Add support for ratelimiting via annotations

This allows adding rate limiting via annotations to controllers, as one example:

```
@UserRateThrottle(limit=5, period=100)
@AnonRateThrottle(limit=1, period=100)
```

Would mean that logged-in users can access the page 5 times within 100 seconds, and anonymous users 1 time within 100 seconds. If only an AnonRateThrottle is specified that one will also be applied to logged-in users.

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

4 files changed, 287 insertions, 0 deletions

diff --git a/lib/private/Security/RateLimiting/Backend/IBackend.php b/lib/private/Security/RateLimiting/Backend/IBackend.php
new file mode 100644
index 00000000000..092c0e7bb8a
--- /dev/null
+++ b/lib/private/Security/RateLimiting/Backend/IBackend.php
@@ -0,0 +1,50 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Security\RateLimiting\Backend;
+
+/**
+ * Interface IBackend defines a storage backend for the rate limiting data. It
+ * should be noted that writing and reading rate limiting data is an expensive
+ * operation and one should thus make sure to only use sufficient fast backends.
+ *
+ * @package OC\Security\RateLimiting\Backend
+ */
+interface IBackend {
+	/**
+	 * Gets the amount of attempts within the last specified seconds
+	 *
+	 * @param string $methodIdentifier
+	 * @param string $userIdentifier
+	 * @param int $seconds
+	 * @return int
+	 */
+	public function getAttempts($methodIdentifier, $userIdentifier, $seconds);
+
+	/**
+	 * Registers an attempt
+	 *
+	 * @param string $methodIdentifier
+	 * @param string $userIdentifier
+	 * @param int $timestamp
+	 */
+	public function registerAttempt($methodIdentifier, $userIdentifier, $timestamp);
+}
diff --git a/lib/private/Security/RateLimiting/Backend/MemoryCache.php b/lib/private/Security/RateLimiting/Backend/MemoryCache.php
new file mode 100644
index 00000000000..a0c53335bcf
--- /dev/null
+++ b/lib/private/Security/RateLimiting/Backend/MemoryCache.php
@@ -0,0 +1,100 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Security\RateLimiting\Backend;
+
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\ICache;
+use OCP\ICacheFactory;
+
+/**
+ * Class MemoryCache uses the configured distributed memory cache for storing
+ * rate limiting data.
+ *
+ * @package OC\Security\RateLimiting\Backend
+ */
+class MemoryCache implements IBackend {
+	/** @var ICache */
+	private $cache;
+	/** @var ITimeFactory */
+	private $timeFactory;
+
+	/**
+	 * @param ICacheFactory $cacheFactory
+	 * @param ITimeFactory $timeFactory
+	 */
+	public function __construct(ICacheFactory $cacheFactory,
+								ITimeFactory $timeFactory) {
+		$this->cache = $cacheFactory->create(__CLASS__);
+		$this->timeFactory = $timeFactory;
+	}
+
+	/**
+	 * @param string $methodIdentifier
+	 * @param string $userIdentifier
+	 * @return string
+	 */
+	private function hash($methodIdentifier, $userIdentifier) {
+		return hash('sha512', $methodIdentifier . $userIdentifier);
+	}
+
+	/**
+	 * @param string $identifier
+	 * @return array
+	 */
+	private function getExistingAttempts($identifier) {
+		$cachedAttempts = json_decode($this->cache->get($identifier), true);
+		if(is_array($cachedAttempts)) {
+			return $cachedAttempts;
+		}
+
+		return [];
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getAttempts($methodIdentifier, $userIdentifier, $seconds) {
+		$identifier = $this->hash($methodIdentifier, $userIdentifier);
+		$existingAttempts = $this->getExistingAttempts($identifier);
+
+		$count = 0;
+		$currentTime = $this->timeFactory->getTime();
+		/** @var array $existingAttempts */
+		foreach ($existingAttempts as $attempt) {
+			if(($attempt + $seconds) > $currentTime) {
+				$count++;
+			}
+		}
+
