001/** 002 * 003 * Copyright 2013-2018 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.net.InetAddress; 020import java.util.ArrayList; 021import java.util.Hashtable; 022import java.util.List; 023import java.util.logging.Level; 024 025import javax.naming.NameNotFoundException; 026import javax.naming.NamingEnumeration; 027import javax.naming.NamingException; 028import javax.naming.directory.Attribute; 029import javax.naming.directory.Attributes; 030import javax.naming.directory.DirContext; 031import javax.naming.directory.InitialDirContext; 032 033import org.jivesoftware.smack.ConnectionConfiguration.DnssecMode; 034import org.jivesoftware.smack.initializer.SmackInitializer; 035import org.jivesoftware.smack.util.DNSUtil; 036import org.jivesoftware.smack.util.dns.DNSResolver; 037import org.jivesoftware.smack.util.dns.HostAddress; 038import org.jivesoftware.smack.util.dns.SRVRecord; 039 040import org.minidns.dnsname.DnsName; 041 042/** 043 * A DNS resolver (mostly for SRV records), which makes use of the API provided in the javax.* namespace. 044 * 045 * @author Florian Schmaus 046 * 047 */ 048public class JavaxResolver extends DNSResolver implements SmackInitializer { 049 050 private static JavaxResolver instance; 051 private static DirContext dirContext; 052 053 static { 054 try { 055 Hashtable<String, String> env = new Hashtable<>(); 056 env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory"); 057 dirContext = new InitialDirContext(env); 058 } catch (Exception e) { 059 // Ignore. 060 } 061 062 // Try to set this DNS resolver as primary one 063 setup(); 064 } 065 066 public static synchronized DNSResolver getInstance() { 067 if (instance == null && isSupported()) { 068 instance = new JavaxResolver(); 069 } 070 return instance; 071 } 072 073 public static boolean isSupported() { 074 return dirContext != null; 075 } 076 077 public static void setup() { 078 DNSUtil.setDNSResolver(getInstance()); 079 } 080 081 public JavaxResolver() { 082 super(false); 083 } 084 085 @Override 086 protected List<SRVRecord> lookupSRVRecords0(DnsName name, List<HostAddress> failedAddresses, DnssecMode dnssecMode) { 087 List<SRVRecord> res = null; 088 089 Attribute srvAttribute; 090 try { 091 Attributes dnsLookup = dirContext.getAttributes(name.ace, new String[] { "SRV" }); 092 srvAttribute = dnsLookup.get("SRV"); 093 if (srvAttribute == null) 094 return null; 095 } catch (NameNotFoundException e) { 096 LOGGER.log(Level.FINEST, "No DNS SRV RR found for " + name, e); 097 return null; 098 } catch (NamingException e) { 099 LOGGER.log(Level.WARNING, "Exception while resolving DNS SRV RR for " + name, e); 100 return null; 101 } 102 103 try { 104 @SuppressWarnings("unchecked") 105 NamingEnumeration<String> srvRecords = (NamingEnumeration<String>) srvAttribute.getAll(); 106 res = new ArrayList<>(); 107 while (srvRecords.hasMore()) { 108 String srvRecordString = srvRecords.next(); 109 String[] srvRecordEntries = srvRecordString.split(" "); 110 int priority = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 4]); 111 int port = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 2]); 112 int weight = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 3]); 113 String srvTarget = srvRecordEntries[srvRecordEntries.length - 1]; 114 // Strip trailing '.' from srvTarget. 115 // Later MiniDNS version may do the right thing when DnsName.from() is called with a DNS name string 116 // having a trailing dot, so this can possibly be removed in future Smack versions. 117 if (srvTarget.length() > 0 && srvTarget.charAt(srvTarget.length() - 1) == '.') { 118 srvTarget = srvTarget.substring(0, srvTarget.length() - 1); 119 } 120 DnsName host = DnsName.from(srvTarget); 121 122 List<InetAddress> hostAddresses = lookupHostAddress0(host, failedAddresses, dnssecMode); 123 if (shouldContinue(name, host, hostAddresses)) { 124 continue; 125 } 126 127 SRVRecord srvRecord = new SRVRecord(host, port, priority, weight, hostAddresses); 128 res.add(srvRecord); 129 } 130 } 131 catch (NamingException e) { 132 LOGGER.log(Level.SEVERE, "Exception while resolving DNS SRV RR for" + name, e); 133 } 134 135 return res; 136 } 137 138 @Override 139 public List<Exception> initialize() { 140 setup(); 141 return null; 142 } 143 144}