[Freeswitch-users] info about sofia sip dns cache and graylisting?

[Brian West]

can you get some logs, sofia loglevel all 9, and file a JIRA and attach the
logs and detailed info to the JIRA please.

Also verify which rev of FreeSWITCH you're running when filing the JIRA.

On Fri, May 8, 2015 at 9:34 AM, Michel Brabants <michel.brabants at gmail.com>
wrote:

> Hello all,
>
> we have a problem with a 1.4-version of Freeswitch that FS goes to 100%
> cpu. The problem has been traced to a dns-cache-problem. The dns-cache
> contains srv-records, which should have 2 a-records, but they have 100's of
> a-records, which are mostly the same (some with a different priority). This
> causes FS do to a lot of compares (to sort the records) and it goes to 100%
> cpu in the end.
> The priority almost never is the original priority, so I was thinking that
> the cache is maybe growing because of graylisting of entries, causing the
> priority to increase and the ttl to be reset.
>
> The code is however very difficult to follow as it is all event-based and
> part of big C-structs in sofia-sip. A bug in the gdb-debugger causing
> static variables to be almost unreadable makes life not much easier. The
> graylisting policy, as well as the dns cache policy is not really
> documented as far as I can find, so any info about this would be great.
>
> Anyway, my current thought is that the dns-cache is maybe growing, becuase
> the graylisting-code sets the priority to a higher value and resets the ttl
> to a certain value (no idea which one, but the default is 10 minutes and
> the maximum a day). The srv-record-compare-function however checks also
> using priority and weight and returns a negative response if they are
> different. I would think that fs maybe then readds the original srv-records
> (with priority 0) when it requeries the dns. Those entries will also
> increase in priority and ttl when they are added, causing the cache to keep
> growing ...
> Nscd is also being used for dns-caching, which doesn't help, but I'm not
> sure if that is the problem as sofia_dig seems to return valid values
> (except maybe ttl).
>
>
>  I would think that ttl is never touched and that the cached is cleared
> when the ttl expires, but I have no idea when the dns-cache is cleared in
> FS...
>
> I know this is maybe a lot of text, but any info on this topic (sofia dns
> cache) is welcome.
>
> Thanks,
>
> Michel
>
>
>
>
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-- 

*Brian West*
brian at freeswitch.org


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