1 /*
2 * Copyright (c) 1995, 2011, Oracle and/or its affiliates. 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.net;
27
28 import java.util.HashMap;
29 import java.util.LinkedHashMap;
30 import java.util.Random;
31 import java.util.Iterator;
32 import java.util.LinkedList;
33 import java.util.List;
34 import java.util.ArrayList;
35 import java.util.ServiceLoader;
36 import java.security.AccessController;
37 import java.io.ObjectStreamException;
38 import java.io.IOException;
39 import java.io.ObjectInputStream;
40 import sun.security.action.*;
41 import sun.net.InetAddressCachePolicy;
42 import sun.net.util.IPAddressUtil;
43 import sun.net.spi.nameservice.*;
44
45 /**
46 * This class represents an Internet Protocol (IP) address.
47 *
48 * <p> An IP address is either a 32-bit or 128-bit unsigned number
49 * used by IP, a lower-level protocol on which protocols like UDP and
50 * TCP are built. The IP address architecture is defined by <a
51 * href="http://www.ietf.org/rfc/rfc790.txt"><i>RFC 790:
52 * Assigned Numbers</i></a>, <a
53 * href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC 1918:
54 * Address Allocation for Private Internets</i></a>, <a
55 * href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC 2365:
56 * Administratively Scoped IP Multicast</i></a>, and <a
57 * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC 2373: IP
58 * Version 6 Addressing Architecture</i></a>. An instance of an
59 * InetAddress consists of an IP address and possibly its
60 * corresponding host name (depending on whether it is constructed
61 * with a host name or whether it has already done reverse host name
62 * resolution).
63 *
64 * <h4> Address types </h4>
65 *
66 * <blockquote><table cellspacing=2 summary="Description of unicast and multicast address types">
67 * <tr><th valign=top><i>unicast</i></th>
68 * <td>An identifier for a single interface. A packet sent to
69 * a unicast address is delivered to the interface identified by
70 * that address.
71 *
72 * <p> The Unspecified Address -- Also called anylocal or wildcard
73 * address. It must never be assigned to any node. It indicates the
74 * absence of an address. One example of its use is as the target of
75 * bind, which allows a server to accept a client connection on any
76 * interface, in case the server host has multiple interfaces.
77 *
78 * <p> The <i>unspecified</i> address must not be used as
79 * the destination address of an IP packet.
80 *
81 * <p> The <i>Loopback</i> Addresses -- This is the address
82 * assigned to the loopback interface. Anything sent to this
83 * IP address loops around and becomes IP input on the local
84 * host. This address is often used when testing a
85 * client.</td></tr>
86 * <tr><th valign=top><i>multicast</i></th>
87 * <td>An identifier for a set of interfaces (typically belonging
88 * to different nodes). A packet sent to a multicast address is
89 * delivered to all interfaces identified by that address.</td></tr>
90 * </table></blockquote>
91 *
92 * <h4> IP address scope </h4>
93 *
94 * <p> <i>Link-local</i> addresses are designed to be used for addressing
95 * on a single link for purposes such as auto-address configuration,
96 * neighbor discovery, or when no routers are present.
97 *
98 * <p> <i>Site-local</i> addresses are designed to be used for addressing
99 * inside of a site without the need for a global prefix.
100 *
101 * <p> <i>Global</i> addresses are unique across the internet.
102 *
103 * <h4> Textual representation of IP addresses </h4>
104 *
105 * The textual representation of an IP address is address family specific.
106 *
107 * <p>
108 *
109 * For IPv4 address format, please refer to <A
110 * HREF="Inet4Address.html#format">Inet4Address#format</A>; For IPv6
111 * address format, please refer to <A
112 * HREF="Inet6Address.html#format">Inet6Address#format</A>.
113 *
114 * <P>There is a <a href="doc-files/net-properties.html#Ipv4IPv6">couple of
115 * System Properties</a> affecting how IPv4 and IPv6 addresses are used.</P>
116 *
117 * <h4> Host Name Resolution </h4>
118 *
119 * Host name-to-IP address <i>resolution</i> is accomplished through
120 * the use of a combination of local machine configuration information
121 * and network naming services such as the Domain Name System (DNS)
122 * and Network Information Service(NIS). The particular naming
123 * services(s) being used is by default the local machine configured
124 * one. For any host name, its corresponding IP address is returned.
125 *
126 * <p> <i>Reverse name resolution</i> means that for any IP address,
127 * the host associated with the IP address is returned.
128 *
129 * <p> The InetAddress class provides methods to resolve host names to
130 * their IP addresses and vice versa.
131 *
132 * <h4> InetAddress Caching </h4>
133 *
134 * The InetAddress class has a cache to store successful as well as
135 * unsuccessful host name resolutions.
136 *
137 * <p> By default, when a security manager is installed, in order to
138 * protect against DNS spoofing attacks,
139 * the result of positive host name resolutions are
140 * cached forever. When a security manager is not installed, the default
141 * behavior is to cache entries for a finite (implementation dependent)
142 * period of time. The result of unsuccessful host
143 * name resolution is cached for a very short period of time (10
144 * seconds) to improve performance.
145 *
146 * <p> If the default behavior is not desired, then a Java security property
147 * can be set to a different Time-to-live (TTL) value for positive
148 * caching. Likewise, a system admin can configure a different
149 * negative caching TTL value when needed.
150 *
151 * <p> Two Java security properties control the TTL values used for
152 * positive and negative host name resolution caching:
153 *
154 * <blockquote>
155 * <dl>
156 * <dt><b>networkaddress.cache.ttl</b></dt>
157 * <dd>Indicates the caching policy for successful name lookups from
158 * the name service. The value is specified as as integer to indicate
159 * the number of seconds to cache the successful lookup. The default
160 * setting is to cache for an implementation specific period of time.
161 * <p>
162 * A value of -1 indicates "cache forever".
163 * </dd>
164 * <p>
165 * <dt><b>networkaddress.cache.negative.ttl</b> (default: 10)</dt>
166 * <dd>Indicates the caching policy for un-successful name lookups
167 * from the name service. The value is specified as as integer to
168 * indicate the number of seconds to cache the failure for
169 * un-successful lookups.
170 * <p>
171 * A value of 0 indicates "never cache".
172 * A value of -1 indicates "cache forever".
