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(
238 new java.security.PrivilegedAction<Void>() {
239 public Void run() {
240 System.loadLibrary("net");
241 return null;
242 }
243 });
244 init();
245 }
246
247 /**
248 * Constructor for the Socket.accept() method.
249 * This creates an empty InetAddress, which is filled in by
250 * the accept() method. This InetAddress, however, is not
251 * put in the address cache, since it is not created by name.
252 */
253 InetAddress() {
254 }
255
256 /**
257 * Replaces the de-serialized object with an Inet4Address object.
258 *
259 * @return the alternate object to the de-serialized object.
260 *
261 * @throws ObjectStreamException if a new object replacing this
262 * object could not be created
263 */
264 private Object readResolve() throws ObjectStreamException {
265 // will replace the deserialized 'this' object
266 return new Inet4Address(this.hostName, this.address);
267 }
268
269 /**
270 * Utility routine to check if the InetAddress is an
271 * IP multicast address.
272 * @return a <code>boolean</code> indicating if the InetAddress is
273 * an IP multicast address
274 * @since JDK1.1
275 */
276 public boolean isMulticastAddress() {
277 return false;
278 }
279
280 /**
281 * Utility routine to check if the InetAddress in a wildcard address.
282 * @return a <code>boolean</code> indicating if the Inetaddress is
283 * a wildcard address.
284 * @since 1.4
285 */
286 public boolean isAnyLocalAddress() {
287 return false;
288 }
289
290 /**
291 * Utility routine to check if the InetAddress is a loopback address.
292 *
293 * @return a <code>boolean</code> indicating if the InetAddress is
294 * a loopback address; or false otherwise.
295 * @since 1.4
296 */
297 public boolean isLoopbackAddress() {
298 return false;
299 }
300
301 /**
302 * Utility routine to check if the InetAddress is an link local address.
303 *
304 * @return a <code>boolean</code> indicating if the InetAddress is
305 * a link local address; or false if address is not a link local unicast address.
306 * @since 1.4
307 */
308 public boolean isLinkLocalAddress() {
309 return false;
310 }
311
312 /**
313 * Utility routine to check if the InetAddress is a site local address.
314 *
315 * @return a <code>boolean</code> indicating if the InetAddress is
316 * a site local address; or false if address is not a site local unicast address.
317 * @since 1.4
318 */
319 public boolean isSiteLocalAddress() {
320 return false;
321 }
322
323 /**
324 * Utility routine to check if the multicast address has global scope.
325 *
326 * @return a <code>boolean</code> indicating if the address has
327 * is a multicast address of global scope, false if it is not
328 * of global scope or it is not a multicast address
329 * @since 1.4
330 */
331 public boolean isMCGlobal() {
332 return false;
333 }
334
335 /**
336 * Utility routine to check if the multicast address has node scope.
337 *
338 * @return a <code>boolean</code> indicating if the address has
339 * is a multicast address of node-local scope, false if it is not
340 * of node-local scope or it is not a multicast address
341 * @since 1.4
342 */
343 public boolean isMCNodeLocal() {
344 return false;
345 }
346
347 /**
348 * Utility routine to check if the multicast address has link scope.
349 *
350 * @return a <code>boolean</code> indicating if the address has
351 * is a multicast address of link-local scope, false if it is not
352 * of link-local scope or it is not a multicast address
353 * @since 1.4
354 */
355 public boolean isMCLinkLocal() {
356 return false;
357 }
358
359 /**
360 * Utility routine to check if the multicast address has site scope.
361 *
362 * @return a <code>boolean</code> indicating if the address has
363 * is a multicast address of site-local scope, false if it is not
364 * of site-local scope or it is not a multicast address
365 * @since 1.4
366 */
367 public boolean isMCSiteLocal() {
368 return false;
369 }
370
371 /**
372 * Utility routine to check if the multicast address has organization scope.
373 *
374 * @return a <code>boolean</code> indicating if the address has
375 * is a multicast address of organization-local scope,
376 * false if it is not of organization-local scope
377 * or it is not a multicast address
378 * @since 1.4
379 */
380 public boolean isMCOrgLocal() {
381 return false;
382 }
383
384
385 /**
386 * Test whether that address is reachable. Best effort is made by the
387 * implementation to try to reach the host, but firewalls and server
388 * configuration may block requests resulting in a unreachable status
389 * while some specific ports may be accessible.
390 * A typical implementation will use ICMP ECHO REQUESTs if the
391 * privilege can be obtained, otherwise it will try to establish
392 * a TCP connection on port 7 (Echo) of the destination host.
393 * <p>
394 * The timeout value, in milliseconds, indicates the maximum amount of time
395 * the try should take. If the operation times out before getting an
396 * answer, the host is deemed unreachable. A negative value will result
397 * in an IllegalArgumentException being thrown.
398 *
399 * @param timeout the time, in milliseconds, before the call aborts
400 * @return a <code>boolean</code> indicating if the address is reachable.
401 * @throws IOException if a network error occurs
402 * @throws IllegalArgumentException if <code>timeout</code> is negative.
403 * @since 1.5
404 */
405 public boolean isReachable(int timeout) throws IOException {
406 return isReachable(null, 0 , timeout);
407 }
408
409 /**
410 * Test whether that address is reachable. Best effort is made by the
411 * implementation to try to reach the host, but firewalls and server
412 * configuration may block requests resulting in a unreachable status
413 * while some specific ports may be accessible.
