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 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you under the Apache License, Version 2.0 (the            *
 * "License"); you may not use this file except in compliance   *
 * with the License.  You may obtain a copy of the License at   *
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 * software distributed under the License is distributed on an  *
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
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package org.apache.james.transport.matchers;

import org.apache.mailet.GenericMatcher;
import org.apache.mailet.Mail;

import javax.mail.MessagingException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Collection;
import java.util.StringTokenizer;

/**
 * Checks the network IP address of the sending server against a
 * blacklist of spammers.  There are 3 lists that support this...
 * <ul>
 * <li><b>blackholes.mail-abuse.org</b>: Rejected - see  http://www.mail-abuse.org/rbl/
 * <li><b>dialups.mail-abuse.org</b>: Dialup - see http://www.mail-abuse.org/dul/
 * <li><b>relays.mail-abuse.org</b>: Open spam relay - see http://www.mail-abuse.org/rss/
 * </ul>
 *
 * Example:
 * <mailet match="InSpammerBlacklist=blackholes.mail-abuse.org" class="ToProcessor">
 *   <processor>spam</processor>
 * </mailet>
 *
 */
public class InSpammerBlacklist extends GenericMatcher {
    String network = null;

    public void init() throws MessagingException {
        network = getCondition();
    }

    public Collection match(Mail mail) {
        String host = mail.getRemoteAddr();
        try {
            //Have to reverse the octets first
            StringBuffer sb = new StringBuffer();
            StringTokenizer st = new StringTokenizer(host, " .", false);

            while (st.hasMoreTokens()) {
                sb.insert(0, st.nextToken() + ".");
            }

            //Add the network prefix for this blacklist
            sb.append(network);

            //Try to look it up
            org.apache.james.dnsserver.DNSServer.getByName(sb.toString());

            //If we got here, that's bad... it means the host
            //  was found in the blacklist
            return mail.getRecipients();
        } catch (UnknownHostException uhe) {
            //This is good... it's not on the list
            return null;
        }
    }
}