1 /*
2 * Copyright (c) 1995, 2015, Oracle and/or its affiliates. All rights reserved.
3 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
4 *
5 *
6 *
7 *
8 *
9 *
10 *
11 *
12 *
13 *
14 *
15 *
16 *
17 *
18 *
19 *
20 *
21 *
22 *
23 *
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 as 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 as 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 * Reserve the original application specified hostname.
208 *
209 * The original hostname is useful for domain-based endpoint
210 * identification (see RFC 2818 and RFC 6125). If an address
211 * was created with a raw IP address, a reverse name lookup
212 * may introduce endpoint identification security issue via
213 * DNS forging.
214 *
215 * Oracle JSSE provider is using this original hostname, via
216 * sun.misc.JavaNetAccess, for SSL/TLS endpoint identification.
217 *
218 * Note: May define a new public method in the future if necessary.
219 */
220 String originalHostName;
221
222 InetAddressHolder() {}
223
224 InetAddressHolder(String hostName, int address, int family) {
225 this.originalHostName = hostName;
226 this.hostName = hostName;
227 this.address = address;
228 this.family = family;
229 }
230
231 void init(String hostName, int family) {
232 this.originalHostName = hostName;
233 this.hostName = hostName;
234 if (family != -1) {
235 this.family = family;
236 }
237 }
238
239 String hostName;
240
241 String getHostName() {
242 return hostName;
243 }
244
245 String getOriginalHostName() {
246 return originalHostName;
247 }
248
249 /**
250 * Holds a 32-bit IPv4 address.
251 */
252 int address;
253
254 int getAddress() {
255 return address;
256 }
257
258 /**
259 * Specifies the address family type, for instance, '1' for IPv4
260 * addresses, and '2' for IPv6 addresses.
261 */
262 int family;
263
264 int getFamily() {
265 return family;
266 }
267 }
268
269 /* Used to store the serializable fields of InetAddress */
270 final transient InetAddressHolder holder;
271
272 InetAddressHolder holder() {
273 return holder;
274 }
275
276 /* Used to store the name service provider */
277 private static List<NameService> nameServices = null;
278
279 /* Used to store the best available hostname */
280 private transient String canonicalHostName = null;
281
282 /** use serialVersionUID from JDK 1.0.2 for interoperability */
283 private static final long serialVersionUID = 3286316764910316507L;
284
285 /*
286 * Load net library into runtime, and perform initializations.
287 */
288 static {
289 preferIPv6Address = java.security.AccessController.doPrivileged(
290 new GetBooleanAction("java.net.preferIPv6Addresses")).booleanValue();
291 AccessController.doPrivileged(
292 new java.security.PrivilegedAction<Void>() {
293 public Void run() {
294 System.loadLibrary("net");
295 return null;
296 }
297 });
298 init();
299 }
300
301 /**
302 * Constructor for the Socket.accept() method.
303 * This creates an empty InetAddress, which is filled in by
304 * the accept() method. This InetAddress, however, is not
305 * put in the address cache, since it is not created by name.
306 */
307 InetAddress() {
308 holder = new InetAddressHolder();
309 }
310
311 /**
312 * Replaces the de-serialized object with an Inet4Address object.
313 *
314 * @return the alternate object to the de-serialized object.
315 *
316 * @throws ObjectStreamException if a new object replacing this
317 * object could not be created
318 */
319 private Object readResolve() throws ObjectStreamException {
320 // will replace the deserialized 'this' object
321 return new Inet4Address(holder().getHostName(), holder().getAddress());
322 }
323
324 /**
325 * Utility routine to check if the InetAddress is an
326 * IP multicast address.
327 * @return a {@code boolean} indicating if the InetAddress is
328 * an IP multicast address
329 * @since JDK1.1
330 */
331 public boolean isMulticastAddress() {
332 return false;
333 }
334
335 /**
336 * Utility routine to check if the InetAddress in a wildcard address.
337 * @return a {@code boolean} indicating if the Inetaddress is
338 * a wildcard address.
339 * @since 1.4
340 */
341 public boolean isAnyLocalAddress() {
342 return false;
343 }
344
345 /**
346 * Utility routine to check if the InetAddress is a loopback address.
347 *
348 * @return a {@code boolean} indicating if the InetAddress is
349 * a loopback address; or false otherwise.
350 * @since 1.4
351 */
352 public boolean isLoopbackAddress() {
353 return false;
354 }
355
356 /**
357 * Utility routine to check if the InetAddress is an link local address.
358 *
359 * @return a {@code boolean} indicating if the InetAddress is
360 * a link local address; or false if address is not a link local unicast address.
361 * @since 1.4
362 */
363 public boolean isLinkLocalAddress() {
364 return false;
365 }
366
367 /**
368 * Utility routine to check if the InetAddress is a site local address.
369 *
370 * @return a {@code boolean} indicating if the InetAddress is
371 * a site local address; or false if address is not a site local unicast address.
372 * @since 1.4
373 */
374 public boolean isSiteLocalAddress() {
375 return false;
376 }
377
378 /**
379 * Utility routine to check if the multicast address has global scope.
380 *
381 * @return a {@code boolean} indicating if the address has
382 * is a multicast address of global scope, false if it is not
383 * of global scope or it is not a multicast address
384 * @since 1.4
385 */
386 public boolean isMCGlobal() {
387 return false;
388 }
389
390 /**
391 * Utility routine to check if the multicast address has node scope.
392 *
393 * @return a {@code boolean} indicating if the address has
394 * is a multicast address of node-local scope, false if it is not
395 * of node-local scope or it is not a multicast address
396 * @since 1.4
397 */
398 public boolean isMCNodeLocal() {
399 return false;
400 }
401
402 /**
403 * Utility routine to check if the multicast address has link scope.
