如何处理UDP dns请求

Question

我在一个简单的DNS服务器上工作。我也喜欢自己做，因为它也是一种学习经验。但是，我一直试图了解DNS请求。问题是，数据（作为字符串）出现了一些我不知道如何处理的额外的不可读字符。我什至期望像“ WhoIs google.com响应代码1234”之类的内容，但能在屏幕截图中看到 caption after run 还有我的源代码。

package com.donsoft.ambient;

import java.net.*;

public class Dns {

    public static void main(String[] args){
        try{
            DatagramSocket sock = new DatagramSocket(53);
            //Now for reading the packets
            while(true){
                byte[] buffer = new byte[256]; //I think that size is good
                DatagramPacket in = new DatagramPacket(buffer, buffer.length);
                sock.receive(in);
                String data = new String(in.getData());
                if(data!=null){
                    process(in);
                }
                Thread.sleep(200); //To reduce CPU usage
            }
        }catch(Exception error){error.printStackTrace();}
    }
    public static void process(DatagramPacket pack){
        //I just print it out
        //But this is supposed to read the query and respond
        //Am hooked at the point of formatting the data
        String data = new String(pack.getData());
        System.out.println(data);
    }

}