Hello,
On Sat, 28 Jun 2003, Ben Greear wrote:
> > - check for UP state (is it needed? return ENETDOWN?)
> > - check if target IP is local and select "lo" instead of oif
First, here is what I mean (not compiled):
- ignore matching of the oif key for local destinations
- return ENETDOWN when the specified out_dev is down
Dave, Alexey, can you judge on these issues because
they are not fatal corner cases and can be ignored.
--- v2.4.21/linux/net/ipv4/fib_semantics.c.orig Sat Jun 14 08:42:55 2003
+++ v2.4.21/linux/net/ipv4/fib_semantics.c Sun Jun 29 09:28:10 2003
@@ -603,7 +603,9 @@
for_nexthops(fi) {
if (nh->nh_flags&RTNH_F_DEAD)
continue;
- if (!key->oif || key->oif == nh->nh_oif)
+ if (!key->oif ||
+ key->oif == nh->nh_oif ||
+ nh->nh_scope == RT_SCOPE_NOWHERE)
break;
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
--- v2.4.21/linux/net/ipv4/route.c.orig Sat Jun 14 08:42:55 2003
+++ v2.4.21/linux/net/ipv4/route.c Sun Jun 29 09:16:03 2003
@@ -1793,6 +1793,9 @@
dev_put(dev_out);
goto out; /* Wrong error code */
}
+ err = -ENETDOWN;
+ if (!(dev_out->flags&IFF_UP))
+ goto out;
if (LOCAL_MCAST(oldkey->dst) || oldkey->dst == 0xFFFFFFFF) {
if (!key.src)
> Well, why should it try to route locally in this case (I'm assuming that
> by using 'lo' it will not try to send on the external link)
No, it does not use "lo", "lo" replaces "dev" only if we get
RTN_LOCAL result. But "to local_IP dev different_device"
can escape from our host because we can not find route and thus we
can not override out_dev with lo.
> Why not instead make it send to the router for that source-ip, if it is
> configured. If it is not configured, then I think arping is the best that
What we have is that app uses BINDTODEVICE to send
packet with saddr=some_IP daddr=any_valid_local_IP. This is
confusing but I do not see any harm. But I think route request
"to local_IP" deserves "lo" result no matter the oif key.
> can be expected, as the behaviour becomes quite undefined and we really
> have 'no route to host'.
The only reason can be to avoid confusions and to
make it symmetric with the source validation check. And yes,
this patch breaks your tests.
> My send-to-self patch that I have been using is attached. I also have some
> other
> patches for mac-vlans and packet-gen applied, but I don't believe these will
> have any
> impact on the behaviour we have been discussing.
I don't see anything in your patch that can disturb these
tests. The kernel is helpful enough to send your ARP probe for
local_IP on the LAN :) When I tested the first time, you claimed
-I local_IP1 local_IP2 causes the problem but as we see, it is
caused from -I dev
> Thanks,
> Ben
Regards
--
Julian Anastasov <ja@xxxxxx>
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