Bird 1.6.3 strange hangup

[Ondrej Zajicek]

On Sun, Jul 02, 2017 at 12:27:18PM +0300, Andrew wrote:
> Hi all.
> 
> Today I saw strange bird hangup, which results in OSPF failure in areas
> where router is. BIRD works as OSPF + BGP. All returns to work state after
> bird was killed by SIGKILL and started again.
> 
> Here's strange logs records:
> 
> Jul  2 11:33:46 gw2 bird: I/O loop cycle took 7016 ms for 35 events
> Jul  2 11:33:57 gw2 bird: I/O loop cycle took 7208 ms for 58 events
> Jul  2 11:34:06 gw2 bird: I/O loop cycle took 5829 ms for 31 events

This seems like related to a problem. Do you have this messages in log
during normal operation? Esp. since 11:36:03, it locked for 38 s,
enough to timeout OSPF neighbors:

> Jul  2 11:36:03 gw2 bird: I/O loop cycle took 37685 ms for 22 events

Was BIRD at least partially interactive during hangup? Did it run with
100 % CPU load.

> Jul  2 11:41:49 gw2 bird: filters, line 47: AS path expected
> Jul  2 11:41:49 gw2 bird: filters, line 47: AS path expected
> Jul  2 11:41:49 gw2 bird: filters, line 47: AS path expected
> Jul  2 11:41:49 gw2 bird: filters, line 47: AS path expected
> Jul  2 11:41:49 gw2 bird: filters, line 47: AS path expected
> Jul  2 11:41:49 gw2 bird: ...
> 
> 
> There's filter config where error message happens:
> 
> function rt_client(int asn; prefix set nets)
> {
>         return (net ~ nets &&
>                 (bgp_path.first = asn || bgp_path ~ [= my_as asn * =]) &&
>                 bgp_path.last = asn);
> }

You could avoid that 'AS path expected' error msg by checking whether the
attribute is defined:

         return (net ~ nets &&
                 defined(bgp_path) &&
                 (bgp_path.first = asn || bgp_path ~ [= my_as asn * =]) &&
                 bgp_path.last = asn);


> After restart - all seems to be OK, except periodical messages 'Kernel
> dropped some netlink messages, will resync on next scan.' in log.
> 
> 
> What was happened? Bad BGP packets? Or some bug in bird?

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."