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Re: [Fwd: [ANNOUNCE] Layer-7 Filter for Linux QoS]

To: Ethan Sommer <sommere@xxxxxxxxxxx>
Subject: Re: [Fwd: [ANNOUNCE] Layer-7 Filter for Linux QoS]
From: Philippe Biondi <biondi@xxxxxxxxxxxxxxxxxx>
Date: Thu, 22 May 2003 01:11:35 +0200 (CEST)
Cc: Jamal Hadi <hadi@xxxxxxxxxxxxxxxx>, Martin Josefsson <gandalf@xxxxxxxxxxxxxx>, "David S. Miller" <davem@xxxxxxxxxx>, <linux-net@xxxxxxxxxxxxxxx>, <netdev@xxxxxxxxxxx>
In-reply-to: <3ECB9F6A.20004@xxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
On Wed, 21 May 2003, Ethan Sommer wrote:

> Philippe Biondi wrote:
>
> >regexp support was planned but not done yet. (if someone know where I can
> >download more free time !).
> >
> >The implementation should not be that hard, once you have the compiler to
> >transform the string describing the regexp to an automaton.
> >
> >Note that to respect the framework, you have to deal with multiple
> >patterns (should not be that hard). If you have pat1 and pat2, searching
> >for (pat1|pat2) is not sufficient because for each match, you have to
> >point which pattern matched.
> >
> >
>
> We actually planned on doing that initially. You should note that if you
> want to generate one automaton for multiple patterns, that is not a
> regular language (and thus can not be represented by a FA or DFA.)  You
> will have to try matching against the first pattern, then the next and
> so on.

If P and Q are regexps, P|Q is a regexp, so you do can.
So detection is clearly not a problem. But to fit in the libqsearch model,
you have to know which of the parterns matched. This is theorically
possible, but need a bit of work in comparison with using an
off-the-shelf regexp compiler on (Pat1|Pat2|..|Patn).



-- 
Philippe Biondi <biondi@ cartel-securite.fr> Cartel Sécurité
Security Consultant/R&D                      http://www.cartel-securite.fr
Phone: +33 1 44 06 97 94                     Fax: +33 1 44 06 97 99
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