UDP: Windows implementation using non-blocking IO

net/udp/udp_socket_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/udp/udp_socket_win.h"
 
 #include <mstcpip.h>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
@@ skipping 26 matching lines @@
 
 namespace net {
 
 // This class encapsulates all the state that has to be preserved as long as
 // there is a network IO operation in progress. If the owner UDPSocketWin
 // is destroyed while an operation is in progress, the Core is detached and it
 // lives until the operation completes and the OS doesn't reference any resource
 // declared on this class anymore.
 class UDPSocketWin::Core : public base::RefCounted<Core> {
  public:
-  explicit Core(UDPSocketWin* socket);
+  explicit Core(UDPSocketWin* socket, bool use_overlapped_io);
 
-  // Start watching for the end of a read or write operation.
+  // Start watching for the end of a read or write operation in overlapped mode.
+  // In non-blocking mode watch the signals to continure read/write.
   void WatchForRead();
   void WatchForWrite();
 
   // The UDPSocketWin is going away.
   void Detach() { socket_ = NULL; }
 
-  // The separate OVERLAPPED variables for asynchronous operation.
-  OVERLAPPED read_overlapped_;
-  OVERLAPPED write_overlapped_;
+  bool use_overlapped_io() const { return use_overlapped_io_; }
 
-  // The buffers used in Read() and Write().
-  scoped_refptr<IOBuffer> read_iobuffer_;
-  scoped_refptr<IOBuffer> write_iobuffer_;
+  OVERLAPPED* read_overlapped() { return &read_overlapped_; }
+  OVERLAPPED* write_overlapped() { return &write_overlapped_; }
 
-  // The address storage passed to WSARecvFrom().
-  SockaddrStorage recv_addr_storage_;
+  WSAEVENT read_event() const { return read_event_; }
+  WSAEVENT write_event() const { return write_event_; }
+
+  scoped_refptr<IOBuffer> read_iobuffer() const { return read_iobuffer_; }
+  scoped_refptr<IOBuffer> write_iobuffer() const { return write_iobuffer_; }
+
+  void set_read_iobuffer(scoped_refptr<IOBuffer> buf, int len) {
+    read_iobuffer_ = buf;
+    read_iobuffer_len_ = len;
+  }
+  void set_write_iobuffer(scoped_refptr<IOBuffer> buf, int len) {
+    write_iobuffer_ = buf;
+    write_iobuffer_len_ = len;
+  }
+
+  int read_iobuffer_len() const { return read_iobuffer_len_; }
+  int write_iobuffer_len() const { return write_iobuffer_len_; }
+
+  SockaddrStorage* recv_addr_storage() { return &recv_addr_storage_; }
 
  private:
   friend class base::RefCounted<Core>;
 
   class ReadDelegate : public base::win::ObjectWatcher::Delegate {
    public:
     explicit ReadDelegate(Core* core) : core_(core) {}
     virtual ~ReadDelegate() {}
 
     // base::ObjectWatcher::Delegate methods:
@@ skipping 12 matching lines @@
     virtual void OnObjectSignaled(HANDLE object);
 
    private:
     Core* const core_;
   };
 
   ~Core();
 
   // The socket that created this object.
   UDPSocketWin* socket_;
+  const bool use_overlapped_io_;
 
   // |reader_| handles the signals from |read_watcher_|.
   ReadDelegate reader_;
   // |writer_| handles the signals from |write_watcher_|.
   WriteDelegate writer_;
 
   // |read_watcher_| watches for events from Read().
   base::win::ObjectWatcher read_watcher_;
   // |write_watcher_| watches for events from Write();
   base::win::ObjectWatcher write_watcher_;
 
+  // The separate OVERLAPPED variables for asynchronous operation.
+  OVERLAPPED read_overlapped_;
+  OVERLAPPED write_overlapped_;
+
+  // Separate events for non-blocking IO operations.
+  WSAEVENT read_event_;
+  WSAEVENT write_event_;
+
+  // The buffers used in Read() and Write().
+  scoped_refptr<IOBuffer> read_iobuffer_;
+  scoped_refptr<IOBuffer> write_iobuffer_;
+  int read_iobuffer_len_;
+  int write_iobuffer_len_;
+
+  // The address storage passed to WSARecvFrom().
+  SockaddrStorage recv_addr_storage_;
+
   DISALLOW_COPY_AND_ASSIGN(Core);
 };
 
