Support iMIP invitations from Mail

Signed-off-by: Anna Larch <anna@nextcloud.com>

9 files changed, 698 insertions, 11 deletions

diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index 2bbdc51f42e..42df838523d 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -1864,6 +1864,10 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 			}
 		}
 
+		if(isset($options['uid'])) {
+			$outerQuery->andWhere($outerQuery->expr()->eq('uid', $outerQuery->createNamedParameter($options['uid'])));
+		}
+
 		if (!empty($options['types'])) {
 			$or = $outerQuery->expr()->orX();
 			foreach ($options['types'] as $type) {
diff --git a/apps/dav/lib/CalDAV/CalendarHome.php b/apps/dav/lib/CalDAV/CalendarHome.php
index ceeba31800e..cd6ae1c2f7f 100644
--- a/apps/dav/lib/CalDAV/CalendarHome.php
+++ b/apps/dav/lib/CalDAV/CalendarHome.php
@@ -206,7 +206,6 @@ class CalendarHome extends \Sabre\CalDAV\CalendarHome {
 		return $this->caldavBackend->calendarSearch($principalUri, $filters, $limit, $offset);
 	}
 
-
 	public function enableCachedSubscriptionsForThisRequest() {
 		$this->returnCachedSubscriptions = true;
 	}
diff --git a/apps/dav/lib/CalDAV/CalendarImpl.php b/apps/dav/lib/CalDAV/CalendarImpl.php
index 27a428a4075..a04e520c6bc 100644
--- a/apps/dav/lib/CalDAV/CalendarImpl.php
+++ b/apps/dav/lib/CalDAV/CalendarImpl.php
@@ -29,10 +29,19 @@ namespace OCA\DAV\CalDAV;
 
 use OCA\DAV\CalDAV\Auth\CustomPrincipalPlugin;
 use OCA\DAV\CalDAV\InvitationResponse\InvitationResponseServer;
+use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Calendar\Exceptions\CalendarException;
 use OCP\Calendar\ICreateFromString;
 use OCP\Constants;
+use OCP\Security\ISecureRandom;
+use Psr\Log\LoggerInterface;
 use Sabre\DAV\Exception\Conflict;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VEvent;
+use Sabre\VObject\Document;
+use Sabre\VObject\ITip\Message;
+use Sabre\VObject\Property\VCard\DateTime;
+use Sabre\VObject\Reader;
 use function Sabre\Uri\split as uriSplit;
 
 class CalendarImpl implements ICreateFromString {
@@ -46,13 +55,6 @@ class CalendarImpl implements ICreateFromString {
 	/** @var array */
 	private $calendarInfo;
 
