server/apps/files_sharing/lib/external/storage.php

<?php
/**
 * @author Lukas Reschke <lukas@owncloud.com>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Vincent Petry <pvince81@owncloud.com>
 *
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * 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, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OCA\Files_Sharing\External;

use GuzzleHttp\Exception\ClientException;
use GuzzleHttp\Exception\ConnectException;
use OC\Files\Storage\DAV;
use OC\ForbiddenException;
use OCA\FederatedFileSharing\DiscoveryManager;
use OCA\Files_Sharing\ISharedStorage;
use OCP\Files\NotFoundException;
use OCP\Files\StorageInvalidException;
use OCP\Files\StorageNotAvailableException;

class Storage extends DAV implements ISharedStorage {
	/** @var string */
	private $remoteUser;
	/** @var string */
	private $remote;
	/** @var string */
	private $mountPoint;
	/** @var string */
	private $token;
	/** @var \OCP\ICacheFactory */
	private $memcacheFactory;
	/** @var \OCP\Http\Client\IClientService */
	private $httpClient;
	/** @var \OCP\ICertificateManager */
	private $certificateManager;
	/** @var bool */
	private $updateChecked = false;

	/**
	 * @var \OCA\Files_Sharing\External\Manager
	 */
	private $manager;

	public function __construct($options) {
		$this->memcacheFactory = \OC::$server->getMemCacheFactory();
		$this->httpClient = \OC::$server->getHTTPClientService();
		$discoveryManager = new DiscoveryManager(
			$this->memcacheFactory,
			\OC::$server->getHTTPClientService()
		);

		$this->manager = $options['manager'];
		$this->certificateManager = $options['certificateManager'];
		$this->remote = $options['remote'];
		$this->remoteUser = $options['owner'];
		list($protocol, $remote) = explode('://', $this->remote);
		if (strpos($remote, '/')) {
			list($host, $root) = explode('/', $remote, 2);
		} else {
			$host = $remote;
			$root = '';
		}
		$secure = $protocol === 'https';
		$root = rtrim($root, '/') . $discoveryManager->getWebDavEndpoint($this->remote);
		$this->mountPoint = $options['mountpoint'];
		$this->token = $options['token'];
		parent::__construct(array(
			'secure' => $secure,
			'host' => $host,
			'root' => $root,
			'user' => $options['token'],
			'password' => (string)$options['password']
		));

		$this->getWatcher()->setPolicy(\OC\Files\Cache\Watcher::CHECK_ONCE);
	}

	public function getRemoteUser() {
		return $this->remoteUser;
	}

	public function getRemote() {
		return $this->remote;
	}

	public function getMountPoint() {
		return $this->mountPoint;
	}

	public function getToken() {
		return $this->token;
	}

	public function getPassword() {
		return $this->password;
	}

	/**
	 * @brief get id of the mount point
	 * @return string
	 */
	public function getId() {
		return 'shared::' . md5($this->token . '@' . $this->remote);
	}

	public function getCache($path = '', $storage = null) {
		if (is_null($this->cache)) {
			$this->cache = new Cache($this, $this->remote, $this->remoteUser);
		}
		return $this->cache;
	}

	/**
	 * @param string $path
	 * @param \OC\Files\Storage\Storage $storage
	 * @return \OCA\Files_Sharing\External\Scanner
	 */
	public function getScanner($path = '', $storage = null) {
		if (!$storage) {
			$storage = $this;
		}
		if(!$this->remoteIsOwnCloud()) {
			return parent::getScanner($path, $storage);
		}
		if (!isset($this->scanner)) {
			$this->scanner = new Scanner($storage);
		}
		return $this->scanner;
	}

	/**
	 * check if a file or folder has been updated since $time
	 *
	 * @param string $path
	 * @param int $time
	 * @throws \OCP\Files\StorageNotAvailableException
	 * @throws \OCP\Files\StorageInvalidException
	 * @return bool
	 */
	public function hasUpdated($path, $time) {
		// since for owncloud webdav servers we can rely on etag propagation we only need to check the root of the storage
		// because of that we only do one check for the entire storage per request
		if ($this->updateChecked) {
			return false;
		}
		$this->updateChecked = true;
		try {
			return parent::hasUpdated('', $time);
		} catch (StorageInvalidException $e) {
			// check if it needs to be removed
			$this->checkStorageAvailability();
			throw $e;
		} catch (StorageNotAvailableException $e) {
			// check if it needs to be removed or just temp unavailable
			$this->checkStorageAvailability();
			throw $e;
		}
	}

