Re: route(8) and old messages

[Roy Marples <roy%marples.name@localhost>]

On 16/08/2018 13:08, Christos Zoulas wrote:
> I think that it is time to re-think how the routing socket works. Having
> each program and the kernel deal with sending and receing all versions of
> all messages is wasteful and painful to maintain. In the short term we
> should fix things to use a message filter to indicate interest on the
> message types they are interested, but the question is what to do in
> the long term...

We already have a message filter.
Here's the route(4) snippet:

     A process can specify which route message types it's interested in by
     passing an array of route messsage types to the setsockopt(2) call 
with
     the RO_MSGFILTER option at the PF_ROUTE level.  For example, to 
only get
     specific messages:

           unsigned char rtfilter[] = { RTM_IFINFO, RTM_IFANNOUNCE };

           if (setsockopt(routefd, PF_ROUTE, RO_MSGFILTER,
               &rtfilter, (socklen_t)sizeof(rtfilter)) == -1)
                   err(1, "setsockopt(RO_MSGFILTER)");

I think I've patched all the programs in base to use this already, 
including src/external.
So the only pain is really maintaining the backwards compatible stuff in 
the kernel which we're kinda bound to do as part of NetBSD anyway.

The exception to this is route(8) as kre rightfully pointed out we need 
to use it to verify the old messages are sent so filtering probably 
doesn't apply. I'm thinking about adding support to route(8) to decode 
the old messages as well, but not for SMALL binaries.

If there is anything better we can do long term, I'm sure out of ideas 
right now.

Roy