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Date: Tue, 15 Dec 2009 18:10:51 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: SO_REUSEADDR and windows enhanced socket security
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On Dec 15 18:48, yesin wrote:
> looks like a problem with SO_REUSEADDR exists in CYGWIN for all
> windows with support for "Enhanced socket security" (see
> http://msdn.microsoft.com/en-us/library/ms740621(VS.85).aspx <http://www.google.com/url?sa=D&q=http://msdn.microsoft.com/en-us/library/ms740621%28VS.85%29.aspx&usg=AFQjCNF9bXOmPTwYjiP37Xdq2xRAYNXfWg>)
> 
> 
> i'am trying to start multimple simultaneous UDP listeners for a
> multicast packets on a single machine (reuse same address and port
> with SO_REUSEADDR)
> [...]
> with cygwin environment i can't run multiple listerers... bind error:
> Address already in use!

Thanks for the report and especially thanks for the testcase.  There
is code in Cygwin which skips calls to setsockopt(SO_REUSEADDR) on
systems supporting enhanced socket security.  That's necessary to
emulate socket re-binding behaviour more closely to POSIX behaviour.
The problem was that this should have been only called for TCP sockets
but Cygwin accidentally called it for UDP sockets as well.  I fixed
that in CVS.


Thanks again,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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