-UDPSocketWin::Core::Core(UDPSocketWin* socket)
+UDPSocketWin::Core::Core(UDPSocketWin* socket, bool use_overlapped_io)
     : socket_(socket),
+      use_overlapped_io_(use_overlapped_io),
       reader_(this),
-      writer_(this) {
+      writer_(this),
+      read_iobuffer_len_(0),
+      write_iobuffer_len_(0) {
   memset(&read_overlapped_, 0, sizeof(read_overlapped_));
   memset(&write_overlapped_, 0, sizeof(write_overlapped_));
 
-  read_overlapped_.hEvent = WSACreateEvent();
-  write_overlapped_.hEvent = WSACreateEvent();
+  if (use_overlapped_io) {
+    read_overlapped_.hEvent = WSACreateEvent();
+    write_overlapped_.hEvent = WSACreateEvent();
+  } else {
+    read_event_ = WSACreateEvent();
+    write_event_ = WSACreateEvent();
+  }
 }
 
 UDPSocketWin::Core::~Core() {
   // Make sure the message loop is not watching this object anymore.
   read_watcher_.StopWatching();
   write_watcher_.StopWatching();
 
-  WSACloseEvent(read_overlapped_.hEvent);
-  memset(&read_overlapped_, 0xaf, sizeof(read_overlapped_));
-  WSACloseEvent(write_overlapped_.hEvent);
-  memset(&write_overlapped_, 0xaf, sizeof(write_overlapped_));
+  if (use_overlapped_io_) {
+    WSACloseEvent(read_overlapped_.hEvent);
+    memset(&read_overlapped_, 0, sizeof(read_overlapped_));
+    WSACloseEvent(write_overlapped_.hEvent);
+    memset(&write_overlapped_, 0, sizeof(write_overlapped_));
+  } else {
+    WSACloseEvent(read_event_);
+    WSACloseEvent(write_event_);
+  }
 }
 
 void UDPSocketWin::Core::WatchForRead() {
   // We grab an extra reference because there is an IO operation in progress.
   // Balanced in ReadDelegate::OnObjectSignaled().
   AddRef();
-  read_watcher_.StartWatching(read_overlapped_.hEvent, &reader_);
+  if (use_overlapped_io_)
+    read_watcher_.StartWatching(read_overlapped_.hEvent, &reader_);
+  else
+    read_watcher_.StartWatching(read_event_, &reader_);
 }
 
 void UDPSocketWin::Core::WatchForWrite() {
   // We grab an extra reference because there is an IO operation in progress.
   // Balanced in WriteDelegate::OnObjectSignaled().
   AddRef();
-  write_watcher_.StartWatching(write_overlapped_.hEvent, &writer_);
+  if (use_overlapped_io_)
+    write_watcher_.StartWatching(write_overlapped_.hEvent, &writer_);
+  else
+    write_watcher_.StartWatching(write_event_, &writer_);
 }
 
 void UDPSocketWin::Core::ReadDelegate::OnObjectSignaled(HANDLE object) {
   // TODO(vadimt): Remove ScopedTracker below once crbug.com/418183 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "UDPSocketWin_Core_ReadDelegate_OnObjectSignaled"));
 
-  DCHECK_EQ(object, core_->read_overlapped_.hEvent);
-  if (core_->socket_)
-    core_->socket_->DidCompleteRead();
+  if (core_->use_overlapped_io()) {
+    DCHECK_EQ(object, core_->read_overlapped()->hEvent);
+    if (core_->socket_)
+      core_->socket_->DidCompleteReadOverlapped();
+  } else {
+    DCHECK_EQ(object, core_->read_event());
+    if (core_->socket_)
+      core_->socket_->OnReadSignaledNonBlocking();
+  }
 
   core_->Release();
 }
 
 void UDPSocketWin::Core::WriteDelegate::OnObjectSignaled(HANDLE object) {
   // TODO(vadimt): Remove ScopedTracker below once crbug.com/418183 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "UDPSocketWin_Core_WriteDelegate_OnObjectSignaled"));
 