414 * A typical implementation will use ICMP ECHO REQUESTs if the
415 * privilege can be obtained, otherwise it will try to establish
416 * a TCP connection on port 7 (Echo) of the destination host.
417 * <p>
418 * The <code>network interface</code> and <code>ttl</code> parameters
419 * let the caller specify which network interface the test will go through
420 * and the maximum number of hops the packets should go through.
421 * A negative value for the <code>ttl</code> will result in an
422 * IllegalArgumentException being thrown.
423 * <p>
424 * The timeout value, in milliseconds, indicates the maximum amount of time
425 * the try should take. If the operation times out before getting an
426 * answer, the host is deemed unreachable. A negative value will result
427 * in an IllegalArgumentException being thrown.
428 *
429 * @param netif the NetworkInterface through which the
430 * test will be done, or null for any interface
431 * @param ttl the maximum numbers of hops to try or 0 for the
432 * default
433 * @param timeout the time, in milliseconds, before the call aborts
434 * @throws IllegalArgumentException if either <code>timeout</code>
435 * or <code>ttl</code> are negative.
436 * @return a <code>boolean</code>indicating if the address is reachable.
437 * @throws IOException if a network error occurs
438 * @since 1.5
439 */
440 public boolean isReachable(NetworkInterface netif, int ttl,
441 int timeout) throws IOException {
442 if (ttl < 0)
443 throw new IllegalArgumentException("ttl can't be negative");
444 if (timeout < 0)
445 throw new IllegalArgumentException("timeout can't be negative");
446
447 return impl.isReachable(this, timeout, netif, ttl);
448 }
449
450 /**
451 * Gets the host name for this IP address.
452 *
453 * <p>If this InetAddress was created with a host name,
454 * this host name will be remembered and returned;
455 * otherwise, a reverse name lookup will be performed
456 * and the result will be returned based on the system
457 * configured name lookup service. If a lookup of the name service
458 * is required, call
459 * {@link #getCanonicalHostName() getCanonicalHostName}.
460 *
461 * <p>If there is a security manager, its
462 * <code>checkConnect</code> method is first called
463 * with the hostname and <code>-1</code>
464 * as its arguments to see if the operation is allowed.
465 * If the operation is not allowed, it will return
466 * the textual representation of the IP address.
467 *
468 * @return the host name for this IP address, or if the operation
469 * is not allowed by the security check, the textual
470 * representation of the IP address.
471 *
472 * @see InetAddress#getCanonicalHostName
473 * @see SecurityManager#checkConnect
474 */
475 public String getHostName() {
476 return getHostName(true);
477 }
478
479 /**
480 * Returns the hostname for this address.
481 * If the host is equal to null, then this address refers to any
482 * of the local machine's available network addresses.
483 * this is package private so SocketPermission can make calls into
484 * here without a security check.
485 *
486 * <p>If there is a security manager, this method first
487 * calls its <code>checkConnect</code> method
488 * with the hostname and <code>-1</code>
489 * as its arguments to see if the calling code is allowed to know
490 * the hostname for this IP address, i.e., to connect to the host.
491 * If the operation is not allowed, it will return
492 * the textual representation of the IP address.
493 *
494 * @return the host name for this IP address, or if the operation
495 * is not allowed by the security check, the textual
496 * representation of the IP address.
497 *
498 * @param check make security check if true
499 *
500 * @see SecurityManager#checkConnect
501 */
502 String getHostName(boolean check) {
503 if (hostName == null) {
504 hostName = InetAddress.getHostFromNameService(this, check);
505 }
506 return hostName;
507 }
508
509 /**
510 * Gets the fully qualified domain name for this IP address.
511 * Best effort method, meaning we may not be able to return
512 * the FQDN depending on the underlying system configuration.
513 *
514 * <p>If there is a security manager, this method first
515 * calls its <code>checkConnect</code> method
516 * with the hostname and <code>-1</code>
517 * as its arguments to see if the calling code is allowed to know
518 * the hostname for this IP address, i.e., to connect to the host.
519 * If the operation is not allowed, it will return
520 * the textual representation of the IP address.
521 *
522 * @return the fully qualified domain name for this IP address,
523 * or if the operation is not allowed by the security check,
524 * the textual representation of the IP address.
525 *
526 * @see SecurityManager#checkConnect
527 *
528 * @since 1.4
529 */
530 public String getCanonicalHostName() {
531 if (canonicalHostName == null) {
532 canonicalHostName =
533 InetAddress.getHostFromNameService(this, true);
534 }
535 return canonicalHostName;
536 }
537
538 /**
539 * Returns the hostname for this address.
540 *
541 * <p>If there is a security manager, this method first
542 * calls its <code>checkConnect</code> method
543 * with the hostname and <code>-1</code>
544 * as its arguments to see if the calling code is allowed to know
545 * the hostname for this IP address, i.e., to connect to the host.
546 * If the operation is not allowed, it will return
547 * the textual representation of the IP address.
548 *
549 * @return the host name for this IP address, or if the operation
550 * is not allowed by the security check, the textual
551 * representation of the IP address.
