1 /*
   2  * Copyright (c) 1995, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.net;
  27 
  28 import java.util.NavigableSet;
  29 import java.util.ArrayList;
  30 import java.util.Objects;
  31 import java.util.Scanner;
  32 import java.security.AccessController;
  33 import java.io.File;
  34 import java.io.FileNotFoundException;
  35 import java.io.ObjectStreamException;
  36 import java.io.ObjectStreamField;
  37 import java.io.IOException;
  38 import java.io.ObjectInputStream;
  39 import java.io.ObjectInputStream.GetField;
  40 import java.io.ObjectOutputStream;
  41 import java.io.ObjectOutputStream.PutField;
  42 import java.lang.annotation.Native;
  43 import java.util.concurrent.ConcurrentHashMap;
  44 import java.util.concurrent.ConcurrentMap;
  45 import java.util.concurrent.ConcurrentSkipListSet;
  46 import java.util.concurrent.atomic.AtomicLong;
  47 
  48 import jdk.internal.misc.JavaNetInetAddressAccess;
  49 import jdk.internal.misc.SharedSecrets;
  50 import sun.security.action.*;
  51 import sun.net.InetAddressCachePolicy;
  52 import sun.net.util.IPAddressUtil;
  53 
  54 /**
  55  * This class represents an Internet Protocol (IP) address.
  56  *
  57  * <p> An IP address is either a 32-bit or 128-bit unsigned number
  58  * used by IP, a lower-level protocol on which protocols like UDP and
  59  * TCP are built. The IP address architecture is defined by <a
  60  * href="http://www.ietf.org/rfc/rfc790.txt"><i>RFC&nbsp;790:
  61  * Assigned Numbers</i></a>, <a
  62  * href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC&nbsp;1918:
  63  * Address Allocation for Private Internets</i></a>, <a
  64  * href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC&nbsp;2365:
  65  * Administratively Scoped IP Multicast</i></a>, and <a
  66  * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC&nbsp;2373: IP
  67  * Version 6 Addressing Architecture</i></a>. An instance of an
  68  * InetAddress consists of an IP address and possibly its
  69  * corresponding host name (depending on whether it is constructed
  70  * with a host name or whether it has already done reverse host name
  71  * resolution).
  72  *
  73  * <h3> Address types </h3>
  74  *
  75  * <table class="striped" style="margin-left:2em">
  76  *   <caption style="display:none">Description of unicast and multicast address types</caption>
  77  *   <thead>
  78  *   <tr><th scope="col">Address Type</th><th scope="col">Description</th></tr>
  79  *   </thead>
  80  *   <tbody>
  81  *   <tr><th scope="row" style="vertical-align:top">unicast</th>
  82  *       <td>An identifier for a single interface. A packet sent to
  83  *         a unicast address is delivered to the interface identified by
  84  *         that address.
  85  *
  86  *         <p> The Unspecified Address -- Also called anylocal or wildcard
  87  *         address. It must never be assigned to any node. It indicates the
  88  *         absence of an address. One example of its use is as the target of
  89  *         bind, which allows a server to accept a client connection on any
  90  *         interface, in case the server host has multiple interfaces.
  91  *
  92  *         <p> The <i>unspecified</i> address must not be used as
  93  *         the destination address of an IP packet.
  94  *
  95  *         <p> The <i>Loopback</i> Addresses -- This is the address
  96  *         assigned to the loopback interface. Anything sent to this
  97  *         IP address loops around and becomes IP input on the local
  98  *         host. This address is often used when testing a
  99  *         client.</td></tr>
 100  *   <tr><th scope="row" style="vertical-align:top">multicast</th>
 101  *       <td>An identifier for a set of interfaces (typically belonging
 102  *         to different nodes). A packet sent to a multicast address is
 103  *         delivered to all interfaces identified by that address.</td></tr>
 104  * </tbody>
 105  * </table>
 106  *
 107  * <h4> IP address scope </h4>
 108  *
 109  * <p> <i>Link-local</i> addresses are designed to be used for addressing
 110  * on a single link for purposes such as auto-address configuration,
 111  * neighbor discovery, or when no routers are present.
 112  *
 113  * <p> <i>Site-local</i> addresses are designed to be used for addressing
 114  * inside of a site without the need for a global prefix.
