HostDnsDriver.php: add

inc/Data/Driver/Dns/HostDnsDriver.php

@@ -0,0 +1,43 @@
+<?php
+namespace Vichan\Data\Driver\Dns;
+
+
+/**
+ * Relies on the `host` command line executable.
+ */
+class HostDnsDriver implements DnsDriver {
+	private int $timeout;
+
+	private static function matchOrEmpty(string $pattern, string $subject): array {
+		$ret = \preg_match_all($pattern, $subject, $out);
+		if ($ret === false || $ret === 0) {
+			return [];
+		}
+		return $out[1];
+	}
+
+	public function __construct(int $timeout) {
+		$this->timeout = $timeout;
+	}
+
+	public function nameToIPs(string $name): ?array {
+		$ret = shell_exec_error("host -W {$this->timeout} {$name}");
+		if ($ret === false) {
+			return null;
+		}
+
+		$ipv4 = self::matchOrEmpty('/has address ([^\s]+)/', $ret);
+		$ipv6 = self::matchOrEmpty('/has IPv6 address ([^\s]+)/', $ret);
+		return \array_merge($ipv4, $ipv6);
+	}
+
+	public function IPToNames(string $ip): ?array {
+		$ret = shell_exec_error("host -W {$this->timeout} {$ip}");
+		if ($ret === false) {
+			return null;
+		}
+
+		$names = self::matchOrEmpty('/domain name pointer ([^\s]+)\./', $ret);
+		return \array_map(fn($n) => \strtolower(\rtrim($n, '.')), $names);
+	}
+}