NetworkUtils.java

/**
 *  OpenKM, Open Document Management System (http://www.openkm.com)
 *  Copyright (c) 2006-2011  Paco Avila & Josep Llort
 *
 *  No bytes were intentionally harmed during the development of this application.
 *
 *  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.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package com.openkm.util;

import java.io.IOException;

import org.xbill.DNS.DClass;
import org.xbill.DNS.ExtendedResolver;
import org.xbill.DNS.Message;
import org.xbill.DNS.Name;
import org.xbill.DNS.Record;
import org.xbill.DNS.Resolver;
import org.xbill.DNS.ReverseMap;
import org.xbill.DNS.Section;
import org.xbill.DNS.Type;

public class NetworkUtils {
	public static String reverseDns(String hostIp) throws IOException {
		Resolver res = new ExtendedResolver();

		Name name = ReverseMap.fromAddress(hostIp);
		int type = Type.PTR;
		int dclass = DClass.IN;
		Record rec = Record.newRecord(name, type, dclass);
		Message query = Message.newQuery(rec);
		Message response = res.send(query);

		Record[] answers = response.getSectionArray(Section.ANSWER);
		if (answers.length == 0)
			return hostIp;
		else
			return answers[0].rdataToString();
	}
}