/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
/**
 * This program will demonstrate SSH through jump hosts.
 * Suppose that you don't have direct accesses to host2 and host3.
 *   $ CLASSPATH=.:../build javac JumpHosts.java
 *   $ CLASSPATH=.:../build java JumpHosts usr1@host1 usr2@host2 usr3@host3
 * You will be asked passwords for those destinations,
 * and if everything works fine, you will get file lists of your home-directory
 * at host3.
 *
 */
import com.jcraft.jsch.*;
import java.awt.*;
import javax.swing.*;

public class JumpHosts {
  public static void main(String[] arg){

    try{
      JSch jsch = new JSch();

      if(arg.length <= 1){
        System.out.println("This program expects more arguments.");
        System.exit(-1);
      }

      Session session = null;
      Session[] sessions = new Session[arg.length];

      String host = arg[0];
      String user = host.substring(0, host.indexOf('@'));
      host = host.substring(host.indexOf('@')+1);

      sessions[0] = session = jsch.getSession(user, host, 22);
      session.setUserInfo(new MyUserInfo());
      session.connect();
      System.out.println("The session has been established to "+user+"@"+host);

      for(int i = 1; i < arg.length; i++){
        host = arg[i];
        user = host.substring(0, host.indexOf('@'));
        host = host.substring(host.indexOf('@')+1);

        int assinged_port = session.setPortForwardingL(0, host, 22);
        System.out.println("portforwarding: "+
                           "localhost:"+assinged_port+" -> "+host+":"+22);
        sessions[i] = session =
          jsch.getSession(user, "127.0.0.1", assinged_port);

        session.setUserInfo(new MyUserInfo());
        session.setHostKeyAlias(host);
        session.connect();
        System.out.println("The session has been established to "+
                           user+"@"+host);
      }

      ChannelSftp sftp = (ChannelSftp)session.openChannel("sftp");

      sftp.connect();
      sftp.ls(".",
              new ChannelSftp.LsEntrySelector() {
                public int select(ChannelSftp.LsEntry le) {
                  System.out.println(le);
                  return ChannelSftp.LsEntrySelector.CONTINUE;
                }
              });
      sftp.disconnect();

      for(int i = sessions.length-1; i >= 0; i--){
        sessions[i].disconnect();
      }
    }
    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
      }
    }
  }
}