1 /*
   2  * Copyright (c) 1995, 2021, 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.net.spi.InetAddressResolver;
  29 import java.net.spi.InetAddressResolverProvider;
  30 import java.net.spi.InetAddressResolver.LookupPolicy;
  31 import java.security.AccessController;
  32 import java.security.PrivilegedAction;
  33 import java.util.List;
  34 import java.util.NavigableSet;
  35 import java.util.ArrayList;
  36 import java.util.Objects;
  37 import java.util.Scanner;
  38 import java.io.File;
  39 import java.io.ObjectStreamException;
  40 import java.io.ObjectStreamField;
  41 import java.io.IOException;
  42 import java.io.InvalidObjectException;
  43 import java.io.ObjectInputStream;
  44 import java.io.ObjectInputStream.GetField;
  45 import java.io.ObjectOutputStream;
  46 import java.io.ObjectOutputStream.PutField;
  47 import java.lang.annotation.Native;
  48 import java.util.ServiceLoader;
  49 import java.util.concurrent.ConcurrentHashMap;
  50 import java.util.concurrent.ConcurrentMap;
  51 import java.util.concurrent.ConcurrentSkipListSet;
  52 import java.util.concurrent.atomic.AtomicLong;
  53 import java.util.Arrays;
  54 import java.util.concurrent.locks.ReentrantLock;
  55 import java.util.stream.Stream;
  56 
  57 import jdk.internal.misc.VM;
  58 
  59 import jdk.internal.access.JavaNetInetAddressAccess;
  60 import jdk.internal.access.SharedSecrets;
  61 import jdk.internal.vm.annotation.Stable;
  62 import sun.net.ResolverProviderConfiguration;
  63 import sun.security.action.*;
  64 import sun.net.InetAddressCachePolicy;
  65 import sun.net.util.IPAddressUtil;
  66 import sun.nio.cs.UTF_8;
  67 
  68 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV4;
  69 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV4_FIRST;
  70 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV6;
  71 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV6_FIRST;
  72 
  73 /**
  74  * This class represents an Internet Protocol (IP) address.
  75  *
  76  * <p> An IP address is either a 32-bit or 128-bit unsigned number
  77  * used by IP, a lower-level protocol on which protocols like UDP and
  78  * TCP are built. The IP address architecture is defined by <a
  79  * href="http://www.ietf.org/rfc/rfc790.txt"><i>RFC&nbsp;790:
  80  * Assigned Numbers</i></a>, <a
  81  * href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC&nbsp;1918:
  82  * Address Allocation for Private Internets</i></a>, <a
  83  * href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC&nbsp;2365:
  84  * Administratively Scoped IP Multicast</i></a>, and <a
  85  * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC&nbsp;2373: IP
  86  * Version 6 Addressing Architecture</i></a>. An instance of an
  87  * InetAddress consists of an IP address and possibly its
  88  * corresponding host name (depending on whether it is constructed
  89  * with a host name or whether it has already done reverse host name
  90  * resolution).
  91  *
  92  * <h2> Address types </h2>
  93  *
  94  * <table class="striped" style="margin-left:2em">
  95  *   <caption style="display:none">Description of unicast and multicast address types</caption>
  96  *   <thead>
  97  *   <tr><th scope="col">Address Type</th><th scope="col">Description</th></tr>
  98  *   </thead>
  99  *   <tbody>
 100  *   <tr><th scope="row" style="vertical-align:top">unicast</th>
 101  *       <td>An identifier for a single interface. A packet sent to
 102  *         a unicast address is delivered to the interface identified by
 103  *         that address.
 104  *
 105  *         <p> The Unspecified Address -- Also called anylocal or wildcard
 106  *         address. It must never be assigned to any node. It indicates the
 107  *         absence of an address. One example of its use is as the target of
 108  *         bind, which allows a server to accept a client connection on any
 109  *         interface, in case the server host has multiple interfaces.
 110  *
 111  *         <p> The <i>unspecified</i> address must not be used as
 112  *         the destination address of an IP packet.
 113  *
 114  *         <p> The <i>Loopback</i> Addresses -- This is the address
 115  *         assigned to the loopback interface. Anything sent to this
 116  *         IP address loops around and becomes IP input on the local
 117  *         host. This address is often used when testing a
 118  *         client.</td></tr>
 119  *   <tr><th scope="row" style="vertical-align:top">multicast</th>
 120  *       <td>An identifier for a set of interfaces (typically belonging
 121  *         to different nodes). A packet sent to a multicast address is
 122  *         delivered to all interfaces identified by that address.</td></tr>
 123  * </tbody>
 124  * </table>
 125  *
 126  * <h3> IP address scope </h3>
 127  *
 128  * <p> <i>Link-local</i> addresses are designed to be used for addressing
 129  * on a single link for purposes such as auto-address configuration,
 130  * neighbor discovery, or when no routers are present.
 131  *
 132  * <p> <i>Site-local</i> addresses are designed to be used for addressing
 133  * inside of a site without the need for a global prefix.
 134  *
 135  * <p> <i>Global</i> addresses are unique across the internet.
 136  *
 137  * <h3> Textual representation of IP addresses </h3>
 138  *
 139  * The textual representation of an IP address is address family specific.
 140  *
 141  * <p>
 142  *
 143  * For IPv4 address format, please refer to <A
 144  * HREF="Inet4Address.html#format">Inet4Address#format</A>; For IPv6
 145  * address format, please refer to <A
 146  * HREF="Inet6Address.html#format">Inet6Address#format</A>.
 147  *
 148  * <p> There is a <a href="doc-files/net-properties.html#Ipv4IPv6">couple of
 149  * System Properties</a> affecting how IPv4 and IPv6 addresses are used.
 150  *
 151  * <h2 id="host-name-resolution"> Host Name Resolution </h2>
 152  *
 153  * <p> The InetAddress class provides methods to resolve host names to
 154  * their IP addresses and vice versa. The actual resolution is delegated to an
 155  * {@linkplain InetAddressResolver InetAddress resolver}.
 156  *
 157  * <p> <i>Host name-to-IP address resolution</i> maps a host name to an IP address.
 158  * For any host name, its corresponding IP address is returned.




 159  *
 160  * <p> <i>Reverse name resolution</i> means that for any IP address,
 161  * the host associated with the IP address is returned.
 162  *
 163  * <p id="built-in-resolver"> The built-in InetAddress resolver implementation does
 164  * host name-to-IP address resolution and vice versa through the use of
 165  * a combination of local machine configuration information and network
 166  * naming services such as the Domain Name System (DNS) and the Lightweight Directory
 167  * Access Protocol (LDAP).
 168  * The particular naming services that the built-in resolver uses by default
 169  * depends on the configuration of the local machine.
 170  *
 171  * <p> {@code InetAddress} has a service provider mechanism for InetAddress resolvers
 172  * that allows a custom InetAddress resolver to be used instead of the built-in implementation.
 173  * {@link InetAddressResolverProvider} is the service provider class. Its API docs provide all the
 174  * details on this mechanism.
 175  *
 176  * <h2> InetAddress Caching </h2>
 177  *
 178  * The InetAddress class has a cache to store successful as well as
 179  * unsuccessful host name resolutions.
 180  *
 181  * <p> By default, when a security manager is installed, in order to
 182  * protect against DNS spoofing attacks,
 183  * the result of positive host name resolutions are
 184  * cached forever. When a security manager is not installed, the default
 185  * behavior is to cache entries for a finite (implementation dependent)
 186  * period of time. The result of unsuccessful host
 187  * name resolution is cached for a very short period of time (10
 188  * seconds) to improve performance.
 189  *
 190  * <p> If the default behavior is not desired, then a Java security property
 191  * can be set to a different Time-to-live (TTL) value for positive
 192  * caching. Likewise, a system admin can configure a different
 193  * negative caching TTL value when needed.
 194  *
 195  * <p> Two Java security properties control the TTL values used for
 196  *  positive and negative host name resolution caching:
 197  *
 198  * <dl style="margin-left:2em">
 199  * <dt><b>networkaddress.cache.ttl</b></dt>
 200  * <dd>Indicates the caching policy for successful name lookups from
 201  * the name service. The value is specified as an integer to indicate
 202  * the number of seconds to cache the successful lookup. The default
 203  * setting is to cache for an implementation specific period of time.
 204  * <p>
 205  * A value of -1 indicates "cache forever".
 206  * </dd>
 207  * <dt><b>networkaddress.cache.negative.ttl</b> (default: 10)</dt>
 208  * <dd>Indicates the caching policy for un-successful name lookups
 209  * from the name service. The value is specified as an integer to
 210  * indicate the number of seconds to cache the failure for
 211  * un-successful lookups.
 212  * <p>
 213  * A value of 0 indicates "never cache".
 214  * A value of -1 indicates "cache forever".
 215  * </dd>
 216  * </dl>
 217  *
 218  * @author  Chris Warth
 219  * @see     java.net.InetAddress#getByAddress(byte[])
 220  * @see     java.net.InetAddress#getByAddress(java.lang.String, byte[])
 221  * @see     java.net.InetAddress#getAllByName(java.lang.String)
 222  * @see     java.net.InetAddress#getByName(java.lang.String)
 223  * @see     java.net.InetAddress#getLocalHost()
 224  * @since 1.0
 225  */
 226 public class InetAddress implements java.io.Serializable {
 227 




