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.io.*; |
| 6 | import java.lang.reflect.*; |
| 7 | import java.util.*; |
| 8 | |
| 9 | /** |
| 10 | * A class that tries to locate name servers and the search path to |
| 11 | * be appended to unqualified names. |
| 12 | * |
| 13 | * The following are attempted, in order, until one succeeds. |
| 14 | * <UL> |
| 15 | * <LI>The properties 'dns.server' and 'dns.search' (comma delimited lists) |
| 16 | * are checked. The servers can either be IP addresses or hostnames |
| 17 | * (which are resolved using Java's built in DNS support). |
| 18 | * <LI>The sun.net.dns.ResolverConfiguration class is queried. |
| 19 | * <LI>On Unix, /etc/resolv.conf is parsed. |
| 20 | * <LI>On Windows, ipconfig/winipcfg is called and its output parsed. This |
| 21 | * may fail for non-English versions on Windows. |
| 22 | * <LI>"localhost" is used as the nameserver, and the search path is empty. |
| 23 | * </UL> |
| 24 | * |
| 25 | * These routines will be called internally when creating Resolvers/Lookups |
| 26 | * without explicitly specifying server names, and can also be called |
| 27 | * directly if desired. |
| 28 | * |
| 29 | * @author Brian Wellington |
| 30 | * @author <a href="mailto:yannick@meudal.net">Yannick Meudal</a> |
| 31 | * @author <a href="mailto:arnt@gulbrandsen.priv.no">Arnt Gulbrandsen</a> |
| 32 | */ |
| 33 | |
| 34 | public class ResolverConfig { |
| 35 | |
| 36 | private String [] servers = null; |
| 37 | private Name [] searchlist = null; |
| 38 | private int ndots = -1; |
| 39 | |
| 40 | private static ResolverConfig currentConfig; |
| 41 | |
| 42 | static { |
| 43 | refresh(); |
| 44 | } |
| 45 | |
| 46 | public |
| 47 | ResolverConfig() { |
| 48 | if (findProperty()) |
| 49 | return; |
| 50 | if (findSunJVM()) |
| 51 | return; |
| 52 | if (servers == null || searchlist == null) { |
| 53 | String OS = System.getProperty("os.name"); |
| 54 | String vendor = System.getProperty("java.vendor"); |
| 55 | if (OS.indexOf("Windows") != -1) { |
| 56 | if (OS.indexOf("95") != -1 || |
| 57 | OS.indexOf("98") != -1 || |
| 58 | OS.indexOf("ME") != -1) |
| 59 | find95(); |
| 60 | else |
| 61 | findNT(); |
| 62 | } else if (OS.indexOf("NetWare") != -1) { |
| 63 | findNetware(); |
| 64 | } else if (vendor.indexOf("Android") != -1) { |
| 65 | findAndroid(); |
| 66 | } else { |
| 67 | findUnix(); |
| 68 | } |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | private void |
| 73 | addServer(String server, List list) { |
| 74 | if (list.contains(server)) |
| 75 | return; |
| 76 | if (Options.check("verbose")) |
| 77 | System.out.println("adding server " + server); |
| 78 | list.add(server); |
| 79 | } |
| 80 | |
| 81 | private void |
| 82 | addSearch(String search, List list) { |
| 83 | Name name; |
| 84 | if (Options.check("verbose")) |
| 85 | System.out.println("adding search " + search); |
| 86 | try { |
| 87 | name = Name.fromString(search, Name.root); |
| 88 | } |
| 89 | catch (TextParseException e) { |
| 90 | return; |
| 91 | } |
| 92 | if (list.contains(name)) |
| 93 | return; |
| 94 | list.add(name); |
| 95 | } |
| 96 | |
| 97 | private int |
| 98 | parseNdots(String token) { |
| 99 | token = token.substring(6); |
| 100 | try { |
| 101 | int ndots = Integer.parseInt(token); |
| 102 | if (ndots >= 0) { |
| 103 | if (Options.check("verbose")) |
