// 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/callback.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/message_loop/message_loop.h"
#include "base/metrics/histogram.h"
#include "base/metrics/sparse_histogram.h"
#include "base/metrics/stats_counters.h"
#include "base/profiler/scoped_tracker.h"
#include "base/rand_util.h"
#include "net/base/io_buffer.h"
#include "net/base/ip_endpoint.h"
#include "net/base/net_errors.h"
#include "net/base/net_log.h"
#include "net/base/net_util.h"
#include "net/base/winsock_init.h"
#include "net/base/winsock_util.h"
#include "net/socket/socket_descriptor.h"
#include "net/udp/udp_net_log_parameters.h"

namespace {

const int kBindRetries = 10;
const int kPortStart = 1024;
const int kPortEnd = 65535;

}  // namespace

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);

  // Start watching for the end of a read or write operation.
  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_;

  // The buffers used in Read() and Write().
  scoped_refptr<IOBuffer> read_iobuffer_;
  scoped_refptr<IOBuffer> write_iobuffer_;

  // The address storage passed to WSARecvFrom().
  SockaddrStorage 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:
    virtual void OnObjectSignaled(HANDLE object);

   private:
    Core* const core_;
  };

  class WriteDelegate : public base::win::ObjectWatcher::Delegate {
   public:
    explicit WriteDelegate(Core* core) : core_(core) {}
    virtual ~WriteDelegate() {}

    // base::ObjectWatcher::Delegate methods:
    virtual void OnObjectSignaled(HANDLE object);

   private:
    Core* const core_;
  };

  ~Core();

  // The socket that created this object.
  UDPSocketWin* socket_;

  // |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_;

  DISALLOW_COPY_AND_ASSIGN(Core);
};

UDPSocketWin::Core::Core(UDPSocketWin* socket)
    : socket_(socket),
      reader_(this),
      writer_(this) {
  memset(&read_overlapped_, 0, sizeof(read_overlapped_));
  memset(&write_overlapped_, 0, sizeof(write_overlapped_));

  read_overlapped_.hEvent = WSACreateEvent();
  write_overlapped_.hEvent = 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_));
}

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_);
}

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_);
}

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();

  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();

  core_->Release();
}
//-----------------------------------------------------------------------------

QwaveAPI::QwaveAPI() : qwave_supported_(false) {
  HMODULE qwave = LoadLibrary(L"qwave.dll");
  if (!qwave)
    return;
  create_handle_func_ =
      (CreateHandleFn)GetProcAddress(qwave, "QOSCreateHandle");
  close_handle_func_ =
      (CloseHandleFn)GetProcAddress(qwave, "QOSCloseHandle");
  add_socket_to_flow_func_ =
      (AddSocketToFlowFn)GetProcAddress(qwave, "QOSAddSocketToFlow");
  remove_socket_from_flow_func_ =
      (RemoveSocketFromFlowFn)GetProcAddress(qwave, "QOSRemoveSocketFromFlow");
  set_flow_func_ = (SetFlowFn)GetProcAddress(qwave, "QOSSetFlow");

  if (create_handle_func_ && close_handle_func_ &&
      add_socket_to_flow_func_ && remove_socket_from_flow_func_ &&
      set_flow_func_) {
    qwave_supported_ = true;
  }
}

QwaveAPI& QwaveAPI::Get() {
  static base::LazyInstance<QwaveAPI>::Leaky lazy_qwave =
    LAZY_INSTANCE_INITIALIZER;
  return lazy_qwave.Get();
}

bool QwaveAPI::qwave_supported() const {
  return qwave_supported_;
}
BOOL QwaveAPI::CreateHandle(PQOS_VERSION version, PHANDLE handle) {
  return create_handle_func_(version, handle);
}
BOOL QwaveAPI::CloseHandle(HANDLE handle) {
  return close_handle_func_(handle);
}

BOOL QwaveAPI::AddSocketToFlow(HANDLE handle,
                               SOCKET socket,
                               PSOCKADDR addr,
                               QOS_TRAFFIC_TYPE traffic_type,
                               DWORD flags,
                               PQOS_FLOWID flow_id) {
  return add_socket_to_flow_func_(handle,
                                  socket,
                                  addr,
                                  traffic_type,
                                  flags,
                                  flow_id);
}

