//
// detail/impl/socket_ops.ipp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2011 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BOOST_ASIO_DETAIL_SOCKET_OPS_IPP
#define BOOST_ASIO_DETAIL_SOCKET_OPS_IPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include <boost/asio/detail/config.hpp>
#include <boost/assert.hpp>
#include <boost/detail/workaround.hpp>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cerrno>
#include <new>
#include <boost/asio/detail/socket_ops.hpp>
#include <boost/asio/error.hpp>

#include <boost/asio/detail/push_options.hpp>

namespace boost {
namespace asio {
namespace detail {
namespace socket_ops {

#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
struct msghdr { int msg_namelen; };
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)

#if defined(__hpux)
// HP-UX doesn't declare these functions extern "C", so they are declared again
// here to avoid linker errors about undefined symbols.
extern "C" char* if_indextoname(unsigned int, char*);
extern "C" unsigned int if_nametoindex(const char*);
#endif // defined(__hpux)

inline void clear_last_error()
{
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  WSASetLastError(0);
#else
  errno = 0;
#endif
}

template <typename ReturnType>
inline ReturnType error_wrapper(ReturnType return_value,
    boost::system::error_code& ec)
{
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  ec = boost::system::error_code(WSAGetLastError(),
      boost::asio::error::get_system_category());
#else
  ec = boost::system::error_code(errno,
      boost::asio::error::get_system_category());
#endif
  return return_value;
}

template <typename SockLenType>
inline socket_type call_accept(SockLenType msghdr::*,
    socket_type s, socket_addr_type* addr, std::size_t* addrlen)
{
  SockLenType tmp_addrlen = addrlen ? (SockLenType)*addrlen : 0;
  socket_type result = ::accept(s, addr, addrlen ? &tmp_addrlen : 0);
  if (addrlen)
    *addrlen = (std::size_t)tmp_addrlen;
  return result;
}

socket_type accept(socket_type s, socket_addr_type* addr,
    std::size_t* addrlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return invalid_socket;
  }

  clear_last_error();

  socket_type new_s = error_wrapper(call_accept(
        &msghdr::msg_namelen, s, addr, addrlen), ec);
  if (new_s == invalid_socket)
    return new_s;

#if defined(__MACH__) && defined(__APPLE__) || defined(__FreeBSD__)
  int optval = 1;
  int result = error_wrapper(::setsockopt(new_s,
        SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval)), ec);
  if (result != 0)
  {
    ::close(new_s);
    return invalid_socket;
  }
#endif

  ec = boost::system::error_code();
  return new_s;
}

socket_type sync_accept(socket_type s, state_type state,
    socket_addr_type* addr, std::size_t* addrlen, boost::system::error_code& ec)
{
  // Accept a socket.
  for (;;)
  {
    // Try to complete the operation without blocking.
    socket_type new_socket = socket_ops::accept(s, addr, addrlen, ec);

    // Check if operation succeeded.
    if (new_socket != invalid_socket)
      return new_socket;

    // Operation failed.
    if (ec == boost::asio::error::would_block
        || ec == boost::asio::error::try_again)
    {
      if (state & user_set_non_blocking)
        return invalid_socket;
      // Fall through to retry operation.
    }
    else if (ec == boost::asio::error::connection_aborted)
    {
      if (state & enable_connection_aborted)
        return invalid_socket;
      // Fall through to retry operation.
    }
#if defined(EPROTO)
    else if (ec.value() == EPROTO)
    {
      if (state & enable_connection_aborted)
        return invalid_socket;
      // Fall through to retry operation.
    }
#endif // defined(EPROTO)
    else
      return invalid_socket;

    // Wait for socket to become ready.
    if (socket_ops::poll_read(s, ec) < 0)
      return invalid_socket;
  }
}

#if defined(BOOST_ASIO_HAS_IOCP)

void complete_iocp_accept(socket_type s,
    void* output_buffer, DWORD address_length,
    socket_addr_type* addr, std::size_t* addrlen,
    socket_type new_socket, boost::system::error_code& ec)
{
  // Map non-portable errors to their portable counterparts.
  if (ec.value() == ERROR_NETNAME_DELETED)
    ec = boost::asio::error::connection_aborted;

  if (!ec)
  {
    // Get the address of the peer.
    if (addr && addrlen)
    {
      LPSOCKADDR local_addr = 0;
      int local_addr_length = 0;
      LPSOCKADDR remote_addr = 0;
      int remote_addr_length = 0;
      GetAcceptExSockaddrs(output_buffer, 0, address_length,
          address_length, &local_addr, &local_addr_length,
          &remote_addr, &remote_addr_length);
      if (static_cast<std::size_t>(remote_addr_length) > *addrlen)
      {
        ec = boost::asio::error::invalid_argument;
      }
      else
      {
        using namespace std; // For memcpy.
        memcpy(addr, remote_addr, remote_addr_length);
        *addrlen = static_cast<std::size_t>(remote_addr_length);
      }
    }

    // Need to set the SO_UPDATE_ACCEPT_CONTEXT option so that getsockname
    // and getpeername will work on the accepted socket.
    SOCKET update_ctx_param = s;
    socket_ops::state_type state = 0;
    socket_ops::setsockopt(new_socket, state,
          SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT,
          &update_ctx_param, sizeof(SOCKET), ec);
  }
}

#else // defined(BOOST_ASIO_HAS_IOCP)

bool non_blocking_accept(socket_type s,
    state_type state, socket_addr_type* addr, std::size_t* addrlen,
    boost::system::error_code& ec, socket_type& new_socket)
{
  for (;;)
  {
    // Accept the waiting connection.
    new_socket = socket_ops::accept(s, addr, addrlen, ec);

    // Check if operation succeeded.
    if (new_socket != invalid_socket)
      return true;

    // Retry operation if interrupted by signal.
    if (ec == boost::asio::error::interrupted)
      continue;