552 *
553 * @param check make security check if true
554 *
555 * @see SecurityManager#checkConnect
556 */
557 private static String getHostFromNameService(InetAddress addr, boolean check) {
558 String host = null;
559 for (NameService nameService : nameServices) {
560 try {
561 // first lookup the hostname
562 host = nameService.getHostByAddr(addr.getAddress());
563
564 /* check to see if calling code is allowed to know
565 * the hostname for this IP address, ie, connect to the host
566 */
567 if (check) {
568 SecurityManager sec = System.getSecurityManager();
569 if (sec != null) {
570 sec.checkConnect(host, -1);
571 }
572 }
573
574 /* now get all the IP addresses for this hostname,
575 * and make sure one of them matches the original IP
576 * address. We do this to try and prevent spoofing.
577 */
578
579 InetAddress[] arr = InetAddress.getAllByName0(host, check);
580 boolean ok = false;
581
582 if(arr != null) {
583 for(int i = 0; !ok && i < arr.length; i++) {
584 ok = addr.equals(arr[i]);
585 }
586 }
587
588 //XXX: if it looks a spoof just return the address?
589 if (!ok) {
590 host = addr.getHostAddress();
591 return host;
592 }
593
594 break;
595
596 } catch (SecurityException e) {
597 host = addr.getHostAddress();
598 break;
599 } catch (UnknownHostException e) {
600 host = addr.getHostAddress();
601 // let next provider resolve the hostname
602 }
603 }
604
605 return host;
606 }
607
608 /**
609 * Returns the raw IP address of this <code>InetAddress</code>
610 * object. The result is in network byte order: the highest order
611 * byte of the address is in <code>getAddress()[0]</code>.
612 *
613 * @return the raw IP address of this object.
614 */
615 public byte[] getAddress() {
616 return null;
617 }
618
619 /**
620 * Returns the IP address string in textual presentation.
621 *
622 * @return the raw IP address in a string format.
623 * @since JDK1.0.2
624 */
625 public String getHostAddress() {
626 return null;
627 }
628
629 /**
630 * Returns a hashcode for this IP address.
631 *
632 * @return a hash code value for this IP address.
633 */
634 public int hashCode() {
635 return -1;
636 }
637
638 /**
639 * Compares this object against the specified object.
640 * The result is <code>true</code> if and only if the argument is
641 * not <code>null</code> and it represents the same IP address as
642 * this object.
643 * <p>
644 * Two instances of <code>InetAddress</code> represent the same IP
645 * address if the length of the byte arrays returned by
646 * <code>getAddress</code> is the same for both, and each of the
647 * array components is the same for the byte arrays.
648 *
649 * @param obj the object to compare against.
650 * @return <code>true</code> if the objects are the same;
651 * <code>false</code> otherwise.
652 * @see java.net.InetAddress#getAddress()
653 */
654 public boolean equals(Object obj) {
655 return false;
656 }
657
658 /**
659 * Converts this IP address to a <code>String</code>. The
660 * string returned is of the form: hostname / literal IP
661 * address.
662 *
663 * If the host name is unresolved, no reverse name service lookup
664 * is performed. The hostname part will be represented by an empty string.
665 *
666 * @return a string representation of this IP address.
667 */
668 public String toString() {
669 return ((hostName != null) ? hostName : "")
670 + "/" + getHostAddress();
671 }
672
673 /*
674 * Cached addresses - our own litle nis, not!
675 */
676 private static Cache addressCache = new Cache(Cache.Type.Positive);
677
678 private static Cache negativeCache = new Cache(Cache.Type.Negative);
679
680 private static boolean addressCacheInit = false;
681
682 static InetAddress[] unknown_array; // put THIS in cache
683
684 static InetAddressImpl impl;
685
686 private static final HashMap<String, Void> lookupTable = new HashMap<>();
687
688 /**
689 * Represents a cache entry
690 */
691 static final class CacheEntry {
692
693 CacheEntry(InetAddress[] addresses, long expiration) {
694 this.addresses = addresses;
695 this.expiration = expiration;
696 }
697
698 InetAddress[] addresses;
699 long expiration;
700 }
701
702 /**
703 * A cache that manages entries based on a policy specified
704 * at creation time.
705 */
706 static final class Cache {
707 private LinkedHashMap<String, CacheEntry> cache;
708 private Type type;
709
710 enum Type {Positive, Negative};
711
712 /**
713 * Create cache
714 */
715 public Cache(Type type) {
716 this.type = type;
717 cache = new LinkedHashMap<String, CacheEntry>();
718 }
719
720 private int getPolicy() {
721 if (type == Type.Positive) {
722 return InetAddressCachePolicy.get();
723 } else {
724 return InetAddressCachePolicy.getNegative();
725 }
726 }
727
728 /**
729 * Add an entry to the cache. If there's already an
730 * entry then for this host then the entry will be
731 * replaced.
732 */
733 public Cache put(String host, InetAddress[] addresses) {
734 int policy = getPolicy();
735 if (policy == InetAddressCachePolicy.NEVER) {
736 return this;
737 }
738
739 // purge any expired entries
740
741 if (policy != InetAddressCachePolicy.FOREVER) {
742
743 // As we iterate in insertion order we can
744 // terminate when a non-expired entry is found.
