reSIProcate

Mailing Lists

Source Code

Google Search:



< Previous by Date Date Index Next by Date >
< Previous in Thread Thread Index  

Re: [reSIProcate] DNS not returning entries after 408?

This case has been handled, by deferred destruction of the DnsResult. TransactionState never calls delete explicitly on its DnsResult, instead it calls DnsResult::destroy(). (when DnsResult::destroy() is called, the DnsResult checks if it has outstanding queries, and if so it will wait for these to come in before deleting itself.)

Best regards,
Byron Campen
 
What if the Transaction State Obj expired (deleted about 32 seconds) before DNS look up returns?
 
This may cause core dump since the DNS Result used by DNS lookup is deleted when Transaction State Obj is deleted.
 

Regards,

Frank Yuan
 

From: resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Byron Campen
Sent: Thursday, December 07, 2006 1:32 PM
To: Scott Godin
Cc: resiprocate-devel@xxxxxxxxxxxxxxxxxxxx
Subject: Re: [reSIProcate] DNS not returning entries after 408?

We can't unblacklist stuff that was blacklisted because of a 503. If all of the available servers are keeling over from overload, and sending 503s, we are supposed to just shut up and wait for the blacklists to expire. However, it is reasonable to say that this behavior is not warranted in cases where we have blacklisted due to a timeout. If we wish to treat these two scenarios differently, maybe a greylisting concept is what we should use.

Best regards,
Byron Campen

Before the recent changes, that way I understood it the blacklisting was supposed to work as follows:

1.        Only blacklist an entry if there other DNS entries to try.

2.       If we have ended up blacklisting all entries from a particular lookup, then un-blacklist them all and let the next request start the cycle again.

Scott

From: resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Byron Campen
Sent: Thursday, December 07, 2006 2:01 PM
To: Jeremy Geras
Cc: resiprocate-devel@xxxxxxxxxxxxxxxxxxxx
Subject: Re: [reSIProcate] DNS not returning entries after 408?

          This is happening because the stack is blacklisting the tuple that your server was running on, because it didn't respond. This blacklist (currently) lasts 32s. I was thinking about making this duration configurable. Does anyone want to have a discussion about whether blacklisting on a UDP timeout is something we want to be doing? It seems to me that we might need to have a concept of "greylisting", where greylisted tuples will only be used if they are all that remains to be tried. (This is opposed to a blacklisted tuple, which we should never try, since chances are we have been explicitly told, with a 503, to leave the tuple alone for a while.) Any thoughts? (anyone?)

Best regards,

Byron Campen

Hi,

I’m using the latest code from SVN (updated today), and I’ve encountered an issue with DNS in the following case:

Client                                          Registrar

      REGISTER (due to user login)------------->

      <---------------------------------- 200 OK

(at this point the Registrar becomes unavailable – its IP is still reachable, but nothing is listening on UDP port 5060)

      re-REGISTER (due to Expires timer)------->

(~ 30 seconds go by and then I get a 408 from DUM)

(client sits idle for ~ 30 seconds more)

      REGISTER -------------------------------->

(Get a 503 Service Unavailable immediately from DUM)

(sit idle for any amount of time)

      REGISTER -------------------------------->

      <---------------------------------- 200 OK

My client is set up to use only UDP as a transport.  I’m using DUM.  I’ve looked at the logs, and it seems the reason I’m getting the 503 is that there aren’t any DNS entries for my registrar: “Ran out of dns entries for 192.168.1.172. Send 503”.  But this doesn’t make sense, as there definitely should be entries (and since I can register if I try once again after I get the 503).

If I go back to an older revision (6609 which is from back in September), I don’t have this issue – i.e. I don’t get the 503, my last REGISTER actually goes out on the wire and I get my expected 200 OK.

Any thoughts?

Thanks,

 - Jeremy -

_______________________________________________

resiprocate-devel mailing list

_______________________________________________
resiprocate-devel mailing list