Boost Asio message_flags

I encountered the same problem and my solution was to use overload that doesnt take message_flags parameter (http://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/reference/basic_datagram_socket/send_to/overload1.html ).

Downside is that if you want error code error reporting you cant use it(overload uses exception, and doesnt take ec param)

This param is forwarded to system call. For instance in Windows it is forwarded directly to WSASend. The meaning of param should be checked in OS docs: WSASend for Windows otherwise recvmsg.

I searched for a while and finally tried to look in Boost's source code. I found this in socket_base.hpp:

  /// Bitmask type for flags that can be passed to send and receive operations.
  typedef int message_flags;

  #if defined(GENERATING_DOCUMENTATION)
  /// Peek at incoming data without removing it from the input queue.
  static const int message_peek = implementation_defined;

  /// Process out-of-band data.
  static const int message_out_of_band = implementation_defined;

  /// Specify that the data should not be subject to routing.
  static const int message_do_not_route = implementation_defined;

  /// Specifies that the data marks the end of a record.
  static const int message_end_of_record = implementation_defined;
  #else
  BOOST_ASIO_STATIC_CONSTANT(int,
      message_peek = BOOST_ASIO_OS_DEF(MSG_PEEK));
  BOOST_ASIO_STATIC_CONSTANT(int,
      message_out_of_band = BOOST_ASIO_OS_DEF(MSG_OOB));
  BOOST_ASIO_STATIC_CONSTANT(int,
      message_do_not_route = BOOST_ASIO_OS_DEF(MSG_DONTROUTE));
  BOOST_ASIO_STATIC_CONSTANT(int,
      message_end_of_record = BOOST_ASIO_OS_DEF(MSG_EOR));
  #endif

Based on this, it looks like message_peek, message_out_of_band, and message_do_not_route are the possible values. I'm going to give these a try and see if I can get them to work.