    // Operation failed.
    if (ec == boost::asio::error::would_block
        || ec == boost::asio::error::try_again)
    {
      if (state & user_set_non_blocking)
        return true;
      // Fall through to retry operation.
    }
    else if (ec == boost::asio::error::connection_aborted)
    {
      if (state & enable_connection_aborted)
        return true;
      // Fall through to retry operation.
    }
#if defined(EPROTO)
    else if (ec.value() == EPROTO)
    {
      if (state & enable_connection_aborted)
        return true;
      // Fall through to retry operation.
    }
#endif // defined(EPROTO)
    else
      return true;

    return false;
  }
}

#endif // defined(BOOST_ASIO_HAS_IOCP)

template <typename SockLenType>
inline int call_bind(SockLenType msghdr::*,
    socket_type s, const socket_addr_type* addr, std::size_t addrlen)
{
  return ::bind(s, addr, (SockLenType)addrlen);
}

int bind(socket_type s, const socket_addr_type* addr,
    std::size_t addrlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  clear_last_error();
  int result = error_wrapper(call_bind(
        &msghdr::msg_namelen, s, addr, addrlen), ec);
  if (result == 0)
    ec = boost::system::error_code();
  return result;
}

int close(socket_type s, state_type& state,
    bool destruction, boost::system::error_code& ec)
{
  int result = 0;
  if (s != invalid_socket)
  {
    // We don't want the destructor to block, so set the socket to linger in
    // the background. If the user doesn't like this behaviour then they need
    // to explicitly close the socket.
    if (destruction && (state & user_set_linger))
    {
      ::linger opt;
      opt.l_onoff = 0;
      opt.l_linger = 0;
      boost::system::error_code ignored_ec;
      socket_ops::setsockopt(s, state, SOL_SOCKET,
          SO_LINGER, &opt, sizeof(opt), ignored_ec);
    }

    clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
    result = error_wrapper(::closesocket(s), ec);
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
    result = error_wrapper(::close(s), ec);
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)

    if (result != 0
        && (ec == boost::asio::error::would_block
          || ec == boost::asio::error::try_again))
    {
      // According to UNIX Network Programming Vol. 1, it is possible for
      // close() to fail with EWOULDBLOCK under certain circumstances. What
      // isn't clear is the state of the descriptor after this error. The one
      // current OS where this behaviour is seen, Windows, says that the socket
      // remains open. Therefore we'll put the descriptor back into blocking
      // mode and have another attempt at closing it.
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
      ioctl_arg_type arg = 0;
      ::ioctlsocket(s, FIONBIO, &arg);
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
# if defined(__SYMBIAN32__)
      int flags = ::fcntl(s, F_GETFL, 0);
      if (flags >= 0)
        ::fcntl(s, F_SETFL, flags & ~O_NONBLOCK);
# else // defined(__SYMBIAN32__)
      ioctl_arg_type arg = 0;
      ::ioctl(s, FIONBIO, &arg);
# endif // defined(__SYMBIAN32__)
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
      state &= ~non_blocking;

      clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
      result = error_wrapper(::closesocket(s), ec);
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
      result = error_wrapper(::close(s), ec);
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
    }
  }

  if (result == 0)
    ec = boost::system::error_code();
  return result;
}

bool set_user_non_blocking(socket_type s,
    state_type& state, bool value, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return false;
  }

  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  ioctl_arg_type arg = (value ? 1 : 0);
  int result = error_wrapper(::ioctlsocket(s, FIONBIO, &arg), ec);
#elif defined(__SYMBIAN32__)
  int result = error_wrapper(::fcntl(s, F_GETFL, 0), ec);
  if (result >= 0)
  {
    clear_last_error();
    int flag = (value ? (result | O_NONBLOCK) : (result & ~O_NONBLOCK));
    result = error_wrapper(::fcntl(s, F_SETFL, flag), ec);
  }
#else
  ioctl_arg_type arg = (value ? 1 : 0);
  int result = error_wrapper(::ioctl(s, FIONBIO, &arg), ec);
#endif

  if (result >= 0)
  {
    ec = boost::system::error_code();
    if (value)
      state |= user_set_non_blocking;
    else
    {
      // Clearing the user-set non-blocking mode always overrides any
      // internally-set non-blocking flag. Any subsequent asynchronous
      // operations will need to re-enable non-blocking I/O.
      state &= ~(user_set_non_blocking | internal_non_blocking);
    }
    return true;
  }

  return false;
}

bool set_internal_non_blocking(socket_type s,
    state_type& state, bool value, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return false;
  }

  if (!value && (state & user_set_non_blocking))
  {
    // It does not make sense to clear the internal non-blocking flag if the
    // user still wants non-blocking behaviour. Return an error and let the
    // caller figure out whether to update the user-set non-blocking flag.
    ec = boost::asio::error::invalid_argument;
    return false;
  }

  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  ioctl_arg_type arg = (value ? 1 : 0);
  int result = error_wrapper(::ioctlsocket(s, FIONBIO, &arg), ec);
#elif defined(__SYMBIAN32__)
  int result = error_wrapper(::fcntl(s, F_GETFL, 0), ec);
  if (result >= 0)
  {
    clear_last_error();
    int flag = (value ? (result | O_NONBLOCK) : (result & ~O_NONBLOCK));
    result = error_wrapper(::fcntl(s, F_SETFL, flag), ec);
  }
#else
  ioctl_arg_type arg = (value ? 1 : 0);
  int result = error_wrapper(::ioctl(s, FIONBIO, &arg), ec);
#endif

  if (result >= 0)
  {
    ec = boost::system::error_code();
    if (value)
      state |= internal_non_blocking;
    else
      state &= ~internal_non_blocking;
    return true;
  }

  return false;
}

int shutdown(socket_type s, int what, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  clear_last_error();
  int result = error_wrapper(::shutdown(s, what), ec);
  if (result == 0)
    ec = boost::system::error_code();
  return result;
}

template <typename SockLenType>
inline int call_connect(SockLenType msghdr::*,
    socket_type s, const socket_addr_type* addr, std::size_t addrlen)
{
  return ::connect(s, addr, (SockLenType)addrlen);
}

int connect(socket_type s, const socket_addr_type* addr,
    std::size_t addrlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  clear_last_error();
  int result = error_wrapper(call_connect(
        &msghdr::msg_namelen, s, addr, addrlen), ec);
  if (result == 0)
    ec = boost::system::error_code();
  return result;
}

void sync_connect(socket_type s, const socket_addr_type* addr,
    std::size_t addrlen, boost::system::error_code& ec)
{
  // Perform the connect operation.
  socket_ops::connect(s, addr, addrlen, ec);
  if (ec != boost::asio::error::in_progress
      && ec != boost::asio::error::would_block)
  {
    // The connect operation finished immediately.
    return;
  }

