StreamForwarding.java

/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
import com.jcraft.jsch.*;
import java.awt.*;
import javax.swing.*;
import java.net.*;

public class StreamForwarding{
  public static void main(String[] arg){
    int port;

    try{

      ServerSocket ss = new ServerSocket(8888);    //
      Socket s = ss.accept();                      //

      JSch jsch=new JSch();

      String host=null;
      if(arg.length>0){
        host=arg[0];
      }
      else{
        host=JOptionPane.showInputDialog("Enter username@hostname",
                                         System.getProperty("user.name")+
                                         "@localhost"); 
      }
      String user=host.substring(0, host.indexOf('@'));
      host=host.substring(host.indexOf('@')+1);

      Session session=jsch.getSession(user, host, 22);

      // username and password will be given via UserInfo interface.
      UserInfo ui=new MyUserInfo();
      session.setUserInfo(ui);
      session.connect();

      String foo=JOptionPane.showInputDialog("Enter host and port", 
						 "host:port");
      host=foo.substring(0, foo.indexOf(':'));
      port=Integer.parseInt(foo.substring(foo.indexOf(':')+1));

      System.out.println("System.{in,out} will be forwarded to "+
			 host+":"+port+".");
      Channel channel=session.openChannel("direct-tcpip");
      // ((ChannelDirectTCPIP)channel).setInputStream(System.in);
      // ((ChannelDirectTCPIP)channel).setOutputStream(System.out);
      ((ChannelDirectTCPIP)channel).setInputStream(s.getInputStream());    //
      ((ChannelDirectTCPIP)channel).setOutputStream(s.getOutputStream());  //
      ((ChannelDirectTCPIP)channel).setHost(host);
      ((ChannelDirectTCPIP)channel).setPort(port);
      channel.connect();
    }
    catch(Exception e){
      System.out.println(e);
    }
  }

  public static class MyUserInfo implements UserInfo, UIKeyboardInteractive{
    public String getPassword(){ return passwd; }
    public boolean promptYesNo(String str){
      Object[] options={ "yes", "no" };
      int foo=JOptionPane.showOptionDialog(null, 
             str,
             "Warning", 
             JOptionPane.DEFAULT_OPTION, 
             JOptionPane.WARNING_MESSAGE,
             null, options, options[0]);
       return foo==0;
    }
  
    String passwd;
    JTextField passwordField=(JTextField)new JPasswordField(20);

    public String getPassphrase(){ return null; }
    public boolean promptPassphrase(String message){ return true; }
    public boolean promptPassword(String message){
      Object[] ob={passwordField}; 
      int result=
	  JOptionPane.showConfirmDialog(null, ob, message,
					JOptionPane.OK_CANCEL_OPTION);
      if(result==JOptionPane.OK_OPTION){
	passwd=passwordField.getText();
	return true;
      }
      else{ return false; }
    }
    public void showMessage(String message){
      JOptionPane.showMessageDialog(null, message);
    }
    final GridBagConstraints gbc = 
      new GridBagConstraints(0,0,1,1,1,1,
                             GridBagConstraints.NORTHWEST,
                             GridBagConstraints.NONE,
                             new Insets(0,0,0,0),0,0);
    private Container panel;
    public String[] promptKeyboardInteractive(String destination,
                                              String name,
                                              String instruction,
                                              String[] prompt,
                                              boolean[] echo){
      panel = new JPanel();
      panel.setLayout(new GridBagLayout());

      gbc.weightx = 1.0;
      gbc.gridwidth = GridBagConstraints.REMAINDER;
      gbc.gridx = 0;
      panel.add(new JLabel(instruction), gbc);
      gbc.gridy++;

      gbc.gridwidth = GridBagConstraints.RELATIVE;

      JTextField[] texts=new JTextField[prompt.length];
      for(int i=0; i<prompt.length; i++){
        gbc.fill = GridBagConstraints.NONE;
        gbc.gridx = 0;
        gbc.weightx = 1;
        panel.add(new JLabel(prompt[i]),gbc);

        gbc.gridx = 1;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.weighty = 1;
        if(echo[i]){
          texts[i]=new JTextField(20);
        }
        else{
          texts[i]=new JPasswordField(20);
        }
        panel.add(texts[i], gbc);
        gbc.gridy++;
      }

      if(JOptionPane.showConfirmDialog(null, panel, 
                                       destination+": "+name,
                                       JOptionPane.OK_CANCEL_OPTION,
                                       JOptionPane.QUESTION_MESSAGE)
         ==JOptionPane.OK_OPTION){
        String[] response=new String[prompt.length];
        for(int i=0; i<prompt.length; i++){
          response[i]=texts[i].getText();
        }
	return response;
      }
      else{
        return null;  // cancel
      }
    }
  }
}