Bug: Cannot export static route on FreeBSD running bird 3.1

[David Petera]

Hello Yuri,

that really looks like an oversight on our side.

Right now we are running in a somewhat "holiday" mode, but I will put it 
in our backlog.
We will get to it as soon as we can.

Thanks a lot for the thorough report and have a nice week!
David

David Petera (he/him) | BIRD Tech Support | CZ.NIC, z.s.p.o.

On 8/10/25 20:25, Yuri Honegger via Bird-users wrote:
> I'm running the following configuration that simply exports a static route to the kernel on FreeBSD with bird v3.1:
>
> protocol device {
>      scan time 60;
> }
>
> protocol static {
> ipv4;
>      route 10.119.0.0/24 via "en6";
> }
>
> protocol kernel {
> 	ipv4 {
> 	    export all;
> 	};
> }
>
> For some reason, this doesn't export the route. Looking at the bird logs, for some reason the kernel protocol seems to reject the route:
>
> bird: 2025-08-10 20:08:30.783 [0001] <TRACE> kernel1: Pruning table master4
> bird: 2025-08-10 20:08:30.783 [0001] <TRACE> kernel1.ipv4: route refresh end: rr 1 set 1 valid 1 pruning 0 pruned 0
> bird: 2025-08-10 20:08:30.783 [0001] <TRACE> kernel1.ipv4: Feeding 10.119.0.0/24
> bird: 2025-08-10 20:08:30.784 [0001] <TRACE> kernel1.ipv4 < rejected by protocol 10.119.0.0/24 ptr 000000016d18ec30 (0) src 0L 3G 0S id 1 unicast
> bird: 2025-08-10 20:08:30.784 [0002] <TRACE> kernel1.ipv4: table prune after refresh begin: rr 1 set 1 valid 1 pruning 1 pruned 0
> bird: 2025-08-10 20:08:30.784 [0002] <TRACE> kernel1.ipv4: table prune after refresh end: rr 0 set 1 valid 1 pruning 1 pruned 1
> bird: 2025-08-10 20:08:30.784 [0001] <TRACE> kernel1.ipv4 < idempotent withdraw (filtered on export) 10.119.0.0/24 ptr 0000000102e58050 (0) src 0L 3G 0S id 1 unicast
> bird: 2025-08-10 20:08:30.784 [0001] <TRACE> kernel1.ipv4: Export state changed from PARTIAL to READY
> bird: 2025-08-10 20:08:30.784 [0001] <TRACE> kernel1.ipv4: Fed up
> bird: 2025-08-10 20:08:30.784 [0001] <TRACE> kernel1: Table master4 pruned
> bird: 2025-08-10 20:08:30.784 [0001] <TRACE> kernel1.ipv4: Export drained
>
> During a debuggin session, I've traced it to the following lines things:
> It seems to be rejected in nest/rt-table.c, function export_filter because p->preexport returns -1
> https://gitlab.nic.cz/labs/bird/-/blob/stable-v3.1/nest/rt-table.c?ref_type=heads#L1077
>
> Tracing that further, the actual reason it does get rejected seems to come from here in krt_capable:
> https://gitlab.nic.cz/labs/bird/-/blob/stable-v3.1/sysdep/bsd/krt-sock.c?ref_type=heads#L177
>
> A debugging printf showed !NEXTHOP_ONE(nh) is always false. As far as I understand, NEXTHOP_ONE returns true if there is just one nexthop, so !NEXTHOP_ONE(nh) effectively demands multiple nexthops.
> This contradicts the comment that no multipath is supported. Furthermore, looking at the last commit touching that line, the condition used to be !a->nh.next, which reads
> to me as checking that there is just one nexthop. I suspect the condition there is probably wrong and should say NEXTHOP_ONE(nh) without negation?
> Changing that made bird export the route just fine in a quick test.
>
> Does that make any sense?
>
> Yuri