owncloud/core

<?php
/**
 * @author Piotr Mrowczynski piotr@owncloud.com
 *
 * @copyright Copyright (c) 2019, 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\Files_Sharing;

use OCP\Files\File;
use OCP\Files\Folder;
use OCP\Files\Node;
use OCP\Files\NotFoundException;

/**
 * Handles restricting for download of files
 */
class ViewOnly {
    /** @var Folder */
    private $userFolder;

    public function __construct(Folder $userFolder) {
        $this->userFolder = $userFolder;
    }

    /**
     * @param string[] $pathsToCheck
     * @return bool
     */
    public function check($pathsToCheck) {
        // If any of elements cannot be downloaded, prevent whole download
        foreach ($pathsToCheck as $file) {
            try {
                $info = $this->userFolder->get($file);
                if ($info instanceof File) {
                    // access to filecache is expensive in the loop
                    if (!$this->checkFileInfo($info)) {
                        return false;
                    }
                } elseif ($info instanceof Folder) {
                    // get directory content is rather cheap query
                    if (!$this->dirRecursiveCheck($info)) {
                        return false;
                    }
                }
            } catch (NotFoundException $e) {
                continue;
            }
        }
        return true;
    }

    /**
     * @param Folder $dirInfo
     * @return bool
     * @throws NotFoundException
     */
    private function dirRecursiveCheck(Folder $dirInfo) {
        if (!$this->checkFileInfo($dirInfo)) {
            return false;
        }
        // If any of elements cannot be downloaded, prevent whole download
        $files = $dirInfo->getDirectoryListing();
        foreach ($files as $file) {
            if ($file instanceof File) {
                if (!$this->checkFileInfo($file)) {
                    return false;
                }
            } elseif ($file instanceof Folder) {
                return $this->dirRecursiveCheck($file);
            }
        }

        return true;
    }

    /**
     * @param Node $fileInfo
     * @return bool
     * @throws NotFoundException
     */
    private function checkFileInfo(Node $fileInfo) {
        // Restrict view-only to nodes which are shared
        $storage = $fileInfo->getStorage();
        if (!$storage->instanceOfStorage(SharedStorage::class)) {
            return true;
        }

        // Extract extra permissions
        /** @var \OCA\Files_Sharing\SharedStorage $storage */
        '@phan-var \OCA\Files_Sharing\SharedStorage $storage';
        $share = $storage->getShare();

        // Check if read-only and on whether permission can download is both set and disabled.

        $canDownload = $share->getAttributes()->getAttribute('permissions', 'download');
        if ($canDownload !== null && !$canDownload) {
            return false;
        }
        return true;
    }
}