-  DCHECK_EQ(object, core_->write_overlapped_.hEvent);
-  if (core_->socket_)
-    core_->socket_->DidCompleteWrite();
+  if (core_->use_overlapped_io()) {
+    DCHECK_EQ(object, core_->write_overlapped()->hEvent);
+    if (core_->socket_)
+      core_->socket_->DidCompleteWriteOverlapped();
+  } else {
+    DCHECK_EQ(object, core_->write_event());
+    if (core_->socket_)
+      core_->socket_->OnWriteSignaledNonBlocking();
+  }
 
   core_->Release();
 }
 //-----------------------------------------------------------------------------
 
 QwaveAPI::QwaveAPI() : qwave_supported_(false) {
   HMODULE qwave = LoadLibrary(L"qwave.dll");
   if (!qwave)
     return;
   create_handle_func_ =
@@ skipping 74 matching lines @@
                            net::NetLog* net_log,
                            const net::NetLog::Source& source)
     : socket_(INVALID_SOCKET),
       addr_family_(0),
       is_connected_(false),
       socket_options_(SOCKET_OPTION_MULTICAST_LOOP),
       multicast_interface_(0),
       multicast_time_to_live_(1),
       bind_type_(bind_type),
       rand_int_cb_(rand_int_cb),
+      non_blocking_reads_initialized_(false),
+      non_blocking_writes_initialized_(false),
       recv_from_address_(NULL),
       net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_UDP_SOCKET)),
       qos_handle_(NULL),
-      qos_flow_id_(0) {
+      qos_flow_id_(0),
+      use_overlapped_io_(true) {
   EnsureWinsockInit();
   net_log_.BeginEvent(NetLog::TYPE_SOCKET_ALIVE,
                       source.ToEventParametersCallback());
   if (bind_type == DatagramSocket::RANDOM_BIND)
     DCHECK(!rand_int_cb.is_null());
 }
 
 UDPSocketWin::~UDPSocketWin() {
   Close();
   net_log_.EndEvent(NetLog::TYPE_SOCKET_ALIVE);
 }
 
 int UDPSocketWin::Open(AddressFamily address_family) {
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(socket_, INVALID_SOCKET);
 
   addr_family_ = ConvertAddressFamily(address_family);
   socket_ = CreatePlatformSocket(addr_family_, SOCK_DGRAM, IPPROTO_UDP);
   if (socket_ == INVALID_SOCKET)
     return MapSystemError(WSAGetLastError());
-  core_ = new Core(this);
+  core_ = new Core(this, use_overlapped_io_);
   return OK;
 }
 
 void UDPSocketWin::Close() {
   DCHECK(CalledOnValidThread());
 
   if (socket_ == INVALID_SOCKET)
     return;
 
   if (qos_handle_) {
@@ skipping 71 matching lines @@
                            int buf_len,
                            IPEndPoint* address,
                            const CompletionCallback& callback) {
   DCHECK(CalledOnValidThread());
   DCHECK_NE(INVALID_SOCKET, socket_);
   CHECK(read_callback_.is_null());
   DCHECK(!recv_from_address_);
   DCHECK(!callback.is_null());  // Synchronous operation not supported.
   DCHECK_GT(buf_len, 0);
 
-  int nread = InternalRecvFrom(buf, buf_len, address);
+  int nread = use_overlapped_io_
+                  ? InternalRecvFromOverlapped(buf, buf_len, address)
+                  : InternalRecvFromNonBlocking(buf, buf_len, address);
   if (nread != ERR_IO_PENDING)
     return nread;
 
   read_callback_ = callback;
   recv_from_address_ = address;
   return ERR_IO_PENDING;
 }
 
 int UDPSocketWin::Write(IOBuffer* buf,
                         int buf_len,
@@ skipping 12 matching lines @@
                                 int buf_len,
                                 const IPEndPoint* address,
                                 const CompletionCallback& callback) {
   DCHECK(CalledOnValidThread());
   DCHECK_NE(INVALID_SOCKET, socket_);
   CHECK(write_callback_.is_null());
   DCHECK(!callback.is_null());  // Synchronous operation not supported.
   DCHECK_GT(buf_len, 0);
   DCHECK(!send_to_address_.get());
 