404 *
405 * @return a {@code boolean} indicating if the address has
406 * is a multicast address of link-local scope, false if it is not
407 * of link-local scope or it is not a multicast address
408 * @since 1.4
409 */
410 public boolean isMCLinkLocal() {
411 return false;
412 }
413
414 /**
415 * Utility routine to check if the multicast address has site scope.
416 *
417 * @return a {@code boolean} indicating if the address has
418 * is a multicast address of site-local scope, false if it is not
419 * of site-local scope or it is not a multicast address
420 * @since 1.4
421 */
422 public boolean isMCSiteLocal() {
423 return false;
424 }
425
426 /**
427 * Utility routine to check if the multicast address has organization scope.
428 *
429 * @return a {@code boolean} indicating if the address has
430 * is a multicast address of organization-local scope,
431 * false if it is not of organization-local scope
432 * or it is not a multicast address
433 * @since 1.4
434 */
435 public boolean isMCOrgLocal() {
436 return false;
437 }
438
439
440 /**
441 * Test whether that address is reachable. Best effort is made by the
442 * implementation to try to reach the host, but firewalls and server
443 * configuration may block requests resulting in a unreachable status
444 * while some specific ports may be accessible.
445 * A typical implementation will use ICMP ECHO REQUESTs if the
446 * privilege can be obtained, otherwise it will try to establish
447 * a TCP connection on port 7 (Echo) of the destination host.
448 * <p>
449 * The timeout value, in milliseconds, indicates the maximum amount of time
450 * the try should take. If the operation times out before getting an
451 * answer, the host is deemed unreachable. A negative value will result
452 * in an IllegalArgumentException being thrown.
453 *
454 * @param timeout the time, in milliseconds, before the call aborts
455 * @return a {@code boolean} indicating if the address is reachable.
456 * @throws IOException if a network error occurs
457 * @throws IllegalArgumentException if {@code timeout} is negative.
458 * @since 1.5
459 */
460 public boolean isReachable(int timeout) throws IOException {
461 return isReachable(null, 0 , timeout);
462 }
463
464 /**
465 * Test whether that address is reachable. Best effort is made by the
466 * implementation to try to reach the host, but firewalls and server
467 * configuration may block requests resulting in a unreachable status
468 * while some specific ports may be accessible.
469 * A typical implementation will use ICMP ECHO REQUESTs if the
470 * privilege can be obtained, otherwise it will try to establish
471 * a TCP connection on port 7 (Echo) of the destination host.
472 * <p>
473 * The {@code network interface} and {@code ttl} parameters
474 * let the caller specify which network interface the test will go through
475 * and the maximum number of hops the packets should go through.
476 * A negative value for the {@code ttl} will result in an
477 * IllegalArgumentException being thrown.
478 * <p>
479 * The timeout value, in milliseconds, indicates the maximum amount of time
480 * the try should take. If the operation times out before getting an
481 * answer, the host is deemed unreachable. A negative value will result
482 * in an IllegalArgumentException being thrown.
483 *
484 * @param netif the NetworkInterface through which the
485 * test will be done, or null for any interface
486 * @param ttl the maximum numbers of hops to try or 0 for the
487 * default
488 * @param timeout the time, in milliseconds, before the call aborts
489 * @throws IllegalArgumentException if either {@code timeout}
490 * or {@code ttl} are negative.
491 * @return a {@code boolean}indicating if the address is reachable.
492 * @throws IOException if a network error occurs
493 * @since 1.5
494 */
495 public boolean isReachable(NetworkInterface netif, int ttl,
496 int timeout) throws IOException {
497 if (ttl < 0)
498 throw new IllegalArgumentException("ttl can't be negative");
499 if (timeout < 0)
500 throw new IllegalArgumentException("timeout can't be negative");
501
502 return impl.isReachable(this, timeout, netif, ttl);
503 }
504
505 /**
506 * Gets the host name for this IP address.
507 *
508 * <p>If this InetAddress was created with a host name,
509 * this host name will be remembered and returned;
510 * otherwise, a reverse name lookup will be performed
511 * and the result will be returned based on the system
512 * configured name lookup service. If a lookup of the name service
513 * is required, call
514 * {@link #getCanonicalHostName() getCanonicalHostName}.
515 *
516 * <p>If there is a security manager, its
517 * {@code checkConnect} method is first called
518 * with the hostname and {@code -1}
519 * as its arguments to see if the operation is allowed.
520 * If the operation is not allowed, it will return
521 * the textual representation of the IP address.
522 *
523 * @return the host name for this IP address, or if the operation
524 * is not allowed by the security check, the textual
525 * representation of the IP address.
526 *
527 * @see InetAddress#getCanonicalHostName
528 * @see SecurityManager#checkConnect
529 */
530 public String getHostName() {
531 return getHostName(true);
532 }
533
534 /**
535 * Returns the hostname for this address.
536 * If the host is equal to null, then this address refers to any
537 * of the local machine's available network addresses.
538 * this is package private so SocketPermission can make calls into
539 * here without a security check.
540 *
541 * <p>If there is a security manager, this method first
542 * calls its {@code checkConnect} method
543 * with the hostname and {@code -1}
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 String getHostName(boolean check) {
558 if (holder().getHostName() == null) {
559 holder().hostName = InetAddress.getHostFromNameService(this, check);
560 }
561 return holder().getHostName();
562 }
563
564 /**
565 * Gets the fully qualified domain name for this IP address.
566 * Best effort method, meaning we may not be able to return
567 * the FQDN depending on the underlying system configuration.
568 *
569 * <p>If there is a security manager, this method first
570 * calls its {@code checkConnect} method
571 * with the hostname and {@code -1}
572 * as its arguments to see if the calling code is allowed to know
573 * the hostname for this IP address, i.e., to connect to the host.
