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/*******************************************************************************
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 * File: P1Server.java
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 * Author: Ira W. Snyder (devel@irasnyder.com)
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 * Class: CS380 - Computer Networking
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 *
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 * Assignment: Project #1
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 * Date Last Modified: 2006-01-18
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 *
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 * Purpose: Opens a listening TCP Socket on port 1337. It echoes back
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 *          every packet that it recieves.
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 *
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 ******************************************************************************/
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import java.io.*;
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import java.net.*;
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public class P1Server
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{
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    /* Instance variables */
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    public static final int portNumber = 1337;
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    public static final String exitSeq = "QUIT";
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    /**
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     * Method: main
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     * Purpose: This method creates a listening socket on port 1337 and
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     * accepts the first connection made to it. It then echoes back anything
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     * sent to it, until it recieves a "QUIT", at which point it terminates.
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     */
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    public static void main (String[] args) throws IOException
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    {
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        ServerSocket serverSocket = null;
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        /* Try to open the port for listening */
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        try
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        {
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            serverSocket = new ServerSocket (portNumber);
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        }
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        catch (IOException e)
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        {
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            System.err.println ("Could not listen on port: " + portNumber);
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            System.exit(1);
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        }
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        Socket clientSocket = null;
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        /* Try to accept the first connection that comes in */
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        try
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        {
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            clientSocket = serverSocket.accept();
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        }
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        catch (IOException e)
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        {
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            System.err.println ("Accept failed.");
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            System.exit(1);
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        }
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        /* Set up input and output streams */
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        PrintWriter out = new PrintWriter (clientSocket.getOutputStream(), true);
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        BufferedReader in = new BufferedReader(
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                                new InputStreamReader(
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                                    clientSocket.getInputStream()));
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        /* Use Strings to hold the input and output */
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        String inputLine, outputLine;
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        /* Read input and echo back to output */
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        while ((inputLine = in.readLine()) != null)
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        {
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            /* Echo back what we recieved */
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            out.println (inputLine);
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            System.out.println ("Recieved a packet");
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            /* If we recieve a message to quit, do so. */
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            if (inputLine.equals (exitSeq))
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            {
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                System.out.println ("Recieved exitSeq");
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                break;
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            }
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        }
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        /* Cleanup */
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        out.close();
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        in.close();
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        clientSocket.close();
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        serverSocket.close();
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    }
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}
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