1 files changed, 85 insertions, 0 deletions
diff --git a/lib/private/Http/Client/LocalAddressChecker.php b/lib/private/Http/Client/LocalAddressChecker.php
new file mode 100644
index 00000000000..e9c92da4a5c
--- /dev/null
+++ b/lib/private/Http/Client/LocalAddressChecker.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2021, Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @author Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @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\Http\Client;
+
+use OCP\ILogger;
+use OCP\Http\Client\LocalServerException;
+
+class LocalAddressChecker {
+	/** @var ILogger */
+	private $logger;
+
+	public function __construct(ILogger $logger) {
+		$this->logger = $logger;
+	}
+
+	public function ThrowIfLocalIp(string $ip) : void {
+		if ((bool)filter_var($ip, FILTER_VALIDATE_IP) && !filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
+			$this->logger->warning("Host $ip was not connected to because it violates local access rules");
+			throw new LocalServerException('Host violates local access rules');
+		}
+
+		// Also check for IPv6 IPv4 nesting, because that's not covered by filter_var
+		if ((bool)filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) && substr_count($ip, '.') > 0) {
+			$delimiter = strrpos($ip, ':'); // Get last colon
+			$ipv4Address = substr($ip, $delimiter + 1);
+
+			if (!filter_var($ipv4Address, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
+				$this->logger->warning("Host $ip was not connected to because it violates local access rules");
+				throw new LocalServerException('Host violates local access rules');
+			}
+		}
+	}
+
+	public function ThrowIfLocalAddress(string $uri) : void {
+		$host = parse_url($uri, PHP_URL_HOST);
+		if ($host === false || $host === null) {
+			$this->logger->warning("Could not detect any host in $uri");
+			throw new LocalServerException('Could not detect any host');
+		}
+
+		$host = strtolower($host);
+		// Remove brackets from IPv6 addresses
+		if (strpos($host, '[') === 0 && substr($host, -1) === ']') {
+			$host = substr($host, 1, -1);
+		}
+
+		// Disallow localhost and local network
+		if ($host === 'localhost' || substr($host, -6) === '.local' || substr($host, -10) === '.localhost') {
+			$this->logger->warning("Host $host was not connected to because it violates local access rules");
+			throw new LocalServerException('Host violates local access rules');
+		}
+
+		// Disallow hostname only
+		if (substr_count($host, '.') === 0 && !(bool)filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
+			$this->logger->warning("Host $host was not connected to because it violates local access rules");
+			throw new LocalServerException('Host violates local access rules');
+		}
+
+		$this->ThrowIfLocalIp($host);
+	}
+}