-	/**
-	 * CalendarImpl constructor.
-	 *
-	 * @param Calendar $calendar
-	 * @param array $calendarInfo
-	 * @param CalDavBackend $backend
-	 */
 	public function __construct(Calendar $calendar,
 								array $calendarInfo,
 								CalDavBackend $backend) {
@@ -177,4 +179,59 @@ class CalendarImpl implements ICreateFromString {
 			fclose($stream);
 		}
 	}
+
+	/**
+	 * @throws CalendarException
+	 */
+	public function handleIMipMessage(string $name, string $calendarData): void {
+		$server = new InvitationResponseServer(false);
+
+		/** @var CustomPrincipalPlugin $plugin */
+		$plugin = $server->server->getPlugin('auth');
+		// we're working around the previous implementation
+		// that only allowed the public system principal to be used
+		// so set the custom principal here
+		$plugin->setCurrentPrincipal($this->calendar->getPrincipalURI());
+
+		if (empty($this->calendarInfo['uri'])) {
+			throw new CalendarException('Could not write to calendar as URI parameter is missing');
+		}
+		// Force calendar change URI
+		/** @var Schedule\Plugin $schedulingPlugin */
+		$schedulingPlugin = $server->server->getPlugin('caldav-schedule');
+		// Let sabre handle the rest
+		$iTipMessage = new Message();
+		/** @var VCalendar $vObject */
+		$vObject = Reader::read($calendarData);
+		/** @var VEvent $vEvent */
+		$vEvent = $vObject->{'VEVENT'};
+
+		if($vObject->{'METHOD'} === null) {
+			throw new CalendarException('No Method provided for scheduling data. Could not process message');
+		}
+
+		if(!isset($vEvent->{'ORGANIZER'}) || !isset($vEvent->{'ATTENDEE'})) {
+			throw new CalendarException('Could not process scheduling data, neccessary data missing from ICAL');
+		}
+		$orgaizer = $vEvent->{'ORGANIZER'}->getValue();
+		$attendee = $vEvent->{'ATTENDEE'}->getValue();
+
+		$iTipMessage->method = $vObject->{'METHOD'}->getValue();
+		if($iTipMessage->method === 'REPLY') {
+			if ($server->isExternalAttendee($vEvent->{'ATTENDEE'}->getValue())) {
+				$iTipMessage->recipient = $orgaizer;
+			} else {
+				$iTipMessage->recipient = $attendee;
+			}
+			$iTipMessage->sender = $attendee;
+		} else if($iTipMessage->method === 'CANCEL') {
+			$iTipMessage->recipient = $attendee;
+			$iTipMessage->sender = $orgaizer;
+		}
+		$iTipMessage->uid = isset($vEvent->{'UID'}) ? $vEvent->{'UID'}->getValue() : '';
+		$iTipMessage->component = 'VEVENT';
+		$iTipMessage->sequence = isset($vEvent->{'SEQUENCE'}) ? (int)$vEvent->{'SEQUENCE'}->getValue() : 0;
+		$iTipMessage->message = $vObject;
+		$schedulingPlugin->scheduleLocalDelivery($iTipMessage);
+	}
 }
diff --git a/apps/dav/lib/CalDAV/CalendarProvider.php b/apps/dav/lib/CalDAV/CalendarProvider.php
index f29c601db2d..5779111add3 100644
--- a/apps/dav/lib/CalDAV/CalendarProvider.php
+++ b/apps/dav/lib/CalDAV/CalendarProvider.php
@@ -26,6 +26,7 @@ declare(strict_types=1);
 namespace OCA\DAV\CalDAV;
 
 use OCP\Calendar\ICalendarProvider;
+use OCP\Calendar\ICreateFromString;
 use OCP\IConfig;
 use OCP\IL10N;
 use Psr\Log\LoggerInterface;
diff --git a/apps/dav/tests/unit/CalDAV/CalendarImplTest.php b/apps/dav/tests/unit/CalDAV/CalendarImplTest.php
index af8c056cac7..6842bdadb53 100644
--- a/apps/dav/tests/unit/CalDAV/CalendarImplTest.php
+++ b/apps/dav/tests/unit/CalDAV/CalendarImplTest.php
@@ -25,9 +25,13 @@
  */
 namespace OCA\DAV\Tests\unit\CalDAV;
 
+use OCA\DAV\CalDAV\Auth\CustomPrincipalPlugin;
 use OCA\DAV\CalDAV\CalDavBackend;
 use OCA\DAV\CalDAV\Calendar;
 use OCA\DAV\CalDAV\CalendarImpl;
+use OCA\DAV\CalDAV\InvitationResponse\InvitationResponseServer;
+use OCA\DAV\CalDAV\Schedule\Plugin;
+use PHPUnit\Framework\MockObject\MockObject;
 
 class CalendarImplTest extends \Test\TestCase {
 
@@ -51,6 +55,7 @@ class CalendarImplTest extends \Test\TestCase {
 			'id' => 'fancy_id_123',
 			'{DAV:}displayname' => 'user readable name 123',
 			'{http://apple.com/ns/ical/}calendar-color' => '#AABBCC',
+			'uri' => '/this/is/a/uri'
 		];
 		$this->backend = $this->createMock(CalDavBackend::class);
 
