sessions: ignore self-emitted update events

Signed-off-by: chandi Langecker <git@chandi.it>

lib/Db/SessionMapper.php

@@ -56,7 +56,7 @@ class SessionMapper extends QBMapper {
 
 	public function findAllActive($boardId) {
 		$qb = $this->db->getQueryBuilder();
-		$qb->select('id', 'board_id', 'last_contact', 'user_id')
+		$qb->select('id', 'board_id', 'last_contact', 'user_id', 'token')
 			->from($this->getTableName())
 			->where($qb->expr()->eq('board_id', $qb->createNamedParameter($boardId)))
 			->andWhere($qb->expr()->gt('last_contact', $qb->createNamedParameter(time() - SessionService::SESSION_VALID_TIME)))

lib/Listeners/LiveUpdateListener.php

@@ -33,25 +33,30 @@ use OCA\Deck\Service\SessionService;
 use OCA\NotifyPush\Queue\IQueue;
 use OCP\EventDispatcher\Event;
 use OCP\EventDispatcher\IEventListener;
+use OCP\IRequest;
 use Psr\Container\ContainerInterface;
 use Psr\Log\LoggerInterface;
 
 class LiveUpdateListener implements IEventListener {
-	private string $userId;
 	private LoggerInterface $logger;
 	private SessionService $sessionService;
+	private IRequest $request;
 	private $queue;
 	
-	public function __construct(ContainerInterface $container, SessionService $sessionService, $userId) {
+	public function __construct(
+		ContainerInterface $container,
+		IRequest $request,
+		SessionService $sessionService
+	) {
 		try {
 			$this->queue = $container->get(IQueue::class);
 		} catch (\Exception $e) {
 			// most likely notify_push is not installed.
 			return;
 		}
-		$this->userId = $userId;
 		$this->logger = $container->get(LoggerInterface::class);
 		$this->sessionService = $sessionService;
+		$this->request = $request;
 	}
 
 	public function handle(Event $event): void {
@@ -61,10 +66,17 @@ class LiveUpdateListener implements IEventListener {
 		}
 
 		try {
-			if ($event instanceof SessionCreatedEvent || $event instanceof SessionClosedEvent) {
+			// the web frontend is adding the Session-ID as a header on every request
-				$this->sessionService->notifyAllSessions($this->queue, $event->getBoardId(), NotifyPushEvents::DeckBoardUpdate, $event->getUserId(), [
+			// TODO: verify the token! this currently allows to spoof a token from someone
+			// else, preventing this person from getting any live updates
+			$causingSessionToken = $this->request->getHeader('x-nc-deck-session');
+			if (
+				$event instanceof SessionCreatedEvent ||
+				$event instanceof SessionClosedEvent
+			) {
+				$this->sessionService->notifyAllSessions($this->queue, $event->getBoardId(), NotifyPushEvents::DeckBoardUpdate, [
 					'id' => $event->getBoardId()
-				]);
+				], $causingSessionToken);
 			}
 		} catch (\Exception $e) {
 			$this->logger->error('Error when handling live update event', ['exception' => $e]);

lib/Service/SessionService.php

@@ -57,11 +57,11 @@ class SessionService {
 		$this->eventDispatcher = $eventDispatcher;
 	}
 
-	public function initSession($boardId): Session {
+	public function initSession(int $boardId): Session {
 		$session = new Session();
 		$session->setBoardId($boardId);
 		$session->setUserId($this->userId);
-		$session->setToken($this->secureRandom->generate(64));
+		$session->setToken($this->secureRandom->generate(32));
 		$session->setLastContact($this->timeFactory->getTime());
 
 		$session = $this->sessionMapper->insert($session);
@@ -91,12 +91,34 @@ class SessionService {
 		return $this->sessionMapper->deleteInactive();
 	}
 
