1 /*
2 * Copyright (c) 1995, 2013, 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.ObjectStreamField;
39 import java.io.IOException;
40 import java.io.ObjectInputStream;
41 import java.io.ObjectInputStream.GetField;
42 import java.io.ObjectOutputStream;
43 import java.io.ObjectOutputStream.PutField;
44 import sun.security.action.*;
45 import sun.net.InetAddressCachePolicy;
46 import sun.net.util.IPAddressUtil;
47 import sun.net.spi.nameservice.*;
48
49 /**
50 * This class represents an Internet Protocol (IP) address.
51 *
52 * <p> An IP address is either a 32-bit or 128-bit unsigned number
53 * used by IP, a lower-level protocol on which protocols like UDP and
54 * TCP are built. The IP address architecture is defined by <a
55 * href="http://www.ietf.org/rfc/rfc790.txt"><i>RFC 790:
56 * Assigned Numbers</i></a>, <a
57 * href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC 1918:
58 * Address Allocation for Private Internets</i></a>, <a
59 * href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC 2365:
60 * Administratively Scoped IP Multicast</i></a>, and <a
61 * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC 2373: IP
62 * Version 6 Addressing Architecture</i></a>. An instance of an
63 * InetAddress consists of an IP address and possibly its
64 * corresponding host name (depending on whether it is constructed
65 * with a host name or whether it has already done reverse host name
66 * resolution).
67 *
68 * <h3> Address types </h3>
69 *
70 * <blockquote><table cellspacing=2 summary="Description of unicast and multicast address types">
71 * <tr><th valign=top><i>unicast</i></th>
72 * <td>An identifier for a single interface. A packet sent to
73 * a unicast address is delivered to the interface identified by
74 * that address.
75 *
76 * <p> The Unspecified Address -- Also called anylocal or wildcard
77 * address. It must never be assigned to any node. It indicates the
78 * absence of an address. One example of its use is as the target of
79 * bind, which allows a server to accept a client connection on any
80 * interface, in case the server host has multiple interfaces.
81 *
82 * <p> The <i>unspecified</i> address must not be used as
83 * the destination address of an IP packet.
84 *
85 * <p> The <i>Loopback</i> Addresses -- This is the address
86 * assigned to the loopback interface. Anything sent to this
87 * IP address loops around and becomes IP input on the local
88 * host. This address is often used when testing a
89 * client.</td></tr>
90 * <tr><th valign=top><i>multicast</i></th>
91 * <td>An identifier for a set of interfaces (typically belonging
92 * to different nodes). A packet sent to a multicast address is
93 * delivered to all interfaces identified by that address.</td></tr>
94 * </table></blockquote>
95 *
96 * <h4> IP address scope </h4>
97 *
98 * <p> <i>Link-local</i> addresses are designed to be used for addressing
99 * on a single link for purposes such as auto-address configuration,
100 * neighbor discovery, or when no routers are present.
101 *
102 * <p> <i>Site-local</i> addresses are designed to be used for addressing
103 * inside of a site without the need for a global prefix.
104 *
105 * <p> <i>Global</i> addresses are unique across the internet.
106 *
107 * <h4> Textual representation of IP addresses </h4>
108 *
109 * The textual representation of an IP address is address family specific.
110 *
111 * <p>
112 *
113 * For IPv4 address format, please refer to <A
114 * HREF="Inet4Address.html#format">Inet4Address#format</A>; For IPv6
115 * address format, please refer to <A
116 * HREF="Inet6Address.html#format">Inet6Address#format</A>.
117 *
118 * <P>There is a <a href="doc-files/net-properties.html#Ipv4IPv6">couple of
119 * System Properties</a> affecting how IPv4 and IPv6 addresses are used.</P>
120 *
121 * <h4> Host Name Resolution </h4>
122 *
123 * Host name-to-IP address <i>resolution</i> is accomplished through
124 * the use of a combination of local machine configuration information
125 * and network naming services such as the Domain Name System (DNS)
126 * and Network Information Service(NIS). The particular naming
127 * services(s) being used is by default the local machine configured
128 * one. For any host name, its corresponding IP address is returned.
129 *
130 * <p> <i>Reverse name resolution</i> means that for any IP address,
131 * the host associated with the IP address is returned.
132 *
133 * <p> The InetAddress class provides methods to resolve host names to
134 * their IP addresses and vice versa.
135 *
136 * <h4> InetAddress Caching </h4>
137 *
138 * The InetAddress class has a cache to store successful as well as
139 * unsuccessful host name resolutions.
140 *
141 * <p> By default, when a security manager is installed, in order to
142 * protect against DNS spoofing attacks,
143 * the result of positive host name resolutions are
144 * cached forever. When a security manager is not installed, the default
145 * behavior is to cache entries for a finite (implementation dependent)
146 * period of time. The result of unsuccessful host
147 * name resolution is cached for a very short period of time (10
148 * seconds) to improve performance.
149 *
150 * <p> If the default behavior is not desired, then a Java security property
151 * can be set to a different Time-to-live (TTL) value for positive
152 * caching. Likewise, a system admin can configure a different
153 * negative caching TTL value when needed.
154 *
155 * <p> Two Java security properties control the TTL values used for
156 * positive and negative host name resolution caching:
157 *
158 * <blockquote>
159 * <dl>
160 * <dt><b>networkaddress.cache.ttl</b></dt>
161 * <dd>Indicates the caching policy for successful name lookups from
162 * the name service. The value is specified as an integer to indicate
163 * the number of seconds to cache the successful lookup. The default
164 * setting is to cache for an implementation specific period of time.
165 * <p>
166 * A value of -1 indicates "cache forever".
167 * </dd>
168 * <dt><b>networkaddress.cache.negative.ttl</b> (default: 10)</dt>
169 * <dd>Indicates the caching policy for un-successful name lookups
170 * from the name service. The value is specified as an integer to
171 * indicate the number of seconds to cache the failure for
172 * un-successful lookups.
173 * <p>
174 * A value of 0 indicates "never cache".
175 * A value of -1 indicates "cache forever".