745 LinkedList<String> expired = new LinkedList<>();
746 long now = System.currentTimeMillis();
747 for (String key : cache.keySet()) {
748 CacheEntry entry = cache.get(key);
749
750 if (entry.expiration >= 0 && entry.expiration < now) {
751 expired.add(key);
752 } else {
753 break;
754 }
755 }
756
757 for (String key : expired) {
758 cache.remove(key);
759 }
760 }
761
762 // create new entry and add it to the cache
763 // -- as a HashMap replaces existing entries we
764 // don't need to explicitly check if there is
765 // already an entry for this host.
766 long expiration;
767 if (policy == InetAddressCachePolicy.FOREVER) {
768 expiration = -1;
769 } else {
770 expiration = System.currentTimeMillis() + (policy * 1000);
771 }
772 CacheEntry entry = new CacheEntry(addresses, expiration);
773 cache.put(host, entry);
774 return this;
775 }
776
777 /**
778 * Query the cache for the specific host. If found then
779 * return its CacheEntry, or null if not found.
780 */
781 public CacheEntry get(String host) {
782 int policy = getPolicy();
783 if (policy == InetAddressCachePolicy.NEVER) {
784 return null;
785 }
786 CacheEntry entry = cache.get(host);
787
788 // check if entry has expired
789 if (entry != null && policy != InetAddressCachePolicy.FOREVER) {
790 if (entry.expiration >= 0 &&
791 entry.expiration < System.currentTimeMillis()) {
792 cache.remove(host);
793 entry = null;
794 }
795 }
796
797 return entry;
798 }
799 }
800
801 /*
802 * Initialize cache and insert anyLocalAddress into the
803 * unknown array with no expiry.
804 */
805 private static void cacheInitIfNeeded() {
806 assert Thread.holdsLock(addressCache);
807 if (addressCacheInit) {
808 return;
809 }
810 unknown_array = new InetAddress[1];
811 unknown_array[0] = impl.anyLocalAddress();
812
813 addressCache.put(impl.anyLocalAddress().getHostName(),
814 unknown_array);
815
816 addressCacheInit = true;
817 }
818
819 /*
820 * Cache the given hostname and addresses.
821 */
822 private static void cacheAddresses(String hostname,
823 InetAddress[] addresses,
824 boolean success) {
825 hostname = hostname.toLowerCase();
826 synchronized (addressCache) {
827 cacheInitIfNeeded();
828 if (success) {
829 addressCache.put(hostname, addresses);
830 } else {
831 negativeCache.put(hostname, addresses);
832 }
833 }
834 }
835
836 /*
837 * Lookup hostname in cache (positive & negative cache). If
838 * found return addresses, null if not found.
839 */
840 private static InetAddress[] getCachedAddresses(String hostname) {
841 hostname = hostname.toLowerCase();
842
843 // search both positive & negative caches
844
845 synchronized (addressCache) {
846 cacheInitIfNeeded();
847
848 CacheEntry entry = addressCache.get(hostname);
849 if (entry == null) {
850 entry = negativeCache.get(hostname);
851 }
852
853 if (entry != null) {
854 return entry.addresses;
855 }
856 }
857
858 // not found
859 return null;
860 }
861
862 private static NameService createNSProvider(String provider) {
863 if (provider == null)
864 return null;
865
866 NameService nameService = null;
867 if (provider.equals("default")) {
868 // initialize the default name service
869 nameService = new NameService() {
870 public InetAddress[] lookupAllHostAddr(String host)
871 throws UnknownHostException {
872 return impl.lookupAllHostAddr(host);
873 }
874 public String getHostByAddr(byte[] addr)
875 throws UnknownHostException {
876 return impl.getHostByAddr(addr);
877 }
878 };
879 } else {
880 final String providerName = provider;
881 try {
882 nameService = java.security.AccessController.doPrivileged(
883 new java.security.PrivilegedExceptionAction<NameService>() {
884 public NameService run() {
885 Iterator<NameServiceDescriptor> itr =
886 ServiceLoader.load(NameServiceDescriptor.class)
887 .iterator();
888 while (itr.hasNext()) {
889 NameServiceDescriptor nsd = itr.next();
890 if (providerName.
891 equalsIgnoreCase(nsd.getType()+","
892 +nsd.getProviderName())) {
893 try {
894 return nsd.createNameService();
895 } catch (Exception e) {
896 e.printStackTrace();
897 System.err.println(
898 "Cannot create name service:"
899 +providerName+": " + e);
900 }
901 }
902 }
903
904 return null;
905 }
906 }
907 );
908 } catch (java.security.PrivilegedActionException e) {
909 }
910 }
911
912 return nameService;
913 }
914
915 static {
916 // create the impl
917 impl = InetAddressImplFactory.create();
918
919 // get name service if provided and requested
920 String provider = null;;
921 String propPrefix = "sun.net.spi.nameservice.provider.";
922 int n = 1;
923 nameServices = new ArrayList<NameService>();
924 provider = AccessController.doPrivileged(
925 new GetPropertyAction(propPrefix + n));
926 while (provider != null) {
927 NameService ns = createNSProvider(provider);
928 if (ns != null)
929 nameServices.add(ns);
930
931 n++;
932 provider = AccessController.doPrivileged(
933 new GetPropertyAction(propPrefix + n));
934 }
935
936 // if not designate any name services provider,
937 // create a default one
938 if (nameServices.size() == 0) {
939 NameService ns = createNSProvider("default");
940 nameServices.add(ns);
941 }
942 }
943
944 /**
945 * Creates an InetAddress based on the provided host name and IP address.
