Shuyi Chen | d7955ce | 2013-05-22 14:51:55 -0700 | [diff] [blame] | 1 | // Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org) |
| 2 | |
| 3 | package org.xbill.DNS; |
| 4 | |
| 5 | import java.util.*; |
| 6 | import java.io.*; |
| 7 | import java.net.*; |
| 8 | |
| 9 | /** |
| 10 | * An implementation of Resolver that sends one query to one server. |
| 11 | * SimpleResolver handles TCP retries, transaction security (TSIG), and |
| 12 | * EDNS 0. |
| 13 | * @see Resolver |
| 14 | * @see TSIG |
| 15 | * @see OPTRecord |
| 16 | * |
| 17 | * @author Brian Wellington |
| 18 | */ |
| 19 | |
| 20 | |
| 21 | public class SimpleResolver implements Resolver { |
| 22 | |
| 23 | /** The default port to send queries to */ |
| 24 | public static final int DEFAULT_PORT = 53; |
| 25 | |
| 26 | /** The default EDNS payload size */ |
| 27 | public static final int DEFAULT_EDNS_PAYLOADSIZE = 1280; |
| 28 | |
| 29 | private InetSocketAddress address; |
| 30 | private InetSocketAddress localAddress; |
| 31 | private boolean useTCP, ignoreTruncation; |
| 32 | private OPTRecord queryOPT; |
| 33 | private TSIG tsig; |
| 34 | private long timeoutValue = 10 * 1000; |
| 35 | |
| 36 | private static final short DEFAULT_UDPSIZE = 512; |
| 37 | |
| 38 | private static String defaultResolver = "localhost"; |
| 39 | private static int uniqueID = 0; |
| 40 | |
| 41 | /** |
| 42 | * Creates a SimpleResolver that will query the specified host |
| 43 | * @exception UnknownHostException Failure occurred while finding the host |
| 44 | */ |
| 45 | public |
| 46 | SimpleResolver(String hostname) throws UnknownHostException { |
| 47 | if (hostname == null) { |
| 48 | hostname = ResolverConfig.getCurrentConfig().server(); |
| 49 | if (hostname == null) |
| 50 | hostname = defaultResolver; |
| 51 | } |
| 52 | InetAddress addr; |
| 53 | if (hostname.equals("0")) |
| 54 | addr = InetAddress.getLocalHost(); |
| 55 | else |
| 56 | addr = InetAddress.getByName(hostname); |
| 57 | address = new InetSocketAddress(addr, DEFAULT_PORT); |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * Creates a SimpleResolver. The host to query is either found by using |
| 62 | * ResolverConfig, or the default host is used. |
| 63 | * @see ResolverConfig |
| 64 | * @exception UnknownHostException Failure occurred while finding the host |
| 65 | */ |
| 66 | public |
| 67 | SimpleResolver() throws UnknownHostException { |
| 68 | this(null); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Gets the destination address associated with this SimpleResolver. |
| 73 | * Messages sent using this SimpleResolver will be sent to this address. |
| 74 | * @return The destination address associated with this SimpleResolver. |
| 75 | */ |
| 76 | InetSocketAddress |
| 77 | getAddress() { |
| 78 | return address; |
| 79 | } |
| 80 | |
| 81 | /** Sets the default host (initially localhost) to query */ |
| 82 | public static void |
| 83 | setDefaultResolver(String hostname) { |
| 84 | defaultResolver = hostname; |
| 85 | } |
| 86 | |
| 87 | public void |
| 88 | setPort(int port) { |
| 89 | address = new InetSocketAddress(address.getAddress(), port); |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Sets the address of the server to communicate with. |
| 94 | * @param addr The address of the DNS server |
| 95 | */ |
| 96 | public void |
| 97 | setAddress(InetSocketAddress addr) { |
| 98 | address = addr; |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * Sets the address of the server to communicate with (on the default |
| 103 | * DNS port) |
| 104 | * @param addr The address of the DNS server |
| 105 | */ |
| 106 | public void |
| 107 | setAddress(InetAddress addr) { |
| 108 | address = new InetSocketAddress(addr, address.getPort()); |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * Sets the local address to bind to when sending messages. |
| 113 | * @param addr The local address to send messages from. |
| 114 | */ |
| 115 | public void |
