/*

 * Subnetting.java -- Java Applet/application

 * Copyright (C) 2000  Petteri Kettunen  

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU 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 Software Foundation, Inc., 

 * 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA

 *

 */

/*

 * $Revision: 1.2 $

 *

 * Comments? Suggestions? -> petterik@iki.fi

 */



import java.applet.Applet;

import java.awt.*;

import java.awt.event.*;

import java.io.*;

import java.lang.*;

import java.net.*;

import java.util.StringTokenizer;

import java.math.*;



public class Subnetting extends Applet     

    implements ItemListener, ActionListener {

    TextArea taResult;

    TextField tfIP;

    Choice chNWBits, chSNBits;

    Checkbox cbZeroSN;

    Button calcButton;

    int iNWBits = 0, iSNBits = 0, iDefaultNWBits = 24;

    boolean bDefaultZeroSN = false; // affects only Applet

    final static String sVersion = "0.9b";



    // applet inits    

    public void init() {	

	setBackground(Color.white);

	chNWBits = new Choice();

	chSNBits = new Choice();

	taResult = new TextArea("", 24, 80);

	taResult.setFont(new Font("Courier", Font.PLAIN, 12));

	taResult.setText(getSplashText());

	for (int i = 0; i <= 32; i++) {

	    chNWBits.addItem("" + i);

	    chSNBits.addItem("" + i);

	}

	if (iDefaultNWBits > 0 && iDefaultNWBits <= 32) {

	    chNWBits.select(iNWBits = iDefaultNWBits);

	}

	//setLayout(new GridLayout(4));

	add(tfIP = new TextField("127.0.0.1", 18));

	add(new Label("NW Bits"));

	add(chNWBits);

	chNWBits.addItemListener(this);

	add(new Label("SN Bits"));

	add(chSNBits);

	chSNBits.addItemListener(this);

	add(cbZeroSN = new Checkbox("zero subnet", bDefaultZeroSN));

	add(calcButton = new Button("Calculate"));

	calcButton.addActionListener(this);

	add("South", taResult);

    }



    public String getAppletInfo() {

	String info = "Subnetting.java " + sVersion +

	    "\nby Petteri Kettunen <petterik@iki.fi>";

	return info;

    }

    

    /* TODO... public String[][] getParameterInfo() {

       String[][] info = {

	{"IMAGE_DIR", "string", "Image directory relative to Applet."},

	};

        return info;

	} */



    public void start() {

	//panel.start();

    }



    public void stop() {

	//panel.stop();

    }



    public void destroy() {

        //remove(panel);

        //remove(controls);

    }



    private static String getSplashText() {

	return "'Subnetting.java' version " + sVersion + " Copyright (C) 2000 Petteri Kettunen.\n\n'Subnetting.java' comes with ABSOLUTELY NO WARRANTY. This is free software,\nand you are welcome to redistribute it under certain conditions; see the\nsource code or URL http://www.iki.fi/petterik/ for details.\n\n";

    }



    // octet to 'bit' string 

    private static String o2b(int iOctet) {

	String res = "";

	int val = iOctet;



	for (int t = 128; t > 0; t /=2) {

	    if (val >= t) {

		res = res.concat("1");

		val -= t;

	    } else {

		res = res.concat("0");

	    }

	}

	return res;

    }

    

    // convert four bits to hex string

    private static String b2h(String sBits) {

	String res;

	int val = b2o(sBits);



	switch(val) {

	case 15: res = "f"; break;

	case 14: res = "e"; break;

	case 13: res = "d"; break;

	case 12: res = "c"; break;

	case 11: res = "b"; break;

	case 10: res = "a"; break;

	default: res = "" + val;

	}

	return res;

    }



    // 'bit' string to octet 

    private static int b2o(String sBits) {	

	if (sBits.length() == 4) {

	    return Integer.valueOf(sBits.substring(0, 1)).intValue() * 8 +

		Integer.valueOf(sBits.substring(1, 2)).intValue() * 4 +

		Integer.valueOf(sBits.substring(2, 3)).intValue() * 2 +

		Integer.valueOf(sBits.substring(3, 4)).intValue();	

