SSHManager.java

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package edu.rice.cs.hpc.remote.tunnel;


import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.jcraft.jsch.Channel;
import com.jcraft.jsch.ChannelExec;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;

/*****************************************************************
 * 
 * wrapper class for JSCH library
 *
 *****************************************************************/
public class SSHManager 
{
    private static final Logger LOGGER = 
            Logger.getLogger(SSHManager.class.getName());
    private JSch jschSSHChannel;
    private String strUserName;
    private String strConnectionIP;
    private int intConnectionPort;
    private String strPassword;
    private Session sesConnection;
    private int intTimeOut;

    private void doCommonConstructorActions(String userName, 
            String password, String connectionIP, String knownHostsFileName)
    {
        jschSSHChannel = new JSch();

        try
        {
            jschSSHChannel.setKnownHosts(knownHostsFileName);
        }
        catch(JSchException jschX)
        {
            logError(jschX.getMessage());
        }

        strUserName = userName;
        strPassword = password;
        strConnectionIP = connectionIP;
    }

    public SSHManager(String userName, String password, 
            String connectionIP, String knownHostsFileName)
    {
        doCommonConstructorActions(userName, password, 
                connectionIP, knownHostsFileName);
        intConnectionPort = 22;
        intTimeOut = 60000;
    }

    public SSHManager(String userName, String password, String connectionIP, 
            String knownHostsFileName, int connectionPort)
    {
        doCommonConstructorActions(userName, password, connectionIP, 
                knownHostsFileName);
        intConnectionPort = connectionPort;
        intTimeOut = 60000;
    }

    public SSHManager(String userName, String password, String connectionIP, 
            String knownHostsFileName, int connectionPort, int timeOutMilliseconds)
    {
        doCommonConstructorActions(userName, password, connectionIP, 
                knownHostsFileName);
        intConnectionPort = connectionPort;
        intTimeOut = timeOutMilliseconds;
    }

    public String connect()
    {
        String errorMessage = null;

        try
        {
            sesConnection = jschSSHChannel.getSession(strUserName, 
                    strConnectionIP, intConnectionPort);
            sesConnection.setPassword(strPassword);
            // UNCOMMENT THIS FOR TESTING PURPOSES, BUT DO NOT USE IN PRODUCTION
            // sesConnection.setConfig("StrictHostKeyChecking", "no");
            sesConnection.connect(intTimeOut);
        }
        catch(JSchException jschX)
        {
            errorMessage = jschX.getMessage();
        }

        return errorMessage;
    }

    private String logError(String errorMessage)
    {
        if(errorMessage != null)
        {
            LOGGER.log(Level.SEVERE, "{0}:{1} - {2}", 
                    new Object[]{strConnectionIP, intConnectionPort, errorMessage});
        }

        return errorMessage;
    }

    private String logWarning(String warnMessage)
    {
        if(warnMessage != null)
        {
            LOGGER.log(Level.WARNING, "{0}:{1} - {2}", 
                    new Object[]{strConnectionIP, intConnectionPort, warnMessage});
        }

        return warnMessage;
    }

    public String sendCommand(String command)
    {
        StringBuilder outputBuffer = new StringBuilder();

        try
        {
            Channel channel = sesConnection.openChannel("exec");
            ((ChannelExec)channel).setCommand(command);
            channel.connect();
            InputStream commandOutput = channel.getInputStream();
            int readByte = commandOutput.read();

            while(readByte != 0xffffffff)
            {
                outputBuffer.append((char)readByte);
                readByte = commandOutput.read();
            }

            channel.disconnect();
        }
        catch(IOException ioX)
        {
            logWarning(ioX.getMessage());
            return null;
        }
        catch(JSchException jschX)
        {
            logWarning(jschX.getMessage());
            return null;
        }

        return outputBuffer.toString();
    }

    public void close()
    {
        sesConnection.disconnect();
    }


    static public void main(String []args)
    {
        if (args.length != 4) {
            System.out.println("Syntax: java SSHManager username password hostname command");
            return;
        }

        String command = args[3];
        String userName = args[0];
        String password = args[1];
        String connectionIP = args[2];

        System.out.println("sendCommand for: " + userName + "@" + connectionIP + "\npassword: " + password +"\nCommand: " + command);

        SSHManager instance = new SSHManager(userName, password, connectionIP, "");
        String errorMessage = instance.connect();

        if(errorMessage != null)
        {
            System.out.println(errorMessage);
        }

        // call sendCommand for each command and the output 
        //(without prompts) is returned
        String result = instance.sendCommand(command);
        // close only after all commands are sent
        instance.close();
        assert(result != null && result.length()>0);
    }

}