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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]]
- From: Corinna Vinschen <corinna-cygwin at cygwin dot com>
- To: cygwin at cygwin dot com, cygwin-xfree at cygwin dot com
- Date: Wed, 12 Aug 2009 17:35:11 +0200
- 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]]
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- Reply-to: cygwin at cygwin dot com, cygwin-xfree at cygwin dot com
On Aug 12 16:20, Jon TURNEY wrote:
> On 12/08/2009 14:59, Corinna Vinschen wrote:
>> 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 . 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...
>>>>  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!
> Oh, I meant to say "A couple of small programs shamelessly copied from
> UNIX Network Programming". So don't thank me, thank W. Richard Stevens
I already thanked W. Richard Stevens in Cygwin's sources. He was *the*
network guy for me. His books and the source codes are invaluable.
I have applied a patch to accept(), btw. This should now work in the
given scenario. It occured to me that the returned value is incorrect
for AF_UNIX/AF_LOCAL sockets, but that was always the case and it's not
a regression. Usually the peer address of an AF_UNIX socket is not of
interest anyway. I added that to my TODO list and probably fix that in
a later release.
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Problem reports: http://cygwin.com/problems.html
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