BOOL QwaveAPI::RemoveSocketFromFlow(HANDLE handle,
                                    SOCKET socket,
                                    QOS_FLOWID flow_id,
                                    DWORD reserved) {
  return remove_socket_from_flow_func_(handle, socket, flow_id, reserved);
}

BOOL QwaveAPI::SetFlow(HANDLE handle,
                       QOS_FLOWID flow_id,
                       QOS_SET_FLOW op,
                       ULONG size,
                       PVOID data,
                       DWORD reserved,
                       LPOVERLAPPED overlapped) {
  return set_flow_func_(handle,
                        flow_id,
                        op,
                        size,
                        data,
                        reserved,
                        overlapped);
}


//-----------------------------------------------------------------------------

UDPSocketWin::UDPSocketWin(DatagramSocket::BindType bind_type,
                           const RandIntCallback& rand_int_cb,
                           net::NetLog* net_log,
                           const net::NetLog::Source& source)
    : socket_(INVALID_SOCKET),
      addr_family_(0),
      socket_options_(SOCKET_OPTION_MULTICAST_LOOP),
      multicast_interface_(0),
      multicast_time_to_live_(1),
      bind_type_(bind_type),
      rand_int_cb_(rand_int_cb),
      recv_from_address_(NULL),
      net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_UDP_SOCKET)),
      qos_handle_(NULL),
      qos_flow_id_(0) {
  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);
}

void UDPSocketWin::Close() {
  DCHECK(CalledOnValidThread());

  if (!is_connected())
    return;

  if (qos_handle_) {
    QwaveAPI::Get().CloseHandle(qos_handle_);
  }

  // Zero out any pending read/write callback state.
  read_callback_.Reset();
  recv_from_address_ = NULL;
  write_callback_.Reset();

  base::TimeTicks start_time = base::TimeTicks::Now();
  closesocket(socket_);
  UMA_HISTOGRAM_TIMES("Net.UDPSocketWinClose",
                      base::TimeTicks::Now() - start_time);
  socket_ = INVALID_SOCKET;
  addr_family_ = 0;

  core_->Detach();
  core_ = NULL;
}

int UDPSocketWin::GetPeerAddress(IPEndPoint* address) const {
  DCHECK(CalledOnValidThread());
  DCHECK(address);
  if (!is_connected())
    return ERR_SOCKET_NOT_CONNECTED;

  // TODO(szym): Simplify. http://crbug.com/126152
  if (!remote_address_.get()) {
    SockaddrStorage storage;
    if (getpeername(socket_, storage.addr, &storage.addr_len))
      return MapSystemError(WSAGetLastError());
    scoped_ptr<IPEndPoint> address(new IPEndPoint());
    if (!address->FromSockAddr(storage.addr, storage.addr_len))
      return ERR_ADDRESS_INVALID;
    remote_address_.reset(address.release());
  }

  *address = *remote_address_;
  return OK;
}

int UDPSocketWin::GetLocalAddress(IPEndPoint* address) const {
  DCHECK(CalledOnValidThread());
  DCHECK(address);
  if (!is_connected())
    return ERR_SOCKET_NOT_CONNECTED;

  // TODO(szym): Simplify. http://crbug.com/126152
  if (!local_address_.get()) {
    SockaddrStorage storage;
    if (getsockname(socket_, storage.addr, &storage.addr_len))
      return MapSystemError(WSAGetLastError());
    scoped_ptr<IPEndPoint> address(new IPEndPoint());
    if (!address->FromSockAddr(storage.addr, storage.addr_len))
      return ERR_ADDRESS_INVALID;
    local_address_.reset(address.release());
    net_log_.AddEvent(NetLog::TYPE_UDP_LOCAL_ADDRESS,
                      CreateNetLogUDPConnectCallback(local_address_.get()));
  }