-	public function notifyAllSessions(IQueue $queue, int $boardId, $event, $excludeUserId, $body) {
+	public function notifyAllSessions(IQueue $queue, int $boardId, $event, $body, $causingSessionToken = null) {
 		$activeSessions = $this->sessionMapper->findAllActive($boardId);
-
+		$userIds = [];
 		foreach ($activeSessions as $session) {
+			if ($causingSessionToken && $session->getToken() === $causingSessionToken) {
+				// Limitation:
+				// If the same user has a second session active, the session $causingSessionToken
+				// still gets notified due to the current fact, that notify_push only supports
+				// to specify users, not individual sessions
+				// https://github.com/nextcloud/notify_push/issues/195
+				continue;
+			}
+
+			// don't notify the same user multiple times
+			if (!in_array($session->getUserId(), $userIds)) {
+				$userIds[] = $session->getUserId();
+			}
+		}
+
+		if ($causingSessionToken) {
+			// we only send a slice of the session token to everyone
+			// since knowledge of the full token allows everyone
+			// to close the session maliciously
+			$body['_causingSessionToken'] = substr($causingSessionToken, 0, 12);
+		}
+		foreach ($userIds as $userId) {
 			$queue->push('notify_custom', [
-				'user' => $session->getUserId(),
+				'user' => $userId,
 				'message' => $event,
 				'body' => $body
 			]);

src/sessions.js

@@ -21,13 +21,36 @@
 import { listen } from '@nextcloud/notify_push'
 import { sessionApi } from './services/SessionApi.js'
 import store from './store/main.js'
+import axios from '@nextcloud/axios'
 
 const SESSION_INTERVAL = 90 // in seconds
 
 let hasPush = false
 
+/**
+ * used to verify, whether an event is originated by ourselves
+ *
+ * @param token
+ */
+function isOurSessionToken(token) {
+	if (axios.defaults.headers['x-nc-deck-session']
+		&& axios.defaults.headers['x-nc-deck-session'].startsWith(token)) {
+		return true
+	} else {
+		return false
+	}
+}
+
 hasPush = listen('deck_board_update', (name, body) => {
-	triggerDeckReload(body.id)
+		// ignore update events which we have triggered ourselves
+	if (isOurSessionToken(body._causingSessionToken)) return
+
+	// only handle update events for the currently open board
+	const currentBoardId = store.state.currentBoard?.id
+	if (body.id !== currentBoardId) return
+
+	store.dispatch('refreshBoard', currentBoardId)
+})
 })
 
 /**
@@ -38,21 +61,6 @@ export function isNotifyPushEnabled() {
 	return hasPush
 }
 
-/**
- * Triggers a reload of the deck, if the provided id
- * matches the current open deck
- *
- * @param triggeredBoardId
- */
-export function triggerDeckReload(triggeredBoardId) {
-	const currentBoardId = store.state.currentBoard?.id
-
-	// only handle update events for the currently open board
-	if (triggeredBoardId !== currentBoardId) return
-
-	store.dispatch('refreshBoard', currentBoardId)
-}
-
 /**
  *
  * @param boardId
@@ -74,6 +82,7 @@ export function createSession(boardId) {
 		tokenPromise = sessionApi.createSession(boardId).then(res => res.token)
 		tokenPromise.then((t) => {
 			token = t
+			axios.defaults.headers['x-nc-deck-session'] = t
 		})
 	}
 	create()
@@ -95,12 +104,13 @@ export function createSession(boardId) {
 	// periodically notify the server that we are still here
 	let interval = setInterval(ensureSession, SESSION_INTERVAL * 1000)
 
-	// close session when
+	// close session when tab gets hidden/inactive
 	const visibilitychangeListener = () => {
 		if (document.visibilityState === 'hidden') {
 			sessionApi.closeSessionViaBeacon(boardId, token)
 			tokenPromise = null
 			token = null
+			delete axios.defaults.headers['x-nc-deck-session']
 
 			// stop session refresh interval
 			clearInterval(interval)
@@ -110,7 +120,7 @@ export function createSession(boardId) {
 
 			// we must assume that the websocket connection was
 			// paused and we have missed updates in the meantime.
-			triggerDeckReload()
+			store.dispatch('refreshBoard', store.state.currentBoard?.id)
 
 			// restart session refresh interval
 			interval = setInterval(ensureSession, SESSION_INTERVAL * 1000)