  // Wait for socket to become ready.
  if (socket_ops::poll_connect(s, ec) < 0)
    return;

  // Get the error code from the connect operation.
  int connect_error = 0;
  size_t connect_error_len = sizeof(connect_error);
  if (socket_ops::getsockopt(s, 0, SOL_SOCKET, SO_ERROR,
        &connect_error, &connect_error_len, ec) == socket_error_retval)
    return;

  // Return the result of the connect operation.
  ec = boost::system::error_code(connect_error,
      boost::asio::error::get_system_category());
}

bool non_blocking_connect(socket_type s, boost::system::error_code& ec)
{
  // Get the error code from the connect operation.
  int connect_error = 0;
  size_t connect_error_len = sizeof(connect_error);
  if (socket_ops::getsockopt(s, 0, SOL_SOCKET, SO_ERROR,
        &connect_error, &connect_error_len, ec) == 0)
  {
    if (connect_error)
    {
      ec = boost::system::error_code(connect_error,
          boost::asio::error::get_system_category());
    }
    else
      ec = boost::system::error_code();
  }

  return true;
}

int socketpair(int af, int type, int protocol,
    socket_type sv[2], boost::system::error_code& ec)
{
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  (void)(af);
  (void)(type);
  (void)(protocol);
  (void)(sv);
  ec = boost::asio::error::operation_not_supported;
  return socket_error_retval;
#else
  clear_last_error();
  int result = error_wrapper(::socketpair(af, type, protocol, sv), ec);
  if (result == 0)
    ec = boost::system::error_code();
  return result;
#endif
}

bool sockatmark(socket_type s, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return false;
  }

#if defined(SIOCATMARK)
  ioctl_arg_type value = 0;
# if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  int result = error_wrapper(::ioctlsocket(s, SIOCATMARK, &value), ec);
# else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  int result = error_wrapper(::ioctl(s, SIOCATMARK, &value), ec);
# endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  if (result == 0)
    ec = boost::system::error_code();
# if defined(ENOTTY)
  if (ec.value() == ENOTTY)
    ec = boost::asio::error::not_socket;
# endif // defined(ENOTTY)
#else // defined(SIOCATMARK)
  int value = error_wrapper(::sockatmark(s), ec);
  if (value != -1)
    ec = boost::system::error_code();
#endif // defined(SIOCATMARK)

  return ec ? false : value != 0;
}

size_t available(socket_type s, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return 0;
  }

  ioctl_arg_type value = 0;
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  int result = error_wrapper(::ioctlsocket(s, FIONREAD, &value), ec);
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  int result = error_wrapper(::ioctl(s, FIONREAD, &value), ec);
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  if (result == 0)
    ec = boost::system::error_code();
#if defined(ENOTTY)
  if (ec.value() == ENOTTY)
    ec = boost::asio::error::not_socket;
#endif // defined(ENOTTY)

  return ec ? static_cast<size_t>(0) : static_cast<size_t>(value);
}

int listen(socket_type s, int backlog, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  clear_last_error();
  int result = error_wrapper(::listen(s, backlog), ec);
  if (result == 0)
    ec = boost::system::error_code();
  return result;
}

inline void init_buf_iov_base(void*& base, void* addr)
{
  base = addr;
}

template <typename T>
inline void init_buf_iov_base(T& base, void* addr)
{
  base = static_cast<T>(addr);
}

#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
typedef WSABUF buf;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
typedef iovec buf;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)

void init_buf(buf& b, void* data, size_t size)
{
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  b.buf = static_cast<char*>(data);
  b.len = static_cast<u_long>(size);
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  init_buf_iov_base(b.iov_base, data);
  b.iov_len = size;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

void init_buf(buf& b, const void* data, size_t size)
{
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  b.buf = static_cast<char*>(const_cast<void*>(data));
  b.len = static_cast<u_long>(size);
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  init_buf_iov_base(b.iov_base, const_cast<void*>(data));
  b.iov_len = size;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

inline void init_msghdr_msg_name(void*& name, socket_addr_type* addr)
{
  name = addr;
}

inline void init_msghdr_msg_name(void*& name, const socket_addr_type* addr)
{
  name = const_cast<socket_addr_type*>(addr);
}

template <typename T>
inline void init_msghdr_msg_name(T& name, socket_addr_type* addr)
{
  name = reinterpret_cast<T>(addr);
}

template <typename T>
inline void init_msghdr_msg_name(T& name, const socket_addr_type* addr)
{
  name = reinterpret_cast<T>(const_cast<socket_addr_type*>(addr));
}

int recv(socket_type s, buf* bufs, size_t count, int flags,
    boost::system::error_code& ec)
{
  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  // Receive some data.
  DWORD recv_buf_count = static_cast<DWORD>(count);
  DWORD bytes_transferred = 0;
  DWORD recv_flags = flags;
  int result = error_wrapper(::WSARecv(s, bufs,
        recv_buf_count, &bytes_transferred, &recv_flags, 0, 0), ec);
  if (ec.value() == ERROR_NETNAME_DELETED)
    ec = boost::asio::error::connection_reset;
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
    ec = boost::asio::error::connection_refused;
  if (result != 0)
    return socket_error_retval;
  ec = boost::system::error_code();
  return bytes_transferred;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  msghdr msg = msghdr();
  msg.msg_iov = bufs;
  msg.msg_iovlen = count;
  int result = error_wrapper(::recvmsg(s, &msg, flags), ec);
  if (result >= 0)
    ec = boost::system::error_code();
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

size_t sync_recv(socket_type s, state_type state, buf* bufs,
    size_t count, int flags, bool all_empty, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return 0;
  }