  *address = *local_address_;
  return OK;
}

int UDPSocketWin::Read(IOBuffer* buf,
                       int buf_len,
                       const CompletionCallback& callback) {
  return RecvFrom(buf, buf_len, NULL, callback);
}

int UDPSocketWin::RecvFrom(IOBuffer* buf,
                           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);
  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,
                        const CompletionCallback& callback) {
  return SendToOrWrite(buf, buf_len, NULL, callback);
}

int UDPSocketWin::SendTo(IOBuffer* buf,
                         int buf_len,
                         const IPEndPoint& address,
                         const CompletionCallback& callback) {
  return SendToOrWrite(buf, buf_len, &address, callback);
}

int UDPSocketWin::SendToOrWrite(IOBuffer* buf,
                                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);
  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) {
  net_log_.BeginEvent(NetLog::TYPE_UDP_CONNECT,
                      CreateNetLogUDPConnectCallback(&address));
  int rv = InternalConnect(address);
  if (rv != OK)
    Close();
  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_UDP_CONNECT, rv);
  return rv;
}

int UDPSocketWin::InternalConnect(const IPEndPoint& address) {
  DCHECK(!is_connected());
  DCHECK(!remote_address_.get());
  int addr_family = address.GetSockAddrFamily();
  int rv = CreateSocket(addr_family);
  if (rv < 0)
    return rv;

  if (bind_type_ == DatagramSocket::RANDOM_BIND) {
    // Construct IPAddressNumber of appropriate size (IPv4 or IPv6) of 0s,
    // representing INADDR_ANY or in6addr_any.
    size_t addr_size =
        addr_family == AF_INET ? kIPv4AddressSize : kIPv6AddressSize;
    IPAddressNumber addr_any(addr_size);
    rv = RandomBind(addr_any);
  }
  // else connect() does the DatagramSocket::DEFAULT_BIND

  if (rv < 0) {
    UMA_HISTOGRAM_SPARSE_SLOWLY("Net.UdpSocketRandomBindErrorCode", -rv);
    Close();
    return rv;
  }

  SockaddrStorage storage;
  if (!address.ToSockAddr(storage.addr, &storage.addr_len))
    return ERR_ADDRESS_INVALID;

  rv = connect(socket_, storage.addr, storage.addr_len);
  if (rv < 0) {
    // Close() may change the last error. Map it beforehand.
    int result = MapSystemError(WSAGetLastError());
    Close();
    return result;
  }

  remote_address_.reset(new IPEndPoint(address));
  return rv;
}

int UDPSocketWin::Bind(const IPEndPoint& address) {
  DCHECK(!is_connected());
  int rv = CreateSocket(address.GetSockAddrFamily());
  if (rv < 0)
    return rv;
  rv = SetSocketOptions();
  if (rv < 0) {
    Close();
    return rv;
  }
  rv = DoBind(address);
  if (rv < 0) {
    Close();
    return rv;
  }
  local_address_.reset();
  return rv;
}

int UDPSocketWin::CreateSocket(int addr_family) {
  addr_family_ = addr_family;
  socket_ = CreatePlatformSocket(addr_family_, SOCK_DGRAM, IPPROTO_UDP);
  if (socket_ == INVALID_SOCKET)
    return MapSystemError(WSAGetLastError());
  core_ = new Core(this);
  return OK;
}

int UDPSocketWin::SetReceiveBufferSize(int32 size) {
  DCHECK(CalledOnValidThread());
  int rv = setsockopt(socket_, SOL_SOCKET, SO_RCVBUF,
                      reinterpret_cast<const char*>(&size), sizeof(size));
  if (rv != 0)
    return MapSystemError(WSAGetLastError());

  // According to documentation, setsockopt may succeed, but we need to check
  // the results via getsockopt to be sure it works on Windows.
  int32 actual_size = 0;
  int option_size = sizeof(actual_size);
  rv = getsockopt(socket_, SOL_SOCKET, SO_RCVBUF,
                  reinterpret_cast<char*>(&actual_size), &option_size);
  if (rv != 0)
    return MapSystemError(WSAGetLastError());
  if (actual_size >= size)
    return OK;
  UMA_HISTOGRAM_CUSTOM_COUNTS("Net.SocketUnchangeableReceiveBuffer",
                              actual_size, 1000, 1000000, 50);
  return ERR_SOCKET_RECEIVE_BUFFER_SIZE_UNCHANGEABLE;
}

