auth: can't provision arbitrary octets in PTR rdata via REST API

[peterthomassen]

• This is not a support question, I have read about opensource and will send support questions to the IRC channel, GitHub Discussions or the mailing list.

• I have read and understood the 'out in the open' support policy

• Program: Authoritative

• Issue type: Bug report

Short description

RFC 6763 Section 4.1.1 says that "arbitrary Net-Unicode text" can be used in PTR rdata for the purposes of naming instances in the context of this RFC. However, auth's REST API does not accept all octets (e.g., \040, \041).

Environment

• Operating system: Linux
• Software version: 4.9
• Software source: PowerDNS repository

Steps to reproduce

1. Add a PTR record via the REST API that contains \040

Expected behaviour

Should work

Actual behaviour

Auth says the record is not in expected format

Other information

@Habbie told me that perhaps there might be a flag for this in the future.

[peterthomassen]

Additional info: It's possible to provision \000, for example PTR foo\000bar.INTERNAL., via the REST API. Result:

$ docker compose exec nslord pdnsutil list-zone foo.com | grep PTR
foo.com	3600	IN	PTR	foo\000bar.INTERNAL

When trying PTR foo\040bar.INTERNAL., the response is 422 with the following content:

{"error": "Record foo.com./PTR 'foo\\(bar.INTERNAL.': Not in expected format (parsed as 'foo(bar.INTERNAL.')"}

Other values between \000 and \063 which I've tried and that don't work: \034, \036, \040, \041, \059
I believe all others in this ranged have worked.

Update: The REST API input is canonicalized via dnspython (.to_wire() and back .to_text(), so we can identify duplicate records easily). I'm not sure whether the above is caused by sending \040 to the pdns API or whether really ( is sent. -- Either way, our use case is that any valid input should work, so things don't depend on which presentation format is accidentally preferred.

(Note that this is log output via Python, and I cannot tell immediately whether pdns really returns \\( in the first part of the response body, or whether it is \( and the second \ is added by Python. Let me know if you need this in more detail.)