  // A request to read 0 bytes on a stream is a no-op.
  if (all_empty && (state & stream_oriented))
  {
    ec = boost::system::error_code();
    return 0;
  }

  // Read some data.
  for (;;)
  {
    // Try to complete the operation without blocking.
    int bytes = socket_ops::recv(s, bufs, count, flags, ec);

    // Check if operation succeeded.
    if (bytes > 0)
      return bytes;

    // Check for EOF.
    if ((state & stream_oriented) && bytes == 0)
    {
      ec = boost::asio::error::eof;
      return 0;
    }

    // Operation failed.
    if ((state & user_set_non_blocking)
        || (ec != boost::asio::error::would_block
          && ec != boost::asio::error::try_again))
      return 0;

    // Wait for socket to become ready.
    if (socket_ops::poll_read(s, ec) < 0)
      return 0;
  }
}

#if defined(BOOST_ASIO_HAS_IOCP)

void complete_iocp_recv(state_type state,
    const weak_cancel_token_type& cancel_token, bool all_empty,
    boost::system::error_code& ec, size_t bytes_transferred)
{
  // Map non-portable errors to their portable counterparts.
  if (ec.value() == ERROR_NETNAME_DELETED)
  {
    if (cancel_token.expired())
      ec = boost::asio::error::operation_aborted;
    else
      ec = boost::asio::error::connection_reset;
  }
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
  {
    ec = boost::asio::error::connection_refused;
  }

  // Check for connection closed.
  else if (!ec && bytes_transferred == 0
      && (state & stream_oriented) != 0
      && !all_empty)
  {
    ec = boost::asio::error::eof;
  }
}

#else // defined(BOOST_ASIO_HAS_IOCP)

bool non_blocking_recv(socket_type s,
    buf* bufs, size_t count, int flags, bool is_stream,
    boost::system::error_code& ec, size_t& bytes_transferred)
{
  for (;;)
  {
    // Read some data.
    int bytes = socket_ops::recv(s, bufs, count, flags, ec);

    // Check for end of stream.
    if (is_stream && bytes == 0)
    {
      ec = boost::asio::error::eof;
      return true;
    }

    // Retry operation if interrupted by signal.
    if (ec == boost::asio::error::interrupted)
      continue;

    // Check if we need to run the operation again.
    if (ec == boost::asio::error::would_block
        || ec == boost::asio::error::try_again)
      return false;

    // Operation is complete.
    if (bytes >= 0)
    {
      ec = boost::system::error_code();
      bytes_transferred = bytes;
    }
    else
      bytes_transferred = 0;

    return true;
  }
}

#endif // defined(BOOST_ASIO_HAS_IOCP)

int recvfrom(socket_type s, buf* bufs, size_t count, int flags,
    socket_addr_type* addr, std::size_t* addrlen,
    boost::system::error_code& ec)
{
  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  // Receive some data.
  DWORD recv_buf_count = static_cast<DWORD>(count);
  DWORD bytes_transferred = 0;
  DWORD recv_flags = flags;
  int tmp_addrlen = (int)*addrlen;
  int result = error_wrapper(::WSARecvFrom(s, bufs, recv_buf_count,
        &bytes_transferred, &recv_flags, addr, &tmp_addrlen, 0, 0), ec);
  *addrlen = (std::size_t)tmp_addrlen;
  if (ec.value() == ERROR_NETNAME_DELETED)
    ec = boost::asio::error::connection_reset;
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
    ec = boost::asio::error::connection_refused;
  if (result != 0)
    return socket_error_retval;
  ec = boost::system::error_code();
  return bytes_transferred;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  msghdr msg = msghdr();
  init_msghdr_msg_name(msg.msg_name, addr);
  msg.msg_namelen = *addrlen;
  msg.msg_iov = bufs;
  msg.msg_iovlen = count;
  int result = error_wrapper(::recvmsg(s, &msg, flags), ec);
  *addrlen = msg.msg_namelen;
  if (result >= 0)
    ec = boost::system::error_code();
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

size_t sync_recvfrom(socket_type s, state_type state, buf* bufs,
    size_t count, int flags, socket_addr_type* addr,
    std::size_t* addrlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return 0;
  }

  // Read some data.
  for (;;)
  {
    // Try to complete the operation without blocking.
    int bytes = socket_ops::recvfrom(s, bufs, count, flags, addr, addrlen, ec);

    // Check if operation succeeded.
    if (bytes >= 0)
      return bytes;

    // Operation failed.
    if ((state & user_set_non_blocking)
        || (ec != boost::asio::error::would_block
          && ec != boost::asio::error::try_again))
      return 0;

    // Wait for socket to become ready.
    if (socket_ops::poll_read(s, ec) < 0)
      return 0;
  }
}

#if defined(BOOST_ASIO_HAS_IOCP)

void complete_iocp_recvfrom(
    const weak_cancel_token_type& cancel_token,
    boost::system::error_code& ec)
{
  // Map non-portable errors to their portable counterparts.
  if (ec.value() == ERROR_NETNAME_DELETED)
  {
    if (cancel_token.expired())
      ec = boost::asio::error::operation_aborted;
    else
      ec = boost::asio::error::connection_reset;
  }
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
  {
    ec = boost::asio::error::connection_refused;
  }
}

#else // defined(BOOST_ASIO_HAS_IOCP)

bool non_blocking_recvfrom(socket_type s,
    buf* bufs, size_t count, int flags,
    socket_addr_type* addr, std::size_t* addrlen,
    boost::system::error_code& ec, size_t& bytes_transferred)
{
  for (;;)
  {
    // Read some data.
    int bytes = socket_ops::recvfrom(s, bufs, count, flags, addr, addrlen, ec);