 228     /**
 229      * Specify the address family: Internet Protocol, Version 4
 230      * @since 1.4
 231      */
 232     @Native static final int IPv4 = 1;
 233 
 234     /**
 235      * Specify the address family: Internet Protocol, Version 6
 236      * @since 1.4
 237      */
 238     @Native static final int IPv6 = 2;
 239 



 240     static class InetAddressHolder {
 241         /**
 242          * Reserve the original application specified hostname.
 243          *
 244          * The original hostname is useful for domain-based endpoint
 245          * identification (see RFC 2818 and RFC 6125).  If an address
 246          * was created with a raw IP address, a reverse name lookup
 247          * may introduce endpoint identification security issue via
 248          * DNS forging.
 249          *
 250          * Oracle JSSE provider is using this original hostname, via
 251          * jdk.internal.misc.JavaNetAccess, for SSL/TLS endpoint identification.
 252          *
 253          * Note: May define a new public method in the future if necessary.
 254          */
 255         String originalHostName;
 256 
 257         InetAddressHolder() {}
 258 
 259         InetAddressHolder(String hostName, int address, int family) {
 260             this.originalHostName = hostName;
 261             this.hostName = hostName;
 262             this.address = address;
 263             this.family = family;
 264         }
 265 
 266         void init(String hostName, int family) {
 267             this.originalHostName = hostName;
 268             this.hostName = hostName;
 269             if (family != -1) {
 270                 this.family = family;
 271             }
 272         }
 273 
 274         String hostName;
 275 
 276         String getHostName() {
 277             return hostName;
 278         }
 279 
 280         String getOriginalHostName() {
 281             return originalHostName;
 282         }
 283 
 284         /**
 285          * Holds a 32-bit IPv4 address.
 286          */
 287         int address;
 288 
 289         int getAddress() {
 290             return address;
 291         }
 292 
 293         /**
 294          * Specifies the address family type, for instance, '1' for IPv4
 295          * addresses, and '2' for IPv6 addresses.
 296          */
 297         int family;
 298 
 299         int getFamily() {
 300             return family;
 301         }
 302     }
 303 
 304     /* Used to store the serializable fields of InetAddress */
 305     final transient InetAddressHolder holder;
 306 
 307     InetAddressHolder holder() {
 308         return holder;
 309     }
 310 
 311     /* Used to store the system-wide resolver */
 312     @Stable
 313     private static volatile InetAddressResolver resolver;
 314 
 315     private static final InetAddressResolver BUILTIN_RESOLVER;
 316 
 317     /**
 318      * Used to store the best available hostname.
 319      * Lazily initialized via a data race; safe because Strings are immutable.
 320      */
 321     private transient String canonicalHostName = null;
 322 
 323     /** use serialVersionUID from JDK 1.0.2 for interoperability */
 324     @java.io.Serial
 325     private static final long serialVersionUID = 3286316764910316507L;
 326 
 327     // "java.net.preferIPv4Stack" system property value
 328     private static final String PREFER_IPV4_STACK_VALUE;
 329 
 330     // "java.net.preferIPv6Addresses" system property value
 331     private static final String PREFER_IPV6_ADDRESSES_VALUE;
 332 
 333     // "jdk.net.hosts.file" system property value
 334     private static final String HOSTS_FILE_NAME;
 335 
 336     /*
 337      * Load net library into runtime, and perform initializations.
 338      */
 339     static {
 340         PREFER_IPV4_STACK_VALUE =
 341                 GetPropertyAction.privilegedGetProperty("java.net.preferIPv4Stack");
 342         PREFER_IPV6_ADDRESSES_VALUE =
 343                 GetPropertyAction.privilegedGetProperty("java.net.preferIPv6Addresses");
 344         HOSTS_FILE_NAME =
 345                 GetPropertyAction.privilegedGetProperty("jdk.net.hosts.file");






 346         jdk.internal.loader.BootLoader.loadLibrary("net");
 347         SharedSecrets.setJavaNetInetAddressAccess(
 348                 new JavaNetInetAddressAccess() {
 349                     public String getOriginalHostName(InetAddress ia) {
 350                         return ia.holder.getOriginalHostName();
 351                     }
 352 