574 * If the operation is not allowed, it will return
575 * the textual representation of the IP address.
576 *
577 * @return the fully qualified domain name for this IP address,
578 * or if the operation is not allowed by the security check,
579 * the textual representation of the IP address.
580 *
581 * @see SecurityManager#checkConnect
582 *
583 * @since 1.4
584 */
585 public String getCanonicalHostName() {
586 if (canonicalHostName == null) {
587 canonicalHostName =
588 InetAddress.getHostFromNameService(this, true);
589 }
590 return canonicalHostName;
591 }
592
593 /**
594 * Returns the hostname for this address.
595 *
596 * <p>If there is a security manager, this method first
597 * calls its {@code checkConnect} method
598 * with the hostname and {@code -1}
599 * as its arguments to see if the calling code is allowed to know
600 * the hostname for this IP address, i.e., to connect to the host.
601 * If the operation is not allowed, it will return
602 * the textual representation of the IP address.
603 *
604 * @return the host name for this IP address, or if the operation
605 * is not allowed by the security check, the textual
606 * representation of the IP address.
607 *
608 * @param check make security check if true
609 *
610 * @see SecurityManager#checkConnect
611 */
612 private static String getHostFromNameService(InetAddress addr, boolean check) {
613 String host = null;
614 for (NameService nameService : nameServices) {
615 try {
616 // first lookup the hostname
617 host = nameService.getHostByAddr(addr.getAddress());
618
619 /* check to see if calling code is allowed to know
620 * the hostname for this IP address, ie, connect to the host
621 */
622 if (check) {
623 SecurityManager sec = System.getSecurityManager();
624 if (sec != null) {
625 sec.checkConnect(host, -1);
626 }
627 }
628
629 /* now get all the IP addresses for this hostname,
630 * and make sure one of them matches the original IP
631 * address. We do this to try and prevent spoofing.
632 */
633
634 InetAddress[] arr = InetAddress.getAllByName0(host, check);
635 boolean ok = false;
636
637 if(arr != null) {
638 for(int i = 0; !ok && i < arr.length; i++) {
639 ok = addr.equals(arr[i]);
640 }
641 }
642
643 //XXX: if it looks a spoof just return the address?
644 if (!ok) {
645 host = addr.getHostAddress();
646 return host;
647 }
648
649 break;
650
651 } catch (SecurityException e) {
652 host = addr.getHostAddress();
653 break;
654 } catch (UnknownHostException e) {
655 host = addr.getHostAddress();
656 // let next provider resolve the hostname
657 }
658 }
659
660 return host;
661 }
662
663 /**
664 * Returns the raw IP address of this {@code InetAddress}
665 * object. The result is in network byte order: the highest order
666 * byte of the address is in {@code getAddress()[0]}.
667 *
668 * @return the raw IP address of this object.
669 */
670 public byte[] getAddress() {
671 return null;
672 }
673
674 /**
675 * Returns the IP address string in textual presentation.
676 *
677 * @return the raw IP address in a string format.
678 * @since JDK1.0.2
679 */
680 public String getHostAddress() {
681 return null;
682 }
683
684 /**
685 * Returns a hashcode for this IP address.
686 *
687 * @return a hash code value for this IP address.
688 */
689 public int hashCode() {
690 return -1;
691 }
692
693 /**
694 * Compares this object against the specified object.
695 * The result is {@code true} if and only if the argument is
696 * not {@code null} and it represents the same IP address as
697 * this object.
698 * <p>
699 * Two instances of {@code InetAddress} represent the same IP
700 * address if the length of the byte arrays returned by
701 * {@code getAddress} is the same for both, and each of the
702 * array components is the same for the byte arrays.
703 *
704 * @param obj the object to compare against.
705 * @return {@code true} if the objects are the same;
706 * {@code false} otherwise.
707 * @see java.net.InetAddress#getAddress()
708 */
709 public boolean equals(Object obj) {
710 return false;
711 }
712
713 /**
714 * Converts this IP address to a {@code String}. The
715 * string returned is of the form: hostname / literal IP
716 * address.
717 *
718 * If the host name is unresolved, no reverse name service lookup
719 * is performed. The hostname part will be represented by an empty string.
720 *
721 * @return a string representation of this IP address.
722 */
723 public String toString() {
724 String hostName = holder().getHostName();
725 return ((hostName != null) ? hostName : "")
726 + "/" + getHostAddress();
727 }
728
729 /*
730 * Cached addresses - our own litle nis, not!
731 */
732 private static Cache addressCache = new Cache(Cache.Type.Positive);
733
734 private static Cache negativeCache = new Cache(Cache.Type.Negative);
735
736 private static boolean addressCacheInit = false;
737
738 static InetAddress[] unknown_array; // put THIS in cache
739
740 static InetAddressImpl impl;
741
742 private static final HashMap<String, Void> lookupTable = new HashMap<>();
743
744 /**
745 * Represents a cache entry
746 */
747 static final class CacheEntry {
748
749 CacheEntry(InetAddress[] addresses, long expiration) {
750 this.addresses = addresses;
751 this.expiration = expiration;
752 }
753
754 InetAddress[] addresses;
755 long expiration;
756 }
757
758 /**
759 * A cache that manages entries based on a policy specified
760 * at creation time.
761 */
762 static final class Cache {
763 private LinkedHashMap<String, CacheEntry> cache;
764 private Type type;
765
766 enum Type {Positive, Negative};
767
768 /**
769 * Create cache
770 */
771 public Cache(Type type) {
772 this.type = type;
773 cache = new LinkedHashMap<String, CacheEntry>();
774 }
775
776 private int getPolicy() {
777 if (type == Type.Positive) {
778 return InetAddressCachePolicy.get();
779 } else {
780 return InetAddressCachePolicy.getNegative();
781 }
782 }
783
784 /**
785 * Add an entry to the cache. If there's already an
786 * entry then for this host then the entry will be
787 * replaced.
