[Users] Problems with reverse DNS resolving in comp_ip

[Andreas Sikkema]

Hi,

Today we had an issue on one of our openser machines. Some CPEs that
were trying to register came from an IP address that for some reason
would not (or very slowly, or both) resolve to a DNS name.

Therefore openser was very slow to respond to any incoming SIP message,
resulting in loads of unreachable customers. About one third of the
registration attempts was succeeding and I think hardly any call
attempts succeeded.

What lead us to the DNS problem was that we increased the loglevel from
3 (our normal loglevel) to 7 and we noticed lots of "comp_ip: could not
rev_resolve ip address xxx.xxx.xxx.xxx" messages.

Why is the function eval_elem() in route.c calling comp_ip which in turn
wants to resolve an ip address? Is it really necessary?

Naturally I will try to find out why the dns resolver was taking so
long, but I'm having trouble finding out from the source why resolving
an ip address is necessary.

Thanks!

-- 
Andreas (who's very sleepy, it took quite a while to figure this one
out)