173 * </dd>
174 * </dl>
175 * </blockquote>
176 *
177 * @author Chris Warth
178 * @see java.net.InetAddress#getByAddress(byte[])
179 * @see java.net.InetAddress#getByAddress(java.lang.String, byte[])
180 * @see java.net.InetAddress#getAllByName(java.lang.String)
181 * @see java.net.InetAddress#getByName(java.lang.String)
182 * @see java.net.InetAddress#getLocalHost()
183 * @since JDK1.0
184 */
185 public
186 class InetAddress implements java.io.Serializable {
187 /**
188 * Specify the address family: Internet Protocol, Version 4
189 * @since 1.4
190 */
191 static final int IPv4 = 1;
192
193 /**
194 * Specify the address family: Internet Protocol, Version 6
195 * @since 1.4
196 */
197 static final int IPv6 = 2;
198
199 /* Specify address family preference */
200 static transient boolean preferIPv6Address = false;
201
202 /**
203 * @serial
204 */
205 String hostName;
206
207 /**
208 * Holds a 32-bit IPv4 address.
209 *
210 * @serial
211 */
212 int address;
213
214 /**
215 * Specifies the address family type, for instance, '1' for IPv4
216 * addresses, and '2' for IPv6 addresses.
217 *
218 * @serial
219 */
220 int family;
221
222 /* Used to store the name service provider */
223 private static List<NameService> nameServices = null;
224
225 /* Used to store the best available hostname */
226 private transient String canonicalHostName = null;
227
228 /** use serialVersionUID from JDK 1.0.2 for interoperability */
229 private static final long serialVersionUID = 3286316764910316507L;
230
231 /*
232 * Load net library into runtime, and perform initializations.
233 */
234 static {
235 preferIPv6Address = java.security.AccessController.doPrivileged(
236 new GetBooleanAction("java.net.preferIPv6Addresses")).booleanValue();
237 AccessController.doPrivileged(new LoadLibraryAction("net"));
238 init();
239 }
240
241 /**
242 * Constructor for the Socket.accept() method.
243 * This creates an empty InetAddress, which is filled in by
244 * the accept() method. This InetAddress, however, is not
245 * put in the address cache, since it is not created by name.
246 */
247 InetAddress() {
248 }
249
250 /**
251 * Replaces the de-serialized object with an Inet4Address object.
252 *
253 * @return the alternate object to the de-serialized object.
254 *
255 * @throws ObjectStreamException if a new object replacing this
256 * object could not be created
257 */
258 private Object readResolve() throws ObjectStreamException {
259 // will replace the deserialized 'this' object
260 return new Inet4Address(this.hostName, this.address);
261 }
262
263 /**
264 * Utility routine to check if the InetAddress is an
265 * IP multicast address.
266 * @return a <code>boolean</code> indicating if the InetAddress is
267 * an IP multicast address
268 * @since JDK1.1
269 */
270 public boolean isMulticastAddress() {
271 return false;
272 }
273
274 /**
275 * Utility routine to check if the InetAddress in a wildcard address.
276 * @return a <code>boolean</code> indicating if the Inetaddress is
277 * a wildcard address.
278 * @since 1.4
279 */
280 public boolean isAnyLocalAddress() {
281 return false;
282 }
283
284 /**
285 * Utility routine to check if the InetAddress is a loopback address.
286 *
287 * @return a <code>boolean</code> indicating if the InetAddress is
288 * a loopback address; or false otherwise.
289 * @since 1.4
290 */
291 public boolean isLoopbackAddress() {
292 return false;
293 }
294
295 /**
296 * Utility routine to check if the InetAddress is an link local address.
297 *
298 * @return a <code>boolean</code> indicating if the InetAddress is
299 * a link local address; or false if address is not a link local unicast address.
300 * @since 1.4
301 */
302 public boolean isLinkLocalAddress() {
303 return false;
304 }
305
306 /**
307 * Utility routine to check if the InetAddress is a site local address.
308 *
309 * @return a <code>boolean</code> indicating if the InetAddress is
310 * a site local address; or false if address is not a site local unicast address.
311 * @since 1.4
312 */
313 public boolean isSiteLocalAddress() {
314 return false;
315 }
316
317 /**
318 * Utility routine to check if the multicast address has global scope.
319 *
320 * @return a <code>boolean</code> indicating if the address has
321 * is a multicast address of global scope, false if it is not
322 * of global scope or it is not a multicast address
323 * @since 1.4
324 */
325 public boolean isMCGlobal() {
326 return false;
327 }
328
329 /**
330 * Utility routine to check if the multicast address has node scope.
331 *
332 * @return a <code>boolean</code> indicating if the address has
333 * is a multicast address of node-local scope, false if it is not
334 * of node-local scope or it is not a multicast address
335 * @since 1.4
336 */
337 public boolean isMCNodeLocal() {
338 return false;
339 }
340
341 /**
342 * Utility routine to check if the multicast address has link scope.
343 *
344 * @return a <code>boolean</code> indicating if the address has
345 * is a multicast address of link-local scope, false if it is not
346 * of link-local scope or it is not a multicast address
347 * @since 1.4
348 */
349 public boolean isMCLinkLocal() {
350 return false;
351 }
352
353 /**
354 * Utility routine to check if the multicast address has site scope.
355 *
356 * @return a <code>boolean</code> indicating if the address has
357 * is a multicast address of site-local scope, false if it is not
358 * of site-local scope or it is not a multicast address
359 * @since 1.4
360 */
361 public boolean isMCSiteLocal() {
362 return false;
363 }
364
365 /**
366 * Utility routine to check if the multicast address has organization scope.
367 *
368 * @return a <code>boolean</code> indicating if the address has
369 * is a multicast address of organization-local scope,
370 * false if it is not of organization-local scope
371 * or it is not a multicast address
372 * @since 1.4
373 */
374 public boolean isMCOrgLocal() {
375 return false;
376 }
377
378
379 /**
380 * Test whether that address is reachable. Best effort is made by the
381 * implementation to try to reach the host, but firewalls and server
382 * configuration may block requests resulting in a unreachable status
383 * while some specific ports may be accessible.
384 * A typical implementation will use ICMP ECHO REQUESTs if the
385 * privilege can be obtained, otherwise it will try to establish
386 * a TCP connection on port 7 (Echo) of the destination host.