788 */
789 public Cache put(String host, InetAddress[] addresses) {
790 int policy = getPolicy();
791 if (policy == InetAddressCachePolicy.NEVER) {
792 return this;
793 }
794
795 // purge any expired entries
796
797 if (policy != InetAddressCachePolicy.FOREVER) {
798
799 // As we iterate in insertion order we can
800 // terminate when a non-expired entry is found.
801 LinkedList<String> expired = new LinkedList<>();
802 long now = System.currentTimeMillis();
803 for (String key : cache.keySet()) {
804 CacheEntry entry = cache.get(key);
805
806 if (entry.expiration >= 0 && entry.expiration < now) {
807 expired.add(key);
808 } else {
809 break;
810 }
811 }
812
813 for (String key : expired) {
814 cache.remove(key);
815 }
816 }
817
818 // create new entry and add it to the cache
819 // -- as a HashMap replaces existing entries we
820 // don't need to explicitly check if there is
821 // already an entry for this host.
822 long expiration;
823 if (policy == InetAddressCachePolicy.FOREVER) {
824 expiration = -1;
825 } else {
826 expiration = System.currentTimeMillis() + (policy * 1000);
827 }
828 CacheEntry entry = new CacheEntry(addresses, expiration);
829 cache.put(host, entry);
830 return this;
831 }
832
833 /**
834 * Query the cache for the specific host. If found then
835 * return its CacheEntry, or null if not found.
836 */
837 public CacheEntry get(String host) {
838 int policy = getPolicy();
839 if (policy == InetAddressCachePolicy.NEVER) {
840 return null;
841 }
842 CacheEntry entry = cache.get(host);
843
844 // check if entry has expired
845 if (entry != null && policy != InetAddressCachePolicy.FOREVER) {
846 if (entry.expiration >= 0 &&
847 entry.expiration < System.currentTimeMillis()) {
848 cache.remove(host);
849 entry = null;
850 }
851 }
852
853 return entry;
854 }
855 }
856
857 /*
858 * Initialize cache and insert anyLocalAddress into the
859 * unknown array with no expiry.
860 */
861 private static void cacheInitIfNeeded() {
862 assert Thread.holdsLock(addressCache);
863 if (addressCacheInit) {
864 return;
865 }
866 unknown_array = new InetAddress[1];
867 unknown_array[0] = impl.anyLocalAddress();
868
869 addressCache.put(impl.anyLocalAddress().getHostName(),
870 unknown_array);
871
872 addressCacheInit = true;
873 }
874
875 /*
876 * Cache the given hostname and addresses.
877 */
878 private static void cacheAddresses(String hostname,
879 InetAddress[] addresses,
880 boolean success) {
881 hostname = hostname.toLowerCase();
882 synchronized (addressCache) {
883 cacheInitIfNeeded();
884 if (success) {
885 addressCache.put(hostname, addresses);
886 } else {
887 negativeCache.put(hostname, addresses);
888 }
889 }
890 }
891
892 /*
893 * Lookup hostname in cache (positive & negative cache). If
894 * found return addresses, null if not found.
895 */
896 private static InetAddress[] getCachedAddresses(String hostname) {
897 hostname = hostname.toLowerCase();
898
899 // search both positive & negative caches
900
901 synchronized (addressCache) {
902 cacheInitIfNeeded();
903
904 CacheEntry entry = addressCache.get(hostname);
905 if (entry == null) {
906 entry = negativeCache.get(hostname);
907 }
908
909 if (entry != null) {
910 return entry.addresses;
911 }
912 }
913
914 // not found
915 return null;
916 }
917
918 private static NameService createNSProvider(String provider) {
919 if (provider == null)
920 return null;
921
922 NameService nameService = null;
923 if (provider.equals("default")) {
924 // initialize the default name service
925 nameService = new NameService() {
926 public InetAddress[] lookupAllHostAddr(String host)
927 throws UnknownHostException {
928 return impl.lookupAllHostAddr(host);
929 }
930 public String getHostByAddr(byte[] addr)
931 throws UnknownHostException {
932 return impl.getHostByAddr(addr);
933 }
934 };
935 } else {
936 final String providerName = provider;
937 try {
938 nameService = java.security.AccessController.doPrivileged(
939 new java.security.PrivilegedExceptionAction<NameService>() {
940 public NameService run() {
941 Iterator<NameServiceDescriptor> itr =
942 ServiceLoader.load(NameServiceDescriptor.class)
943 .iterator();
944 while (itr.hasNext()) {
945 NameServiceDescriptor nsd = itr.next();
946 if (providerName.
947 equalsIgnoreCase(nsd.getType()+","
948 +nsd.getProviderName())) {
949 try {
950 return nsd.createNameService();
951 } catch (Exception e) {
952 e.printStackTrace();
953 System.err.println(
954 "Cannot create name service:"
955 +providerName+": " + e);
956 }
957 }
958 }
959
960 return null;
961 }
962 }
963 );
964 } catch (java.security.PrivilegedActionException e) {
965 }
966 }
967
968 return nameService;
969 }
970
971 static {
972 // create the impl
973 impl = InetAddressImplFactory.create();
974
975 // get name service if provided and requested
976 String provider = null;;
977 String propPrefix = "sun.net.spi.nameservice.provider.";
978 int n = 1;
979 nameServices = new ArrayList<NameService>();
980 provider = AccessController.doPrivileged(
981 new GetPropertyAction(propPrefix + n));
982 while (provider != null) {
983 NameService ns = createNSProvider(provider);
984 if (ns != null)
985 nameServices.add(ns);
986
987 n++;
988 provider = AccessController.doPrivileged(
989 new GetPropertyAction(propPrefix + n));
990 }
991
992 // if not designate any name services provider,
993 // create a default one
994 if (nameServices.size() == 0) {
995 NameService ns = createNSProvider("default");
996 nameServices.add(ns);
997 }
998 }
999
1000 /**
1001 * Creates an InetAddress based on the provided host name and IP address.
