[Pdns-users] Exception: unknown escape sequence on NAPTR regex

Peter Fern pdns at obfusc8.org
Tue Aug 5 03:06:58 UTC 2008

Duane wrote:
> Peter Fern wrote:
>> Duane wrote:
>>> It's pointless trying to expand regular expressions from within the DNS
>>> server, either it will increase load unnecessarily or the regular
>>> expressions were designed to be expanded by a client requesting the
>>> information.
>> I'm aware that parsing of the regex is meant to be done client-side, all
>> I'm trying to do is get PowerDNS to actually serve them as they are in
>> the backend.  If you look at the original post
>> (48855B45.6020604 at obfusc8.org) and 48916317.3040704 at obfusc8.org it
>> should be clear what the problem is, and that it's because pdns *is*
>> trying to parse escape sequences that there's a problem.
> and I'm telling you that it's pointless trying to get PDNS to do that
> because the load will be substantially increased, you are MUCH better
> off expanding the regex before you hand it off to PDNS.

All I'm trying to do is get PDNS to return a record verbatim from the 
backend (actually, I've just reviewed the RFC, which says a 
double-backslash in the zone must return a single in the response).  
Simply matching '\\' and returning '\' is a low-cost operation, and 
required for RFC compliance - I can't believe that this will result in a 
significant load increase.  In any case, load is not an issue for our 
application - we can through more hardware at it.  And expanding the 
regex before adding to the backend is entirely impractical since we'd 
potentially have to insert hundreds of thousands of records to match a 
single pattern with a backref, depending on the numbering scheme.

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