387 * <p>
388 * The timeout value, in milliseconds, indicates the maximum amount of time
389 * the try should take. If the operation times out before getting an
390 * answer, the host is deemed unreachable. A negative value will result
391 * in an IllegalArgumentException being thrown.
392 *
393 * @param timeout the time, in milliseconds, before the call aborts
394 * @return a <code>boolean</code> indicating if the address is reachable.
395 * @throws IOException if a network error occurs
396 * @throws IllegalArgumentException if <code>timeout</code> is negative.
397 * @since 1.5
398 */
399 public boolean isReachable(int timeout) throws IOException {
400 return isReachable(null, 0 , timeout);
401 }
402
403 /**
404 * Test whether that address is reachable. Best effort is made by the
405 * implementation to try to reach the host, but firewalls and server
406 * configuration may block requests resulting in a unreachable status
407 * while some specific ports may be accessible.
408 * A typical implementation will use ICMP ECHO REQUESTs if the
409 * privilege can be obtained, otherwise it will try to establish
410 * a TCP connection on port 7 (Echo) of the destination host.
411 * <p>
412 * The <code>network interface</code> and <code>ttl</code> parameters
413 * let the caller specify which network interface the test will go through
414 * and the maximum number of hops the packets should go through.
415 * A negative value for the <code>ttl</code> will result in an
416 * IllegalArgumentException being thrown.
417 * <p>
418 * The timeout value, in milliseconds, indicates the maximum amount of time
419 * the try should take. If the operation times out before getting an
420 * answer, the host is deemed unreachable. A negative value will result
421 * in an IllegalArgumentException being thrown.
422 *
423 * @param netif the NetworkInterface through which the
424 * test will be done, or null for any interface
425 * @param ttl the maximum numbers of hops to try or 0 for the
426 * default
427 * @param timeout the time, in milliseconds, before the call aborts
428 * @throws IllegalArgumentException if either <code>timeout</code>
429 * or <code>ttl</code> are negative.
430 * @return a <code>boolean</code>indicating if the address is reachable.
431 * @throws IOException if a network error occurs
432 * @since 1.5
433 */
434 public boolean isReachable(NetworkInterface netif, int ttl,
435 int timeout) throws IOException {
436 if (ttl < 0)
437 throw new IllegalArgumentException("ttl can't be negative");
438 if (timeout < 0)
439 throw new IllegalArgumentException("timeout can't be negative");
440
441 return impl.isReachable(this, timeout, netif, ttl);
442 }
443
444 /**
445 * Gets the host name for this IP address.
446 *
447 * <p>If this InetAddress was created with a host name,
448 * this host name will be remembered and returned;
449 * otherwise, a reverse name lookup will be performed
450 * and the result will be returned based on the system
451 * configured name lookup service. If a lookup of the name service
452 * is required, call
453 * {@link #getCanonicalHostName() getCanonicalHostName}.
454 *
455 * <p>If there is a security manager, its
456 * <code>checkConnect</code> method is first called
457 * with the hostname and <code>-1</code>
458 * as its arguments to see if the operation is allowed.
459 * If the operation is not allowed, it will return
460 * the textual representation of the IP address.
461 *
462 * @return the host name for this IP address, or if the operation
463 * is not allowed by the security check, the textual
464 * representation of the IP address.
465 *
466 * @see InetAddress#getCanonicalHostName
467 * @see SecurityManager#checkConnect
468 */
469 public String getHostName() {
470 return getHostName(true);
471 }
472
473 /**
474 * Returns the hostname for this address.
475 * If the host is equal to null, then this address refers to any
476 * of the local machine's available network addresses.
477 * this is package private so SocketPermission can make calls into
478 * here without a security check.
479 *
480 * <p>If there is a security manager, this method first
481 * calls its <code>checkConnect</code> method
482 * with the hostname and <code>-1</code>
483 * as its arguments to see if the calling code is allowed to know
484 * the hostname for this IP address, i.e., to connect to the host.
485 * If the operation is not allowed, it will return
486 * the textual representation of the IP address.
487 *
488 * @return the host name for this IP address, or if the operation
489 * is not allowed by the security check, the textual
490 * representation of the IP address.
491 *
492 * @param check make security check if true
493 *
494 * @see SecurityManager#checkConnect
495 */
496 String getHostName(boolean check) {
497 if (hostName == null) {
498 hostName = InetAddress.getHostFromNameService(this, check);
499 }
500 return hostName;
501 }
502
503 /**
504 * Gets the fully qualified domain name for this IP address.
505 * Best effort method, meaning we may not be able to return
506 * the FQDN depending on the underlying system configuration.
507 *
508 * <p>If there is a security manager, this method first
509 * calls its <code>checkConnect</code> method
510 * with the hostname and <code>-1</code>
511 * as its arguments to see if the calling code is allowed to know
512 * the hostname for this IP address, i.e., to connect to the host.
513 * If the operation is not allowed, it will return
514 * the textual representation of the IP address.
515 *
516 * @return the fully qualified domain name for this IP address,
517 * or if the operation is not allowed by the security check,
518 * the textual representation of the IP address.
519 *
520 * @see SecurityManager#checkConnect
521 *
522 * @since 1.4
523 */
524 public String getCanonicalHostName() {
525 if (canonicalHostName == null) {
526 canonicalHostName =
527 InetAddress.getHostFromNameService(this, true);
528 }
529 return canonicalHostName;
530 }
531
532 /**
533 * Returns the hostname for this address.
534 *
535 * <p>If there is a security manager, this method first
536 * calls its <code>checkConnect</code> method
537 * with the hostname and <code>-1</code>
538 * as its arguments to see if the calling code is allowed to know
539 * the hostname for this IP address, i.e., to connect to the host.
540 * If the operation is not allowed, it will return
541 * the textual representation of the IP address.
542 *
543 * @return the host name for this IP address, or if the operation
544 * is not allowed by the security check, the textual
545 * representation of the IP address.
