001/**
002 *
003 * Copyright 2014 Florian Schmaus
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smack.util.dns.minidns;
018
019import java.util.LinkedList;
020import java.util.List;
021
022import org.jivesoftware.smack.initializer.SmackInitializer;
023import org.jivesoftware.smack.util.DNSUtil;
024import org.jivesoftware.smack.util.dns.DNSResolver;
025import org.jivesoftware.smack.util.dns.SRVRecord;
026import org.jxmpp.util.cache.ExpirationCache;
027
028import de.measite.minidns.Client;
029import de.measite.minidns.DNSCache;
030import de.measite.minidns.DNSMessage;
031import de.measite.minidns.Question;
032import de.measite.minidns.Record;
033import de.measite.minidns.Record.CLASS;
034import de.measite.minidns.Record.TYPE;
035import de.measite.minidns.record.SRV;
036
037
038/**
039 * This implementation uses the <a href="https://github.com/rtreffer/minidns/">minidns</a> implementation for
040 * resolving DNS addresses.
041 */
042public class MiniDnsResolver implements SmackInitializer, DNSResolver {
043
044    private static final long ONE_DAY = 24*60*60*1000;
045    private static final MiniDnsResolver instance = new MiniDnsResolver();
046    private static final ExpirationCache<Question, DNSMessage> cache = new ExpirationCache<Question, DNSMessage>(10, ONE_DAY);
047    private final Client client; 
048
049    public MiniDnsResolver() {
050        client = new Client(new DNSCache() {
051
052            @Override
053            public DNSMessage get(Question question) {
054                return cache.get(question);
055            }
056
057            @Override
058            public void put(Question question, DNSMessage message) {
059                long expirationTime = ONE_DAY;
060                for (Record record : message.getAnswers()) {
061                    if (record.isAnswer(question)) {
062                        expirationTime = record.getTtl();
063                        break;
064                    }
065                }
066                cache.put(question, message, expirationTime);
067            }
068
069        });
070    }
071
072    public static DNSResolver getInstance() {
073        return instance;
074    }
075
076    @Override
077    public List<SRVRecord> lookupSRVRecords(String name) {
078        List<SRVRecord> res = new LinkedList<SRVRecord>();
079        DNSMessage message = client.query(name, TYPE.SRV, CLASS.IN);
080        if (message == null) {
081            return res;
082        }
083        for (Record record : message.getAnswers()) {
084            SRV srv = (SRV) record.getPayload();
085            res.add(new SRVRecord(srv.getName(), srv.getPort(), srv.getPriority(), srv.getWeight()));
086        }
087        return res;
088    }
089
090    public static void setup() {
091        DNSUtil.setDNSResolver(getInstance());
092    }
093
094    @Override
095    public List<Exception> initialize() {
096        setup();
097        return null;
098    }
099
100}