 115  *
 116  * <p> <i>Global</i> addresses are unique across the internet.
 117  *
 118  * <h4> Textual representation of IP addresses </h4>
 119  *
 120  * The textual representation of an IP address is address family specific.
 121  *
 122  * <p>
 123  *
 124  * For IPv4 address format, please refer to <A
 125  * HREF="Inet4Address.html#format">Inet4Address#format</A>; For IPv6
 126  * address format, please refer to <A
 127  * HREF="Inet6Address.html#format">Inet6Address#format</A>.
 128  *
 129  * <P>There is a <a href="doc-files/net-properties.html#Ipv4IPv6">couple of
 130  * System Properties</a> affecting how IPv4 and IPv6 addresses are used.</P>
 131  *
 132  * <h4> Host Name Resolution </h4>
 133  *
 134  * Host name-to-IP address <i>resolution</i> is accomplished through
 135  * the use of a combination of local machine configuration information
 136  * and network naming services such as the Domain Name System (DNS)
 137  * and Network Information Service(NIS). The particular naming
 138  * services(s) being used is by default the local machine configured
 139  * one. For any host name, its corresponding IP address is returned.
 140  *
 141  * <p> <i>Reverse name resolution</i> means that for any IP address,
 142  * the host associated with the IP address is returned.
 143  *
 144  * <p> The InetAddress class provides methods to resolve host names to
 145  * their IP addresses and vice versa.
 146  *
 147  * <h4> InetAddress Caching </h4>
 148  *
 149  * The InetAddress class has a cache to store successful as well as
 150  * unsuccessful host name resolutions.
 151  *
 152  * <p> By default, when a security manager is installed, in order to
 153  * protect against DNS spoofing attacks,
 154  * the result of positive host name resolutions are
 155  * cached forever. When a security manager is not installed, the default
 156  * behavior is to cache entries for a finite (implementation dependent)
 157  * period of time. The result of unsuccessful host
 158  * name resolution is cached for a very short period of time (10
 159  * seconds) to improve performance.
 160  *
 161  * <p> If the default behavior is not desired, then a Java security property
 162  * can be set to a different Time-to-live (TTL) value for positive
 163  * caching. Likewise, a system admin can configure a different
 164  * negative caching TTL value when needed.
 165  *
 166  * <p> Two Java security properties control the TTL values used for
 167  *  positive and negative host name resolution caching:
 168  *
 169  * <dl style="margin-left:2em">
 170  * <dt><b>networkaddress.cache.ttl</b></dt>
 171  * <dd>Indicates the caching policy for successful name lookups from
 172  * the name service. The value is specified as an integer to indicate
 173  * the number of seconds to cache the successful lookup. The default
 174  * setting is to cache for an implementation specific period of time.
 175  * <p>
 176  * A value of -1 indicates "cache forever".
 177  * </dd>
 178  * <dt><b>networkaddress.cache.negative.ttl</b> (default: 10)</dt>
 179  * <dd>Indicates the caching policy for un-successful name lookups
 180  * from the name service. The value is specified as an integer to
 181  * indicate the number of seconds to cache the failure for
 182  * un-successful lookups.
 183  * <p>
 184  * A value of 0 indicates "never cache".
 185  * A value of -1 indicates "cache forever".
 186  * </dd>
 187  * </dl>
 188  *
 189  * @author  Chris Warth
 190  * @see     java.net.InetAddress#getByAddress(byte[])
 191  * @see     java.net.InetAddress#getByAddress(java.lang.String, byte[])
 192  * @see     java.net.InetAddress#getAllByName(java.lang.String)
 193  * @see     java.net.InetAddress#getByName(java.lang.String)
 194  * @see     java.net.InetAddress#getLocalHost()
 195  * @since 1.0
 196  */
 197 public
 198 class InetAddress implements java.io.Serializable {
 199 
 200     @Native static final int PREFER_IPV4_VALUE = 0;
 201     @Native static final int PREFER_IPV6_VALUE = 1;
 202     @Native static final int PREFER_SYSTEM_VALUE = 2;
 203 
 204     /**
 205      * Specify the address family: Internet Protocol, Version 4
 206      * @since 1.4
 207      */
 208     @Native static final int IPv4 = 1;
 209 
 210     /**
 211      * Specify the address family: Internet Protocol, Version 6
 212      * @since 1.4
 213      */
 214     @Native static final int IPv6 = 2;
 215 
 216     /* Specify address family preference */
 217     static transient final int preferIPv6Address;
 218 
 219     static class InetAddressHolder {
 220         /**
 221          * Reserve the original application specified hostname.
