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/*******************************************************************************
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 * File: P2_Client.java
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 * Author: Ira W. Snyder (devel@irasnyder.com)
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 * License: GNU General Public License v2
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 * Class: CS380 - Computer Networking
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 *
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 * Assignment: Project #2
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 * Date Last Modified: 2006-02-05
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 *
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 * Purpose: Implement a simple client allowing the user to send datagrams
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 * to P2_Server, which will decode them from 4B to 5B encoding. The client
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 * will retransmit any packets that do not recieve a reply.
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 ******************************************************************************/
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import java.io.*;
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import java.io.*;
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import java.net.*;
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import java.net.*;
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import java.util.*;
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import java.util.*;
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    private static int soTimeout = 3000; // 3000 ms timeout = 3 sec
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    private static int soTimeout = 3000; // 3000 ms timeout = 3 sec
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    private static DatagramSocket socket;
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    private static DatagramSocket socket;
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    private static DatagramPacket packet;
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    private static DatagramPacket packet;
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    private static int portNumber = 1337;
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    private static int portNumber = 1337;
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    /**
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     * Method: readPacket()
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     * Purpose: Read a packet on the currently opened DatagramSocket,
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     * and return it as a String.
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     */
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    public static String readPacket (int maxlen)
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    public static String readPacket (int maxlen)
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    {
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    {
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        byte[] buf = new byte[maxlen];
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        byte[] buf = new byte[maxlen];
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        packet = new DatagramPacket (buf, buf.length);
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        packet = new DatagramPacket (buf, buf.length);
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            return null;
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            return null;
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        }
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        }
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        return new String (buf, 0, packet.getLength()/*- 1*/);
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        return new String (buf, 0, packet.getLength()/*- 1*/);
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    }
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    }
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    /**
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     * Method: writePacket()
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     * Purpose: Send a packet to localhost:portNumber.
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     */
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    public static boolean writePacket (String msg) throws Exception
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    public static boolean writePacket (String msg) throws Exception
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    {
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    {
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        InetAddress address = InetAddress.getLocalHost();
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        InetAddress address = InetAddress.getLocalHost();
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        int port = portNumber;
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        int port = portNumber;
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        }
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        }
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        return true;
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        return true;
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    }
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    }
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    /**
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     * Method: guaranteedTransmit()
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     * Purpose: A wrapper around readPacket() and writePacket() that implements
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     * a reliable transmit mechanism. It allows you to specify a maximum number
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     * of times to try resending a packet.
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     */
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    public static String guaranteedTransmit (String msg, int maxlen, int maxRetries) throws Exception
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    {
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        String reply = null;
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        int retries = 0;
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        writePacket (msg);
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        reply = readPacket (maxlen);
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        while (reply == null && retries < maxRetries)
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        {
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            System.err.println ("Packet lost, retransmitting...");
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            writePacket (msg);
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            reply = readPacket (maxlen);
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            retries++;
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        }
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        return reply;
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    }
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    /**
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     * Method: main()
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     * Purpose: This will accept input from the user, and attempt to send it
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     * to the corresponding server, which will convert the messages from 4B
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     * to 5B encoding.
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     */
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    public static void main (String[] args) throws Exception
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    public static void main (String[] args) throws Exception
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    {
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    {
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        int dropHowMany = 0;
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        int dropHowMany = 0;
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        socket = new DatagramSocket();
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        socket = new DatagramSocket();
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        socket.connect (InetAddress.getLocalHost(), portNumber);
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        socket.connect (InetAddress.getLocalHost(), portNumber);
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        } catch (ArrayIndexOutOfBoundsException e) {
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        } catch (ArrayIndexOutOfBoundsException e) {
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            System.err.println ("You need to call the program with \'java P2_Client <num>\'");
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            System.err.println ("You need to call the program with \'java P2_Client <num>\'");
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            System.exit(1);
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            System.exit(1);
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        }
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        }
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        writePacket ("DROP" + dropHowMany);
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        String msg = new String("DROP" + dropHowMany);
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        String reply = guaranteedTransmit (msg, 6, 1);
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        if (!reply.equals(msg))
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        {
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            System.err.println ("Unable to inform the server how often to drop packets");
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            System.exit(1);
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        }
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        System.out.print ("% decode: ");
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        System.out.print ("% decode: ");
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        String msg = kbd.readLine();
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        msg = kbd.readLine();
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        String reply;
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        boolean done = false;
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        boolean done = false;
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        while (!done)
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        while (!done)
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        {
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        {
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            writePacket (msg);
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            reply = readPacket(5);
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            reply = guaranteedTransmit (msg, 6, 1);
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            while (reply == null)
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            {
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                System.out.println ("Packet lost, retransmitting...");
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                writePacket (msg);
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                reply = readPacket(5);
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            }
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            if (reply.equals("QUIT"))
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            if (reply.equals("QUIT"))
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            {
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            {
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                done = true;
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                done = true;
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                continue;
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                continue;
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            System.out.println ("-> reply: " + reply);
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            System.out.println ("-> reply: " + reply);
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            System.out.print ("% decode: ");
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            System.out.print ("% decode: ");
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            msg = kbd.readLine();
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            msg = kbd.readLine();
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        }
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        }
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        // Close the socket
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        socket.close();
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    }
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    }
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}
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}
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