| 104 | System.out.println("setting ndots " + token); |
| 105 | return ndots; |
| 106 | } |
| 107 | } |
| 108 | catch (NumberFormatException e) { |
| 109 | } |
| 110 | return -1; |
| 111 | } |
| 112 | |
| 113 | private void |
| 114 | configureFromLists(List lserver, List lsearch) { |
| 115 | if (servers == null && lserver.size() > 0) |
| 116 | servers = (String []) lserver.toArray(new String[0]); |
| 117 | if (searchlist == null && lsearch.size() > 0) |
| 118 | searchlist = (Name []) lsearch.toArray(new Name[0]); |
| 119 | } |
| 120 | |
| 121 | private void |
| 122 | configureNdots(int lndots) { |
| 123 | if (ndots < 0 && lndots > 0) |
| 124 | ndots = lndots; |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * Looks in the system properties to find servers and a search path. |
| 129 | * Servers are defined by dns.server=server1,server2... |
| 130 | * The search path is defined by dns.search=domain1,domain2... |
| 131 | */ |
| 132 | private boolean |
| 133 | findProperty() { |
| 134 | String prop; |
| 135 | List lserver = new ArrayList(0); |
| 136 | List lsearch = new ArrayList(0); |
| 137 | StringTokenizer st; |
| 138 | |
| 139 | prop = System.getProperty("dns.server"); |
| 140 | if (prop != null) { |
| 141 | st = new StringTokenizer(prop, ","); |
| 142 | while (st.hasMoreTokens()) |
| 143 | addServer(st.nextToken(), lserver); |
| 144 | } |
| 145 | |
| 146 | prop = System.getProperty("dns.search"); |
| 147 | if (prop != null) { |
| 148 | st = new StringTokenizer(prop, ","); |
| 149 | while (st.hasMoreTokens()) |
| 150 | addSearch(st.nextToken(), lsearch); |
| 151 | } |
| 152 | configureFromLists(lserver, lsearch); |
| 153 | return (servers != null && searchlist != null); |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * Uses the undocumented Sun DNS implementation to determine the configuration. |
| 158 | * This doesn't work or even compile with all JVMs (gcj, for example). |
| 159 | */ |
| 160 | private boolean |
| 161 | findSunJVM() { |
| 162 | List lserver = new ArrayList(0); |
| 163 | List lserver_tmp; |
| 164 | List lsearch = new ArrayList(0); |
| 165 | List lsearch_tmp; |
| 166 | |
| 167 | try { |
| 168 | Class [] noClasses = new Class[0]; |
| 169 | Object [] noObjects = new Object[0]; |
| 170 | String resConfName = "sun.net.dns.ResolverConfiguration"; |
| 171 | Class resConfClass = Class.forName(resConfName); |
| 172 | Object resConf; |
| 173 | |
| 174 | // ResolverConfiguration resConf = ResolverConfiguration.open(); |
| 175 | Method open = resConfClass.getDeclaredMethod("open", noClasses); |
| 176 | resConf = open.invoke(null, noObjects); |
| 177 | |
| 178 | // lserver_tmp = resConf.nameservers(); |
| 179 | Method nameservers = resConfClass.getMethod("nameservers", |
| 180 | noClasses); |
| 181 | lserver_tmp = (List) nameservers.invoke(resConf, noObjects); |
| 182 | |
| 183 | // lsearch_tmp = resConf.searchlist(); |
| 184 | Method searchlist = resConfClass.getMethod("searchlist", |
| 185 | noClasses); |
| 186 | lsearch_tmp = (List) searchlist.invoke(resConf, noObjects); |
| 187 | } |
| 188 | catch (Exception e) { |
| 189 | return false; |
| 190 | } |
| 191 | |
| 192 | if (lserver_tmp.size() == 0) |
| 193 | return false; |
| 194 | |
| 195 | if (lserver_tmp.size() > 0) { |
| 196 | Iterator it = lserver_tmp.iterator(); |
| 197 | while (it.hasNext()) |
| 198 | addServer((String) it.next(), lserver); |
