owncloud/core

<?php
/**
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 *
 * @copyright Copyright (c) 2017, ownCloud GmbH
 * @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\DAV\Files;

use OCA\DAV\Connector\Sabre\Exception\FileLocked;
use OCP\AppFramework\Utility\ITimeFactory;
use OCP\Encryption\Exceptions\GenericEncryptionException;
use OCP\Files\ForbiddenException;
use OCP\Files\IPreviewNode;
use OCP\Files\StorageNotAvailableException;
use OCP\IPreview;
use OCP\Lock\LockedException;
use Sabre\DAV\Exception;
use Sabre\DAV\Exception\BadRequest;
use Sabre\DAV\Exception\Forbidden;
use Sabre\DAV\Exception\NotFound;
use Sabre\DAV\Exception\ServiceUnavailable;
use Sabre\DAV\Server;
use Sabre\DAV\ServerPlugin;
use Sabre\HTTP\RequestInterface;
use Sabre\HTTP\ResponseInterface;

class PreviewPlugin extends ServerPlugin {
    /** @var Server */
    protected $server;
    /** @var ITimeFactory */
    private $timeFactory;
    /** @var IPreview */
    private $previewManager;

    /**
     * PreviewPlugin constructor.
     *
     * @param ITimeFactory $timeFactory
     * @param IPreview $previewManager
     */
    public function __construct(ITimeFactory $timeFactory, IPreview $previewManager) {
        $this->timeFactory = $timeFactory;
        $this->previewManager = $previewManager;
    }

    /**
     * Initializes the plugin and registers event handlers
     *
     * @param Server $server
     * @return void
     */
    public function initialize(Server $server) {
        $this->server = $server;
        $this->server->on('method:GET', [$this, 'httpGet'], 90);
    }

    /**
     * Intercepts GET requests on node urls ending with ?preview.
     * The node has to implement IPreviewNode
     *
     * @param RequestInterface $request
     * @param ResponseInterface $response
     * @return bool
     * @throws NotFound
     * @throws \Sabre\DAVACL\Exception\NeedPrivileges
     * @throws \Sabre\DAV\Exception\NotAuthenticated
     * @throws Forbidden
     * @throws FileLocked
     * @throws ServiceUnavailable
     */
    public function httpGet(RequestInterface $request, ResponseInterface $response) {
        $queryParams = $request->getQueryParameters();
        if (!\array_key_exists('preview', $queryParams)) {
            return true;
        }

        $path = $request->getPath();
        $node = $this->server->tree->getNodeForPath($path);

        if (!$node instanceof IFileNode) {
            throw new BadRequest('Unsupported file type');
        }
        $fileNode = $node->getNode();
        if (!$fileNode instanceof IPreviewNode) {
            throw new BadRequest('Unsupported file type');
        }

        // Checking ACL, if available.
        if ($aclPlugin = $this->server->getPlugin('acl')) {
            /** @var \Sabre\DAVACL\Plugin $aclPlugin */
            '@phan-var \Sabre\DAVACL\Plugin $aclPlugin';
            $aclPlugin->checkPrivileges($path, '{DAV:}read');
        }

        try {
            if (!$this->previewManager->isAvailable($fileNode)) {
                // no preview available or preview disabled
                throw new NotFound();
            }
            if ($image = $fileNode->getThumbnail($queryParams)) {
                if ($image === null || !$image->valid()) {
                    throw new NotFound();
                }
                $type = $image->mimeType();
                if (!\in_array($type, ['image/png', 'image/jpeg', 'image/gif'])) {
                    $type = 'application/octet-stream';
                }

                // Enable output buffering
                \ob_start();
                // Capture the output
                $image->show();
                $imageData = \ob_get_contents();
                // Clear the output buffer
                \ob_end_clean();

                $response->setHeader('Content-Type', $type);
                $response->setHeader('Content-Disposition', 'attachment');
                // cache 24h
                $response->setHeader('Cache-Control', 'max-age=86400, must-revalidate');
                $response->setHeader('Expires', \gmdate('D, d M Y H:i:s', $this->timeFactory->getTime() + 86400) . ' GMT');

                $response->setStatus(200);
                $response->setBody($imageData);

                // Returning false to break the event chain
                return false;
            }
        } catch (GenericEncryptionException $ex) {
            // returning 403 because some apps stops syncing if 503 is returned.
            throw new Forbidden('Encryption not ready: ' . $ex->getMessage());
        } catch (StorageNotAvailableException $ex) {
            throw new ServiceUnavailable('Failed to open file: ' . $ex->getMessage());
        } catch (ForbiddenException $ex) {
            throw new Forbidden($ex->getMessage(), $ex->getRetry());
        } catch (LockedException $ex) {
            throw new FileLocked($ex->getMessage(), $ex->getCode(), $ex);
        } catch (Exception $ex) {
            throw $ex;
        } catch (\Exception $ex) {
            throw new BadRequest($ex->getMessage(), $ex->getCode(), $ex);
        }

        // TODO: add forceIcon handling .... if still needed
        throw new NotFound();
    }
}