Fix Filter AAAA: preserve AuthoritativeAnswer on synthesized NODATA response - #2140
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Fix Filter AAAA: preserve AuthoritativeAnswer on synthesized NODATA response#2140IReclaimer wants to merge 1 commit into
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…esponse The synthesized NODATA response always hardcoded authoritativeAnswer to false, even when the original response was authoritative. This is correct when filtering a recursively-resolved/forwarded answer (AA=0 is right there anyway), but wrong when the server is authoritative for the zone being filtered. The confirmed negative answer gets downgraded to non-authoritative for no reason. This matters beyond protocol correctness: a resolver forwarding to this server (e.g. Unbound with a forward-zone) treats a non-authoritative NODATA as inconclusive and falls back to real recursive resolution instead of trusting it, silently defeating the filter for anyone running this behind a forwarding resolver for their own authoritative zones. RecursionDesired/RecursionAvailable a few arguments later were already being carried over correctly from the original response; this just extends the same treatment to AuthoritativeAnswer.
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Fixes #2139
The synthesized NODATA response always hardcoded authoritativeAnswer to false, even when the original response was authoritative. This is correct when filtering a recursively-resolved/forwarded answer (AA=0 is right there anyway), but wrong when the server is authoritative for the zone being filtered. The confirmed negative answer gets downgraded to non-authoritative for no reason.
This matters beyond protocol correctness: a resolver forwarding to this server (e.g. Unbound with a forward-zone) treats a non-authoritative NODATA as inconclusive and falls back to real recursive resolution instead of trusting it, silently defeating the filter for anyone running this behind a forwarding resolver for their own authoritative zones.
RecursionDesired/RecursionAvailable a few arguments later were already being carried over correctly from the original response; this just extends the same treatment to AuthoritativeAnswer. See #2139 for full reproduction steps.