Hi,
In 2.4.0, ip_finsih output is listed as: static inline
int ip_finish_output2(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct hh_cache *hh = dst->hh;
#ifdef CONFIG_NETFILTER_DEBUG
nf_debug_ip_finish_output2(skb);
#endif /*CONFIG_NETFILTER_DEBUG*/
if (hh) {
read_lock_bh(&hh->hh_lock);
memcpy(skb->data - 16,
hh->hh_data,16);
read_unlock_bh(&hh->hh_lock);
skb_push(skb, hh->hh_len);
return hh->hh_output(skb);
} else if (dst->neighbour)
return dst->neighbour->output(skb);
printk(KERN_DEBUG "khm\n");
kfree_skb(skb);
return -EINVAL;
}
I guess its supposed to mean that if the hardware
header is cached for the dst_entry, then copy 16 bytes
of the header into the skb starting at skb->data - 16.
So are we assuming that the header length is always
16? (magic number)
And after that, we push skb->data back by hh->hh_len.
Does this value equal 16?
Either the data size used in skb_push should be 16,
or the memcpy should use hh_len.
Whats the purpose of doing it differently?
TIA
Akshay
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