nextcloud / server

apps/federatedfilesharing/lib/ocm/CloudFederationProviderFiles.php

Indentation +785 added lines, -785 removed lines

@@ -52,789 +52,789 @@
 
 class CloudFederationProviderFiles implements ICloudFederationProvider {
 
-	/** @var IAppManager */
-	private $appManager;
-
-	/** @var FederatedShareProvider */
-	private $federatedShareProvider;
-
-	/** @var AddressHandler */
-	private $addressHandler;
-
-	/** @var ILogger */
-	private $logger;
-
-	/** @var IUserManager */
-	private $userManager;
-
-	/** @var ICloudIdManager */
-	private $cloudIdManager;
-
-	/** @var IActivityManager */
-	private $activityManager;
-
-	/** @var INotificationManager */
-	private $notificationManager;
-
-	/** @var IURLGenerator */
-	private $urlGenerator;
-
-	/** @var ICloudFederationFactory */
-	private $cloudFederationFactory;
-
-	/** @var ICloudFederationProviderManager */
-	private $cloudFederationProviderManager;
-
-	/** @var IDBConnection */
-	private $connection;
-
-	/** @var IGroupManager */
-	private $groupManager;
-
-	/**
-	 * CloudFederationProvider constructor.
-	 *
-	 * @param IAppManager $appManager
-	 * @param FederatedShareProvider $federatedShareProvider
-	 * @param AddressHandler $addressHandler
-	 * @param ILogger $logger
-	 * @param IUserManager $userManager
-	 * @param ICloudIdManager $cloudIdManager
-	 * @param IActivityManager $activityManager
-	 * @param INotificationManager $notificationManager
-	 * @param IURLGenerator $urlGenerator
-	 * @param ICloudFederationFactory $cloudFederationFactory
-	 * @param ICloudFederationProviderManager $cloudFederationProviderManager
-	 * @param IDBConnection $connection
-	 * @param IGroupManager $groupManager
-	 */
-	public function __construct(IAppManager $appManager,
-								FederatedShareProvider $federatedShareProvider,
-								AddressHandler $addressHandler,
-								ILogger $logger,
-								IUserManager $userManager,
-								ICloudIdManager $cloudIdManager,
-								IActivityManager $activityManager,
-								INotificationManager $notificationManager,
-								IURLGenerator $urlGenerator,
-								ICloudFederationFactory $cloudFederationFactory,
-								ICloudFederationProviderManager $cloudFederationProviderManager,
-								IDBConnection $connection,
-								IGroupManager $groupManager
-	) {
-		$this->appManager = $appManager;
-		$this->federatedShareProvider = $federatedShareProvider;
-		$this->addressHandler = $addressHandler;
-		$this->logger = $logger;
-		$this->userManager = $userManager;
-		$this->cloudIdManager = $cloudIdManager;
-		$this->activityManager = $activityManager;
-		$this->notificationManager = $notificationManager;
-		$this->urlGenerator = $urlGenerator;
-		$this->cloudFederationFactory = $cloudFederationFactory;
-		$this->cloudFederationProviderManager = $cloudFederationProviderManager;
-		$this->connection = $connection;
-		$this->groupManager = $groupManager;
-	}
-
-
-
-	/**
-	 * @return string
-	 */
-	public function getShareType() {
-		return 'file';
-	}
-
-	/**
-	 * share received from another server
-	 *
-	 * @param ICloudFederationShare $share
-	 * @return string provider specific unique ID of the share
-	 *
-	 * @throws ProviderCouldNotAddShareException
-	 * @throws \OCP\AppFramework\QueryException
-	 * @throws \OC\HintException
-	 * @since 14.0.0
-	 */
-	public function shareReceived(ICloudFederationShare $share) {
-
-		if (!$this->isS2SEnabled(true)) {
-			throw new ProviderCouldNotAddShareException('Server does not support federated cloud sharing', '', Http::STATUS_SERVICE_UNAVAILABLE);
-		}
-
-		$protocol = $share->getProtocol();
-		if ($protocol['name'] !== 'webdav') {
-			throw new ProviderCouldNotAddShareException('Unsupported protocol for data exchange.', '', Http::STATUS_NOT_IMPLEMENTED);
-		}
-
-		list($ownerUid, $remote) = $this->addressHandler->splitUserRemote($share->getOwner());
-		// for backward compatibility make sure that the remote url stored in the
-		// database ends with a trailing slash
-		if (substr($remote, -1) !== '/') {
-			$remote = $remote . '/';
-		}
-
-		$token = $share->getShareSecret();
-		$name = $share->getResourceName();
-		$owner = $share->getOwnerDisplayName();
-		$sharedBy = $share->getSharedByDisplayName();
-		$shareWith = $share->getShareWith();
-		$remoteId = $share->getProviderId();
-		$sharedByFederatedId = $share->getSharedBy();
-		$ownerFederatedId = $share->getOwner();
-		$shareType = $this->mapShareTypeToNextcloud($share->getShareType());
-
-		// if no explicit information about the person who created the share was send
-		// we assume that the share comes from the owner
-		if ($sharedByFederatedId === null) {
-			$sharedBy = $owner;
-			$sharedByFederatedId = $ownerFederatedId;
-		}
-
-		if ($remote && $token && $name && $owner && $remoteId && $shareWith) {
-
-			if (!Util::isValidFileName($name)) {
-				throw new ProviderCouldNotAddShareException('The mountpoint name contains invalid characters.', '', Http::STATUS_BAD_REQUEST);
-			}
-
-			// FIXME this should be a method in the user management instead
-			if ($shareType === Share::SHARE_TYPE_USER) {
-				$this->logger->debug('shareWith before, ' . $shareWith, ['app' => 'files_sharing']);
-				Util::emitHook(
-					'\OCA\Files_Sharing\API\Server2Server',
-					'preLoginNameUsedAsUserName',
-					array('uid' => &$shareWith)
-				);
-				$this->logger->debug('shareWith after, ' . $shareWith, ['app' => 'files_sharing']);
-
-				if (!$this->userManager->userExists($shareWith)) {
-					throw new ProviderCouldNotAddShareException('User does not exists', '',Http::STATUS_BAD_REQUEST);
-				}
-
-				\OC_Util::setupFS($shareWith);
-			}
-
-			if ($shareType === Share::SHARE_TYPE_GROUP && !$this->groupManager->groupExists($shareWith)) {
-				throw new ProviderCouldNotAddShareException('Group does not exists', '',Http::STATUS_BAD_REQUEST);
-			}
-
-			$externalManager = new \OCA\Files_Sharing\External\Manager(
-				\OC::$server->getDatabaseConnection(),
-				Filesystem::getMountManager(),
-				Filesystem::getLoader(),
-				\OC::$server->getHTTPClientService(),
-				\OC::$server->getNotificationManager(),
-				\OC::$server->query(\OCP\OCS\IDiscoveryService::class),
-				\OC::$server->getCloudFederationProviderManager(),
-				\OC::$server->getCloudFederationFactory(),
