From owner-freebsd-net@FreeBSD.ORG  Thu Jan  8 14:15:45 2015
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id 5DADFBA2
 for <freebsd-net@freebsd.org>; Thu,  8 Jan 2015 14:15:45 +0000 (UTC)
Received: from smtp2.informatik.tu-muenchen.de
 (mail-out2.informatik.tu-muenchen.de [131.159.0.36])
 (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 1C9986B4
 for <freebsd-net@freebsd.org>; Thu,  8 Jan 2015 14:15:44 +0000 (UTC)
Received: from [131.159.50.43] (homer.sec.in.tum.de [131.159.50.43])
 by services.sec.in.tum.de (Postfix) with ESMTPSA id 80F6710110D41;
 Thu,  8 Jan 2015 15:08:12 +0100 (CET)
Message-ID: <54AE8F6D.8010900@sec.in.tum.de>
Date: Thu, 08 Jan 2015 15:08:45 +0100
From: Julian Kirsch <kirschju@sec.in.tum.de>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
 rv:31.0) Gecko/20100101 Icedove/31.3.0
MIME-Version: 1.0
To: freebsd-net@freebsd.org
Subject: Re: How to get the IP and TCP fields in mbuf
References: <BY1PR0301MB0902D447750F5497F5F016A6BB470@BY1PR0301MB0902.namprd03.prod.outlook.com>
In-Reply-To: <BY1PR0301MB0902D447750F5497F5F016A6BB470@BY1PR0301MB0902.namprd03.prod.outlook.com>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 8bit
Cc: weh@microsoft.com
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.18-1
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 08 Jan 2015 14:15:45 -0000

Hi Wei,

Are you looking for something like this?

+	struct ip *ip = mtod(m, struct ip *);

m is a struct mbuf *. You cann look into my knock-patch for FreeBSD [0]
for further examples.

Best,
Julian

[0] https://gnunet.org/knock

On 08.01.2015 14:18, Wei Hu wrote:
> Hi,
> 
> I am wondering if there is existing macros in the FreeBSD kernel to extract to get to the point of the IP and TCP head in a given mbuf.
> 
> Thanks,
> Wei
> 
> 
> _______________________________________________
> freebsd-net@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
> 


-- 
Julian Kirsch
Chair for IT-Security (I20)
Department of Computer Science, Technische Universität München
Boltzmannstrasse 3, D-85748 Garching bei München
Phone: +49-89-289-18587
Room: 01.08.53