telnetprotocolhandler.java

The Javatm Telnet Application/Applet 很好用的

  public int negotiate(byte nbuf[])
  throws IOException
  {
    byte sbbuf[] = new byte[tempbuf.length];
    int count = tempbuf.length;
    byte[] buf = tempbuf;
    byte sendbuf[] = new byte[3];
    byte b,reply;
    int  sbcount = 0;
    int boffset = 0, noffset = 0;
    boolean dobreak = false;

    if (count == 0) 	// buffer is empty.
      return -1;

    while(!dobreak && (boffset < count) && (noffset < nbuf.length)) {
      b=buf[boffset++];
      // of course, byte is a signed entity (-128 -> 127)
      // but apparently the SGI Netscape 3.0 doesn't seem
      // to care and provides happily values up to 255
      if (b>=128)
        b=(byte)((int)b-256);
      if(debug > 2) {
        Byte B = new Byte(b);
        System.err.print("byte: " + B.intValue()+ " ");
      }
      switch (neg_state) {
      case STATE_DATA:
        if (b==IAC) {
          neg_state = STATE_IAC;
	  dobreak = true; // leave the loop so we can sync.
        } else 
          nbuf[noffset++]=b;
        break;
      case STATE_IAC:
        switch (b) {
        case IAC:
          if(debug > 2) System.err.print("IAC ");
          neg_state = STATE_DATA;
          nbuf[noffset++]=IAC;
          break;
        case WILL:
          if(debug > 2) System.err.print("WILL ");
          neg_state = STATE_IACWILL;
          break;
        case WONT:
          if(debug > 2) System.err.print("WONT ");
          neg_state = STATE_IACWONT;
          break;
        case DONT:
          if(debug > 2) System.err.print("DONT ");
          neg_state = STATE_IACDONT;
          break;
        case DO:
          if(debug > 2) System.err.print("DO ");
          neg_state = STATE_IACDO;
          break;
        case EOR:
          if(debug > 1) System.err.print("EOR ");
  	  notifyEndOfRecord();
	  dobreak = true; // leave the loop so we can sync.
          neg_state = STATE_DATA;
          break;
        case SB:
          if(debug > 2) System.err.print("SB ");
          neg_state = STATE_IACSB;
          sbcount = 0;
          break;
        default:
          if(debug > 2) System.err.print("<UNKNOWN "+b+" > ");
          neg_state = STATE_DATA;
          break;
        }
        break;
      case STATE_IACWILL:
        switch(b) {
        case TELOPT_ECHO:
          if(debug > 2) System.err.println("ECHO");
          reply = DO;
          setLocalEcho(false);
          break;
        case TELOPT_SGA:
          if(debug > 2) System.err.println("SGA");
          reply = DO;
          break;
        case TELOPT_EOR:
          if(debug > 2) System.err.println("EOR");
          reply = DO;
          break;
        case TELOPT_BINARY:
          if(debug > 2) System.err.println("BINARY");
          reply = DO;
          break;
        default:
          if(debug > 2) System.err.println("<UNKNOWN,"+b+">");
          reply = DONT;
          break;
        }
        if(debug > 1) System.err.println("<"+b+", WILL ="+WILL+">");
        if (reply != sentDX[b+128] || WILL != receivedWX[b+128]) {
          sendbuf[0]=IAC;
          sendbuf[1]=reply;
          sendbuf[2]=b;
          write(sendbuf);
          sentDX[b+128] = reply;
          receivedWX[b+128] = WILL;
        }
        neg_state = STATE_DATA;
        break;
      case STATE_IACWONT:
        switch(b) {
        case TELOPT_ECHO:
          if(debug > 2) System.err.println("ECHO");
          setLocalEcho(true);
          reply = DONT;
          break;
        case TELOPT_SGA:
          if(debug > 2) System.err.println("SGA");
          reply = DONT;
          break;
        case TELOPT_EOR:
          if(debug > 2) System.err.println("EOR");
          reply = DONT;
          break;
        case TELOPT_BINARY:
          if(debug > 2) System.err.println("BINARY");
          reply = DONT;
          break;
        default:
          if(debug > 2) System.err.println("<UNKNOWN,"+b+">");
          reply = DONT;
          break;
        }
        if(reply != sentDX[b+128] || WONT != receivedWX[b+128]) {
          sendbuf[0]=IAC;
          sendbuf[1]=reply;
          sendbuf[2]=b;
          write(sendbuf);
          sentDX[b+128] = reply;
          receivedWX[b+128] = WILL;
        }
        neg_state = STATE_DATA;
        break;
      case STATE_IACDO:
        switch (b) {
        case TELOPT_ECHO:
          if(debug > 2) System.err.println("ECHO");
          reply = WILL;
          setLocalEcho(true);
          break;
        case TELOPT_SGA:
          if(debug > 2) System.err.println("SGA");