946 * No name service is checked for the validity of the address.
947 *
948 * <p> The host name can either be a machine name, such as
949 * "<code>java.sun.com</code>", or a textual representation of its IP
950 * address.
951 * <p> No validity checking is done on the host name either.
952 *
953 * <p> If addr specifies an IPv4 address an instance of Inet4Address
954 * will be returned; otherwise, an instance of Inet6Address
955 * will be returned.
956 *
957 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
958 * must be 16 bytes long
959 *
960 * @param host the specified host
961 * @param addr the raw IP address in network byte order
962 * @return an InetAddress object created from the raw IP address.
963 * @exception UnknownHostException if IP address is of illegal length
964 * @since 1.4
965 */
966 public static InetAddress getByAddress(String host, byte[] addr)
967 throws UnknownHostException {
968 if (host != null && host.length() > 0 && host.charAt(0) == '[') {
969 if (host.charAt(host.length()-1) == ']') {
970 host = host.substring(1, host.length() -1);
971 }
972 }
973 if (addr != null) {
974 if (addr.length == Inet4Address.INADDRSZ) {
975 return new Inet4Address(host, addr);
976 } else if (addr.length == Inet6Address.INADDRSZ) {
977 byte[] newAddr
978 = IPAddressUtil.convertFromIPv4MappedAddress(addr);
979 if (newAddr != null) {
980 return new Inet4Address(host, newAddr);
981 } else {
982 return new Inet6Address(host, addr);
983 }
984 }
985 }
986 throw new UnknownHostException("addr is of illegal length");
987 }
988
989
990 /**
991 * Determines the IP address of a host, given the host's name.
992 *
993 * <p> The host name can either be a machine name, such as
994 * "<code>java.sun.com</code>", or a textual representation of its
995 * IP address. If a literal IP address is supplied, only the
996 * validity of the address format is checked.
997 *
998 * <p> For <code>host</code> specified in literal IPv6 address,
999 * either the form defined in RFC 2732 or the literal IPv6 address
1000 * format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
1001 * supported. See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
1002 * scoped addresses.
1003 *
1004 * <p> If the host is <tt>null</tt> then an <tt>InetAddress</tt>
1005 * representing an address of the loopback interface is returned.
1006 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1007 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1008 * section 2.5.3. </p>
1009 *
1010 * @param host the specified host, or <code>null</code>.
1011 * @return an IP address for the given host name.
1012 * @exception UnknownHostException if no IP address for the
1013 * <code>host</code> could be found, or if a scope_id was specified
1014 * for a global IPv6 address.
1015 * @exception SecurityException if a security manager exists
1016 * and its checkConnect method doesn't allow the operation
1017 */
1018 public static InetAddress getByName(String host)
1019 throws UnknownHostException {
1020 return InetAddress.getAllByName(host)[0];
1021 }
1022
1023 // called from deployment cache manager
1024 private static InetAddress getByName(String host, InetAddress reqAddr)
1025 throws UnknownHostException {
1026 return InetAddress.getAllByName(host, reqAddr)[0];
1027 }
1028
1029 /**
1030 * Given the name of a host, returns an array of its IP addresses,
1031 * based on the configured name service on the system.
1032 *
1033 * <p> The host name can either be a machine name, such as
1034 * "<code>java.sun.com</code>", or a textual representation of its IP
1035 * address. If a literal IP address is supplied, only the
1036 * validity of the address format is checked.
1037 *
1038 * <p> For <code>host</code> specified in <i>literal IPv6 address</i>,
1039 * either the form defined in RFC 2732 or the literal IPv6 address
1040 * format defined in RFC 2373 is accepted. A literal IPv6 address may
1041 * also be qualified by appending a scoped zone identifier or scope_id.
1042 * The syntax and usage of scope_ids is described
1043 * <a href="Inet6Address.html#scoped">here</a>.
1044 * <p> If the host is <tt>null</tt> then an <tt>InetAddress</tt>
1045 * representing an address of the loopback interface is returned.
1046 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1047 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1048 * section 2.5.3. </p>
1049 *
1050 * <p> If there is a security manager and <code>host</code> is not
1051 * null and <code>host.length() </code> is not equal to zero, the
1052 * security manager's
1053 * <code>checkConnect</code> method is called
1054 * with the hostname and <code>-1</code>
1055 * as its arguments to see if the operation is allowed.
1056 *
1057 * @param host the name of the host, or <code>null</code>.
1058 * @return an array of all the IP addresses for a given host name.
1059 *
1060 * @exception UnknownHostException if no IP address for the
1061 * <code>host</code> could be found, or if a scope_id was specified
1062 * for a global IPv6 address.
1063 * @exception SecurityException if a security manager exists and its
1064 * <code>checkConnect</code> method doesn't allow the operation.