int UDPSocketWin::SetSendBufferSize(int32 size) {
  DCHECK(CalledOnValidThread());
  int rv = setsockopt(socket_, SOL_SOCKET, SO_SNDBUF,
                      reinterpret_cast<const char*>(&size), sizeof(size));
  if (rv != 0)
    return MapSystemError(WSAGetLastError());
  // According to documentation, setsockopt may succeed, but we need to check
  // the results via getsockopt to be sure it works on Windows.
  int32 actual_size = 0;
  int option_size = sizeof(actual_size);
  rv = getsockopt(socket_, SOL_SOCKET, SO_SNDBUF,
                  reinterpret_cast<char*>(&actual_size), &option_size);
  if (rv != 0)
    return MapSystemError(WSAGetLastError());
  if (actual_size >= size)
    return OK;
  UMA_HISTOGRAM_CUSTOM_COUNTS("Net.SocketUnchangeableSendBuffer",
                              actual_size, 1000, 1000000, 50);
  return ERR_SOCKET_SEND_BUFFER_SIZE_UNCHANGEABLE;
}

void UDPSocketWin::AllowAddressReuse() {
  DCHECK(CalledOnValidThread());
  DCHECK(!is_connected());

  socket_options_ |= SOCKET_OPTION_REUSE_ADDRESS;
}

void UDPSocketWin::AllowBroadcast() {
  DCHECK(CalledOnValidThread());
  DCHECK(!is_connected());

  socket_options_ |= SOCKET_OPTION_BROADCAST;
}

void UDPSocketWin::DoReadCallback(int rv) {
  DCHECK_NE(rv, ERR_IO_PENDING);
  DCHECK(!read_callback_.is_null());

  // since Run may result in Read being called, clear read_callback_ up front.
  CompletionCallback c = read_callback_;
  read_callback_.Reset();
  c.Run(rv);
}

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() {
  DWORD num_bytes, flags;
  BOOL ok = WSAGetOverlappedResult(socket_, &core_->read_overlapped_,
                                   &num_bytes, FALSE, &flags);
  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;
  recv_from_address_ = NULL;
  DoReadCallback(result);
}

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);
}

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);
}

int UDPSocketWin::InternalRecvFrom(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);
  if (rv == 0) {
    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;
  return ERR_IO_PENDING;
}

int UDPSocketWin::InternalSendTo(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);
  if (rv == 0) {
    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;
  return ERR_IO_PENDING;
}

int UDPSocketWin::SetSocketOptions() {
  BOOL true_value = 1;
  if (socket_options_ & SOCKET_OPTION_REUSE_ADDRESS) {
    int rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR,
                        reinterpret_cast<const char*>(&true_value),
                        sizeof(true_value));
    if (rv < 0)
      return MapSystemError(WSAGetLastError());
  }
  if (socket_options_ & SOCKET_OPTION_BROADCAST) {
    int rv = setsockopt(socket_, SOL_SOCKET, SO_BROADCAST,
                        reinterpret_cast<const char*>(&true_value),
                        sizeof(true_value));
    if (rv < 0)
      return MapSystemError(WSAGetLastError());
  }
  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)
      return MapSystemError(WSAGetLastError());
  }
  if (multicast_time_to_live_ != 1) {
    DWORD hops = multicast_time_to_live_;
    int protocol_level =
        addr_family_ == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
    int option =
        addr_family_ == AF_INET ? IP_MULTICAST_TTL: IPV6_MULTICAST_HOPS;
    int rv = setsockopt(socket_, protocol_level, option,
                        reinterpret_cast<const char*>(&hops), sizeof(hops));
    if (rv < 0)
      return MapSystemError(WSAGetLastError());
  }
  if (multicast_interface_ != 0) {
    switch (addr_family_) {
      case AF_INET: {
        in_addr address;
        address.s_addr = htonl(multicast_interface_);
        int rv = setsockopt(socket_, IPPROTO_IP, IP_MULTICAST_IF,
                            reinterpret_cast<const char*>(&address),
                            sizeof(address));
        if (rv)
          return MapSystemError(WSAGetLastError());
        break;
      }
      case AF_INET6: {
        uint32 interface_index = multicast_interface_;
        int rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_MULTICAST_IF,
                            reinterpret_cast<const char*>(&interface_index),
                            sizeof(interface_index));
        if (rv)
          return MapSystemError(WSAGetLastError());
        break;
      }
      default:
        NOTREACHED() << "Invalid address family";
        return ERR_ADDRESS_INVALID;
    }
  }
  return OK;
}