 353                     public int addressValue(Inet4Address inet4Address) {
 354                         return inet4Address.addressValue();
 355                     }
 356 
 357                     public byte[] addressBytes(Inet6Address inet6Address) {
 358                         return inet6Address.addressBytes();
 359                     }
 360                 }
 361         );
 362         init();
 363     }
 364 
 365     /**
 366      * Creates an address lookup policy from {@code "java.net.preferIPv4Stack"},
 367      * {@code "java.net.preferIPv6Addresses"} system property values, and O/S configuration.
 368      */
 369     private static final LookupPolicy initializePlatformLookupPolicy() {
 370         // Calculate AddressFamily value first
 371         boolean ipv4Available = isIPv4Available();
 372         if ("true".equals(PREFER_IPV4_STACK_VALUE) && ipv4Available) {
 373             return LookupPolicy.of(IPV4);
 374         }
 375         // Check if IPv6 is not supported
 376         if (InetAddress.impl instanceof Inet4AddressImpl) {
 377             return LookupPolicy.of(IPV4);
 378         }
 379         // Check if system supports IPv4, if not use IPv6
 380         if (!ipv4Available) {
 381             return LookupPolicy.of(IPV6);
 382         }
 383         // If both address families are needed - check preferIPv6Addresses value
 384         if (PREFER_IPV6_ADDRESSES_VALUE != null) {
 385             if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("true")) {
 386                 return LookupPolicy.of(IPV4 | IPV6 | IPV6_FIRST);
 387             }
 388             if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("false")) {
 389                 return LookupPolicy.of(IPV4 | IPV6 | IPV4_FIRST);
 390             }
 391             if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("system")) {
 392                 return LookupPolicy.of(IPV4 | IPV6);
 393             }
 394         }
 395         // Default value with both address families needed - IPv4 addresses come first
 396         return LookupPolicy.of(IPV4 | IPV6 | IPV4_FIRST);
 397     }
 398 
 399     static boolean systemAddressesOrder(int lookupCharacteristics) {
 400         return (lookupCharacteristics & (IPV4_FIRST | IPV6_FIRST)) == 0;
 401     }
 402 
 403     static boolean ipv4AddressesFirst(int lookupCharacteristics) {
 404         return (lookupCharacteristics & IPV4_FIRST) != 0;
 405     }
 406 
 407     static boolean ipv6AddressesFirst(int lookupCharacteristics) {
 408         return (lookupCharacteristics & IPV6_FIRST) != 0;
 409     }
 410 
 411     // Native method to check if IPv4 is available
 412     private static native boolean isIPv4Available();
 413 
 414     /**
 415      * The {@code RuntimePermission("inetAddressResolverProvider")} is
 416      * necessary to subclass and instantiate the {@code InetAddressResolverProvider}
 417      * class, as well as to obtain resolver from an instance of that class,
 418      * and it is also required to obtain the operating system name resolution configurations.
 419      */
 420     private static final RuntimePermission INET_ADDRESS_RESOLVER_PERMISSION =
 421             new RuntimePermission("inetAddressResolverProvider");
 422 
 423     private static final ReentrantLock RESOLVER_LOCK = new ReentrantLock();
 424     private static volatile InetAddressResolver bootstrapResolver;
 425 
 426     @SuppressWarnings("removal")
 427     private static InetAddressResolver resolver() {
 428         InetAddressResolver cns = resolver;
 429         if (cns != null) {
 430             return cns;
 431         }
 432         if (VM.isBooted()) {
 433             RESOLVER_LOCK.lock();
 434             boolean bootstrapSet = false;
 435             try {
 436                 cns = resolver;
 437                 if (cns != null) {
 438                     return cns;
 439                 }
 440                 // Protection against provider calling InetAddress APIs during initialization
 441                 if (bootstrapResolver != null) {
 442                     return bootstrapResolver;
 443                 }
 444                 bootstrapResolver = BUILTIN_RESOLVER;
 445                 bootstrapSet = true;
 446 
 447                 if (HOSTS_FILE_NAME != null) {
 448                     // The default resolver service is already host file resolver
 449                     cns = BUILTIN_RESOLVER;
 450                 } else if (System.getSecurityManager() != null) {
 451                     PrivilegedAction<InetAddressResolver> pa = InetAddress::loadResolver;
 452                     cns = AccessController.doPrivileged(
 453                             pa, null, INET_ADDRESS_RESOLVER_PERMISSION);
 454                 } else {
 455                     cns = loadResolver();
 456                 }
 457 
 458                 InetAddress.resolver = cns;
 459                 return cns;
 460             } finally {
 461                 // We want to clear bootstrap resolver reference only after an attempt to
 462                 // instantiate a resolver has been completed.
 463                 if (bootstrapSet) {
 464                     bootstrapResolver = null;
 465                 }
 466                 RESOLVER_LOCK.unlock();
 467             }
 468         } else {
 469             return BUILTIN_RESOLVER;
 470         }
 471     }
 472 
 473     private static InetAddressResolver loadResolver() {
 474         return ServiceLoader.load(InetAddressResolverProvider.class)
 475                 .findFirst()
 476                 .map(nsp -> nsp.get(builtinConfiguration()))
 477                 .orElse(BUILTIN_RESOLVER);
 478     }
 479 
 480     private static InetAddressResolverProvider.Configuration builtinConfiguration() {
 481         return new ResolverProviderConfiguration(BUILTIN_RESOLVER, () -> {
 482             try {
 483                 return impl.getLocalHostName();
 484             } catch (UnknownHostException unknownHostException) {
 485                 return "localhost";
 486             }
 487         });
 488     }
 489 
 490     /**
 491      * Constructor for the Socket.accept() method.
 492      * This creates an empty InetAddress, which is filled in by
 493      * the accept() method.  This InetAddress, however, is not
 494      * put in the address cache, since it is not created by name.
 495      */
 496     InetAddress() {
 497         holder = new InetAddressHolder();
 498     }
 499 
 500     /**
 501      * Replaces the de-serialized object with an Inet4Address object.
 502      *
 503      * @return the alternate object to the de-serialized object.
 504      *
 505      * @throws ObjectStreamException if a new object replacing this
 506      * object could not be created
 507      */
 508     @java.io.Serial
 509     private Object readResolve() throws ObjectStreamException {
 510         // will replace the deserialized 'this' object
 511         return new Inet4Address(holder().getHostName(), holder().getAddress());
 512     }
 513 
 514     /**
 515      * Utility routine to check if the InetAddress is an
 516      * IP multicast address.
 517      * @return a {@code boolean} indicating if the InetAddress is
 518      * an IP multicast address
 519      * @since   1.1
 520      */
 521     public boolean isMulticastAddress() {
 522         return false;
 523     }
 524 
 525     /**
 526      * Utility routine to check if the InetAddress is a wildcard address.
 527      * @return a {@code boolean} indicating if the InetAddress is
 528      *         a wildcard address.
 529      * @since 1.4
 530      */
 531     public boolean isAnyLocalAddress() {
 532         return false;
 533     }
 534 
 535     /**
 536      * Utility routine to check if the InetAddress is a loopback address.
 537      *
 538      * @return a {@code boolean} indicating if the InetAddress is
 539      * a loopback address; or false otherwise.
 540      * @since 1.4
 541      */
 542     public boolean isLoopbackAddress() {
 543         return false;
 544     }
 545 
 546     /**
 547      * Utility routine to check if the InetAddress is a link local address.
 548      *
 549      * @return a {@code boolean} indicating if the InetAddress is
 550      * a link local address; or false if address is not a link local unicast address.
 551      * @since 1.4
 552      */
 553     public boolean isLinkLocalAddress() {
 554         return false;
 555     }
 556 
 557     /**
 558      * Utility routine to check if the InetAddress is a site local address.
 559      *
 560      * @return a {@code boolean} indicating if the InetAddress is
 561      * a site local address; or false if address is not a site local unicast address.
 562      * @since 1.4
 563      */
 564     public boolean isSiteLocalAddress() {
 565         return false;
 566     }
 567 
 568     /**
 569      * Utility routine to check if the multicast address has global scope.
 570      *
 571      * @return a {@code boolean} indicating if the address has
 572      *         is a multicast address of global scope, false if it is not
 573      *         of global scope or it is not a multicast address
 574      * @since 1.4
 575      */
 576     public boolean isMCGlobal() {
 577         return false;
 578     }
 579 
 580     /**
 581      * Utility routine to check if the multicast address has node scope.
 582      *
 583      * @return a {@code boolean} indicating if the address has
 584      *         is a multicast address of node-local scope, false if it is not
 585      *         of node-local scope or it is not a multicast address
 586      * @since 1.4
 587      */
 588     public boolean isMCNodeLocal() {
 589         return false;
 590     }
 591 
 592     /**
 593      * Utility routine to check if the multicast address has link scope.
 594      *
 595      * @return a {@code boolean} indicating if the address has
 596      *         is a multicast address of link-local scope, false if it is not
 597      *         of link-local scope or it is not a multicast address
 598      * @since 1.4
 599      */
 600     public boolean isMCLinkLocal() {
 601         return false;
 602     }
 603 
 604     /**
 605      * Utility routine to check if the multicast address has site scope.
 606      *
 607      * @return a {@code boolean} indicating if the address has
 608      *         is a multicast address of site-local scope, false if it is not
 609      *         of site-local scope or it is not a multicast address
 610      * @since 1.4
 611      */
 612     public boolean isMCSiteLocal() {
 613         return false;
 614     }
 615 
 616     /**
 617      * Utility routine to check if the multicast address has organization scope.
 618      *
 619      * @return a {@code boolean} indicating if the address has
 620      *         is a multicast address of organization-local scope,
 621      *         false if it is not of organization-local scope
 622      *         or it is not a multicast address
 623      * @since 1.4
 624      */
 625     public boolean isMCOrgLocal() {
 626         return false;
 627     }
 628 
 629 
 630     /**
 631      * Test whether that address is reachable. Best effort is made by the
 632      * implementation to try to reach the host, but firewalls and server
 633      * configuration may block requests resulting in an unreachable status
 634      * while some specific ports may be accessible.
 635      * A typical implementation will use ICMP ECHO REQUESTs if the
 636      * privilege can be obtained, otherwise it will try to establish
 637      * a TCP connection on port 7 (Echo) of the destination host.
 638      * <p>
 639      * The timeout value, in milliseconds, indicates the maximum amount of time
 640      * the try should take. If the operation times out before getting an
 641      * answer, the host is deemed unreachable. A negative value will result
 642      * in an IllegalArgumentException being thrown.
 643      *
 644      * @param   timeout the time, in milliseconds, before the call aborts
 645      * @return a {@code boolean} indicating if the address is reachable.
 646      * @throws IOException if a network error occurs
 647      * @throws  IllegalArgumentException if {@code timeout} is negative.
 648      * @since 1.5
 649      */
 650     public boolean isReachable(int timeout) throws IOException {
 651         return isReachable(null, 0 , timeout);
 652     }
 653 
 654     /**
 655      * Test whether that address is reachable. Best effort is made by the
 656      * implementation to try to reach the host, but firewalls and server
 657      * configuration may block requests resulting in a unreachable status
 658      * while some specific ports may be accessible.
 659      * A typical implementation will use ICMP ECHO REQUESTs if the
 660      * privilege can be obtained, otherwise it will try to establish
 661      * a TCP connection on port 7 (Echo) of the destination host.
 662      * <p>
 663      * The {@code network interface} and {@code ttl} parameters
 664      * let the caller specify which network interface the test will go through
 665      * and the maximum number of hops the packets should go through.
 666      * A negative value for the {@code ttl} will result in an
 667      * IllegalArgumentException being thrown.
 668      * <p>
 669      * The timeout value, in milliseconds, indicates the maximum amount of time
 670      * the try should take. If the operation times out before getting an
 671      * answer, the host is deemed unreachable. A negative value will result
 672      * in an IllegalArgumentException being thrown.
 673      *
 674      * @param   netif   the NetworkInterface through which the
 675      *                    test will be done, or null for any interface
 676      * @param   ttl     the maximum numbers of hops to try or 0 for the
 677      *                  default
 678      * @param   timeout the time, in milliseconds, before the call aborts
 679      * @throws  IllegalArgumentException if either {@code timeout}
 680      *                          or {@code ttl} are negative.
 681      * @return a {@code boolean} indicating if the address is reachable.
 682      * @throws IOException if a network error occurs
 683      * @since 1.5
 684      */
 685     public boolean isReachable(NetworkInterface netif, int ttl,
 686                                int timeout) throws IOException {
 687         if (ttl < 0)
 688             throw new IllegalArgumentException("ttl can't be negative");
 689         if (timeout < 0)
 690             throw new IllegalArgumentException("timeout can't be negative");
 691 
 692         return impl.isReachable(this, timeout, netif, ttl);
 693     }
 694 
 695     /**
 696      * Gets the host name for this IP address.
 697      *
 698      * <p>If this InetAddress was created with a host name,
 699      * this host name will be remembered and returned;
 700      * otherwise, a reverse name lookup will be performed
 701      * and the result will be returned based on the system
 702      * configured resolver. If a lookup of the name service
 703      * is required, call
 704      * {@link #getCanonicalHostName() getCanonicalHostName}.
 705      *
 706      * <p>If there is a security manager, its
 707      * {@code checkConnect} method is first called
 708      * with the hostname and {@code -1}
 709      * as its arguments to see if the operation is allowed.
 710      * If the operation is not allowed, it will return
 711      * the textual representation of the IP address.
 712      *
 713      * @return  the host name for this IP address, or if the operation
 714      *    is not allowed by the security check, the textual
 715      *    representation of the IP address.
 716      *
 717      * @see InetAddress#getCanonicalHostName
 718      * @see SecurityManager#checkConnect
 719      */
 720     public String getHostName() {
 721         return getHostName(true);
 722     }
 723 
 724     /**
 725      * Returns the hostname for this address.
 726      * If the host is equal to null, then this address refers to any
 727      * of the local machine's available network addresses.
 728      * this is package private so SocketPermission can make calls into
 729      * here without a security check.
 730      *
 731      * <p>If there is a security manager, this method first
 732      * calls its {@code checkConnect} method
 733      * with the hostname and {@code -1}
 734      * as its arguments to see if the calling code is allowed to know
 735      * the hostname for this IP address, i.e., to connect to the host.
 736      * If the operation is not allowed, it will return
 737      * the textual representation of the IP address.
 738      *
 739      * @return  the host name for this IP address, or if the operation
 740      *    is not allowed by the security check, the textual
 741      *    representation of the IP address.
 742      *
 743      * @param check make security check if true
 744      *
 745      * @see SecurityManager#checkConnect
 746      */
 747     String getHostName(boolean check) {
 748         if (holder().getHostName() == null) {
 749             holder().hostName = InetAddress.getHostFromNameService(this, check);
 750         }
 751         return holder().getHostName();
 752     }
 753 
 754     /**
 755      * Gets the fully qualified domain name for this IP address.
 756      * Best effort method, meaning we may not be able to return
 757      * the FQDN depending on the underlying system configuration.
 758      *
 759      * <p>If there is a security manager, this method first
 760      * calls its {@code checkConnect} method
 761      * with the hostname and {@code -1}
 762      * as its arguments to see if the calling code is allowed to know
 763      * the hostname for this IP address, i.e., to connect to the host.
 764      * If the operation is not allowed, it will return
 765      * the textual representation of the IP address.
 766      *
 767      * @return  the fully qualified domain name for this IP address,
 768      *    or if the operation is not allowed by the security check,
 769      *    the textual representation of the IP address.
 770      *
 771      * @see SecurityManager#checkConnect
 772      *
 773      * @since 1.4
 774      */
 775     public String getCanonicalHostName() {
 776         String value = canonicalHostName;
 777         if (value == null)
 778             canonicalHostName = value =
 779                 InetAddress.getHostFromNameService(this, true);
 780         return value;
 781     }
 782 
 783     /**
 784      * Returns the hostname for this address.
 785      *
 786      * <p>If there is a security manager, this method first
 787      * calls its {@code checkConnect} method
 788      * with the hostname and {@code -1}
 789      * as its arguments to see if the calling code is allowed to know
 790      * the hostname for this IP address, i.e., to connect to the host.
 791      * If the operation is not allowed, it will return
 792      * the textual representation of the IP address.
 793      *
 794      * @return  the host name for this IP address, or if the operation
 795      *    is not allowed by the security check, the textual
 796      *    representation of the IP address.
 797      *
 798      * @param check make security check if true
 799      *
 800      * @see SecurityManager#checkConnect
 801      */
 802     private static String getHostFromNameService(InetAddress addr, boolean check) {
 803         String host;
 804         var resolver = resolver();
 805         try {
 806             // first lookup the hostname
 807             host = resolver.lookupByAddress(addr.getAddress());
 808 
 809             /* check to see if calling code is allowed to know
 810              * the hostname for this IP address, ie, connect to the host
 811              */
 812             if (check) {
 813                 @SuppressWarnings("removal")
 814                 SecurityManager sec = System.getSecurityManager();
 815                 if (sec != null) {
 816                     sec.checkConnect(host, -1);
 817                 }
 818             }
 819 
 820             /* now get all the IP addresses for this hostname,
 821              * and make sure one of them matches the original IP
 822              * address. We do this to try and prevent spoofing.
 823              */
 824 
 825             InetAddress[] arr = InetAddress.getAllByName0(host, check);
 826             boolean ok = false;
 827 
 828             if (arr != null) {
 829                 for (int i = 0; !ok && i < arr.length; i++) {
 830                     ok = addr.equals(arr[i]);
 831                 }
 832             }
 833 
 834             //XXX: if it looks like a spoof just return the address?
 835             if (!ok) {
 836                 host = addr.getHostAddress();
 837                 return host;
 838             }
 839         // 'resolver.lookupByAddress' and 'InetAddress.getAllByName0' delegate to the system-wide resolver,
 840         // which could be a custom one. At that point we treat any unexpected RuntimeException thrown by
 841         // the resolver as we would treat an UnknownHostException or an unmatched host name.
 842         } catch (RuntimeException | UnknownHostException e) {
 843             host = addr.getHostAddress();



