From owner-freebsd-net@FreeBSD.ORG  Thu Oct 22 18:03:51 2009
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id ABD80106566B
	for <freebsd-net@freebsd.org>; Thu, 22 Oct 2009 18:03:51 +0000 (UTC)
	(envelope-from julian@elischer.org)
Received: from outS.internet-mail-service.net (rly2.mx.aerioconnect.net
	[216.240.35.226])
	by mx1.freebsd.org (Postfix) with ESMTP id 954938FC08
	for <freebsd-net@freebsd.org>; Thu, 22 Oct 2009 18:03:51 +0000 (UTC)
Received: from idiom.com (mx0.idiom.com [216.240.32.160])
	by out.internet-mail-service.net (Postfix) with ESMTP id 73D6EC9282;
	Thu, 22 Oct 2009 10:53:08 -0700 (PDT)
X-Client-Authorized: MaGic Cook1e
X-Client-Authorized: MaGic Cook1e
Received: from julian-mac.elischer.org
	(h-67-100-89-137.snfccasy.static.covad.net [67.100.89.137])
	by idiom.com (Postfix) with ESMTP id DEFFE2D6028;
	Thu, 22 Oct 2009 10:53:07 -0700 (PDT)
Message-ID: <4AE09C03.6050201@elischer.org>
Date: Thu, 22 Oct 2009 10:53:07 -0700
From: Julian Elischer <julian@elischer.org>
User-Agent: Thunderbird 2.0.0.23 (Macintosh/20090812)
MIME-Version: 1.0
To: Arun Anirudhan <arun.anirudhan@gmail.com>
References: <c668d9dd0910221019n3156db19j8b597d2d4ae728ec@mail.gmail.com>
In-Reply-To: <c668d9dd0910221019n3156db19j8b597d2d4ae728ec@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: freebsd-net@freebsd.org
Subject: Re: rip_input
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/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, 22 Oct 2009 18:03:51 -0000

Arun Anirudhan wrote:
> Hello
> I have just started programming in Kernel Level in FreeBSD.
> I'm trying to hook rip_input and extract the fields in IP header. I just
> tried to print the ip_len.
> This is the code, but its not getting printed.

what IS getting printed?

> Please help me...
> ---------------------------------
> 
> #include <sys/param.h>
> #include <sys/proc.h>
> #include <sys/module.h>
> #include <sys/kernel.h>
> #include <sys/systm.h>
> #include <sys/mbuf.h>
> #include <sys/protosw.h>
> 
> #include <netinet/in.h>
> #include <netinet/in_systm.h>
> #include <netinet/ip.h>
> #include <netinet/ip_icmp.h>
> #include <netinet/ip_var.h>
> 
> 
> extern struct protosw inetsw[];
> pr_input_t rip_input_hook;
> 
> void rip_input_hook(struct mbuf *m, int off)
> {
>         struct ip *icp;
>         int hlen=off;
>         int l;
>         //m->m_len-=hlen;
>         //m->m_data+=hlen;
> 
>         icp=mtod(m, struct ip *);
>         l=icp->ip_len;
> 
>         //m->m_len+=hlen;
>         //m->m_data-=hlen;
>         uprintf("%d.\n",l);
> }
> 
> static int
> load(struct module *module, int cmd, void *arg)
> {
>         int error = 0;
> switch (cmd) {
> case MOD_LOAD:
>                 inetsw[ip_protox[IPPROTO_RAW]].pr_input = rip_input_hook;
>                 break;
>         case MOD_UNLOAD:
>                 inetsw[ip_protox[IPPROTO_RAW]].pr_input = rip_input;
>                 break;
>         default:
>                 error = EOPNOTSUPP;
>                 break;
>         }
> return (error);
> }
> static moduledata_t rip_input_hook_mod = {
>         "rip_input_hook", load, NULL};
> DECLARE_MODULE(rip_input_hook,rip_input_hook_mod,SI_SUB_DRIVERS,SI_ORDER_MIDDLE);
> 
>