+		return $count;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function registerAttempt($methodIdentifier, $userIdentifier, $timestamp) {
+		$identifier = $this->hash($methodIdentifier, $userIdentifier);
+		$existingAttempts = $this->getExistingAttempts($identifier);
+		$existingAttempts[] = (string)$timestamp;
+		$this->cache->set($identifier, json_encode($existingAttempts));
+	}
+}
diff --git a/lib/private/Security/RateLimiting/Exception/RateLimitExceededException.php b/lib/private/Security/RateLimiting/Exception/RateLimitExceededException.php
new file mode 100644
index 00000000000..34cbec31c73
--- /dev/null
+++ b/lib/private/Security/RateLimiting/Exception/RateLimitExceededException.php
@@ -0,0 +1,31 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Security\RateLimiting\Exception;
+
+use OC\AppFramework\Middleware\Security\Exceptions\SecurityException;
+use OCP\AppFramework\Http;
+
+class RateLimitExceededException extends SecurityException {
+	public function __construct() {
+		parent::__construct('Rate limit exceeded', Http::STATUS_TOO_MANY_REQUESTS);
+	}
+}
diff --git a/lib/private/Security/RateLimiting/Limiter.php b/lib/private/Security/RateLimiting/Limiter.php
new file mode 100644
index 00000000000..5c084eb934b
--- /dev/null
+++ b/lib/private/Security/RateLimiting/Limiter.php
@@ -0,0 +1,106 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Security\RateLimiting;
+
+use OC\Security\Normalizer\IpAddress;
+use OC\Security\RateLimiting\Backend\IBackend;
+use OC\Security\RateLimiting\Exception\RateLimitExceededException;
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IRequest;
+use OCP\IUser;
+use OCP\IUserSession;
+
+class Limiter {
+	/** @var IBackend */
+	private $backend;
+	/** @var ITimeFactory */
+	private $timeFactory;
+
+	/**
+	 * @param IUserSession $userSession
+	 * @param IRequest $request
+	 * @param ITimeFactory $timeFactory
+	 * @param IBackend $backend
+	 */
+	public function __construct(IUserSession $userSession,
+								IRequest $request,
+								ITimeFactory $timeFactory,
+								IBackend $backend) {
+		$this->backend = $backend;
+		$this->timeFactory = $timeFactory;
+	}
+
+	/**
+	 * @param string $methodIdentifier
+	 * @param string $userIdentifier
+	 * @param int $period
+	 * @param int $limit
+	 * @throws RateLimitExceededException
+	 */
+	private function register($methodIdentifier,
+							  $userIdentifier,
+							  $period,
+							  $limit) {
+		$existingAttempts = $this->backend->getAttempts($methodIdentifier, $userIdentifier, (int)$period);
+		if ($existingAttempts >= (int)$limit) {
+			throw new RateLimitExceededException();
+		}
+
+		$this->backend->registerAttempt($methodIdentifier, $userIdentifier, $this->timeFactory->getTime());
+	}
+
+	/**
+	 * Registers attempt for an anonymous request
+	 *
+	 * @param string $identifier
+	 * @param int $anonLimit
+	 * @param int $anonPeriod
+	 * @param string $ip
+	 * @throws RateLimitExceededException
+	 */
+	public function registerAnonRequest($identifier,
+										$anonLimit,
+										$anonPeriod,
+										$ip) {
+		$ipSubnet = (new IpAddress($ip))->getSubnet();
+
+		$anonHashIdentifier = hash('sha512', 'anon::' . $identifier . $ipSubnet);
+		$this->register($identifier, $anonHashIdentifier, $anonPeriod, $anonLimit);
+	}
+
+	/**
+	 * Registers attempt for an authenticated request
+	 *
+	 * @param string $identifier
+	 * @param int $userLimit
+	 * @param int $userPeriod
+	 * @param IUser $user
+	 * @throws RateLimitExceededException
+	 */
+	public function registerUserRequest($identifier,
+										$userLimit,
+										$userPeriod,
+										IUser $user) {
+		$userHashIdentifier = hash('sha512', 'user::' . $identifier . $user->getUID());
+		$this->register($identifier, $userHashIdentifier, $userPeriod, $userLimit);
+	}
+}