//############################################################################

//# FILE Telnet.java

//# VERSION 0.94

//# DATE: 4/27/96

//# AUTHOR:  Bret Dahlgren (bret@lm.com) based on dummy telnet terminal code

//#          by Jamie Cameron (jameson@ncb.gov.sg)

//#

//# Ver. 0.94   4/27/96 Couple of changes for IAC and a new parameter.

//#                   Fixed up IAC ECHO call and terminal emulation will

//#                   be sent if ANSI is not acceptable.  Probably will

//#                   have to revisit this. Also now send correct value

//#                   for terminal size.

//#                   NEW parameter:

//#                   <param name="fields" value="OFF">

//#                   If value == "OFF" the Host, Port, and Emulation fields

//#                   will not be shown locking those values to those passed

//#                   as parameters.

//# Ver. 0.93   4/12/96 The platform specific bugs are starting to show.

//#                   Windows NT and BSD/OS think the width of the characters

//#                   are twice what they really are. Cut them in half. If 

//#                   this bug is fixed the change will be bypassed.

//#                   NT was acting strangely by not showing the last two

//#                   characters on the screen.  I put in a

//#                   System.out.println("") and the problem went away.  This

//#                   is a stop gap measure and will be taken out when a

//#                   real solution is found or the bug is fixed.

//#                   I was able to fix up the top of the screen for BSD/OS

//#                   and Windows NT so all the buttons appear now.  Please

//#                   send me screen shots of your telnet with your os.name

//#                   if you can't see the connect and disconnect buttons. 

//# Ver. 0.91a  3/14/96 Telnet IAC added Authentication Option code.  Expect

//#                   a few of these changes while other people try it with

//#                   their particular telnet daemons.

//# Ver. 0.91   3/12/96 Found a way to get around the period problem.  

//#                   Use KeyUp to catch the period keys.

//# Ver. 0.90   2/28/96 Initial release.

//#

//# Copyright (c) 1996 Bret G. Dahlgren, All Rights Reserved.

//############################################################################

import java.net.*;

import java.awt.*;

import java.io.*;

import java.lang.*;



//############################################################################

//# CLASS: Telnet

//#   Applet which sets up the Panal and canvas for the Telnet Client and the

//#   input text fields of Host, Port, and Emulator.

//#

//# HTML tag:

//#   <applet code="Telnet.class" width="XXX" height="XXX">

//#   <param name="host" value="XXXX">

//#   <param name="port" value="XXXX">

//#   <param name="emulation" value="XXXX">

//#   <param name="fields" value="XXX">

//#   </applet>

//#

//# HTML tag NOTES

//#   width - width of the applet.  For 80 chars (on Win95) in Courier 11 use 560.

//#   height - height of the applet.  For 25 lines (on Win95) in Courier 11 use 390.

//#   host - host to connect to initially.  For Netscape use you should have

//#          the name of the host the code is on so there is not a socket

//#          security error on startup.  May be host name or IP address.

//#   port - port to connect to initially.  Standard telnet port is 23.

//#   emulation - The emulation to use initially.  This emulation is loaded

//#          on the fly.  ANSI is loaded first even if you are not using it

//#          for initializing purposes.

//#   fields - boolean value.  if fields == "OFF" the host, port, and emulation

//#          fields will not appear on the applet.

//#

//# DESIGN NOTES:

//#   This applet still runs even if you leave the page.  I've noticed a need

//#   to leave the page while it's still receiving data to look at something

//#   else and come back to my same session.  So start() only starts a session

//#   on the first time it comes up.  If you resize the page or leave and come

//#   back the session will still be up.

//#

//# METHOD: init

//#   first procedure called.  Grabs parameters. Sets up Layout and creates

//#   the Canvas for the telnet session.

//#

//# METHOD: con

//#    Tells the telnet client to disconnect and reconnect the new host.

//#

//# METHOD: start

//#    Connects on initialization, but won't reconnect on every start() 

//#    call which happens on changing pages or even resizing Netscape.

//#

//# METHOD: action

//#	 Gets the read from the two buttons and acts accordingly.