546 *
547 * @param check make security check if true
548 *
549 * @see SecurityManager#checkConnect
550 */
551 private static String getHostFromNameService(InetAddress addr, boolean check) {
552 String host = null;
553 for (NameService nameService : nameServices) {
554 try {
555 // first lookup the hostname
556 host = nameService.getHostByAddr(addr.getAddress());
557
558 /* check to see if calling code is allowed to know
559 * the hostname for this IP address, ie, connect to the host
560 */
561 if (check) {
562 SecurityManager sec = System.getSecurityManager();
563 if (sec != null) {
564 sec.checkConnect(host, -1);
565 }
566 }
567
568 /* now get all the IP addresses for this hostname,
569 * and make sure one of them matches the original IP
570 * address. We do this to try and prevent spoofing.
571 */
572
573 InetAddress[] arr = InetAddress.getAllByName0(host, check);
574 boolean ok = false;
575
576 if(arr != null) {
577 for(int i = 0; !ok && i < arr.length; i++) {
578 ok = addr.equals(arr[i]);
579 }
580 }
581
582 //XXX: if it looks a spoof just return the address?
583 if (!ok) {
584 host = addr.getHostAddress();
585 return host;
586 }
587
588 break;
589
590 } catch (SecurityException e) {
591 host = addr.getHostAddress();
592 break;
593 } catch (UnknownHostException e) {
594 host = addr.getHostAddress();
595 // let next provider resolve the hostname
596 }
597 }
598
599 return host;
600 }
601
602 /**
603 * Returns the raw IP address of this <code>InetAddress</code>
604 * object. The result is in network byte order: the highest order
605 * byte of the address is in <code>getAddress()[0]</code>.
606 *
607 * @return the raw IP address of this object.
608 */
609 public byte[] getAddress() {
610 return null;
611 }
612
613 /**
614 * Returns the IP address string in textual presentation.
615 *
616 * @return the raw IP address in a string format.
617 * @since JDK1.0.2
618 */
619 public String getHostAddress() {
620 return null;
621 }
622
623 /**
624 * Returns a hashcode for this IP address.
625 *
626 * @return a hash code value for this IP address.
627 */
628 public int hashCode() {
629 return -1;
630 }
631
632 /**
633 * Compares this object against the specified object.
634 * The result is <code>true</code> if and only if the argument is
635 * not <code>null</code> and it represents the same IP address as
636 * this object.
637 * <p>
638 * Two instances of <code>InetAddress</code> represent the same IP
639 * address if the length of the byte arrays returned by
640 * <code>getAddress</code> is the same for both, and each of the
641 * array components is the same for the byte arrays.
642 *
643 * @param obj the object to compare against.
644 * @return <code>true</code> if the objects are the same;
645 * <code>false</code> otherwise.
646 * @see java.net.InetAddress#getAddress()
647 */
648 public boolean equals(Object obj) {
649 return false;
650 }
651
652 /**
653 * Converts this IP address to a <code>String</code>. The
654 * string returned is of the form: hostname / literal IP
655 * address.
656 *
657 * If the host name is unresolved, no reverse name service lookup
658 * is performed. The hostname part will be represented by an empty string.
659 *
660 * @return a string representation of this IP address.
661 */
662 public String toString() {
663 return ((hostName != null) ? hostName : "")
664 + "/" + getHostAddress();
665 }
666
667 /*
668 * Cached addresses - our own litle nis, not!
669 */
670 private static Cache addressCache = new Cache(Cache.Type.Positive);
671
672 private static Cache negativeCache = new Cache(Cache.Type.Negative);
673
674 private static boolean addressCacheInit = false;
675
676 static InetAddress[] unknown_array; // put THIS in cache
677
678 static InetAddressImpl impl;
679
680 private static final HashMap<String, Void> lookupTable = new HashMap<>();
681
682 /**
683 * Represents a cache entry
684 */
685 static final class CacheEntry {
686
687 CacheEntry(InetAddress[] addresses, long expiration) {
688 this.addresses = addresses;
689 this.expiration = expiration;
690 }
691
692 InetAddress[] addresses;
693 long expiration;
694 }
695
696 /**
697 * A cache that manages entries based on a policy specified
698 * at creation time.
699 */
700 static final class Cache {
701 private LinkedHashMap<String, CacheEntry> cache;
702 private Type type;
703
704 enum Type {Positive, Negative};
705
706 /**
707 * Create cache
708 */
709 public Cache(Type type) {
710 this.type = type;
711 cache = new LinkedHashMap<String, CacheEntry>();
712 }
713
714 private int getPolicy() {
715 if (type == Type.Positive) {
716 return InetAddressCachePolicy.get();
717 } else {
718 return InetAddressCachePolicy.getNegative();
719 }
720 }
721
722 /**
723 * Add an entry to the cache. If there's already an
724 * entry then for this host then the entry will be
725 * replaced.
726 */
727 public Cache put(String host, InetAddress[] addresses) {
728 int policy = getPolicy();
729 if (policy == InetAddressCachePolicy.NEVER) {
730 return this;
731 }
732
733 // purge any expired entries
734
735 if (policy != InetAddressCachePolicy.FOREVER) {
736
737 // As we iterate in insertion order we can
738 // terminate when a non-expired entry is found.
739 LinkedList<String> expired = new LinkedList<>();
740 long now = System.currentTimeMillis();
741 for (String key : cache.keySet()) {
742 CacheEntry entry = cache.get(key);
743
744 if (entry.expiration >= 0 && entry.expiration < now) {
745 expired.add(key);
746 } else {
747 break;
748 }
749 }
750
751 for (String key : expired) {
752 cache.remove(key);
753 }
754 }
755
756 // create new entry and add it to the cache
757 // -- as a HashMap replaces existing entries we
758 // don't need to explicitly check if there is
759 // already an entry for this host.
760 long expiration;
761 if (policy == InetAddressCachePolicy.FOREVER) {
762 expiration = -1;
763 } else {
764 expiration = System.currentTimeMillis() + (policy * 1000);
765 }
766 CacheEntry entry = new CacheEntry(addresses, expiration);
767 cache.put(host, entry);
768 return this;
769 }
770
771 /**
772 * Query the cache for the specific host. If found then
773 * return its CacheEntry, or null if not found.
