE_EPOLL, WEBRTC_USE_POLL
+
+#endif  // WEBRTC_POSIX
+
+#if defined(WEBRTC_WIN)
+bool PhysicalSocketServer::Wait(webrtc::TimeDelta max_wait_duration,
+                                bool process_io) {
+  // We don't support reentrant waiting.
+  RTC_DCHECK(!waiting_);
+  ScopedSetTrue s(&waiting_);
+
+  int cmsWait = ToCmsWait(max_wait_duration);
+  int64_t cmsTotal = cmsWait;
+  int64_t cmsElapsed = 0;
+  int64_t msStart = Time();
+
+  fWait_ = true;
+  while (fWait_) {
+    std::vector<WSAEVENT> events;
+    std::vector<uint64_t> event_owners;
+
+    events.push_back(socket_ev_);
+
+    {
+      CritScope cr(&crit_);
+      // Get a snapshot of all current dispatchers; this is used to avoid the
+      // ABA problem (see later comment) and avoids the dispatcher_by_key_
+      // iterator being invalidated by calling CheckSignalClose, which may
+      // remove the dispatcher from the list.
+      current_dispatcher_keys_.clear();
+      for (auto const& kv : dispatcher_by_key_) {
+        current_dispatcher_keys_.push_back(kv.first);
+      }
+      for (uint64_t key : current_dispatcher_keys_) {
+        if (!dispatcher_by_key_.count(key)) {
+          continue;
+        }
+        Dispatcher* disp = dispatcher_by_key_.at(key);
+        if (!disp)
+          continue;
+        if (!process_io && (disp != signal_wakeup_))
+          continue;
+        SOCKET s = disp->GetSocket();
+        if (disp->CheckSignalClose()) {
+          // We just signalled close, don't poll this socket.
+        } else if (s != INVALID_SOCKET) {
+          WSAEventSelect(s, events[0],
+                         FlagsToEvents(disp->GetRequestedEvents()));
+        } else {
+          events.push_back(disp->GetWSAEvent());
+          event_owners.push_back(key);
+        }
+      }
+    }
+
+    // Which is shorter, the delay wait or the asked wait?
+
+    int64_t cmsNext;
+    if (cmsWait == kForeverMs) {
+      cmsNext = cmsWait;
+    } else {
+      cmsNext = std::max<int64_t>(0, cmsTotal - cmsElapsed);
+    }
+
+    // Wait for one of the events to signal
+    DWORD dw =
+        WSAWaitForMultipleEvents(static_cast<DWORD>(events.size()), &events[0],
+                                 false, static_cast<DWORD>(cmsNext), false);
+
+    if (dw == WSA_WAIT_FAILED) {
+      // Failed?
+      // TODO(pthatcher): need a better strategy than this!
+      WSAGetLastError();
+      RTC_DCHECK_NOTREACHED();
+      return false;
+    } else if (dw == WSA_WAIT_TIMEOUT) {
+      // Timeout?
+      return true;
+    } else {
+      // Figure out which one it is and call it
+      CritScope cr(&crit_);
+      int index = dw - WSA_WAIT_EVENT_0;
+      if (index > 0) {
+        --index;  // The first event is the socket event
+        uint64_t key = event_owners[index];
+        if (!dispatcher_by_key_.count(key)) {
+          // The dispatcher could have been removed while waiting for events.
+          continue;
+        }
+        Dispatcher* disp = dispatcher_by_key_.at(key);
+        disp->OnEvent(0, 0);
+      } else if (process_io) {
+        // Iterate only on the dispatchers whose sockets were passed into
+        // WSAEventSelect; this avoids the ABA problem (a socket being
+        // destroyed and a new one created with the same SOCKET handle).
+        for (uint64_t key : current_dispatcher_keys_) {
+          if (!dispatcher_by_key_.count(key)) {
+            continue;
+          }
+          Dispatcher* disp = dispatcher_by_key_.at(key);
+          SOCKET s = disp->GetSocket();
+          if (s == INVALID_SOCKET)
+            continue;
+
+          WSANETWORKEVENTS wsaEvents;
+          int err = WSAEnumNetworkEvents(s, events[0], &wsaEvents);
+          if (err == 0) {
+            {
+              if ((wsaEvents.lNetworkEvents & FD_READ) &&
+                  wsaEvents.iErrorCode[FD_READ_BIT] != 0) {
+                RTC_LOG(LS_WARNING)
+                    << "PhysicalSocketServer got FD_READ_BIT error "
+                    << wsaEvents.iErrorCode[FD_READ_BIT];
+              }
+              if ((wsaEvents.lNetworkEvents & FD_WRITE) &&
+                  wsaEvents.iErrorCode[FD_WRITE_BIT] != 0) {
+                RTC_LOG(LS_WARNING)
+                    << "PhysicalSocketServer got FD_WRITE_BIT error "
+                    << wsaEvents.iErrorCode[FD_WRITE_BIT];
+              }
+              if ((wsaEvents.lNetworkEvents & FD_CONNECT) &&
+                  wsaEvents.iErrorCode[FD_CONNECT_BIT] != 0) {
+                RTC_LOG(LS_WARNING)
+                    << "PhysicalSocketServer got FD_CONNECT_BIT error "
+                    << wsaEvents.iErrorCode[FD_CONNECT_BIT];
+              }
+              if ((wsaEvents.lNetworkEvents & FD_ACCEPT) &&
+                  wsaEvents.iErrorCode[FD_ACCEPT_BIT] != 0) {
+                RTC_LOG(LS_WARNING)
+                    << "PhysicalSocketServer got FD_ACCEPT_BIT error "
+                    << wsaEvents.iErrorCode[FD_ACCEPT_BIT];
+              }
+              if ((wsaEvents.lNetworkEvents & FD_CLOSE) &&
+                  wsaEvents.iErrorCode[FD_CLOSE_BIT] != 0) {
+                RTC_LOG(LS_WARNING)
+                    << "PhysicalSocketServer got FD_CLOSE_BIT error "
+                    << wsaEvents.iErrorCode[FD_CLOSE_BIT];
+              }
+            }
+            uint32_t ff = 0;
+            int errcode = 0;
+            if (wsaEvents.lNetworkEvents & FD_READ)
+              ff |= DE_READ;
+            if (wsaEvents.lNetworkEvents & FD_WRITE)
+              ff |= DE_WRITE;
+            if (wsaEvents.lNetworkEvents & FD_CONNECT) {
+              if (wsaEvents.iErrorCode[FD_CONNECT_BIT] == 0) {
+                ff |= DE_CONNECT;
+              } else {
+                ff |= DE_CLOSE;
+                errcode = wsaEvents.iErrorCode[FD_CONNECT_BIT];
+              }
+            }
+            if (wsaEvents.lNetworkEvents & FD_ACCEPT)
+              ff |= DE_ACCEPT;
+            if (wsaEvents.lNetworkEvents & FD_CLOSE) {
+              ff |= DE_CLOSE;
+              errcode = wsaEvents.iErrorCode[FD_CLOSE_BIT];
+            }
+            if (ff != 0) {
+              disp->OnEvent(ff, errcode);
+            }
+          }
+        }
+      }
+
+      // Reset the network event until new activity occurs
+      WSAResetEvent(socket_ev_);
+    }
+
+    // Break?
+    if (!fWait_)
+      break;
+    cmsElapsed = TimeSince(msStart);
+    if ((cmsWait != kForeverMs) && (cmsElapsed >= cmsWait)) {
+      break;
+    }
+  }
+
+  // Done
+  return true;
+}
+#endif  // WEBRTC_WIN
+
+}  // namespace rtc