 844         }
 845         return host;
 846     }
 847 
 848     /**
 849      * Returns the raw IP address of this {@code InetAddress}
 850      * object. The result is in network byte order: the highest order
 851      * byte of the address is in {@code getAddress()[0]}.
 852      *
 853      * @return  the raw IP address of this object.
 854      */
 855     public byte[] getAddress() {
 856         return null;
 857     }
 858 
 859     /**
 860      * Returns the IP address string in textual presentation.
 861      *
 862      * @return  the raw IP address in a string format.
 863      * @since   1.0.2
 864      */
 865     public String getHostAddress() {
 866         return null;
 867      }
 868 
 869     /**
 870      * Returns a hashcode for this IP address.
 871      *
 872      * @return  a hash code value for this IP address.
 873      */
 874     public int hashCode() {
 875         return -1;
 876     }
 877 
 878     /**
 879      * Compares this object against the specified object.
 880      * The result is {@code true} if and only if the argument is
 881      * not {@code null} and it represents the same IP address as
 882      * this object.
 883      * <p>
 884      * Two instances of {@code InetAddress} represent the same IP
 885      * address if the length of the byte arrays returned by
 886      * {@code getAddress} is the same for both, and each of the
 887      * array components is the same for the byte arrays.
 888      *
 889      * @param   obj   the object to compare against.
 890      * @return  {@code true} if the objects are the same;
 891      *          {@code false} otherwise.
 892      * @see     java.net.InetAddress#getAddress()
 893      */
 894     public boolean equals(Object obj) {
 895         return false;
 896     }
 897 
 898     /**
 899      * Converts this IP address to a {@code String}. The
 900      * string returned is of the form: hostname / literal IP
 901      * address.
 902      *
 903      * If the host name is unresolved, no reverse lookup
 904      * is performed. The hostname part will be represented
 905      * by an empty string.
 906      *
 907      * @return  a string representation of this IP address.
 908      */
 909     public String toString() {
 910         String hostName = holder().getHostName();
 911         return Objects.toString(hostName, "")
 912             + "/" + getHostAddress();
 913     }
 914 
 915     // mapping from host name to Addresses - either NameServiceAddresses (while
 916     // still being looked-up by NameService(s)) or CachedAddresses when cached
 917     private static final ConcurrentMap<String, Addresses> cache =
 918         new ConcurrentHashMap<>();
 919 
 920     // CachedAddresses that have to expire are kept ordered in this NavigableSet
 921     // which is scanned on each access
 922     private static final NavigableSet<CachedAddresses> expirySet =
 923         new ConcurrentSkipListSet<>();
 924 
 925     // common interface
 926     private interface Addresses {
 927         InetAddress[] get() throws UnknownHostException;
 928     }
 929 
 930     // a holder for cached addresses with required metadata
 931     private static final class CachedAddresses  implements Addresses, Comparable<CachedAddresses> {
 932         private static final AtomicLong seq = new AtomicLong();
 933         final String host;
 934         final InetAddress[] inetAddresses;
 935         final long expiryTime; // time of expiry (in terms of System.nanoTime())
 936         final long id = seq.incrementAndGet(); // each instance is unique
 937 
 938         CachedAddresses(String host, InetAddress[] inetAddresses, long expiryTime) {
 939             this.host = host;
 940             this.inetAddresses = inetAddresses;
 941             this.expiryTime = expiryTime;
 942         }
 943 
 944         @Override
 945         public InetAddress[] get() throws UnknownHostException {
 946             if (inetAddresses == null) {
 947                 throw new UnknownHostException(host);
 948             }
 949             return inetAddresses;
 950         }
 951 
 952         @Override
 953         public int compareTo(CachedAddresses other) {
 954             // natural order is expiry time -
 955             // compare difference of expiry times rather than
 956             // expiry times directly, to avoid possible overflow.
 957             // (see System.nanoTime() recommendations...)
 958             long diff = this.expiryTime - other.expiryTime;
 959             if (diff < 0L) return -1;
 960             if (diff > 0L) return 1;
 961             // ties are broken using unique id
 962             return Long.compare(this.id, other.id);
 963         }
 964     }
 965 
 966     // a name service lookup based Addresses implementation which replaces itself
 967     // in cache when the result is obtained
 968     private static final class NameServiceAddresses implements Addresses {
 969         private final String host;

