provide public discovery service to discover OCS end-points on another server

Signed-off-by: Bjoern Schiessle <bjoern@schiessle.org>

lib/private/AppFramework/DependencyInjection/DIContainer.php

@@ -56,6 +56,8 @@ use OCP\IL10N;
 use OCP\IRequest;
 use OCP\IServerContainer;
 use OCP\IUserSession;
+use OCP\Files\Mount\IMountManager;
+use OCP\OCS\IDiscoveryService;
 use OCP\RichObjectStrings\IValidator;
 use OCP\Util;
 
@@ -137,6 +139,13 @@ class DIContainer extends SimpleContainer implements IAppContainer {
 			return $c;
 		});
 
+		$this->registerService(IMountManager::class, function () {
+			return $this->getServer()->getMountManager();
+		});
+		$this->registerService(IDiscoveryService::class, function($c) {
+			return $this->getServer()->getOCSDiscoveryService();
+		});
+
 		// commonly used attributes
 		$this->registerService('UserId', function ($c) {
 			return $c->query('OCP\\IUserSession')->getSession()->get('user_id');

lib/private/OCS/DiscoveryService.php

@@ -0,0 +1,125 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Bjoern Schiessle <bjoern@schiessle.org>
+ *
+ * @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\OCS;
+
+use OCP\AppFramework\Http;
+use OCP\Http\Client\IClient;
+use OCP\Http\Client\IClientService;
+use OCP\ICache;
+use OCP\ICacheFactory;
+use OCP\OCS\IDiscoveryService;
+
+class DiscoveryService implements IDiscoveryService {
+
+	/** @var ICache */
+	private $cache;
+
+	/** @var IClient */
+	private $client;
+
+	/**
+	 * @param ICacheFactory $cacheFactory
+	 * @param IClientService $clientService
+	 */
+	public function __construct(ICacheFactory $cacheFactory,
+								IClientService $clientService
+	) {
+		$this->cache = $cacheFactory->create('ocs-discovery');
+		$this->client = $clientService->newClient();
+	}
+
+
+	/**
+	 * Discover OCS end-points
+	 *
+	 * If no valid discovery data is found the defaults are returned
+	 *
+	 * @param string $remote
+	 * @param string $service the service you want to discover
+	 * @return array
+	 */
+	public function discover($remote, $service) {
+		// Check the cache first
+		$cacheData = $this->cache->get($remote . '#' . $service);
+		if($cacheData) {
+			return json_decode($cacheData, true);
+		}
+
+		$discoveredServices = [];
+
+		// query the remote server for available services
+		try {
+			$response = $this->client->get($remote . '/ocs-provider/', [
+				'timeout' => 10,
+				'connect_timeout' => 10,
+			]);
+			if($response->getStatusCode() === Http::STATUS_OK) {
+				$decodedServices = json_decode($response->getBody(), true);
+				$discoveredServices = $this->getEndpoints($decodedServices, $service);
+			}
+		} catch (\Exception $e) {
+			// if we couldn't discover the service or any end-points we return a empty array
+			return [];
+		}
+
+		// Write into cache
+		$this->cache->set($remote . '#' . $service, json_encode($discoveredServices));
+		return $discoveredServices;
+	}
+
+	/**
+	 * get requested end-points from the requested service
+	 *
+	 * @param $decodedServices
+	 * @param $service
+	 * @return array
+	 */
+	private function getEndpoints($decodedServices, $service) {
+
+		$discoveredServices = [];
+
+		if(is_array($decodedServices) &&
+			isset($decodedServices['services'][$service]['endpoints'])
+		) {
+			foreach ($decodedServices['services'][$service]['endpoints'] as $endpoint => $url) {
+				if($this->isSafeUrl($url)) {
+					$discoveredServices[$endpoint] = $url;
+				}
+			}
+		}
+
+		return $discoveredServices;
+	}
+
+	/**
+	 * Returns whether the specified URL includes only safe characters, if not
+	 * returns false
+	 *
+	 * @param string $url
+	 * @return bool
+	 */
+	private function isSafeUrl($url) {
+		return (bool)preg_match('/^[\/\.A-Za-z0-9]+$/', $url);
+	}
+
+}

lib/private/Server.php

@@ -77,6 +77,7 @@ use OC\Mail\Mailer;
 use OC\Memcache\ArrayCache;
 use OC\Memcache\Factory;
 use OC\Notification\Manager;
+use OC\OCS\DiscoveryService;
 use OC\Repair\NC11\CleanPreviewsBackgroundJob;
 use OC\RichObjectStrings\Validator;
 use OC\Security\Bruteforce\Throttler;
@@ -936,6 +937,10 @@ class Server extends ServerContainer implements IServerContainer {
 			});
 		});
 
+		$this->registerService('OCSDiscoveryService', function (Server $c) {
+			return new DiscoveryService($c->getMemCacheFactory(), $c->getHTTPClientService());
+		});
+
 		$this->registerService(ICloudIdManager::class, function (Server $c) {
 			return new CloudIdManager();
 		});
@@ -996,6 +1001,14 @@ class Server extends ServerContainer implements IServerContainer {
 		return $this->query('EncryptionKeyStorage');
 	}
 
+	/**
+	 * @return \OC\OCS\DiscoveryService
+	 */
+	public function getOCSDiscoveryService() {
+		return $this->query('OCSDiscoveryService');
+	}
+
+
 	/**
 	 * The current request object holding all information about the request
 	 * currently being processed is returned from this method.

lib/public/OCS/IDiscoveryService.php

@@ -0,0 +1,48 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Bjoern Schiessle <bjoern@schiessle.org>
+ *
+ * @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 OCP\OCS;
+
+/**
+ * Interface IDiscoveryService
+ *
+ * Allows you to discover OCS end-points on a remote server
+ *
+ * @package OCP\OCS
+ * @since 12.0.0
+ */
+interface IDiscoveryService {
+
+	/**
+	 * Discover OCS end-points
+	 *
+	 * If no valid discovery data is found the defaults are returned
+	 *
+	 * @since 12.0.0
+	 *
+	 * @param string $remote
+	 * @param string $service the service you want to discover
+	 * @return array
+	 */
+	public function discover($remote, $service);
+
+}