@@ -125,4 +130,78 @@ class CalendarImplTest extends \Test\TestCase {
 
 		$this->assertEquals(31, $this->calendarImpl->getPermissions());
 	}
+
+	public function testHandleImipMessage(): void {
+		$invitationResponseServer = $this->createConfiguredMock(InvitationResponseServer::class, [
+			'server' => $this->createConfiguredMock(CalDavBackend::class, [
+				'getPlugin' => [
+					'auth' => $this->createMock(CustomPrincipalPlugin::class),
+					'schedule' => $this->createMock(Plugin::class)
+				]
+			])
+		]);
+
+		$message = <<<EOF
+BEGIN:VCALENDAR
+PRODID:-//Nextcloud/Nextcloud CalDAV Server//EN
+METHOD:REPLY
+VERSION:2.0
+BEGIN:VEVENT
+ATTENDEE;PARTSTAT=mailto:lewis@stardew-tent-living.com:ACCEPTED
+ORGANIZER:mailto:pierre@generalstore.com
+UID:aUniqueUid
+SEQUENCE:2
+REQUEST-STATUS:2.0;Success
+%sEND:VEVENT
+END:VCALENDAR
+EOF;
+
+		/** @var CustomPrincipalPlugin|MockObject $authPlugin */
+		$authPlugin = $invitationResponseServer->server->getPlugin('auth');
+		$authPlugin->expects(self::once())
+			->method('setPrincipalUri')
+			->with($this->calendar->getPrincipalURI());
+
+		/** @var Plugin|MockObject $schedulingPlugin */
+		$schedulingPlugin = $invitationResponseServer->server->getPlugin('caldav-schedule');
+		$schedulingPlugin->expects(self::once())
+			->method('setPathOfCalendarObjectChange')
+			->with('fullcalendarname');
+	}
+
+	public function testHandleImipMessageNoCalendarUri(): void {
+		$invitationResponseServer = $this->createConfiguredMock(InvitationResponseServer::class, [
+			'server' => $this->createConfiguredMock(CalDavBackend::class, [
+				'getPlugin' => [
+					'auth' => $this->createMock(CustomPrincipalPlugin::class),
+					'schedule' => $this->createMock(Plugin::class)
+				]
+			])
+		]);
+
+		$message = <<<EOF
+BEGIN:VCALENDAR
+PRODID:-//Nextcloud/Nextcloud CalDAV Server//EN
+METHOD:REPLY
+VERSION:2.0
+BEGIN:VEVENT
+ATTENDEE;PARTSTAT=mailto:lewis@stardew-tent-living.com:ACCEPTED
+ORGANIZER:mailto:pierre@generalstore.com
+UID:aUniqueUid
+SEQUENCE:2
+REQUEST-STATUS:2.0;Success
+%sEND:VEVENT
+END:VCALENDAR
+EOF;
+
+		/** @var CustomPrincipalPlugin|MockObject $authPlugin */
+		$authPlugin = $invitationResponseServer->server->getPlugin('auth');
+		$authPlugin->expects(self::once())
+			->method('setPrincipalUri')
+			->with($this->calendar->getPrincipalURI());
+
+		unset($this->calendarInfo['uri']);
+		$this->expectException('CalendarException');
+		$this->calendarImpl->handleIMipMessage('filename.ics', $message);
+	}
 }
diff --git a/lib/private/Calendar/Manager.php b/lib/private/Calendar/Manager.php
index 16e142264aa..f0b8e9fd50d 100644
--- a/lib/private/Calendar/Manager.php
+++ b/lib/private/Calendar/Manager.php
@@ -27,12 +27,19 @@ declare(strict_types=1);
 namespace OC\Calendar;
 
 use OC\AppFramework\Bootstrap\Coordinator;
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\Calendar\Exceptions\CalendarException;
 use OCP\Calendar\ICalendar;
 use OCP\Calendar\ICalendarProvider;
 use OCP\Calendar\ICalendarQuery;
+use OCP\Calendar\ICreateFromString;
 use OCP\Calendar\IManager;
 use Psr\Container\ContainerInterface;
 use Psr\Log\LoggerInterface;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VEvent;
+use Sabre\VObject\Property\VCard\DateTime;
+use Sabre\VObject\Reader;
 use Throwable;
 use function array_map;
 use function array_merge;
@@ -58,12 +65,17 @@ class Manager implements IManager {
 	/** @var LoggerInterface */
 	private $logger;
 
+	private ITimeFactory $timeFactory;
+
+
 	public function __construct(Coordinator $coordinator,
 								ContainerInterface $container,
-								LoggerInterface $logger) {
+								LoggerInterface $logger,
+								ITimeFactory $timeFactory) {
 		$this->coordinator = $coordinator;
 		$this->container = $container;
 		$this->logger = $logger;
+		$this->timeFactory = $timeFactory;
 	}
 
 	/**
@@ -167,6 +179,11 @@ class Manager implements IManager {
 		$this->calendarLoaders = [];
 	}
 
+	/**
+	 * @param string $principalUri
+	 * @param array $calendarUris
+	 * @return ICreateFromString[]
+	 */
 	public function getCalendarsForPrincipal(string $principalUri, array $calendarUris = []): array {
 		$context = $this->coordinator->getRegistrationContext();
 		if ($context === null) {
@@ -198,7 +215,6 @@ class Manager implements IManager {
 		);
 
