dns.java

Java Mail Server JAVA编写的邮件服务器

/****************************************************************
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.     *
 *                                                              *
 * Copyright 2008 Jun Li(SiChuan University, the School of      *
 * Software Engineering). All rights reserved.                  *
 *                                                              *
 * Licensed to the JMS under one  or more contributor license   *
 * agreements.  See the LICENCE file  distributed with this     *
 * work for additional information regarding copyright          *
 * ownership.  The JMS licenses this file  you may not use this *
 * file except in compliance  with the License.                 *
 *                                                              *
 * Unless required by applicable law or agreed to in writing,   *
 * software distributed under the License is distributed on an  *
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
 * KIND, either express or implied.  See the License for the    *
 * specific language governing permissions and limitations      *
 * under the License.                                           *
 ****************************************************************/
package org.jpxx.mail.Dns;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import org.apache.log4j.Logger;
import org.jpxx.mail.Factory;
import org.xbill.DNS.*;

/**
 * Resolve an mx record from a dns server.  
 * The dnsjava library is used as the resolver this class is a simple wrapper
 * 
 * @author Jun Li
 * @version $Revision: 0.0.1 $, $Date: 2008/04/25 8:16:00 $
 * 
 */
public class DNS {

    /**
     * Creates an instance of Logger and initializes it. 
     * It is to write log for <code>DNS</code>.
     */
    private static Logger log = Factory.getSingletonInstance().getLogger(DNS.class);

    /**
     * Given a domain will return all the mailservers used to send
     * mail to the given domain.   
     * Need to order the list by preference listed in the dns server.
     * This works by using the dnsjava library as the resolver.
     * 
     * @param domain The destnation server domain(or IP)
     * @return all the mailservers used to send mail to the given domain.
     */
    public static synchronized ArrayList getMailServer(String domain) {
        ArrayList servers = new ArrayList();
        Record foundServers[];

        try {
            foundServers = new Lookup(domain, Type.MX).run();

            /**
             * Put the servers into the server list
             */
            if (foundServers != null) {
                for (int i = 0; i < foundServers.length; i++) {
                    MXRecord m = (MXRecord) foundServers[i];
                    /**
                     * Need to add in order of preference
                     */
                    servers.add(m.getTarget().toString());
                }
            }
        } catch (Exception e) {
            log.error(e.getMessage());
        }

        return servers;
    }

    /**
     * Determines the IP address of a host, given the host's name.
     *
     * <p> The host name can either be a machine name, such as
     * "<code>java.sun.com</code>", or a textual representation of its
     * IP address. If a literal IP address is supplied, only the
     * validity of the address format is checked.
     *
     * <p> For <code>host</code> specified in literal IPv6 address,
     * either the form defined in RFC 2732 or the literal IPv6 address
     * format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
     * supported.
     *
     * <p> If the host is <tt>null</tt> then an <tt>InetAddress</tt>
     * representing an address of the loopback interface is returned.
     * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC&nbsp;3330</a>
     * section&nbsp;2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">
     * RFC&nbsp;2373</a>
     * section&nbsp;2.5.3. </p>
     *
     * @param      host   the specified host, or <code>null</code>.
     * @return     an IP address for the given host name.
     * @exception  UnknownHostException  if no IP address for the
     *               <code>host</code> could be found, or if a scope_id was 
     *              specified for a global IPv6 address.
     * @exception  SecurityException if a security manager exists
     *             and its checkConnect method doesn't allow the operation
     */
    public static InetAddress getByName(String host)
            throws UnknownHostException {
        if (host == null || host.trim().equals("")) {
            return null;
        }

        if (host.endsWith(".")) {
            host = host.substring(0, host.length() - 1);
        }
        return InetAddress.getByName(host);
    }

    /**
     * 
     * @param host
     * @return
     * @throws org.xbill.DNS.TextParseException
     */
    public static String[] getHostIP(String host) throws TextParseException {
        Record record[] = new Lookup(host, Type.A).run();

        if (record == null) {
            return null;
        }
        String ip[] = new String[record.length];
        for (int i = 0; i < record.length; i++) {
            ip[i] = record[i].rdataToString();
        }
        return ip;
    }
    
    /**
     * 
     * @param host
     * @return
     * @throws org.xbill.DNS.TextParseException
     */
    public static String[] getMXHostIP(String host)
            throws TextParseException {
        ArrayList result = new ArrayList();
        ArrayList list = getMailServer(host);
        for (int i = 0; i < list.size(); i++) {
            String hostIP[] = getHostIP(list.get(i).toString());
            if (hostIP != null) {
                for (int j = 0; j < hostIP.length; j++) {
                    result.add(hostIP[j]);
                }
            }
        }
        if (result.size() == 0) {
            return null;
        } else {
            String ip[] = new String[result.size()];
            result.toArray(ip);
            return ip;
        }
    }
}