ospf ptp link sending unicast packets instead of multicast; peer address config not required

[Joakim Tjernlund]

On Thu, 2021-05-06 at 17:09 +0000, Senthil Kumar Nagappan wrote:
> Hi,
> 
> I did sent this message a week back but I could not see it in the mailing, moreover just now subscribed to this mailing list, so sending this again.
> 
> I’m seeing some issues with ospf adj over ptp numbered/unnumbered interface. 
> 
> 1. For p2p connections, ospf should be sending only multicast packets to allospfrouters, but I see its sending to unicast address.
> (From RFC “On physical point-to-point networks, the IP destination is always set to the address AllSPFRouters”)
> 2. For ptp over unnumbered interface, bird requires peer address configuration which is not required from the ospf perspective. Because bird is using peer address and sending
> unicast packets, bird cannot form multiple ospf adj over ptp unnumbered interface between 2 endpoints using same peer address.
> Made some quick changes and have attached the patch that addresses the issues. Relaxed the source ip address validation for ptp link in packet.c for now. More validation can be
> added to make it complete.
> 
> Thanks and Regards,
> Senthil
> 

Hi Senthil

I took a closer look at your hack/patch ...
You seem to miss correcting a few ospf_send_to() call sites. I wonder in its not better to
override the dst addr inside ospf_send_to() instead?

Also, the mcast changes in packet.c looks incomplete, there is IPv6 and and area == 0 further down
to consider.

 Jocke