001/** 002 * 003 * Copyright 2013-2019 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 * Note that using JavaxResovler requires applications using newer Java versions (at least 11) to declare a dependency on the "sun.jdk" module. 045 * 046 * @author Florian Schmaus 047 * 048 */ 049public class JavaxResolver extends DNSResolver implements SmackInitializer { 050 051 private static JavaxResolver instance; 052 private static DirContext dirContext; 053 054 static { 055 try { 056 Hashtable<String, String> env = new Hashtable<>(); 057 env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory"); 058 dirContext = new InitialDirContext(env); 059 } catch (NamingException e) { 060 LOGGER.log(Level.SEVERE, "Could not construct InitialDirContext", e); 061 } 062 063 // Try to set this DNS resolver as primary one 064 setup(); 065 } 066 067 public static synchronized DNSResolver getInstance() { 068 if (instance == null && isSupported()) { 069 instance = new JavaxResolver(); 070 } 071 return instance; 072 } 073 074 public static boolean isSupported() { 075 return dirContext != null; 076 } 077 078 public static void setup() { 079 DNSUtil.setDNSResolver(getInstance()); 080 } 081 082 public JavaxResolver() { 083 super(false); 084 } 085 086 @Override 087 protected List<SRVRecord> lookupSRVRecords0(DnsName name, List<HostAddress> failedAddresses, DnssecMode dnssecMode) { 088 List<SRVRecord> res = null; 089 090 Attribute srvAttribute; 091 try { 092 Attributes dnsLookup = dirContext.getAttributes(name.ace, new String[] { "SRV" }); 093 srvAttribute = dnsLookup.get("SRV"); 094 if (srvAttribute == null) 095 return null; 096 } catch (NameNotFoundException e) { 097 LOGGER.log(Level.FINEST, "No DNS SRV RR found for " + name, e); 098 return null; 099 } catch (NamingException e) { 100 LOGGER.log(Level.WARNING, "Exception while resolving DNS SRV RR for " + name, e); 101 return null; 102 } 103 104 try { 105 @SuppressWarnings("unchecked") 106 NamingEnumeration<String> srvRecords = (NamingEnumeration<String>) srvAttribute.getAll(); 107 res = new ArrayList<>(); 108 while (srvRecords.hasMore()) { 109 String srvRecordString = srvRecords.next(); 110 String[] srvRecordEntries = srvRecordString.split(" "); 111 int priority = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 4]); 112 int port = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 2]); 113 int weight = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 3]); 114 String srvTarget = srvRecordEntries[srvRecordEntries.length - 1]; 115 // Strip trailing '.' from srvTarget. 116 // Later MiniDNS version may do the right thing when DnsName.from() is called with a DNS name string 117 // having a trailing dot, so this can possibly be removed in future Smack versions. 118 if (srvTarget.length() > 0 && srvTarget.charAt(srvTarget.length() - 1) == '.') { 119 srvTarget = srvTarget.substring(0, srvTarget.length() - 1); 120 } 121 DnsName host = DnsName.from(srvTarget); 122 123 List<InetAddress> hostAddresses = lookupHostAddress0(host, failedAddresses, dnssecMode); 124 if (shouldContinue(name, host, hostAddresses)) { 125 continue; 126 } 127 128 SRVRecord srvRecord = new SRVRecord(host, port, priority, weight, hostAddresses); 129 res.add(srvRecord); 130 } 131 } 132 catch (NamingException e) { 133 LOGGER.log(Level.SEVERE, "Exception while resolving DNS SRV RR for" + name, e); 134 } 135 136 return res; 137 } 138 139 @Override 140 public List<Exception> initialize() { 141 setup(); 142 return null; 143 } 144 145}