[SelfRef]

Summary

A sync-collection REPORT on a cached webcal subscription (X-NC-CalDAV-Webcal-Caching: On) answers with another calendar's changes. CachedSubscription::getChanges() passes the call on to Sabre\CalDAV\Calendar::getChanges(), which calls getChangesForCalendar() without a calendar type. The backend then uses the default CALENDAR_TYPE_CALENDAR, so it reads oc_calendars and oc_calendarchanges for the regular calendar whose id matches the subscription's id.

What clients see:

• An initial sync lists none of the subscription's events. The other calendar's object URIs are not children of the subscription, so Sabre drops them.
• The sync token belongs to that other calendar, so later syncs follow its changes, not the subscription's.
• With no regular calendar of that id, the backend returns null.

The other methods of CachedSubscription (getChild, getChildren, getMultipleChildren, childExists, calendarQuery) already pass CALENDAR_TYPE_SUBSCRIPTION. getChanges() now does too. The refresh job already records the subscription's changes under that type (addChanges(…, CALENDAR_TYPE_SUBSCRIPTION)), so incremental sync works as it does for regular calendars.

Reproduce

On a fresh instance (allow_local_remote_servers on, so the feed can be served locally):

1. Create a calendar and add an event to personal (calendar id 1).
2. Subscribe to an ICS feed with one event (subscription id 1) and run its RefreshWebcalJob.
3. Send sync-collection with an empty token to the subscription, with X-NC-CalDAV-Webcal-Caching: On.

Before (oc_calendars: personal synctoken 3; oc_calendarsubscriptions: feed synctoken 2):

<d:sync-token>http://sabre.io/ns/sync/3</d:sync-token>

No events, and personal's token.

After:

<d:href>/remote.php/dav/calendars/admin/feed/35674c97-3d50-4ced-abeb-416a09bba6ca.ics</d:href>
<d:status>HTTP/1.1 200 OK</d:status>
<d:sync-token>http://sabre.io/ns/sync/2</d:sync-token>

The feed's event, and the subscription's own token.

Found while adding support for subscriptions to a CalDAV client, which uses sync-collection for every calendar.

TODO

• Fix
• Unit test (CachedSubscriptionTest::testGetChanges; it fails without the fix)

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[kesselb]

/backport to stable35

[kesselb]

/backport to stable34

[kesselb]

/backport to stable33

[kesselb]

/backport to stable32