176 * </dd>
177 * </dl>
178 * </blockquote>
179 *
180 * @author Chris Warth
181 * @see java.net.InetAddress#getByAddress(byte[])
182 * @see java.net.InetAddress#getByAddress(java.lang.String, byte[])
183 * @see java.net.InetAddress#getAllByName(java.lang.String)
184 * @see java.net.InetAddress#getByName(java.lang.String)
185 * @see java.net.InetAddress#getLocalHost()
186 * @since JDK1.0
187 */
188 public
189 class InetAddress implements java.io.Serializable {
190 /**
191 * Specify the address family: Internet Protocol, Version 4
192 * @since 1.4
193 */
194 static final int IPv4 = 1;
195
196 /**
197 * Specify the address family: Internet Protocol, Version 6
198 * @since 1.4
199 */
200 static final int IPv6 = 2;
201
202 /* Specify address family preference */
203 static transient boolean preferIPv6Address = false;
204
205 static class InetAddressHolder {
206
207 InetAddressHolder() {}
208
209 InetAddressHolder(String hostName, int address, int family) {
210 this.hostName = hostName;
211 this.address = address;
212 this.family = family;
213 }
214
215 void init(String hostName, int family) {
216 this.hostName = hostName;
217 if (family != -1) {
218 this.family = family;
219 }
220 }
221
222 String hostName;
223
224 String getHostName() {
225 return hostName;
226 }
227
228 /**
229 * Holds a 32-bit IPv4 address.
230 */
231 int address;
232
233 int getAddress() {
234 return address;
235 }
236
237 /**
238 * Specifies the address family type, for instance, '1' for IPv4
239 * addresses, and '2' for IPv6 addresses.
240 */
241 int family;
242
243 int getFamily() {
244 return family;
245 }
246 }
247
248 /* Used to store the serializable fields of InetAddress */
249 final transient InetAddressHolder holder;
250
251 InetAddressHolder holder() {
252 return holder;
253 }
254
255 /* Used to store the name service provider */
256 private static List<NameService> nameServices = null;
257
258 /* Used to store the best available hostname */
259 private transient String canonicalHostName = null;
260
261 /** use serialVersionUID from JDK 1.0.2 for interoperability */
262 private static final long serialVersionUID = 3286316764910316507L;
263
264 /*
265 * Load net library into runtime, and perform initializations.
266 */
267 static {
268 preferIPv6Address = java.security.AccessController.doPrivileged(
269 new GetBooleanAction("java.net.preferIPv6Addresses")).booleanValue();
270 AccessController.doPrivileged(
271 new java.security.PrivilegedAction<Void>() {
272 public Void run() {
273 System.loadLibrary("net");
274 return null;
275 }
276 });
277 init();
278 }
279
280 /**
281 * Constructor for the Socket.accept() method.
282 * This creates an empty InetAddress, which is filled in by
283 * the accept() method. This InetAddress, however, is not
284 * put in the address cache, since it is not created by name.
285 */
286 InetAddress() {
287 holder = new InetAddressHolder();
288 }
289
290 /**
291 * Replaces the de-serialized object with an Inet4Address object.
292 *
293 * @return the alternate object to the de-serialized object.
294 *
295 * @throws ObjectStreamException if a new object replacing this
296 * object could not be created
297 */
298 private Object readResolve() throws ObjectStreamException {
299 // will replace the deserialized 'this' object
300 return new Inet4Address(holder().getHostName(), holder().getAddress());
301 }
302
303 /**
304 * Utility routine to check if the InetAddress is an
305 * IP multicast address.
306 * @return a {@code boolean} indicating if the InetAddress is
307 * an IP multicast address
308 * @since JDK1.1
309 */
310 public boolean isMulticastAddress() {
311 return false;
312 }
313
314 /**
315 * Utility routine to check if the InetAddress in a wildcard address.
316 * @return a {@code boolean} indicating if the Inetaddress is
317 * a wildcard address.
318 * @since 1.4
319 */
320 public boolean isAnyLocalAddress() {
321 return false;
322 }
323
324 /**
325 * Utility routine to check if the InetAddress is a loopback address.
326 *
327 * @return a {@code boolean} indicating if the InetAddress is
328 * a loopback address; or false otherwise.
329 * @since 1.4
330 */
331 public boolean isLoopbackAddress() {
332 return false;
333 }
334
335 /**
336 * Utility routine to check if the InetAddress is an link local address.
337 *
338 * @return a {@code boolean} indicating if the InetAddress is
339 * a link local address; or false if address is not a link local unicast address.
340 * @since 1.4
341 */
342 public boolean isLinkLocalAddress() {
343 return false;
344 }
345
346 /**
347 * Utility routine to check if the InetAddress is a site local address.
348 *
349 * @return a {@code boolean} indicating if the InetAddress is
350 * a site local address; or false if address is not a site local unicast address.
351 * @since 1.4
352 */
353 public boolean isSiteLocalAddress() {
354 return false;
355 }
356
357 /**
358 * Utility routine to check if the multicast address has global scope.
359 *
360 * @return a {@code boolean} indicating if the address has
361 * is a multicast address of global scope, false if it is not
362 * of global scope or it is not a multicast address
363 * @since 1.4
364 */
365 public boolean isMCGlobal() {
366 return false;
367 }
368
369 /**
370 * Utility routine to check if the multicast address has node scope.
371 *
372 * @return a {@code boolean} indicating if the address has
373 * is a multicast address of node-local scope, false if it is not
374 * of node-local scope or it is not a multicast address
375 * @since 1.4
376 */
377 public boolean isMCNodeLocal() {
378 return false;
379 }
380
381 /**
382 * Utility routine to check if the multicast address has link scope.
383 *
384 * @return a {@code boolean} indicating if the address has
385 * is a multicast address of link-local scope, false if it is not
386 * of link-local scope or it is not a multicast address
387 * @since 1.4
388 */
389 public boolean isMCLinkLocal() {
390 return false;
391 }
392
393 /**
394 * Utility routine to check if the multicast address has site scope.
395 *
396 * @return a {@code boolean} indicating if the address has
397 * is a multicast address of site-local scope, false if it is not
398 * of site-local scope or it is not a multicast address
399 * @since 1.4
400 */
401 public boolean isMCSiteLocal() {
402 return false;
403 }
404
405 /**
406 * Utility routine to check if the multicast address has organization scope.
407 *
408 * @return a {@code boolean} indicating if the address has
409 * is a multicast address of organization-local scope,
410 * false if it is not of organization-local scope
411 * or it is not a multicast address
412 * @since 1.4
413 */
414 public boolean isMCOrgLocal() {
415 return false;
416 }
417
418
419 /**
420 * Test whether that address is reachable. Best effort is made by the
421 * implementation to try to reach the host, but firewalls and server
422 * configuration may block requests resulting in a unreachable status
423 * while some specific ports may be accessible.
424 * A typical implementation will use ICMP ECHO REQUESTs if the
425 * privilege can be obtained, otherwise it will try to establish
426 * a TCP connection on port 7 (Echo) of the destination host.
