socket_ops.hpp

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  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_error(ec);
      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;
        clear_error(ec);
      }
      return result;
    }
  }
  ec = asio::error::fault;
  return -1;
#elif defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  clear_error(ec);
  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;
    clear_error(ec);
  }
# if defined(UNDER_CE)
  if (result == 0)
    clear_error(ec);
# endif
  return result;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  clear_error(ec);
  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__)
  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;
}

inline int getpeername(socket_type s, socket_addr_type* addr,
    std::size_t* addrlen, asio::error_code& ec)
{
  clear_error(ec);
  int result = error_wrapper(call_getpeername(
        &msghdr::msg_namelen, s, addr, addrlen), ec);
#if defined(BOOST_WINDOWS) && defined(UNDER_CE)
  if (result == 0)
    clear_error(ec);
#endif
  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;
}

inline int getsockname(socket_type s, socket_addr_type* addr,
    std::size_t* addrlen, asio::error_code& ec)
{
  clear_error(ec);
  int result = error_wrapper(call_getsockname(
        &msghdr::msg_namelen, s, addr, addrlen), ec);
#if defined(BOOST_WINDOWS) && defined(UNDER_CE)
  if (result == 0)
    clear_error(ec);
#endif
  return result;
}

inline int ioctl(socket_type s, long cmd, ioctl_arg_type* arg,
    asio::error_code& ec)
{
  clear_error(ec);
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  int result = error_wrapper(::ioctlsocket(s, cmd, arg), ec);
# if defined(UNDER_CE)
  if (result == 0)
    clear_error(ec);
# endif
  return result;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  return error_wrapper(::ioctl(s, cmd, arg), ec);
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

inline int select(int nfds, fd_set* readfds, fd_set* writefds,
    fd_set* exceptfds, timeval* timeout, asio::error_code& ec)
{
  clear_error(ec);
#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 = asio::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(__HP_aCC)
  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 defined(BOOST_WINDOWS) && defined(UNDER_CE)
  if (result >= 0)
    clear_error(ec);
# endif
  return result;
#endif
}

inline int poll_read(socket_type s, asio::error_code& ec)
{
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  FD_SET fds;
  FD_ZERO(&fds);
  FD_SET(s, &fds);
  clear_error(ec);
  int result = error_wrapper(::select(s, &fds, 0, 0, 0), ec);
# if defined(UNDER_CE)
  if (result >= 0)
    clear_error(ec);
# endif
  return result;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  pollfd fds;
  fds.fd = s;
  fds.events = POLLIN;
  fds.revents = 0;
  clear_error(ec);
  return error_wrapper(::poll(&fds, 1, -1), ec);
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

inline int poll_write(socket_type s, asio::error_code& ec)
{
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  FD_SET fds;
  FD_ZERO(&fds);
  FD_SET(s, &fds);
  clear_error(ec);
  int result = error_wrapper(::select(s, 0, &fds, 0, 0), ec);
# if defined(UNDER_CE)
  if (result >= 0)
    clear_error(ec);
# endif
  return result;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  pollfd fds;
  fds.fd = s;
  fds.events = POLLOUT;
  fds.revents = 0;
  clear_error(ec);
  return error_wrapper(::poll(&fds, 1, -1), ec);
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

inline const char* inet_ntop(int af, const void* src, char* dest, size_t length,
    unsigned long scope_id, asio::error_code& ec)
{
  clear_error(ec);
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  using namespace std; // For memcpy.

  if (af != AF_INET && af != AF_INET6)
  {
    ec = asio::error::address_family_not_supported;
    return 0;
  }

  sockaddr_storage_type address;
  DWORD address_length;
  if (af == AF_INET)
  {
    address_length = sizeof(sockaddr_in4_type);
    sockaddr_in4_type* ipv4_address =
      reinterpret_cast<sockaddr_in4_type*>(&address);
    ipv4_address->sin_family = AF_INET;
    ipv4_address->sin_port = 0;
    memcpy(&ipv4_address->sin_addr, src, sizeof(in4_addr_type));
  }
  else // AF_INET6
  {
    address_length = sizeof(sockaddr_in6_type);
    sockaddr_in6_type* ipv6_address =
      reinterpret_cast<sockaddr_in6_type*>(&address);
    ipv6_address->sin6_family = AF_INET6;
    ipv6_address->sin6_port = 0;
    ipv6_address->sin6_flowinfo = 0;
    ipv6_address->sin6_scope_id = scope_id;
    memcpy(&ipv6_address->sin6_addr, src, sizeof(in6_addr_type));
  }

