Re: sk_buff extraction problem

[Thomas 'Dent' Mirlacher]

hi Will,

--snip/snip

> for no particular reason i choose dev.c and a function called 
> netif_rx to do this.
> 
> at the beginning of netif_rx() i added the lines:
> int this_cpu = smp_processor_id();
> ........
>         char *p;
>         int i;
>         
>                  //  p=   (char *) (skb->mac.ethernet);
>                     p=   (char *) (skb->h.uh);
> 
> then just before return softnet_data[this_cpu].cng_level;
> i added this:
> 
> for( i=0; i<8;i++){
>             printk(KERN_DEBUG"netif_rx() ->ethernet: %02x ",*(p+i));
>             }
> 
> it complies but as soon as i pass a packet through it the router 
> freezes up.
> 
> am i even on the rigth track?

you're on the right track if you want to freeze up your machine. :)

ok, here we go:

netif_rx is called from the driver, and at this point of skbs
livetime you can just be sure about the datalink layer beeing
decapsulated (called by the driver (e.g. eth_type_trans)).

so this means: you have a valid skb->mac.ras well as the skb->data
beeing a pointer to your network layer. - and that's about it ...
if you want to know about IP headers, you should hook into the network
subsystem at the IP layer (and there's already a nice NF_HOOK
- called NF_IP_LOCAL_IN)

anyhow - try to use the infrastructure which is already there.

	my $0.02

		tm
-- 
in some way i do, and in some way i don't.