| 199 | } |
| 200 | |
| 201 | if (lsearch_tmp.size() > 0) { |
| 202 | Iterator it = lsearch_tmp.iterator(); |
| 203 | while (it.hasNext()) |
| 204 | addSearch((String) it.next(), lsearch); |
| 205 | } |
| 206 | configureFromLists(lserver, lsearch); |
| 207 | return true; |
| 208 | } |
| 209 | |
| 210 | /** |
| 211 | * Looks in /etc/resolv.conf to find servers and a search path. |
| 212 | * "nameserver" lines specify servers. "domain" and "search" lines |
| 213 | * define the search path. |
| 214 | */ |
| 215 | private void |
| 216 | findResolvConf(String file) { |
| 217 | InputStream in = null; |
| 218 | try { |
| 219 | in = new FileInputStream(file); |
| 220 | } |
| 221 | catch (FileNotFoundException e) { |
| 222 | return; |
| 223 | } |
| 224 | InputStreamReader isr = new InputStreamReader(in); |
| 225 | BufferedReader br = new BufferedReader(isr); |
| 226 | List lserver = new ArrayList(0); |
| 227 | List lsearch = new ArrayList(0); |
| 228 | int lndots = -1; |
| 229 | try { |
| 230 | String line; |
| 231 | while ((line = br.readLine()) != null) { |
| 232 | if (line.startsWith("nameserver")) { |
| 233 | StringTokenizer st = new StringTokenizer(line); |
| 234 | st.nextToken(); /* skip nameserver */ |
| 235 | addServer(st.nextToken(), lserver); |
| 236 | } |
| 237 | else if (line.startsWith("domain")) { |
| 238 | StringTokenizer st = new StringTokenizer(line); |
| 239 | st.nextToken(); /* skip domain */ |
| 240 | if (!st.hasMoreTokens()) |
| 241 | continue; |
| 242 | if (lsearch.isEmpty()) |
| 243 | addSearch(st.nextToken(), lsearch); |
| 244 | } |
| 245 | else if (line.startsWith("search")) { |
| 246 | if (!lsearch.isEmpty()) |
| 247 | lsearch.clear(); |
| 248 | StringTokenizer st = new StringTokenizer(line); |
| 249 | st.nextToken(); /* skip search */ |
| 250 | while (st.hasMoreTokens()) |
| 251 | addSearch(st.nextToken(), lsearch); |
| 252 | } |
| 253 | else if(line.startsWith("options")) { |
| 254 | StringTokenizer st = new StringTokenizer(line); |
| 255 | st.nextToken(); /* skip options */ |
| 256 | while (st.hasMoreTokens()) { |
| 257 | String token = st.nextToken(); |
| 258 | if (token.startsWith("ndots:")) { |
| 259 | lndots = parseNdots(token); |
| 260 | } |
| 261 | } |
| 262 | } |
| 263 | } |
| 264 | br.close(); |
| 265 | } |
| 266 | catch (IOException e) { |
| 267 | } |
| 268 | |
| 269 | configureFromLists(lserver, lsearch); |
| 270 | configureNdots(lndots); |
| 271 | } |
| 272 | |
| 273 | private void |
| 274 | findUnix() { |
| 275 | findResolvConf("/etc/resolv.conf"); |
| 276 | } |
| 277 | |
| 278 | private void |
| 279 | findNetware() { |
| 280 | findResolvConf("sys:/etc/resolv.cfg"); |
| 281 | } |
| 282 | |
| 283 | /** |
| 284 | * Parses the output of winipcfg or ipconfig. |
| 285 | */ |
| 286 | private void |
| 287 | findWin(InputStream in, Locale locale) { |
| 288 | String packageName = ResolverConfig.class.getPackage().getName(); |
| 289 | String resPackageName = packageName + ".windows.DNSServer"; |
| 290 | ResourceBundle res; |
| 291 | if (locale != null) |
| 292 | res = ResourceBundle.getBundle(resPackageName, locale); |
| 293 | else |
| 294 | res = ResourceBundle.getBundle(resPackageName); |
| 295 | |
| 296 | String host_name = res.getString("host_name"); |
| 297 | String primary_dns_suffix = res.getString("primary_dns_suffix"); |
| 298 | String dns_suffix = res.getString("dns_suffix"); |