int UDPSocketWin::DoBind(const IPEndPoint& address) {
  SockaddrStorage storage;
  if (!address.ToSockAddr(storage.addr, &storage.addr_len))
    return ERR_ADDRESS_INVALID;
  int rv = bind(socket_, storage.addr, storage.addr_len);
  if (rv == 0)
    return OK;
  int last_error = WSAGetLastError();
  UMA_HISTOGRAM_SPARSE_SLOWLY("Net.UdpSocketBindErrorFromWinOS", last_error);
  // Map some codes that are special to bind() separately.
  // * WSAEACCES: If a port is already bound to a socket, WSAEACCES may be
  //   returned instead of WSAEADDRINUSE, depending on whether the socket
  //   option SO_REUSEADDR or SO_EXCLUSIVEADDRUSE is set and whether the
  //   conflicting socket is owned by a different user account. See the MSDN
  //   page "Using SO_REUSEADDR and SO_EXCLUSIVEADDRUSE" for the gory details.
  if (last_error == WSAEACCES || last_error == WSAEADDRNOTAVAIL)
    return ERR_ADDRESS_IN_USE;
  return MapSystemError(last_error);
}

int UDPSocketWin::RandomBind(const IPAddressNumber& address) {
  DCHECK(bind_type_ == DatagramSocket::RANDOM_BIND && !rand_int_cb_.is_null());

  for (int i = 0; i < kBindRetries; ++i) {
    int rv = DoBind(IPEndPoint(address,
                               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);
}

int UDPSocketWin::JoinGroup(
    const IPAddressNumber& group_address) const {
  DCHECK(CalledOnValidThread());
  if (!is_connected())
    return ERR_SOCKET_NOT_CONNECTED;

  switch (group_address.size()) {
    case kIPv4AddressSize: {
      if (addr_family_ != AF_INET)
        return ERR_ADDRESS_INVALID;
      ip_mreq mreq;
      mreq.imr_interface.s_addr = htonl(multicast_interface_);
      memcpy(&mreq.imr_multiaddr, &group_address[0], kIPv4AddressSize);
      int rv = setsockopt(socket_, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                          reinterpret_cast<const char*>(&mreq),
                          sizeof(mreq));
      if (rv)
        return MapSystemError(WSAGetLastError());
      return OK;
    }
    case kIPv6AddressSize: {
      if (addr_family_ != AF_INET6)
        return ERR_ADDRESS_INVALID;
      ipv6_mreq mreq;
      mreq.ipv6mr_interface = multicast_interface_;
      memcpy(&mreq.ipv6mr_multiaddr, &group_address[0], kIPv6AddressSize);
      int rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
                          reinterpret_cast<const char*>(&mreq),
                          sizeof(mreq));
      if (rv)
        return MapSystemError(WSAGetLastError());
      return OK;
    }
    default:
      NOTREACHED() << "Invalid address family";
      return ERR_ADDRESS_INVALID;
  }
}

int UDPSocketWin::LeaveGroup(
    const IPAddressNumber& group_address) const {
  DCHECK(CalledOnValidThread());
  if (!is_connected())
    return ERR_SOCKET_NOT_CONNECTED;

  switch (group_address.size()) {
    case kIPv4AddressSize: {
      if (addr_family_ != AF_INET)
        return ERR_ADDRESS_INVALID;
      ip_mreq mreq;
      mreq.imr_interface.s_addr = htonl(multicast_interface_);
      memcpy(&mreq.imr_multiaddr, &group_address[0], kIPv4AddressSize);
      int rv = setsockopt(socket_, IPPROTO_IP, IP_DROP_MEMBERSHIP,
                          reinterpret_cast<const char*>(&mreq), sizeof(mreq));
      if (rv)
        return MapSystemError(WSAGetLastError());
      return OK;
    }
    case kIPv6AddressSize: {
      if (addr_family_ != AF_INET6)
        return ERR_ADDRESS_INVALID;
      ipv6_mreq mreq;
      mreq.ipv6mr_interface = multicast_interface_;
      memcpy(&mreq.ipv6mr_multiaddr, &group_address[0], kIPv6AddressSize);
      int rv = setsockopt(socket_, IPPROTO_IPV6, IP_DROP_MEMBERSHIP,
                          reinterpret_cast<const char*>(&mreq), sizeof(mreq));
      if (rv)
        return MapSystemError(WSAGetLastError());
      return OK;
    }
    default:
      NOTREACHED() << "Invalid address family";
      return ERR_ADDRESS_INVALID;
  }
}