//#

//############################################################################

public class Telnet extends java.applet.Applet

{

 String hoststr, portstr,emstr; // parameters giving host & port

 String fieldson;

 Panel controls;

 TelnetClient tn;              // telnet component

 TextField hostfield;

 TextField portfield;

 TextField emfield;

 Button connect, disconnect;

 boolean firsttime = true;

 String UserOs = System.getProperty("os.name");



 public void init()

   {

   // Set up interface

   hoststr = getParameter("host");

   portstr = getParameter("port");

   emstr   = getParameter("emulation");

   fieldson = getParameter("fields");



   if (hoststr == null) hoststr = "127.0.0.1";

   if (portstr == null) portstr = "23";

   if (emstr == null) emstr = "ANSI";

   if (fieldson == null) fieldson = "ON";



   // Create interface

     setLayout(new BorderLayout());

     add("Center",tn = new TelnetClient());

     add("North",controls = new Panel());

     controls.setLayout(new FlowLayout());



   if (fieldson.compareTo("OFF") == 0)

     {

     controls.add(connect = new Button("Connect"));

     controls.add(disconnect = new Button("Disconnect"));

     return;

     }



   if (UserOs.compareTo("Windows NT") == 0)

     {

     controls.add(new Label("Host "));

     controls.add(hostfield = new TextField(10));

     hostfield.setText(hoststr);

     controls.add(new Label("Port "));

     controls.add(portfield = new TextField(3));

     portfield.setText(portstr);

     controls.add(new Label("Emulation "));

     controls.add(emfield = new TextField(7));

     emfield.setText(emstr);

     controls.add(connect = new Button("Connect"));

     controls.add(disconnect = new Button("Disconnect"));

     }

   else if (UserOs.compareTo("BSD/OS") == 0)

     {

     controls.add(new Label("Host"));

     controls.add(hostfield = new TextField(10));

     hostfield.setText(hoststr);

     controls.add(new Label("Port"));

     controls.add(portfield = new TextField(2));

     portfield.setText(portstr);

     controls.add(new Label("Emulation"));

     controls.add(emfield = new TextField(4));

     emfield.setText(emstr);

     controls.add(connect = new Button("Connect"));

     controls.add(disconnect = new Button("Disconnect"));



     }

   else

     {

     controls.add(new Label("Host "));

     controls.add(hostfield = new TextField(15));

     hostfield.setText(hoststr);

     controls.add(new Label("Port "));

     controls.add(portfield = new TextField(3));

     portfield.setText(portstr);

     controls.add(new Label("Emulation "));

     controls.add(emfield = new TextField(12));

     emfield.setText(emstr);

     controls.add(connect = new Button("Connect"));

     controls.add(disconnect = new Button("Disconnect"));

     }

   }



 public void con()

   {

   int port;

   // Don't try if the telnet client doesn't exist.

   if (tn == null)

     return;

  

   tn.disconnect();



   if (fieldson.compareTo("OFF") == 0)

     {

     if (portstr.equals(""))

       port = 23;

     else 

       port =  Integer.parseInt(portstr);



     tn.connect(hoststr,port, emstr);

     return;

     }



   // Integer.parseInt blows up if the string is null, that's not right :-)

   if (portfield.getText().equals(""))

     port = 23;

   else {

     port =  Integer.parseInt(portfield.getText());

     }

   tn.connect(hostfield.getText(),port, emfield.getText());

   }



 public void start()

   {



   if (firsttime == true)

   con();



   firsttime = false;

   }



 public boolean action(Event e, Object arg)

   {

   if (e.target == connect)

     con();

   else if (e.target == disconnect)

     tn.disconnect();

   return true;

   }

}





//############################################################################

//# CLASS: TelnetClient

//#   Actual class which does the telnet work.  It connects to the given host

//#   and port.  It also loads the emulation class.

//#

//# METHOD: reshape

//#   called once in Netscape to size the applet.  Appletviewer can be resized

//#   and this is called everytime the size is changed.

//#

//# METHOD: connect

//#   called from Telnet to connect to the host and also loads the emulation

//#   class givenemul.

//#

//# METHOD: disconnect

//#   stops the TelnetClient thread and kills the connection.

//#

//# METHOD: clearch

//#   calls the emulation clearscreen and repaints the screen.

//#

//# METHOD: keyDown

//#   called on a key press.  calls the emulator.transmitch which will send

//#   it in the out stream after any changes the emulator might make.

//#

//# METHOD: keyUp

//#   used to catch the period key '.' because of the bug in keyDown.

//#

//# METHOD: mouseDown

//#   gets focus for keyDown when mouse is clicked in applet.

//#

//# METHOD: paint

//#   called when screen needs refreshed.

