RFC 2136: Dynamic updates

[miekg]

https://datatracker.ietf.org/doc/html/rfc2136

2.4.3 - RRset Does Not Exist

....

For this prerequisite, a requestor adds to the section a single RR whose NAME and TYPE are equal to that of the RRset whose nonexistence is required. The RDLENGTH of this record is zero (0), and RDATA field is therefore empty. CLASS must be specified as NONE in order to distinguish this condition from a valid RR whose RDLENGTH is naturally zero (0) (for example, the NULL RR). TTL must be specified as zero (0).

These are normal RRs where the RDATA is cut off, CLASS is not important here.

This issue will detail how to make those and where this lib currently fails to do so (or for which RR types)

• [x] Parsing with NewRR into RR with rdlenght=0
• [x] Packing msg with rdlength=0 RR
• [ ] Unpacking TestNoRdataUnpack - off-by-one error in unpack/pack somewhere
• [ ] Making directly from struct - guessing this works
• [ ] Setting Rdlength to zero yourself - guessing this works