/*
 * $Header: /cvsroot/mvnforum/myvietnam/src/net/myvietnam/mvncore/filter/IPFilter.java,v 1.7 2004/01/18 19:06:43 minhnn Exp $
 * $Author: minhnn $
 * $Revision: 1.7 $
 * $Date: 2004/01/18 19:06:43 $
 *
 * ====================================================================
 *
 * Copyright (C) 2002-2004 by MyVietnam.net
 *
 * 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 any later version.
 *
 * All copyright notices regarding MyVietnam and MyVietnam CoreLib
 * MUST remain intact in the scripts and source code.
 *
 * 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.
 *
 * Correspondence and Marketing Questions can be sent to:
 * info@MyVietnam.net
 *
 * @author: Minh Nguyen  minhnn@MyVietnam.net
 * @author: Mai  Nguyen  mai.nh@MyVietnam.net
 */
package net.myvietnam.mvncore.filter;

import javax.servlet.http.HttpServletRequest;

import net.myvietnam.mvncore.util.StringUtil;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.regexp.RE;

public final class IPFilter {

    private static Log log = LogFactory.getLog(IPFilter.class);

    private static RE[] blockedIPs = null;

    private IPFilter() { //prevent instantiation
    }

    static {
        IPOptions ipOptions = new IPOptions();
        String[] blockedIPArray = StringUtil.getStringArray(ipOptions.blockedIP, ";");
        blockedIPs = new RE[blockedIPArray.length];
        for (int i = 0; i < blockedIPArray.length; i++) {
            String currentIPRegExp = StringUtil.replace(blockedIPArray[i], '*', "(\\d{1,3})");
            currentIPRegExp = "^" + currentIPRegExp + "$";
            try {
                log.debug("currentIPRegExp = " + currentIPRegExp);
                blockedIPs[i] = new RE(currentIPRegExp);
            } catch (Exception ex) {
                log.error("Cannot parse the regular expression = " + currentIPRegExp, ex);
            }
        }
    }

    /**
     * Filter the IP
     * @param request
     * @return true  if the IP in this request is ok
     *         false if the IP in this request is blocked
     */
    public static boolean filter(HttpServletRequest request) {
        if (request == null) {
            throw new NullPointerException("Cannot accept a null request in IPFilter");
        }
        String checkIP = request.getRemoteAddr();

        for (int i = 0; i < blockedIPs.length; i++) {
            RE currentBlockedIP = blockedIPs[i];
            if (currentBlockedIP != null) {
                synchronized (currentBlockedIP) {
                    if (currentBlockedIP.match(checkIP)) {
                        return false;
                    }
                }
            }
        }
        return true;
    }
}