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SubjectRe: Why is TCP checksum calc split between init & complete fns?
kuznet@ms2.inr.ac.ru wrote:

> > If I want to run a TCP checksum (pseudo header + TCP header + data)
> > independently of the current TCP code, should I just do:
> >
> > tcp_v4_check( skb->h.th,skb->len,skb->nh.iph->saddr,skb->nh.iph->daddr,
> > csum_partial((char *)skb->h.th, skb->len, 0))
> > );
>
> Yes.

OK, thanks. If anyone out there knows, I'd still like to find out
why this is normally only done for TCP packets <= 68 bytes.


> > or do I need to call tcp_v4_checksum_init followed by tcp_checksum_complete?
>
> In no curcumstances. This function modify skb head.

Which function mods the head? As far as I can see, for big packets the
"init" function puts the pseudo-header checksum in skb->csum, while the
"complete" function (include/net/tcp.h not net/ipv4/tcp.c -- my apologies)
checks the rest of the packet. Why the split?

Mark
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