1 files changed, 104 insertions, 0 deletions
diff --git a/lib/private/Security/RateLimiting/Backend/MemoryCacheBackend.php b/lib/private/Security/RateLimiting/Backend/MemoryCacheBackend.php
new file mode 100644
index 00000000000..4c33b49d05e
--- /dev/null
+++ b/lib/private/Security/RateLimiting/Backend/MemoryCacheBackend.php
@@ -0,0 +1,104 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2017 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\Security\RateLimiting\Backend;
+
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\ICache;
+use OCP\ICacheFactory;
+use OCP\IConfig;
+
+/**
+ * Class MemoryCacheBackend uses the configured distributed memory cache for storing
+ * rate limiting data.
+ *
+ * @package OC\Security\RateLimiting\Backend
+ */
+class MemoryCacheBackend implements IBackend {
+	private ICache $cache;
+
+	public function __construct(
+		private IConfig $config,
+		ICacheFactory $cacheFactory,
+		private ITimeFactory $timeFactory,
+	) {
+		$this->cache = $cacheFactory->createDistributed(self::class);
+	}
+
+	private function hash(
+		string $methodIdentifier,
+		string $userIdentifier,
+	): string {
+		return hash('sha512', $methodIdentifier . $userIdentifier);
+	}
+
+	private function getExistingAttempts(string $identifier): array {
+		$cachedAttempts = $this->cache->get($identifier);
+		if ($cachedAttempts === null) {
+			return [];
+		}
+
+		$cachedAttempts = json_decode($cachedAttempts, true);
+		if (\is_array($cachedAttempts)) {
+			return $cachedAttempts;
+		}
+
+		return [];
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getAttempts(
+		string $methodIdentifier,
+		string $userIdentifier,
+	): int {
+		$identifier = $this->hash($methodIdentifier, $userIdentifier);
+		$existingAttempts = $this->getExistingAttempts($identifier);
+
+		$count = 0;
+		$currentTime = $this->timeFactory->getTime();
+		foreach ($existingAttempts as $expirationTime) {
+			if ($expirationTime > $currentTime) {
+				$count++;
+			}
+		}
+
+		return $count;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function registerAttempt(
+		string $methodIdentifier,
+		string $userIdentifier,
+		int $period,
+	): void {
+		$identifier = $this->hash($methodIdentifier, $userIdentifier);
+		$existingAttempts = $this->getExistingAttempts($identifier);
+		$currentTime = $this->timeFactory->getTime();
+
+		// Unset all attempts that are already expired
+		foreach ($existingAttempts as $key => $expirationTime) {
+			if ($expirationTime < $currentTime) {
+				unset($existingAttempts[$key]);
+			}
+		}
+		$existingAttempts = array_values($existingAttempts);
+
+		// Store the new attempt
+		$existingAttempts[] = (string)($currentTime + $period);
+
+		if (!$this->config->getSystemValueBool('ratelimit.protection.enabled', true)) {
+			return;
+		}
+
+		$this->cache->set($identifier, json_encode($existingAttempts));
+	}
+}