-				\OC::$server->getGroupManager(),
-				\OC::$server->getUserManager(),
-				$shareWith
-			);
-
-			try {
-				$externalManager->addShare($remote, $token, '', $name, $owner, $shareType,false, $shareWith, $remoteId);
-				$shareId = \OC::$server->getDatabaseConnection()->lastInsertId('*PREFIX*share_external');
-
-				if ($shareType === Share::SHARE_TYPE_USER) {
-					$event = $this->activityManager->generateEvent();
-					$event->setApp('files_sharing')
-						->setType('remote_share')
-						->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_RECEIVED, [$ownerFederatedId, trim($name, '/')])
-						->setAffectedUser($shareWith)
-						->setObject('remote_share', (int)$shareId, $name);
-					\OC::$server->getActivityManager()->publish($event);
-					$this->notifyAboutNewShare($shareWith, $shareId, $ownerFederatedId, $sharedByFederatedId, $name);
-				} else {
-					$groupMembers = $this->groupManager->get($shareWith)->getUsers();
-					foreach ($groupMembers as $user) {
-						$event = $this->activityManager->generateEvent();
-						$event->setApp('files_sharing')
-							->setType('remote_share')
-							->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_RECEIVED, [$ownerFederatedId, trim($name, '/')])
-							->setAffectedUser($user->getUID())
-							->setObject('remote_share', (int)$shareId, $name);
-						\OC::$server->getActivityManager()->publish($event);
-						$this->notifyAboutNewShare($user->getUID(), $shareId, $ownerFederatedId, $sharedByFederatedId, $name);
-					}
-				}
-				return $shareId;
-			} catch (\Exception $e) {
-				$this->logger->logException($e, [
-					'message' => 'Server can not add remote share.',
-					'level' => ILogger::ERROR,
-					'app' => 'files_sharing'
-				]);
-				throw new ProviderCouldNotAddShareException('internal server error, was not able to add share from ' . $remote, '', HTTP::STATUS_INTERNAL_SERVER_ERROR);
-			}
-		}
-
-		throw new ProviderCouldNotAddShareException('server can not add remote share, missing parameter', '', HTTP::STATUS_BAD_REQUEST);
-
-	}
-
-	/**
-	 * notification received from another server
-	 *
-	 * @param string $notificationType (e.g. SHARE_ACCEPTED)
-	 * @param string $providerId id of the share
-	 * @param array $notification payload of the notification
-	 * @return array data send back to the sender
-	 *
-	 * @throws ActionNotSupportedException
-	 * @throws AuthenticationFailedException
-	 * @throws BadRequestException
-	 * @throws \OC\HintException
-	 * @since 14.0.0
-	 */
-	public function notificationReceived($notificationType, $providerId, array $notification) {
-
-		switch ($notificationType) {
-			case 'SHARE_ACCEPTED':
-				return $this->shareAccepted($providerId, $notification);
-			case 'SHARE_DECLINED':
-				return $this->shareDeclined($providerId, $notification);
-			case 'SHARE_UNSHARED':
-				return $this->unshare($providerId, $notification);
-			case 'REQUEST_RESHARE':
-				return $this->reshareRequested($providerId, $notification);
-			case 'RESHARE_UNDO':
-				return $this->undoReshare($providerId, $notification);
-			case 'RESHARE_CHANGE_PERMISSION':
-				return $this->updateResharePermissions($providerId, $notification);
-		}
-
-
-		throw new BadRequestException([$notificationType]);
-	}
-
-	/**
-	 * map OCM share type (strings) to Nextcloud internal share types (integer)
-	 *
-	 * @param string $shareType
-	 * @return int
-	 */
-	private function mapShareTypeToNextcloud($shareType) {
-		$result = Share::SHARE_TYPE_USER;
-		if ($shareType === 'group') {
-			$result = Share::SHARE_TYPE_GROUP;
-		}
-
-		return $result;
-	}
-
-	/**
-	 * notify user about new federated share
-	 *
-	 * @param $shareWith
-	 * @param $shareId
-	 * @param $ownerFederatedId
-	 * @param $sharedByFederatedId
-	 * @param $name
-	 */
-	private function notifyAboutNewShare($shareWith, $shareId, $ownerFederatedId, $sharedByFederatedId, $name) {
-		$notification = $this->notificationManager->createNotification();
-		$notification->setApp('files_sharing')
-			->setUser($shareWith)
-			->setDateTime(new \DateTime())
-			->setObject('remote_share', $shareId)
-			->setSubject('remote_share', [$ownerFederatedId, $sharedByFederatedId, trim($name, '/')]);
-
-		$declineAction = $notification->createAction();
-		$declineAction->setLabel('decline')
-			->setLink($this->urlGenerator->getAbsoluteURL($this->urlGenerator->linkTo('', 'ocs/v2.php/apps/files_sharing/api/v1/remote_shares/pending/' . $shareId)), 'DELETE');
-		$notification->addAction($declineAction);
-
-		$acceptAction = $notification->createAction();
-		$acceptAction->setLabel('accept')
-			->setLink($this->urlGenerator->getAbsoluteURL($this->urlGenerator->linkTo('', 'ocs/v2.php/apps/files_sharing/api/v1/remote_shares/pending/' . $shareId)), 'POST');
-		$notification->addAction($acceptAction);
-
-		$this->notificationManager->notify($notification);
-	}
-
-	/**
-	 * process notification that the recipient accepted a share
-	 *
-	 * @param string $id
-	 * @param array $notification
-	 * @return array
-	 * @throws ActionNotSupportedException
-	 * @throws AuthenticationFailedException
-	 * @throws BadRequestException
-	 * @throws \OC\HintException
-	 */
-	private function shareAccepted($id, array $notification) {
-
-		if (!$this->isS2SEnabled()) {
-			throw new ActionNotSupportedException('Server does not support federated cloud sharing');
-		}
-
-		if (!isset($notification['sharedSecret'])) {
-			throw new BadRequestException(['sharedSecret']);
-		}
-
-		$token = $notification['sharedSecret'];
-
-		$share = $this->federatedShareProvider->getShareById($id);
-
-		$this->verifyShare($share, $token);
-		$this->executeAcceptShare($share);
-		if ($share->getShareOwner() !== $share->getSharedBy()) {
-			list(, $remote) = $this->addressHandler->splitUserRemote($share->getSharedBy());
-			$remoteId = $this->federatedShareProvider->getRemoteId($share);
-			$notification = $this->cloudFederationFactory->getCloudFederationNotification();
-			$notification->setMessage(
-				'SHARE_ACCEPTED',
-				'file',
-				$remoteId,
-				[
-					'sharedSecret' => $token,
-					'message' => 'Recipient accepted the re-share'
-				]
-
-			);
-			$this->cloudFederationProviderManager->sendNotification($remote, $notification);