-  int nwrite = InternalSendTo(buf, buf_len, address);
+  int nwrite = use_overlapped_io_
+                   ? InternalSendToOverlapped(buf, buf_len, address)
+                   : InternalSendToNonBlocking(buf, buf_len, address);
   if (nwrite != ERR_IO_PENDING)
     return nwrite;
 
   if (address)
     send_to_address_.reset(new IPEndPoint(*address));
   write_callback_ = callback;
   return ERR_IO_PENDING;
 }
 
 int UDPSocketWin::Connect(const IPEndPoint& address) {
@@ skipping 135 matching lines @@
 void UDPSocketWin::DoWriteCallback(int rv) {
   DCHECK_NE(rv, ERR_IO_PENDING);
   DCHECK(!write_callback_.is_null());
 
   // since Run may result in Write being called, clear write_callback_ up front.
   CompletionCallback c = write_callback_;
   write_callback_.Reset();
   c.Run(rv);
 }
 
-void UDPSocketWin::DidCompleteRead() {
+void UDPSocketWin::DidCompleteReadOverlapped() {
   DWORD num_bytes, flags;
-  BOOL ok = WSAGetOverlappedResult(socket_, &core_->read_overlapped_,
+  BOOL ok = WSAGetOverlappedResult(socket_, core_->read_overlapped(),
                                    &num_bytes, FALSE, &flags);
-  WSAResetEvent(core_->read_overlapped_.hEvent);
+  WSAResetEvent(core_->read_overlapped()->hEvent);
   int result = ok ? num_bytes : MapSystemError(WSAGetLastError());
   // Convert address.
   if (recv_from_address_ && result >= 0) {
     if (!ReceiveAddressToIPEndpoint(recv_from_address_))
       result = ERR_ADDRESS_INVALID;
   }
-  LogRead(result, core_->read_iobuffer_->data());
-  core_->read_iobuffer_ = NULL;
+  LogRead(result, core_->read_iobuffer()->data());
+  core_->set_read_iobuffer(NULL, 0);
   recv_from_address_ = NULL;
   DoReadCallback(result);
 }
 
+void UDPSocketWin::DidCompleteWriteOverlapped() {
+  DWORD num_bytes, flags;
+  BOOL ok = WSAGetOverlappedResult(socket_, core_->write_overlapped(),
+                                   &num_bytes, FALSE, &flags);
+  WSAResetEvent(core_->write_overlapped()->hEvent);
+  int result = ok ? num_bytes : MapSystemError(WSAGetLastError());
+  LogWrite(result, core_->write_iobuffer()->data(), send_to_address_.get());
+
+  send_to_address_.reset();
+  core_->set_write_iobuffer(NULL, 0);
+  DoWriteCallback(result);
+}
+
+void UDPSocketWin::OnReadSignaledNonBlocking() {
+  DCHECK(core_->read_iobuffer());
+  WSANETWORKEVENTS network_events;
+  int os_error = 0;
+  int rv = WSAEnumNetworkEvents(socket_, core_->read_event(), &network_events);
+  if (rv == SOCKET_ERROR) {
+    os_error = WSAGetLastError();
+    rv = MapSystemError(os_error);
+    DoReadCallback(rv);
+    return;
+  }
+  if (network_events.lNetworkEvents) {
+    DCHECK(network_events.lNetworkEvents & FD_READ);
+    // Regardless of the error code in network_events.iErrorCode[FD_READ_BIT]
+    // we will continue to call recvfrom because it gives a more accurate
+    // error code.
+    rv = InternalRecvFromNonBlocking(core_->read_iobuffer().get(),
+                                     core_->read_iobuffer_len(),
+                                     recv_from_address_);
+    if (rv == ERR_IO_PENDING)
+      return;
+  } else {
+    core_->WatchForRead();
+    return;
+  }
+  core_->set_read_iobuffer(NULL, 0);
+  recv_from_address_ = NULL;
+  DoReadCallback(rv);
+}
+
+void UDPSocketWin::OnWriteSignaledNonBlocking() {
+  DCHECK(core_->write_iobuffer());
+  WSANETWORKEVENTS network_events;
+  int os_error = 0;
+  int rv = WSAEnumNetworkEvents(socket_, core_->write_event(), &network_events);
+  if (rv == SOCKET_ERROR) {
+    os_error = WSAGetLastError();
+    rv = MapSystemError(os_error);
+    DoWriteCallback(rv);
+    return;
+  } else if (network_events.lNetworkEvents) {
+    DCHECK(network_events.lNetworkEvents & FD_WRITE);
+    // Regardless of the error code in network_events.iErrorCode[FD_WRITE_BIT]
+    // we will continue to call sendto because it gives a more accurate error
+    // code.
+    rv = InternalSendToNonBlocking(core_->write_iobuffer().get(),
+                                   core_->write_iobuffer_len(),
+                                   send_to_address_.get());
+    if (rv == ERR_IO_PENDING)
+      return;
+  } else {
+    core_->WatchForWrite();
+    return;
+  }
+  core_->set_write_iobuffer(NULL, 0);
+  send_to_address_.reset();
+  DoWriteCallback(rv);
+}
+
 void UDPSocketWin::LogRead(int result, const char* bytes) const {
   if (result < 0) {
     net_log_.AddEventWithNetErrorCode(NetLog::TYPE_UDP_RECEIVE_ERROR, result);
     return;
   }
 