774 */
775 public CacheEntry get(String host) {
776 int policy = getPolicy();
777 if (policy == InetAddressCachePolicy.NEVER) {
778 return null;
779 }
780 CacheEntry entry = cache.get(host);
781
782 // check if entry has expired
783 if (entry != null && policy != InetAddressCachePolicy.FOREVER) {
784 if (entry.expiration >= 0 &&
785 entry.expiration < System.currentTimeMillis()) {
786 cache.remove(host);
787 entry = null;
788 }
789 }
790
791 return entry;
792 }
793 }
794
795 /*
796 * Initialize cache and insert anyLocalAddress into the
797 * unknown array with no expiry.
798 */
799 private static void cacheInitIfNeeded() {
800 assert Thread.holdsLock(addressCache);
801 if (addressCacheInit) {
802 return;
803 }
804 unknown_array = new InetAddress[1];
805 unknown_array[0] = impl.anyLocalAddress();
806
807 addressCache.put(impl.anyLocalAddress().getHostName(),
808 unknown_array);
809
810 addressCacheInit = true;
811 }
812
813 /*
814 * Cache the given hostname and addresses.
815 */
816 private static void cacheAddresses(String hostname,
817 InetAddress[] addresses,
818 boolean success) {
819 hostname = hostname.toLowerCase();
820 synchronized (addressCache) {
821 cacheInitIfNeeded();
822 if (success) {
823 addressCache.put(hostname, addresses);
824 } else {
825 negativeCache.put(hostname, addresses);
826 }
827 }
828 }
829
830 /*
831 * Lookup hostname in cache (positive & negative cache). If
832 * found return addresses, null if not found.
833 */
834 private static InetAddress[] getCachedAddresses(String hostname) {
835 hostname = hostname.toLowerCase();
836
837 // search both positive & negative caches
838
839 synchronized (addressCache) {
840 cacheInitIfNeeded();
841
842 CacheEntry entry = addressCache.get(hostname);
843 if (entry == null) {
844 entry = negativeCache.get(hostname);
845 }
846
847 if (entry != null) {
848 return entry.addresses;
849 }
850 }
851
852 // not found
853 return null;
854 }
855
856 private static NameService createNSProvider(String provider) {
857 if (provider == null)
858 return null;
859
860 NameService nameService = null;
861 if (provider.equals("default")) {
862 // initialize the default name service
863 nameService = new NameService() {
864 public InetAddress[] lookupAllHostAddr(String host)
865 throws UnknownHostException {
866 return impl.lookupAllHostAddr(host);
867 }
868 public String getHostByAddr(byte[] addr)
869 throws UnknownHostException {
870 return impl.getHostByAddr(addr);
871 }
872 };
873 } else {
874 final String providerName = provider;
875 try {
876 nameService = java.security.AccessController.doPrivileged(
877 new java.security.PrivilegedExceptionAction<NameService>() {
878 public NameService run() {
879 Iterator<NameServiceDescriptor> itr =
880 ServiceLoader.load(NameServiceDescriptor.class)
881 .iterator();
882 while (itr.hasNext()) {
883 NameServiceDescriptor nsd = itr.next();
884 if (providerName.
885 equalsIgnoreCase(nsd.getType()+","
886 +nsd.getProviderName())) {
887 try {
888 return nsd.createNameService();
889 } catch (Exception e) {
890 e.printStackTrace();
891 System.err.println(
892 "Cannot create name service:"
893 +providerName+": " + e);
894 }
895 }
896 }
897
898 return null;
899 }
900 }
901 );
902 } catch (java.security.PrivilegedActionException e) {
903 }
904 }
905
906 return nameService;
907 }
908
909 static {
910 // create the impl
911 impl = InetAddressImplFactory.create();
912
913 // get name service if provided and requested
914 String provider = null;;
915 String propPrefix = "sun.net.spi.nameservice.provider.";
916 int n = 1;
917 nameServices = new ArrayList<NameService>();
918 provider = AccessController.doPrivileged(
919 new GetPropertyAction(propPrefix + n));
920 while (provider != null) {
921 NameService ns = createNSProvider(provider);
922 if (ns != null)
923 nameServices.add(ns);
924
925 n++;
926 provider = AccessController.doPrivileged(
927 new GetPropertyAction(propPrefix + n));
928 }
929
930 // if not designate any name services provider,
931 // create a default one
932 if (nameServices.size() == 0) {
933 NameService ns = createNSProvider("default");
934 nameServices.add(ns);
935 }
936 }
937
938 /**
939 * Creates an InetAddress based on the provided host name and IP address.
940 * No name service is checked for the validity of the address.
941 *
942 * <p> The host name can either be a machine name, such as
943 * "<code>java.sun.com</code>", or a textual representation of its IP
944 * address.
945 * <p> No validity checking is done on the host name either.
946 *
947 * <p> If addr specifies an IPv4 address an instance of Inet4Address
948 * will be returned; otherwise, an instance of Inet6Address
949 * will be returned.
950 *
951 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
952 * must be 16 bytes long
953 *
954 * @param host the specified host
955 * @param addr the raw IP address in network byte order
956 * @return an InetAddress object created from the raw IP address.
957 * @exception UnknownHostException if IP address is of illegal length
958 * @since 1.4
959 */
960 public static InetAddress getByAddress(String host, byte[] addr)
961 throws UnknownHostException {
962 if (host != null && host.length() > 0 && host.charAt(0) == '[') {
963 if (host.charAt(host.length()-1) == ']') {
964 host = host.substring(1, host.length() -1);
965 }
966 }
967 if (addr != null) {
968 if (addr.length == Inet4Address.INADDRSZ) {
969 return new Inet4Address(host, addr);
970 } else if (addr.length == Inet6Address.INADDRSZ) {
971 byte[] newAddr
972 = IPAddressUtil.convertFromIPv4MappedAddress(addr);
973 if (newAddr != null) {
974 return new Inet4Address(host, newAddr);
975 } else {
976 return new Inet6Address(host, addr);
977 }
978 }
979 }
980 throw new UnknownHostException("addr is of illegal length");
981 }
982
983
984 /**
985 * Determines the IP address of a host, given the host's name.
986 *
987 * <p> The host name can either be a machine name, such as
988 * "<code>java.sun.com</code>", or a textual representation of its
989 * IP address. If a literal IP address is supplied, only the
990 * validity of the address format is checked.
991 *
992 * <p> For <code>host</code> specified in literal IPv6 address,
993 * either the form defined in RFC 2732 or the literal IPv6 address
994 * format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
995 * supported. See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
996 * scoped addresses.