| 116 | setLocalAddress(InetSocketAddress addr) { |
| 117 | localAddress = addr; |
| 118 | } |
| 119 | |
| 120 | /** |
| 121 | * Sets the local address to bind to when sending messages. A random port |
| 122 | * will be used. |
| 123 | * @param addr The local address to send messages from. |
| 124 | */ |
| 125 | public void |
| 126 | setLocalAddress(InetAddress addr) { |
| 127 | localAddress = new InetSocketAddress(addr, 0); |
| 128 | } |
| 129 | |
| 130 | public void |
| 131 | setTCP(boolean flag) { |
| 132 | this.useTCP = flag; |
| 133 | } |
| 134 | |
| 135 | public void |
| 136 | setIgnoreTruncation(boolean flag) { |
| 137 | this.ignoreTruncation = flag; |
| 138 | } |
| 139 | |
| 140 | public void |
| 141 | setEDNS(int level, int payloadSize, int flags, List options) { |
| 142 | if (level != 0 && level != -1) |
| 143 | throw new IllegalArgumentException("invalid EDNS level - " + |
| 144 | "must be 0 or -1"); |
| 145 | if (payloadSize == 0) |
| 146 | payloadSize = DEFAULT_EDNS_PAYLOADSIZE; |
| 147 | queryOPT = new OPTRecord(payloadSize, 0, level, flags, options); |
| 148 | } |
| 149 | |
| 150 | public void |
| 151 | setEDNS(int level) { |
| 152 | setEDNS(level, 0, 0, null); |
| 153 | } |
| 154 | |
| 155 | public void |
| 156 | setTSIGKey(TSIG key) { |
| 157 | tsig = key; |
| 158 | } |
| 159 | |
| 160 | TSIG |
| 161 | getTSIGKey() { |
| 162 | return tsig; |
| 163 | } |
| 164 | |
| 165 | public void |
| 166 | setTimeout(int secs, int msecs) { |
| 167 | timeoutValue = (long)secs * 1000 + msecs; |
| 168 | } |
| 169 | |
| 170 | public void |
| 171 | setTimeout(int secs) { |
| 172 | setTimeout(secs, 0); |
| 173 | } |
| 174 | |
| 175 | long |
| 176 | getTimeout() { |
| 177 | return timeoutValue; |
| 178 | } |
| 179 | |
| 180 | private Message |
| 181 | parseMessage(byte [] b) throws WireParseException { |
| 182 | try { |
| 183 | return (new Message(b)); |
| 184 | } |
| 185 | catch (IOException e) { |
| 186 | if (Options.check("verbose")) |
| 187 | e.printStackTrace(); |
| 188 | if (!(e instanceof WireParseException)) |
| 189 | e = new WireParseException("Error parsing message"); |
| 190 | throw (WireParseException) e; |
| 191 | } |
| 192 | } |
| 193 | |
| 194 | private void |
| 195 | verifyTSIG(Message query, Message response, byte [] b, TSIG tsig) { |
| 196 | if (tsig == null) |
| 197 | return; |
| 198 | int error = tsig.verify(response, b, query.getTSIG()); |
| 199 | if (Options.check("verbose")) |
| 200 | System.err.println("TSIG verify: " + Rcode.TSIGstring(error)); |
| 201 | } |
| 202 | |
| 203 | private void |
| 204 | applyEDNS(Message query) { |
| 205 | if (queryOPT == null || query.getOPT() != null) |
| 206 | return; |
| 207 | query.addRecord(queryOPT, Section.ADDITIONAL); |
| 208 | } |
| 209 | |
| 210 | private int |
| 211 | maxUDPSize(Message query) { |
| 212 | OPTRecord opt = query.getOPT(); |
| 213 | if (opt == null) |
| 214 | return DEFAULT_UDPSIZE; |
| 215 | else |
| 216 | return opt.getPayloadSize(); |
| 217 | } |
| 218 | |
| 219 | /** |
| 220 | * Sends a message to a single server and waits for a response. No checking |
| 221 | * is done to ensure that the response is associated with the query. |
| 222 | * @param query The query to send. |
| 223 | * @return The response. |
| 224 | * @throws IOException An error occurred while sending or receiving. |
| 225 | */ |
| 226 | public Message |
| 227 | send(Message query) throws IOException { |
| 228 | if (Options.check("verbose")) |
| 229 | System.err.println("Sending to " + |
| 230 | address.getAddress().getHostAddress() + |
| 231 | ":" + address.getPort()); |
| 232 | |
| 233 | if (query.getHeader().getOpcode() == Opcode.QUERY) { |
| 234 | Record question = query.getQuestion(); |
| 235 | if (question != null && question.getType() == Type.AXFR) |
| 236 | return sendAXFR(query); |
| 237 | } |
| 238 | |
| 239 | query = (Message) query.clone(); |
| 240 | applyEDNS(query); |
| 241 | if (tsig != null) |
| 242 | tsig.apply(query, null); |
| 243 | |
