On Tue, 08 Jul 2014 15:12:10 -0700 (PDT)
David Miller <da...@davemloft.net> wrote:
> From: Dmitry Popov <ixaph...@qrator.net>
> Date: Sat, 5 Jul 2014 02:26:37 +0400
>
> > @@ -205,6 +207,8 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net
> > *itn,
> >
> > hlist_for_each_entry_rcu(t, head, hash_node) {
> > if (t->parms.i_key != key ||
> > + t->parms.iph.saddr != 0 ||
> > + t->parms.iph.daddr != 0 ||
> > !(t->dev->flags & IFF_UP))
> > continue;
> >
>
> I don't really understand the logic of these tests.
>
> Usually the canonical way to test these kinds of things is:
>
> if (parms->saddr && parms->saddr != saddr)
> goto no_match;
>
> But you are signalling a non-match any time the address is not a
> wildcard.
>
> Why?
Because that's exactly what I want: to skip any non-wildcard tunnels.
How I see ip_tunnel_lookup logic:
1) try to find exact match (and if found return this tunnel):
tunnel.saddr == iph.daddr && tunnel.daddr == iph.saddr && key_matched()
2) try to find matched (local) wildcard tunnel:
tunnel.saddr == any && tunnel.daddr == iph.saddr && key_matched()
3) try to find matched (remote) wildcard tunnel:
tunnel.saddr == iph.daddr && tunnel.daddr == any && key_matched()
(there is also a test for multicast tunnel, but let's skip it for simplicity)
4) try to find matched (full) wildcard tunnel:
tunnel.saddr == any && tunnel.daddr == any && key_matched()
5) if nothing found return default tunnel.
According to this logic, in 4th loop (the one you quoted) we have to test that
tunnel.daddr == any && tunnel.saddr == any. In my opinion those two new lines
are the best way to achieve it.
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