997 *
998 * <p> If the host is <tt>null</tt> then an <tt>InetAddress</tt>
999 * representing an address of the loopback interface is returned.
1000 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1001 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1002 * section 2.5.3. </p>
1003 *
1004 * @param host the specified host, or <code>null</code>.
1005 * @return an IP address for the given host name.
1006 * @exception UnknownHostException if no IP address for the
1007 * <code>host</code> could be found, or if a scope_id was specified
1008 * for a global IPv6 address.
1009 * @exception SecurityException if a security manager exists
1010 * and its checkConnect method doesn't allow the operation
1011 */
1012 public static InetAddress getByName(String host)
1013 throws UnknownHostException {
1014 return InetAddress.getAllByName(host)[0];
1015 }
1016
1017 // called from deployment cache manager
1018 private static InetAddress getByName(String host, InetAddress reqAddr)
1019 throws UnknownHostException {
1020 return InetAddress.getAllByName(host, reqAddr)[0];
1021 }
1022
1023 /**
1024 * Given the name of a host, returns an array of its IP addresses,
1025 * based on the configured name service on the system.
1026 *
1027 * <p> The host name can either be a machine name, such as
1028 * "<code>java.sun.com</code>", or a textual representation of its IP
1029 * address. If a literal IP address is supplied, only the
1030 * validity of the address format is checked.
1031 *
1032 * <p> For <code>host</code> specified in <i>literal IPv6 address</i>,
1033 * either the form defined in RFC 2732 or the literal IPv6 address
1034 * format defined in RFC 2373 is accepted. A literal IPv6 address may
1035 * also be qualified by appending a scoped zone identifier or scope_id.
1036 * The syntax and usage of scope_ids is described
1037 * <a href="Inet6Address.html#scoped">here</a>.
1038 * <p> If the host is <tt>null</tt> then an <tt>InetAddress</tt>
1039 * representing an address of the loopback interface is returned.
1040 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1041 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1042 * section 2.5.3. </p>
1043 *
1044 * <p> If there is a security manager and <code>host</code> is not
1045 * null and <code>host.length() </code> is not equal to zero, the
1046 * security manager's
1047 * <code>checkConnect</code> method is called
1048 * with the hostname and <code>-1</code>
1049 * as its arguments to see if the operation is allowed.
1050 *
1051 * @param host the name of the host, or <code>null</code>.
1052 * @return an array of all the IP addresses for a given host name.
1053 *
1054 * @exception UnknownHostException if no IP address for the
1055 * <code>host</code> could be found, or if a scope_id was specified
1056 * for a global IPv6 address.
1057 * @exception SecurityException if a security manager exists and its
1058 * <code>checkConnect</code> method doesn't allow the operation.
1059 *
1060 * @see SecurityManager#checkConnect
1061 */
1062 public static InetAddress[] getAllByName(String host)
1063 throws UnknownHostException {
1064 return getAllByName(host, null);
1065 }
1066
1067 private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
1068 throws UnknownHostException {
1069
1070 if (host == null || host.length() == 0) {
1071 InetAddress[] ret = new InetAddress[1];
1072 ret[0] = impl.loopbackAddress();
1073 return ret;
1074 }
1075
1076 boolean ipv6Expected = false;
1077 if (host.charAt(0) == '[') {
1078 // This is supposed to be an IPv6 literal
1079 if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1080 host = host.substring(1, host.length() -1);
1081 ipv6Expected = true;
1082 } else {
1083 // This was supposed to be a IPv6 address, but it's not!
1084 throw new UnknownHostException(host + ": invalid IPv6 address");
1085 }
1086 }
1087
1088 // if host is an IP address, we won't do further lookup
1089 if (Character.digit(host.charAt(0), 16) != -1
1090 || (host.charAt(0) == ':')) {
1091 byte[] addr = null;
1092 int numericZone = -1;
1093 String ifname = null;
1094 // see if it is IPv4 address
1095 addr = IPAddressUtil.textToNumericFormatV4(host);
1096 if (addr == null) {
1097 // see if it is IPv6 address
1098 // Check if a numeric or string zone id is present
1099 int pos;
1100 if ((pos=host.indexOf ("%")) != -1) {
1101 numericZone = checkNumericZone (host);
1102 if (numericZone == -1) { /* remainder of string must be an ifname */
1103 ifname = host.substring (pos+1);
1104 }
1105 }
1106 addr = IPAddressUtil.textToNumericFormatV6(host);
1107 } else if (ipv6Expected) {
1108 // Means an IPv4 litteral between brackets!
1109 throw new UnknownHostException("["+host+"]");
1110 }
1111 InetAddress[] ret = new InetAddress[1];
1112 if(addr != null) {
1113 if (addr.length == Inet4Address.INADDRSZ) {
1114 ret[0] = new Inet4Address(null, addr);
1115 } else {
1116 if (ifname != null) {
1117 ret[0] = new Inet6Address(null, addr, ifname);
1118 } else {
1119 ret[0] = new Inet6Address(null, addr, numericZone);
1120 }
1121 }
1122 return ret;
1123 }
1124 } else if (ipv6Expected) {
1125 // We were expecting an IPv6 Litteral, but got something else
1126 throw new UnknownHostException("["+host+"]");
1127 }
1128 return getAllByName0(host, reqAddr, true);
1129 }
1130
1131 /**
1132 * Returns the loopback address.
1133 * <p>
1134 * The InetAddress returned will represent the IPv4
1135 * loopback address, 127.0.0.1, or the IPv6 loopback
1136 * address, ::1. The IPv4 loopback address returned
1137 * is only one of many in the form 127.*.*.*
1138 *
1139 * @return the InetAddress loopback instance.
1140 * @since 1.7
1141 */
1142 public static InetAddress getLoopbackAddress() {
1143 return impl.loopbackAddress();
1144 }
1145
1146
1147 /**
1148 * check if the literal address string has %nn appended
1149 * returns -1 if not, or the numeric value otherwise.
1150 *
1151 * %nn may also be a string that represents the displayName of
1152 * a currently available NetworkInterface.