	}

	return Integer.valueOf(sBits.substring(0,1)).intValue() * 128 +

	    Integer.valueOf(sBits.substring(1, 2)).intValue() * 64 +

	    Integer.valueOf(sBits.substring(2, 3)).intValue() * 32 +

	    Integer.valueOf(sBits.substring(3, 4)).intValue() * 16 +

	    Integer.valueOf(sBits.substring(4, 5)).intValue() * 8 +

	    Integer.valueOf(sBits.substring(5, 6)).intValue() * 4 +

	    Integer.valueOf(sBits.substring(6, 7)).intValue() * 2 +

	    Integer.valueOf(sBits.substring(7)).intValue();

    }



    // subnet mask: network and subnet bits 1, host bits 0

    private static String getNetmaskStr(int iNW, int iSN) {

	String res = "";

	int n = iNW + iSN, i = 0;

	

	while (i++ < n) {

	    res = res.concat("1");

	}

	while (i++ <= 32) {

	    res = res.concat("0");

	}

	return res;

    }



    // mask IP with network mask

    private static String getNetwork(String sIPBits, String sNWMaskBits) {

	String res = "";

	int i = 0;

	

	while (i < 32) {

	    if (sNWMaskBits.substring(i, i+1).equals("1")) {

		res = res.concat(sIPBits.substring(i, i+1));

	    } else {

		res = res.concat("0");

	    }

	    i++;

	}

	return res;

    }



    // subnet address: all host bits are 0

    private static String getSN(String sNWBits, String sSNBits) {

	String res = sNWBits + sSNBits;	



	while (res.length() < 32) {

	    res = res.concat("0");

	}

	return res;

    }



    // broadcast address: all host bits are 1

    private static String getBcast(String sNWBits, String sSNBits) {

	String res = sNWBits + sSNBits;	



	while (res.length() < 32) {

	    res = res.concat("1");

	}

	return res;

    }



    // first host: subnet address + 1

    private static String getFirstHost(String sSN) {

	return sSN.substring(0,24) + o2b(b2o(sSN.substring(24)) + 1);

    }



    // last host: broadcast - 1

    private static String getLastHost(String sBcast) {

	return sBcast.substring(0,24) + o2b(b2o(sBcast.substring(24)) - 1);

    }



    // make IP to human-readable format

    private static String decodeIP(String bits) {

	String [] octets = new String[4];

	String [] hex = new String[8];



	octets[0] = bits.substring(0,8);

	hex[0] = b2h(octets[0].substring(0,4));

	hex[1] = b2h(octets[0].substring(4));

	octets[1] = bits.substring(8,16);

	hex[2] = b2h(octets[1].substring(0,4));

	hex[3] = b2h(octets[1].substring(4));

	octets[2] = bits.substring(16,24);

	hex[4] = b2h(octets[2].substring(0,4));

	hex[5] = b2h(octets[2].substring(4));

	octets[3] = bits.substring(24,32);

	hex[6] = b2h(octets[3].substring(0,4));

	hex[7] = b2h(octets[3].substring(4));

	return octets[0] + "." + octets[1] + "." + octets[2] + "." +

	    octets[3] + " " + 

	    hex[0] + hex[1] + hex[2] + hex[3] + hex[4] + hex[5] +

	    hex[6] + hex[7] + " " 

	    + b2o(octets[0]) + "." + b2o(octets[1]) + 

	    "." + b2o(octets[2]) + "." + b2o(octets[3]);

    }



    // the main calculator function

    private static String calcSubnetting(String sIP, int iNW, int iSN, boolean bZeroSN) {

	int i, nSubnets;

	String res = "";

	String [] octet = new String[4];

	StringTokenizer st;

	int [] iOctet = new int[4];



	// catch some pathological cases...

	if (iNW < 0) {

	    return "ERROR: negative number of network bits\n";

	}

	if (iSN < 0) {

	    return "ERROR: negative number of subnet bits\n";

	}

	if (iNW == 0) {

	    return "ERROR: network bits equals to zero - no network?\n";

	}

	if ((iNW + iSN) > 32) {

	    return "ERROR: the sum of network and subnet bits is over 32\n";

	}

	// get the IP

	try {

	    st = new StringTokenizer(sIP, ".");

	    for (i = 0; i != 4; i++) {

		octet[i] = st.nextToken();	    

		iOctet[i] = Integer.valueOf(octet[i]).intValue();