  DWORD string_length = static_cast<DWORD>(length);
#if defined(BOOST_NO_ANSI_APIS)
  LPWSTR string_buffer = (LPWSTR)_alloca(length * sizeof(WCHAR));
  int result = error_wrapper(::WSAAddressToStringW(
        reinterpret_cast<sockaddr*>(&address),
        address_length, 0, string_buffer, &string_length), ec);
  ::WideCharToMultiByte(CP_ACP, 0, string_buffer, -1, dest, length, 0, 0);
#else
  int result = error_wrapper(::WSAAddressToStringA(
        reinterpret_cast<sockaddr*>(&address),
        address_length, 0, dest, &string_length), ec);
#endif

  // Windows may set error code on success.
  if (result != socket_error_retval)
    clear_error(ec);

  // Windows may not set an error code on failure.
  else if (result == socket_error_retval && !ec)
    ec = asio::error::invalid_argument;

  return result == socket_error_retval ? 0 : dest;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  const char* result = error_wrapper(::inet_ntop(af, src, dest, length), ec);
  if (result == 0 && !ec)
    ec = asio::error::invalid_argument;
  if (result != 0 && af == AF_INET6 && scope_id != 0)
  {
    using namespace std; // For strcat and sprintf.
    char if_name[IF_NAMESIZE + 1] = "%";
    const in6_addr_type* ipv6_address = static_cast<const in6_addr_type*>(src);
    bool is_link_local = IN6_IS_ADDR_LINKLOCAL(ipv6_address);
    if (!is_link_local || if_indextoname(scope_id, if_name + 1) == 0)
      sprintf(if_name + 1, "%lu", scope_id);
    strcat(dest, if_name);
  }
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

inline int inet_pton(int af, const char* src, void* dest,
    unsigned long* scope_id, asio::error_code& ec)
{
  clear_error(ec);
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  using namespace std; // For memcpy and strcmp.

  if (af != AF_INET && af != AF_INET6)
  {
    ec = asio::error::address_family_not_supported;
    return -1;
  }

  sockaddr_storage_type address;
  int address_length = sizeof(sockaddr_storage_type);
#if defined(BOOST_NO_ANSI_APIS)
  int num_wide_chars = strlen(src) + 1;
  LPWSTR wide_buffer = (LPWSTR)_alloca(num_wide_chars * sizeof(WCHAR));
  ::MultiByteToWideChar(CP_ACP, 0, src, -1, wide_buffer, num_wide_chars);
  int result = error_wrapper(::WSAStringToAddressW(
        wide_buffer, af, 0,
        reinterpret_cast<sockaddr*>(&address),
        &address_length), ec);
#else
  int result = error_wrapper(::WSAStringToAddressA(
        const_cast<char*>(src), af, 0,
        reinterpret_cast<sockaddr*>(&address),
        &address_length), ec);
#endif

  if (af == AF_INET)
  {
    if (result != socket_error_retval)
    {
      sockaddr_in4_type* ipv4_address =
        reinterpret_cast<sockaddr_in4_type*>(&address);
      memcpy(dest, &ipv4_address->sin_addr, sizeof(in4_addr_type));
      clear_error(ec);
    }
    else if (strcmp(src, "255.255.255.255") == 0)
    {
      static_cast<in4_addr_type*>(dest)->s_addr = INADDR_NONE;
      clear_error(ec);
    }
  }
  else // AF_INET6
  {
    if (result != socket_error_retval)
    {
      sockaddr_in6_type* ipv6_address =
        reinterpret_cast<sockaddr_in6_type*>(&address);
      memcpy(dest, &ipv6_address->sin6_addr, sizeof(in6_addr_type));
      if (scope_id)
        *scope_id = ipv6_address->sin6_scope_id;
      clear_error(ec);
    }
  }