1153 */
1154 private static int checkNumericZone (String s) throws UnknownHostException {
1155 int percent = s.indexOf ('%');
1156 int slen = s.length();
1157 int digit, zone=0;
1158 if (percent == -1) {
1159 return -1;
1160 }
1161 for (int i=percent+1; i<slen; i++) {
1162 char c = s.charAt(i);
1163 if (c == ']') {
1164 if (i == percent+1) {
1165 /* empty per-cent field */
1166 return -1;
1167 }
1168 break;
1169 }
1170 if ((digit = Character.digit (c, 10)) < 0) {
1171 return -1;
1172 }
1173 zone = (zone * 10) + digit;
1174 }
1175 return zone;
1176 }
1177
1178 private static InetAddress[] getAllByName0 (String host)
1179 throws UnknownHostException
1180 {
1181 return getAllByName0(host, true);
1182 }
1183
1184 /**
1185 * package private so SocketPermission can call it
1186 */
1187 static InetAddress[] getAllByName0 (String host, boolean check)
1188 throws UnknownHostException {
1189 return getAllByName0 (host, null, check);
1190 }
1191
1192 private static InetAddress[] getAllByName0 (String host, InetAddress reqAddr, boolean check)
1193 throws UnknownHostException {
1194
1195 /* If it gets here it is presumed to be a hostname */
1196 /* Cache.get can return: null, unknownAddress, or InetAddress[] */
1197
1198 /* make sure the connection to the host is allowed, before we
1199 * give out a hostname
1200 */
1201 if (check) {
1202 SecurityManager security = System.getSecurityManager();
1203 if (security != null) {
1204 security.checkConnect(host, -1);
1205 }
1206 }
1207
1208 InetAddress[] addresses = getCachedAddresses(host);
1209
1210 /* If no entry in cache, then do the host lookup */
1211 if (addresses == null) {
1212 addresses = getAddressesFromNameService(host, reqAddr);
1213 }
1214
1215 if (addresses == unknown_array)
1216 throw new UnknownHostException(host);
1217
1218 return addresses.clone();
1219 }
1220
1221 private static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
1222 throws UnknownHostException
1223 {
1224 InetAddress[] addresses = null;
1225 boolean success = false;
1226 UnknownHostException ex = null;
1227
1228 // Check whether the host is in the lookupTable.
1229 // 1) If the host isn't in the lookupTable when
1230 // checkLookupTable() is called, checkLookupTable()
1231 // would add the host in the lookupTable and
1232 // return null. So we will do the lookup.
1233 // 2) If the host is in the lookupTable when
1234 // checkLookupTable() is called, the current thread
1235 // would be blocked until the host is removed
1236 // from the lookupTable. Then this thread
1237 // should try to look up the addressCache.
1238 // i) if it found the addresses in the
1239 // addressCache, checkLookupTable() would
1240 // return the addresses.
1241 // ii) if it didn't find the addresses in the
1242 // addressCache for any reason,
1243 // it should add the host in the
1244 // lookupTable and return null so the
1245 // following code would do a lookup itself.
1246 if ((addresses = checkLookupTable(host)) == null) {
1247 try {
1248 // This is the first thread which looks up the addresses
1249 // this host or the cache entry for this host has been
1250 // expired so this thread should do the lookup.
1251 for (NameService nameService : nameServices) {
1252 try {
1253 /*
1254 * Do not put the call to lookup() inside the
1255 * constructor. if you do you will still be
1256 * allocating space when the lookup fails.
1257 */
1258
1259 addresses = nameService.lookupAllHostAddr(host);
1260 success = true;
1261 break;
1262 } catch (UnknownHostException uhe) {
1263 if (host.equalsIgnoreCase("localhost")) {
1264 InetAddress[] local = new InetAddress[] { impl.loopbackAddress() };
1265 addresses = local;
1266 success = true;
1267 break;
1268 }
1269 else {
1270 addresses = unknown_array;
1271 success = false;
1272 ex = uhe;
1273 }
1274 }
1275 }
1276
1277 // More to do?
1278 if (reqAddr != null && addresses.length > 1 && !addresses[0].equals(reqAddr)) {
1279 // Find it?
1280 int i = 1;
1281 for (; i < addresses.length; i++) {
1282 if (addresses[i].equals(reqAddr)) {
1283 break;
1284 }
1285 }
1286 // Rotate
1287 if (i < addresses.length) {
1288 InetAddress tmp, tmp2 = reqAddr;
1289 for (int j = 0; j < i; j++) {
1290 tmp = addresses[j];
1291 addresses[j] = tmp2;
1292 tmp2 = tmp;
1293 }
1294 addresses[i] = tmp2;
1295 }
1296 }
1297 // Cache the address.
1298 cacheAddresses(host, addresses, success);
1299
1300 if (!success && ex != null)
1301 throw ex;
1302
1303 } finally {
1304 // Delete host from the lookupTable and notify
1305 // all threads waiting on the lookupTable monitor.
1306 updateLookupTable(host);
1307 }
1308 }
1309
1310 return addresses;
1311 }
1312
1313
1314 private static InetAddress[] checkLookupTable(String host) {
1315 synchronized (lookupTable) {
1316 // If the host isn't in the lookupTable, add it in the
1317 // lookuptable and return null. The caller should do
1318 // the lookup.
1319 if (lookupTable.containsKey(host) == false) {
1320 lookupTable.put(host, null);
1321 return null;
1322 }
1323
1324 // If the host is in the lookupTable, it means that another
1325 // thread is trying to look up the addresses of this host.
1326 // This thread should wait.
1327 while (lookupTable.containsKey(host)) {
1328 try {
1329 lookupTable.wait();
1330 } catch (InterruptedException e) {
1331 }
1332 }
1333 }
1334
1335 // The other thread has finished looking up the addresses of
1336 // the host. This thread should retry to get the addresses
1337 // from the addressCache. If it doesn't get the addresses from
1338 // the cache, it will try to look up the addresses itself.
1339 InetAddress[] addresses = getCachedAddresses(host);
1340 if (addresses == null) {
1341 synchronized (lookupTable) {
1342 lookupTable.put(host, null);
1343 return null;
1344 }
1345 }
1346
1347 return addresses;
1348 }
1349
1350 private static void updateLookupTable(String host) {
1351 synchronized (lookupTable) {
1352 lookupTable.remove(host);
1353 lookupTable.notifyAll();
1354 }
1355 }
1356
1357 /**
1358 * Returns an <code>InetAddress</code> object given the raw IP address .