427 * <p>
428 * The timeout value, in milliseconds, indicates the maximum amount of time
429 * the try should take. If the operation times out before getting an
430 * answer, the host is deemed unreachable. A negative value will result
431 * in an IllegalArgumentException being thrown.
432 *
433 * @param timeout the time, in milliseconds, before the call aborts
434 * @return a {@code boolean} indicating if the address is reachable.
435 * @throws IOException if a network error occurs
436 * @throws IllegalArgumentException if {@code timeout} is negative.
437 * @since 1.5
438 */
439 public boolean isReachable(int timeout) throws IOException {
440 return isReachable(null, 0 , timeout);
441 }
442
443 /**
444 * Test whether that address is reachable. Best effort is made by the
445 * implementation to try to reach the host, but firewalls and server
446 * configuration may block requests resulting in a unreachable status
447 * while some specific ports may be accessible.
448 * A typical implementation will use ICMP ECHO REQUESTs if the
449 * privilege can be obtained, otherwise it will try to establish
450 * a TCP connection on port 7 (Echo) of the destination host.
451 * <p>
452 * The {@code network interface} and {@code ttl} parameters
453 * let the caller specify which network interface the test will go through
454 * and the maximum number of hops the packets should go through.
455 * A negative value for the {@code ttl} will result in an
456 * IllegalArgumentException being thrown.
457 * <p>
458 * The timeout value, in milliseconds, indicates the maximum amount of time
459 * the try should take. If the operation times out before getting an
460 * answer, the host is deemed unreachable. A negative value will result
461 * in an IllegalArgumentException being thrown.
462 *
463 * @param netif the NetworkInterface through which the
464 * test will be done, or null for any interface
465 * @param ttl the maximum numbers of hops to try or 0 for the
466 * default
467 * @param timeout the time, in milliseconds, before the call aborts
468 * @throws IllegalArgumentException if either {@code timeout}
469 * or {@code ttl} are negative.
470 * @return a {@code boolean}indicating if the address is reachable.
471 * @throws IOException if a network error occurs
472 * @since 1.5
473 */
474 public boolean isReachable(NetworkInterface netif, int ttl,
475 int timeout) throws IOException {
476 if (ttl < 0)
477 throw new IllegalArgumentException("ttl can't be negative");
478 if (timeout < 0)
479 throw new IllegalArgumentException("timeout can't be negative");
480
481 return impl.isReachable(this, timeout, netif, ttl);
482 }
483
484 /**
485 * Gets the host name for this IP address.
486 *
487 * <p>If this InetAddress was created with a host name,
488 * this host name will be remembered and returned;
489 * otherwise, a reverse name lookup will be performed
490 * and the result will be returned based on the system
491 * configured name lookup service. If a lookup of the name service
492 * is required, call
493 * {@link #getCanonicalHostName() getCanonicalHostName}.
494 *
495 * <p>If there is a security manager, its
496 * {@code checkConnect} method is first called
497 * with the hostname and {@code -1}
498 * as its arguments to see if the operation is allowed.
499 * If the operation is not allowed, it will return
500 * the textual representation of the IP address.
501 *
502 * @return the host name for this IP address, or if the operation
503 * is not allowed by the security check, the textual
504 * representation of the IP address.
505 *
506 * @see InetAddress#getCanonicalHostName
507 * @see SecurityManager#checkConnect
508 */
509 public String getHostName() {
510 return getHostName(true);
511 }
512
513 /**
514 * Returns the hostname for this address.
515 * If the host is equal to null, then this address refers to any
516 * of the local machine's available network addresses.
517 * this is package private so SocketPermission can make calls into
518 * here without a security check.
519 *
520 * <p>If there is a security manager, this method first
521 * calls its {@code checkConnect} method
522 * with the hostname and {@code -1}
523 * as its arguments to see if the calling code is allowed to know
524 * the hostname for this IP address, i.e., to connect to the host.
525 * If the operation is not allowed, it will return
526 * the textual representation of the IP address.
527 *
528 * @return the host name for this IP address, or if the operation
529 * is not allowed by the security check, the textual
530 * representation of the IP address.
531 *
532 * @param check make security check if true
533 *
534 * @see SecurityManager#checkConnect
535 */
536 String getHostName(boolean check) {
537 if (holder().getHostName() == null) {
538 holder().hostName = InetAddress.getHostFromNameService(this, check);
539 }
540 return holder().getHostName();
541 }
542
543 /**
544 * Gets the fully qualified domain name for this IP address.
545 * Best effort method, meaning we may not be able to return
546 * the FQDN depending on the underlying system configuration.
547 *
548 * <p>If there is a security manager, this method first
549 * calls its {@code checkConnect} method
550 * with the hostname and {@code -1}
551 * as its arguments to see if the calling code is allowed to know
552 * the hostname for this IP address, i.e., to connect to the host.
553 * If the operation is not allowed, it will return
554 * the textual representation of the IP address.
555 *
556 * @return the fully qualified domain name for this IP address,
557 * or if the operation is not allowed by the security check,
558 * the textual representation of the IP address.
559 *
560 * @see SecurityManager#checkConnect
561 *
562 * @since 1.4
563 */
564 public String getCanonicalHostName() {
565 if (canonicalHostName == null) {
566 canonicalHostName =
567 InetAddress.getHostFromNameService(this, true);
568 }
569 return canonicalHostName;
570 }
571
572 /**
573 * Returns the hostname for this address.
574 *
575 * <p>If there is a security manager, this method first
576 * calls its {@code checkConnect} method
577 * with the hostname and {@code -1}
578 * as its arguments to see if the calling code is allowed to know
579 * the hostname for this IP address, i.e., to connect to the host.
580 * If the operation is not allowed, it will return
581 * the textual representation of the IP address.
582 *
583 * @return the host name for this IP address, or if the operation
584 * is not allowed by the security check, the textual
585 * representation of the IP address.
586 *
587 * @param check make security check if true
588 *
589 * @see SecurityManager#checkConnect
590 */
591 private static String getHostFromNameService(InetAddress addr, boolean check) {
592 String host = null;
593 for (NameService nameService : nameServices) {
594 try {
595 // first lookup the hostname
596 host = nameService.getHostByAddr(addr.getAddress());
597
598 /* check to see if calling code is allowed to know
599 * the hostname for this IP address, ie, connect to the host
600 */
601 if (check) {
602 SecurityManager sec = System.getSecurityManager();
603 if (sec != null) {
604 sec.checkConnect(host, -1);
605 }
606 }
607
608 /* now get all the IP addresses for this hostname,
609 * and make sure one of them matches the original IP
610 * address. We do this to try and prevent spoofing.