1002 * No name service is checked for the validity of the address.
1003 *
1004 * <p> The host name can either be a machine name, such as
1005 * "{@code java.sun.com}", or a textual representation of its IP
1006 * address.
1007 * <p> No validity checking is done on the host name either.
1008 *
1009 * <p> If addr specifies an IPv4 address an instance of Inet4Address
1010 * will be returned; otherwise, an instance of Inet6Address
1011 * will be returned.
1012 *
1013 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1014 * must be 16 bytes long
1015 *
1016 * @param host the specified host
1017 * @param addr the raw IP address in network byte order
1018 * @return an InetAddress object created from the raw IP address.
1019 * @exception UnknownHostException if IP address is of illegal length
1020 * @since 1.4
1021 */
1022 public static InetAddress getByAddress(String host, byte[] addr)
1023 throws UnknownHostException {
1024 if (host != null && host.length() > 0 && host.charAt(0) == '[') {
1025 if (host.charAt(host.length()-1) == ']') {
1026 host = host.substring(1, host.length() -1);
1027 }
1028 }
1029 if (addr != null) {
1030 if (addr.length == Inet4Address.INADDRSZ) {
1031 return new Inet4Address(host, addr);
1032 } else if (addr.length == Inet6Address.INADDRSZ) {
1033 byte[] newAddr
1034 = IPAddressUtil.convertFromIPv4MappedAddress(addr);
1035 if (newAddr != null) {
1036 return new Inet4Address(host, newAddr);
1037 } else {
1038 return new Inet6Address(host, addr);
1039 }
1040 }
1041 }
1042 throw new UnknownHostException("addr is of illegal length");
1043 }
1044
1045
1046 /**
1047 * Determines the IP address of a host, given the host's name.
1048 *
1049 * <p> The host name can either be a machine name, such as
1050 * "{@code java.sun.com}", or a textual representation of its
1051 * IP address. If a literal IP address is supplied, only the
1052 * validity of the address format is checked.
1053 *
1054 * <p> For {@code host} specified in literal IPv6 address,
1055 * either the form defined in RFC 2732 or the literal IPv6 address
1056 * format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
1057 * supported. See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
1058 * scoped addresses.
1059 *
1060 * <p> If the host is {@code null} then an {@code InetAddress}
1061 * representing an address of the loopback interface is returned.
1062 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1063 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1064 * section 2.5.3. </p>
1065 *
1066 * @param host the specified host, or {@code null}.
1067 * @return an IP address for the given host name.
1068 * @exception UnknownHostException if no IP address for the
1069 * {@code host} could be found, or if a scope_id was specified
1070 * for a global IPv6 address.
1071 * @exception SecurityException if a security manager exists
1072 * and its checkConnect method doesn't allow the operation
1073 */
1074 public static InetAddress getByName(String host)
1075 throws UnknownHostException {
1076 return InetAddress.getAllByName(host)[0];
1077 }
1078
1079 // called from deployment cache manager
1080 private static InetAddress getByName(String host, InetAddress reqAddr)
1081 throws UnknownHostException {
1082 return InetAddress.getAllByName(host, reqAddr)[0];
1083 }
1084
1085 /**
1086 * Given the name of a host, returns an array of its IP addresses,
1087 * based on the configured name service on the system.
1088 *
1089 * <p> The host name can either be a machine name, such as
1090 * "{@code java.sun.com}", or a textual representation of its IP
1091 * address. If a literal IP address is supplied, only the
1092 * validity of the address format is checked.
1093 *
1094 * <p> For {@code host} specified in <i>literal IPv6 address</i>,
1095 * either the form defined in RFC 2732 or the literal IPv6 address
1096 * format defined in RFC 2373 is accepted. A literal IPv6 address may
1097 * also be qualified by appending a scoped zone identifier or scope_id.
1098 * The syntax and usage of scope_ids is described
1099 * <a href="Inet6Address.html#scoped">here</a>.
1100 * <p> If the host is {@code null} then an {@code InetAddress}
1101 * representing an address of the loopback interface is returned.
1102 * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
1103 * section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
1104 * section 2.5.3. </p>
1105 *
1106 * <p> If there is a security manager and {@code host} is not
1107 * null and {@code host.length() } is not equal to zero, the
1108 * security manager's
1109 * {@code checkConnect} method is called
1110 * with the hostname and {@code -1}
1111 * as its arguments to see if the operation is allowed.
1112 *
1113 * @param host the name of the host, or {@code null}.
1114 * @return an array of all the IP addresses for a given host name.
1115 *
1116 * @exception UnknownHostException if no IP address for the
1117 * {@code host} could be found, or if a scope_id was specified
1118 * for a global IPv6 address.
1119 * @exception SecurityException if a security manager exists and its
1120 * {@code checkConnect} method doesn't allow the operation.
1121 *
1122 * @see SecurityManager#checkConnect
1123 */
1124 public static InetAddress[] getAllByName(String host)
1125 throws UnknownHostException {
1126 return getAllByName(host, null);
1127 }
1128
1129 private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
1130 throws UnknownHostException {
1131
1132 if (host == null || host.length() == 0) {
1133 InetAddress[] ret = new InetAddress[1];
1134 ret[0] = impl.loopbackAddress();
1135 return ret;
1136 }
1137
1138 boolean ipv6Expected = false;
1139 if (host.charAt(0) == '[') {
1140 // This is supposed to be an IPv6 literal
1141 if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1142 host = host.substring(1, host.length() -1);
1143 ipv6Expected = true;
1144 } else {
1145 // This was supposed to be a IPv6 address, but it's not!