 970 
 971         NameServiceAddresses(String host) {
 972             this.host = host;

 973         }
 974 
 975         @Override
 976         public InetAddress[] get() throws UnknownHostException {
 977             Addresses addresses;
 978             // only one thread is doing lookup to name service
 979             // for particular host at any time.
 980             synchronized (this) {
 981                 // re-check that we are still us + re-install us if slot empty
 982                 addresses = cache.putIfAbsent(host, this);
 983                 if (addresses == null) {
 984                     // this can happen when we were replaced by CachedAddresses in
 985                     // some other thread, then CachedAddresses expired and were
 986                     // removed from cache while we were waiting for lock...
 987                     addresses = this;
 988                 }
 989                 // still us ?
 990                 if (addresses == this) {
 991                     // lookup name services
 992                     InetAddress[] inetAddresses;
 993                     UnknownHostException ex;
 994                     int cachePolicy;
 995                     try {
 996                         inetAddresses = getAddressesFromNameService(host);
 997                         ex = null;
 998                         cachePolicy = InetAddressCachePolicy.get();
 999                     } catch (UnknownHostException uhe) {
1000                         inetAddresses = null;
1001                         ex = uhe;
1002                         cachePolicy = InetAddressCachePolicy.getNegative();
1003                     }
1004                     // remove or replace us with cached addresses according to cachePolicy
1005                     if (cachePolicy == InetAddressCachePolicy.NEVER) {
1006                         cache.remove(host, this);
1007                     } else {
1008                         CachedAddresses cachedAddresses = new CachedAddresses(
1009                             host,
1010                             inetAddresses,
1011                             cachePolicy == InetAddressCachePolicy.FOREVER
1012                             ? 0L
1013                             // cachePolicy is in [s] - we need [ns]
1014                             : System.nanoTime() + 1000_000_000L * cachePolicy
1015                         );
1016                         if (cache.replace(host, this, cachedAddresses) &&
1017                             cachePolicy != InetAddressCachePolicy.FOREVER) {
1018                             // schedule expiry
1019                             expirySet.add(cachedAddresses);
1020                         }
1021                     }
1022                     if (inetAddresses == null || inetAddresses.length == 0) {
1023                         throw ex == null ? new UnknownHostException(host) : ex;
1024                     }
1025                     return inetAddresses;
1026                 }
1027                 // else addresses != this
1028             }
1029             // delegate to different addresses when we are already replaced
1030             // but outside of synchronized block to avoid any chance of dead-locking
1031             return addresses.get();
1032         }
1033     }
1034 
1035     /**
1036      * The default InetAddressResolver implementation, which delegates to the underlying































1037      * OS network libraries to resolve host address mappings.
1038      *
1039      * @since 9
1040      */
1041     private static final class PlatformResolver implements InetAddressResolver {
1042 
1043         public Stream<InetAddress> lookupByName(String host, LookupPolicy policy)
1044                 throws UnknownHostException {
1045             Objects.requireNonNull(host);
1046             Objects.requireNonNull(policy);
1047             return Arrays.stream(impl.lookupAllHostAddr(host, policy));
1048         }
1049 
1050         public String lookupByAddress(byte[] addr)
1051                 throws UnknownHostException {
1052             Objects.requireNonNull(addr);
1053             if (addr.length != Inet4Address.INADDRSZ && addr.length != Inet6Address.INADDRSZ) {
1054                 throw new IllegalArgumentException("Invalid address length");
1055             }
1056             return impl.getHostByAddr(addr);
1057         }
1058     }
1059 
1060     /**
1061      * The HostsFileResolver provides host address mapping
1062      * by reading the entries in a hosts file, which is specified by
1063      * {@code jdk.net.hosts.file} system property
1064      *
1065      * <p>The file format is that which corresponds with the /etc/hosts file
1066      * IP Address host alias list.
1067      *
1068      * <p>When the file lookup is enabled it replaces the default InetAddressResolver
1069      * implementation
1070      *
1071      * @since 9
1072      */
1073     private static final class HostsFileResolver implements InetAddressResolver {






1074 
1075         private final String hostsFile;
1076 
1077         public HostsFileResolver(String hostsFileName) {
1078             this.hostsFile = hostsFileName;
1079         }
1080 
1081         /**
1082          * Lookup the host name  corresponding to the IP address provided.
1083          * Search the configured host file a host name corresponding to
1084          * the specified IP address.
1085          *
1086          * @param addr byte array representing an IP address
1087          * @return {@code String} representing the host name mapping
1088          * @throws UnknownHostException if no host found for the specified IP address
1089          * @throws IllegalArgumentException if IP address is of illegal length
1090          */
1091         @Override
1092         public String lookupByAddress(byte[] addr) throws UnknownHostException {
1093             String hostEntry;
1094             String host = null;
1095             Objects.requireNonNull(addr);
1096             // Check the length of the address array
1097             if (addr.length != Inet4Address.INADDRSZ && addr.length != Inet6Address.INADDRSZ) {
1098                 throw new IllegalArgumentException("Invalid address length");
1099             }
1100 
1101             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
1102                                                         UTF_8.INSTANCE)) {

1103                 while (hostsFileScanner.hasNextLine()) {
1104                     hostEntry = hostsFileScanner.nextLine();
1105                     if (!hostEntry.startsWith("#")) {
1106                         hostEntry = removeComments(hostEntry);
1107                         String[] mapping = hostEntry.split("\\s+");
1108                         if (mapping.length >= 2 &&
1109                             Arrays.equals(addr, createAddressByteArray(mapping[0]))) {
1110                             host = mapping[1];
1111                             break;
1112                         }
1113                     }
1114                 }
1115             } catch (IOException e) {
1116                 throw new UnknownHostException("Unable to resolve address "
1117                         + Arrays.toString(addr) + " as hosts file " + hostsFile
1118                         + " not found ");
1119             }
1120 
1121             if ((host == null) || (host.isEmpty()) || (host.equals(" "))) {
1122                 throw new UnknownHostException("Requested address "
1123                         + Arrays.toString(addr)
1124                         + " resolves to an invalid entry in hosts file "
1125                         + hostsFile);
1126             }
1127             return host;
1128         }
1129 
1130         /**
1131          * <p>Lookup a host mapping by name. Retrieve the IP addresses
1132          * associated with a host.
1133          *
1134          * <p>Search the configured hosts file for the addresses associated
1135          * with the specified host name.
1136          *
1137          * @param host the specified hostname
1138          * @param lookupPolicy IP addresses lookup policy which specifies addresses
1139          *                     family and their order
1140          * @return stream of IP addresses for the requested host
1141          * @throws UnknownHostException
1142          *             if no IP address for the {@code host} could be found
1143          */
1144         public Stream<InetAddress> lookupByName(String host, LookupPolicy lookupPolicy)
1145                 throws UnknownHostException {
1146             String hostEntry;
1147             String addrStr;
1148             byte addr[];
1149 
1150             Objects.requireNonNull(host);
1151             Objects.requireNonNull(lookupPolicy);
1152             List<InetAddress> inetAddresses = new ArrayList<>();
1153             List<InetAddress> inet4Addresses = new ArrayList<>();
1154             List<InetAddress> inet6Addresses = new ArrayList<>();
1155             int flags = lookupPolicy.characteristics();
1156             boolean needIPv4 = (flags & IPv4) != 0;
1157             boolean needIPv6 = (flags & IPv6) != 0;
1158 
1159             // lookup the file and create a list InetAddress for the specified host
1160             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
1161                     UTF_8.INSTANCE)) {
1162                 while (hostsFileScanner.hasNextLine()) {
1163                     hostEntry = hostsFileScanner.nextLine();
1164                     if (!hostEntry.startsWith("#")) {
1165                         hostEntry = removeComments(hostEntry);
1166                         if (hostEntry.contains(host)) {
1167                             addrStr = extractHostAddr(hostEntry, host);
1168                             if ((addrStr != null) && (!addrStr.isEmpty())) {
1169                                 addr = createAddressByteArray(addrStr);
1170                                 if (addr != null) {
1171                                     InetAddress address = InetAddress.getByAddress(host, addr);
1172                                     inetAddresses.add(address);
1173                                     if (address instanceof Inet4Address && needIPv4) {
1174                                         inet4Addresses.add(address);
1175                                     }
1176                                     if (address instanceof Inet6Address && needIPv6) {
1177                                         inet6Addresses.add(address);
1178                                     }
1179                                 }
1180                             }
1181                         }
1182                     }
1183                 }
1184             } catch (IOException e) {
1185                 throw new UnknownHostException("Unable to resolve host " + host
1186                         + " as hosts file " + hostsFile + " not found ");
1187             }
1188             // Check if only IPv4 addresses are requested
1189             if (needIPv4 && !needIPv6) {
1190                 checkResultsList(inet4Addresses, host);
1191                 return inet4Addresses.stream();









