int getsockopt()

in demo_example/asio/asio/detail/impl/socket_ops.ipp [1946:2039]

• 72 lines of code
• 26 McCabe index (conditional complexity)

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

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

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

    *static_cast<int*>(optval) = (state & enable_connection_aborted) ? 1 : 0;
    ec.assign(0, ec.category());
    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"))
    {
      int tmp_optlen = static_cast<int>(*optlen);
      int result = gso(s, level, optname,
            reinterpret_cast<char*>(optval), &tmp_optlen);
      get_last_error(ec, result != 0);
      *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.assign(0, ec.category());
      }
      return result;
    }
  }
  ec = asio::error::fault;
  return socket_error_retval;
#elif defined(ASIO_WINDOWS) || defined(__CYGWIN__)
  int result = call_getsockopt(&msghdr::msg_namelen,
        s, level, optname, optval, optlen);
  get_last_error(ec, result != 0);
  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.assign(0, ec.category());
  }
  return result;
#else // defined(ASIO_WINDOWS) || defined(__CYGWIN__)
  int result = call_getsockopt(&msghdr::msg_namelen,
        s, level, optname, optval, optlen);
  get_last_error(ec, result != 0);
#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(ASIO_WINDOWS) || defined(__CYGWIN__)
}