1146 throw new UnknownHostException(host + ": invalid IPv6 address");
1147 }
1148 }
1149
1150 // if host is an IP address, we won't do further lookup
1151 if (Character.digit(host.charAt(0), 16) != -1
1152 || (host.charAt(0) == ':')) {
1153 byte[] addr = null;
1154 int numericZone = -1;
1155 String ifname = null;
1156 // see if it is IPv4 address
1157 addr = IPAddressUtil.textToNumericFormatV4(host);
1158 if (addr == null) {
1159 // This is supposed to be an IPv6 literal
1160 // Check if a numeric or string zone id is present
1161 int pos;
1162 if ((pos=host.indexOf ("%")) != -1) {
1163 numericZone = checkNumericZone (host);
1164 if (numericZone == -1) { /* remainder of string must be an ifname */
1165 ifname = host.substring (pos+1);
1166 }
1167 }
1168 if ((addr = IPAddressUtil.textToNumericFormatV6(host)) == null && host.contains(":")) {
1169 throw new UnknownHostException(host + ": invalid IPv6 address");
1170 }
1171 } else if (ipv6Expected) {
1172 // Means an IPv4 litteral between brackets!
1173 throw new UnknownHostException("["+host+"]");
1174 }
1175 InetAddress[] ret = new InetAddress[1];
1176 if(addr != null) {
1177 if (addr.length == Inet4Address.INADDRSZ) {
1178 ret[0] = new Inet4Address(null, addr);
1179 } else {
1180 if (ifname != null) {
1181 ret[0] = new Inet6Address(null, addr, ifname);
1182 } else {
1183 ret[0] = new Inet6Address(null, addr, numericZone);
1184 }
1185 }
1186 return ret;
1187 }
1188 } else if (ipv6Expected) {
1189 // We were expecting an IPv6 Litteral, but got something else
1190 throw new UnknownHostException("["+host+"]");
1191 }
1192 return getAllByName0(host, reqAddr, true);
1193 }
1194
1195 /**
1196 * Returns the loopback address.
1197 * <p>
1198 * The InetAddress returned will represent the IPv4
1199 * loopback address, 127.0.0.1, or the IPv6 loopback
1200 * address, ::1. The IPv4 loopback address returned
1201 * is only one of many in the form 127.*.*.*
1202 *
1203 * @return the InetAddress loopback instance.
1204 * @since 1.7
1205 */
1206 public static InetAddress getLoopbackAddress() {
1207 return impl.loopbackAddress();
1208 }
1209
1210
1211 /**
1212 * check if the literal address string has %nn appended
1213 * returns -1 if not, or the numeric value otherwise.
1214 *
1215 * %nn may also be a string that represents the displayName of
1216 * a currently available NetworkInterface.
1217 */
1218 private static int checkNumericZone (String s) throws UnknownHostException {
1219 int percent = s.indexOf ('%');
1220 int slen = s.length();
1221 int digit, zone=0;
1222 if (percent == -1) {
1223 return -1;
1224 }
1225 for (int i=percent+1; i<slen; i++) {
1226 char c = s.charAt(i);
1227 if (c == ']') {
1228 if (i == percent+1) {
1229 /* empty per-cent field */
1230 return -1;
1231 }
1232 break;
1233 }
1234 if ((digit = Character.digit (c, 10)) < 0) {
1235 return -1;
1236 }
1237 zone = (zone * 10) + digit;
1238 }
1239 return zone;
1240 }
1241
1242 private static InetAddress[] getAllByName0 (String host)
1243 throws UnknownHostException
1244 {
1245 return getAllByName0(host, true);
1246 }
1247
1248 /**
1249 * package private so SocketPermission can call it
1250 */
1251 static InetAddress[] getAllByName0 (String host, boolean check)
1252 throws UnknownHostException {
1253 return getAllByName0 (host, null, check);
1254 }
1255
1256 private static InetAddress[] getAllByName0 (String host, InetAddress reqAddr, boolean check)
1257 throws UnknownHostException {
1258
1259 /* If it gets here it is presumed to be a hostname */
1260 /* Cache.get can return: null, unknownAddress, or InetAddress[] */
1261
1262 /* make sure the connection to the host is allowed, before we
1263 * give out a hostname
1264 */
1265 if (check) {
1266 SecurityManager security = System.getSecurityManager();
1267 if (security != null) {
1268 security.checkConnect(host, -1);
1269 }
1270 }
1271
1272 InetAddress[] addresses = getCachedAddresses(host);
1273
1274 /* If no entry in cache, then do the host lookup */
1275 if (addresses == null) {
1276 addresses = getAddressesFromNameService(host, reqAddr);
1277 }
1278
1279 if (addresses == unknown_array)
1280 throw new UnknownHostException(host);
1281
1282 return addresses.clone();
1283 }
1284
1285 private static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
1286 throws UnknownHostException
1287 {
1288 InetAddress[] addresses = null;
1289 boolean success = false;
1290 UnknownHostException ex = null;
1291
1292 // Check whether the host is in the lookupTable.
1293 // 1) If the host isn't in the lookupTable when
1294 // checkLookupTable() is called, checkLookupTable()
1295 // would add the host in the lookupTable and
1296 // return null. So we will do the lookup.
1297 // 2) If the host is in the lookupTable when
1298 // checkLookupTable() is called, the current thread
1299 // would be blocked until the host is removed
1300 // from the lookupTable. Then this thread
1301 // should try to look up the addressCache.
1302 // i) if it found the addresses in the
1303 // addressCache, checkLookupTable() would
1304 // return the addresses.