   if (net_log_.IsLogging()) {
     // Get address for logging, if |address| is NULL.
     IPEndPoint address;
     bool is_address_valid = ReceiveAddressToIPEndpoint(&address);
     net_log_.AddEvent(
         NetLog::TYPE_UDP_BYTES_RECEIVED,
         CreateNetLogUDPDataTranferCallback(
             result, bytes,
             is_address_valid ? &address : NULL));
   }
 
   base::StatsCounter read_bytes("udp.read_bytes");
   read_bytes.Add(result);
   NetworkActivityMonitor::GetInstance()->IncrementBytesReceived(result);
 }
 
-void UDPSocketWin::DidCompleteWrite() {
-  DWORD num_bytes, flags;
-  BOOL ok = WSAGetOverlappedResult(socket_, &core_->write_overlapped_,
-                                   &num_bytes, FALSE, &flags);
-  WSAResetEvent(core_->write_overlapped_.hEvent);
-  int result = ok ? num_bytes : MapSystemError(WSAGetLastError());
-  LogWrite(result, core_->write_iobuffer_->data(), send_to_address_.get());
-
-  send_to_address_.reset();
-  core_->write_iobuffer_ = NULL;
-  DoWriteCallback(result);
-}
-
 void UDPSocketWin::LogWrite(int result,
                             const char* bytes,
                             const IPEndPoint* address) const {
   if (result < 0) {
     net_log_.AddEventWithNetErrorCode(NetLog::TYPE_UDP_SEND_ERROR, result);
     return;
   }
 
   if (net_log_.IsLogging()) {
     net_log_.AddEvent(
         NetLog::TYPE_UDP_BYTES_SENT,
         CreateNetLogUDPDataTranferCallback(result, bytes, address));
   }
 
   base::StatsCounter write_bytes("udp.write_bytes");
   write_bytes.Add(result);
   NetworkActivityMonitor::GetInstance()->IncrementBytesSent(result);
 }
 
-int UDPSocketWin::InternalRecvFrom(IOBuffer* buf, int buf_len,
-                                   IPEndPoint* address) {
-  DCHECK(!core_->read_iobuffer_.get());
-  SockaddrStorage& storage = core_->recv_addr_storage_;
-  storage.addr_len = sizeof(storage.addr_storage);
+int UDPSocketWin::InternalRecvFromOverlapped(IOBuffer* buf,
+                                             int buf_len,
+                                             IPEndPoint* address) {
+  DCHECK(!core_->read_iobuffer());
+  SockaddrStorage* storage = core_->recv_addr_storage();
+  storage->addr_len = sizeof(storage->addr_storage);
 
   WSABUF read_buffer;
   read_buffer.buf = buf->data();
   read_buffer.len = buf_len;
 