    // Retry operation if interrupted by signal.
    if (ec == boost::asio::error::interrupted)
      continue;

    // Check if we need to run the operation again.
    if (ec == boost::asio::error::would_block
        || ec == boost::asio::error::try_again)
      return false;

    // Operation is complete.
    if (bytes >= 0)
    {
      ec = boost::system::error_code();
      bytes_transferred = bytes;
    }
    else
      bytes_transferred = 0;

    return true;
  }
}

#endif // defined(BOOST_ASIO_HAS_IOCP)

int recvmsg(socket_type s, buf* bufs, size_t count,
    int in_flags, int& out_flags, boost::system::error_code& ec)
{
  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  out_flags = 0;
  return socket_ops::recv(s, bufs, count, in_flags, ec);
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  msghdr msg = msghdr();
  msg.msg_iov = bufs;
  msg.msg_iovlen = count;
  int result = error_wrapper(::recvmsg(s, &msg, in_flags), ec);
  if (result >= 0)
  {
    ec = boost::system::error_code();
    out_flags = msg.msg_flags;
  }
  else
    out_flags = 0;
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

size_t sync_recvmsg(socket_type s, state_type state,
    buf* bufs, size_t count, int in_flags, int& out_flags,
    boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return 0;
  }

  // Read some data.
  for (;;)
  {
    // Try to complete the operation without blocking.
    int bytes = socket_ops::recvmsg(s, bufs, count, in_flags, out_flags, ec);

    // Check if operation succeeded.
    if (bytes >= 0)
      return bytes;

    // Operation failed.
    if ((state & user_set_non_blocking)
        || (ec != boost::asio::error::would_block
          && ec != boost::asio::error::try_again))
      return 0;

    // Wait for socket to become ready.
    if (socket_ops::poll_read(s, ec) < 0)
      return 0;
  }
}

#if defined(BOOST_ASIO_HAS_IOCP)

void complete_iocp_recvmsg(
    const weak_cancel_token_type& cancel_token,
    boost::system::error_code& ec)
{
  // Map non-portable errors to their portable counterparts.
  if (ec.value() == ERROR_NETNAME_DELETED)
  {
    if (cancel_token.expired())
      ec = boost::asio::error::operation_aborted;
    else
      ec = boost::asio::error::connection_reset;
  }
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
  {
    ec = boost::asio::error::connection_refused;
  }
}

#else // defined(BOOST_ASIO_HAS_IOCP)

bool non_blocking_recvmsg(socket_type s,
    buf* bufs, size_t count, int in_flags, int& out_flags,
    boost::system::error_code& ec, size_t& bytes_transferred)
{
  for (;;)
  {
    // Read some data.
    int bytes = socket_ops::recvmsg(s, bufs, count, in_flags, out_flags, ec);

    // Retry operation if interrupted by signal.
    if (ec == boost::asio::error::interrupted)
      continue;

    // Check if we need to run the operation again.
    if (ec == boost::asio::error::would_block
        || ec == boost::asio::error::try_again)
      return false;

    // Operation is complete.
    if (bytes >= 0)
    {
      ec = boost::system::error_code();
      bytes_transferred = bytes;
    }
    else
      bytes_transferred = 0;

    return true;
  }
}

#endif // defined(BOOST_ASIO_HAS_IOCP)

int send(socket_type s, const buf* bufs, size_t count, int flags,
    boost::system::error_code& ec)
{
  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  // Send the data.
  DWORD send_buf_count = static_cast<DWORD>(count);
  DWORD bytes_transferred = 0;
  DWORD send_flags = flags;
  int result = error_wrapper(::WSASend(s, const_cast<buf*>(bufs),
        send_buf_count, &bytes_transferred, send_flags, 0, 0), ec);
  if (ec.value() == ERROR_NETNAME_DELETED)
    ec = boost::asio::error::connection_reset;
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
    ec = boost::asio::error::connection_refused;
  if (result != 0)
    return socket_error_retval;
  ec = boost::system::error_code();
  return bytes_transferred;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  msghdr msg = msghdr();
  msg.msg_iov = const_cast<buf*>(bufs);
  msg.msg_iovlen = count;
#if defined(__linux__)
  flags |= MSG_NOSIGNAL;
#endif // defined(__linux__)
  int result = error_wrapper(::sendmsg(s, &msg, flags), ec);
  if (result >= 0)
    ec = boost::system::error_code();
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

size_t sync_send(socket_type s, state_type state, const buf* bufs,
    size_t count, int flags, bool all_empty, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return 0;
  }

  // A request to write 0 bytes to a stream is a no-op.
  if (all_empty && (state & stream_oriented))
  {
    ec = boost::system::error_code();
    return 0;
  }

  // Read some data.
  for (;;)
  {
    // Try to complete the operation without blocking.
    int bytes = socket_ops::send(s, bufs, count, flags, ec);

    // Check if operation succeeded.
    if (bytes >= 0)
      return bytes;

    // Operation failed.
    if ((state & user_set_non_blocking)
        || (ec != boost::asio::error::would_block
          && ec != boost::asio::error::try_again))
      return 0;

    // Wait for socket to become ready.
    if (socket_ops::poll_write(s, ec) < 0)
      return 0;
  }
}

#if defined(BOOST_ASIO_HAS_IOCP)

void complete_iocp_send(
    const weak_cancel_token_type& cancel_token,
    boost::system::error_code& ec)
{
  // Map non-portable errors to their portable counterparts.
  if (ec.value() == ERROR_NETNAME_DELETED)
  {
    if (cancel_token.expired())
      ec = boost::asio::error::operation_aborted;
    else
      ec = boost::asio::error::connection_reset;
  }
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
  {
    ec = boost::asio::error::connection_refused;
  }
}

#else // defined(BOOST_ASIO_HAS_IOCP)

bool non_blocking_send(socket_type s,
    const buf* bufs, size_t count, int flags,
    boost::system::error_code& ec, size_t& bytes_transferred)
{
  for (;;)
  {
    // Write some data.
    int bytes = socket_ops::send(s, bufs, count, flags, ec);