1192             }
1193             // Check if only IPv6 addresses are requested
1194             if (!needIPv4 && needIPv6) {
1195                 checkResultsList(inet6Addresses, host);
1196                 return inet6Addresses.stream();
1197             }
1198             // If both type of addresses are requested:
1199             // First, check if there is any results. Then arrange
1200             // addresses according to LookupPolicy value.
1201             checkResultsList(inetAddresses, host);
1202             if (ipv6AddressesFirst(flags)) {
1203                 return Stream.concat(inet6Addresses.stream(), inet4Addresses.stream());
1204             } else if (ipv4AddressesFirst(flags)) {
1205                 return Stream.concat(inet4Addresses.stream(), inet6Addresses.stream());
1206             }
1207             // Only "system" addresses order is possible at this stage
1208             assert systemAddressesOrder(flags);
1209             return inetAddresses.stream();
1210         }
1211 
1212         // Checks if result list with addresses is not empty.
1213         // If it is empty throw an UnknownHostException.
1214         private void checkResultsList(List<InetAddress> addressesList, String hostName)
1215                 throws UnknownHostException {
1216             if (addressesList.isEmpty()) {
1217                 throw new UnknownHostException("Unable to resolve host " + hostName
1218                         + " in hosts file " + hostsFile);
1219             }
1220         }
1221 
1222         private String removeComments(String hostsEntry) {
1223             String filteredEntry = hostsEntry;
1224             int hashIndex;
1225 
1226             if ((hashIndex = hostsEntry.indexOf("#")) != -1) {
1227                 filteredEntry = hostsEntry.substring(0, hashIndex);
1228             }
1229             return filteredEntry;
1230         }
1231 
1232         private byte [] createAddressByteArray(String addrStr) {
1233             byte[] addrArray;
1234             // check if IPV4 address - most likely
1235             addrArray = IPAddressUtil.textToNumericFormatV4(addrStr);
1236             if (addrArray == null) {
1237                 addrArray = IPAddressUtil.textToNumericFormatV6(addrStr);
1238             }
1239             return addrArray;
1240         }
1241 
1242         /** host to ip address mapping */
1243         private String extractHostAddr(String hostEntry, String host) {
1244             String[] mapping = hostEntry.split("\\s+");
1245             String hostAddr = null;
1246 
1247             if (mapping.length >= 2) {
1248                 // look at the host aliases
1249                 for (int i = 1; i < mapping.length; i++) {
1250                     if (mapping[i].equalsIgnoreCase(host)) {
1251                         hostAddr = mapping[0];
1252                     }
1253                 }
1254             }
1255             return hostAddr;
1256         }
1257     }
1258 
1259     static final InetAddressImpl  impl;
1260 
1261     /**
1262      * Platform-wide {@code LookupPolicy} initialized from {@code "java.net.preferIPv4Stack"},
1263      * {@code "java.net.preferIPv6Addresses"} system properties.
1264      */
1265     static final LookupPolicy PLATFORM_LOOKUP_POLICY;
1266 
1267     static {
1268         // create the impl
1269         impl = InetAddressImplFactory.create();
1270 
1271         // impl must be initialized before calling this method
1272         PLATFORM_LOOKUP_POLICY = initializePlatformLookupPolicy();
1273 
1274         // create built-in resolver
1275         BUILTIN_RESOLVER = createBuiltinInetAddressResolver();
1276     }
1277 
1278     /**
1279      * Create an instance of the InetAddressResolver interface based on
1280      * the setting of the {@code jdk.net.hosts.file} system property.
1281      *
1282      * <p>The default InetAddressResolver is the PlatformResolver, which typically
1283      * delegates name and address resolution calls to the underlying
1284      * OS network libraries.
1285      *
1286      * <p> A HostsFileResolver is created if the {@code jdk.net.hosts.file}
1287      * system property is set. If the specified file doesn't exist, the name or
1288      * address lookup will result in an UnknownHostException. Thus, non existent
1289      * hosts file is handled as if the file is empty.
1290      *
1291      * @return an InetAddressResolver
1292      */
1293     private static InetAddressResolver createBuiltinInetAddressResolver() {
1294         InetAddressResolver theResolver;
1295         if (HOSTS_FILE_NAME != null) {
1296             theResolver = new HostsFileResolver(HOSTS_FILE_NAME);



1297         } else {
1298             theResolver = new PlatformResolver();
1299         }
1300         return theResolver;
1301     }
1302 
1303     /**
1304      * Creates an InetAddress based on the provided host name and IP address.
1305      * System {@linkplain InetAddressResolver resolver} is not used to check
1306      * the validity of the address.
1307      *
1308      * <p> The host name can either be a machine name, such as
1309      * "{@code www.example.com}", or a textual representation of its IP
1310      * address.
1311      * <p> No validity checking is done on the host name either.
1312      *
1313      * <p> If addr specifies an IPv4 address an instance of Inet4Address
1314      * will be returned; otherwise, an instance of Inet6Address
1315      * will be returned.
1316      *
1317      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1318      * must be 16 bytes long
1319      *
1320      * @param host the specified host
1321      * @param addr the raw IP address in network byte order
1322      * @return  an InetAddress object created from the raw IP address.
1323      * @throws     UnknownHostException  if IP address is of illegal length
1324      * @since 1.4
1325      */
1326     public static InetAddress getByAddress(String host, byte[] addr)
1327         throws UnknownHostException {
1328         if (host != null && !host.isEmpty() && host.charAt(0) == '[') {
1329             if (host.charAt(host.length()-1) == ']') {
1330                 host = host.substring(1, host.length() -1);
1331             }
1332         }
1333         if (addr != null) {
1334             if (addr.length == Inet4Address.INADDRSZ) {
1335                 return new Inet4Address(host, addr);
1336             } else if (addr.length == Inet6Address.INADDRSZ) {
1337                 byte[] newAddr
1338                     = IPAddressUtil.convertFromIPv4MappedAddress(addr);
1339                 if (newAddr != null) {
1340                     return new Inet4Address(host, newAddr);
1341                 } else {
1342                     return new Inet6Address(host, addr);
1343                 }
1344             }
1345         }
1346         throw new UnknownHostException("addr is of illegal length");
1347     }
1348 
1349 
1350     /**
1351      * Determines the IP address of a host, given the host's name.
1352      *
1353      * <p> The host name can either be a machine name, such as
1354      * "{@code www.example.com}", or a textual representation of its
1355      * IP address. If a literal IP address is supplied, only the
1356      * validity of the address format is checked.
1357      *
1358      * <p> For {@code host} specified in literal IPv6 address,
1359      * either the form defined in RFC 2732 or the literal IPv6 address
1360      * format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
1361      * supported. See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
1362      * scoped addresses.
1363      *
1364      * <p> If the host is {@code null} or {@code host.length()} is equal
1365      * to zero, then an {@code InetAddress} representing an address of the
1366      * loopback interface is returned.
1367      * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC&nbsp;3330</a>
1368      * section&nbsp;2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC&nbsp;2373</a>
1369      * section&nbsp;2.5.3.
1370      *
1371      * <p> If there is a security manager, and {@code host} is not {@code null}
1372      * or {@code host.length() } is not equal to zero, the security manager's
1373      * {@code checkConnect} method is called with the hostname and {@code -1}
1374      * as its arguments to determine if the operation is allowed.
1375      *
1376      * @param      host   the specified host, or {@code null}.
1377      * @return     an IP address for the given host name.
1378      * @throws     UnknownHostException  if no IP address for the
1379      *               {@code host} could be found, or if a scope_id was specified
1380      *               for a global IPv6 address.
1381      * @throws     SecurityException if a security manager exists
1382      *             and its checkConnect method doesn't allow the operation
1383      */
1384     public static InetAddress getByName(String host)
1385         throws UnknownHostException {
1386         return InetAddress.getAllByName(host)[0];
1387     }
1388 






