BFD neighbor reload issue

[Winston Chen]

Hi,


I am using BFD neighbor to config BFD sessions statically. I found that 
if I add/remove BFD neighbors in bird.conf  and ask bird to reload with 
HUP signal, bird cannot reload the configuration correctly.

Here is the BFD config I used to test. If I start bird with this 
configuration, then comment one of the neighbors and send HUP with kill 
to bird, bird simply says session reconfigured without remove the 
commented neighbor.

protocol bfd {
interface "*" {
         passive;
};

neighbor 172.17.0.2;
neighbor 172.17.0.3;
}

After digging into the code, I found that it looks like there is a bug 
in function bfd_reconfigure_neighbors. It loops to check neighbor in old 
and new configuration. There is a return in the block if 
(bfd_same_neighbor(nn, on)). If there is  neighbor existing in both new 
and old, reconfiguration might be skipped.

I tried to modify the code to make it work. And the attached patch is 
the one I got. Hopefully this is the proper way to solve the issue.


Regards.

Chen.

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