-
-		}
-
-		return [];
-	}
-
-	/**
-	 * @param IShare $share
-	 * @throws ShareNotFound
-	 */
-	protected function executeAcceptShare(IShare $share) {
-		try {
-			$fileId = (int)$share->getNode()->getId();
-			list($file, $link) = $this->getFile($this->getCorrectUid($share), $fileId);
-		} catch (\Exception $e) {
-			throw new ShareNotFound();
-		}
-
-		$event = $this->activityManager->generateEvent();
-		$event->setApp('files_sharing')
-			->setType('remote_share')
-			->setAffectedUser($this->getCorrectUid($share))
-			->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_ACCEPTED, [$share->getSharedWith(), [$fileId => $file]])
-			->setObject('files', $fileId, $file)
-			->setLink($link);
-		$this->activityManager->publish($event);
-	}
-
-	/**
-	 * process notification that the recipient declined a share
-	 *
-	 * @param string $id
-	 * @param array $notification
-	 * @return array
-	 * @throws ActionNotSupportedException
-	 * @throws AuthenticationFailedException
-	 * @throws BadRequestException
-	 * @throws ShareNotFound
-	 * @throws \OC\HintException
-	 *
-	 */
-	protected function shareDeclined($id, array $notification) {
-
-		if (!$this->isS2SEnabled()) {
-			throw new ActionNotSupportedException('Server does not support federated cloud sharing');
-		}
-
-		if (!isset($notification['sharedSecret'])) {
-			throw new BadRequestException(['sharedSecret']);
-		}
-
-		$token = $notification['sharedSecret'];
-
-		$share = $this->federatedShareProvider->getShareById($id);
-
-		$this->verifyShare($share, $token);
-
-		if ($share->getShareOwner() !== $share->getSharedBy()) {
-			list(, $remote) = $this->addressHandler->splitUserRemote($share->getSharedBy());
-			$remoteId = $this->federatedShareProvider->getRemoteId($share);
-			$notification = $this->cloudFederationFactory->getCloudFederationNotification();
-			$notification->setMessage(
-				'SHARE_DECLINED',
-				'file',
-				$remoteId,
-				[
-					'sharedSecret' => $token,
-					'message' => 'Recipient declined the re-share'
-				]
-
-			);
-			$this->cloudFederationProviderManager->sendNotification($remote, $notification);
-		}
-
-		$this->executeDeclineShare($share);
-
-		return [];
-
-	}
-
-	/**
-	 * delete declined share and create a activity
-	 *
-	 * @param IShare $share
-	 * @throws ShareNotFound
-	 */
-	protected function executeDeclineShare(IShare $share) {
-		$this->federatedShareProvider->removeShareFromTable($share);
-
-		try {
-			$fileId = (int)$share->getNode()->getId();
-			list($file, $link) = $this->getFile($this->getCorrectUid($share), $fileId);
-		} catch (\Exception $e) {
-			throw new ShareNotFound();
-		}
-
-		$event = $this->activityManager->generateEvent();
-		$event->setApp('files_sharing')
-			->setType('remote_share')
-			->setAffectedUser($this->getCorrectUid($share))
-			->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_DECLINED, [$share->getSharedWith(), [$fileId => $file]])
-			->setObject('files', $fileId, $file)
-			->setLink($link);
-		$this->activityManager->publish($event);
-
-	}
-
-	/**
-	 * received the notification that the owner unshared a file from you
-	 *
-	 * @param string $id
-	 * @param array $notification
-	 * @return array
-	 * @throws AuthenticationFailedException
-	 * @throws BadRequestException
-	 */
-	private function undoReshare($id, array $notification) {
-		if (!isset($notification['sharedSecret'])) {
-			throw new BadRequestException(['sharedSecret']);
-		}
-		$token = $notification['sharedSecret'];
-
-		$share = $this->federatedShareProvider->getShareById($id);
-
-		$this->verifyShare($share, $token);
-		$this->federatedShareProvider->removeShareFromTable($share);
-		return [];
-	}
-
-	/**
-	 * unshare file from self
-	 *
-	 * @param string $id
-	 * @param array $notification
-	 * @return array
-	 * @throws ActionNotSupportedException
-	 * @throws BadRequestException
-	 */
-	private function unshare($id, array $notification) {
-
-		if (!$this->isS2SEnabled(true)) {
-			throw new ActionNotSupportedException("incoming shares disabled!");
-		}
-
-		if (!isset($notification['sharedSecret'])) {
-			throw new BadRequestException(['sharedSecret']);
-		}
-		$token = $notification['sharedSecret'];
-
-		$qb = $this->connection->getQueryBuilder();
-		$qb->select('*')
-			->from('share_external')
-			->where(
-				$qb->expr()->andX(
-					$qb->expr()->eq('remote_id', $qb->createNamedParameter($id)),
-					$qb->expr()->eq('share_token', $qb->createNamedParameter($token))
-				)
-			);
-
-		$result = $qb->execute();
-		$share = $result->fetch();
-		$result->closeCursor();
-
-		if ($token && $id && !empty($share)) {
-
-			$remote = $this->cleanupRemote($share['remote']);
-
-			$owner = $this->cloudIdManager->getCloudId($share['owner'], $remote);
-			$mountpoint = $share['mountpoint'];
-			$user = $share['user'];
-
-			$qb = $this->connection->getQueryBuilder();
-			$qb->delete('share_external')
-				->where(
-					$qb->expr()->andX(
-						$qb->expr()->eq('remote_id', $qb->createNamedParameter($id)),
-						$qb->expr()->eq('share_token', $qb->createNamedParameter($token))
-					)
-				);
-
-			$qb->execute();
-
-			// delete all child in case of a group share
-			$qb = $this->connection->getQueryBuilder();
-			$qb->delete('share_external')
-				->where($qb->expr()->eq('parent', $qb->createNamedParameter((int)$share['id'])));
-			$qb->execute();
-
-			if ((int)$share['share_type'] === Share::SHARE_TYPE_USER) {
-				if ($share['accepted']) {
-					$path = trim($mountpoint, '/');
-				} else {
-					$path = trim($share['name'], '/');
-				}
-				$notification = $this->notificationManager->createNotification();
-				$notification->setApp('files_sharing')
-					->setUser($share['user'])
-					->setObject('remote_share', (int)$share['id']);
-				$this->notificationManager->markProcessed($notification);
-
-				$event = $this->activityManager->generateEvent();
-				$event->setApp('files_sharing')
-					->setType('remote_share')
-					->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_UNSHARED, [$owner->getId(), $path])
-					->setAffectedUser($user)
-					->setObject('remote_share', (int)$share['id'], $path);
-				\OC::$server->getActivityManager()->publish($event);
-			}
-		}
-
-		return [];
-	}
-
-	private function cleanupRemote($remote) {
