import java.net.*;import java.util.*;/***Thread to scan individual hosts**Copyright (C) 2003 Tom Salmon tom@slashtom.org**This program is free software; you can redistribute it and/ormodify it under the terms of the GNU General Public Licenseas published by the Free Software Foundation; version 2.This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU 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 SoftwareFoundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.**@author Tom Salmon tom@slashtom.org*@version 0.3.1*/public class ScanHost extends Observable implements Observer, Runnable {	protected static int MAX_THREADS = 20;	// max threads to run per host on windows	protected static int WINDOWS_MAX_THREADS = 12; 	private String hostname;	private InetAddress victim;	private boolean tcp;	private boolean udp;	private int[] portsToScan;	private PortLookup portService;	private Status statusReg;	private int portsScanned = 0;	private int resultsPending = 0;	private boolean stopped = false;	/**	*Constructs thread to Scan an individual host, on set ports and protocol	*@param String victim - the host to scan	*@param boolean TCP/IP scanning enabed	*@param boolean UDP scanning enabled	*@param int[] the list of ports to be scanned	*@param PortLookup the service defining names for the ports	*/	public ScanHost(String hostname, 					boolean tcp, 					boolean udp, 					int[] portsToScan, 					PortLookup portService){		this.hostname = hostname;		this.tcp = tcp;		this.udp = udp;		this.portsToScan = portsToScan;		this.portService = portService;		statusReg = new Status(tcp, udp, hostname);		// if running Windows, set number of threads accordingly		if (System.getProperty("os.name").startsWith("Windows")){			this.MAX_THREADS = this.WINDOWS_MAX_THREADS;		}        try{            victim = InetAddress.getByName(hostname);        }        catch(UnknownHostException e){			victim = null;		}	}	public String getHostname(){		return this.hostname;	}	public void run(){		if (victim == null){			notifyObservers(statusReg);			setChanged();		}        int p;        for (int i=0; i<portsToScan.length; i++){            p = portsToScan[i];			if (resultsPending - portsScanned > this.MAX_THREADS){				// we currently have too many threads running				// wait until at least half of the threads have finished				while (resultsPending - portsScanned > (this.MAX_THREADS/2)){					try{						Thread.sleep(5000);					}					catch(Exception e){					}				}			}            //for updating the progress bar            setChanged();            if (i == portsToScan.length-1){                notifyObservers("       Waiting for responces       ");            }            else{                notifyObservers("Probing:  " + hostname + "   PORT: "                            + p + "    " + portService.getService(p, "tcp"));            }            if (stopped){                break;            }            if (tcp){                ScanTCP scan = new ScanTCP(victim, p);                scan.addObserver(this);                Thread scanThread = new Thread(scan);				//scanThread.setPriority(Thread.MAX_PRIORITY);                scanThread.start();				//increment the results that we are waiting for				resultsPending++;				// pause before starting new thread				try{					Thread.sleep(100);				}				catch(Exception e){				}            }            if (udp){                ScanUDP scan = new ScanUDP(victim, p);                scan.addObserver(this);                Thread scanThread = new Thread(scan);				//scanThread.setPriority(Thread.MAX_PRIORITY);                scanThread.start();				//increment the results that we are waiting for				resultsPending++;                try{                    Thread.sleep(1100); //pause before starting next thread                }                catch(Exception e){                    ;                }            }        }        while (!this.stopped && !statusReg.isUnreachable()          && portsScanned < resultsPending){            try{                Thread.sleep(500); //all results havent arrived yet            }            catch(Exception e){                ;            }        }        String returnString = new String();        try{            returnString =                 InetAddress.getByName(hostname).getHostName() + "(" +                 InetAddress.getByName(hostname).getHostAddress() + ")\n";        }        catch(UnknownHostException e){            returnString = hostname + "\n";        }        returnString += statusReg.toString();		setChanged();        notifyObservers(statusReg);    }    public void update(Observable o, Object arg){        portsScanned++;        if (o instanceof ScanTCP){            int port = ((ScanTCP)o).getPort();            if (arg == null){ //host is unreachable                statusReg.setUnreachable();            }            String result = (String)arg;            if (result.equals("CLOSED"))                statusReg.addStatus(port, Status.CLOSED, Status.TCP);            else if (result.equals("DROPPED"))                statusReg.addStatus(port, Status.DROPPED, Status.TCP);            else if (result.equals("OPEN"))                statusReg.addStatus(port, Status.OPEN, Status.TCP);        }        else if (o instanceof ScanUDP){            int port = ((ScanUDP)o).getPort();            String result = (String)arg;            if (result.equals("CLOSED"))                statusReg.addStatus(port, Status.CLOSED, Status.UDP);            else if (result.equals("OPEN"))                statusReg.addStatus(port, Status.OPEN, Status.UDP);        }    }    /**    *Stops the scanning of a host    */    public void stop(){        stopped = true;    }}