1 files changed, 144 insertions, 0 deletions
diff --git a/lib/private/Security/Bruteforce/Backend/MemoryCacheBackend.php b/lib/private/Security/Bruteforce/Backend/MemoryCacheBackend.php
new file mode 100644
index 00000000000..9a0723db47e
--- /dev/null
+++ b/lib/private/Security/Bruteforce/Backend/MemoryCacheBackend.php
@@ -0,0 +1,144 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2023 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\Security\Bruteforce\Backend;
+
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\ICache;
+use OCP\ICacheFactory;
+
+class MemoryCacheBackend implements IBackend {
+	private ICache $cache;
+
+	public function __construct(
+		ICacheFactory $cacheFactory,
+		private ITimeFactory $timeFactory,
+	) {
+		$this->cache = $cacheFactory->createDistributed(self::class);
+	}
+
+	private function hash(
+		null|string|array $data,
+	): ?string {
+		if ($data === null) {
+			return null;
+		}
+		if (!is_string($data)) {
+			$data = json_encode($data);
+		}
+		return hash('sha1', $data);
+	}
+
+	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 $ipSubnet,
+		int $maxAgeTimestamp,
+		?string $action = null,
+		?array $metadata = null,
+	): int {
+		$identifier = $this->hash($ipSubnet);
+		$actionHash = $this->hash($action);
+		$metadataHash = $this->hash($metadata);
+		$existingAttempts = $this->getExistingAttempts($identifier);
+
+		$count = 0;
+		foreach ($existingAttempts as $info) {
+			[$occurredTime, $attemptAction, $attemptMetadata] = explode('#', $info, 3);
+			if ($action === null || $attemptAction === $actionHash) {
+				if ($metadata === null || $attemptMetadata === $metadataHash) {
+					if ($occurredTime > $maxAgeTimestamp) {
+						$count++;
+					}
+				}
+			}
+		}
+
+		return $count;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function resetAttempts(
+		string $ipSubnet,
+		?string $action = null,
+		?array $metadata = null,
+	): void {
+		$identifier = $this->hash($ipSubnet);
+		if ($action === null) {
+			$this->cache->remove($identifier);
+		} else {
+			$actionHash = $this->hash($action);
+			$metadataHash = $this->hash($metadata);
+			$existingAttempts = $this->getExistingAttempts($identifier);
+			$maxAgeTimestamp = $this->timeFactory->getTime() - 12 * 3600;
+
+			foreach ($existingAttempts as $key => $info) {
+				[$occurredTime, $attemptAction, $attemptMetadata] = explode('#', $info, 3);
+				if ($attemptAction === $actionHash) {
+					if ($metadata === null || $attemptMetadata === $metadataHash) {
+						unset($existingAttempts[$key]);
+					} elseif ($occurredTime < $maxAgeTimestamp) {
+						unset($existingAttempts[$key]);
+					}
+				}
+			}
+
+			if (!empty($existingAttempts)) {
+				$this->cache->set($identifier, json_encode($existingAttempts), 12 * 3600);
+			} else {
+				$this->cache->remove($identifier);
+			}
+		}
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function registerAttempt(
+		string $ip,
+		string $ipSubnet,
+		int $timestamp,
+		string $action,
+		array $metadata = [],
+	): void {
+		$identifier = $this->hash($ipSubnet);
+		$existingAttempts = $this->getExistingAttempts($identifier);
+		$maxAgeTimestamp = $this->timeFactory->getTime() - 12 * 3600;
+
+		// Unset all attempts that are already expired
+		foreach ($existingAttempts as $key => $info) {
+			[$occurredTime,] = explode('#', $info, 3);
+			if ($occurredTime < $maxAgeTimestamp) {
+				unset($existingAttempts[$key]);
+			}
+		}
+		$existingAttempts = array_values($existingAttempts);
+
+		// Store the new attempt
+		$existingAttempts[] = $timestamp . '#' . $this->hash($action) . '#' . $this->hash($metadata);
+
+		$this->cache->set($identifier, json_encode($existingAttempts), 12 * 3600);
+	}
+}