package org.ibex.mail;
import java.io.*;
import java.util.*;
import java.net.*;
import org.xbill.DNS.*;
import org.xbill.DNS.Message;

public class DNSUtil {

    public static String reverseLookup(InetAddress ip) throws IOException {
        Resolver res = new ExtendedResolver();
        Message response =
            res.send(Message.newQuery(Record.newRecord(ReverseMap.fromAddress(ip), Type.PTR, DClass.IN)));
        Record[] answers = response.getSectionArray(Section.ANSWER);
        return answers.length==0 ? null : answers[0].rdataToString();
    }

}