 		$results = [];
-		/** @var ICalendar $calendar */
 		foreach ($calendars as $calendar) {
 			$r = $calendar->search(
 				$query->getSearchPattern() ?? '',
@@ -219,4 +235,137 @@ class Manager implements IManager {
 	public function newQuery(string $principalUri): ICalendarQuery {
 		return new CalendarQuery($principalUri);
 	}
+
+	/**
+	 * @throws \OCP\DB\Exception
+	 */
+	public function handleIMipReply(string $principalUri, string $sender, string $recipient, string $calendarData): bool {
+		/** @var VCalendar $vObject */
+		$vObject = Reader::read($calendarData);
+		/** @var VEvent $vEvent */
+		$vEvent = $vObject->{'VEVENT'};
+
+		// First, we check if the correct method is passed to us
+		if (strcasecmp('REPLY', $vObject->{'METHOD'}->getValue()) !== 0) {
+			$this->logger->warning('Wrong method provided for processing');
+			return false;
+		}
+
+		// check if mail recipient and organizer are one and the same
+		$organizer = substr($vEvent->{'ORGANIZER'}->getValue(), 7);
+
+		if (strcasecmp($recipient, $organizer) !== 0) {
+			$this->logger->warning('Recipient and ORGANIZER must be identical');
+			return false;
+		}
+
+		//check if the event is in the future
+		/** @var DateTime $eventTime */
+		$eventTime = $vEvent->{'DTSTART'};
+		if ($eventTime->getDateTime()->getTimeStamp() < $this->timeFactory->getTime()) { // this might cause issues with recurrences
+			$this->logger->warning('Only events in the future are processed');
+			return false;
+		}
+
+		$calendars = $this->getCalendarsForPrincipal($principalUri);
+		if (empty($calendars)) {
+			$this->logger->warning('Could not find any calendars for principal ' . $principalUri);
+			return false;
+		}
+
+		$found = null;
+		// if the attendee has been found in at least one calendar event with the UID of the iMIP event
+		// we process it.
+		// Benefit: no attendee lost
+		// Drawback: attendees that have been deleted will still be able to update their partstat
+		foreach ($calendars as $calendar) {
+			// We should not search in writable calendars
+			if ($calendar instanceof ICreateFromString) {
+				$o = $calendar->search($sender, ['ATTENDEE'], ['uid' => $vEvent->{'UID'}->getValue()]);
+				if (!empty($o)) {
+					$found = $calendar;
+					$name = $o[0]['uri'];
+					break;
+				}
+			}
+		}
+
+		if (empty($found)) {
+			$this->logger->info('Event not found in any calendar for principal ' . $principalUri . 'and UID' . $vEvent->{'UID'}->getValue());
+			return false;
+		}
+
+		try {
+			$found->handleIMipMessage($name, $calendarData); // sabre will handle the scheduling behind the scenes
+		} catch (CalendarException $e) {
+			$this->logger->error('Could not update calendar for iMIP processing', ['exception' => $e]);
+			return false;
+		}
+		return true;
+	}
+
+	/**
+	 * @since 25.0.0
+	 * @throws \OCP\DB\Exception
+	 */
+	public function handleIMipCancel(string $principalUri, string $sender, ?string $replyTo, string $recipient, string $calendarData): bool {
+		$vObject = Reader::read($calendarData);
+		/** @var VEvent $vEvent */
+		$vEvent = $vObject->{'VEVENT'};
+
+		// First, we check if the correct method is passed to us
+		if (strcasecmp('CANCEL', $vObject->{'METHOD'}->getValue()) !== 0) {
+			$this->logger->warning('Wrong method provided for processing');
+			return false;
+		}
+
+		$attendee = substr($vEvent->{'ATTENDEE'}->getValue(), 7);
+		if (strcasecmp($recipient, $attendee) !== 0) {
+			$this->logger->warning('Recipient must be an ATTENDEE of this event');