611 */
612
613 InetAddress[] arr = InetAddress.getAllByName0(host, check);
614 boolean ok = false;
615
616 if(arr != null) {
617 for(int i = 0; !ok && i < arr.length; i++) {
618 ok = addr.equals(arr[i]);
619 }
620 }
621
622 //XXX: if it looks a spoof just return the address?
623 if (!ok) {
624 host = addr.getHostAddress();
625 return host;
626 }
627
628 break;
629
630 } catch (SecurityException e) {
631 host = addr.getHostAddress();
632 break;
633 } catch (UnknownHostException e) {
634 host = addr.getHostAddress();
635 // let next provider resolve the hostname
636 }
637 }
638
639 return host;
640 }
641
642 /**
643 * Returns the raw IP address of this {@code InetAddress}
644 * object. The result is in network byte order: the highest order
645 * byte of the address is in {@code getAddress()[0]}.
646 *
647 * @return the raw IP address of this object.
648 */
649 public byte[] getAddress() {
650 return null;
651 }
652
653 /**
654 * Returns the IP address string in textual presentation.
655 *
656 * @return the raw IP address in a string format.
657 * @since JDK1.0.2
658 */
659 public String getHostAddress() {
660 return null;
661 }
662
663 /**
664 * Returns a hashcode for this IP address.
665 *
666 * @return a hash code value for this IP address.
667 */
668 public int hashCode() {
669 return -1;
670 }
671
672 /**
673 * Compares this object against the specified object.
674 * The result is {@code true} if and only if the argument is
675 * not {@code null} and it represents the same IP address as
676 * this object.
677 * <p>
678 * Two instances of {@code InetAddress} represent the same IP
679 * address if the length of the byte arrays returned by
680 * {@code getAddress} is the same for both, and each of the
681 * array components is the same for the byte arrays.
682 *
683 * @param obj the object to compare against.
684 * @return {@code true} if the objects are the same;
685 * {@code false} otherwise.
686 * @see java.net.InetAddress#getAddress()
687 */
688 public boolean equals(Object obj) {
689 return false;
690 }
691
692 /**
693 * Converts this IP address to a {@code String}. The
694 * string returned is of the form: hostname / literal IP
695 * address.
696 *
697 * If the host name is unresolved, no reverse name service lookup
698 * is performed. The hostname part will be represented by an empty string.
699 *
700 * @return a string representation of this IP address.
701 */
702 public String toString() {
703 String hostName = holder().getHostName();
704 return ((hostName != null) ? hostName : "")
705 + "/" + getHostAddress();
706 }
707
708 /*
709 * Cached addresses - our own litle nis, not!
710 */
711 private static Cache addressCache = new Cache(Cache.Type.Positive);
712
713 private static Cache negativeCache = new Cache(Cache.Type.Negative);
714
715 private static boolean addressCacheInit = false;
716
717 static InetAddress[] unknown_array; // put THIS in cache
718
719 static InetAddressImpl impl;
720
721 private static final HashMap<String, Void> lookupTable = new HashMap<>();
722
723 /**
724 * Represents a cache entry
725 */
726 static final class CacheEntry {
727
728 CacheEntry(InetAddress[] addresses, long expiration) {
729 this.addresses = addresses;
730 this.expiration = expiration;
731 }
732
733 InetAddress[] addresses;
734 long expiration;
735 }
736
737 /**
738 * A cache that manages entries based on a policy specified
739 * at creation time.
740 */
741 static final class Cache {
742 private LinkedHashMap<String, CacheEntry> cache;
743 private Type type;
744
745 enum Type {Positive, Negative};
746
747 /**
748 * Create cache
749 */
750 public Cache(Type type) {
751 this.type = type;
752 cache = new LinkedHashMap<String, CacheEntry>();
753 }
754
755 private int getPolicy() {
756 if (type == Type.Positive) {
757 return InetAddressCachePolicy.get();
758 } else {
759 return InetAddressCachePolicy.getNegative();
760 }
761 }
762
763 /**
764 * Add an entry to the cache. If there's already an
765 * entry then for this host then the entry will be
766 * replaced.
767 */
768 public Cache put(String host, InetAddress[] addresses) {
769 int policy = getPolicy();
770 if (policy == InetAddressCachePolicy.NEVER) {
771 return this;
772 }
773
774 // purge any expired entries
775
776 if (policy != InetAddressCachePolicy.FOREVER) {
777
778 // As we iterate in insertion order we can
779 // terminate when a non-expired entry is found.
780 LinkedList<String> expired = new LinkedList<>();
781 long now = System.currentTimeMillis();
782 for (String key : cache.keySet()) {
783 CacheEntry entry = cache.get(key);
784
785 if (entry.expiration >= 0 && entry.expiration < now) {
786 expired.add(key);
787 } else {
788 break;
789 }
790 }
791
792 for (String key : expired) {
793 cache.remove(key);
794 }
795 }
796
797 // create new entry and add it to the cache
798 // -- as a HashMap replaces existing entries we
799 // don't need to explicitly check if there is
800 // already an entry for this host.
801 long expiration;
802 if (policy == InetAddressCachePolicy.FOREVER) {
803 expiration = -1;
804 } else {
805 expiration = System.currentTimeMillis() + (policy * 1000);
806 }
807 CacheEntry entry = new CacheEntry(addresses, expiration);
808 cache.put(host, entry);
809 return this;
810 }
811
812 /**
813 * Query the cache for the specific host. If found then
814 * return its CacheEntry, or null if not found.
815 */
816 public CacheEntry get(String host) {
817 int policy = getPolicy();
818 if (policy == InetAddressCachePolicy.NEVER) {
819 return null;
820 }
821 CacheEntry entry = cache.get(host);
822
823 // check if entry has expired
824 if (entry != null && policy != InetAddressCachePolicy.FOREVER) {
825 if (entry.expiration >= 0 &&
826 entry.expiration < System.currentTimeMillis()) {
827 cache.remove(host);
828 entry = null;
829 }
830 }
831
832 return entry;
833 }
834 }
835
836 /*
837 * Initialize cache and insert anyLocalAddress into the
838 * unknown array with no expiry.
839 */
840 private static void cacheInitIfNeeded() {
841 assert Thread.holdsLock(addressCache);
842 if (addressCacheInit) {
843 return;
844 }
845 unknown_array = new InetAddress[1];
846 unknown_array[0] = impl.anyLocalAddress();
847
848 addressCache.put(impl.anyLocalAddress().getHostName(),
849 unknown_array);
850
851 addressCacheInit = true;
852 }
853
854 /*
855 * Cache the given hostname and addresses.
