owncloud/core

<?php
/**
 * @author Juan Pablo Villafáñez <jvillafanez@solidgear.es>
 *
 * @copyright Copyright (c) 2018, 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\IConfig;
use OCP\IGroup;

/**
 * Class to handle a blacklist for sharing. The main functionality is to check if a particular group
 * has been blacklisted for sharing, which means that no one should be able to share with that group.
 *
 * Note that this class will only handle the configuration and perform the checks against the configuration.
 * This class won't prevent the sharing action by itself.
 */
class SharingBlacklist {
    /** @var IConfig */
    private $config;

    private $blacklistCache = null;

    public function __construct(IConfig $config) {
        $this->config = $config;
    }

    /**
     * Check if the target group is blacklisted
     * @param IGroup $group the group to check
     * @return bool true if the group is blacklisted, false otherwise
     */
    public function isGroupBlacklisted(IGroup $group) {
        $this->initCache();
        return (isset($this->blacklistCache['receivers']['ids'][$group->getGID()]));
    }

    /**
     * Clear the internal cache of this class. Use this function if any of the keys used by this class are changed
     * outside of this class, such as a direct change of the 'blacklisted_group_displaynames' in the appconfig table
     * Note that this is an object-based cache. It won't persist for multiple HTTP requests
     */
    public function clearCache() {
        $this->blacklistCache = null;
    }

    /**
     * Set the list of groups to be blacklisted by id.
     * @param string[] $ids a list with the ids of the groups to be blacklisted
     */
    public function setBlacklistedReceiverGroups(array $ids) {
        $this->config->setAppValue('files_sharing', 'blacklisted_receiver_groups', \json_encode($ids));
        $this->blacklistCache = null;  // clear the cache
    }

    /**
     * Get the list of blacklisted group ids
     * Note that this might contain wrong information
     * @return string[] the list of group ids
     */
    public function getBlacklistedReceiverGroups() {
        return \array_keys($this->fetchBlacklistedReceiverGroupIds());
    }

    private function initCache() {
        if ($this->blacklistCache === null) {
            $this->blacklistCache = [
                'receivers' => [
                    'ids' => $this->fetchBlacklistedReceiverGroupIds(),
                ],
            ];
        }
    }

    /**
     * @return bool[] an array with group ids as the keys, the values do not matter
     *                If the blacklisted receiver groups cannot be parsed as valid JSON,
     *                then an empty list is returned.
     *                Any parsed group ids that are not string, int or float are dropped from the list.
     */
    private function fetchBlacklistedReceiverGroupIds() {
        $configuredBlacklist = $this->config->getAppValue('files_sharing', 'blacklisted_receiver_groups', '[]');
        $decodedGroups = \json_decode($configuredBlacklist, true);

        if (!\is_array($decodedGroups)) {
            $decodedGroups = [];
        }

        $groupSet = [];
        foreach ($decodedGroups as $group) {
            if (\is_string($group) || \is_int($group) || \is_float($group)) {
                $groupSet[(string) $group] = true;
            }
        }

        return $groupSet;
    }
}