| 299 | String dns_servers = res.getString("dns_servers"); |
| 300 | |
| 301 | BufferedReader br = new BufferedReader(new InputStreamReader(in)); |
| 302 | try { |
| 303 | List lserver = new ArrayList(); |
| 304 | List lsearch = new ArrayList(); |
| 305 | String line = null; |
| 306 | boolean readingServers = false; |
| 307 | boolean readingSearches = false; |
| 308 | while ((line = br.readLine()) != null) { |
| 309 | StringTokenizer st = new StringTokenizer(line); |
| 310 | if (!st.hasMoreTokens()) { |
| 311 | readingServers = false; |
| 312 | readingSearches = false; |
| 313 | continue; |
| 314 | } |
| 315 | String s = st.nextToken(); |
| 316 | if (line.indexOf(":") != -1) { |
| 317 | readingServers = false; |
| 318 | readingSearches = false; |
| 319 | } |
| 320 | |
| 321 | if (line.indexOf(host_name) != -1) { |
| 322 | while (st.hasMoreTokens()) |
| 323 | s = st.nextToken(); |
| 324 | Name name; |
| 325 | try { |
| 326 | name = Name.fromString(s, null); |
| 327 | } |
| 328 | catch (TextParseException e) { |
| 329 | continue; |
| 330 | } |
| 331 | if (name.labels() == 1) |
| 332 | continue; |
| 333 | addSearch(s, lsearch); |
| 334 | } else if (line.indexOf(primary_dns_suffix) != -1) { |
| 335 | while (st.hasMoreTokens()) |
| 336 | s = st.nextToken(); |
| 337 | if (s.equals(":")) |
| 338 | continue; |
| 339 | addSearch(s, lsearch); |
| 340 | readingSearches = true; |
| 341 | } else if (readingSearches || |
| 342 | line.indexOf(dns_suffix) != -1) |
| 343 | { |
| 344 | while (st.hasMoreTokens()) |
| 345 | s = st.nextToken(); |
| 346 | if (s.equals(":")) |
| 347 | continue; |
| 348 | addSearch(s, lsearch); |
| 349 | readingSearches = true; |
| 350 | } else if (readingServers || |
| 351 | line.indexOf(dns_servers) != -1) |
| 352 | { |
| 353 | while (st.hasMoreTokens()) |
| 354 | s = st.nextToken(); |
| 355 | if (s.equals(":")) |
| 356 | continue; |
| 357 | addServer(s, lserver); |
| 358 | readingServers = true; |
| 359 | } |
| 360 | } |
| 361 | |
| 362 | configureFromLists(lserver, lsearch); |
| 363 | } |
| 364 | catch (IOException e) { |
| 365 | } |
| 366 | return; |
| 367 | } |
| 368 | |
| 369 | private void |
| 370 | findWin(InputStream in) { |
| 371 | String property = "org.xbill.DNS.windows.parse.buffer"; |
| 372 | final int defaultBufSize = 8 * 1024; |
| 373 | int bufSize = Integer.getInteger(property, defaultBufSize).intValue(); |
| 374 | BufferedInputStream b = new BufferedInputStream(in, bufSize); |
| 375 | b.mark(bufSize); |
| 376 | findWin(b, null); |
| 377 | if (servers == null) { |
| 378 | try { |
| 379 | b.reset(); |
| 380 | } |
| 381 | catch (IOException e) { |
| 382 | return; |
| 383 | } |
| 384 | findWin(b, new Locale("", "")); |
| 385 | } |
| 386 | } |
| 387 | |
| 388 | /** |
| 389 | * Calls winipcfg and parses the result to find servers and a search path. |
| 390 | */ |
| 391 | private void |
| 392 | find95() { |
| 393 | String s = "winipcfg.out"; |
| 394 | try { |
| 395 | Process p; |
| 396 | p = Runtime.getRuntime().exec("winipcfg /all /batch " + s); |
| 397 | p.waitFor(); |
| 398 | File f = new File(s); |
| 399 | findWin(new FileInputStream(f)); |
| 400 | new File(s).delete(); |
| 401 | } |
| 402 | catch (Exception e) { |
| 403 | return; |
| 404 | } |
| 405 | } |
| 406 | |
| 407 | /** |
| 408 | * Calls ipconfig and parses the result to find servers and a search path. |