+			return false;
+		}
+
+		// Thirdly, we need to compare the email address the CANCEL is coming from (in Mail)
+		// or the Reply- To Address submitted with the CANCEL email
+		// to the email address in the ORGANIZER.
+		// We don't want to accept a CANCEL request from just anyone
+		$organizer = substr($vEvent->{'ORGANIZER'}->getValue(), 7);
+		if (strcasecmp($sender, $organizer) !== 0 && strcasecmp($replyTo, $organizer) !== 0) {
+			$this->logger->warning('Sender must be the ORGANIZER of this event');
+			return false;
+		}
+
+		$calendars = $this->getCalendarsForPrincipal($principalUri);
+		$found = null;
+		// if the attendee has been found in at least one calendar event with the UID of the iMIP event
+		// we process it.
+		// Benefit: no attendee lost
+		// Drawback: attendees that have been deleted will still be able to update their partstat
+		foreach ($calendars as $calendar) {
+			// We should not search in writable calendars
+			if ($calendar instanceof ICreateFromString) {
+				$o = $calendar->search($recipient, ['ATTENDEE'], ['uid' => $vEvent->{'UID'}->getValue()]);
+				if (!empty($o)) {
+					$found = $calendar;
+					$name = $o[0]['uri'];
+					break;
+				}
+			}
+		}
+
+		if (empty($found)) {
+			$this->logger->info('Event not found in any calendar for principal ' . $principalUri . 'and UID' . $vEvent->{'UID'}->getValue());
+			// this is a safe operation
+			// we can ignore events that have been cancelled but were not in the calendar anyway
+			return true;
+		}
+
+		try {
+			$found->handleIMipMessage($name, $calendarData); // sabre will handle the scheduling behind the scenes
+			return true;
+		} catch (CalendarException $e) {
+			$this->logger->error('Could not update calendar for iMIP processing', ['exception' => $e]);
+			return false;
+		}
+	}
 }
diff --git a/lib/public/Calendar/ICreateFromString.php b/lib/public/Calendar/ICreateFromString.php
index 343405e8ab6..8c4bdd44041 100644
--- a/lib/public/Calendar/ICreateFromString.php
+++ b/lib/public/Calendar/ICreateFromString.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * @copyright 2021 Anna Larch <anna.larch@gmx.net>
  *
@@ -38,4 +40,11 @@ interface ICreateFromString extends ICalendar {
 	 * @throws CalendarException
 	 */
 	public function createFromString(string $name, string $calendarData): void;
+
+	/**
+	 * @since 25.0.0
+	 *
+	 * @throws CalendarException
+	 */
+	public function handleIMipMessage(string $name, string $calendarData): void;
 }
diff --git a/lib/public/Calendar/IManager.php b/lib/public/Calendar/IManager.php
index 7f0eec80910..dd65917d12b 100644
--- a/lib/public/Calendar/IManager.php
+++ b/lib/public/Calendar/IManager.php
@@ -156,4 +156,18 @@ interface IManager {
 	 * @since 23.0.0
 	 */
 	public function newQuery(string $principalUri) : ICalendarQuery;
+
+	/**
+	 * Handle a iMip REPLY message
+	 *
+	 * @since 25.0.0
+	 */
+	public function handleIMipReply(string $principalUri, string $sender, string $recipient, string $calendarData): bool;
+
+	/**
+	 * Handle a iMip CANCEL message
+	 *
+	 * @since 25.0.0
+	 */
+	public function handleIMipCancel(string $principalUri, string $sender, ?string $replyTo, string $recipient, string $calendarData): bool;
 }
diff --git a/tests/lib/Calendar/ManagerTest.php b/tests/lib/Calendar/ManagerTest.php
index a4d9d45fdb2..8b99c21ae41 100644
--- a/tests/lib/Calendar/ManagerTest.php
+++ b/tests/lib/Calendar/ManagerTest.php
@@ -25,10 +25,14 @@ namespace Test\Calendar;
 
