fix: override iTip Broker to fix several issues

apps/dav/composer/composer/autoload_classmap.php

@@ -111,6 +111,7 @@
     'OCA\\DAV\\CalDAV\\Sharing\\Service' => $baseDir . '/../lib/CalDAV/Sharing/Service.php',
     'OCA\\DAV\\CalDAV\\Status\\StatusService' => $baseDir . '/../lib/CalDAV/Status/StatusService.php',
     'OCA\\DAV\\CalDAV\\TimezoneService' => $baseDir . '/../lib/CalDAV/TimezoneService.php',
+    'OCA\\DAV\\CalDAV\\TipBroker' => $baseDir . '/../lib/CalDAV/TipBroker.php',
     'OCA\\DAV\\CalDAV\\Trashbin\\DeletedCalendarObject' => $baseDir . '/../lib/CalDAV/Trashbin/DeletedCalendarObject.php',
     'OCA\\DAV\\CalDAV\\Trashbin\\DeletedCalendarObjectsCollection' => $baseDir . '/../lib/CalDAV/Trashbin/DeletedCalendarObjectsCollection.php',
     'OCA\\DAV\\CalDAV\\Trashbin\\Plugin' => $baseDir . '/../lib/CalDAV/Trashbin/Plugin.php',

apps/dav/composer/composer/autoload_static.php

@@ -126,6 +126,7 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\CalDAV\\Sharing\\Service' => __DIR__ . '/..' . '/../lib/CalDAV/Sharing/Service.php',
         'OCA\\DAV\\CalDAV\\Status\\StatusService' => __DIR__ . '/..' . '/../lib/CalDAV/Status/StatusService.php',
         'OCA\\DAV\\CalDAV\\TimezoneService' => __DIR__ . '/..' . '/../lib/CalDAV/TimezoneService.php',
+        'OCA\\DAV\\CalDAV\\TipBroker' => __DIR__ . '/..' . '/../lib/CalDAV/TipBroker.php',
         'OCA\\DAV\\CalDAV\\Trashbin\\DeletedCalendarObject' => __DIR__ . '/..' . '/../lib/CalDAV/Trashbin/DeletedCalendarObject.php',
         'OCA\\DAV\\CalDAV\\Trashbin\\DeletedCalendarObjectsCollection' => __DIR__ . '/..' . '/../lib/CalDAV/Trashbin/DeletedCalendarObjectsCollection.php',
         'OCA\\DAV\\CalDAV\\Trashbin\\Plugin' => __DIR__ . '/..' . '/../lib/CalDAV/Trashbin/Plugin.php',

apps/dav/lib/CalDAV/Schedule/Plugin.php

@@ -11,6 +11,7 @@
 use OCA\DAV\CalDAV\CalendarHome;
 use OCA\DAV\CalDAV\CalendarObject;
 use OCA\DAV\CalDAV\DefaultCalendarValidator;
+use OCA\DAV\CalDAV\TipBroker;
 use OCP\IConfig;
 use Psr\Log\LoggerInterface;
 use Sabre\CalDAV\ICalendar;
@@ -85,6 +86,13 @@ public function initialize(Server $server) {
 		);
 	}
 
+	/**
+	 * Returns an instance of the iTip\Broker.
+	 */
+	protected function createITipBroker(): TipBroker {
+		return new TipBroker();
+	}
+
 	/**
 	 * Allow manual setting of the object change URL
 	 * to support public write
@@ -168,7 +176,7 @@ public function calendarObjectChange(RequestInterface $request, ResponseInterfac
 			$calendarNode = $this->server->tree->getNodeForPath($calendarPath);
 			// extract addresses for owner
 			$addresses = $this->getAddressesForPrincipal($calendarNode->getOwner());
-			// determain if request is from a sharee
+			// determine if request is from a sharee
 			if ($calendarNode->isShared()) {
 				// extract addresses for sharee and add to address collection
 				$addresses = array_merge(