1065 *
1066 * @see SecurityManager#checkConnect
1067 */
1068 public static InetAddress[] getAllByName(String host)
1069 throws UnknownHostException {
1070 return getAllByName(host, null);
1071 }
1072
1073 private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
1074 throws UnknownHostException {
1075
1076 if (host == null || host.length() == 0) {
1077 InetAddress[] ret = new InetAddress[1];
1078 ret[0] = impl.loopbackAddress();
1079 return ret;
1080 }
1081
1082 boolean ipv6Expected = false;
1083 if (host.charAt(0) == '[') {
1084 // This is supposed to be an IPv6 literal
1085 if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1086 host = host.substring(1, host.length() -1);
1087 ipv6Expected = true;
1088 } else {
1089 // This was supposed to be a IPv6 address, but it's not!
1090 throw new UnknownHostException(host + ": invalid IPv6 address");
1091 }
1092 }
1093
1094 // if host is an IP address, we won't do further lookup
1095 if (Character.digit(host.charAt(0), 16) != -1
1096 || (host.charAt(0) == ':')) {
1097 byte[] addr = null;
1098 int numericZone = -1;
1099 String ifname = null;
1100 // see if it is IPv4 address
1101 addr = IPAddressUtil.textToNumericFormatV4(host);
1102 if (addr == null) {
1103 // see if it is IPv6 address
1104 // Check if a numeric or string zone id is present
1105 int pos;
1106 if ((pos=host.indexOf ("%")) != -1) {
1107 numericZone = checkNumericZone (host);
1108 if (numericZone == -1) { /* remainder of string must be an ifname */
1109 ifname = host.substring (pos+1);
1110 }
1111 }
1112 addr = IPAddressUtil.textToNumericFormatV6(host);
1113 } else if (ipv6Expected) {
1114 // Means an IPv4 litteral between brackets!
1115 throw new UnknownHostException("["+host+"]");
1116 }
1117 InetAddress[] ret = new InetAddress[1];
1118 if(addr != null) {
1119 if (addr.length == Inet4Address.INADDRSZ) {
1120 ret[0] = new Inet4Address(null, addr);
1121 } else {
1122 if (ifname != null) {
1123 ret[0] = new Inet6Address(null, addr, ifname);
1124 } else {
1125 ret[0] = new Inet6Address(null, addr, numericZone);
1126 }
1127 }
1128 return ret;
1129 }
1130 } else if (ipv6Expected) {
1131 // We were expecting an IPv6 Litteral, but got something else
1132 throw new UnknownHostException("["+host+"]");
1133 }
1134 return getAllByName0(host, reqAddr, true);
1135 }
1136
1137 /**
1138 * Returns the loopback address.
1139 * <p>
1140 * The InetAddress returned will represent the IPv4
1141 * loopback address, 127.0.0.1, or the IPv6 loopback
1142 * address, ::1. The IPv4 loopback address returned
1143 * is only one of many in the form 127.*.*.*
1144 *
1145 * @return the InetAddress loopback instance.
1146 * @since 1.7
1147 */
1148 public static InetAddress getLoopbackAddress() {
1149 return impl.loopbackAddress();
1150 }
1151
1152
1153 /**
1154 * check if the literal address string has %nn appended
1155 * returns -1 if not, or the numeric value otherwise.
1156 *
1157 * %nn may also be a string that represents the displayName of
1158 * a currently available NetworkInterface.
1159 */
1160 private static int checkNumericZone (String s) throws UnknownHostException {
1161 int percent = s.indexOf ('%');
1162 int slen = s.length();
1163 int digit, zone=0;
1164 if (percent == -1) {
1165 return -1;
1166 }
1167 for (int i=percent+1; i<slen; i++) {
1168 char c = s.charAt(i);
1169 if (c == ']') {
1170 if (i == percent+1) {
1171 /* empty per-cent field */
1172 return -1;
1173 }
1174 break;
1175 }
1176 if ((digit = Character.digit (c, 10)) < 0) {
1177 return -1;
1178 }
1179 zone = (zone * 10) + digit;
1180 }
1181 return zone;
1182 }
1183
1184 private static InetAddress[] getAllByName0 (String host)
1185 throws UnknownHostException
1186 {
1187 return getAllByName0(host, true);
1188 }
1189
1190 /**
1191 * package private so SocketPermission can call it
1192 */
1193 static InetAddress[] getAllByName0 (String host, boolean check)
1194 throws UnknownHostException {
1195 return getAllByName0 (host, null, check);
1196 }
1197
1198 private static InetAddress[] getAllByName0 (String host, InetAddress reqAddr, boolean check)
1199 throws UnknownHostException {
1200
1201 /* If it gets here it is presumed to be a hostname */
1202 /* Cache.get can return: null, unknownAddress, or InetAddress[] */
1203
1204 /* make sure the connection to the host is allowed, before we
1205 * give out a hostname
1206 */
1207 if (check) {
1208 SecurityManager security = System.getSecurityManager();
1209 if (security != null) {
1210 security.checkConnect(host, -1);
1211 }
1212 }
1213
1214 InetAddress[] addresses = getCachedAddresses(host);
1215
1216 /* If no entry in cache, then do the host lookup */
1217 if (addresses == null) {
1218 addresses = getAddressesFromNameService(host, reqAddr);
1219 }
1220
1221 if (addresses == unknown_array)
1222 throw new UnknownHostException(host);
1223
1224 return addresses.clone();
1225 }
1226
1227 private static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
1228 throws UnknownHostException
1229 {
1230 InetAddress[] addresses = null;
1231 boolean success = false;
1232 UnknownHostException ex = null;
1233
1234 // Check whether the host is in the lookupTable.