1305 // ii) if it didn't find the addresses in the
1306 // addressCache for any reason,
1307 // it should add the host in the
1308 // lookupTable and return null so the
1309 // following code would do a lookup itself.
1310 if ((addresses = checkLookupTable(host)) == null) {
1311 try {
1312 // This is the first thread which looks up the addresses
1313 // this host or the cache entry for this host has been
1314 // expired so this thread should do the lookup.
1315 for (NameService nameService : nameServices) {
1316 try {
1317 /*
1318 * Do not put the call to lookup() inside the
1319 * constructor. if you do you will still be
1320 * allocating space when the lookup fails.
1321 */
1322
1323 addresses = nameService.lookupAllHostAddr(host);
1324 success = true;
1325 break;
1326 } catch (UnknownHostException uhe) {
1327 if (host.equalsIgnoreCase("localhost")) {
1328 InetAddress[] local = new InetAddress[] { impl.loopbackAddress() };
1329 addresses = local;
1330 success = true;
1331 break;
1332 }
1333 else {
1334 addresses = unknown_array;
1335 success = false;
1336 ex = uhe;
1337 }
1338 }
1339 }
1340
1341 // More to do?
1342 if (reqAddr != null && addresses.length > 1 && !addresses[0].equals(reqAddr)) {
1343 // Find it?
1344 int i = 1;
1345 for (; i < addresses.length; i++) {
1346 if (addresses[i].equals(reqAddr)) {
1347 break;
1348 }
1349 }
1350 // Rotate
1351 if (i < addresses.length) {
1352 InetAddress tmp, tmp2 = reqAddr;
1353 for (int j = 0; j < i; j++) {
1354 tmp = addresses[j];
1355 addresses[j] = tmp2;
1356 tmp2 = tmp;
1357 }
1358 addresses[i] = tmp2;
1359 }
1360 }
1361 // Cache the address.
1362 cacheAddresses(host, addresses, success);
1363
1364 if (!success && ex != null)
1365 throw ex;
1366
1367 } finally {
1368 // Delete host from the lookupTable and notify
1369 // all threads waiting on the lookupTable monitor.
1370 updateLookupTable(host);
1371 }
1372 }
1373
1374 return addresses;
1375 }
1376
1377
1378 private static InetAddress[] checkLookupTable(String host) {
1379 synchronized (lookupTable) {
1380 // If the host isn't in the lookupTable, add it in the
1381 // lookuptable and return null. The caller should do
1382 // the lookup.
1383 if (lookupTable.containsKey(host) == false) {
1384 lookupTable.put(host, null);
1385 return null;
1386 }
1387
1388 // If the host is in the lookupTable, it means that another
1389 // thread is trying to look up the addresses of this host.
1390 // This thread should wait.
1391 while (lookupTable.containsKey(host)) {
1392 try {
1393 lookupTable.wait();
1394 } catch (InterruptedException e) {
1395 }
1396 }
1397 }
1398
1399 // The other thread has finished looking up the addresses of
1400 // the host. This thread should retry to get the addresses
1401 // from the addressCache. If it doesn't get the addresses from
1402 // the cache, it will try to look up the addresses itself.
1403 InetAddress[] addresses = getCachedAddresses(host);
1404 if (addresses == null) {
1405 synchronized (lookupTable) {
1406 lookupTable.put(host, null);
1407 return null;
1408 }
1409 }
1410
1411 return addresses;
1412 }
1413
1414 private static void updateLookupTable(String host) {
1415 synchronized (lookupTable) {
1416 lookupTable.remove(host);
1417 lookupTable.notifyAll();
1418 }
1419 }
1420
1421 /**
1422 * Returns an {@code InetAddress} object given the raw IP address .
1423 * The argument is in network byte order: the highest order
1424 * byte of the address is in {@code getAddress()[0]}.
1425 *
1426 * <p> This method doesn't block, i.e. no reverse name service lookup
1427 * is performed.
1428 *
1429 * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1430 * must be 16 bytes long
1431 *
1432 * @param addr the raw IP address in network byte order
1433 * @return an InetAddress object created from the raw IP address.
1434 * @exception UnknownHostException if IP address is of illegal length
1435 * @since 1.4
1436 */
1437 public static InetAddress getByAddress(byte[] addr)
1438 throws UnknownHostException {
1439 return getByAddress(null, addr);
1440 }
1441
1442 private static InetAddress cachedLocalHost = null;
1443 private static long cacheTime = 0;
1444 private static final long maxCacheTime = 5000L;
1445 private static final Object cacheLock = new Object();
1446
1447 /**
1448 * Returns the address of the local host. This is achieved by retrieving
1449 * the name of the host from the system, then resolving that name into
1450 * an {@code InetAddress}.
1451 *
1452 * <P>Note: The resolved address may be cached for a short period of time.
1453 * </P>
1454 *
1455 * <p>If there is a security manager, its
1456 * {@code checkConnect} method is called
1457 * with the local host name and {@code -1}
1458 * as its arguments to see if the operation is allowed.
1459 * If the operation is not allowed, an InetAddress representing
1460 * the loopback address is returned.
1461 *
1462 * @return the address of the local host.
1463 *
1464 * @exception UnknownHostException if the local host name could not
1465 * be resolved into an address.
1466 *
1467 * @see SecurityManager#checkConnect
1468 * @see java.net.InetAddress#getByName(java.lang.String)
1469 */
1470 public static InetAddress getLocalHost() throws UnknownHostException {
1471
1472 SecurityManager security = System.getSecurityManager();
1473 try {
1474 String local = impl.getLocalHostName();
1475
1476 if (security != null) {
1477 security.checkConnect(local, -1);
1478 }
1479
1480 if (local.equals("localhost")) {
1481 return impl.loopbackAddress();
1482 }
1483
1484 InetAddress ret = null;
1485 synchronized (cacheLock) {
1486 long now = System.currentTimeMillis();
1487 if (cachedLocalHost != null) {
1488 if ((now - cacheTime) < maxCacheTime) // Less than 5s old?