1359 * The argument is in network byte order: the highest order
1360 * byte of the address is in <code>getAddress()[0]</code>.
1361 *
1362 * <p> This method doesn't block, i.e. no reverse name service lookup
1363 * is performed.
1364 *
1365 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1366 * must be 16 bytes long
1367 *
1368 * @param addr the raw IP address in network byte order
1369 * @return an InetAddress object created from the raw IP address.
1370 * @exception UnknownHostException if IP address is of illegal length
1371 * @since 1.4
1372 */
1373 public static InetAddress getByAddress(byte[] addr)
1374 throws UnknownHostException {
1375 return getByAddress(null, addr);
1376 }
1377
1378 private static InetAddress cachedLocalHost = null;
1379 private static long cacheTime = 0;
1380 private static final long maxCacheTime = 5000L;
1381 private static final Object cacheLock = new Object();
1382
1383 /**
1384 * Returns the address of the local host. This is achieved by retrieving
1385 * the name of the host from the system, then resolving that name into
1386 * an <code>InetAddress</code>.
1387 *
1388 * <P>Note: The resolved address may be cached for a short period of time.
1389 * </P>
1390 *
1391 * <p>If there is a security manager, its
1392 * <code>checkConnect</code> method is called
1393 * with the local host name and <code>-1</code>
1394 * as its arguments to see if the operation is allowed.
1395 * If the operation is not allowed, an InetAddress representing
1396 * the loopback address is returned.
1397 *
1398 * @return the address of the local host.
1399 *
1400 * @exception UnknownHostException if the local host name could not
1401 * be resolved into an address.
1402 *
1403 * @see SecurityManager#checkConnect
1404 * @see java.net.InetAddress#getByName(java.lang.String)
1405 */
1406 public static InetAddress getLocalHost() throws UnknownHostException {
1407
1408 SecurityManager security = System.getSecurityManager();
1409 try {
1410 String local = impl.getLocalHostName();
1411
1412 if (security != null) {
1413 security.checkConnect(local, -1);
1414 }
1415
1416 if (local.equals("localhost")) {
1417 return impl.loopbackAddress();
1418 }
1419
1420 InetAddress ret = null;
1421 synchronized (cacheLock) {
1422 long now = System.currentTimeMillis();
1423 if (cachedLocalHost != null) {
1424 if ((now - cacheTime) < maxCacheTime) // Less than 5s old?
1425 ret = cachedLocalHost;
1426 else
1427 cachedLocalHost = null;
1428 }
1429
1430 // we are calling getAddressesFromNameService directly
1431 // to avoid getting localHost from cache
1432 if (ret == null) {
1433 InetAddress[] localAddrs;
1434 try {
1435 localAddrs =
1436 InetAddress.getAddressesFromNameService(local, null);
1437 } catch (UnknownHostException uhe) {
1438 // Rethrow with a more informative error message.
1439 UnknownHostException uhe2 =
1440 new UnknownHostException(local + ": " +
1441 uhe.getMessage());
1442 uhe2.initCause(uhe);
1443 throw uhe2;
1444 }
1445 cachedLocalHost = localAddrs[0];
1446 cacheTime = now;
1447 ret = localAddrs[0];
1448 }
1449 }
1450 return ret;
1451 } catch (java.lang.SecurityException e) {
1452 return impl.loopbackAddress();
1453 }
1454 }
1455
1456 /**
1457 * Perform class load-time initializations.
1458 */
1459 private static native void init();
1460
1461
1462 /*
1463 * Returns the InetAddress representing anyLocalAddress
1464 * (typically 0.0.0.0 or ::0)
1465 */
1466 static InetAddress anyLocalAddress() {
1467 return impl.anyLocalAddress();
1468 }
1469
1470 /*
1471 * Load and instantiate an underlying impl class
1472 */
1473 static InetAddressImpl loadImpl(String implName) {
1474 Object impl = null;
1475
1476 /*
1477 * Property "impl.prefix" will be prepended to the classname
1478 * of the implementation object we instantiate, to which we
1479 * delegate the real work (like native methods). This
1480 * property can vary across implementations of the java.
1481 * classes. The default is an empty String "".
1482 */
1483 String prefix = AccessController.doPrivileged(
1484 new GetPropertyAction("impl.prefix", ""));
1485 try {
1486 impl = Class.forName("java.net." + prefix + implName).newInstance();
1487 } catch (ClassNotFoundException e) {
1488 System.err.println("Class not found: java.net." + prefix +
1489 implName + ":\ncheck impl.prefix property " +
1490 "in your properties file.");
1491 } catch (InstantiationException e) {
1492 System.err.println("Could not instantiate: java.net." + prefix +
1493 implName + ":\ncheck impl.prefix property " +
1494 "in your properties file.");
1495 } catch (IllegalAccessException e) {
1496 System.err.println("Cannot access class: java.net." + prefix +
1497 implName + ":\ncheck impl.prefix property " +
1498 "in your properties file.");
1499 }
1500
1501 if (impl == null) {
1502 try {
1503 impl = Class.forName(implName).newInstance();
1504 } catch (Exception e) {
1505 throw new Error("System property impl.prefix incorrect");
1506 }
1507 }
1508
1509 return (InetAddressImpl) impl;
1510 }
1511
1512 private void readObjectNoData (ObjectInputStream s) throws
1513 IOException, ClassNotFoundException {
1514 if (getClass().getClassLoader() != null) {
1515 throw new SecurityException ("invalid address type");
1516 }
1517 }
1518
1519 private void readObject (ObjectInputStream s) throws
1520 IOException, ClassNotFoundException {
1521 s.defaultReadObject ();
1522 if (getClass().getClassLoader() != null) {
1523 hostName = null;
1524 address = 0;
1525 throw new SecurityException ("invalid address type");
1526 }
1527 }
1528 }
1529
1530 /*
1531 * Simple factory to create the impl
1532 */
1533 class InetAddressImplFactory {
1534
1535 static InetAddressImpl create() {
1536 return InetAddress.loadImpl(isIPv6Supported() ?
1537 "Inet6AddressImpl" : "Inet4AddressImpl");
1538 }
1539
1540 static native boolean isIPv6Supported();
1541 }