 use OC\AppFramework\Bootstrap\Coordinator;
 use OC\Calendar\Manager;
+use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Calendar\ICalendar;
+use OCP\Calendar\ICreateFromString;
 use PHPUnit\Framework\MockObject\MockObject;
 use Psr\Container\ContainerInterface;
 use Psr\Log\LoggerInterface;
+use Sabre\VObject\Document;
+use Sabre\VObject\Reader;
 use Test\TestCase;
 
 class ManagerTest extends TestCase {
@@ -45,17 +49,22 @@ class ManagerTest extends TestCase {
 	/** @var Manager */
 	private $manager;
 
+	/** @var ITimeFactory|ITimeFactory&MockObject|MockObject  */
+	private $time;
+
 	protected function setUp(): void {
 		parent::setUp();
 
 		$this->coordinator = $this->createMock(Coordinator::class);
 		$this->container = $this->createMock(ContainerInterface::class);
 		$this->logger = $this->createMock(LoggerInterface::class);
+		$this->time = $this->createMock(ITimeFactory::class);
 
 		$this->manager = new Manager(
 			$this->coordinator,
 			$this->container,
-			$this->logger
+			$this->logger,
+			$this->time,
 		);
 	}
 
@@ -231,4 +240,370 @@ class ManagerTest extends TestCase {
 		$isEnabled = $this->manager->isEnabled();
 		$this->assertTrue($isEnabled);
 	}
+
+	public function testHandleImipReplyWrongMethod(): void {
+		$principalUri = 'principals/user/linus';
+		$sender = 'pierre@general-store.com';
+		$recipient = 'linus@stardew-tent-living.com';
+		$calendarData = $this->getVCalendarReply();
+		$calendarData->METHOD = 'REQUEST';
+
+		$this->logger->expects(self::once())
+			->method('warning');
+		$this->time->expects(self::never())
+			->method('getTimestamp');
+
+		$result = $this->manager->handleIMipReply($principalUri, $sender, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipReplyOrganizerNotRecipient(): void {
+		$principalUri = 'principals/user/linus';
+		$recipient = 'pierre@general-store.com';
+		$sender = 'linus@stardew-tent-living.com';
+		$calendarData = $this->getVCalendarReply();
+
+		$this->logger->expects(self::once())
+			->method('warning');
+		$this->time->expects(self::never())
+			->method('getTimestamp');
+
+		$result = $this->manager->handleIMipReply($principalUri, $sender, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipReplyDateInThePast(): void {
+		$principalUri = 'principals/user/linus';
+		$sender = 'pierre@general-store.com';
+		$recipient = 'linus@stardew-tent-living.com';
+		$calendarData = $this->getVCalendarReply();
+		$calendarData->VEVENT->DTSTART = new \DateTime('2013-04-07'); // set to in the past
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(time());
+
+		$this->logger->expects(self::once())
+			->method('warning');
+
+		$result = $this->manager->handleIMipReply($principalUri, $sender, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipReplyNoCalendars(): void {
+		/** @var Manager | \PHPUnit\Framework\MockObject\MockObject $manager */
+		$manager = $this->getMockBuilder(Manager::class)
+			->setConstructorArgs([
+				$this->coordinator,
+				$this->container,
+				$this->logger,
+				$this->time
+			])
+			->setMethods([
+				'getCalendarsForPrincipal'
+			]);
+		$principalUri = 'principals/user/linus';
+		$sender = 'pierre@general-store.com';
+		$recipient = 'linus@stardew-tent-living.com';
+		$calendarData = $this->getVCalendarReply();
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(202208219);
+		$manager->expects(self::once())
+			->method('getCalendarsForPrincipal')
+			->willReturn([]);
+		$this->logger->expects(self::once())
+			->method('warning');
+
+		$result = $manager->handleIMipReply($principalUri, $sender, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipReplyEventNotFound(): void {
+		/** @var Manager | \PHPUnit\Framework\MockObject\MockObject $manager */
+		$manager = $this->getMockBuilder(Manager::class)
+			->setConstructorArgs([
+				$this->coordinator,
+				$this->container,
+				$this->logger,
+				$this->time
+			])
+			->setMethods([
+				'getCalendarsForPrincipal'
+			]);
+		$calendar = $this->createMock(ICreateFromString::class);
+		$principalUri = 'principals/user/linus';
+		$sender = 'pierre@general-store.com';
+		$recipient = 'linus@stardew-tent-living.com';
+		$calendarData = $this->getVCalendarReply();