1489 ret = cachedLocalHost;
1490 else
1491 cachedLocalHost = null;
1492 }
1493
1494 // we are calling getAddressesFromNameService directly
1495 // to avoid getting localHost from cache
1496 if (ret == null) {
1497 InetAddress[] localAddrs;
1498 try {
1499 localAddrs =
1500 InetAddress.getAddressesFromNameService(local, null);
1501 } catch (UnknownHostException uhe) {
1502 // Rethrow with a more informative error message.
1503 UnknownHostException uhe2 =
1504 new UnknownHostException(local + ": " +
1505 uhe.getMessage());
1506 uhe2.initCause(uhe);
1507 throw uhe2;
1508 }
1509 cachedLocalHost = localAddrs[0];
1510 cacheTime = now;
1511 ret = localAddrs[0];
1512 }
1513 }
1514 return ret;
1515 } catch (java.lang.SecurityException e) {
1516 return impl.loopbackAddress();
1517 }
1518 }
1519
1520 /**
1521 * Perform class load-time initializations.
1522 */
1523 private static native void init();
1524
1525
1526 /*
1527 * Returns the InetAddress representing anyLocalAddress
1528 * (typically 0.0.0.0 or ::0)
1529 */
1530 static InetAddress anyLocalAddress() {
1531 return impl.anyLocalAddress();
1532 }
1533
1534 /*
1535 * Load and instantiate an underlying impl class
1536 */
1537 static InetAddressImpl loadImpl(String implName) {
1538 Object impl = null;
1539
1540 /*
1541 * Property "impl.prefix" will be prepended to the classname
1542 * of the implementation object we instantiate, to which we
1543 * delegate the real work (like native methods). This
1544 * property can vary across implementations of the java.
1545 * classes. The default is an empty String "".
1546 */
1547 String prefix = AccessController.doPrivileged(
1548 new GetPropertyAction("impl.prefix", ""));
1549 try {
1550 impl = Class.forName("java.net." + prefix + implName).newInstance();
1551 } catch (ClassNotFoundException e) {
1552 System.err.println("Class not found: java.net." + prefix +
1553 implName + ":\ncheck impl.prefix property " +
1554 "in your properties file.");
1555 } catch (InstantiationException e) {
1556 System.err.println("Could not instantiate: java.net." + prefix +
1557 implName + ":\ncheck impl.prefix property " +
1558 "in your properties file.");
1559 } catch (IllegalAccessException e) {
1560 System.err.println("Cannot access class: java.net." + prefix +
1561 implName + ":\ncheck impl.prefix property " +
1562 "in your properties file.");
1563 }
1564
1565 if (impl == null) {
1566 try {
1567 impl = Class.forName(implName).newInstance();
1568 } catch (Exception e) {
1569 throw new Error("System property impl.prefix incorrect");
1570 }
1571 }
1572
1573 return (InetAddressImpl) impl;
1574 }
1575
1576 private void readObjectNoData (ObjectInputStream s) throws
1577 IOException, ClassNotFoundException {
1578 if (getClass().getClassLoader() != null) {
1579 throw new SecurityException ("invalid address type");
1580 }
1581 }
1582
1583 private static final long FIELDS_OFFSET;
1584 private static final sun.misc.Unsafe UNSAFE;
1585
1586 static {
1587 try {
1588 sun.misc.Unsafe unsafe = sun.misc.Unsafe.getUnsafe();
1589 FIELDS_OFFSET = unsafe.objectFieldOffset(
1590 InetAddress.class.getDeclaredField("holder")
1591 );
1592 UNSAFE = unsafe;
1593 } catch (ReflectiveOperationException e) {
1594 throw new Error(e);
1595 }
1596 }
1597
1598 private void readObject (ObjectInputStream s) throws
1599 IOException, ClassNotFoundException {
1600 if (getClass().getClassLoader() != null) {
1601 throw new SecurityException ("invalid address type");
1602 }
1603 GetField gf = s.readFields();
1604 String host = (String)gf.get("hostName", null);
1605 int address= gf.get("address", 0);
1606 int family= gf.get("family", 0);
1607 InetAddressHolder h = new InetAddressHolder(host, address, family);
1608 UNSAFE.putObject(this, FIELDS_OFFSET, h);
1609 }
1610
1611 /* needed because the serializable fields no longer exist */
1612
1613 /**
1614 * @serialField hostName String
1615 * @serialField address int
1616 * @serialField family int
1617 */
1618 private static final ObjectStreamField[] serialPersistentFields = {
1619 new ObjectStreamField("hostName", String.class),
1620 new ObjectStreamField("address", int.class),
1621 new ObjectStreamField("family", int.class),
1622 };
1623
1624 private void writeObject (ObjectOutputStream s) throws
1625 IOException {
1626 if (getClass().getClassLoader() != null) {
1627 throw new SecurityException ("invalid address type");
1628 }
1629 PutField pf = s.putFields();
1630 pf.put("hostName", holder().getHostName());
1631 pf.put("address", holder().getAddress());
1632 pf.put("family", holder().getFamily());
1633 s.writeFields();
1634 }
1635 }
1636
1637 /*
1638 * Simple factory to create the impl
1639 */
1640 class InetAddressImplFactory {
1641
1642 static InetAddressImpl create() {
1643 return InetAddress.loadImpl(isIPv6Supported() ?
1644 "Inet6AddressImpl" : "Inet4AddressImpl");
1645 }
1646
1647 static native boolean isIPv6Supported();
1648 }
1649