[Pdns-dev] PowerDNS Recursor 3.1.2 released!

Darren Gamble darren.gamble at sjrb.ca
Wed Jun 28 14:26:38 CEST 2006

Good day,

We applied this patch and built new packages.

The patch unfortunately seems to have no effect on the issue. The good
news, at least, is that we can now easily reproduce the issue.

The issue does indeed happen in the way that we described below.  We
reproduced it as follows:

- Start pdns.
- Query an A record in the "problem" domain.
- Jump the system clock on the machine ahead to "expire" the entry
(rather than wait around)
- Query the same A record.
- Query the NS records for the domain to confirm the problem.

This seems to be 100% reproducible.  But, it doesn't happen the first
time we query for the name (which happened pre 3.1.2).  And, it doesn't
happen if we use wipe-cache to expire the domain.  Perhaps some code
behaves differently if there is information in the cache which is
expired, as opposed to no information at all?

At the time of this message, "monster.ca" has this problem, if one needs
an example.


Darren Gamble
Planner, Regional Services
Shaw Cablesystems GP
630 - 3rd Avenue SW
Calgary, Alberta, Canada
T2P 4L4
(403) 781-4948

> -----Original Message-----
> From: bert hubert [mailto:bert.hubert at netherlabs.nl]
> Sent: Tuesday, June 27, 2006 2:14 PM
> To: Darren Gamble
> Cc: pdns-dev at mailman.powerdns.com
> Subject: Re: [Pdns-dev] PowerDNS Recursor 3.1.2 released!
> On Tue, Jun 27, 2006 at 02:08:46PM -0600, Darren Gamble wrote:
> > 1) Cache gets the parent's NS records.
> > 2) Cache gets the server's NS records, replacing the parent's
> > (typically in the same query)
> Indeed.
> > 3) Cache somehow gets both sets of servers added at the same time
> > the parent's NS records expire.
> This is the part I can't figure out. I've tried a lot of things to
> this before, like wiping data using rec_control etc.
> > We can test the patch.  We can also try the patch on our production
> > servers, if you could point us in the direction of the SRPM you use
> > make your packages on your download page.
> Kees Monshouwer has an SRPM here which you might be able to patch:
> ftp://ftp.monshouwer.com/pub/linux/pdns-recursor/SRPMS
> Alternatively, I myself build by taking the pdns-recursor sources, and
> running:
> rpmbuild -bb pdns-recursor.spec
> Where pdns-recursor.spec can be found here:
> http://wiki.powerdns.com/projects/trac/browser/trunk/pdns/pdns/pdns-
> recursor.spec
> It includes some paths that refer to my specific versions of gcc and
> boost,
> but that is harmless on systems without a /home/ahu or
> I never got the hang of making SRPMs myself hehe.
> Good luck and thanks for testing.
> --
> http://www.PowerDNS.com      Open source, database driven DNS Software
> http://netherlabs.nl              Open and Closed source services

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