          reply = WILL;
          break;
        case TELOPT_TTYPE:
          if(debug > 2) System.err.println("TTYPE");
          reply = WILL;
          break;
        case TELOPT_BINARY:
          if(debug > 2) System.err.println("BINARY");
          reply = WILL;
          break;
        case TELOPT_NAWS:
          if(debug > 2) System.err.println("NAWS");
          Dimension size = getWindowSize();
          receivedDX[b] = DO;
          if(size == null) {
            // this shouldn't happen
            write(IAC);
            write(WONT);
            write(TELOPT_NAWS);
            reply = WONT;
            sentWX[b] = WONT;
            break;
          }
          reply = WILL;
          sentWX[b] = WILL;
          sendbuf[0]=IAC;
          sendbuf[1]=WILL;
          sendbuf[2]=TELOPT_NAWS;
          write(sendbuf);
          write(IAC);write(SB);write(TELOPT_NAWS);
          write((byte) (size.width >> 8));
          write((byte) (size.width & 0xff));
          write((byte) (size.height >> 8));
          write((byte) (size.height & 0xff));
          write(IAC);write(SE);
          break;
        default:
          if(debug > 2) System.err.println("<UNKNOWN,"+b+">");
          reply = WONT;
          break;
        }
        if(reply != sentWX[128+b] || DO != receivedDX[128+b]) {
          sendbuf[0]=IAC;
          sendbuf[1]=reply;
          sendbuf[2]=b;
          write(sendbuf);
          sentWX[b+128] = reply;
          receivedDX[b+128] = DO;
        }
        neg_state = STATE_DATA;
        break;
      case STATE_IACDONT:
        switch (b) {
        case TELOPT_ECHO:
          if(debug > 2) System.err.println("ECHO");
          reply = WONT;
          setLocalEcho(false);
          break;
        case TELOPT_SGA:
          if(debug > 2) System.err.println("SGA");
          reply = WONT;
          break;
        case TELOPT_NAWS:
          if(debug > 2) System.err.println("NAWS");
          reply = WONT;
          break;
        case TELOPT_BINARY:
          if(debug > 2) System.err.println("BINARY");
          reply = WONT;
          break;
        default:
          if(debug > 2) System.err.println("<UNKNOWN,"+b+">");
          reply = WONT;
          break;
        }
        if(reply != sentWX[b+128] || DONT != receivedDX[b+128]) {
          write(IAC);write(reply);write(b);
          sentWX[b+128] = reply;
          receivedDX[b+128] = DONT;
        }
        neg_state = STATE_DATA;
        break;
      case STATE_IACSBIAC:
        if(debug > 2) System.err.println(""+b+" ");
        if (b == IAC) {
          sbcount = 0;
          current_sb = b;
          neg_state = STATE_IACSBDATA;
        } else {
          System.err.println("(bad) "+b+" ");
          neg_state = STATE_DATA;
        }
        break;
      case STATE_IACSB:
        if(debug > 2) System.err.println(""+b+" ");
        switch (b) {
        case IAC:
          neg_state = STATE_IACSBIAC;
          break;
        default:
          current_sb = b;
          sbcount = 0;
          neg_state = STATE_IACSBDATA;
          break;
        }
        break;
      case STATE_IACSBDATA:
        if (debug > 2) System.err.println(""+b+" ");
        switch (b) {
        case IAC:
          neg_state = STATE_IACSBDATAIAC;
          break;
        default:
          sbbuf[sbcount++] = b;
          break;
        }
        break;
      case STATE_IACSBDATAIAC:
        if (debug > 2) System.err.println(""+b+" ");
        switch (b) {
        case IAC:
          neg_state = STATE_IACSBDATA;
          sbbuf[sbcount++] = IAC;
          break;
        case SE:
          handle_sb(current_sb,sbbuf,sbcount);
          current_sb = 0;
          neg_state = STATE_DATA;
          break;
        case SB:
          handle_sb(current_sb,sbbuf,sbcount);
          neg_state = STATE_IACSB;
          break;
        default:
          neg_state = STATE_DATA;
          break;
        }
        break;
      default:
        if (debug > 1) 
          System.err.println("This should not happen: "+neg_state+" ");
        neg_state = STATE_DATA;
        break;
      }
    }
    // shrink tempbuf to new processed size.
    byte[] xb = new byte[count-boffset];
    System.arraycopy(tempbuf,boffset,xb,0,count-boffset);
    tempbuf = xb;
    return noffset;
  }

  public void inputfeed(byte[] b, int len) {
    byte[] xb = new byte[tempbuf.length+len];

    System.arraycopy(tempbuf,0,xb,0,tempbuf.length);
    System.arraycopy(b,0,xb,tempbuf.length,len);
    tempbuf = xb;
  }
}