//#

//# METHOD: update

//#   overrides super.update so there is no flicker.

//#

//# METHOD: run

//#   reads and displays the input stream in an endless loop.

//#

//# METHOD: readch

//#   reads the stream one character at a time.  Used in rare occasion.

//#

//# METHOD: readstream

//#   reads the input stream into a byte array.

//#

//# METHOD: shutdown

//#   terminates the connection.

//#

//# METHOD: displaystream

//#   calls the emulator to display the stream.  if a telnet command 

//#   is seen telnetparse is called.  Note that in a byte array anything

//#   after 127 is negative so adjustments were made.

//#

//# METHOD: telnetparse

//#   responds to telnet commands that are sent on initial connection.

//#

//# METHOD: display

//#   displays a string to the telnet window.

//#

//# METHOD: displaych

//#   displays a character to the telnet window. the telnet code is not used

//#   anymore.

//#

//# METHOD: transmit

//#   transmits a string through the pipe.

//#

//# METHOD: transmitch

//#   transmits a character through the pipe.

//#

//############################################################################

class TelnetClient extends java.awt.Canvas implements Runnable

 {

  boolean debug = false;

  String host;                    // remote host

  int port;                       // remote port

  Socket s;                       // connection to remote host

  InputStream in;                 // data from other end

  OutputStream out;               // data to other end

  Thread th;                      // thread for reading data

  Font fn;                        // current font

  Image back;                // backing image

  int x, y;                   // cursor position (in chars)

  int chw,chh;                    // size of a char (in pixels)

  int chd;                        // offset of char from baseline

  int width,height;            // size of applet (in pixels)

  int w,h;                        // size of applet (in chars)

  Graphics gr,bgr;            // front and back graphics

  Emulation emulator;



  String term = "ANSI";  // what this terminal claims to be

  String Cterm;            // class emulator

  boolean firstterm = true;

  boolean echo;      // echo keys sent?

  boolean periodwork = false;

  String UserOs = System.getProperty("os.name");  // For platform specific bugs.





  public void reshape(int nx, int ny, int nw, int nh)

    {



    if (nw != width || nh != height) {

      width = nw;

      height = nh;

	   

      // Open font

      gr = getGraphics();

      fn = new Font("Courier",Font.PLAIN,11);

      if (fn != null) gr.setFont(fn);

      FontMetrics fnm = gr.getFontMetrics();

      chw = fnm.getMaxAdvance();

      chh = fnm.getHeight();

      chd = fnm.getDescent();



      // kludge for Windows NT and others which have too big widths

      if (chw + 1 >= chh)

        {

        chw = (chw + 1) / 2;

        }





      // work out size of drawing area

      h = nh / chh;

      w = nw / chw;



      // setup backing image

      back = createImage(width, height);

      bgr = back.getGraphics();

      bgr.setFont(fn);



      Emulation.initClass(this);



      try {



        emulator = (Emulation)Class.forName("ANSI").newInstance();

        }



      catch(Exception e) {

        e.printStackTrace();

        }



      clearch();

      }



    super.reshape(nx,ny,nw,nh);

    }



  void connect(String givenhost, int givenport, String givenemul)

    {

    host = givenhost; port = givenport;



    if (givenemul != Cterm )

      {

      try {

        emulator = (Emulation)Class.forName(givenemul).newInstance();

        }

      catch(Exception e) {

        e.printStackTrace();

        }

      Cterm = givenemul;

      }



    if (debug) System.out.println("Height = "+String.valueOf(h));

    if (debug) System.out.println("Width  = "+String.valueOf(w));



    // reset display

    clearch();

    echo = false;

    requestFocus();

    firstterm = true;



    // Open connection

    try {

      try {

        try {

          if ((s = new Socket(host,port)) == null) {

            display("Failed to connect to host "+host+"\n");

            return;

            }

          }

        catch(UnknownHostException e) {

          display("Host " + host + " not found\n");

          return;

          }

        }

      catch(IOException e) {

        display("Failed to connect to host "+host+"\n");

        return;

        }

      }

    catch (Exception e) {

      display("Security violation on socket for host "+host+"\n");

      return;

      }



    try {

      in = s.getInputStream();

      out = s.getOutputStream();

      }

    catch(IOException e) {

      if (debug) System.out.println("Failed to get stream from socket");

      System.exit(5);

      }

    display("Connected to "+host+"\n");

    if (debug) System.out.println("Connected to host");



    // Begin thread for reading data

    th = new Thread(this);

    th.start();

    }



  void disconnect()

  {

  if (th != null) {

    display("\nDisconnected from "+host+"\n");

    th.stop();

    th = null;

    s = null; in = null; out = null;

    }

  }



  void clearch()

  {

  emulator.clearscreen();

  repaint();

  return;

  }



  // keyDown

  // Called on keypress

  public boolean keyDown(Event e, int k)

    {

    if (out != null) {

      int kp = e.key;



      if (kp == '.')

        periodwork = true;



      // if ((kp == '`') && (periodwork == false)) kp = '.'; // bug in keyDown



      if (debug) System.out.println("Pressed key " + String.valueOf(kp));



      emulator.transmitch((char)kp);



      if (echo) {

        if (debug) System.out.println("Echo'd "+String.valueOf(kp));

        displaych((char)kp);

        }

      }

    return true;

    }





// this is a kludge in order to get the period key when there is a bug in keyDown

  public boolean keyUp(Event e, int k)

    {

    if (periodwork == true) return true;



    if (k != '.') return true;



    if (out != null) {



      if (debug) System.out.println("Pressed key " + String.valueOf(k));



      emulator.transmitch((char)k);



      if (echo) {

        if (debug) System.out.println("Echo'd "+String.valueOf(k));

        displaych((char)k);

        }

      }

    return true;



    }







  public boolean mouseDown(Event e, int x, int y)

    {

    requestFocus();

    //repaint();

    return true;

    }



  public void paint(Graphics g)

    {

    g.drawImage(back,0,0,this);

    }



   public void update(Graphics g)

     {

     g.drawImage(back,0,0,this);

     }



   public void run()

     {

     byte b[] = new byte[2000];

     int len;



     while(true)

       {

       len = readstream(b);

       displaystream(b,len);

       }

     }



   char readch()

     {

     int c = 0;

     try

       c = in.read();

     catch(IOException e)

       shutdown();

     if (c == -1) shutdown();

     if (debug) System.out.println("Got char "+String.valueOf(c)+" = "+String.valueOf((char)c));

     return (char)c;

     }



   int readstream(byte[] b)

     {

     int len = 0;

     try

       len = in.read(b);

     catch(IOException e)

       shutdown();

     if (len == -1) shutdown();

     return len;

     }



   // shutdown

   // Terminate connection

   void shutdown()

     {

     display("\nConnection closed\n");

     s = null; in = null; out = null;

     Thread.currentThread().stop();

     }



   // Display a stream of data

   void displaystream( byte b[], int len)

     {

     for (int i = 0; i <len; i++)

       {

       if (b[i] == 255 - 256)

         telnetparse(b,i,len);

       }

     emulator.displaybytes(b, len);

     if (UserOs.compareTo("Windows NT") == 0)

       {

       System.out.println("");

	    }



     repaint();

     }





   void telnetparse(byte b[], int index, int len)

     {

     char cmd;

     char opt;

 

     if ( index+1 > len - 1)

       {

       cmd = readch();

       if (cmd == 240)

           {

           return;

           }

       opt = readch(); 

       }

     else

       {

       if (b[index+1] < 0)

         cmd = (char)((int)b[index+1] + 256);

       else

         cmd = (char)b[index+1];



       if (cmd == 240)

           {

           return;

           }



       if (index+2 > len - 1)

         {

         opt = readch();

         }

       else

         {

         if (b[index+2] < 0)

           opt = (char)((int)b[index+2] + 256);

         else

           opt = (char)b[index+2];

         }

       }



     if (debug) System.out.println("read opt " + (int)opt + " and cmd " + (int)cmd);



       switch(opt) {

         case 1:  // echo

            if (cmd == 251)

              {

              transmitch((char)255);

              transmitch((char)253);

              transmitch((char)1);

              echo = false;

              }

            else if (cmd == 252)

              {

              transmitch((char)255);

              transmitch((char)254);

              transmitch((char)1);

              echo = true;

              }

            else if (cmd == 253)

              {

              transmitch((char)255);

              transmitch((char)251);

              transmitch((char)1);

              }



            break;



         case 3: // supress go-ahead

            transmitch((char)255);

            transmitch((char)253);

            transmitch((char)opt);

            break;



         case 32: // Terminal speed

            transmitch((char)255);

            transmitch((char)251);

            transmitch((char)32);

            transmitch((char)255);

            transmitch((char)250);

            transmitch((char)32);

            transmitch((char)0);

            transmit("38400,38400");

            transmitch((char)255);

            transmitch((char)240);



            break;



         case 35: // X display location

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)35);

            break;



         case 33: // Remote Flow control

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)33);

            break;



         case 31: // Window size

            if (cmd == 253) {

              // IAC WILL terminal-type

              transmitch((char)255);

              transmitch((char)251);

              transmitch((char)31);



              transmitch((char)255);

              transmitch((char)250);

              transmitch((char)31);

              char stemp =(char)(w / 256);

              transmitch(stemp);

              stemp = (char)(w % 256);

              transmitch(stemp);

              stemp = (char)(h / 256);

              transmitch(stemp);

              stemp = (char)(h % 256);

              transmitch(stemp);

              transmitch((char)255);

              transmitch((char)240);

              }

            break;



         case 39:

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)39);

            break;



         case 36: // Environment option

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)36);

            break;



         case 24: // terminal type

            if (cmd == 253) {

              // IAC WILL terminal-type

              transmitch((char)255);

              transmitch((char)251);

              transmitch((char)24);

					}

            else if (cmd == 250) {

              // IAC SB terminal-type IS <term> IAC SE

              transmitch((char)255);

              transmitch((char)250);

              transmitch((char)24);

              transmitch((char)0);

              if (firstterm == true)

                {

                transmit(term);

                firstterm = false;

                }

              else

                {

                transmit(Cterm);

                }



              transmitch((char)255);

              transmitch((char)240);

              }

            break;



         case 37: // Authentication

            if (cmd == 253) {

              // IAC WILL terminal-type

              transmitch((char)255);

              transmitch((char)251);

              transmitch((char)37);



              // IAC SB 0000 IAC SE

              transmitch((char)255);

              transmitch((char)250);

              transmitch((char)37);

              transmitch((char)0);

              transmitch((char)0);

              transmitch((char)0);

              transmitch((char)0);

              transmitch((char)255);

              transmitch((char)240);

              }

            break;



         default: // Catch all

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)opt);

            break;



         }

     }





   // display

   // Display a string in the telnet window

   void display(String str)

   {

   int i;

   for(i=0; i<str.length(); i++)

     displaych(str.charAt(i));

   }



   // displaych

   // Display one character at the current cursor position

   void displaych(char c)

     {



     if ( c < 128) {

       // Some printable character

       emulator.displaych(c);

       repaint();

       }

     else if (c == 255) {

       // Telnet IAC

       char cmd = readch();

       if (cmd == 240)

           {

           return;

           }

       char opt = readch();

	    switch(opt) {

         case 1:  // echo

             if (cmd == 251) echo = false;

             else if (cmd == 252) echo = true;

             break;

	  

         case 3:  // supress go-ahead

            break;

	  

         case 32:

            transmitch((char)255);

            transmitch((char)251);

            transmitch((char)32);

            transmitch((char)255);

            transmitch((char)250);

            transmitch((char)32);

            transmitch((char)0);

            transmit("38400,38400");

            transmitch((char)255);

            transmitch((char)240);

	  

            break;

	  

         case 35:

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)35);

            break;

	  

         case 33:

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)33);

            break;

	  

         case 31:

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)31);

            break;

	  

         case 39:

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)39);

            break;

	  

         case 36:

            transmitch((char)255);

            transmitch((char)252);

            transmitch((char)36);

            break;

	  

         case 24: // terminal type

            if (cmd == 253) {

              // IAC WILL terminal-type

              transmitch((char)255);

              transmitch((char)251);

              transmitch((char)24);

	  

              // IAC SB terminal-type IS <term> IAC SE

              transmitch((char)255);

              transmitch((char)250);

              transmitch((char)24);

              transmitch((char)0);

              transmit(term);

              transmitch((char)255);

              transmitch((char)240);

              }

            else if (cmd == 250) {

              while(readch() != 240);

              }

            break;

         }

       }

     }



   void transmit(String str)

     {

     int i;



     for(i=0; i<str.length(); i++)

       transmitch(str.charAt(i));

     }



   void transmitch(char c)

     {

     if (c == '\n') transmitch('\r');

     try {

       out.write((int)c);

       out.flush();

       }

     catch(IOException e);

   

     if (debug) System.out.println("Sent char " + String.valueOf((int)c) + " = " + String.valueOf(c));

     }

}