dig/nslookup in new DNS module

[krejkrejkrej]

I'm developing a new DNS API module for acme.sh. My working version works fine, but relies on the dig command to do DNS lookups on a specific server. I now found out that dig is not available in the test suite (please add that restriction to the code-of-conduct page!) and it fails.

The provider I work with does not have an API call to fetch data directly from their servers, but instructs me to use DNS lookup going directly to one of the NS servers for the relevant zone, like dig @"${NS}" +short TXT "$acme_hostname" to retrieve the authoritative list of TXT records. I am aware of _ns_lookup function, but that will probably not provide a reliable way to look up records in my providers DNS service, and I want to stick to the given instructions.

How can I perform plain old udp based lookups in acme.sh?