int UDPSocketWin::SetMulticastInterface(uint32 interface_index) {
  DCHECK(CalledOnValidThread());
  if (is_connected())
    return ERR_SOCKET_IS_CONNECTED;
  multicast_interface_ = interface_index;
  return OK;
}

int UDPSocketWin::SetMulticastTimeToLive(int time_to_live) {
  DCHECK(CalledOnValidThread());
  if (is_connected())
    return ERR_SOCKET_IS_CONNECTED;

  if (time_to_live < 0 || time_to_live > 255)
    return ERR_INVALID_ARGUMENT;
  multicast_time_to_live_ = time_to_live;
  return OK;
}

int UDPSocketWin::SetMulticastLoopbackMode(bool loopback) {
  DCHECK(CalledOnValidThread());
  if (is_connected())
    return ERR_SOCKET_IS_CONNECTED;

  if (loopback)
    socket_options_ |= SOCKET_OPTION_MULTICAST_LOOP;
  else
    socket_options_ &= ~SOCKET_OPTION_MULTICAST_LOOP;
  return OK;
}

int UDPSocketWin::SetDiffServCodePoint(DiffServCodePoint dscp) {
  if (dscp == DSCP_NO_CHANGE) {
    return OK;
  }

  if (!is_connected())
    return ERR_SOCKET_NOT_CONNECTED;

  QwaveAPI& qos(QwaveAPI::Get());

  if (!qos.qwave_supported())
    return ERROR_NOT_SUPPORTED;

  if (qos_handle_ == NULL) {
    QOS_VERSION version;
    version.MajorVersion = 1;
    version.MinorVersion = 0;
    qos.CreateHandle(&version, &qos_handle_);
    if (qos_handle_ == NULL)
      return ERROR_NOT_SUPPORTED;
  }

  QOS_TRAFFIC_TYPE traffic_type = QOSTrafficTypeBestEffort;
  switch (dscp) {
    case DSCP_CS0:
      traffic_type = QOSTrafficTypeBestEffort;
      break;
    case DSCP_CS1:
      traffic_type = QOSTrafficTypeBackground;
      break;
    case DSCP_AF11:
    case DSCP_AF12:
    case DSCP_AF13:
    case DSCP_CS2:
    case DSCP_AF21:
    case DSCP_AF22:
    case DSCP_AF23:
    case DSCP_CS3:
    case DSCP_AF31:
    case DSCP_AF32:
    case DSCP_AF33:
    case DSCP_CS4:
      traffic_type = QOSTrafficTypeExcellentEffort;
      break;
    case DSCP_AF41:
    case DSCP_AF42:
    case DSCP_AF43:
    case DSCP_CS5:
      traffic_type = QOSTrafficTypeAudioVideo;
      break;
    case DSCP_EF:
    case DSCP_CS6:
      traffic_type = QOSTrafficTypeVoice;
      break;
    case DSCP_CS7:
      traffic_type = QOSTrafficTypeControl;
      break;
    case DSCP_NO_CHANGE:
      NOTREACHED();
      break;
  }
  if (qos_flow_id_ != 0) {
    qos.RemoveSocketFromFlow(qos_handle_, NULL, qos_flow_id_, 0);
    qos_flow_id_ = 0;
  }
  if (!qos.AddSocketToFlow(qos_handle_,
                           socket_,
                           NULL,
                           traffic_type,
                           QOS_NON_ADAPTIVE_FLOW,
                           &qos_flow_id_)) {
    DWORD err = GetLastError();
    if (err == ERROR_DEVICE_REINITIALIZATION_NEEDED) {
      qos.CloseHandle(qos_handle_);
      qos_flow_id_ = 0;
      qos_handle_ = 0;
    }
    return MapSystemError(err);
  }
  // This requires admin rights, and may fail, if so we ignore it
  // as AddSocketToFlow should still do *approximately* the right thing.
  DWORD buf = dscp;
  qos.SetFlow(qos_handle_,
              qos_flow_id_,
              QOSSetOutgoingDSCPValue,
              sizeof(buf),
              &buf,
              0,
              NULL);

  return OK;
}

void UDPSocketWin::DetachFromThread() {
  base::NonThreadSafe::DetachFromThread();
}

}  // namespace net