-		$remote = substr($remote, strpos($remote, '://') + 3);
-
-		return rtrim($remote, '/');
-	}
-
-	/**
-	 * recipient of a share request to re-share the file with another user
-	 *
-	 * @param string $id
-	 * @param array $notification
-	 * @return array
-	 * @throws AuthenticationFailedException
-	 * @throws BadRequestException
-	 * @throws ProviderCouldNotAddShareException
-	 * @throws ShareNotFound
-	 */
-	protected function reshareRequested($id, array $notification) {
-
-		if (!isset($notification['sharedSecret'])) {
-			throw new BadRequestException(['sharedSecret']);
-		}
-		$token = $notification['sharedSecret'];
-
-		if (!isset($notification['shareWith'])) {
-			throw new BadRequestException(['shareWith']);
-		}
-		$shareWith = $notification['shareWith'];
-
-		if (!isset($notification['senderId'])) {
-			throw new BadRequestException(['senderId']);
-		}
-		$senderId = $notification['senderId'];
-
-		$share = $this->federatedShareProvider->getShareById($id);
-		// don't allow to share a file back to the owner
-		try {
-			list($user, $remote) = $this->addressHandler->splitUserRemote($shareWith);
-			$owner = $share->getShareOwner();
-			$currentServer = $this->addressHandler->generateRemoteURL();
-			if ($this->addressHandler->compareAddresses($user, $remote, $owner, $currentServer)) {
-				throw new ProviderCouldNotAddShareException('Resharing back to the owner is not allowed: ' . $id);
-			}
-		} catch (\Exception $e) {
-			throw new ProviderCouldNotAddShareException($e->getMessage());
-		}
-
-		$this->verifyShare($share, $token);
-
-		// check if re-sharing is allowed
-		if ($share->getPermissions() & Constants::PERMISSION_SHARE) {
-			// the recipient of the initial share is now the initiator for the re-share
-			$share->setSharedBy($share->getSharedWith());
-			$share->setSharedWith($shareWith);
-			$result = $this->federatedShareProvider->create($share);
-			$this->federatedShareProvider->storeRemoteId((int)$result->getId(), $senderId);
-			return ['token' => $result->getToken(), 'providerId' => $result->getId()];
-		} else {
-			throw new ProviderCouldNotAddShareException('resharing not allowed for share: ' . $id);
-		}
-
-	}
-
-	/**
-	 * update permission of a re-share so that the share dialog shows the right
-	 * permission if the owner or the sender changes the permission
-	 *
-	 * @param string $id
-	 * @param array $notification
-	 * @return array
-	 * @throws AuthenticationFailedException
-	 * @throws BadRequestException
-	 */
-	protected function updateResharePermissions($id, array $notification) {
-
-		if (!isset($notification['sharedSecret'])) {
-			throw new BadRequestException(['sharedSecret']);
-		}
-		$token = $notification['sharedSecret'];
-
-		if (!isset($notification['permission'])) {
-			throw new BadRequestException(['permission']);
-		}
-		$ocmPermissions = $notification['permission'];
-
-		$share = $this->federatedShareProvider->getShareById($id);
-
-		$ncPermission = $this->ocmPermissions2ncPermissions($ocmPermissions);
-
-		$this->verifyShare($share, $token);
-		$this->updatePermissionsInDatabase($share, $ncPermission);
-
-		return [];
-	}
-
-	/**
-	 * translate OCM Permissions to Nextcloud permissions
-	 *
-	 * @param array $ocmPermissions
-	 * @return int
-	 * @throws BadRequestException
-	 */
-	protected function ocmPermissions2ncPermissions(array $ocmPermissions) {
-		$ncPermissions = 0;
-		foreach($ocmPermissions as $permission) {
-			switch (strtolower($permission)) {
-				case 'read':
-					$ncPermissions += Constants::PERMISSION_READ;
-					break;
-				case 'write':
-					$ncPermissions += Constants::PERMISSION_CREATE + Constants::PERMISSION_UPDATE;
-					break;
-				case 'share':
-					$ncPermissions += Constants::PERMISSION_SHARE;
-					break;
-				default:
-					throw new BadRequestException(['permission']);
-			}
-
-		}
-
-		return $ncPermissions;
-	}
-
-	/**
-	 * update permissions in database
-	 *
-	 * @param IShare $share
-	 * @param int $permissions
-	 */
-	protected function updatePermissionsInDatabase(IShare $share, $permissions) {
-		$query = $this->connection->getQueryBuilder();
-		$query->update('share')
-			->where($query->expr()->eq('id', $query->createNamedParameter($share->getId())))
-			->set('permissions', $query->createNamedParameter($permissions))
-			->execute();
-	}
-
-
-	/**
-	 * get file
-	 *
-	 * @param string $user
-	 * @param int $fileSource
-	 * @return array with internal path of the file and a absolute link to it
-	 */
-	private function getFile($user, $fileSource) {
-		\OC_Util::setupFS($user);
-
-		try {
-			$file = Filesystem::getPath($fileSource);
-		} catch (NotFoundException $e) {
-			$file = null;
-		}
-		$args = Filesystem::is_dir($file) ? array('dir' => $file) : array('dir' => dirname($file), 'scrollto' => $file);
-		$link = Util::linkToAbsolute('files', 'index.php', $args);
-
-		return [$file, $link];
-
-	}
-
-	/**
-	 * check if we are the initiator or the owner of a re-share and return the correct UID
-	 *
-	 * @param IShare $share
-	 * @return string
-	 */
-	protected function getCorrectUid(IShare $share) {
-		if ($this->userManager->userExists($share->getShareOwner())) {
-			return $share->getShareOwner();
-		}
-
-		return $share->getSharedBy();
-	}
-
-
-
-	/**
-	 * check if we got the right share
-	 *
-	 * @param IShare $share
-	 * @param string $token
-	 * @return bool
-	 * @throws AuthenticationFailedException
-	 */
-	protected function verifyShare(IShare $share, $token) {
-		if (
-			$share->getShareType() === FederatedShareProvider::SHARE_TYPE_REMOTE &&
-			$share->getToken() === $token
-		) {
-			return true;
-		}
-
-		throw new AuthenticationFailedException();
-	}
-
-
-
-	/**
-	 * check if server-to-server sharing is enabled
-	 *
-	 * @param bool $incoming
-	 * @return bool
-	 */
-	private function isS2SEnabled($incoming = false) {
-
-		$result = $this->appManager->isEnabledForUser('files_sharing');
-
-		if ($incoming) {
-			$result = $result && $this->federatedShareProvider->isIncomingServer2serverShareEnabled();
-		} else {
-			$result = $result && $this->federatedShareProvider->isOutgoingServer2serverShareEnabled();
-		}
-
-		return $result;
-	}
-
-
-	/**
-	 * get the supported share types, e.g. "user", "group", etc.
