python unbound client bug?

Unbound
1

See:

$ dig _aiven-challenge.nohats.ca txt +short
"token=someveryrandomstring,expiry=never"

doing the same with unbound python:

import os
from unbound import ub_ctx,ub_strerror,RR_TYPE_TXT,RR_TYPE_A,RR_CLASS_IN

ctx = ub_ctx()
ctx.resolvconf("/etc/resolv.conf")
if os.path.isfile("/etc/unbound/dnssec-root.key"):
     ctx.add_ta_file("/etc/unbound/dnssec-root.key") #read public keys for DNSSEC verification
status, result = ctx.resolve(f"_aiven-challenge.nohats.ca.", RR_TYPE_TXT, RR_CLASS_IN)

if status == 0 and result.havedata:
     print(result.data.data)

$ python test.py [b"'token=someveryrandomstring,expiry=never"]

Note there is a single quote at the beginning of the string (and not at the end)

This is with python3-unbound-1.17.1-1.fc37.x86_64

Paul

2

Hi Paul,

The single/double quotes mixup seems like a funny coincidence.
result.data.data includes the rdata which in this case (TXT) is the character string(s). So also the length of the character string at the start which in this case happens to be presented as '.
For this specific example (single character string) you can skip the first byte but I believe the correct approach is to provide something like 'as_txt_list()' method similar to the other methods to cleanly handle the possible multiple length occurrences there.

For now something like the following would help you with parsing TXT rdata (more or less similar to what is there now for domain names):