X-Recipient: archive-cygwin AT delorie DOT com
X-Spam-Check-By: sourceware.org
Date: Wed, 12 Aug 2009 15:59:41 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin-xfree AT cygwin DOT com, cygwin AT cygwin DOT com
Subject: Re: [1.7] IPv6 accept() fails if address_len is < 	sizeof(sockaddr_in6)  [was Re: PATCH 	/usr/include/X11/Xtrans/Xtranssock.c   [WAS: Re: xhost  package 	not compiled for IPv6]]
Message-ID: <20090812135941.GD13438@calimero.vinschen.de>
Reply-To: cygwin-xfree AT cygwin DOT com
Mail-Followup-To: cygwin-xfree AT cygwin DOT com, cygwin AT cygwin DOT com
References: <4A78A511 DOT 8020109 AT sipxx DOT com> <4A803D7C DOT 6070800 AT dronecode DOT org DOT uk> <4A825EE5 DOT 5020709 AT sipxx DOT com> <4A82BB83 DOT 1090908 AT dronecode DOT org DOT uk> <4A82C835 DOT 9030504 AT dronecode DOT org DOT uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4A82C835.9030504@dronecode.org.uk>
User-Agent: Mutt/1.5.19 (2009-02-20)
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
Precedence: bulk
List-Id: <cygwin.cygwin.com>
List-Unsubscribe: <mailto:cygwin-unsubscribe-archive-cygwin=delorie DOT com AT cygwin DOT com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

On Aug 12 14:48, Jon TURNEY wrote:
> On 12/08/2009 13:54, Jon TURNEY wrote:
>> Hmmm... but if it's really the size of the sockname argument which is
>> causing the accept() to fail, this would be a bug in cygwin's accept()
>> implementation, as it's supposed to truncate the data written to the
>> sockname, rather than fail if it won't fit [1]. If that actually is the
>> case, since we don't actually use the peer address here, the code as
>> stands is correct (if a little odd).
>>
>> I suppose I need to write a small test case to look at this...
>>
>> [1] http://www.opengroup.org/onlinepubs/009695399/functions/accept.html
>
> A couple of small programs which hopefully demonstrate this problem.
>
> (As is, the connection fails, but uncommenting the alternate definition 
> of cliaddr in listener.c allows it to work)
>
> I'd hazard a guess that perhaps this is because the underlying winsock  
> accept() doesn't have this truncate behaviour and considers a too-small  
> address_len an error.

Thanks for the testcase!  This confirms what I wrote about WinSock in
http://cygwin.com/ml/cygwin-xfree/2009-08/msg00029.html

Now for the patch to workaround that problem...


Corinna

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

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple