telnetprotocolhandler.java

The Javatm Telnet Application/Applet 很好用的

/*
 * This file is part of "The Java Telnet Application".
 *
 * (c) Matthias L. Jugel, Marcus Meissner 1996-2002. All Rights Reserved.
 *
 * Please visit http://javatelnet.org/ for updates and contact.
 *
 * --LICENSE NOTICE--
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 * --LICENSE NOTICE--
 *
 */

package de.mud.telnet;

import java.io.IOException;
import java.awt.Dimension;

import java.lang.Byte;
/**
 * This is a telnet protocol handler. The handler needs implementations
 * for several methods to handle the telnet options and to be able to
 * read and write the buffer.
 * <P>
 * <B>Maintainer:</B> Marcus Meissner
 *
 * @version $Id: TelnetProtocolHandler.java,v 2.18 2003/11/16 12:37:29 marcus Exp $
 * @author  Matthias L. Jugel, Marcus Meissner
 */
public abstract class TelnetProtocolHandler {
  /** contains the current revision id */
  public final static String ID = "$Id: TelnetProtocolHandler.java,v 2.18 2003/11/16 12:37:29 marcus Exp $";
  
  /** debug level */
  private final static int debug = 0;

  /** temporary buffer for data-telnetstuff-data transformation */
  private byte[] tempbuf = new byte[0];

  /** the data sent on pressing <RETURN>  \n */
  private byte[] crlf = new byte[2];
  /** the data sent on pressing <LineFeed>  \r */
  private byte[] cr = new byte[2];

  /**
   * Create a new telnet protocol handler.
   */
  public TelnetProtocolHandler() {
    reset();

    crlf[0] = 13; crlf[1] = 10;
    cr[0] = 13; cr[1] = 0;
  }

  /**
   * Get the current terminal type for TTYPE telnet option.
   * @return the string id of the terminal
   */
  protected abstract String getTerminalType(); 

  /**
   * Get the current window size of the terminal for the
   * NAWS telnet option.
   * @return the size of the terminal as Dimension
   */
  protected abstract Dimension getWindowSize();

  /**
   * Set the local echo option of telnet.
   * @param echo true for local echo, false for no local echo
   */
  protected abstract void setLocalEcho(boolean echo);

  /**
   * Generate an EOR (end of record) request. For use by prompt displaying.
   */
  protected abstract void notifyEndOfRecord();

  /**
   * Send data to the remote host.
   * @param b array of bytes to send
   */
  protected abstract void write(byte[] b) throws IOException;

  /**
   * Send one byte to the remote host.
   * @param b the byte to be sent
   * @see #write(byte[] b)
   */
  private static byte[] one = new byte[1];
  private void write(byte b) throws IOException {
    one[0] = b;
    write(one);
  }

  /**
   * Reset the protocol handler. This may be necessary after the
   * connection was closed or some other problem occured.
   */
  public void reset() {
    neg_state = 0;
    receivedDX = new byte[256]; 
    sentDX = new byte[256];
    receivedWX = new byte[256]; 
    sentWX = new byte[256];
  }

  // ===================================================================
  // the actual negotiation handling for the telnet protocol follows:
  // ===================================================================

  /** state variable for telnet negotiation reader */
  private byte neg_state = 0;

  /** constants for the negotiation state */
  private final static byte STATE_DATA  = 0;
  private final static byte STATE_IAC   = 1;
  private final static byte STATE_IACSB = 2;
  private final static byte STATE_IACWILL       = 3;
  private final static byte STATE_IACDO = 4;
  private final static byte STATE_IACWONT       = 5;
  private final static byte STATE_IACDONT       = 6;
  private final static byte STATE_IACSBIAC      = 7;
  private final static byte STATE_IACSBDATA     = 8;
  private final static byte STATE_IACSBDATAIAC  = 9;

  /** What IAC SB <xx> we are handling right now */
  private byte current_sb;

  /** IAC - init sequence for telnet negotiation. */
  private final static byte IAC  = (byte)255;
  /** [IAC] End Of Record */
  private final static byte EOR  = (byte)239;
  /** [IAC] WILL */
  private final static byte WILL  = (byte)251;
  /** [IAC] WONT */
  private final static byte WONT  = (byte)252;
  /** [IAC] DO */
  private final static byte DO    = (byte)253;
  /** [IAC] DONT */
  private final static byte DONT  = (byte)254;
  /** [IAC] Sub Begin */
  private final static byte SB  = (byte)250;
  /** [IAC] Sub End */
  private final static byte SE  = (byte)240;
  /** Telnet option: binary mode */
  private final static byte TELOPT_BINARY= (byte)0;  /* binary mode */
  /** Telnet option: echo text */
  private final static byte TELOPT_ECHO  = (byte)1;  /* echo on/off */
  /** Telnet option: sga */
  private final static byte TELOPT_SGA   = (byte)3;  /* supress go ahead */
  /** Telnet option: End Of Record */
  private final static byte TELOPT_EOR   = (byte)25;  /* end of record */
  /** Telnet option: Negotiate About Window Size */
  private final static byte TELOPT_NAWS  = (byte)31;  /* NA-WindowSize*/
  /** Telnet option: Terminal Type */
  private final static byte TELOPT_TTYPE  = (byte)24;  /* terminal type */

  private final static byte[] IACWILL  = { IAC, WILL };
  private final static byte[] IACWONT  = { IAC, WONT };
  private final static byte[] IACDO    = { IAC, DO      };
  private final static byte[] IACDONT  = { IAC, DONT };
  private final static byte[] IACSB  = { IAC, SB };
  private final static byte[] IACSE  = { IAC, SE };

  /** Telnet option qualifier 'IS' */
  private final static byte TELQUAL_IS = (byte)0;
  /** Telnet option qualifier 'SEND' */
  private final static byte TELQUAL_SEND = (byte)1;

  /** What IAC DO(NT) request do we have received already ? */
  private byte[] receivedDX;
  /** What IAC WILL/WONT request do we have received already ? */
  private byte[] receivedWX;
  /** What IAC DO/DONT request do we have sent already ? */
  private byte[] sentDX;
  /** What IAC WILL/WONT request do we have sent already ? */
  private byte[] sentWX;

  /**
   * Send a Telnet Escape character (IAC <code>)
   */
  public void sendTelnetControl(byte code)
    throws IOException {
    byte[] b = new byte[2];

    b[0] = IAC;
    b[1] = code;
    write(b);
  }


  /**
   * Handle an incoming IAC SB &lt;type&gt; &lt;bytes&gt; IAC SE
   * @param type type of SB
   * @param sbata byte array as &lt;bytes&gt;
   * @param sbcount nr of bytes. may be 0 too.
   */
  private void handle_sb(byte type, byte[] sbdata, int sbcount) 
    throws IOException {
    if(debug > 1) 
      System.err.println("TelnetIO.handle_sb("+type+")");
    switch (type) {
    case TELOPT_TTYPE:
      if (sbcount>0 && sbdata[0]==TELQUAL_SEND) {
        write(IACSB);write(TELOPT_TTYPE);write(TELQUAL_IS);
        /* FIXME: need more logic here if we use 
         * more than one terminal type
         */
        String ttype = getTerminalType();
        if(ttype == null) ttype = "dumb";
        write(ttype.getBytes());
        write(IACSE);
      }

    }
  }

  /**
   * Do not send any notifications at startup. We do not know,
   * whether the remote client understands telnet protocol handling,
   * so we are silent.
   * (This used to send IAC WILL SGA, but this is false for a compliant
   *  client.)
   */
  public void startup() throws IOException {
  }
  /**
   * Transpose special telnet codes like 0xff or newlines to values
   * that are compliant to the protocol. This method will also send
   * the buffer immediately after transposing the data.
   * @param buf the data buffer to be sent
   */
  public void transpose(byte[] buf) throws IOException {
    int i;
    
    byte[] nbuf,xbuf;
    int nbufptr=0;
    nbuf = new byte[buf.length*2]; // FIXME: buffer overflows possible

    for (i = 0; i < buf.length ; i++) {
      switch (buf[i]) {
      // Escape IAC twice in stream ... to be telnet protocol compliant
      // this is there in binary and non-binary mode.
      case IAC:
	nbuf[nbufptr++]=IAC;
	nbuf[nbufptr++]=IAC;
	break;
      // We need to heed RFC 854. LF (\n) is 10, CR (\r) is 13
      // we assume that the Terminal sends \n for lf+cr and \r for just cr
      // linefeed+carriage return is CR LF */ 
      case 10:	// \n
        if (receivedDX[TELOPT_BINARY + 128 ] != DO) {
	    while (nbuf.length - nbufptr < crlf.length) {
		    xbuf = new byte[nbuf.length*2];
		    System.arraycopy(nbuf,0,xbuf,0,nbufptr);
		    nbuf = xbuf;
	    }
	    for (int j=0;j<crlf.length;j++)
		nbuf[nbufptr++]=crlf[j];
	    break;
	} else {
	    // copy verbatim in binary mode.
	    nbuf[nbufptr++]=buf[i];
	}
	break;
      // carriage return is CR NUL */ 
      case 13:	// \r
        if (receivedDX[TELOPT_BINARY + 128 ] != DO) {
	    while (nbuf.length - nbufptr < cr.length) {
		    xbuf = new byte[nbuf.length*2];
		    System.arraycopy(nbuf,0,xbuf,0,nbufptr);
		    nbuf = xbuf;
	    }
	    for (int j=0;j<cr.length;j++)
		nbuf[nbufptr++]=cr[j];
	} else {
	    // copy verbatim in binary mode.
	    nbuf[nbufptr++]=buf[i];
	}
	break;
      // all other characters are just copied
      default:
	nbuf[nbufptr++]=buf[i];
	break;
      }
    }
    xbuf = new byte[nbufptr];
    System.arraycopy(nbuf,0,xbuf,0,nbufptr);
    write(xbuf);
  }

  public void setCRLF(String xcrlf) { crlf = xcrlf.getBytes(); }
  public void setCR(String xcr) { cr = xcr.getBytes(); }

  /**
   * Handle telnet protocol negotiation. The buffer will be parsed
   * and necessary actions are taken according to the telnet protocol.
   * See <A HREF="RFC-Telnet-URL">RFC-Telnet</A>
   * @param nbuf the byte buffer put out after negotiation
   * @return number of bytes processed, 0 for none, and -1 for end of buffer.
   */