-	 *
-	 * @return array
-	 *
-	 * @since 14.0.0
-	 */
-	public function getSupportedShareTypes() {
-		return ['user', 'group'];
-	}
+    /** @var IAppManager */
+    private $appManager;
+
+    /** @var FederatedShareProvider */
+    private $federatedShareProvider;
+
+    /** @var AddressHandler */
+    private $addressHandler;
+
+    /** @var ILogger */
+    private $logger;
+
+    /** @var IUserManager */
+    private $userManager;
+
+    /** @var ICloudIdManager */
+    private $cloudIdManager;
+
+    /** @var IActivityManager */
+    private $activityManager;
+
+    /** @var INotificationManager */
+    private $notificationManager;
+
+    /** @var IURLGenerator */
+    private $urlGenerator;
+
+    /** @var ICloudFederationFactory */
+    private $cloudFederationFactory;
+
+    /** @var ICloudFederationProviderManager */
+    private $cloudFederationProviderManager;
+
+    /** @var IDBConnection */
+    private $connection;
+
+    /** @var IGroupManager */
+    private $groupManager;
+
+    /**
+     * CloudFederationProvider constructor.
+     *
+     * @param IAppManager $appManager
+     * @param FederatedShareProvider $federatedShareProvider
+     * @param AddressHandler $addressHandler
+     * @param ILogger $logger
+     * @param IUserManager $userManager
+     * @param ICloudIdManager $cloudIdManager
+     * @param IActivityManager $activityManager
+     * @param INotificationManager $notificationManager
+     * @param IURLGenerator $urlGenerator
+     * @param ICloudFederationFactory $cloudFederationFactory
+     * @param ICloudFederationProviderManager $cloudFederationProviderManager
+     * @param IDBConnection $connection
+     * @param IGroupManager $groupManager
+     */
+    public function __construct(IAppManager $appManager,
+                                FederatedShareProvider $federatedShareProvider,
+                                AddressHandler $addressHandler,
+                                ILogger $logger,
+                                IUserManager $userManager,
+                                ICloudIdManager $cloudIdManager,
+                                IActivityManager $activityManager,
+                                INotificationManager $notificationManager,
+                                IURLGenerator $urlGenerator,
+                                ICloudFederationFactory $cloudFederationFactory,
+                                ICloudFederationProviderManager $cloudFederationProviderManager,
+                                IDBConnection $connection,
+                                IGroupManager $groupManager
+    ) {
+        $this->appManager = $appManager;
+        $this->federatedShareProvider = $federatedShareProvider;
+        $this->addressHandler = $addressHandler;
+        $this->logger = $logger;
+        $this->userManager = $userManager;
+        $this->cloudIdManager = $cloudIdManager;
+        $this->activityManager = $activityManager;
+        $this->notificationManager = $notificationManager;
+        $this->urlGenerator = $urlGenerator;
+        $this->cloudFederationFactory = $cloudFederationFactory;
+        $this->cloudFederationProviderManager = $cloudFederationProviderManager;
+        $this->connection = $connection;
+        $this->groupManager = $groupManager;
+    }
+
+
+
+    /**
+     * @return string
+     */
+    public function getShareType() {
+        return 'file';
+    }
+
+    /**
+     * share received from another server
+     *
+     * @param ICloudFederationShare $share
+     * @return string provider specific unique ID of the share
+     *
+     * @throws ProviderCouldNotAddShareException
+     * @throws \OCP\AppFramework\QueryException
+     * @throws \OC\HintException
+     * @since 14.0.0
+     */
+    public function shareReceived(ICloudFederationShare $share) {
+
+        if (!$this->isS2SEnabled(true)) {
+            throw new ProviderCouldNotAddShareException('Server does not support federated cloud sharing', '', Http::STATUS_SERVICE_UNAVAILABLE);
+        }
+
+        $protocol = $share->getProtocol();
+        if ($protocol['name'] !== 'webdav') {
+            throw new ProviderCouldNotAddShareException('Unsupported protocol for data exchange.', '', Http::STATUS_NOT_IMPLEMENTED);
+        }
+
+        list($ownerUid, $remote) = $this->addressHandler->splitUserRemote($share->getOwner());
+        // for backward compatibility make sure that the remote url stored in the
+        // database ends with a trailing slash
+        if (substr($remote, -1) !== '/') {
+            $remote = $remote . '/';
+        }
+
+        $token = $share->getShareSecret();
+        $name = $share->getResourceName();
+        $owner = $share->getOwnerDisplayName();
+        $sharedBy = $share->getSharedByDisplayName();
+        $shareWith = $share->getShareWith();
+        $remoteId = $share->getProviderId();
+        $sharedByFederatedId = $share->getSharedBy();
+        $ownerFederatedId = $share->getOwner();
+        $shareType = $this->mapShareTypeToNextcloud($share->getShareType());
+
+        // if no explicit information about the person who created the share was send
+        // we assume that the share comes from the owner
+        if ($sharedByFederatedId === null) {
+            $sharedBy = $owner;
+            $sharedByFederatedId = $ownerFederatedId;
+        }
+
+        if ($remote && $token && $name && $owner && $remoteId && $shareWith) {
+
+            if (!Util::isValidFileName($name)) {
+                throw new ProviderCouldNotAddShareException('The mountpoint name contains invalid characters.', '', Http::STATUS_BAD_REQUEST);
+            }
+
+            // FIXME this should be a method in the user management instead
+            if ($shareType === Share::SHARE_TYPE_USER) {
+                $this->logger->debug('shareWith before, ' . $shareWith, ['app' => 'files_sharing']);
+                Util::emitHook(
+                    '\OCA\Files_Sharing\API\Server2Server',
+                    'preLoginNameUsedAsUserName',
+                    array('uid' => &$shareWith)
+                );
+                $this->logger->debug('shareWith after, ' . $shareWith, ['app' => 'files_sharing']);
+
+                if (!$this->userManager->userExists($shareWith)) {
+                    throw new ProviderCouldNotAddShareException('User does not exists', '',Http::STATUS_BAD_REQUEST);
+                }
+
+                \OC_Util::setupFS($shareWith);
+            }
+
+            if ($shareType === Share::SHARE_TYPE_GROUP && !$this->groupManager->groupExists($shareWith)) {
+                throw new ProviderCouldNotAddShareException('Group does not exists', '',Http::STATUS_BAD_REQUEST);
+            }
+
+            $externalManager = new \OCA\Files_Sharing\External\Manager(
+                \OC::$server->getDatabaseConnection(),
+                Filesystem::getMountManager(),
+                Filesystem::getLoader(),
+                \OC::$server->getHTTPClientService(),
+                \OC::$server->getNotificationManager(),
+                \OC::$server->query(\OCP\OCS\IDiscoveryService::class),
+                \OC::$server->getCloudFederationProviderManager(),
+                \OC::$server->getCloudFederationFactory(),
+                \OC::$server->getGroupManager(),
+                \OC::$server->getUserManager(),
+                $shareWith
+            );
+
+            try {
