PHP 查询一条 SRV 记录

Question

我运行一个 Minecraft 网站，目前在使用查询协议时，它无法处理 SRV 记录。

我只是想知道有没有办法获取 SRV 记录指向的 ip 和端口。

E.g: mc.lunarphase.co.uk => 192.198.91.238:64759

Answer 1

您可以使用 dns_get_record。

$result = dns_get_record("_http._tcp.mxtoolbox.com", DNS_SRV);
print_r($result);

打印出来的：

Array
(
    [0] => Array
        (
            [host] => _http._tcp.mxtoolbox.com
            [class] => IN
            [ttl] => 2409
            [type] => SRV
            [pri] => 10
            [weight] => 100
            [port] => 80
            [target] => mxtoolbox.com
        )

)

Answer 2

最简单的方法可能是使用 dig。您可以直接使用套接字，但这样更容易（恕我直言）：

function getDNS($hostname, $type='') {
        $records=`dig +noall +answer $hostname $type`;
        $records=explode("\n",$records);
        $res_hostname='';
        $port=0;

        foreach ($records as $record) {
                preg_match_all('/([^\s]+)\s*/',$record, $matches);
                if (is_array($matches) && is_array($matches[1]) && count($matches[1]) > 3) {
                        switch (strtoupper($matches[1][3])) {
                        case 'SRV':
                                if (count($matches[1]) > 6) {
                                        $port=$matches[1][6];
                                        $res_hostname=$matches[1][7];
                                }
                                break;
                        case 'A':
                        case 'CNAME':
                                if (count($matches[1]) > 3) {
                                        $res_hostname=$matches[1][4];
                                }
                                break;
                        }
                        if (!empty($res_hostname) && substr($res_hostname, -1) == '.') break; // if it's a cname, we've probably already got the ip, so keep going just in case (but we might not so don't count on it!)
                }
        }
        if (substr($res_hostname, -1) == '.') { // we have more resolving to do
                $res_hostname=getDNS(trim($res_hostname, '. '));
        }

        if (empty($res_hostname)) die('Failed to lookup IP for ' . (!empty($type) ? '(' . $type .' record) ' : '' ) . $hostname . PHP_EOL);
        if (empty($port)) return $res_hostname;
        return $res_hostname . ':' . $port;
}
$hostIPPair=getDNS('example.com', 'srv');