    // Retry operation if interrupted by signal.
    if (ec == boost::asio::error::interrupted)
      continue;

    // Check if we need to run the operation again.
    if (ec == boost::asio::error::would_block
        || ec == boost::asio::error::try_again)
      return false;

    // Operation is complete.
    if (bytes >= 0)
    {
      ec = boost::system::error_code();
      bytes_transferred = bytes;
    }
    else
      bytes_transferred = 0;

    return true;
  }
}

#endif // defined(BOOST_ASIO_HAS_IOCP)

int sendto(socket_type s, const buf* bufs, size_t count, int flags,
    const socket_addr_type* addr, std::size_t addrlen,
    boost::system::error_code& ec)
{
  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  // Send the data.
  DWORD send_buf_count = static_cast<DWORD>(count);
  DWORD bytes_transferred = 0;
  int result = error_wrapper(::WSASendTo(s, const_cast<buf*>(bufs),
        send_buf_count, &bytes_transferred, flags, addr,
        static_cast<int>(addrlen), 0, 0), ec);
  if (ec.value() == ERROR_NETNAME_DELETED)
    ec = boost::asio::error::connection_reset;
  else if (ec.value() == ERROR_PORT_UNREACHABLE)
    ec = boost::asio::error::connection_refused;
  if (result != 0)
    return socket_error_retval;
  ec = boost::system::error_code();
  return bytes_transferred;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  msghdr msg = msghdr();
  init_msghdr_msg_name(msg.msg_name, addr);
  msg.msg_namelen = addrlen;
  msg.msg_iov = const_cast<buf*>(bufs);
  msg.msg_iovlen = count;
#if defined(__linux__)
  flags |= MSG_NOSIGNAL;
#endif // defined(__linux__)
  int result = error_wrapper(::sendmsg(s, &msg, flags), ec);
  if (result >= 0)
    ec = boost::system::error_code();
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

size_t sync_sendto(socket_type s, state_type state, const buf* bufs,
    size_t count, int flags, const socket_addr_type* addr,
    std::size_t addrlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return 0;
  }

  // Write some data.
  for (;;)
  {
    // Try to complete the operation without blocking.
    int bytes = socket_ops::sendto(s, bufs, count, flags, addr, addrlen, ec);

    // Check if operation succeeded.
    if (bytes >= 0)
      return bytes;

    // Operation failed.
    if ((state & user_set_non_blocking)
        || (ec != boost::asio::error::would_block
          && ec != boost::asio::error::try_again))
      return 0;

    // Wait for socket to become ready.
    if (socket_ops::poll_write(s, ec) < 0)
      return 0;
  }
}

#if !defined(BOOST_ASIO_HAS_IOCP)

bool non_blocking_sendto(socket_type s,
    const buf* bufs, size_t count, int flags,
    const socket_addr_type* addr, std::size_t addrlen,
    boost::system::error_code& ec, size_t& bytes_transferred)
{
  for (;;)
  {
    // Write some data.
    int bytes = socket_ops::sendto(s, bufs, count, flags, addr, addrlen, ec);

    // Retry operation if interrupted by signal.
    if (ec == boost::asio::error::interrupted)
      continue;

    // Check if we need to run the operation again.
    if (ec == boost::asio::error::would_block
        || ec == boost::asio::error::try_again)
      return false;

    // Operation is complete.
    if (bytes >= 0)
    {
      ec = boost::system::error_code();
      bytes_transferred = bytes;
    }
    else
      bytes_transferred = 0;

    return true;
  }
}

#endif // !defined(BOOST_ASIO_HAS_IOCP)

socket_type socket(int af, int type, int protocol,
    boost::system::error_code& ec)
{
  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  socket_type s = error_wrapper(::WSASocket(af, type, protocol, 0, 0,
        WSA_FLAG_OVERLAPPED), ec);
  if (s == invalid_socket)
    return s;

  if (af == AF_INET6)
  {
    // Try to enable the POSIX default behaviour of having IPV6_V6ONLY set to
    // false. This will only succeed on Windows Vista and later versions of
    // Windows, where a dual-stack IPv4/v6 implementation is available.
    DWORD optval = 0;
    ::setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
        reinterpret_cast<const char*>(&optval), sizeof(optval));
  }

  ec = boost::system::error_code();

  return s;
#elif defined(__MACH__) && defined(__APPLE__) || defined(__FreeBSD__)
  socket_type s = error_wrapper(::socket(af, type, protocol), ec);
  if (s == invalid_socket)
    return s;

  int optval = 1;
  int result = error_wrapper(::setsockopt(s,
        SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval)), ec);
  if (result != 0)
  {
    ::close(s);
    return invalid_socket;
  }

  return s;
#else
  int s = error_wrapper(::socket(af, type, protocol), ec);
  if (s >= 0)
    ec = boost::system::error_code();
  return s;
#endif
}

template <typename SockLenType>
inline int call_setsockopt(SockLenType msghdr::*,
    socket_type s, int level, int optname,
    const void* optval, std::size_t optlen)
{
  return ::setsockopt(s, level, optname,
      (const char*)optval, (SockLenType)optlen);
}

int setsockopt(socket_type s, state_type& state, int level, int optname,
    const void* optval, std::size_t optlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  if (level == custom_socket_option_level && optname == always_fail_option)
  {
    ec = boost::asio::error::invalid_argument;
    return socket_error_retval;
  }

  if (level == custom_socket_option_level
      && optname == enable_connection_aborted_option)
  {
    if (optlen != sizeof(int))
    {
      ec = boost::asio::error::invalid_argument;
      return socket_error_retval;
    }

    if (*static_cast<const int*>(optval))
      state |= enable_connection_aborted;
    else
      state &= ~enable_connection_aborted;
    ec = boost::system::error_code();
    return 0;
  }

  if (level == SOL_SOCKET && optname == SO_LINGER)
    state |= user_set_linger;

