2009/8/5 David Miller [off-list ref]:

I think we really cannot change behavior here.  If the user specifies
"0" in ipi_ifindex we must respect that in ipc->oif.  This is an
override, and the ability to override is the very purpose of this
control message.

Even GLIBC makes use of that case of specifying "0" in ipi_ifindex.
We must respect it.

I'm not applying any of these patches, sorry.

If you treat ipi_ifindex as an override, do you want to do that in
ipi6_ifindex as well? Also, CAP_NET_RAW check for SO_BINDTODEVICE
becomes meaningless in this case.

I did not find the usage of ipi_ifindex in glibc. It would be great if
you can give me some pointers. Thanks for your help.

Chia-chi