| 409 | */ |
| 410 | private void |
| 411 | findNT() { |
| 412 | try { |
| 413 | Process p; |
| 414 | p = Runtime.getRuntime().exec("ipconfig /all"); |
| 415 | findWin(p.getInputStream()); |
| 416 | p.destroy(); |
| 417 | } |
| 418 | catch (Exception e) { |
| 419 | return; |
| 420 | } |
| 421 | } |
| 422 | |
| 423 | /** |
| 424 | * Parses the output of getprop, which is the only way to get DNS |
| 425 | * info on Android. getprop might disappear in future releases, so |
| 426 | * this code comes with a use-by date. |
| 427 | */ |
| 428 | private void |
| 429 | findAndroid() { |
| 430 | // This originally looked for all lines containing .dns; but |
| 431 | // http://code.google.com/p/android/issues/detail?id=2207#c73 |
| 432 | // indicates that net.dns* should always be the active nameservers, so |
| 433 | // we use those. |
| 434 | String re1 = "^\\d+(\\.\\d+){3}$"; |
| 435 | String re2 = "^[0-9a-f]+(:[0-9a-f]*)+:[0-9a-f]+$"; |
| 436 | try { |
| 437 | ArrayList lserver = new ArrayList(); |
| 438 | ArrayList lsearch = new ArrayList(); |
| 439 | String line; |
| 440 | Process p = Runtime.getRuntime().exec("getprop"); |
| 441 | InputStream in = p.getInputStream(); |
| 442 | InputStreamReader isr = new InputStreamReader(in); |
| 443 | BufferedReader br = new BufferedReader(isr); |
| 444 | while ((line = br.readLine()) != null ) { |
| 445 | StringTokenizer t = new StringTokenizer(line, ":"); |
| 446 | String name = t.nextToken(); |
| 447 | if (name.indexOf( "net.dns" ) > -1) { |
| 448 | String v = t.nextToken(); |
| 449 | v = v.replaceAll("[ \\[\\]]", ""); |
| 450 | if ((v.matches(re1) || v.matches(re2)) && |
| 451 | !lserver.contains(v)) |
| 452 | lserver.add(v); |
| 453 | } |
| 454 | } |
| 455 | configureFromLists(lserver, lsearch); |
| 456 | } catch ( Exception e ) { |
| 457 | // ignore resolutely |
| 458 | } |
| 459 | } |
| 460 | |
| 461 | /** Returns all located servers */ |
| 462 | public String [] |
| 463 | servers() { |
| 464 | return servers; |
| 465 | } |
| 466 | |
| 467 | /** Returns the first located server */ |
| 468 | public String |
| 469 | server() { |
| 470 | if (servers == null) |
| 471 | return null; |
| 472 | return servers[0]; |
| 473 | } |
| 474 | |
| 475 | /** Returns all entries in the located search path */ |
| 476 | public Name [] |
| 477 | searchPath() { |
| 478 | return searchlist; |
| 479 | } |
| 480 | |
| 481 | /** |
| 482 | * Returns the located ndots value, or the default (1) if not configured. |
| 483 | * Note that ndots can only be configured in a resolv.conf file, and will only |
| 484 | * take effect if ResolverConfig uses resolv.conf directly (that is, if the |
| 485 | * JVM does not include the sun.net.dns.ResolverConfiguration class). |
| 486 | */ |
| 487 | public int |
| 488 | ndots() { |
| 489 | if (ndots < 0) |
| 490 | return 1; |
| 491 | return ndots; |
| 492 | } |
| 493 | |
| 494 | /** Gets the current configuration */ |
| 495 | public static synchronized ResolverConfig |
| 496 | getCurrentConfig() { |
| 497 | return currentConfig; |
| 498 | } |
| 499 | |
| 500 | /** Gets the current configuration */ |
| 501 | public static void |
| 502 | refresh() { |
| 503 | ResolverConfig newConfig = new ResolverConfig(); |
| 504 | synchronized (ResolverConfig.class) { |
| 505 | currentConfig = newConfig; |
| 506 | } |
| 507 | } |
| 508 | |
| 509 | } |