X-Recipient: archive-cygwin@delorie.com X-SWARE-Spam-Status: No, hits=-1.3 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Message-ID: <4A82F7FB.3000609@sipxx.com> Date: Wed, 12 Aug 2009 13:12:27 -0400 From: cygwin User-Agent: Thunderbird 2.0.0.22 (Windows/20090605) MIME-Version: 1.0 To: cygwin@cygwin.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]] References: <4A78A511.8020109@sipxx.com> <4A803D7C.6070800@dronecode.org.uk> <4A825EE5.5020709@sipxx.com> <4A82BB83.1090908@dronecode.org.uk> <4A82C835.9030504@dronecode.org.uk> In-Reply-To: <4A82C835.9030504@dronecode.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com The opengroup man page indeed specifies the address to be truncated if the storage size is too small. I wonder, however, what kind of sense that makes. Of what use would the truncated address be? This might also require applications to verify the integrity of the data returned even if accept() returns successfully. However, Linux also has accept() returning successfully in this case. For compatibility, the Cygwin implementation should probably be faithful to the *NIX behavior and not the Windows practice, since the primary idea of Cygwin is to be a portability layer for *NIX apps. 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. > ------------------------------------------------------------------------ > > -- > 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 -- 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