1235 // 1) If the host isn't in the lookupTable when
1236 // checkLookupTable() is called, checkLookupTable()
1237 // would add the host in the lookupTable and
1238 // return null. So we will do the lookup.
1239 // 2) If the host is in the lookupTable when
1240 // checkLookupTable() is called, the current thread
1241 // would be blocked until the host is removed
1242 // from the lookupTable. Then this thread
1243 // should try to look up the addressCache.
1244 // i) if it found the addresses in the
1245 // addressCache, checkLookupTable() would
1246 // return the addresses.
1247 // ii) if it didn't find the addresses in the
1248 // addressCache for any reason,
1249 // it should add the host in the
1250 // lookupTable and return null so the
1251 // following code would do a lookup itself.
1252 if ((addresses = checkLookupTable(host)) == null) {
1253 try {
1254 // This is the first thread which looks up the addresses
1255 // this host or the cache entry for this host has been
1256 // expired so this thread should do the lookup.
1257 for (NameService nameService : nameServices) {
1258 try {
1259 /*
1260 * Do not put the call to lookup() inside the
1261 * constructor. if you do you will still be
1262 * allocating space when the lookup fails.
1263 */
1264
1265 addresses = nameService.lookupAllHostAddr(host);
1266 success = true;
1267 break;
1268 } catch (UnknownHostException uhe) {
1269 if (host.equalsIgnoreCase("localhost")) {
1270 InetAddress[] local = new InetAddress[] { impl.loopbackAddress() };
1271 addresses = local;
1272 success = true;
1273 break;
1274 }
1275 else {
1276 addresses = unknown_array;
1277 success = false;
1278 ex = uhe;
1279 }
1280 }
1281 }
1282
1283 // More to do?
1284 if (reqAddr != null && addresses.length > 1 && !addresses[0].equals(reqAddr)) {
1285 // Find it?
1286 int i = 1;
1287 for (; i < addresses.length; i++) {
1288 if (addresses[i].equals(reqAddr)) {
1289 break;
1290 }
1291 }
1292 // Rotate
1293 if (i < addresses.length) {
1294 InetAddress tmp, tmp2 = reqAddr;
1295 for (int j = 0; j < i; j++) {
1296 tmp = addresses[j];
1297 addresses[j] = tmp2;
1298 tmp2 = tmp;
1299 }
1300 addresses[i] = tmp2;
1301 }
1302 }
1303 // Cache the address.
1304 cacheAddresses(host, addresses, success);
1305
1306 if (!success && ex != null)
1307 throw ex;
1308
1309 } finally {
1310 // Delete host from the lookupTable and notify
1311 // all threads waiting on the lookupTable monitor.
1312 updateLookupTable(host);
1313 }
1314 }
1315
1316 return addresses;
1317 }
1318
1319
1320 private static InetAddress[] checkLookupTable(String host) {
1321 synchronized (lookupTable) {
1322 // If the host isn't in the lookupTable, add it in the
1323 // lookuptable and return null. The caller should do
1324 // the lookup.
1325 if (lookupTable.containsKey(host) == false) {
1326 lookupTable.put(host, null);
1327 return null;
1328 }
1329
1330 // If the host is in the lookupTable, it means that another
1331 // thread is trying to look up the addresses of this host.
1332 // This thread should wait.
1333 while (lookupTable.containsKey(host)) {
1334 try {
1335 lookupTable.wait();
1336 } catch (InterruptedException e) {
1337 }
1338 }
1339 }
1340
1341 // The other thread has finished looking up the addresses of
1342 // the host. This thread should retry to get the addresses
1343 // from the addressCache. If it doesn't get the addresses from
1344 // the cache, it will try to look up the addresses itself.
1345 InetAddress[] addresses = getCachedAddresses(host);
1346 if (addresses == null) {
1347 synchronized (lookupTable) {
1348 lookupTable.put(host, null);
1349 return null;
1350 }
1351 }
1352
1353 return addresses;
1354 }
1355
1356 private static void updateLookupTable(String host) {
1357 synchronized (lookupTable) {
1358 lookupTable.remove(host);
1359 lookupTable.notifyAll();
1360 }
1361 }
1362
1363 /**
1364 * Returns an <code>InetAddress</code> object given the raw IP address .
1365 * The argument is in network byte order: the highest order
1366 * byte of the address is in <code>getAddress()[0]</code>.
1367 *
1368 * <p> This method doesn't block, i.e. no reverse name service lookup
1369 * is performed.
1370 *
1371 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1372 * must be 16 bytes long
1373 *
1374 * @param addr the raw IP address in network byte order
1375 * @return an InetAddress object created from the raw IP address.
1376 * @exception UnknownHostException if IP address is of illegal length
1377 * @since 1.4
1378 */
1379 public static InetAddress getByAddress(byte[] addr)
1380 throws UnknownHostException {
1381 return getByAddress(null, addr);
1382 }
1383
1384 private static InetAddress cachedLocalHost = null;
1385 private static long cacheTime = 0;
1386 private static final long maxCacheTime = 5000L;
1387 private static final Object cacheLock = new Object();
1388
1389 /**
1390 * Returns the address of the local host. This is achieved by retrieving
1391 * the name of the host from the system, then resolving that name into
1392 * an <code>InetAddress</code>.