  // Windows may not set an error code on failure.
  if (result == socket_error_retval && !ec)
    ec = asio::error::invalid_argument;

#if defined(UNDER_CE)
  if (result != socket_error_retval)
    clear_error(ec);
#endif

  return result == socket_error_retval ? -1 : 1;
#else // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  int result = error_wrapper(::inet_pton(af, src, dest), ec);
  if (result <= 0 && !ec)
    ec = asio::error::invalid_argument;
  if (result > 0 && af == AF_INET6 && scope_id)
  {
    using namespace std; // For strchr and atoi.
    *scope_id = 0;
    if (const char* if_name = strchr(src, '%'))
    {
      in6_addr_type* ipv6_address = static_cast<in6_addr_type*>(dest);
      bool is_link_local = IN6_IS_ADDR_LINKLOCAL(ipv6_address);
      if (is_link_local)
        *scope_id = if_nametoindex(if_name + 1);
      if (*scope_id == 0)
        *scope_id = atoi(if_name + 1);
    }
  }
  return result;
#endif // defined(BOOST_WINDOWS) || defined(__CYGWIN__)
}

inline int gethostname(char* name, int namelen, asio::error_code& ec)
{
  clear_error(ec);
  int result = error_wrapper(::gethostname(name, namelen), ec);
#if defined(BOOST_WINDOWS) && defined(UNDER_CE)
  if (result == 0)
    clear_error(ec);
#endif
  return result;
}

#if defined(BOOST_WINDOWS) || defined(__CYGWIN__) \
  || defined(__MACH__) && defined(__APPLE__)

// The following functions are only needed for emulation of getaddrinfo and
// getnameinfo.

inline asio::error_code translate_netdb_error(int error)
{
  switch (error)
  {
  case 0:
    return asio::error_code();
  case HOST_NOT_FOUND:
    return asio::error::host_not_found;
  case TRY_AGAIN:
    return asio::error::host_not_found_try_again;
  case NO_RECOVERY:
    return asio::error::no_recovery;
  case NO_DATA:
    return asio::error::no_data;
  default:
    BOOST_ASSERT(false);
    return asio::error::invalid_argument;
  }
}

inline hostent* gethostbyaddr(const char* addr, int length, int af,
    hostent* result, char* buffer, int buflength, asio::error_code& ec)
{
  clear_error(ec);
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  (void)(buffer);
  (void)(buflength);
  hostent* retval = error_wrapper(::gethostbyaddr(addr, length, af), ec);
  if (!retval)
    return 0;
# if defined(UNDER_CE)
  clear_error(ec);
# endif
  *result = *retval;
  return retval;
#elif defined(__sun) || defined(__QNX__)
  int error = 0;
  hostent* retval = error_wrapper(::gethostbyaddr_r(addr, length, af, result,
        buffer, buflength, &error), ec);
  if (error)
    ec = translate_netdb_error(error);
  return retval;
#elif defined(__MACH__) && defined(__APPLE__)
  (void)(buffer);
  (void)(buflength);
  int error = 0;
  hostent* retval = error_wrapper(::getipnodebyaddr(
        addr, length, af, &error), ec);
  if (error)
    ec = translate_netdb_error(error);
  if (!retval)
    return 0;
  *result = *retval;
  return retval;
#else
  hostent* retval = 0;
  int error = 0;
  error_wrapper(::gethostbyaddr_r(addr, length, af, result, buffer,
        buflength, &retval, &error), ec);
  if (error)
    ec = translate_netdb_error(error);
  return retval;
#endif
}

inline hostent* gethostbyname(const char* name, int af, struct hostent* result,
    char* buffer, int buflength, int ai_flags, asio::error_code& ec)
{
  clear_error(ec);
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)