+                $externalManager->addShare($remote, $token, '', $name, $owner, $shareType,false, $shareWith, $remoteId);
+                $shareId = \OC::$server->getDatabaseConnection()->lastInsertId('*PREFIX*share_external');
+
+                if ($shareType === Share::SHARE_TYPE_USER) {
+                    $event = $this->activityManager->generateEvent();
+                    $event->setApp('files_sharing')
+                        ->setType('remote_share')
+                        ->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_RECEIVED, [$ownerFederatedId, trim($name, '/')])
+                        ->setAffectedUser($shareWith)
+                        ->setObject('remote_share', (int)$shareId, $name);
+                    \OC::$server->getActivityManager()->publish($event);
+                    $this->notifyAboutNewShare($shareWith, $shareId, $ownerFederatedId, $sharedByFederatedId, $name);
+                } else {
+                    $groupMembers = $this->groupManager->get($shareWith)->getUsers();
+                    foreach ($groupMembers as $user) {
+                        $event = $this->activityManager->generateEvent();
+                        $event->setApp('files_sharing')
+                            ->setType('remote_share')
+                            ->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_RECEIVED, [$ownerFederatedId, trim($name, '/')])
+                            ->setAffectedUser($user->getUID())
+                            ->setObject('remote_share', (int)$shareId, $name);
+                        \OC::$server->getActivityManager()->publish($event);
+                        $this->notifyAboutNewShare($user->getUID(), $shareId, $ownerFederatedId, $sharedByFederatedId, $name);
+                    }
+                }
+                return $shareId;
+            } catch (\Exception $e) {
+                $this->logger->logException($e, [
+                    'message' => 'Server can not add remote share.',
+                    'level' => ILogger::ERROR,
+                    'app' => 'files_sharing'
+                ]);
+                throw new ProviderCouldNotAddShareException('internal server error, was not able to add share from ' . $remote, '', HTTP::STATUS_INTERNAL_SERVER_ERROR);
+            }
+        }
+
+        throw new ProviderCouldNotAddShareException('server can not add remote share, missing parameter', '', HTTP::STATUS_BAD_REQUEST);
+
+    }
+
+    /**
+     * notification received from another server
+     *
+     * @param string $notificationType (e.g. SHARE_ACCEPTED)
+     * @param string $providerId id of the share
+     * @param array $notification payload of the notification
+     * @return array data send back to the sender
+     *
+     * @throws ActionNotSupportedException
+     * @throws AuthenticationFailedException
+     * @throws BadRequestException
+     * @throws \OC\HintException
+     * @since 14.0.0
+     */
+    public function notificationReceived($notificationType, $providerId, array $notification) {
+
+        switch ($notificationType) {
+            case 'SHARE_ACCEPTED':
+                return $this->shareAccepted($providerId, $notification);
+            case 'SHARE_DECLINED':
+                return $this->shareDeclined($providerId, $notification);
+            case 'SHARE_UNSHARED':
+                return $this->unshare($providerId, $notification);
+            case 'REQUEST_RESHARE':
+                return $this->reshareRequested($providerId, $notification);
+            case 'RESHARE_UNDO':
+                return $this->undoReshare($providerId, $notification);
+            case 'RESHARE_CHANGE_PERMISSION':
+                return $this->updateResharePermissions($providerId, $notification);
+        }
+
+
+        throw new BadRequestException([$notificationType]);
+    }
+
+    /**
+     * map OCM share type (strings) to Nextcloud internal share types (integer)
+     *
+     * @param string $shareType
+     * @return int
+     */
+    private function mapShareTypeToNextcloud($shareType) {
+        $result = Share::SHARE_TYPE_USER;
+        if ($shareType === 'group') {
+            $result = Share::SHARE_TYPE_GROUP;
+        }
+
+        return $result;
+    }
+
+    /**
+     * notify user about new federated share
+     *
+     * @param $shareWith
+     * @param $shareId
+     * @param $ownerFederatedId
+     * @param $sharedByFederatedId
+     * @param $name
+     */
+    private function notifyAboutNewShare($shareWith, $shareId, $ownerFederatedId, $sharedByFederatedId, $name) {
+        $notification = $this->notificationManager->createNotification();
+        $notification->setApp('files_sharing')
+            ->setUser($shareWith)
+            ->setDateTime(new \DateTime())
+            ->setObject('remote_share', $shareId)
+            ->setSubject('remote_share', [$ownerFederatedId, $sharedByFederatedId, trim($name, '/')]);
+
+        $declineAction = $notification->createAction();
+        $declineAction->setLabel('decline')
+            ->setLink($this->urlGenerator->getAbsoluteURL($this->urlGenerator->linkTo('', 'ocs/v2.php/apps/files_sharing/api/v1/remote_shares/pending/' . $shareId)), 'DELETE');
+        $notification->addAction($declineAction);
+
+        $acceptAction = $notification->createAction();
+        $acceptAction->setLabel('accept')
+            ->setLink($this->urlGenerator->getAbsoluteURL($this->urlGenerator->linkTo('', 'ocs/v2.php/apps/files_sharing/api/v1/remote_shares/pending/' . $shareId)), 'POST');
+        $notification->addAction($acceptAction);
+
+        $this->notificationManager->notify($notification);
+    }
+
+    /**
+     * process notification that the recipient accepted a share
+     *
+     * @param string $id
+     * @param array $notification
+     * @return array
+     * @throws ActionNotSupportedException
+     * @throws AuthenticationFailedException
+     * @throws BadRequestException
+     * @throws \OC\HintException
+     */
+    private function shareAccepted($id, array $notification) {
+
+        if (!$this->isS2SEnabled()) {
+            throw new ActionNotSupportedException('Server does not support federated cloud sharing');
+        }
+
+        if (!isset($notification['sharedSecret'])) {
+            throw new BadRequestException(['sharedSecret']);
+        }
+
+        $token = $notification['sharedSecret'];
+
+        $share = $this->federatedShareProvider->getShareById($id);
+
+        $this->verifyShare($share, $token);
+        $this->executeAcceptShare($share);
+        if ($share->getShareOwner() !== $share->getSharedBy()) {
+            list(, $remote) = $this->addressHandler->splitUserRemote($share->getSharedBy());
+            $remoteId = $this->federatedShareProvider->getRemoteId($share);
+            $notification = $this->cloudFederationFactory->getCloudFederationNotification();
+            $notification->setMessage(
+                'SHARE_ACCEPTED',
+                'file',
+                $remoteId,
+                [
+                    'sharedSecret' => $token,
+                    'message' => 'Recipient accepted the re-share'
+                ]
+
+            );
+            $this->cloudFederationProviderManager->sendNotification($remote, $notification);
+
+        }
+
+        return [];
+    }
+
+    /**
+     * @param IShare $share
+     * @throws ShareNotFound
+     */