1389     /**
1390      * Given the name of a host, returns an array of its IP addresses,
1391      * based on the configured system {@linkplain InetAddressResolver resolver}.
1392      *
1393      * <p> The host name can either be a machine name, such as
1394      * "{@code www.example.com}", or a textual representation of its IP
1395      * address. If a literal IP address is supplied, only the
1396      * validity of the address format is checked.
1397      *
1398      * <p> For {@code host} specified in <i>literal IPv6 address</i>,
1399      * either the form defined in RFC 2732 or the literal IPv6 address
1400      * format defined in RFC 2373 is accepted. A literal IPv6 address may
1401      * also be qualified by appending a scoped zone identifier or scope_id.
1402      * The syntax and usage of scope_ids is described
1403      * <a href="Inet6Address.html#scoped">here</a>.
1404      *
1405      * <p> If the host is {@code null} or {@code host.length()} is equal
1406      * to zero, then an {@code InetAddress} representing an address of the
1407      * loopback interface is returned.
1408      * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC&nbsp;3330</a>
1409      * section&nbsp;2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC&nbsp;2373</a>
1410      * section&nbsp;2.5.3. </p>
1411      *
1412      * <p> If there is a security manager, and {@code host} is not {@code null}
1413      * or {@code host.length() } is not equal to zero, the security manager's
1414      * {@code checkConnect} method is called with the hostname and {@code -1}
1415      * as its arguments to determine if the operation is allowed.
1416      *
1417      * @param      host   the name of the host, or {@code null}.
1418      * @return     an array of all the IP addresses for a given host name.
1419      *
1420      * @throws     UnknownHostException  if no IP address for the
1421      *               {@code host} could be found, or if a scope_id was specified
1422      *               for a global IPv6 address.
1423      * @throws     SecurityException  if a security manager exists and its
1424      *               {@code checkConnect} method doesn't allow the operation.
1425      *
1426      * @see SecurityManager#checkConnect
1427      */
1428     public static InetAddress[] getAllByName(String host)
1429         throws UnknownHostException {





1430 
1431         if (host == null || host.isEmpty()) {
1432             InetAddress[] ret = new InetAddress[1];
1433             ret[0] = impl.loopbackAddress();
1434             return ret;
1435         }
1436 
1437         boolean ipv6Expected = false;
1438         if (host.charAt(0) == '[') {
1439             // This is supposed to be an IPv6 literal
1440             if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1441                 host = host.substring(1, host.length() -1);
1442                 ipv6Expected = true;
1443             } else {
1444                 // This was supposed to be a IPv6 address, but it's not!
1445                 throw new UnknownHostException(host + ": invalid IPv6 address");
1446             }
1447         }
1448 
1449         // if host is an IP address, we won't do further lookup
1450         if (Character.digit(host.charAt(0), 16) != -1
1451             || (host.charAt(0) == ':')) {
1452             byte[] addr = null;
1453             int numericZone = -1;
1454             String ifname = null;
1455             // see if it is IPv4 address
1456             addr = IPAddressUtil.textToNumericFormatV4(host);
1457             if (addr == null) {
1458                 // This is supposed to be an IPv6 literal
1459                 // Check if a numeric or string zone id is present
1460                 int pos;
1461                 if ((pos=host.indexOf ('%')) != -1) {
1462                     numericZone = checkNumericZone (host);
1463                     if (numericZone == -1) { /* remainder of string must be an ifname */
1464                         ifname = host.substring (pos+1);
1465                     }
1466                 }
1467                 if ((addr = IPAddressUtil.textToNumericFormatV6(host)) == null && host.contains(":")) {
1468                     throw new UnknownHostException(host + ": invalid IPv6 address");
1469                 }
1470             } else if (ipv6Expected) {
1471                 // Means an IPv4 literal between brackets!
1472                 throw new UnknownHostException("["+host+"]");
1473             }
1474             InetAddress[] ret = new InetAddress[1];
1475             if(addr != null) {
1476                 if (addr.length == Inet4Address.INADDRSZ) {
1477                     ret[0] = new Inet4Address(null, addr);
1478                 } else {
1479                     if (ifname != null) {
1480                         ret[0] = new Inet6Address(null, addr, ifname);
1481                     } else {
1482                         ret[0] = new Inet6Address(null, addr, numericZone);
1483                     }
1484                 }
1485                 return ret;
1486             }
1487         } else if (ipv6Expected) {
1488             // We were expecting an IPv6 Literal, but got something else
1489             throw new UnknownHostException("["+host+"]");
1490         }
1491         return getAllByName0(host, true, true);
1492     }
1493 
1494     /**
1495      * Returns the loopback address.
1496      * <p>
1497      * The InetAddress returned will represent the IPv4
1498      * loopback address, 127.0.0.1, or the IPv6 loopback
1499      * address, ::1. The IPv4 loopback address returned
1500      * is only one of many in the form 127.*.*.*
1501      *
1502      * @return  the InetAddress loopback instance.
1503      * @since 1.7
1504      */
1505     public static InetAddress getLoopbackAddress() {
1506         return impl.loopbackAddress();
1507     }
1508 
1509 
1510     /**
1511      * check if the literal address string has %nn appended
1512      * returns -1 if not, or the numeric value otherwise.
1513      *
1514      * %nn may also be a string that represents the displayName of
1515      * a currently available NetworkInterface.
1516      */
1517     private static int checkNumericZone (String s) throws UnknownHostException {
1518         int percent = s.indexOf ('%');
1519         int slen = s.length();
1520         int digit, zone=0;
1521         if (percent == -1) {
1522             return -1;
1523         }
1524         for (int i=percent+1; i<slen; i++) {
1525             char c = s.charAt(i);
1526             if (c == ']') {
1527                 if (i == percent+1) {
1528                     /* empty per-cent field */
1529                     return -1;
1530                 }
1531                 break;
1532             }
1533             if ((digit = Character.digit (c, 10)) < 0) {
1534                 return -1;
1535             }
1536             zone = (zone * 10) + digit;
1537         }
1538         return zone;
1539     }
1540 






1541     /**
1542      * package private so SocketPermission can call it
1543      */
1544     static InetAddress[] getAllByName0 (String host, boolean check)
1545         throws UnknownHostException  {
1546         return getAllByName0(host, check, true);
1547     }
1548 
1549     /**
1550      * Designated lookup method.
1551      *
1552      * @param host host name to look up

1553      * @param check perform security check
1554      * @param useCache use cached value if not expired else always
1555      *                 perform name service lookup (and cache the result)
1556      * @return array of InetAddress(es)
1557      * @throws UnknownHostException if host name is not found
1558      */
1559     private static InetAddress[] getAllByName0(String host,

1560                                                boolean check,
1561                                                boolean useCache)
1562         throws UnknownHostException  {
1563 
1564         /* If it gets here it is presumed to be a hostname */
1565 
1566         /* make sure the connection to the host is allowed, before we
1567          * give out a hostname
1568          */
1569         if (check) {
1570             @SuppressWarnings("removal")
1571             SecurityManager security = System.getSecurityManager();
1572             if (security != null) {
1573                 security.checkConnect(host, -1);
1574             }
1575         }
1576 
1577         // remove expired addresses from cache - expirySet keeps them ordered
1578         // by expiry time so we only need to iterate the prefix of the NavigableSet...
1579         long now = System.nanoTime();
1580         for (CachedAddresses caddrs : expirySet) {
1581             // compare difference of time instants rather than
1582             // time instants directly, to avoid possible overflow.
1583             // (see System.nanoTime() recommendations...)
1584             if ((caddrs.expiryTime - now) < 0L) {
1585                 // ConcurrentSkipListSet uses weakly consistent iterator,
1586                 // so removing while iterating is OK...
1587                 if (expirySet.remove(caddrs)) {
1588                     // ... remove from cache
1589                     cache.remove(caddrs.host, caddrs);
1590                 }
1591             } else {
1592                 // we encountered 1st element that expires in future
1593                 break;
1594             }
1595         }
1596 
1597         // look-up or remove from cache
1598         Addresses addrs;
1599         if (useCache) {
1600             addrs = cache.get(host);
1601         } else {
1602             addrs = cache.remove(host);
1603             if (addrs != null) {
1604                 if (addrs instanceof CachedAddresses) {
1605                     // try removing from expirySet too if CachedAddresses
1606                     expirySet.remove(addrs);
1607                 }
1608                 addrs = null;
1609             }
1610         }
1611 
1612         if (addrs == null) {
1613             // create a NameServiceAddresses instance which will look up
1614             // the name service and install it within cache...
1615             Addresses oldAddrs = cache.putIfAbsent(
1616                 host,
1617                     addrs = new NameServiceAddresses(host)
1618             );
1619             if (oldAddrs != null) { // lost putIfAbsent race
1620                 addrs = oldAddrs;
1621             }
1622         }
1623 
1624         // ask Addresses to get an array of InetAddress(es) and clone it
1625         return addrs.get().clone();
1626     }
1627 
1628     static InetAddress[] getAddressesFromNameService(String host)
1629             throws UnknownHostException {
1630         Stream<InetAddress> addresses = null;
1631         UnknownHostException ex = null;
1632 
1633         var resolver = resolver();
1634         try {
1635             addresses = resolver.lookupByName(host, PLATFORM_LOOKUP_POLICY);
1636         } catch (RuntimeException | UnknownHostException x) {
1637             if (host.equalsIgnoreCase("localhost")) {
1638                 addresses = Stream.of(impl.loopbackAddress());
1639             } else if (x instanceof UnknownHostException uhe) {
1640                 ex = uhe;
1641             } else {
1642                 ex = new UnknownHostException();
1643                 ex.initCause(x);
1644             }
1645         }
1646         InetAddress[] result = addresses == null ? null
1647                 : addresses.toArray(InetAddress[]::new);
1648         if (result == null || result.length == 0) {
1649             throw ex == null ? new UnknownHostException(host) : ex;
1650         }
1651         return result;






