   DWORD flags = 0;
   DWORD num;
   CHECK_NE(INVALID_SOCKET, socket_);
-  AssertEventNotSignaled(core_->read_overlapped_.hEvent);
-  int rv = WSARecvFrom(socket_, &read_buffer, 1, &num, &flags, storage.addr,
-                       &storage.addr_len, &core_->read_overlapped_, NULL);
+  AssertEventNotSignaled(core_->read_overlapped()->hEvent);
+  int rv = WSARecvFrom(socket_, &read_buffer, 1, &num, &flags, storage->addr,
+                       &storage->addr_len, core_->read_overlapped(), NULL);
   if (rv == 0) {
-    if (ResetEventIfSignaled(core_->read_overlapped_.hEvent)) {
+    if (ResetEventIfSignaled(core_->read_overlapped()->hEvent)) {
       int result = num;
       // Convert address.
       if (address && result >= 0) {
         if (!ReceiveAddressToIPEndpoint(address))
           result = ERR_ADDRESS_INVALID;
       }
       LogRead(result, buf->data());
       return result;
     }
   } else {
     int os_error = WSAGetLastError();
     if (os_error != WSA_IO_PENDING) {
       int result = MapSystemError(os_error);
       LogRead(result, NULL);
       return result;
     }
   }
   core_->WatchForRead();
-  core_->read_iobuffer_ = buf;
+  core_->set_read_iobuffer(buf, buf_len);
   return ERR_IO_PENDING;
 }
 
-int UDPSocketWin::InternalSendTo(IOBuffer* buf, int buf_len,
-                                 const IPEndPoint* address) {
-  DCHECK(!core_->write_iobuffer_.get());
+int UDPSocketWin::InternalSendToOverlapped(IOBuffer* buf,
+                                           int buf_len,
+                                           const IPEndPoint* address) {
+  DCHECK(!core_->write_iobuffer());
   SockaddrStorage storage;
   struct sockaddr* addr = storage.addr;
   // Convert address.
   if (!address) {
     addr = NULL;
     storage.addr_len = 0;
   } else {
     if (!address->ToSockAddr(addr, &storage.addr_len)) {
       int result = ERR_ADDRESS_INVALID;
       LogWrite(result, NULL, NULL);
       return result;
     }
   }
 
   WSABUF write_buffer;
   write_buffer.buf = buf->data();
   write_buffer.len = buf_len;
 
   DWORD flags = 0;
   DWORD num;
-  AssertEventNotSignaled(core_->write_overlapped_.hEvent);
-  int rv = WSASendTo(socket_, &write_buffer, 1, &num, flags,
-                     addr, storage.addr_len, &core_->write_overlapped_, NULL);
+  AssertEventNotSignaled(core_->write_overlapped()->hEvent);
+  int rv = WSASendTo(socket_, &write_buffer, 1, &num, flags, addr,
+                     storage.addr_len, core_->write_overlapped(), NULL);
   if (rv == 0) {
-    if (ResetEventIfSignaled(core_->write_overlapped_.hEvent)) {
+    if (ResetEventIfSignaled(core_->write_overlapped()->hEvent)) {
       int result = num;
       LogWrite(result, buf->data(), address);
       return result;
     }
   } else {
     int os_error = WSAGetLastError();
     if (os_error != WSA_IO_PENDING) {
       int result = MapSystemError(os_error);
       LogWrite(result, NULL, NULL);
       return result;
     }
   }
 
   core_->WatchForWrite();
-  core_->write_iobuffer_ = buf;
+  core_->set_write_iobuffer(buf, 0);
   return ERR_IO_PENDING;
 }
 
