friendica_2020-09-1_sharedHosting/src/Util/Security.php

<?php
/**
 * @file /src/Util/Security.php
 */

namespace Friendica\Util;

use Friendica\BaseObject;
use Friendica\Database\DBA;
use Friendica\Model\Contact;
use Friendica\Model\Group;
use Friendica\Model\User;

/**
 * Secures that User is allow to do requests
 */
class Security extends BaseObject
{
	public static function canWriteToUserWall($owner)
	{
		static $verified = 0;

		if (!local_user() && !remote_user()) {
			return false;
		}

		$uid = local_user();
		if ($uid == $owner) {
			return true;
		}

		if (local_user() && ($owner == 0)) {
			return true;
		}

		if (remote_user()) {
			// use remembered decision and avoid a DB lookup for each and every display item
			// DO NOT use this function if there are going to be multiple owners
			// We have a contact-id for an authenticated remote user, this block determines if the contact
			// belongs to this page owner, and has the necessary permissions to post content

			if ($verified === 2) {
				return true;
			} elseif ($verified === 1) {
				return false;
			} else {
				$cid = 0;

				if (!empty($_SESSION['remote'])) {
					foreach ($_SESSION['remote'] as $visitor) {
						if ($visitor['uid'] == $owner) {
							$cid = $visitor['cid'];
							break;
						}
					}
				}

				if (!$cid) {
					return false;
				}

				$r = q("SELECT `contact`.*, `user`.`page-flags` FROM `contact` INNER JOIN `user` on `user`.`uid` = `contact`.`uid`
					WHERE `contact`.`uid` = %d AND `contact`.`id` = %d AND `contact`.`blocked` = 0 AND `contact`.`pending` = 0
					AND `user`.`blockwall` = 0 AND `readonly` = 0  AND ( `contact`.`rel` IN ( %d , %d ) OR `user`.`page-flags` = %d ) LIMIT 1",
					intval($owner),
					intval($cid),
					intval(Contact::SHARING),
					intval(Contact::FRIEND),
					intval(User::PAGE_FLAGS_COMMUNITY)
				);

				if (DBA::isResult($r)) {
					$verified = 2;
					return true;
				} else {
					$verified = 1;
				}
			}
		}

		return false;
	}

	/// @TODO $groups should be array
	public static function getPermissionsSQLByUserId($owner_id, $remote_verified = false, $groups = null)
	{
		$local_user = local_user();
		$remote_user = remote_user();

		/*
		 * Construct permissions
		 *
		 * default permissions - anonymous user
		 */
		$sql = " AND allow_cid = ''
				 AND allow_gid = ''
				 AND deny_cid  = ''
				 AND deny_gid  = ''
		";

		/*
		 * Profile owner - everything is visible
		 */
		if ($local_user && $local_user == $owner_id) {
			$sql = '';
		/*
		 * Authenticated visitor. Unless pre-verified,
		 * check that the contact belongs to this $owner_id
		 * and load the groups the visitor belongs to.
		 * If pre-verified, the caller is expected to have already
		 * done this and passed the groups into this function.
		 */
		} elseif ($remote_user) {
			/*
			 * Authenticated visitor. Unless pre-verified,
			 * check that the contact belongs to this $owner_id
			 * and load the groups the visitor belongs to.
			 * If pre-verified, the caller is expected to have already
			 * done this and passed the groups into this function.
			 */

			if (!$remote_verified) {
				$cid = 0;

				foreach (\Friendica\Core\Session::get('remote', []) as $visitor) {
					if ($visitor['uid'] == $owner_id) {
						$cid = $visitor['cid'];
						break;
					}
				}

				if ($cid && DBA::exists('contact', ['id' => $cid, 'uid' => $owner_id, 'blocked' => false])) {
					$remote_verified = true;
					$groups = Group::getIdsByContactId($cid);
				}
			}

			if ($remote_verified) {
				$gs = '<<>>'; // should be impossible to match

				if (is_array($groups)) {
					foreach ($groups as $g) {
						$gs .= '|<' . intval($g) . '>';
					}
				}

				$sql = sprintf(
					" AND ( NOT (deny_cid REGEXP '<%d>' OR deny_gid REGEXP '%s')
					  AND ( allow_cid REGEXP '<%d>' OR allow_gid REGEXP '%s' OR ( allow_cid = '' AND allow_gid = '') )
					  )
					",
					intval($cid),
					DBA::escape($gs),
					intval($cid),
					DBA::escape($gs)
				);
			}
		}
		return $sql;
	}

}