nextcloud/lib/private/Net/IpAddressClassifier.php

<?php

declare(strict_types=1);

/*
 * @copyright 2022 Christoph Wurst <christoph@winzerhof-wurst.at>
 *
 * @author 2022 Christoph Wurst <christoph@winzerhof-wurst.at>
 *
 * @license GNU AGPL version 3 or any later version
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * 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
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

namespace OC\Net;

use IPLib\Address\IPv6;
use IPLib\Factory;
use IPLib\ParseStringFlag;
use Symfony\Component\HttpFoundation\IpUtils;
use function filter_var;

/**
 * Classifier for IP addresses
 *
 * @internal
 */
class IpAddressClassifier {
	private const LOCAL_ADDRESS_RANGES = [
		'100.64.0.0/10', // See RFC 6598
		'192.0.0.0/24', // See RFC 6890
	];

	/**
	 * Check host identifier for local IPv4 and IPv6 address ranges
	 *
	 * Hostnames are not considered local. Use the HostnameClassifier for those.
	 */
	public function isLocalAddress(string $ip): bool {
		$parsedIp = Factory::parseAddressString(
			$ip,
			ParseStringFlag::IPV4_MAYBE_NON_DECIMAL | ParseStringFlag::IPV4ADDRESS_MAYBE_NON_QUAD_DOTTED
		);
		if ($parsedIp === null) {
			/* Not an IP */
			return false;
		}
		/* Replace by normalized form */
		if ($parsedIp instanceof IPv6) {
			$ip = (string)($parsedIp->toIPv4() ?? $parsedIp);
		} else {
			$ip = (string)$parsedIp;
		}

		if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
			/* Range address */
			return true;
		}
		if (IpUtils::checkIp($ip, self::LOCAL_ADDRESS_RANGES)) {
			/* Within local range */
			return true;
		}

		return false;
	}
}