856 */
857 private static void cacheAddresses(String hostname,
858 InetAddress[] addresses,
859 boolean success) {
860 hostname = hostname.toLowerCase();
861 synchronized (addressCache) {
862 cacheInitIfNeeded();
863 if (success) {
864 addressCache.put(hostname, addresses);
865 } else {
866 negativeCache.put(hostname, addresses);
867 }
868 }
869 }
870
871 /*
872 * Lookup hostname in cache (positive & negative cache). If
873 * found return addresses, null if not found.
874 */
875 private static InetAddress[] getCachedAddresses(String hostname) {
876 hostname = hostname.toLowerCase();
877
878 // search both positive & negative caches
879
880 synchronized (addressCache) {
881 cacheInitIfNeeded();
882
883 CacheEntry entry = addressCache.get(hostname);
884 if (entry == null) {
885 entry = negativeCache.get(hostname);
886 }
887
888 if (entry != null) {
889 return entry.addresses;
890 }
891 }
892
893 // not found
894 return null;
895 }
896
897 private static NameService createNSProvider(String provider) {
898 if (provider == null)
899 return null;
900
901 NameService nameService = null;
902 if (provider.equals("default")) {
903 // initialize the default name service
904 nameService = new NameService() {
905 public InetAddress[] lookupAllHostAddr(String host)
906 throws UnknownHostException {
907 return impl.lookupAllHostAddr(host);
908 }
909 public String getHostByAddr(byte[] addr)
910 throws UnknownHostException {
911 return impl.getHostByAddr(addr);
912 }
913 };
914 } else {
915 final String providerName = provider;
916 try {
917 nameService = java.security.AccessController.doPrivileged(
918 new java.security.PrivilegedExceptionAction<NameService>() {
919 public NameService run() {
920 Iterator<NameServiceDescriptor> itr =
921 ServiceLoader.load(NameServiceDescriptor.class)
922 .iterator();
923 while (itr.hasNext()) {
924 NameServiceDescriptor nsd = itr.next();
925 if (providerName.
926 equalsIgnoreCase(nsd.getType()+","
927 +nsd.getProviderName())) {
928 try {
929 return nsd.createNameService();
930 } catch (Exception e) {
931 e.printStackTrace();
932 System.err.println(
933 "Cannot create name service:"
934 +providerName+": " + e);
935 }
936 }
937 }
938
939 return null;
940 }
941 }
942 );
943 } catch (java.security.PrivilegedActionException e) {
944 }
945 }
946
947 return nameService;
948 }
949
950 static {
951 // create the impl
952 impl = InetAddressImplFactory.create();
953
954 // get name service if provided and requested
955 String provider = null;;
956 String propPrefix = "sun.net.spi.nameservice.provider.";
957 int n = 1;
958 nameServices = new ArrayList<NameService>();
959 provider = AccessController.doPrivileged(
960 new GetPropertyAction(propPrefix + n));
961 while (provider != null) {
962 NameService ns = createNSProvider(provider);
963 if (ns != null)
964 nameServices.add(ns);
965
966 n++;
967 provider = AccessController.doPrivileged(
968 new GetPropertyAction(propPrefix + n));
969 }
970
971 // if not designate any name services provider,
972 // create a default one
973 if (nameServices.size() == 0) {
974 NameService ns = createNSProvider("default");
975 nameServices.add(ns);
976 }
977 }
978
979 /**
980 * Creates an InetAddress based on the provided host name and IP address.
981 * No name service is checked for the validity of the address.
982 *
983 * <p> The host name can either be a machine name, such as
984 * "{@code java.sun.com}", or a textual representation of its IP
985 * address.
986 * <p> No validity checking is done on the host name either.
987 *
988 * <p> If addr specifies an IPv4 address an instance of Inet4Address
989 * will be returned; otherwise, an instance of Inet6Address
990 * will be returned.
991 *
992 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
993 * must be 16 bytes long
994 *
995 * @param host the specified host
996 * @param addr the raw IP address in network byte order
997 * @return an InetAddress object created from the raw IP address.
998 * @exception UnknownHostException if IP address is of illegal length
999 * @since 1.4
1000 */
1001 public static InetAddress getByAddress(String host, byte[] addr)
1002 throws UnknownHostException {
1003 if (host != null && host.length() > 0 && host.charAt(0) == '[') {
1004 if (host.charAt(host.length()-1) == ']') {
1005 host = host.substring(1, host.length() -1);
1006 }
1007 }
1008 if (addr != null) {
1009 if (addr.length == Inet4Address.INADDRSZ) {
1010 return new Inet4Address(host, addr);
1011 } else if (addr.length == Inet6Address.INADDRSZ) {
1012 byte[] newAddr
1013 = IPAddressUtil.convertFromIPv4MappedAddress(addr);
1014 if (newAddr != null) {
1015 return new Inet4Address(host, newAddr);
1016 } else {
1017 return new Inet6Address(host, addr);
1018 }
1019 }
1020 }
1021 throw new UnknownHostException("addr is of illegal length");
1022 }
1023
1024
1025 /**
1026 * Determines the IP address of a host, given the host's name.
1027 *
1028 * <p> The host name can either be a machine name, such as
1029 * "{@code java.sun.com}", or a textual representation of its
1030 * IP address. If a literal IP address is supplied, only the
1031 * validity of the address format is checked.
1032 *
1033 * <p> For {@code host} specified in literal IPv6 address,
1034 * either the form defined in RFC 2732 or the literal IPv6 address
1035 * format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
1036 * supported. See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
1037 * scoped addresses.
1038 *
1039 * <p> If the host is {@code null} then an {@code InetAddress}
1040 * representing an address of the loopback interface is returned.
1041 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1042 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1043 * section 2.5.3. </p>
1044 *
1045 * @param host the specified host, or {@code null}.
1046 * @return an IP address for the given host name.
1047 * @exception UnknownHostException if no IP address for the
1048 * {@code host} could be found, or if a scope_id was specified
1049 * for a global IPv6 address.
1050 * @exception SecurityException if a security manager exists
1051 * and its checkConnect method doesn't allow the operation
1052 */
1053 public static InetAddress getByName(String host)
1054 throws UnknownHostException {
1055 return InetAddress.getAllByName(host)[0];
1056 }
1057
1058 // called from deployment cache manager
1059 private static InetAddress getByName(String host, InetAddress reqAddr)
1060 throws UnknownHostException {
1061 return InetAddress.getAllByName(host, reqAddr)[0];
1062 }
1063
1064 /**
1065 * Given the name of a host, returns an array of its IP addresses,
1066 * based on the configured name service on the system.
