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/*
 * Copyright (C) 2006-2010 Alfresco Software Limited.
 *
 * This file is part of Alfresco
 *
 * Alfresco is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Alfresco 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Alfresco. If not, see .
 */

package org.filesys.netbios;

import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * The network settings class contains various Windows Networking settings that are
 * needed by the NetBIOS and SMB layers.
 *
 * @author gkspencer
 */
public class NetworkSettings {

    // 	Broadcast mask for broadcast messages
    private static String m_broadcastMask;

    // 	Domain name/workgroup that this node is part of
    private static String m_domain;

    // 	Subnet mask address
    private static InetAddress m_subnetAddr;

    /**
     * Determine the boradcast mask from the local hosts TCP/IP address
     *
     * @param addr TCP/IP address to set the broadcast mask for, in 'nnn.nnn.nnn.nnn'
     *             format.
     * @return String
     * @exception UnknownHostException If the name cannot be converted using a DNS lookup
     */
    public static String GenerateBroadcastMask(String addr)
            throws UnknownHostException {

        //  Check if the broadcast mask has already been set
        if (m_broadcastMask != null)
            return m_broadcastMask;

        //  Set the TCP/IP address string
        String localIP = addr;

        if (localIP == null)
            localIP = InetAddress.getLocalHost().getHostAddress();

        //  Find the location of the first dot in the TCP/IP address
        int dotPos = localIP.indexOf('.');
        if (dotPos != -1) {

            //  Extract the leading IP address value
            String ipStr = localIP.substring(0, dotPos);
            int ipVal = Integer.valueOf(ipStr).intValue();

            //  Determine the broadcast mask to use
            if (ipVal <= 127) {

                //  Class A address
                m_broadcastMask = "" + ipVal + ".255.255.255";
            } else if (ipVal <= 191) {

                //  Class B adddress
                dotPos++;
                while (localIP.charAt(dotPos) != '.' && dotPos < localIP.length())
                    dotPos++;

                if (dotPos < localIP.length())
                    m_broadcastMask = localIP.substring(0, dotPos) + ".255.255";
            } else if (ipVal <= 223) {

                //  Class C address
                dotPos++;
                int dotCnt = 1;

                while (dotCnt < 3 && dotPos < localIP.length()) {

                    //  Check if the current character is a dot
                    if (localIP.charAt(dotPos++) == '.')
                        dotCnt++;
                }

                if (dotPos < localIP.length())
                    m_broadcastMask = localIP.substring(0, dotPos - 1) + ".255";
            }
        }

        //  Check if the broadcast mask has been set, if not then use a general
        //  broadcast mask
        if (m_broadcastMask == null) {

            //  Invalid TCP/IP address string format, use a general broadcast mask
            //  for now.
            m_broadcastMask = "255.255.255.255";
        }

        //  Return the broadcast mask string
        return m_broadcastMask;
    }

    /**
     * Return the broadcast mask as an address.
     *
     * @return InetAddress
     * @exception UnknownHostException If the name cannot be converted using a DNS lookup
     */
    public final static InetAddress getBroadcastAddress()
            throws UnknownHostException {

        //  Check if the subnet address is valid
        if (m_subnetAddr == null) {

            //  Generate the subnet mask
            String subnet = GenerateBroadcastMask(null);
            m_subnetAddr = InetAddress.getByName(subnet);
        }

        //  Return the subnet mask address
        return m_subnetAddr;
    }

    /**
     * Get the broadcast mask.
     *
     * @return String
     */
    public static String getBroadcastMask() {
        return m_broadcastMask;
    }

    /**
     * Get the local domain/workgroup name.
     *
     * @return String
     */
    public static String getDomain() {
        return m_domain;
    }

    /**
     * Determine if the broadcast mask has been setup.
     *
     * @return boolean
     */
    public static boolean hasBroadcastMask() {
        if (m_broadcastMask == null)
            return false;
        return true;
    }

    /**
     * Set the broadcast mask to be used for broadcast packets.
     *
     * @param mask String
     */
    public static void setBroadcastMask(String mask) {
        m_broadcastMask = mask;
    }

    /**
     * Set the local domain/workgroup name.
     *
     * @param domain String
     */
    public static void setDomain(String domain) {
        m_domain = domain;
    }
}