1652     }
1653 
1654     /**
1655      * Returns an {@code InetAddress} object given the raw IP address .
1656      * The argument is in network byte order: the highest order
1657      * byte of the address is in {@code getAddress()[0]}.
1658      *
1659      * <p> This method doesn't block, i.e. no reverse lookup is performed.

1660      *
1661      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1662      * must be 16 bytes long
1663      *
1664      * @param addr the raw IP address in network byte order
1665      * @return  an InetAddress object created from the raw IP address.
1666      * @throws     UnknownHostException  if IP address is of illegal length
1667      * @since 1.4
1668      */
1669     public static InetAddress getByAddress(byte[] addr)
1670         throws UnknownHostException {
1671         return getByAddress(null, addr);
1672     }
1673 
1674     private static final class CachedLocalHost {
1675         final String host;
1676         final InetAddress addr;
1677         final long expiryTime = System.nanoTime() + 5000_000_000L; // now + 5s;
1678 
1679         CachedLocalHost(String host, InetAddress addr) {
1680             this.host = host;
1681             this.addr = addr;
1682         }
1683     }
1684 
1685     private static volatile CachedLocalHost cachedLocalHost;
1686 
1687     /**
1688      * Returns the address of the local host. This is achieved by retrieving
1689      * the name of the host from the system, then resolving that name into
1690      * an {@code InetAddress}.
1691      *
1692      * <P>Note: The resolved address may be cached for a short period of time.
1693      * </P>
1694      *
1695      * <p>If there is a security manager, its
1696      * {@code checkConnect} method is called
1697      * with the local host name and {@code -1}
1698      * as its arguments to see if the operation is allowed.
1699      * If the operation is not allowed, an InetAddress representing
1700      * the loopback address is returned.
1701      *
1702      * @return     the address of the local host.
1703      *
1704      * @throws     UnknownHostException  if the local host name could not
1705      *             be resolved into an address.
1706      *
1707      * @see SecurityManager#checkConnect
1708      * @see java.net.InetAddress#getByName(java.lang.String)
1709      */
1710     public static InetAddress getLocalHost() throws UnknownHostException {
1711 
1712         @SuppressWarnings("removal")
1713         SecurityManager security = System.getSecurityManager();
1714         try {
1715             // is cached data still valid?
1716             CachedLocalHost clh = cachedLocalHost;
1717             if (clh != null && (clh.expiryTime - System.nanoTime()) >= 0L) {
1718                 if (security != null) {
1719                     security.checkConnect(clh.host, -1);
1720                 }
1721                 return clh.addr;
1722             }
1723 
1724             String local = impl.getLocalHostName();
1725 
1726             if (security != null) {
1727                 security.checkConnect(local, -1);
1728             }
1729 
1730             InetAddress localAddr;
1731             if (local.equals("localhost")) {
1732                 // shortcut for "localhost" host name
1733                 localAddr = impl.loopbackAddress();
1734             } else {
1735                 // call getAllByName0 without security checks and
1736                 // without using cached data
1737                 try {
1738                     localAddr = getAllByName0(local, false, false)[0];
1739                 } catch (UnknownHostException uhe) {
1740                     // Rethrow with a more informative error message.
1741                     UnknownHostException uhe2 =
1742                         new UnknownHostException(local + ": " +
1743                                                  uhe.getMessage());
1744                     uhe2.initCause(uhe);
1745                     throw uhe2;
1746                 }
1747             }
1748             cachedLocalHost = new CachedLocalHost(local, localAddr);
1749             return localAddr;
1750         } catch (java.lang.SecurityException e) {
1751             return impl.loopbackAddress();
1752         }
1753     }
1754 
1755     /**
1756      * Perform class load-time initializations.
1757      */
1758     private static native void init();
1759 
1760 
1761     /*
1762      * Returns the InetAddress representing anyLocalAddress
1763      * (typically 0.0.0.0 or ::0)
1764      */
1765     static InetAddress anyLocalAddress() {
1766         return impl.anyLocalAddress();
1767     }
1768 
1769     /**
1770      * Initializes an empty InetAddress.
1771      */
1772     @java.io.Serial
1773     private void readObjectNoData () {
1774         if (getClass().getClassLoader() != null) {
1775             throw new SecurityException ("invalid address type");
1776         }
1777     }
1778 
1779     private static final jdk.internal.misc.Unsafe UNSAFE
1780             = jdk.internal.misc.Unsafe.getUnsafe();
1781     private static final long FIELDS_OFFSET
1782             = UNSAFE.objectFieldOffset(InetAddress.class, "holder");
1783 
1784     /**
1785      * Restores the state of this object from the stream.
1786      *
1787      * @param  s the {@code ObjectInputStream} from which data is read
1788      * @throws IOException if an I/O error occurs
1789      * @throws ClassNotFoundException if a serialized class cannot be loaded
1790      */
1791     @java.io.Serial
1792     private void readObject (ObjectInputStream s) throws
1793                          IOException, ClassNotFoundException {
1794         if (getClass().getClassLoader() != null) {
1795             throw new SecurityException ("invalid address type");
1796         }
1797         GetField gf = s.readFields();
1798         String host = (String)gf.get("hostName", null);
1799         int address = gf.get("address", 0);
1800         int family = gf.get("family", 0);
1801         if (family != IPv4 && family != IPv6) {
1802             throw new InvalidObjectException("invalid address family type: " + family);
1803         }
1804         InetAddressHolder h = new InetAddressHolder(host, address, family);
1805         UNSAFE.putReference(this, FIELDS_OFFSET, h);
1806     }
1807 
1808     /* needed because the serializable fields no longer exist */
1809 
1810     /**
1811      * @serialField hostName String the hostname for this address
1812      * @serialField address int holds a 32-bit IPv4 address.
1813      * @serialField family int specifies the address family type, for instance,
1814      * {@code '1'} for IPv4 addresses, and {@code '2'} for IPv6 addresses.
1815      */
1816     @java.io.Serial
1817     private static final ObjectStreamField[] serialPersistentFields = {
1818         new ObjectStreamField("hostName", String.class),
1819         new ObjectStreamField("address", int.class),
1820         new ObjectStreamField("family", int.class),
1821     };
1822 
1823     /**
1824      * Writes the state of this object to the stream.
1825      *
1826      * @param  s the {@code ObjectOutputStream} to which data is written
1827      * @throws IOException if an I/O error occurs
1828      */
1829     @java.io.Serial
1830     private void writeObject (ObjectOutputStream s) throws
1831                         IOException {
1832         if (getClass().getClassLoader() != null) {
1833             throw new SecurityException ("invalid address type");
1834         }
1835         PutField pf = s.putFields();
1836         pf.put("hostName", holder().getHostName());
1837         pf.put("address", holder().getAddress());
1838         pf.put("family", holder().getFamily());
1839         s.writeFields();
1840     }
1841 }
1842 
1843 /*
1844  * Simple factory to create the impl
1845  */
1846 class InetAddressImplFactory {
1847 
1848     static InetAddressImpl create() {
1849         return isIPv6Supported() ?
1850                 new Inet6AddressImpl() : new Inet4AddressImpl();
1851     }
1852 
1853     static native boolean isIPv6Supported();
1854 }
--- EOF ---