1067 *
1068 * <p> The host name can either be a machine name, such as
1069 * "{@code java.sun.com}", or a textual representation of its IP
1070 * address. If a literal IP address is supplied, only the
1071 * validity of the address format is checked.
1072 *
1073 * <p> For {@code host} specified in <i>literal IPv6 address</i>,
1074 * either the form defined in RFC 2732 or the literal IPv6 address
1075 * format defined in RFC 2373 is accepted. A literal IPv6 address may
1076 * also be qualified by appending a scoped zone identifier or scope_id.
1077 * The syntax and usage of scope_ids is described
1078 * <a href="Inet6Address.html#scoped">here</a>.
1079 * <p> If the host is {@code null} then an {@code InetAddress}
1080 * representing an address of the loopback interface is returned.
1081 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1082 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1083 * section 2.5.3. </p>
1084 *
1085 * <p> If there is a security manager and {@code host} is not
1086 * null and {@code host.length() } is not equal to zero, the
1087 * security manager's
1088 * {@code checkConnect} method is called
1089 * with the hostname and {@code -1}
1090 * as its arguments to see if the operation is allowed.
1091 *
1092 * @param host the name of the host, or {@code null}.
1093 * @return an array of all the IP addresses for a given host name.
1094 *
1095 * @exception UnknownHostException if no IP address for the
1096 * {@code host} could be found, or if a scope_id was specified
1097 * for a global IPv6 address.
1098 * @exception SecurityException if a security manager exists and its
1099 * {@code checkConnect} method doesn't allow the operation.
1100 *
1101 * @see SecurityManager#checkConnect
1102 */
1103 public static InetAddress[] getAllByName(String host)
1104 throws UnknownHostException {
1105 return getAllByName(host, null);
1106 }
1107
1108 private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
1109 throws UnknownHostException {
1110
1111 if (host == null || host.length() == 0) {
1112 InetAddress[] ret = new InetAddress[1];
1113 ret[0] = impl.loopbackAddress();
1114 return ret;
1115 }
1116
1117 boolean ipv6Expected = false;
1118 if (host.charAt(0) == '[') {
1119 // This is supposed to be an IPv6 literal
1120 if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1121 host = host.substring(1, host.length() -1);
1122 ipv6Expected = true;
1123 } else {
1124 // This was supposed to be a IPv6 address, but it's not!
1125 throw new UnknownHostException(host + ": invalid IPv6 address");
1126 }
1127 }
1128
1129 // if host is an IP address, we won't do further lookup
1130 if (Character.digit(host.charAt(0), 16) != -1
1131 || (host.charAt(0) == ':')) {
1132 byte[] addr = null;
1133 int numericZone = -1;
1134 String ifname = null;
1135 // see if it is IPv4 address
1136 addr = IPAddressUtil.textToNumericFormatV4(host);
1137 if (addr == null) {
1138 // This is supposed to be an IPv6 literal
1139 // Check if a numeric or string zone id is present
1140 int pos;
1141 if ((pos=host.indexOf ('%')) != -1) {
1142 numericZone = checkNumericZone (host);
1143 if (numericZone == -1) { /* remainder of string must be an ifname */
1144 ifname = host.substring (pos+1);
1145 }
1146 }
1147 if ((addr = IPAddressUtil.textToNumericFormatV6(host)) == null && host.contains(":")) {
1148 throw new UnknownHostException(host + ": invalid IPv6 address");
1149 }
1150 } else if (ipv6Expected) {
1151 // Means an IPv4 litteral between brackets!
1152 throw new UnknownHostException("["+host+"]");
1153 }
1154 InetAddress[] ret = new InetAddress[1];
1155 if(addr != null) {
1156 if (addr.length == Inet4Address.INADDRSZ) {
1157 ret[0] = new Inet4Address(null, addr);
1158 } else {
1159 if (ifname != null) {
1160 ret[0] = new Inet6Address(null, addr, ifname);
1161 } else {
1162 ret[0] = new Inet6Address(null, addr, numericZone);
1163 }
1164 }
1165 return ret;
1166 }
1167 } else if (ipv6Expected) {
1168 // We were expecting an IPv6 Litteral, but got something else
1169 throw new UnknownHostException("["+host+"]");
1170 }
1171 return getAllByName0(host, reqAddr, true);
1172 }
1173
1174 /**
1175 * Returns the loopback address.
1176 * <p>
1177 * The InetAddress returned will represent the IPv4
1178 * loopback address, 127.0.0.1, or the IPv6 loopback
1179 * address, ::1. The IPv4 loopback address returned
1180 * is only one of many in the form 127.*.*.*
1181 *
1182 * @return the InetAddress loopback instance.
1183 * @since 1.7
1184 */
1185 public static InetAddress getLoopbackAddress() {
1186 return impl.loopbackAddress();
1187 }
1188
1189
1190 /**
1191 * check if the literal address string has %nn appended
1192 * returns -1 if not, or the numeric value otherwise.
1193 *
1194 * %nn may also be a string that represents the displayName of
1195 * a currently available NetworkInterface.
1196 */
1197 private static int checkNumericZone (String s) throws UnknownHostException {
1198 int percent = s.indexOf ('%');
1199 int slen = s.length();
1200 int digit, zone=0;
1201 if (percent == -1) {
1202 return -1;
1203 }
1204 for (int i=percent+1; i<slen; i++) {
1205 char c = s.charAt(i);
1206 if (c == ']') {
1207 if (i == percent+1) {
1208 /* empty per-cent field */
1209 return -1;
1210 }
1211 break;
1212 }
1213 if ((digit = Character.digit (c, 10)) < 0) {
1214 return -1;
1215 }
1216 zone = (zone * 10) + digit;
1217 }
1218 return zone;
1219 }
1220
1221 private static InetAddress[] getAllByName0 (String host)
1222 throws UnknownHostException
1223 {
1224 return getAllByName0(host, true);
1225 }
1226
1227 /**
1228 * package private so SocketPermission can call it
1229 */
1230 static InetAddress[] getAllByName0 (String host, boolean check)
1231 throws UnknownHostException {
1232 return getAllByName0 (host, null, check);
1233 }
1234
1235 private static InetAddress[] getAllByName0 (String host, InetAddress reqAddr, boolean check)
1236 throws UnknownHostException {
1237
1238 /* If it gets here it is presumed to be a hostname */
1239 /* Cache.get can return: null, unknownAddress, or InetAddress[] */
1240
1241 /* make sure the connection to the host is allowed, before we
1242 * give out a hostname
1243 */
1244 if (check) {
1245 SecurityManager security = System.getSecurityManager();
1246 if (security != null) {
1247 security.checkConnect(host, -1);
1248 }
1249 }
1250
1251 InetAddress[] addresses = getCachedAddresses(host);
1252
1253 /* If no entry in cache, then do the host lookup */
1254 if (addresses == null) {
1255 addresses = getAddressesFromNameService(host, reqAddr);
1256 }
1257
1258 if (addresses == unknown_array)
1259 throw new UnknownHostException(host);
1260
1261 return addresses.clone();
1262 }
1263
1264 private static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
1265 throws UnknownHostException
1266 {
1267 InetAddress[] addresses = null;
1268 boolean success = false;
1269 UnknownHostException ex = null;
1270
1271 // Check whether the host is in the lookupTable.
