rip_input

[Arun Anirudhan]

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.
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);


-- 
With regards
Arun Anirudhan
MTech Student, NIT Calicut
9495983679