LibcDnsDriver.php: add

inc/Data/Driver/Dns/LibcDnsDriver.php

@@ -0,0 +1,40 @@
+<?php
+namespace Vichan\Data\Driver\Dns;
+
+
+/**
+ * For the love of god never use this implementation if you can.
+ */
+class LibcDnsDriver implements DnsDriver {
+	public function __construct(int $timeout) {
+		// Try to impose a very frail timeout https://www.php.net/manual/en/function.gethostbyname.php#118841
+		\putenv("RES_OPTIONS=retrans:1 retry:1 timeout:{$timeout} attempts:1");
+	}
+
+	/**
+	 * For the love of god never use this.
+	 * https://www.php.net/manual/en/function.gethostbynamel.php#119535
+	 */
+	public function nameToIPs(string $name): ?array {
+		// Add a trailing dot to not return the loopback address on failure
+		// https://www.php.net/manual/en/function.gethostbynamel.php#119535
+		$ret = \gethostbynamel("{$name}.");
+		if ($ret === false) {
+			return null;
+		}
+		return $ret;
+	}
+
+	/**
+	 * For the love of god never use this.
+	 * https://www.php.net/manual/en/function.gethostbyaddr.php#57553
+	 */
+	public function IPToNames(string $ip): ?array {
+		$ret = \gethostbyaddr($ip);
+		if ($ret === $ip || $ret === false) {
+			return null;
+		}
+		// Case extravaganza: https://www.php.net/manual/en/function.gethostbyaddr.php#123563
+		return [ \strtolower($ret) ];
+	}
+}