Start an asynchronous receive.

template<
    typename MutableBufferSequence,
    typename ReadHandler>
void-or-deduced async_receive(
    const MutableBufferSequence & buffers,
    ReadHandler handler);
  » more...

template<
    typename MutableBufferSequence,
    typename ReadHandler>
void-or-deduced async_receive(
    const MutableBufferSequence & buffers,
    socket_base::message_flags flags,
    ReadHandler handler);
  » more...