#if defined(__BORLANDC__)
  // Mysteriously, using the getsockopt and setsockopt functions directly with
  // Borland C++ results in incorrect values being set and read. The bug can be
  // worked around by using function addresses resolved with GetProcAddress.
  if (HMODULE winsock_module = ::GetModuleHandleA("ws2_32"))
  {
    typedef int (WSAAPI *sso_t)(SOCKET, int, int, const char*, int);
    if (sso_t sso = (sso_t)::GetProcAddress(winsock_module, "setsockopt"))
    {
      clear_last_error();
      return error_wrapper(sso(s, level, optname,
            reinterpret_cast<const char*>(optval),
            static_cast<int>(optlen)), ec);
    }
  }
  ec = boost::asio::error::fault;
  return socket_error_retval;
#else // defined(__BORLANDC__)
  clear_last_error();
  int result = error_wrapper(call_setsockopt(&msghdr::msg_namelen,
        s, level, optname, optval, optlen), ec);
  if (result == 0)
  {
    ec = boost::system::error_code();

#if defined(__MACH__) && defined(__APPLE__) \
  || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
    // To implement portable behaviour for SO_REUSEADDR with UDP sockets we
    // need to also set SO_REUSEPORT on BSD-based platforms.
    if ((state & datagram_oriented)
        && level == SOL_SOCKET && optname == SO_REUSEADDR)
    {
      call_setsockopt(&msghdr::msg_namelen, s,
          SOL_SOCKET, SO_REUSEPORT, optval, optlen);
    }
#endif
  }

  return result;
#endif // defined(__BORLANDC__)
}

template <typename SockLenType>
inline int call_getsockopt(SockLenType msghdr::*,
    socket_type s, int level, int optname,
    void* optval, std::size_t* optlen)
{
  SockLenType tmp_optlen = (SockLenType)*optlen;
  int result = ::getsockopt(s, level, optname, (char*)optval, &tmp_optlen);
  *optlen = (std::size_t)tmp_optlen;
  return result;
}

int getsockopt(socket_type s, state_type state, int level, int optname,
    void* optval, size_t* optlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  if (level == custom_socket_option_level && optname == always_fail_option)
  {
    ec = boost::asio::error::invalid_argument;
    return socket_error_retval;
  }

  if (level == custom_socket_option_level
      && optname == enable_connection_aborted_option)
  {
    if (*optlen != sizeof(int))
    {
      ec = boost::asio::error::invalid_argument;
      return socket_error_retval;
    }

    *static_cast<int*>(optval) = (state & enable_connection_aborted) ? 1 : 0;
    ec = boost::system::error_code();
    return 0;
  }

#if defined(__BORLANDC__)
  // Mysteriously, using the getsockopt and setsockopt functions directly with
  // Borland C++ results in incorrect values being set and read. The bug can be
  // worked around by using function addresses resolved with GetProcAddress.
  if (HMODULE winsock_module = ::GetModuleHandleA("ws2_32"))
  {
    typedef int (WSAAPI *gso_t)(SOCKET, int, int, char*, int*);
    if (gso_t gso = (gso_t)::GetProcAddress(winsock_module, "getsockopt"))
    {
      clear_last_error();
      int tmp_optlen = static_cast<int>(*optlen);
      int result = error_wrapper(gso(s, level, optname,
            reinterpret_cast<char*>(optval), &tmp_optlen), ec);
      *optlen = static_cast<size_t>(tmp_optlen);
      if (result != 0 && level == IPPROTO_IPV6 && optname == IPV6_V6ONLY
          && ec.value() == WSAENOPROTOOPT && *optlen == sizeof(DWORD))
      {
        // Dual-stack IPv4/v6 sockets, and the IPV6_V6ONLY socket option, are
        // only supported on Windows Vista and later. To simplify program logic
        // we will fake success of getting this option and specify that the
        // value is non-zero (i.e. true). This corresponds to the behavior of
        // IPv6 sockets on Windows platforms pre-Vista.
        *static_cast<DWORD*>(optval) = 1;
        ec = boost::system::error_code();
      }
      return result;
    }
  }
  ec = boost::asio::error::fault;
  return socket_error_retval;
#elif defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  clear_last_error();
  int result = error_wrapper(call_getsockopt(&msghdr::msg_namelen,
        s, level, optname, optval, optlen), ec);
  if (result != 0 && level == IPPROTO_IPV6 && optname == IPV6_V6ONLY
      && ec.value() == WSAENOPROTOOPT && *optlen == sizeof(DWORD))
  {
    // Dual-stack IPv4/v6 sockets, and the IPV6_V6ONLY socket option, are only
    // supported on Windows Vista and later. To simplify program logic we will
    // fake success of getting this option and specify that the value is
    // non-zero (i.e. true). This corresponds to the behavior of IPv6 sockets
    // on Windows platforms pre-Vista.
    *static_cast<DWORD*>(optval) = 1;
    ec = boost::system::error_code();
  }
  if (result == 0)
    ec = boost::system::error_code();
  return result;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  clear_last_error();
  int result = error_wrapper(call_getsockopt(&msghdr::msg_namelen,
        s, level, optname, optval, optlen), ec);
#if defined(__linux__)
  if (result == 0 && level == SOL_SOCKET && *optlen == sizeof(int)
      && (optname == SO_SNDBUF || optname == SO_RCVBUF))
  {
    // On Linux, setting SO_SNDBUF or SO_RCVBUF to N actually causes the kernel
    // to set the buffer size to N*2. Linux puts additional stuff into the
    // buffers so that only about half is actually available to the application.
    // The retrieved value is divided by 2 here to make it appear as though the
    // correct value has been set.
    *static_cast<int*>(optval) /= 2;
  }
#endif // defined(__linux__)
  if (result == 0)
    ec = boost::system::error_code();
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

template <typename SockLenType>
inline int call_getpeername(SockLenType msghdr::*,
    socket_type s, socket_addr_type* addr, std::size_t* addrlen)
{
  SockLenType tmp_addrlen = (SockLenType)*addrlen;
  int result = ::getpeername(s, addr, &tmp_addrlen);
  *addrlen = (std::size_t)tmp_addrlen;
  return result;
}

int getpeername(socket_type s, socket_addr_type* addr,
    std::size_t* addrlen, bool cached, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  if (cached)
  {
    // Check if socket is still connected.
    DWORD connect_time = 0;
    size_t connect_time_len = sizeof(connect_time);
    if (socket_ops::getsockopt(s, 0, SOL_SOCKET, SO_CONNECT_TIME,
          &connect_time, &connect_time_len, ec) == socket_error_retval)
    {
      return socket_error_retval;
    }
    if (connect_time == 0xFFFFFFFF)
    {
      ec = boost::asio::error::not_connected;
      return socket_error_retval;
    }