| 244 | byte [] out = query.toWire(Message.MAXLENGTH); |
| 245 | int udpSize = maxUDPSize(query); |
| 246 | boolean tcp = false; |
| 247 | long endTime = System.currentTimeMillis() + timeoutValue; |
| 248 | do { |
| 249 | byte [] in; |
| 250 | |
| 251 | if (useTCP || out.length > udpSize) |
| 252 | tcp = true; |
| 253 | if (tcp) |
| 254 | in = TCPClient.sendrecv(localAddress, address, out, |
| 255 | endTime); |
| 256 | else |
| 257 | in = UDPClient.sendrecv(localAddress, address, out, |
| 258 | udpSize, endTime); |
| 259 | |
| 260 | /* |
| 261 | * Check that the response is long enough. |
| 262 | */ |
| 263 | if (in.length < Header.LENGTH) { |
| 264 | throw new WireParseException("invalid DNS header - " + |
| 265 | "too short"); |
| 266 | } |
| 267 | /* |
| 268 | * Check that the response ID matches the query ID. We want |
| 269 | * to check this before actually parsing the message, so that |
| 270 | * if there's a malformed response that's not ours, it |
| 271 | * doesn't confuse us. |
| 272 | */ |
| 273 | int id = ((in[0] & 0xFF) << 8) + (in[1] & 0xFF); |
| 274 | int qid = query.getHeader().getID(); |
| 275 | if (id != qid) { |
| 276 | String error = "invalid message id: expected " + qid + |
| 277 | "; got id " + id; |
| 278 | if (tcp) { |
| 279 | throw new WireParseException(error); |
| 280 | } else { |
| 281 | if (Options.check("verbose")) { |
| 282 | System.err.println(error); |
| 283 | } |
| 284 | continue; |
| 285 | } |
| 286 | } |
| 287 | Message response = parseMessage(in); |
| 288 | verifyTSIG(query, response, in, tsig); |
| 289 | if (!tcp && !ignoreTruncation && |
| 290 | response.getHeader().getFlag(Flags.TC)) |
| 291 | { |
| 292 | tcp = true; |
| 293 | continue; |
| 294 | } |
| 295 | return response; |
| 296 | } while (true); |
| 297 | } |
| 298 | |
| 299 | /** |
| 300 | * Asynchronously sends a message to a single server, registering a listener |
| 301 | * to receive a callback on success or exception. Multiple asynchronous |
| 302 | * lookups can be performed in parallel. Since the callback may be invoked |
| 303 | * before the function returns, external synchronization is necessary. |
| 304 | * @param query The query to send |
| 305 | * @param listener The object containing the callbacks. |
| 306 | * @return An identifier, which is also a parameter in the callback |
| 307 | */ |
| 308 | public Object |
| 309 | sendAsync(final Message query, final ResolverListener listener) { |
| 310 | final Object id; |
| 311 | synchronized (this) { |
| 312 | id = new Integer(uniqueID++); |
| 313 | } |
| 314 | Record question = query.getQuestion(); |
| 315 | String qname; |
| 316 | if (question != null) |
| 317 | qname = question.getName().toString(); |
| 318 | else |
| 319 | qname = "(none)"; |
| 320 | String name = this.getClass() + ": " + qname; |
| 321 | Thread thread = new ResolveThread(this, query, id, listener); |
| 322 | thread.setName(name); |
| 323 | thread.setDaemon(true); |
| 324 | thread.start(); |
| 325 | return id; |
| 326 | } |
| 327 | |
| 328 | private Message |
| 329 | sendAXFR(Message query) throws IOException { |
| 330 | Name qname = query.getQuestion().getName(); |
| 331 | ZoneTransferIn xfrin = ZoneTransferIn.newAXFR(qname, address, tsig); |
| 332 | xfrin.setTimeout((int)(getTimeout() / 1000)); |
| 333 | xfrin.setLocalAddress(localAddress); |
| 334 | try { |
| 335 | xfrin.run(); |
| 336 | } |
| 337 | catch (ZoneTransferException e) { |
| 338 | throw new WireParseException(e.getMessage()); |
| 339 | } |
| 340 | List records = xfrin.getAXFR(); |
| 341 | Message response = new Message(query.getHeader().getID()); |
| 342 | response.getHeader().setFlag(Flags.AA); |
| 343 | response.getHeader().setFlag(Flags.QR); |
| 344 | response.addRecord(query.getQuestion(), Section.QUESTION); |
| 345 | Iterator it = records.iterator(); |
| 346 | while (it.hasNext()) |
| 347 | response.addRecord((Record)it.next(), Section.ANSWER); |
| 348 | return response; |
| 349 | } |
| 350 | |
| 351 | } |