J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2000-2007 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package com.sun.jndi.dns; |
| 27 | |
| 28 | |
| 29 | import javax.naming.*; |
| 30 | |
| 31 | |
| 32 | /** |
| 33 | * The Resolver class performs DNS client operations in support of DnsContext. |
| 34 | * |
| 35 | * <p> Every DnsName instance passed to or returned from a method of |
| 36 | * this class should be fully-qualified and contain a root label (an |
| 37 | * empty component at position 0). |
| 38 | * |
| 39 | * @author Scott Seligman |
| 40 | */ |
| 41 | |
| 42 | class Resolver { |
| 43 | |
| 44 | private DnsClient dnsClient; |
| 45 | private int timeout; // initial timeout on UDP queries in ms |
| 46 | private int retries; // number of UDP retries |
| 47 | |
| 48 | |
| 49 | /* |
| 50 | * Constructs a new Resolver given its servers and timeout parameters. |
| 51 | * Each server is of the form "server[:port]". |
| 52 | * IPv6 literal host names include delimiting brackets. |
| 53 | * There must be at least one server. |
| 54 | * "timeout" is the initial timeout interval (in ms) for UDP queries, |
| 55 | * and "retries" gives the number of retries per server. |
| 56 | */ |
| 57 | Resolver(String[] servers, int timeout, int retries) |
| 58 | throws NamingException { |
| 59 | this.timeout = timeout; |
| 60 | this.retries = retries; |
| 61 | dnsClient = new DnsClient(servers, timeout, retries); |
| 62 | } |
| 63 | |
| 64 | public void close() { |
| 65 | dnsClient.close(); |
| 66 | dnsClient = null; |
| 67 | } |
| 68 | |
| 69 | |
| 70 | /* |
| 71 | * Queries resource records of a particular class and type for a |
| 72 | * given domain name. |
| 73 | * Useful values of rrclass are ResourceRecord.[Q]CLASS_xxx. |
| 74 | * Useful values of rrtype are ResourceRecord.[Q]TYPE_xxx. |
| 75 | * If recursion is true, recursion is requested on the query. |
| 76 | * If auth is true, only authoritative responses are accepted. |
| 77 | */ |
| 78 | ResourceRecords query(DnsName fqdn, int rrclass, int rrtype, |
| 79 | boolean recursion, boolean auth) |
| 80 | throws NamingException { |
| 81 | return dnsClient.query(fqdn, rrclass, rrtype, recursion, auth); |
| 82 | } |
| 83 | |
| 84 | /* |
| 85 | * Queries all resource records of a zone given its domain name and class. |
| 86 | * If recursion is true, recursion is requested on the query to find |
| 87 | * the name server (and also on the zone transfer, but it won't matter). |
| 88 | */ |
| 89 | ResourceRecords queryZone(DnsName zone, int rrclass, boolean recursion) |
| 90 | throws NamingException { |
| 91 | |
| 92 | DnsClient cl = |
| 93 | new DnsClient(findNameServers(zone, recursion), timeout, retries); |
| 94 | try { |
| 95 | return cl.queryZone(zone, rrclass, recursion); |
| 96 | } finally { |
| 97 | cl.close(); |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | /* |
| 102 | * Finds the zone of a given domain name. The method is to look |
| 103 | * for the first SOA record on the path from the given domain to |
| 104 | * the root. This search may be partially bypassed if the zone's |
| 105 | * SOA record is received in the authority section of a response. |
| 106 | * If recursion is true, recursion is requested on any queries. |
| 107 | */ |
| 108 | DnsName findZoneName(DnsName fqdn, int rrclass, boolean recursion) |
| 109 | throws NamingException { |
| 110 | |
| 111 | fqdn = (DnsName) fqdn.clone(); |
| 112 | while (fqdn.size() > 1) { // while below root |
| 113 | ResourceRecords rrs = null; |
| 114 | try { |
| 115 | rrs = query(fqdn, rrclass, ResourceRecord.TYPE_SOA, |
| 116 | recursion, false); |
| 117 | } catch (NameNotFoundException e) { |
| 118 | throw e; |
| 119 | } catch (NamingException e) { |
| 120 | // Ignore error and keep searching up the tree. |
| 121 | } |
| 122 | if (rrs != null) { |
| 123 | if (rrs.answer.size() > 0) { // found zone's SOA |
| 124 | return fqdn; |
| 125 | } |
| 126 | // Look for an SOA record giving the zone's top node. |
| 127 | for (int i = 0; i < rrs.authority.size(); i++) { |
| 128 | ResourceRecord rr = (ResourceRecord) |
| 129 | rrs.authority.elementAt(i); |
| 130 | if (rr.getType() == ResourceRecord.TYPE_SOA) { |
| 131 | DnsName zone = rr.getName(); |
| 132 | if (fqdn.endsWith(zone)) { |
| 133 | return zone; |
| 134 | } |
| 135 | } |
| 136 | } |
| 137 | } |
| 138 | fqdn.remove(fqdn.size() - 1); // one step rootward |
| 139 | } |
| 140 | return fqdn; // no SOA found below root, so |
| 141 | // return root |
| 142 | } |
| 143 | |
| 144 | /* |
| 145 | * Finds a zone's SOA record. Returns null if no SOA is found (in |
| 146 | * which case "zone" is not actually a zone). |
| 147 | * If recursion is true, recursion is requested on the query. |
| 148 | */ |
| 149 | ResourceRecord findSoa(DnsName zone, int rrclass, boolean recursion) |
| 150 | throws NamingException { |
| 151 | |
| 152 | ResourceRecords rrs = query(zone, rrclass, ResourceRecord.TYPE_SOA, |
| 153 | recursion, false); |
| 154 | for (int i = 0; i < rrs.answer.size(); i++) { |
| 155 | ResourceRecord rr = (ResourceRecord) rrs.answer.elementAt(i); |
| 156 | if (rr.getType() == ResourceRecord.TYPE_SOA) { |
| 157 | return rr; |
| 158 | } |
| 159 | } |
| 160 | return null; |
| 161 | } |
| 162 | |
| 163 | /* |
| 164 | * Finds the name servers of a zone. <tt>zone</tt> is a fully-qualified |
| 165 | * domain name at the top of a zone. |
| 166 | * If recursion is true, recursion is requested on the query. |
| 167 | */ |
| 168 | private String[] findNameServers(DnsName zone, boolean recursion) |
| 169 | throws NamingException { |
| 170 | |
| 171 | // %%% As an optimization, could look in authority section of |
| 172 | // findZoneName() response first. |
| 173 | ResourceRecords rrs = |
| 174 | query(zone, ResourceRecord.CLASS_INTERNET, ResourceRecord.TYPE_NS, |
| 175 | recursion, false); |
| 176 | String[] ns = new String[rrs.answer.size()]; |
| 177 | for (int i = 0; i < ns.length; i++) { |
| 178 | ResourceRecord rr = (ResourceRecord) |
| 179 | rrs.answer.elementAt(i); |
| 180 | if (rr.getType() != ResourceRecord.TYPE_NS) { |
| 181 | throw new CommunicationException("Corrupted DNS message"); |
| 182 | } |
| 183 | ns[i] = (String) rr.getRdata(); |
| 184 | |
| 185 | // Server name will be passed to InetAddress.getByName(), which |
| 186 | // may not be able to handle a trailing dot. |
| 187 | // assert ns[i].endsWith("."); |
| 188 | ns[i] = ns[i].substring(0, ns[i].length() - 1); |
| 189 | } |
| 190 | return ns; |
| 191 | } |
| 192 | } |