e6acf0bab7
## Problem A `BrowseServices` subscription with `"ifindex":0` (browse all interfaces) receives a continuous flap of `added`/`removed` events for a service that is still present — within a second, and with no goodbye packet involved. ## Root cause For `ifindex==0`, `mdns_browser_revisit_cache()` looked up each mDNS scope's cache separately and called `mdns_manage_services_answer()` **once per scope**. That function derives `removed` events by diffing the browser's *global* discovered-service list (all interfaces, filtered only by owner family) against the single answer it's handed. So with ≥2 mDNS-relevant interfaces of the same family, a service present on interface A isn't in interface B's answer and is spuriously removed while B is reconciled, then re-added on the next revisit tick. ## Fix Accumulate the pruned cache answers from every matching mDNS scope into one combined `DnsAnswer` and reconcile **once**, so removals diff the global list against the union across interfaces. Items are merged with `dns_answer_add_full()` (not `dns_answer_extend()`, which defaults each item's `until` to `USEC_INFINITY` and would skew the RFC 6762 §5.2 TTL-maintenance schedule). The single-interface (`ifindex>0`) path is unchanged. ## Test `TEST-89-RESOLVED-MDNS.sh` gains `testcase_browse_ifindex_zero_no_flap`: it adds a service-less dummy mDNS link to guarantee ≥2 same-family scopes (the flap precondition), browses `ifindex=0`, waits for discovery, then asserts **zero** `removed` events while every publisher stays up. The subscription uses `varlinkctl --timeout=infinity`, since it sits idle after discovery and the default 45s idle timeout would sever it (and the assertion) mid-observation. ## Testing status Builds clean; `shellcheck -x` clean. First CI round: `TEST-89` (including this testcase) passed on all mkosi platforms; the failing jobs all traced to unrelated flakes/infra.
System and Service Manager
Details
Most documentation is available on systemd's web site.
Assorted, older, general information about systemd can be found in the systemd Wiki.
Information about build requirements is provided in the README file.
Consult our NEWS file for information about what's new in the most recent systemd versions.
Please see the Code Map for information about this repository's layout and content.
Please see the Hacking guide for information on how to hack on systemd and test your modifications.
Please see our Contribution Guidelines for more information about filing GitHub Issues and posting GitHub Pull Requests.
When preparing patches for systemd, please follow our Coding Style Guidelines.
If you are looking for support, please contact our mailing list, join our IRC channel #systemd on libera.chat or Matrix channel
Stable branches with backported patches are available in the stable repo.
We have a security bug bounty program sponsored by the Sovereign Tech Fund hosted on YesWeHack
Repositories with distribution packages built from git main are available on OBS, and also repositories with packages built from the latest stable release