 222          *
 223          * The original hostname is useful for domain-based endpoint
 224          * identification (see RFC 2818 and RFC 6125).  If an address
 225          * was created with a raw IP address, a reverse name lookup
 226          * may introduce endpoint identification security issue via
 227          * DNS forging.
 228          *
 229          * Oracle JSSE provider is using this original hostname, via
 230          * jdk.internal.misc.JavaNetAccess, for SSL/TLS endpoint identification.
 231          *
 232          * Note: May define a new public method in the future if necessary.
 233          */
 234         String originalHostName;
 235 
 236         InetAddressHolder() {}
 237 
 238         InetAddressHolder(String hostName, int address, int family) {
 239             this.originalHostName = hostName;
 240             this.hostName = hostName;
 241             this.address = address;
 242             this.family = family;
 243         }
 244 
 245         void init(String hostName, int family) {
 246             this.originalHostName = hostName;
 247             this.hostName = hostName;
 248             if (family != -1) {
 249                 this.family = family;
 250             }
 251         }
 252 
 253         String hostName;
 254 
 255         String getHostName() {
 256             return hostName;
 257         }
 258 
 259         String getOriginalHostName() {
 260             return originalHostName;
 261         }
 262 
 263         /**
 264          * Holds a 32-bit IPv4 address.
 265          */
 266         int address;
 267 
 268         int getAddress() {
 269             return address;
 270         }
 271 
 272         /**
 273          * Specifies the address family type, for instance, '1' for IPv4
 274          * addresses, and '2' for IPv6 addresses.
 275          */
 276         int family;
 277 
 278         int getFamily() {
 279             return family;
 280         }
 281     }
 282 
 283     /* Used to store the serializable fields of InetAddress */
 284     final transient InetAddressHolder holder;
 285 
 286     InetAddressHolder holder() {
 287         return holder;
 288     }
 289 
 290     /* Used to store the name service provider */
 291     private static transient NameService nameService = null;
 292 
 293     /* Used to store the best available hostname */
 294     private transient String canonicalHostName = null;
 295 
 296     /** use serialVersionUID from JDK 1.0.2 for interoperability */
 297     private static final long serialVersionUID = 3286316764910316507L;
 298 
 299     /*
 300      * Load net library into runtime, and perform initializations.
 301      */
 302     static {
 303         String str = java.security.AccessController.doPrivileged(
 304                 new GetPropertyAction("java.net.preferIPv6Addresses"));
 305         if (str == null) {
 306             preferIPv6Address = PREFER_IPV4_VALUE;
 307         } else if (str.equalsIgnoreCase("true")) {
 308             preferIPv6Address = PREFER_IPV6_VALUE;
 309         } else if (str.equalsIgnoreCase("false")) {
 310             preferIPv6Address = PREFER_IPV4_VALUE;
 311         } else if (str.equalsIgnoreCase("system")) {
 312             preferIPv6Address = PREFER_SYSTEM_VALUE;
 313         } else {
 314             preferIPv6Address = PREFER_IPV4_VALUE;
 315         }
 316         AccessController.doPrivileged(
 317             new java.security.PrivilegedAction<>() {
 318                 public Void run() {
 319                     System.loadLibrary("net");
 320                     return null;
 321                 }
 322             });
 323         SharedSecrets.setJavaNetInetAddressAccess(
 324                 new JavaNetInetAddressAccess() {
 325                     public String getOriginalHostName(InetAddress ia) {
 326                         return ia.holder.getOriginalHostName();
 327                     }
 328 
 329                     public InetAddress getByName(String hostName,
 330                                                  InetAddress hostAddress)
 331                             throws UnknownHostException
 332                     {
 333                         return InetAddress.getByName(hostName, hostAddress);
 334                     }
 335                 }
 336         );
 337         init();
 338     }
 339 
 340     /**
 341      * Constructor for the Socket.accept() method.
