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Re: Retry mechanism w/ DNS Format Error?


On Wed, 5 Jan 2005, Ulrich Drepper wrote:
Pekka Savola wrote:
Now, apparently the RHL9 resolver code cannot cope with FormErr code quickly, but has to resort to timeouts. (I've been unable to verify this on a newer glibc because it no longer creates the bitstring queries,

Sure they do, if use tell it. Set the ip6-bytestring option in resolv.conf.

OK, good to know; I didn't realize this support was still there as optional :)


Anyway, I tried to reproduce it, but your server is not accessible to me. I took only a brief look at the code. In the one place where FORMERR is handled, it marks the error as not recoverable. I'm not sure whether this is the right place or whether unrecoverable errors are handled appropriately.

As long as I cannot reproduce it I cannot do much unless you provide detailed information about the code flow for these responses.

And please file any such reply in bugzilla, else it might get lost.

The server is stock BIND 9.3.0, where they removed the support for bytestring queries. I think there are lots of servers out there (and more on the way), but if you want to test with one, you can use "gap.netcore.fi". It doesn't do much of anything, but should send FormErr messages for bitstring queries..


Unfortunately I don't have a newer glibc system handy just yet to do any testing myself, maybe next week unless you or someone else has reproduced this by then.

--
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings


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