    // The cached value is still valid.
    ec = boost::system::error_code();
    return 0;
  }
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  (void)cached;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)

  clear_last_error();
  int result = error_wrapper(call_getpeername(
        &msghdr::msg_namelen, s, addr, addrlen), ec);
  if (result == 0)
    ec = boost::system::error_code();
  return result;
}

template <typename SockLenType>
inline int call_getsockname(SockLenType msghdr::*,
    socket_type s, socket_addr_type* addr, std::size_t* addrlen)
{
  SockLenType tmp_addrlen = (SockLenType)*addrlen;
  int result = ::getsockname(s, addr, &tmp_addrlen);
  *addrlen = (std::size_t)tmp_addrlen;
  return result;
}

int getsockname(socket_type s, socket_addr_type* addr,
    std::size_t* addrlen, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  clear_last_error();
  int result = error_wrapper(call_getsockname(
        &msghdr::msg_namelen, s, addr, addrlen), ec);
  if (result == 0)
    ec = boost::system::error_code();
  return result;
}

int ioctl(socket_type s, state_type& state, int cmd,
    ioctl_arg_type* arg, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  int result = error_wrapper(::ioctlsocket(s, cmd, arg), ec);
#elif defined(__MACH__) && defined(__APPLE__) \
  || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
  int result = error_wrapper(::ioctl(s,
        static_cast<unsigned int>(cmd), arg), ec);
#else
  int result = error_wrapper(::ioctl(s, cmd, arg), ec);
#endif
  if (result >= 0)
  {
    ec = boost::system::error_code();

    // When updating the non-blocking mode we always perform the ioctl syscall,
    // even if the flags would otherwise indicate that the socket is already in
    // the correct state. This ensures that the underlying socket is put into
    // the state that has been requested by the user. If the ioctl syscall was
    // successful then we need to update the flags to match.
    if (cmd == static_cast<int>(FIONBIO))
    {
      if (*arg)
      {
        state |= user_set_non_blocking;
      }
      else
      {
        // Clearing the non-blocking mode always overrides any internally-set
        // non-blocking flag. Any subsequent asynchronous operations will need
        // to re-enable non-blocking I/O.
        state &= ~(user_set_non_blocking | internal_non_blocking);
      }
    }
  }

  return result;
}

int select(int nfds, fd_set* readfds, fd_set* writefds,
    fd_set* exceptfds, timeval* timeout, boost::system::error_code& ec)
{
  clear_last_error();
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  if (!readfds && !writefds && !exceptfds && timeout)
  {
    DWORD milliseconds = timeout->tv_sec * 1000 + timeout->tv_usec / 1000;
    if (milliseconds == 0)
      milliseconds = 1; // Force context switch.
    ::Sleep(milliseconds);
    ec = boost::system::error_code();
    return 0;
  }

  // The select() call allows timeout values measured in microseconds, but the
  // system clock (as wrapped by boost::posix_time::microsec_clock) typically
  // has a resolution of 10 milliseconds. This can lead to a spinning select
  // reactor, meaning increased CPU usage, when waiting for the earliest
  // scheduled timeout if it's less than 10 milliseconds away. To avoid a tight
  // spin we'll use a minimum timeout of 1 millisecond.
  if (timeout && timeout->tv_sec == 0
      && timeout->tv_usec > 0 && timeout->tv_usec < 1000)
    timeout->tv_usec = 1000;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)

#if defined(__hpux) && defined(__SELECT)
  timespec ts;
  ts.tv_sec = timeout ? timeout->tv_sec : 0;
  ts.tv_nsec = timeout ? timeout->tv_usec * 1000 : 0;
  return error_wrapper(::pselect(nfds, readfds,
        writefds, exceptfds, timeout ? &ts : 0, 0), ec);
#else
  int result = error_wrapper(::select(nfds, readfds,
        writefds, exceptfds, timeout), ec);
  if (result >= 0)
    ec = boost::system::error_code();
  return result;
#endif
}

int poll_read(socket_type s, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

#if defined(BOOST_WINDOWS) \
  || defined(__CYGWIN__) \
  || defined(__SYMBIAN32__)
  fd_set fds;
  FD_ZERO(&fds);
  FD_SET(s, &fds);
  clear_last_error();
  int result = error_wrapper(::select(s, &fds, 0, 0, 0), ec);
  if (result >= 0)
    ec = boost::system::error_code();
  return result;
#else // defined(BOOST_WINDOWS)
      // || defined(__CYGWIN__)
      // || defined(__SYMBIAN32__)
  pollfd fds;
  fds.fd = s;
  fds.events = POLLIN;
  fds.revents = 0;
  clear_last_error();
  int result = error_wrapper(::poll(&fds, 1, -1), ec);
  if (result >= 0)
    ec = boost::system::error_code();
  return result;
#endif // defined(BOOST_WINDOWS)
       // || defined(__CYGWIN__)
       // || defined(__SYMBIAN32__)
}

int poll_write(socket_type s, boost::system::error_code& ec)
{
  if (s == invalid_socket)
  {
    ec = boost::asio::error::bad_descriptor;
    return socket_error_retval;
  }

#if defined(BOOST_WINDOWS) \
  || defined(__CYGWIN__) \
  || defined(__SYMBIAN3…