	/**
	 * Check whether this storage is permanently or temporarily
	 * unavailable
	 *
	 * @throws \OCP\Files\StorageNotAvailableException
	 * @throws \OCP\Files\StorageInvalidException
	 */
	public function checkStorageAvailability() {
		// see if we can find out why the share is unavailable
		try {
			$this->getShareInfo();
		} catch (NotFoundException $e) {
			// a 404 can either mean that the share no longer exists or there is no ownCloud on the remote
			if ($this->testRemote()) {
				// valid ownCloud instance means that the public share no longer exists
				// since this is permanent (re-sharing the file will create a new token)
				// we remove the invalid storage
				$this->manager->removeShare($this->mountPoint);
				$this->manager->getMountManager()->removeMount($this->mountPoint);
				throw new StorageInvalidException();
			} else {
				// ownCloud instance is gone, likely to be a temporary server configuration error
				throw new StorageNotAvailableException();
			}
		} catch (ForbiddenException $e) {
			// auth error, remove share for now (provide a dialog in the future)
			$this->manager->removeShare($this->mountPoint);
			$this->manager->getMountManager()->removeMount($this->mountPoint);
			throw new StorageInvalidException();
		} catch (\GuzzleHttp\Exception\ConnectException $e) {
			throw new StorageNotAvailableException();
		} catch (\GuzzleHttp\Exception\RequestException $e) {
			throw new StorageNotAvailableException();
		} catch (\Exception $e) {
			throw $e;
		}
	}

	public function file_exists($path) {
		if ($path === '') {
			return true;
		} else {
			return parent::file_exists($path);
		}
	}

	/**
	 * check if the configured remote is a valid federated share provider
	 *
	 * @return bool
	 */
	protected function testRemote() {
		try {
			return $this->testRemoteUrl($this->remote . '/ocs-provider/index.php')
				|| $this->testRemoteUrl($this->remote . '/ocs-provider/')
				|| $this->testRemoteUrl($this->remote . '/status.php');
		} catch (\Exception $e) {
			return false;
		}
	}

	/**
	 * @param string $url
	 * @return bool
	 */
	private function testRemoteUrl($url) {
		$cache = $this->memcacheFactory->create('files_sharing_remote_url');
		if($cache->hasKey($url)) {
			return (bool)$cache->get($url);
		}

		$client = $this->httpClient->newClient();
		try {
			$result = $client->get($url)->getBody();
			$data = json_decode($result);
			$returnValue = (is_object($data) && !empty($data->version));
		} catch (ConnectException $e) {
			$returnValue = false;
		} catch (ClientException $e) {
			$returnValue = false;
		}

		$cache->set($url, $returnValue);
		return $returnValue;
	}

	/**
	 * Whether the remote is an ownCloud, used since some sharing features are not
	 * standardized. Let's use this to detect whether to use it.
	 *
	 * @return bool
	 */
	private function remoteIsOwnCloud() {
		if(defined('PHPUNIT_RUN') || !$this->testRemoteUrl($this->getRemote() . '/status.php')) {
			return false;
		}
		return true;
	}

	/**
	 * @return mixed
	 * @throws ForbiddenException
	 * @throws NotFoundException
	 * @throws \Exception
	 */
	public function getShareInfo() {
		$remote = $this->getRemote();
		$token = $this->getToken();
		$password = $this->getPassword();

		// If remote is not an ownCloud do not try to get any share info
		if(!$this->remoteIsOwnCloud()) {
			return ['status' => 'unsupported'];
		}

		$url = rtrim($remote, '/') . '/index.php/apps/files_sharing/shareinfo?t=' . $token;

		// TODO: DI
		$client = \OC::$server->getHTTPClientService()->newClient();
		try {
			$response = $client->post($url, ['body' => ['password' => $password]]);
		} catch (\GuzzleHttp\Exception\RequestException $e) {
			if ($e->getCode() === 401 || $e->getCode() === 403) {
				throw new ForbiddenException();
			}
			if ($e->getCode() === 404) {
				throw new NotFoundException();
			}
			// throw this to be on the safe side: the share will still be visible
			// in the UI in case the failure is intermittent, and the user will
			// be able to decide whether to remove it if it's really gone
			throw new StorageNotAvailableException();
		}

		return json_decode($response->getBody(), true);
	}

	public function getOwner($path) {
		list(, $remote) = explode('://', $this->remote, 2);
		return $this->remoteUser . '@' . $remote;
	}

	public function isSharable($path) {
		if (\OCP\Util::isSharingDisabledForUser() || !\OC\Share\Share::isResharingAllowed()) {
			return false;
		}
		return ($this->getPermissions($path) & \OCP\Constants::PERMISSION_SHARE);
	}

}