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(202208219);
+		$manager->expects(self::once())
+			->method('getCalendarsForPrincipal')
+			->willReturn([$calendar]);
+		$calendar->expects(self::once())
+			->method('search')
+			->willReturn([]);
+		$this->logger->expects(self::once())
+			->method('info');
+		$calendar->expects(self::never())
+			->method('handleIMipMessage');
+
+		$result = $manager->handleIMipReply($principalUri, $sender, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipReply(): void {
+		/** @var Manager | \PHPUnit\Framework\MockObject\MockObject $manager */
+		$manager = $this->getMockBuilder(Manager::class)
+			->setConstructorArgs([
+				$this->coordinator,
+				$this->container,
+				$this->logger,
+				$this->time
+			])
+			->setMethods([
+				'getCalendarsForPrincipal'
+			]);
+		$calendar = $this->createMock(ICreateFromString::class);
+		$principalUri = 'principals/user/linus';
+		$sender = 'pierre@general-store.com';
+		$recipient = 'linus@stardew-tent-living.com';
+		$calendarData = $this->getVCalendarReply();
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(202208219);
+		$manager->expects(self::once())
+			->method('getCalendarsForPrincipal')
+			->willReturn([$calendar]);
+		$calendar->expects(self::once())
+			->method('search')
+			->willReturn([['uri' => 'testname.ics']]);
+		$calendar->expects(self::once())
+			->method('handleIMipMessage')
+			->with('testname.ics', $calendarData->serialize());
+
+		$result = $manager->handleIMipReply($principalUri, $sender, $recipient, $calendarData->serialize());
+		$this->assertTrue($result);
+	}
+
+	public function testHandleImipCancelWrongMethod(): void {
+		$principalUri = 'principals/user/pierre';
+		$sender = 'linus@stardew-tent-living.com';
+		$recipient = 'pierre@general-store.com';
+		$replyTo = null;
+		$calendarData = $this->getVCalendarCancel();
+		$calendarData->VEVENT->METHOD = 'REQUEST';
+
+		$this->logger->expects(self::once())
+			->method('warning');
+		$this->time->expects(self::never())
+			->method('getTimestamp');
+
+		$result = $this->manager->handleIMipCancel($principalUri, $sender, $replyTo, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipCancelAttendeeNotRecipient(): void {
+		$principalUri = '/user/admin';
+		$sender = 'linus@stardew-tent-living.com';
+		$recipient = 'leah@general-store.com';
+		$replyTo = null;
+		$calendarData = $this->getVCalendarCancel();
+		$calendarData->VEVENT->METHOD = 'CANCEL';
+
+		$this->logger->expects(self::once())
+			->method('warning');
+		$this->time->expects(self::never())
+			->method('getTimestamp');
+
+		$result = $this->manager->handleIMipCancel($principalUri, $sender, $replyTo, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipCancelDateInThePast(): void {
+		$principalUri = 'principals/user/pierre';
+		$sender = 'linus@stardew-tent-living.com';
+		$recipient = 'pierre@general-store.com';
+		$replyTo = null;
+		$calendarData = $this->getVCalendarCancel();
+		$calendarData->VEVENT->DTSTART = new \DateTime('2013-04-07'); // set to in the past
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(time());
+		$this->logger->expects(self::once())
+			->method('warning');
+
+		$result = $this->manager->handleIMipCancel($principalUri, $sender, $replyTo, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipCancelNoCalendars(): void {
+		/** @var Manager | \PHPUnit\Framework\MockObject\MockObject $manager */
+		$manager = $this->getMockBuilder(Manager::class)
+			->setConstructorArgs([
+				$this->coordinator,
+				$this->container,
+				$this->logger,
+				$this->time
+			])
+			->setMethods([
+				'getCalendarsForPrincipal'
+			]);
+		$principalUri = 'principals/user/pierre';
+		$sender = 'linus@stardew-tent-living.com';
+		$recipient = 'pierre@general-store.com';
+		$replyTo = null;
+		$calendarData = $this->getVCalendarCancel();
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(202208219);
+		$manager->expects(self::once())
+			->method('getCalendarsForPrincipal')
+			->with($principalUri)
+			->willReturn([]);
+		$this->logger->expects(self::once())
+			->method('warning');
+