+    protected function executeAcceptShare(IShare $share) {
+        try {
+            $fileId = (int)$share->getNode()->getId();
+            list($file, $link) = $this->getFile($this->getCorrectUid($share), $fileId);
+        } catch (\Exception $e) {
+            throw new ShareNotFound();
+        }
+
+        $event = $this->activityManager->generateEvent();
+        $event->setApp('files_sharing')
+            ->setType('remote_share')
+            ->setAffectedUser($this->getCorrectUid($share))
+            ->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_ACCEPTED, [$share->getSharedWith(), [$fileId => $file]])
+            ->setObject('files', $fileId, $file)
+            ->setLink($link);
+        $this->activityManager->publish($event);
+    }
+
+    /**
+     * process notification that the recipient declined a share
+     *
+     * @param string $id
+     * @param array $notification
+     * @return array
+     * @throws ActionNotSupportedException
+     * @throws AuthenticationFailedException
+     * @throws BadRequestException
+     * @throws ShareNotFound
+     * @throws \OC\HintException
+     *
+     */
+    protected function shareDeclined($id, array $notification) {
+
+        if (!$this->isS2SEnabled()) {
+            throw new ActionNotSupportedException('Server does not support federated cloud sharing');
+        }
+
+        if (!isset($notification['sharedSecret'])) {
+            throw new BadRequestException(['sharedSecret']);
+        }
+
+        $token = $notification['sharedSecret'];
+
+        $share = $this->federatedShareProvider->getShareById($id);
+
+        $this->verifyShare($share, $token);
+
+        if ($share->getShareOwner() !== $share->getSharedBy()) {
+            list(, $remote) = $this->addressHandler->splitUserRemote($share->getSharedBy());
+            $remoteId = $this->federatedShareProvider->getRemoteId($share);
+            $notification = $this->cloudFederationFactory->getCloudFederationNotification();
+            $notification->setMessage(
+                'SHARE_DECLINED',
+                'file',
+                $remoteId,
+                [
+                    'sharedSecret' => $token,
+                    'message' => 'Recipient declined the re-share'
+                ]
+
+            );
+            $this->cloudFederationProviderManager->sendNotification($remote, $notification);
+        }
+
+        $this->executeDeclineShare($share);
+
+        return [];
+
+    }
+
+    /**
+     * delete declined share and create a activity
+     *
+     * @param IShare $share
+     * @throws ShareNotFound
+     */
+    protected function executeDeclineShare(IShare $share) {
+        $this->federatedShareProvider->removeShareFromTable($share);
+
+        try {
+            $fileId = (int)$share->getNode()->getId();
+            list($file, $link) = $this->getFile($this->getCorrectUid($share), $fileId);
+        } catch (\Exception $e) {
+            throw new ShareNotFound();
+        }
+
+        $event = $this->activityManager->generateEvent();
+        $event->setApp('files_sharing')
+            ->setType('remote_share')
+            ->setAffectedUser($this->getCorrectUid($share))
+            ->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_DECLINED, [$share->getSharedWith(), [$fileId => $file]])
+            ->setObject('files', $fileId, $file)
+            ->setLink($link);
+        $this->activityManager->publish($event);
+
+    }
+
+    /**
+     * received the notification that the owner unshared a file from you
+     *
+     * @param string $id
+     * @param array $notification
+     * @return array
+     * @throws AuthenticationFailedException
+     * @throws BadRequestException
+     */
+    private function undoReshare($id, array $notification) {
+        if (!isset($notification['sharedSecret'])) {
+            throw new BadRequestException(['sharedSecret']);
+        }
+        $token = $notification['sharedSecret'];
+
+        $share = $this->federatedShareProvider->getShareById($id);
+
+        $this->verifyShare($share, $token);
+        $this->federatedShareProvider->removeShareFromTable($share);
+        return [];
+    }
+
+    /**
+     * unshare file from self
+     *
+     * @param string $id
+     * @param array $notification
+     * @return array
+     * @throws ActionNotSupportedException
+     * @throws BadRequestException
+     */
+    private function unshare($id, array $notification) {
+
+        if (!$this->isS2SEnabled(true)) {
+            throw new ActionNotSupportedException("incoming shares disabled!");
+        }
+
+        if (!isset($notification['sharedSecret'])) {
+            throw new BadRequestException(['sharedSecret']);
+        }
+        $token = $notification['sharedSecret'];
+
+        $qb = $this->connection->getQueryBuilder();
+        $qb->select('*')
+            ->from('share_external')
+            ->where(
+                $qb->expr()->andX(
+                    $qb->expr()->eq('remote_id', $qb->createNamedParameter($id)),
+                    $qb->expr()->eq('share_token', $qb->createNamedParameter($token))
+                )
+            );
+
+        $result = $qb->execute();
+        $share = $result->fetch();
+        $result->closeCursor();
+
+        if ($token && $id && !empty($share)) {
+
+            $remote = $this->cleanupRemote($share['remote']);
+
+            $owner = $this->cloudIdManager->getCloudId($share['owner'], $remote);
+            $mountpoint = $share['mountpoint'];
+            $user = $share['user'];
+
+            $qb = $this->connection->getQueryBuilder();
+            $qb->delete('share_external')
+                ->where(
+                    $qb->expr()->andX(
+                        $qb->expr()->eq('remote_id', $qb->createNamedParameter($id)),
+                        $qb->expr()->eq('share_token', $qb->createNamedParameter($token))
+                    )
+                );
+
+            $qb->execute();
+
+            // delete all child in case of a group share
+            $qb = $this->connection->getQueryBuilder();
+            $qb->delete('share_external')
+                ->where($qb->expr()->eq('parent', $qb->createNamedParameter((int)$share['id'])));
+            $qb->execute();
+
+            if ((int)$share['share_type'] === Share::SHARE_TYPE_USER) {
+                if ($share['accepted']) {
+                    $path = trim($mountpoint, '/');
+                } else {
+                    $path = trim($share['name'], '/');
+                }
+                $notification = $this->notificationManager->createNotification();
+                $notification->setApp('files_sharing')
+                    ->setUser($share['user'])
+                    ->setObject('remote_share', (int)$share['id']);
+                $this->notificationManager->markProcessed($notification);
+
+                $event = $this->activityManager->generateEvent();
+                $event->setApp('files_sharing')
+                    ->setType('remote_share')
+                    ->setSubject(RemoteShares::SUBJECT_REMOTE_SHARE_UNSHARED, [$owner->getId(), $path])
+                    ->setAffectedUser($user)
+                    ->setObject('remote_share', (int)$share['id'], $path);
+                \OC::$server->getActivityManager()->publish($event);
+            }
+        }
+
+        return [];
+    }
+
+    private function cleanupRemote($remote) {
