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.List; 022import java.util.logging.Level; 023 024import javax.naming.NameNotFoundException; 025import javax.naming.NamingEnumeration; 026import javax.naming.NamingException; 027import javax.naming.directory.Attribute; 028import javax.naming.directory.Attributes; 029import javax.naming.directory.DirContext; 030import javax.naming.directory.InitialDirContext; 031 032import org.jivesoftware.smack.ConnectionConfiguration.DnssecMode; 033import org.jivesoftware.smack.initializer.SmackInitializer; 034import org.jivesoftware.smack.util.DNSUtil; 035import org.jivesoftware.smack.util.dns.DNSResolver; 036import org.jivesoftware.smack.util.dns.HostAddress; 037import org.jivesoftware.smack.util.dns.SRVRecord; 038 039import org.minidns.dnsname.DnsName; 040 041/** 042 * A DNS resolver (mostly for SRV records), which makes use of the API provided in the javax.* namespace. 043 * 044 * @author Florian Schmaus 045 * 046 */ 047public class JavaxResolver extends DNSResolver implements SmackInitializer { 048 049 private static JavaxResolver instance; 050 private static DirContext dirContext; 051 052 static { 053 try { 054 dirContext = new InitialDirContext(); 055 } catch (NamingException e) { 056 LOGGER.log(Level.SEVERE, "Could not construct InitialDirContext", e); 057 } 058 059 // Try to set this DNS resolver as primary one 060 setup(); 061 } 062 063 public static synchronized DNSResolver getInstance() { 064 if (instance == null && isSupported()) { 065 instance = new JavaxResolver(); 066 } 067 return instance; 068 } 069 070 public static boolean isSupported() { 071 return dirContext != null; 072 } 073 074 public static void setup() { 075 DNSUtil.setDNSResolver(getInstance()); 076 } 077 078 public JavaxResolver() { 079 super(false); 080 } 081 082 @Override 083 protected List<SRVRecord> lookupSRVRecords0(DnsName name, List<HostAddress> failedAddresses, DnssecMode dnssecMode) { 084 List<SRVRecord> res = null; 085 086 Attribute srvAttribute; 087 try { 088 Attributes dnsLookup = dirContext.getAttributes(name.ace, new String[] { "SRV" }); 089 srvAttribute = dnsLookup.get("SRV"); 090 if (srvAttribute == null) 091 return null; 092 } catch (NameNotFoundException e) { 093 LOGGER.log(Level.FINEST, "No DNS SRV RR found for " + name, e); 094 return null; 095 } catch (NamingException e) { 096 LOGGER.log(Level.WARNING, "Exception while resolving DNS SRV RR for " + name, e); 097 return null; 098 } 099 100 try { 101 @SuppressWarnings("unchecked") 102 NamingEnumeration<String> srvRecords = (NamingEnumeration<String>) srvAttribute.getAll(); 103 res = new ArrayList<>(); 104 while (srvRecords.hasMore()) { 105 String srvRecordString = srvRecords.next(); 106 String[] srvRecordEntries = srvRecordString.split(" "); 107 int priority = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 4]); 108 int port = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 2]); 109 int weight = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 3]); 110 String srvTarget = srvRecordEntries[srvRecordEntries.length - 1]; 111 // Strip trailing '.' from srvTarget. 112 // Later MiniDNS version may do the right thing when DnsName.from() is called with a DNS name string 113 // having a trailing dot, so this can possibly be removed in future Smack versions. 114 if (srvTarget.length() > 0 && srvTarget.charAt(srvTarget.length() - 1) == '.') { 115 srvTarget = srvTarget.substring(0, srvTarget.length() - 1); 116 } 117 DnsName host = DnsName.from(srvTarget); 118 119 List<InetAddress> hostAddresses = lookupHostAddress0(host, failedAddresses, dnssecMode); 120 if (shouldContinue(name, host, hostAddresses)) { 121 continue; 122 } 123 124 SRVRecord srvRecord = new SRVRecord(host, port, priority, weight, hostAddresses); 125 res.add(srvRecord); 126 } 127 } 128 catch (NamingException e) { 129 LOGGER.log(Level.SEVERE, "Exception while resolving DNS SRV RR for" + name, e); 130 } 131 132 return res; 133 } 134 135 @Override 136 public List<Exception> initialize() { 137 setup(); 138 return null; 139 } 140 141}