+		$result = $this->manager->handleIMipCancel($principalUri, $sender, $replyTo, $recipient, $calendarData->serialize());
+		$this->assertTrue($result);
+	}
+
+	public function testHandleImipCancelOrganiserInReplyTo(): void {
+		/** @var Manager | \PHPUnit\Framework\MockObject\MockObject $manager */
+		$manager = $this->getMockBuilder(Manager::class)
+			->setConstructorArgs([
+				$this->coordinator,
+				$this->container,
+				$this->logger,
+				$this->time
+			])
+			->setMethods([
+				'getCalendarsForPrincipal'
+			]);
+		$principalUri = 'principals/user/pierre';
+		$sender = 'clint@stardew-blacksmiths.com';
+		$recipient = 'pierre@general-store.com';
+		$replyTo = 'linus@stardew-tent-living.com';
+		$calendar = $this->createMock(ICreateFromString::class);
+		$calendarData = $this->getVCalendarCancel();
+		$calendarData->VEVENT->METHOD = 'CANCEL';
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(202208219);
+		$manager->expects(self::once())
+			->method('getCalendarsForPrincipal')
+			->with($principalUri)
+			->willReturn([$calendar]);
+		$calendar->expects(self::once())
+			->method('search')
+			->willReturn([['uri' => 'testname.ics']]);
+		$calendar->expects(self::once())
+			->method('handleIMipMessage')
+			->with('testname.ics', $calendarData->serialize());
+		$result = $this->manager->handleIMipCancel($principalUri, $sender, $replyTo, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	public function testHandleImipCancel(): void {
+		/** @var Manager | \PHPUnit\Framework\MockObject\MockObject $manager */
+		$manager = $this->getMockBuilder(Manager::class)
+			->setConstructorArgs([
+				$this->coordinator,
+				$this->container,
+				$this->logger,
+				$this->time
+			])
+			->setMethods([
+				'getCalendarsForPrincipal'
+			]);
+		$principalUri = 'principals/user/pierre';
+		$sender = 'linus@stardew-tent-living.com';
+		$recipient = 'pierre@general-store.com';
+		$replyTo = null;
+		$calendar = $this->createMock(ICreateFromString::class);
+		$calendarData = $this->getVCalendarCancel();
+		$calendarData->VEVENT->METHOD = 'CANCEL';
+
+		$this->time->expects(self::once())
+			->method('getTimestamp')
+			->willReturn(202208219);
+		$manager->expects(self::once())
+			->method('getCalendarsForPrincipal')
+			->with($principalUri)
+			->willReturn([$calendar]);
+		$calendar->expects(self::once())
+			->method('search')
+			->willReturn([['uri' => 'testname.ics']]);
+		$calendar->expects(self::once())
+			->method('handleIMipMessage')
+			->with('testname.ics', $calendarData->serialize());
+		$result = $this->manager->handleIMipCancel($principalUri, $sender, $replyTo, $recipient, $calendarData->serialize());
+		$this->assertFalse($result);
+	}
+
+	private function getVCalendarReply(): Document {
+		$data = <<<EOF
+BEGIN:VCALENDAR
+PRODID:-//Nextcloud/Nextcloud CalDAV Server//EN
+VERSION:2.0
+CALSCALE:GREGORIAN
+METHOD:REPLY
+BEGIN:VEVENT
+DTSTART;VALUE=DATE:20210820
+DTEND;VALUE=DATE:20220821
+DTSTAMP:20210812T100040Z
+ORGANIZER;CN=admin:mailto:linus@stardew-tent-living.com
+UID:dcc733bf-b2b2-41f2-a8cf-550ae4b67aff
+ATTENDEE;CUTYPE=INDIVIDUAL;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;CN=pierr
+ e@general-store.com;X-NUM-GUESTS=0:mailto:pierre@general-store.com
+CREATED:20220812T100021Z
+DESCRIPTION:
+LAST-MODIFIED:20220812T100040Z
+LOCATION:
+SEQUENCE:3
+STATUS:CONFIRMED
+SUMMARY:berry basket
+TRANSP:OPAQUE
+END:VEVENT
+END:VCALENDAR
+EOF;
+		return Reader::read($data);
+	}
+
+	private function getVCalendarCancel(): Document {
+		$data = <<<EOF
+BEGIN:VCALENDAR
+PRODID:-//Nextcloud/Nextcloud CalDAV Server//EN
+VERSION:2.0
+CALSCALE:GREGORIAN
+METHOD:CANCEL
+BEGIN:VEVENT
+DTSTART;VALUE=DATE:20210820
+DTEND;VALUE=DATE:20220821
+DTSTAMP:20210812T100040Z
+ORGANIZER;CN=admin:mailto:linus@stardew-tent-living.com
+UID:dcc733bf-b2b2-41f2-a8cf-550ae4b67aff
+ATTENDEE;CUTYPE=INDIVIDUAL;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;CN=pierr
+ e@general-store.com;X-NUM-GUESTS=0:mailto:pierre@general-store.com
+CREATED:20220812T100021Z
+DESCRIPTION:
+LAST-MODIFIED:20220812T100040Z
+LOCATION:
+SEQUENCE:3
+STATUS:CANCELLED
+SUMMARY:berry basket
+TRANSP:OPAQUE
+END:VEVENT
+END:VCALENDAR
+EOF;
+		return Reader::read($data);
+	}
 }