[nsd-users] Prevent name compression on some RR types?

Matthijs Mekking matthijs at nlnetlabs.nl
Mon Nov 19 09:34:02 UTC 2012


On 11/17/2012 11:05 AM, Stephane Bortzmeyer wrote:
> RFC 6742, section 2.4.1.2, says:
> 
>> A sender MUST NOT use DNS name compression on the FQDN field when
>> transmitting an LP RR.
> 
> I do not see how to implement this with NSD 3. When I call
> zadd_rdata_domain() in zparser.y, there is apparently no option to
> register in the compiled zone database the fact that this must not be
> compressed. As a result, the name is compressed, violating the RFC.

There is: RDATA formats in NSD are registered in dns.c. There is a table
of RRs, describing each RDATA formats. For LP, this would be:

{ RDATA_WF_SHORT, RDATA_WF_UNCOMPRESSED_DNAME }
{ RDATA_ZF_SHORT, RDATA_ZF_DNAME }

> Such a rule seems to have been present only for DNSSEC-related RR
> types until now. These DNSSEC RR types have a special handling in the
> name server but I find nothing for other types.

This new RR type is perfectly following RFC 3597, Handling of Unknown
DNS RR Types:

   Future specifications for new RR types that contain domain names
   within their RDATA MUST NOT allow the use of name compression for
   those names, and SHOULD explicitly state that the embedded domain
   names MUST NOT be compressed.

Best regards,
  Matthijs

> 
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