+int UDPSocketWin::InternalRecvFromNonBlocking(IOBuffer* buf,
+                                              int buf_len,
+                                              IPEndPoint* address) {
+  if (!non_blocking_reads_initialized_) {
+    // After this call the event will be signaled when asynchronous read is
+    // completed.g
+    WSAEventSelect(socket_, core_->read_event(), FD_READ);
+    non_blocking_reads_initialized_ = true;
+  }
+  SockaddrStorage* storage = core_->recv_addr_storage();
+  storage->addr_len = sizeof(storage->addr_storage);
+
+  CHECK_NE(INVALID_SOCKET, socket_);
+  int rv = recvfrom(socket_, buf->data(), buf_len, 0, storage->addr,
+                    &storage->addr_len);
+  if (rv == SOCKET_ERROR) {
+    int os_error = WSAGetLastError();
+    if (os_error == WSAEWOULDBLOCK) {
+      core_->WatchForRead();
+      core_->set_read_iobuffer(buf, buf_len);
+      return ERR_IO_PENDING;
+    } else {
+      rv = MapSystemError(os_error);
+      LogRead(rv, NULL);
+      return rv;
+    }
+  } else {
+    // Convert address.
+    if (address && rv >= 0 && !ReceiveAddressToIPEndpoint(address)) {
+      rv = ERR_ADDRESS_INVALID;
+    }
+    LogRead(rv, buf->data());
+    return rv;
+  }
+}
+
+int UDPSocketWin::InternalSendToNonBlocking(IOBuffer* buf,
+                                            int buf_len,
+                                            const IPEndPoint* address) {
+  if (!non_blocking_writes_initialized_) {
+    // After this call the event will be signaled when asynchronous write is
+    // completed.
+    WSAEventSelect(socket_, core_->write_event(), FD_WRITE);
+    non_blocking_writes_initialized_ = true;
+  }
+  SockaddrStorage storage;
+  struct sockaddr* addr = storage.addr;
+  // Convert address.
+  if (address) {
+    if (!address->ToSockAddr(addr, &storage.addr_len)) {
+      int result = ERR_ADDRESS_INVALID;
+      LogWrite(result, NULL, NULL);
+      return result;
+    }
+  } else {
+    addr = NULL;
+    storage.addr_len = 0;
+  }
+
+  int rv = sendto(socket_, buf->data(), buf_len, 0, addr, storage.addr_len);
+  if (rv == SOCKET_ERROR) {
+    int os_error = WSAGetLastError();
+    if (os_error == WSAEWOULDBLOCK) {
+      core_->WatchForWrite();
+      core_->set_write_iobuffer(buf, buf_len);
+      return ERR_IO_PENDING;
+    } else {
+      rv = MapSystemError(os_error);
+      LogWrite(rv, NULL, NULL);
+      return rv;
+    }
+  } else {
+    LogWrite(rv, buf->data(), address);
+    return rv;
+  }
+}
+
 int UDPSocketWin::SetMulticastOptions() {
   if (!(socket_options_ & SOCKET_OPTION_MULTICAST_LOOP)) {
     DWORD loop = 0;
     int protocol_level =
         addr_family_ == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
     int option =
         addr_family_ == AF_INET ? IP_MULTICAST_LOOP: IPV6_MULTICAST_LOOP;
     int rv = setsockopt(socket_, protocol_level, option,
                         reinterpret_cast<const char*>(&loop), sizeof(loop));
     if (rv < 0)
@@ skipping 65 matching lines @@
   for (int i = 0; i < kBindRetries; ++i) {
     int rv = DoBind(IPEndPoint(
         address, static_cast<uint16>(rand_int_cb_.Run(kPortStart, kPortEnd))));
     if (rv == OK || rv != ERR_ADDRESS_IN_USE)
       return rv;
   }
   return DoBind(IPEndPoint(address, 0));
 }
 
 bool UDPSocketWin::ReceiveAddressToIPEndpoint(IPEndPoint* address) const {
-  SockaddrStorage& storage = core_->recv_addr_storage_;
-  return address->FromSockAddr(storage.addr, storage.addr_len);
+  SockaddrStorage* storage = core_->recv_addr_storage();
+  return address->FromSockAddr(storage->addr, storage->addr_len);
 }
 
 int UDPSocketWin::JoinGroup(
     const IPAddressNumber& group_address) const {
   DCHECK(CalledOnValidThread());
   if (!is_connected())
     return ERR_SOCKET_NOT_CONNECTED;
 
   switch (group_address.size()) {
     case kIPv4AddressSize: {
@@ skipping 186 matching lines @@
               0,
               NULL);
 
   return OK;
 }
 
 void UDPSocketWin::DetachFromThread() {
   base::NonThreadSafe::DetachFromThread();
 }
 
+void UDPSocketWin::UseNonBlockingIO() {
+  if (core_) {
+    NOTREACHED() << "Cannot change to non-blocking mode after socket is used.";
+  } else {
+    use_overlapped_io_ = false;
+  }
+}
+
 }  // namespace net