From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philip Craig Subject: Re: libnl: Unmatched NL_ACT_DEL and NL_ACT_CHANGE Date: Tue, 07 Jul 2009 15:29:42 +1000 Message-ID: <4A52DD46.5090501@snapgear.com> References: <200907051144.51967.volker@openbios.org> <4A51E024.8090402@trash.net> <200907061417.41282.volker@openbios.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: Patrick McHardy , netfilter-devel@vger.kernel.org To: Volker Poplawski Return-path: Received: from rex.securecomputing.com ([203.24.151.4]:57124 "EHLO cyberguard.com.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751824AbZGGF3k (ORCPT ); Tue, 7 Jul 2009 01:29:40 -0400 In-Reply-To: <200907061417.41282.volker@openbios.org> Sender: netfilter-devel-owner@vger.kernel.org List-ID: Volker Poplawski wrote: > On Monday 06 July 2009 13:29:40 you wrote: >> Volker Poplawski wrote: >>> Hi all. >>> >>> Could s.o. please have a look at my (short) code at >>> http://pastie.org/534637 >>> >>> (maybe compile it with g++ -Wall test.c -o test -I ... -L ... -lnl >>> -lnl-genl - lnl-nf -lnl-route) >>> >>> What the code does is to listen to changes in the ct-table using libnl. >>> It keeps score of reported ctId in a lookup table. >>> >>> Problem is: I'm getting a lot of NL_ACT_CHANGE & NL_ACT_DEL without >>> having seen a matching NL_ACT_NEW. (Also there seems to be no initial >>> cache fill) >>> >>> kernel 2.6.27 (opensuse 11.1), libnl 2.0 (git master) >> I think I know whats happening - the ct objects don't define the >> attribute(s) distinguishing different entries, so cache_include() >> doesn't recognize them as new. >> >> Does this patch make any difference? Yes that improves it. We probably want to change libnl so that we can specify a set of optional attributes to compare, so that nl_object_identical does something like this: if ((a->ce_mask & req_attrs) != req_attrs || (b->ce_mask & req_attrs) != req_attrs) return 0; if ((a->ce_mask & opt_attrs) != (b->ce_mask & opt_attrs)) return 0; ... return !(ops->oo_compare(a, b, (req_attrs | a->ce_mask & opt_attrs), 0)); This would let it work on older kernels that don't include the id too. > Yes it does, NL_ACT_DEL , _CHANGE and _DEL are now matching -- for ct-entries > created after i made my call to nl_cache_mngr_add( ... "netfilter/ct"... ) > > However, i still don't get a NL_ACT_DEL on already existing connections > (CHANGE and DEL though) I assume you meant you don't get NL_ACT_NEW events for existing connections. That's just how libnl works in general. You can use nl_cache_get_first/nl_cache_get_next to populate your hashtable before you start polling.