1272 // 1) If the host isn't in the lookupTable when
1273 // checkLookupTable() is called, checkLookupTable()
1274 // would add the host in the lookupTable and
1275 // return null. So we will do the lookup.
1276 // 2) If the host is in the lookupTable when
1277 // checkLookupTable() is called, the current thread
1278 // would be blocked until the host is removed
1279 // from the lookupTable. Then this thread
1280 // should try to look up the addressCache.
1281 // i) if it found the addresses in the
1282 // addressCache, checkLookupTable() would
1283 // return the addresses.
1284 // ii) if it didn't find the addresses in the
1285 // addressCache for any reason,
1286 // it should add the host in the
1287 // lookupTable and return null so the
1288 // following code would do a lookup itself.
1289 if ((addresses = checkLookupTable(host)) == null) {
1290 try {
1291 // This is the first thread which looks up the addresses
1292 // this host or the cache entry for this host has been
1293 // expired so this thread should do the lookup.
1294 for (NameService nameService : nameServices) {
1295 try {
1296 /*
1297 * Do not put the call to lookup() inside the
1298 * constructor. if you do you will still be
1299 * allocating space when the lookup fails.
1300 */
1301
1302 addresses = nameService.lookupAllHostAddr(host);
1303 success = true;
1304 break;
1305 } catch (UnknownHostException uhe) {
1306 if (host.equalsIgnoreCase("localhost")) {
1307 InetAddress[] local = new InetAddress[] { impl.loopbackAddress() };
1308 addresses = local;
1309 success = true;
1310 break;
1311 }
1312 else {
1313 addresses = unknown_array;
1314 success = false;
1315 ex = uhe;
1316 }
1317 }
1318 }
1319
1320 // More to do?
1321 if (reqAddr != null && addresses.length > 1 && !addresses[0].equals(reqAddr)) {
1322 // Find it?
1323 int i = 1;
1324 for (; i < addresses.length; i++) {
1325 if (addresses[i].equals(reqAddr)) {
1326 break;
1327 }
1328 }
1329 // Rotate
1330 if (i < addresses.length) {
1331 InetAddress tmp, tmp2 = reqAddr;
1332 for (int j = 0; j < i; j++) {
1333 tmp = addresses[j];
1334 addresses[j] = tmp2;
1335 tmp2 = tmp;
1336 }
1337 addresses[i] = tmp2;
1338 }
1339 }
1340 // Cache the address.
1341 cacheAddresses(host, addresses, success);
1342
1343 if (!success && ex != null)
1344 throw ex;
1345
1346 } finally {
1347 // Delete host from the lookupTable and notify
1348 // all threads waiting on the lookupTable monitor.
1349 updateLookupTable(host);
1350 }
1351 }
1352
1353 return addresses;
1354 }
1355
1356
1357 private static InetAddress[] checkLookupTable(String host) {
1358 synchronized (lookupTable) {
1359 // If the host isn't in the lookupTable, add it in the
1360 // lookuptable and return null. The caller should do
1361 // the lookup.
1362 if (lookupTable.containsKey(host) == false) {
1363 lookupTable.put(host, null);
1364 return null;
1365 }
1366
1367 // If the host is in the lookupTable, it means that another
1368 // thread is trying to look up the addresses of this host.
1369 // This thread should wait.
1370 while (lookupTable.containsKey(host)) {
1371 try {
1372 lookupTable.wait();
1373 } catch (InterruptedException e) {
1374 }
1375 }
1376 }
1377
1378 // The other thread has finished looking up the addresses of
1379 // the host. This thread should retry to get the addresses
1380 // from the addressCache. If it doesn't get the addresses from
1381 // the cache, it will try to look up the addresses itself.
1382 InetAddress[] addresses = getCachedAddresses(host);
1383 if (addresses == null) {
1384 synchronized (lookupTable) {
1385 lookupTable.put(host, null);
1386 return null;
1387 }
1388 }
1389
1390 return addresses;
1391 }
1392
1393 private static void updateLookupTable(String host) {
1394 synchronized (lookupTable) {
1395 lookupTable.remove(host);
1396 lookupTable.notifyAll();
1397 }
1398 }
1399
1400 /**
1401 * Returns an {@code InetAddress} object given the raw IP address .
1402 * The argument is in network byte order: the highest order
1403 * byte of the address is in {@code getAddress()[0]}.
1404 *
1405 * <p> This method doesn't block, i.e. no reverse name service lookup
1406 * is performed.
1407 *
1408 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1409 * must be 16 bytes long
1410 *
1411 * @param addr the raw IP address in network byte order
1412 * @return an InetAddress object created from the raw IP address.
1413 * @exception UnknownHostException if IP address is of illegal length
1414 * @since 1.4
1415 */
1416 public static InetAddress getByAddress(byte[] addr)
1417 throws UnknownHostException {
1418 return getByAddress(null, addr);
1419 }
1420
1421 private static InetAddress cachedLocalHost = null;
1422 private static long cacheTime = 0;
1423 private static final long maxCacheTime = 5000L;
1424 private static final Object cacheLock = new Object();
1425
1426 /**
1427 * Returns the address of the local host. This is achieved by retrieving
1428 * the name of the host from the system, then resolving that name into
1429 * an {@code InetAddress}.
1430 *
1431 * <P>Note: The resolved address may be cached for a short period of time.
1432 * </P>
1433 *
1434 * <p>If there is a security manager, its
1435 * {@code checkConnect} method is called
1436 * with the local host name and {@code -1}
1437 * as its arguments to see if the operation is allowed.
