1 files changed, 87 insertions, 0 deletions
diff --git a/apps/dav/lib/CalDAV/Security/RateLimitingPlugin.php b/apps/dav/lib/CalDAV/Security/RateLimitingPlugin.php
new file mode 100644
index 00000000000..311157994e2
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Security/RateLimitingPlugin.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2023 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\DAV\CalDAV\Security;
+
+use OC\Security\RateLimiting\Exception\RateLimitExceededException;
+use OC\Security\RateLimiting\Limiter;
+use OCA\DAV\CalDAV\CalDavBackend;
+use OCA\DAV\Connector\Sabre\Exception\TooManyRequests;
+use OCP\IAppConfig;
+use OCP\IUserManager;
+use Psr\Log\LoggerInterface;
+use Sabre\DAV;
+use Sabre\DAV\Exception\Forbidden;
+use Sabre\DAV\ServerPlugin;
+use function count;
+use function explode;
+
+class RateLimitingPlugin extends ServerPlugin {
+
+	private Limiter $limiter;
+
+	public function __construct(
+		Limiter $limiter,
+		private IUserManager $userManager,
+		private CalDavBackend $calDavBackend,
+		private LoggerInterface $logger,
+		private IAppConfig $config,
+		private ?string $userId,
+	) {
+		$this->limiter = $limiter;
+	}
+
+	public function initialize(DAV\Server $server): void {
+		$server->on('beforeBind', [$this, 'beforeBind'], 1);
+	}
+
+	public function beforeBind(string $path): void {
+		if ($this->userId === null) {
+			// We only care about authenticated users here
+			return;
+		}
+		$user = $this->userManager->get($this->userId);
+		if ($user === null) {
+			// We only care about authenticated users here
+			return;
+		}
+
+		$pathParts = explode('/', $path);
+		if (count($pathParts) === 3 && $pathParts[0] === 'calendars') {
+			// Path looks like calendars/username/calendarname so a new calendar or subscription is created
+			try {
+				$this->limiter->registerUserRequest(
+					'caldav-create-calendar',
+					$this->config->getValueInt('dav', 'rateLimitCalendarCreation', 10),
+					$this->config->getValueInt('dav', 'rateLimitPeriodCalendarCreation', 3600),
+					$user
+				);
+			} catch (RateLimitExceededException $e) {
+				throw new TooManyRequests('Too many calendars created', 0, $e);
+			}
+
+			$calendarLimit = $this->config->getValueInt('dav', 'maximumCalendarsSubscriptions', 30);
+			if ($calendarLimit === -1) {
+				return;
+			}
+			$numCalendars = $this->calDavBackend->getCalendarsForUserCount('principals/users/' . $user->getUID());
+			$numSubscriptions = $this->calDavBackend->getSubscriptionsForUserCount('principals/users/' . $user->getUID());
+
+			if (($numCalendars + $numSubscriptions) >= $calendarLimit) {
+				$this->logger->warning('Maximum number of calendars/subscriptions reached', [
+					'calendars' => $numCalendars,
+					'subscription' => $numSubscriptions,
+					'limit' => $calendarLimit,
+				]);
+				throw new Forbidden('Calendar limit reached', 0);
+			}
+		}
+	}
+
+}