fix: send goodbye packets under conflict-resolved names - #495
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Thank you for the fix! LGTM, with a minor comment inline.
When probing renames a record due to a name conflict (RFC 6762 section 9), announcements and query responses use the new name via DnsRegistry::name_changes, but unregister_service still built the TTL=0 goodbye records from the original ServiceInfo names. Peers that cached the renamed records never saw a matching goodbye, so an auto-renamed instance lingered in browsers until its record TTLs expired after unregister or shutdown. Resolve the service fullname and hostname through the interface's DnsRegistry when building the goodbye packet, so the goodbye carries the names peers actually cached. Add a regression test that forces a conflict rename and verifies a browser sees ServiceRemoved for the renamed instance promptly after unregister.
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Problem
When probing renames a record after a name conflict (RFC 6762 section 9), announcements and query responses correctly use the new name via
DnsRegistry::name_changes/resolve_name. Butunregister_servicestill builds the TTL=0 goodbye records from the originalServiceInfonames.Peers on the link only ever cached the renamed records, so the goodbye never matches anything in their caches. An auto-renamed instance therefore lingers in browse lists until its record TTLs expire after
unregister()orshutdown(), instead of disappearing within seconds.Fix
Resolve the service fullname and hostname through the interface's
DnsRegistry(the sameresolve_nameused byprepare_announce) when building the goodbye packet inunregister_service, so the goodbye carries the names peers actually cached. Interfaces without a registry entry keep the original names, as before.Test
Added
test_goodbye_uses_conflict_resolved_name: it forces a conflict rename between two daemons, resolves the renamed instance from a third (browser) daemon, unregisters the renamed service, and asserts the browser receivesServiceRemovedfor the renamed fullname well before any TTL could expire.The test fails on current
main(no goodbye ever observed for the renamed instance) and passes with this change. Fullcargo testpasses.