Program for Domain Name System (DNS) using TCP

Client:

import java.io.*;

import java.net.*;

import java.util.*;

class Clientdns

{

            public static void main(String args[])

            {

            try

            {         

                        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));

                        Socket clsct=new Socket("127.0.0.1",139);

                        DataInputStream din=new DataInputStream(clsct.getInputStream());

                        DataOutputStream dout=new DataOutputStream(clsct.getOutputStream());

                        System.out.println("Enter the Address (IP or DOMAIN NAME):");

                        String str1=in.readLine();

                        dout.writeBytes(str1+'\n');

                        String str=din.readLine();

                        System.out.println("DOMAIN NAME or IP: "+str);            

                        clsct.close();

            }

            catch (Exception e)

            {

            System.out.println(e);

            }

            }

}

Server:

import java.io.*;

import java.net.*;

import java.util.*;

class Serverdns

{

            public static void main(String args[])

            {

            try

            {

                        ServerSocket obj=new ServerSocket(139);

                        Socket obj1=obj.accept();

                        while(true)

                        {

                                    DataInputStream din=new DataInputStream(obj1.getInputStream());

                                    DataOutputStream dout=new DataOutputStream(obj1.getOutputStream());

                                    String str=din.readLine();

                                    String ip[]={"165.165.80.80","165.165.79.1"};

                                    //String mac[]={"6A:08:AA:C2","8A:BC:E3:FA"};

                                    String name[]={"www.skcet.ac.in","www.skcetlib.ac.in"};

                                    for(int i=0;i<ip.length;i++)

                                    {

                                                if(str.equals(ip[i]))

                                                {

                                                            dout.writeBytes(name[i]+'\n');

                                                            break;

                                                }

                                                else if(str.equals(name[i]))

                                                {

                                                            dout.writeBytes(ip[i]+'\n');

                                                            break;

                                                }

                                               

                                    }                     

                                    obj.close();

                        }

                       

            }

            catch(Exception e)

            {

                        System.out.println(e);

            }

            }

}

Output:

E:\networks>java Clientdns

Enter the Address (IP or DOMAIN NAME):

www.skcet.ac.in

DOMAIN NAME or IP: 165.165.80.80

E:\networks>java Clientdns

Enter the Address (IP or DOMAIN NAME):

165.165.79.1

DOMAIN NAME or IP: www.skcetlib.ac.in