1438 * If the operation is not allowed, an InetAddress representing
1439 * the loopback address is returned.
1440 *
1441 * @return the address of the local host.
1442 *
1443 * @exception UnknownHostException if the local host name could not
1444 * be resolved into an address.
1445 *
1446 * @see SecurityManager#checkConnect
1447 * @see java.net.InetAddress#getByName(java.lang.String)
1448 */
1449 public static InetAddress getLocalHost() throws UnknownHostException {
1450
1451 SecurityManager security = System.getSecurityManager();
1452 try {
1453 String local = impl.getLocalHostName();
1454
1455 if (security != null) {
1456 security.checkConnect(local, -1);
1457 }
1458
1459 if (local.equals("localhost")) {
1460 return impl.loopbackAddress();
1461 }
1462
1463 InetAddress ret = null;
1464 synchronized (cacheLock) {
1465 long now = System.currentTimeMillis();
1466 if (cachedLocalHost != null) {
1467 if ((now - cacheTime) < maxCacheTime) // Less than 5s old?
1468 ret = cachedLocalHost;
1469 else
1470 cachedLocalHost = null;
1471 }
1472
1473 // we are calling getAddressesFromNameService directly
1474 // to avoid getting localHost from cache
1475 if (ret == null) {
1476 InetAddress[] localAddrs;
1477 try {
1478 localAddrs =
1479 InetAddress.getAddressesFromNameService(local, null);
1480 } catch (UnknownHostException uhe) {
1481 // Rethrow with a more informative error message.
1482 UnknownHostException uhe2 =
1483 new UnknownHostException(local + ": " +
1484 uhe.getMessage());
1485 uhe2.initCause(uhe);
1486 throw uhe2;
1487 }
1488 cachedLocalHost = localAddrs[0];
1489 cacheTime = now;
1490 ret = localAddrs[0];
1491 }
1492 }
1493 return ret;
1494 } catch (java.lang.SecurityException e) {
1495 return impl.loopbackAddress();
1496 }
1497 }
1498
1499 /**
1500 * Perform class load-time initializations.
1501 */
1502 private static native void init();
1503
1504
1505 /*
1506 * Returns the InetAddress representing anyLocalAddress
1507 * (typically 0.0.0.0 or ::0)
1508 */
1509 static InetAddress anyLocalAddress() {
1510 return impl.anyLocalAddress();
1511 }
1512
1513 /*
1514 * Load and instantiate an underlying impl class
1515 */
1516 static InetAddressImpl loadImpl(String implName) {
1517 Object impl = null;
1518
1519 /*
1520 * Property "impl.prefix" will be prepended to the classname
1521 * of the implementation object we instantiate, to which we
1522 * delegate the real work (like native methods). This
1523 * property can vary across implementations of the java.
1524 * classes. The default is an empty String "".
1525 */
1526 String prefix = AccessController.doPrivileged(
1527 new GetPropertyAction("impl.prefix", ""));
1528 try {
1529 impl = Class.forName("java.net." + prefix + implName).newInstance();
1530 } catch (ClassNotFoundException e) {
1531 System.err.println("Class not found: java.net." + prefix +
1532 implName + ":\ncheck impl.prefix property " +
1533 "in your properties file.");
1534 } catch (InstantiationException e) {
1535 System.err.println("Could not instantiate: java.net." + prefix +
1536 implName + ":\ncheck impl.prefix property " +
1537 "in your properties file.");
1538 } catch (IllegalAccessException e) {
1539 System.err.println("Cannot access class: java.net." + prefix +
1540 implName + ":\ncheck impl.prefix property " +
1541 "in your properties file.");
1542 }
1543
1544 if (impl == null) {
1545 try {
1546 impl = Class.forName(implName).newInstance();
1547 } catch (Exception e) {
1548 throw new Error("System property impl.prefix incorrect");
1549 }
1550 }
1551
1552 return (InetAddressImpl) impl;
1553 }
1554
1555 private void readObjectNoData (ObjectInputStream s) throws
1556 IOException, ClassNotFoundException {
1557 if (getClass().getClassLoader() != null) {
1558 throw new SecurityException ("invalid address type");
1559 }
1560 }
1561
1562 private static final long FIELDS_OFFSET;
1563 private static final sun.misc.Unsafe UNSAFE;
1564
1565 static {
1566 try {
1567 sun.misc.Unsafe unsafe = sun.misc.Unsafe.getUnsafe();
1568 FIELDS_OFFSET = unsafe.objectFieldOffset(
1569 InetAddress.class.getDeclaredField("holder")
1570 );
1571 UNSAFE = unsafe;
1572 } catch (ReflectiveOperationException e) {
1573 throw new Error(e);
1574 }
1575 }
1576
1577 private void readObject (ObjectInputStream s) throws
1578 IOException, ClassNotFoundException {
1579 if (getClass().getClassLoader() != null) {
1580 throw new SecurityException ("invalid address type");
1581 }
1582 GetField gf = s.readFields();
1583 String host = (String)gf.get("hostName", null);
1584 int address= gf.get("address", 0);
1585 int family= gf.get("family", 0);
1586 InetAddressHolder h = new InetAddressHolder(host, address, family);
1587 UNSAFE.putObject(this, FIELDS_OFFSET, h);
1588 }
1589
1590 /* needed because the serializable fields no longer exist */
1591
1592 /**
1593 * @serialField hostName String
1594 * @serialField address int
1595 * @serialField family int
1596 */
1597 private static final ObjectStreamField[] serialPersistentFields = {
1598 new ObjectStreamField("hostName", String.class),
1599 new ObjectStreamField("address", int.class),
1600 new ObjectStreamField("family", int.class),
1601 };
1602
1603 private void writeObject (ObjectOutputStream s) throws
1604 IOException {
1605 if (getClass().getClassLoader() != null) {
1606 throw new SecurityException ("invalid address type");
1607 }
1608 PutField pf = s.putFields();
1609 pf.put("hostName", holder().getHostName());
1610 pf.put("address", holder().getAddress());
1611 pf.put("family", holder().getFamily());
1612 s.writeFields();
1613 }
1614 }
1615
1616 /*
1617 * Simple factory to create the impl
1618 */
1619 class InetAddressImplFactory {
1620
1621 static InetAddressImpl create() {
1622 return InetAddress.loadImpl(isIPv6Supported() ?
1623 "Inet6AddressImpl" : "Inet4AddressImpl");
1624 }
1625
1626 static native boolean isIPv6Supported();
1627 }