Need advice on "Hex signed 2's complement" alrgorithm

[fantuz]

this post to track the progress of "Hex signed 2's complement" rework.

TTL value is generated from headers, but not reflected correctly in UDP packet due to wrong conversion HEX to HEX 2's.

Tracking to find help and close soon, is trivial to fix.

[fantuz]

TTL is not perfectly extracted out of HTTP headers.

Rewriting of TTL into DNS wire packet works like a charm, when needed to override the original packet's TTL.
Normally is up to the DoH provider to write the same (good) value on HTTP/DNS wire packet as into HTTP headers, contained in ache-control/max-age.

Hence, the whole problem is solved.
Algorithm is OK, technique is validated by compliance to RFC standard