[Boost-bugs] [Boost C++ Libraries] #4170: Error using null_buffers in async_send_to in Windows

Subject: [Boost-bugs] [Boost C++ Libraries] #4170: Error using null_buffers in async_send_to in Windows
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-04-29 22:45:15

#4170: Error using null_buffers in async_send_to in Windows
-------------------------------------+--------------------------------------
 Reporter:  nythil@…                 |       Owner:  chris_kohlhoff
     Type:  Bugs                     |      Status:  new           
Milestone:  Boost 1.43.0             |   Component:  asio          
  Version:  Boost Development Trunk  |    Severity:  Problem       
 Keywords:                           |  
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 While exploring the boost.asio library I came across a bug caused by a
 typo in one of the header files. When async_send_to is invoked on an UDP
 socket with null_buffers, the following sequence of calls takes place:
  1. {{{basic_datagram_socket->async_send_to(const ConstBufferSequence&
 buffers, const endpoint_type& destination, WriteHandler handler)}}}
  2. {{{datagram_socket_service->async_send_to(implementation_type& impl,
 const ConstBufferSequence& buffers, const endpoint_type& destination,
 socket_base::message_flags flags, WriteHandler handler)}}}
  3. {{{win_iocp_socket_service->async_send_to(implementation_type& impl,
 const ConstBufferSequence& buffers, const endpoint_type& destination,
 socket_base::message_flags flags, Handler handler)}}}

 The problem is, the 3rd function is the generic version of async_send_to()
 which expects a valid buffer. Passing null_buffers causes an error.

 There is also a specialization of async_send_to() for the null_buffers
 case. Unfortunately, it's never called, because in the declaration some
 arguments are out of place. The declaration is:
 {{{async_send_to(implementation_type& impl, const null_buffers&,
 socket_base::message_flags, const endpoint_type&, Handler handler)}}}.
 Compared to the generic version, the {{{flags}}} and {{{destination}}}
 arguments are swapped. After correcting the order of these two arguments,
 async_send_to() works as expected.

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/4170>
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