From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pablo Neira Ayuso <pablo@netfilter.org>
Subject: Re: [conntrack-tools PATCH] tcp: use MSG_NOSIGNAL in sendto() to
 avoid SIGPIPE
Date: Sat, 29 Aug 2015 01:10:56 +0200
Message-ID: <20150828231056.GA593@salvia>
References: <20150826121400.14339.57368.stgit@r2d2.cica.es>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: netfilter-devel@vger.kernel.org
To: Arturo Borrero Gonzalez <aborrero@cica.es>
Return-path: <netfilter-devel-owner@vger.kernel.org>
Received: from mail.us.es ([193.147.175.20]:43104 "EHLO mail.us.es"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752645AbbH1XEd (ORCPT <rfc822;netfilter-devel@vger.kernel.org>);
	Fri, 28 Aug 2015 19:04:33 -0400
Content-Disposition: inline
In-Reply-To: <20150826121400.14339.57368.stgit@r2d2.cica.es>
Sender: netfilter-devel-owner@vger.kernel.org
List-ID: <netfilter-devel.vger.kernel.org>

On Wed, Aug 26, 2015 at 02:14:00PM +0200, Arturo Borrero Gonzalez wrote:
> From: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
> 
> When running a pair of conntrackd nodes, in NOTRACK/tcp sync mode, and one
> conntrackd instance is shut down this can happen:
> 
> [...]
> Program received signal SIGPIPE, Broken pipe.
> 0x00007ffff6ef99d3 in __sendto_nocancel () at ../sysdeps/unix/syscall-template.S:82
> (gdb) bt
> #0  0x00007ffff6ef99d3 in __sendto_nocancel () at ../sysdeps/unix/syscall-template.S:82
> #1  0x0000000000416744 in tcp_send (m=0x657470, data=0x656e90, size=1436) at tcp.c:304
> #2  0x0000000000416b8c in channel_tcp_send (channel=<optimized out>, data=<optimized out>, len=<optimized out>) at channel_tcp.c:47
> #3  0x00000000004159ac in channel_send (c=0x656e60, net=0x64b3a0) at channel.c:241
> #4  0x00000000004184ee in internal_bypass_ct_event_del (ct=<optimized out>, origin=<optimized out>) at internal_bypass.c:148
> #5  internal_bypass_ct_event_del (ct=0x654940, origin=6647440) at internal_bypass.c:139
> #6  0x00000000004103c2 in event_handler (nlh=0x7fffffffb330, type=NFCT_T_DESTROY, ct=0x654940, data=<optimized out>) at ctnl.c:198
> #7  0x00007ffff79c1afb in __callback (nlh=0x7fffffffb330, nfa=<optimized out>, data=0x654860) at callback.c:60
> #8  0x00007ffff71ab06f in nfnl_step (h=h@entry=0x658e50, nlh=nlh@entry=0x7fffffffb330) at libnfnetlink.c:1341
> #9  0x00007ffff71ab813 in nfnl_process (h=h@entry=0x658e50, buf=buf@entry=0x7fffffffb330 "\214", len=len@entry=140) at libnfnetlink.c:1386
> #10 0x00007ffff71abb86 in nfnl_catch (h=0x658e50) at libnfnetlink.c:1540
> #11 0x00007ffff79c2a2d in nfct_catch (h=<optimized out>) at api.c:1024
> #12 0x0000000000410570 in event_cb (data=<optimized out>) at ctnl.c:330
> #13 0x000000000040ddb4 in select_main_step (next_alarm=0x7fffffffd390) at fds.c:126
> #14 select_main_loop () at fds.c:147
> #15 0x0000000000409104 in main (argc=<optimized out>, argv=<optimized out>) at main.c:428
> [...]
> 
> >From sendto(2):
>  EPIPE  [...] the process will also receive a SIGPIPE unless MSG_NOSIGNAL is set

Hm, we're already ignoring SIGPIPE. I guess this has to be with your
gdb configuration?

https://sourceware.org/gdb/onlinedocs/gdb/Signals.html