001/** 002 * 003 * Copyright 2013-2014 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.javax; 018 019import java.util.ArrayList; 020import java.util.Hashtable; 021import java.util.List; 022 023import javax.naming.NamingEnumeration; 024import javax.naming.NamingException; 025import javax.naming.directory.Attribute; 026import javax.naming.directory.Attributes; 027import javax.naming.directory.DirContext; 028import javax.naming.directory.InitialDirContext; 029 030import org.jivesoftware.smack.initializer.SmackInitializer; 031import org.jivesoftware.smack.util.DNSUtil; 032import org.jivesoftware.smack.util.dns.DNSResolver; 033import org.jivesoftware.smack.util.dns.SRVRecord; 034 035/** 036 * A DNS resolver (mostly for SRV records), which makes use of the API provided in the javax.* namespace. 037 * 038 * @author Florian Schmaus 039 * 040 */ 041public class JavaxResolver implements SmackInitializer, DNSResolver { 042 043 private static JavaxResolver instance; 044 private static DirContext dirContext; 045 046 static { 047 try { 048 Hashtable<String, String> env = new Hashtable<String, String>(); 049 env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory"); 050 dirContext = new InitialDirContext(env); 051 } catch (Exception e) { 052 // Ignore. 053 } 054 055 // Try to set this DNS resolver as primary one 056 setup(); 057 } 058 059 public static synchronized DNSResolver getInstance() { 060 if (instance == null && isSupported()) { 061 instance = new JavaxResolver(); 062 } 063 return instance; 064 } 065 066 public static boolean isSupported() { 067 return dirContext != null; 068 } 069 070 public static void setup() { 071 DNSUtil.setDNSResolver(getInstance()); 072 } 073 074 @Override 075 public List<SRVRecord> lookupSRVRecords(String name) throws NamingException { 076 List<SRVRecord> res = new ArrayList<SRVRecord>(); 077 078 Attributes dnsLookup = dirContext.getAttributes(name, new String[] { "SRV" }); 079 Attribute srvAttribute = dnsLookup.get("SRV"); 080 if (srvAttribute == null) 081 return res; 082 @SuppressWarnings("unchecked") 083 NamingEnumeration<String> srvRecords = (NamingEnumeration<String>) srvAttribute.getAll(); 084 while (srvRecords.hasMore()) { 085 String srvRecordString = srvRecords.next(); 086 String[] srvRecordEntries = srvRecordString.split(" "); 087 int priority = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 4]); 088 int port = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 2]); 089 int weight = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 3]); 090 String host = srvRecordEntries[srvRecordEntries.length - 1]; 091 092 SRVRecord srvRecord = new SRVRecord(host, port, priority, weight); 093 res.add(srvRecord); 094 } 095 return res; 096 } 097 098 @Override 099 public List<Exception> initialize() { 100 setup(); 101 return null; 102 } 103 104}