1 files changed, 61 insertions, 0 deletions
diff --git a/lib/private/Net/IpAddressClassifier.php b/lib/private/Net/IpAddressClassifier.php
new file mode 100644
index 00000000000..b73d41fd79b
--- /dev/null
+++ b/lib/private/Net/IpAddressClassifier.php
@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2022 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+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(
+			$ip,
+			ParseStringFlag::IPV4_MAYBE_NON_DECIMAL | ParseStringFlag::IPV4ADDRESS_MAYBE_NON_QUAD_DOTTED | ParseStringFlag::MAY_INCLUDE_ZONEID
+		);
+		if ($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;
+	}
+}