1393 *
1394 * <P>Note: The resolved address may be cached for a short period of time.
1395 * </P>
1396 *
1397 * <p>If there is a security manager, its
1398 * <code>checkConnect</code> method is called
1399 * with the local host name and <code>-1</code>
1400 * as its arguments to see if the operation is allowed.
1401 * If the operation is not allowed, an InetAddress representing
1402 * the loopback address is returned.
1403 *
1404 * @return the address of the local host.
1405 *
1406 * @exception UnknownHostException if the local host name could not
1407 * be resolved into an address.
1408 *
1409 * @see SecurityManager#checkConnect
1410 * @see java.net.InetAddress#getByName(java.lang.String)
1411 */
1412 public static InetAddress getLocalHost() throws UnknownHostException {
1413
1414 SecurityManager security = System.getSecurityManager();
1415 try {
1416 String local = impl.getLocalHostName();
1417
1418 if (security != null) {
1419 security.checkConnect(local, -1);
1420 }
1421
1422 if (local.equals("localhost")) {
1423 return impl.loopbackAddress();
1424 }
1425
1426 InetAddress ret = null;
1427 synchronized (cacheLock) {
1428 long now = System.currentTimeMillis();
1429 if (cachedLocalHost != null) {
1430 if ((now - cacheTime) < maxCacheTime) // Less than 5s old?
1431 ret = cachedLocalHost;
1432 else
1433 cachedLocalHost = null;
1434 }
1435
1436 // we are calling getAddressesFromNameService directly
1437 // to avoid getting localHost from cache
1438 if (ret == null) {
1439 InetAddress[] localAddrs;
1440 try {
1441 localAddrs =
1442 InetAddress.getAddressesFromNameService(local, null);
1443 } catch (UnknownHostException uhe) {
1444 // Rethrow with a more informative error message.
1445 UnknownHostException uhe2 =
1446 new UnknownHostException(local + ": " +
1447 uhe.getMessage());
1448 uhe2.initCause(uhe);
1449 throw uhe2;
1450 }
1451 cachedLocalHost = localAddrs[0];
1452 cacheTime = now;
1453 ret = localAddrs[0];
1454 }
1455 }
1456 return ret;
1457 } catch (java.lang.SecurityException e) {
1458 return impl.loopbackAddress();
1459 }
1460 }
1461
1462 /**
1463 * Perform class load-time initializations.
1464 */
1465 private static native void init();
1466
1467
1468 /*
1469 * Returns the InetAddress representing anyLocalAddress
1470 * (typically 0.0.0.0 or ::0)
1471 */
1472 static InetAddress anyLocalAddress() {
1473 return impl.anyLocalAddress();
1474 }
1475
1476 /*
1477 * Load and instantiate an underlying impl class
1478 */
1479 static InetAddressImpl loadImpl(String implName) {
1480 Object impl = null;
1481
1482 /*
1483 * Property "impl.prefix" will be prepended to the classname
1484 * of the implementation object we instantiate, to which we
1485 * delegate the real work (like native methods). This
1486 * property can vary across implementations of the java.
1487 * classes. The default is an empty String "".
1488 */
1489 String prefix = AccessController.doPrivileged(
1490 new GetPropertyAction("impl.prefix", ""));
1491 try {
1492 impl = Class.forName("java.net." + prefix + implName).newInstance();
1493 } catch (ClassNotFoundException e) {
1494 System.err.println("Class not found: java.net." + prefix +
1495 implName + ":\ncheck impl.prefix property " +
1496 "in your properties file.");
1497 } catch (InstantiationException e) {
1498 System.err.println("Could not instantiate: java.net." + prefix +
1499 implName + ":\ncheck impl.prefix property " +
1500 "in your properties file.");
1501 } catch (IllegalAccessException e) {
1502 System.err.println("Cannot access class: java.net." + prefix +
1503 implName + ":\ncheck impl.prefix property " +
1504 "in your properties file.");
1505 }
1506
1507 if (impl == null) {
1508 try {
1509 impl = Class.forName(implName).newInstance();
1510 } catch (Exception e) {
1511 throw new Error("System property impl.prefix incorrect");
1512 }
1513 }
1514
1515 return (InetAddressImpl) impl;
1516 }
1517
1518 private void readObjectNoData (ObjectInputStream s) throws
1519 IOException, ClassNotFoundException {
1520 if (getClass().getClassLoader() != null) {
1521 throw new SecurityException ("invalid address type");
1522 }
1523 }
1524
1525 private void readObject (ObjectInputStream s) throws
1526 IOException, ClassNotFoundException {
1527 s.defaultReadObject ();
1528 if (getClass().getClassLoader() != null) {
1529 hostName = null;
1530 address = 0;
1531 throw new SecurityException ("invalid address type");
1532 }
1533 }
1534 }
1535
1536 /*
1537 * Simple factory to create the impl
1538 */
1539 class InetAddressImplFactory {
1540
1541 static InetAddressImpl create() {
1542 return InetAddress.loadImpl(isIPv6Supported() ?
1543 "Inet6AddressImpl" : "Inet4AddressImpl");
1544 }
1545
1546 static native boolean isIPv6Supported();
1547 }