	    }

	} catch (Exception e) {

	    return "ERROR: Invalid IP address string '" + sIP + "'\n";

	}

	// extract and check the values of octets

	for (i = 0; i != 4; i++) {

	    if (iOctet[i] < 0 || iOctet[i] > 255) {

		return "Invalid IP address '" + sIP + 

		    "' -- all octets should be in range 0-255\n";

	    }

	}

	String nmStr = getNetmaskStr(iNW, iSN);

	String nwMaskStr = getNetmaskStr(iNW, 0);

	String ipBits = o2b(iOctet[0]) +  o2b(iOctet[1]) + o2b(iOctet[2]) +

	    o2b(iOctet[3]);

	String nwStr = getNetwork(ipBits, nwMaskStr);

	int nSubs = (int)Math.pow(2, iSN);

	if (iSN == 0) {

	    // subnet calculation will not take place

	    nSubnets = 0;

	} else {

	    if (bZeroSN) {

		i = 0;

		nSubnets = nSubs;

	    } else {

		nSubs -= 1;

		i = 1;

		nSubnets = nSubs - 1;

	    }

	}

	res = res.concat("\nnetwork bits " + iNW + 

			 ", subnet bits " + iSN + 

			 ", zero subnet " + (bZeroSN ? "on" : "off") +

			 ", total subnets " + nSubnets + "\n\n");

	res = res.concat("network        " + decodeIP(nwStr) + "\n");

	res = res.concat("network mask   " + decodeIP(nwMaskStr) + "\n");

	//res = res.concat("IP address    " + decodeIP(ipBits) + "\n");

	res = res.concat("netmask        " + decodeIP(nmStr) + "\n\n");

	String stub = nwStr.substring(0, iNW);

	// catch this here so the applet can be used for checking netmask

	if (iSN == 0) {

	    res = res.concat("WARNING: subnet bits equals to zero - no subnetting?\n");

	    return res;

	}

	if (bZeroSN == false && iSN == 1) {

	    res = res.concat("ERROR: one subnet bit while zero subnet not allowed\n");

	    return res;

	}

	while (i < nSubs) {

	    String sSubnetPart = o2b(i).substring(8 - iSN);

	    String snAddress = getSN(stub, sSubnetPart);

	    String sFirstHost = getFirstHost(snAddress);

	    String bcAddress = getBcast(stub, sSubnetPart);

	    String sLastHost = getLastHost(bcAddress);

	    res = res.concat("  subnet  " + i + ":\n");

	    res = res.concat("    network    " + decodeIP(snAddress) + "\n");

	    res = res.concat("    first host " + decodeIP(sFirstHost) + "\n");

	    res = res.concat("    last host  " + decodeIP(sLastHost) + "\n");

	    res = res.concat("    broadcast  " + decodeIP(bcAddress) + "\n");

	    i++;

	}

	return res;

    }



    // check for choice events

    public void itemStateChanged(ItemEvent e) {

	if (e.getSource() == chNWBits) {

	    iNWBits = Integer.valueOf(chNWBits.getSelectedItem()).intValue();

	} else if (e.getSource() == chSNBits) {

	    iSNBits = Integer.valueOf(chSNBits.getSelectedItem()).intValue();

	}

    }



    // check for valid button events

    public void actionPerformed(ActionEvent ev) {

	String buttonLabel = ev.getActionCommand();



	if (buttonLabel.equals("Calculate")) {

	    taResult.setText(calcSubnetting(tfIP.getText().trim(), 

					      iNWBits, iSNBits, 

					      cbZeroSN.getState()));

	}

    }



    // entry point of the program when run as application

    public static void main(String[] args) {	

	if (args.length != 4) {

	    System.out.println("usage: java Subnetting <ip address> <network bits> <subnet bits> <subnet zero flag>");

	    System.exit(1);

	}

	String sIP = args[0];

	int iNW = Integer.valueOf(args[1]).intValue();

	int iSN = Integer.valueOf(args[2]).intValue();

	int snflag = Integer.valueOf(args[3]).intValue();

	System.out.print(getSplashText());

	System.out.print(calcSubnetting(sIP, iNW, iSN, (snflag != 0)));

    }

}











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