Address review findings on PR #25:
- Refactor resolve_query to take a pre-parsed DnsPacket. Parse-error
handling moves to the UDP caller, eliminating the double warn! line
on malformed UDP queries.
- Enforce MIN_MSG_LEN=12 (DNS header) in handle_dot_connection so
query_id extraction is always reading client-sent bytes, not the
zeroed buffer tail.
- Parse the DoT query before calling resolve_query and retain it, so
SERVFAIL responses can echo the original question section via
response_from(). Parse failures send FORMERR with the client id.
- Extract write_framed() helper for length-prefix + flush, reused by
success, SERVFAIL, and FORMERR paths.
- Back off 100ms on listener.accept() errors to avoid tight-looping
on fd exhaustion.
- Replace the hardcoded 127.0.0.1:53 upstream in dot_nxdomain_for_unknown
with a bound-but-unresponsive UDP socket owned by the test, making it
independent of the host's local resolver. Test now runs in ~220ms
(timeout lowered to 200ms) instead of 3s and asserts the question is
echoed in the SERVFAIL response.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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