apps/dav/lib/CalDAV/TipBroker.php

@@ -0,0 +1,187 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\DAV\CalDAV;
+
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\ITip\Broker;
+use Sabre\VObject\ITip\Message;
+
+class TipBroker extends Broker {
+
+	public $significantChangeProperties = [
+		'DTSTART',
+		'DTEND',
+		'DURATION',
+		'DUE',
+		'RRULE',
+		'RDATE',
+		'EXDATE',
+		'STATUS',
+		'SUMMARY',
+		'DESCRIPTION',
+		'LOCATION',
+
+	];
+
+	/**
+	 * This method is used in cases where an event got updated, and we
+	 * potentially need to send emails to attendees to let them know of updates
+	 * in the events.
+	 *
+	 * We will detect which attendees got added, which got removed and create
+	 * specific messages for these situations.
+	 *
+	 * @return array
+	 */
+	protected function parseEventForOrganizer(VCalendar $calendar, array $eventInfo, array $oldEventInfo) {
+		// Merging attendee lists.
+		$attendees = [];
+		foreach ($oldEventInfo['attendees'] as $attendee) {
+			$attendees[$attendee['href']] = [
+				'href' => $attendee['href'],
+				'oldInstances' => $attendee['instances'],
+				'newInstances' => [],
+				'name' => $attendee['name'],
+				'forceSend' => null,
+			];
+		}
+		foreach ($eventInfo['attendees'] as $attendee) {
+			if (isset($attendees[$attendee['href']])) {
+				$attendees[$attendee['href']]['name'] = $attendee['name'];
+				$attendees[$attendee['href']]['newInstances'] = $attendee['instances'];
+				$attendees[$attendee['href']]['forceSend'] = $attendee['forceSend'];
+			} else {
+				$attendees[$attendee['href']] = [
+					'href' => $attendee['href'],
+					'oldInstances' => [],
+					'newInstances' => $attendee['instances'],
+					'name' => $attendee['name'],
+					'forceSend' => $attendee['forceSend'],
+				];
+			}
+		}
+
+		$messages = [];
+
+		foreach ($attendees as $attendee) {
+			// An organizer can also be an attendee. We should not generate any
+			// messages for those.
+			if ($attendee['href'] === $eventInfo['organizer']) {
+				continue;
+			}
+
+			$message = new Message();
+			$message->uid = $eventInfo['uid'];
+			$message->component = 'VEVENT';
+			$message->sequence = $eventInfo['sequence'];
+			$message->sender = $eventInfo['organizer'];
+			$message->senderName = $eventInfo['organizerName'];
+			$message->recipient = $attendee['href'];
+			$message->recipientName = $attendee['name'];
+
+			// Creating the new iCalendar body.
+			$icalMsg = new VCalendar();
+
+			foreach ($calendar->select('VTIMEZONE') as $timezone) {
+				$icalMsg->add(clone $timezone);
+			}
+			// If there are no instances the attendee is a part of, it means
+			// the attendee was removed and we need to send them a CANCEL message.
+			// Also If the meeting STATUS property was changed to CANCELLED
+			// we need to send the attendee a CANCEL message.
+			if (!$attendee['newInstances'] || $eventInfo['status'] === 'CANCELLED') {
+
+				$message->method = $icalMsg->METHOD = 'CANCEL';
+				$message->significantChange = true;
+				// clone base event
+				$event = clone $eventInfo['instances']['master'];
+				// alter some properties
+				unset($event->ATTENDEE);
+				$event->add('ATTENDEE', $attendee['href'], ['CN' => $attendee['name'],]);
+				$event->DTSTAMP = gmdate('Ymd\\THis\\Z');
+				$event->SEQUENCE = $message->sequence;
+				$icalMsg->add($event);
+
+			} else {
+				// The attendee gets the updated event body
+				$message->method = $icalMsg->METHOD = 'REQUEST';
+
+				// We need to find out that this change is significant. If it's
+				// not, systems may opt to not send messages.
+				//
+				// We do this based on the 'significantChangeHash' which is
+				// some value that changes if there's a certain set of
+				// properties changed in the event, or simply if there's a
+				// difference in instances that the attendee is invited to.
+
+				$oldAttendeeInstances = array_keys($attendee['oldInstances']);
+				$newAttendeeInstances = array_keys($attendee['newInstances']);
+
+				$message->significantChange =
+					$attendee['forceSend'] === 'REQUEST' ||
+					count($oldAttendeeInstances) !== count($newAttendeeInstances) ||
+					count(array_diff($oldAttendeeInstances, $newAttendeeInstances)) > 0 ||
+					$oldEventInfo['significantChangeHash'] !== $eventInfo['significantChangeHash'];
+
+				foreach ($attendee['newInstances'] as $instanceId => $instanceInfo) {
+					$currentEvent = clone $eventInfo['instances'][$instanceId];
+					if ($instanceId === 'master') {
+						// We need to find a list of events that the attendee
+						// is not a part of to add to the list of exceptions.
+						$exceptions = [];
+						foreach ($eventInfo['instances'] as $instanceId => $vevent) {
+							if (!isset($attendee['newInstances'][$instanceId])) {
+								$exceptions[] = $instanceId;
+							}
+						}
+
+						// If there were exceptions, we need to add it to an
+						// existing EXDATE property, if it exists.
+						if ($exceptions) {
+							if (isset($currentEvent->EXDATE)) {
+								$currentEvent->EXDATE->setParts(array_merge(
+									$currentEvent->EXDATE->getParts(),
+									$exceptions
+								));
+							} else {
+								$currentEvent->EXDATE = $exceptions;
+							}
+						}
+
+						// Cleaning up any scheduling information that
+						// shouldn't be sent along.
+						unset($currentEvent->ORGANIZER['SCHEDULE-FORCE-SEND']);
+						unset($currentEvent->ORGANIZER['SCHEDULE-STATUS']);
+
+						foreach ($currentEvent->ATTENDEE as $attendee) {
+							unset($attendee['SCHEDULE-FORCE-SEND']);
+							unset($attendee['SCHEDULE-STATUS']);
+
+							// We're adding PARTSTAT=NEEDS-ACTION to ensure that
+							// iOS shows an "Inbox Item"
+							if (!isset($attendee['PARTSTAT'])) {
+								$attendee['PARTSTAT'] = 'NEEDS-ACTION';
+							}
+						}
+					}
+
+					$currentEvent->DTSTAMP = gmdate('Ymd\\THis\\Z');
+					$icalMsg->add($currentEvent);
+				}
+			}
+
+			$message->message = $icalMsg;
+			$messages[] = $message;
+		}
+
+		return $messages;
+	}
+
+}