+        $remote = substr($remote, strpos($remote, '://') + 3);
+
+        return rtrim($remote, '/');
+    }
+
+    /**
+     * recipient of a share request to re-share the file with another user
+     *
+     * @param string $id
+     * @param array $notification
+     * @return array
+     * @throws AuthenticationFailedException
+     * @throws BadRequestException
+     * @throws ProviderCouldNotAddShareException
+     * @throws ShareNotFound
+     */
+    protected function reshareRequested($id, array $notification) {
+
+        if (!isset($notification['sharedSecret'])) {
+            throw new BadRequestException(['sharedSecret']);
+        }
+        $token = $notification['sharedSecret'];
+
+        if (!isset($notification['shareWith'])) {
+            throw new BadRequestException(['shareWith']);
+        }
+        $shareWith = $notification['shareWith'];
+
+        if (!isset($notification['senderId'])) {
+            throw new BadRequestException(['senderId']);
+        }
+        $senderId = $notification['senderId'];
+
+        $share = $this->federatedShareProvider->getShareById($id);
+        // don't allow to share a file back to the owner
+        try {
+            list($user, $remote) = $this->addressHandler->splitUserRemote($shareWith);
+            $owner = $share->getShareOwner();
+            $currentServer = $this->addressHandler->generateRemoteURL();
+            if ($this->addressHandler->compareAddresses($user, $remote, $owner, $currentServer)) {
+                throw new ProviderCouldNotAddShareException('Resharing back to the owner is not allowed: ' . $id);
+            }
+        } catch (\Exception $e) {
+            throw new ProviderCouldNotAddShareException($e->getMessage());
+        }
+
+        $this->verifyShare($share, $token);
+
+        // check if re-sharing is allowed
+        if ($share->getPermissions() & Constants::PERMISSION_SHARE) {
+            // the recipient of the initial share is now the initiator for the re-share
+            $share->setSharedBy($share->getSharedWith());
+            $share->setSharedWith($shareWith);
+            $result = $this->federatedShareProvider->create($share);
+            $this->federatedShareProvider->storeRemoteId((int)$result->getId(), $senderId);
+            return ['token' => $result->getToken(), 'providerId' => $result->getId()];
+        } else {
+            throw new ProviderCouldNotAddShareException('resharing not allowed for share: ' . $id);
+        }
+
+    }
+
+    /**
+     * update permission of a re-share so that the share dialog shows the right
+     * permission if the owner or the sender changes the permission
+     *
+     * @param string $id
+     * @param array $notification
+     * @return array
+     * @throws AuthenticationFailedException
+     * @throws BadRequestException
+     */
+    protected function updateResharePermissions($id, array $notification) {
+
+        if (!isset($notification['sharedSecret'])) {
+            throw new BadRequestException(['sharedSecret']);
+        }
+        $token = $notification['sharedSecret'];
+
+        if (!isset($notification['permission'])) {
+            throw new BadRequestException(['permission']);
+        }
+        $ocmPermissions = $notification['permission'];
+
+        $share = $this->federatedShareProvider->getShareById($id);
+
+        $ncPermission = $this->ocmPermissions2ncPermissions($ocmPermissions);
+
+        $this->verifyShare($share, $token);
+        $this->updatePermissionsInDatabase($share, $ncPermission);
+
+        return [];
+    }
+
+    /**
+     * translate OCM Permissions to Nextcloud permissions
+     *
+     * @param array $ocmPermissions
+     * @return int
+     * @throws BadRequestException
+     */
+    protected function ocmPermissions2ncPermissions(array $ocmPermissions) {
+        $ncPermissions = 0;
+        foreach($ocmPermissions as $permission) {
+            switch (strtolower($permission)) {
+                case 'read':
+                    $ncPermissions += Constants::PERMISSION_READ;
+                    break;
+                case 'write':
+                    $ncPermissions += Constants::PERMISSION_CREATE + Constants::PERMISSION_UPDATE;
+                    break;
+                case 'share':
+                    $ncPermissions += Constants::PERMISSION_SHARE;
+                    break;
+                default:
+                    throw new BadRequestException(['permission']);
+            }
+
+        }
+
+        return $ncPermissions;
+    }
+
+    /**
+     * update permissions in database
+     *
+     * @param IShare $share
+     * @param int $permissions
+     */
+    protected function updatePermissionsInDatabase(IShare $share, $permissions) {
+        $query = $this->connection->getQueryBuilder();
+        $query->update('share')
+            ->where($query->expr()->eq('id', $query->createNamedParameter($share->getId())))
+            ->set('permissions', $query->createNamedParameter($permissions))
+            ->execute();
+    }
+
+
+    /**
+     * get file
+     *
+     * @param string $user
+     * @param int $fileSource
+     * @return array with internal path of the file and a absolute link to it
+     */
+    private function getFile($user, $fileSource) {
+        \OC_Util::setupFS($user);
+
+        try {
+            $file = Filesystem::getPath($fileSource);
+        } catch (NotFoundException $e) {
+            $file = null;
+        }
+        $args = Filesystem::is_dir($file) ? array('dir' => $file) : array('dir' => dirname($file), 'scrollto' => $file);
+        $link = Util::linkToAbsolute('files', 'index.php', $args);
+
+        return [$file, $link];
+
+    }
+
+    /**
+     * check if we are the initiator or the owner of a re-share and return the correct UID
+     *
+     * @param IShare $share
+     * @return string
+     */
+    protected function getCorrectUid(IShare $share) {
+        if ($this->userManager->userExists($share->getShareOwner())) {
+            return $share->getShareOwner();
+        }
+
+        return $share->getSharedBy();
+    }
+
+
+
+    /**
+     * check if we got the right share
+     *
+     * @param IShare $share
+     * @param string $token
+     * @return bool
+     * @throws AuthenticationFailedException
+     */
+    protected function verifyShare(IShare $share, $token) {
+        if (
+            $share->getShareType() === FederatedShareProvider::SHARE_TYPE_REMOTE &&
+            $share->getToken() === $token
+        ) {
+            return true;
+        }
+
+        throw new AuthenticationFailedException();
+    }
+
+
+
+    /**
+     * check if server-to-server sharing is enabled
+     *
+     * @param bool $incoming
+     * @return bool
+     */
+    private function isS2SEnabled($incoming = false) {
+
+        $result = $this->appManager->isEnabledForUser('files_sharing');
+
+        if ($incoming) {
+            $result = $result && $this->federatedShareProvider->isIncomingServer2serverShareEnabled();
+        } else {
+            $result = $result && $this->federatedShareProvider->isOutgoingServer2serverShareEnabled();
+        }
+
+        return $result;
+    }
+
+
+    /**
+     * get the supported share types, e.g. "user", "group", etc.
+     *
+     * @return array
+     *
+     * @since 14.0.0
+     */
+    public function getSupportedShareTypes() {
+        return ['user', 'group'];
+    }
 }