 342      * This creates an empty InetAddress, which is filled in by
 343      * the accept() method.  This InetAddress, however, is not
 344      * put in the address cache, since it is not created by name.
 345      */
 346     InetAddress() {
 347         holder = new InetAddressHolder();
 348     }
 349 
 350     /**
 351      * Replaces the de-serialized object with an Inet4Address object.
 352      *
 353      * @return the alternate object to the de-serialized object.
 354      *
 355      * @throws ObjectStreamException if a new object replacing this
 356      * object could not be created
 357      */
 358     private Object readResolve() throws ObjectStreamException {
 359         // will replace the deserialized 'this' object
 360         return new Inet4Address(holder().getHostName(), holder().getAddress());
 361     }
 362 
 363     /**
 364      * Utility routine to check if the InetAddress is an
 365      * IP multicast address.
 366      * @return a {@code boolean} indicating if the InetAddress is
 367      * an IP multicast address
 368      * @since   1.1
 369      */
 370     public boolean isMulticastAddress() {
 371         return false;
 372     }
 373 
 374     /**
 375      * Utility routine to check if the InetAddress is a wildcard address.
 376      * @return a {@code boolean} indicating if the Inetaddress is
 377      *         a wildcard address.
 378      * @since 1.4
 379      */
 380     public boolean isAnyLocalAddress() {
 381         return false;
 382     }
 383 
 384     /**
 385      * Utility routine to check if the InetAddress is a loopback address.
 386      *
 387      * @return a {@code boolean} indicating if the InetAddress is
 388      * a loopback address; or false otherwise.
 389      * @since 1.4
 390      */
 391     public boolean isLoopbackAddress() {
 392         return false;
 393     }
 394 
 395     /**
 396      * Utility routine to check if the InetAddress is an link local address.
 397      *
 398      * @return a {@code boolean} indicating if the InetAddress is
 399      * a link local address; or false if address is not a link local unicast address.
 400      * @since 1.4
 401      */
 402     public boolean isLinkLocalAddress() {
 403         return false;
 404     }
 405 
 406     /**
 407      * Utility routine to check if the InetAddress is a site local address.
 408      *
 409      * @return a {@code boolean} indicating if the InetAddress is
 410      * a site local address; or false if address is not a site local unicast address.
 411      * @since 1.4
 412      */
 413     public boolean isSiteLocalAddress() {
 414         return false;
 415     }
 416 
 417     /**
 418      * Utility routine to check if the multicast address has global scope.
 419      *
 420      * @return a {@code boolean} indicating if the address has
 421      *         is a multicast address of global scope, false if it is not
 422      *         of global scope or it is not a multicast address
 423      * @since 1.4
 424      */
 425     public boolean isMCGlobal() {
 426         return false;
 427     }
 428 
 429     /**
 430      * Utility routine to check if the multicast address has node scope.
 431      *
 432      * @return a {@code boolean} indicating if the address has
 433      *         is a multicast address of node-local scope, false if it is not
 434      *         of node-local scope or it is not a multicast address
 435      * @since 1.4
 436      */
 437     public boolean isMCNodeLocal() {
 438         return false;
 439     }
 440 
 441     /**
 442      * Utility routine to check if the multicast address has link scope.
 443      *
 444      * @return a {@code boolean} indicating if the address has
 445      *         is a multicast address of link-local scope, false if it is not
 446      *         of link-local scope or it is not a multicast address
 447      * @since 1.4
 448      */
 449     public boolean isMCLinkLocal() {
 450         return false;
 451     }
 452 
 453     /**
 454      * Utility routine to check if the multicast address has site scope.
 455      *
 456      * @return a {@code boolean} indicating if the address has
 457      *         is a multicast address of site-local scope, false if it is not
 458      *         of site-local scope or it is not a multicast address
 459      * @since 1.4
 460      */
 461     public boolean isMCSiteLocal() {
 462         return false;
 463     }
 464 
 465     /**
 466      * Utility routine to check if the multicast address has organization scope.
 467      *
 468      * @return a {@code boolean} indicating if the address has
 469      *         is a multicast address of organization-local scope,
 470      *         false if it is not of organization-local scope
 471      *         or it is not a multicast address
 472      * @since 1.4
 473      */
 474     public boolean isMCOrgLocal() {
 475         return false;
 476     }
 477 
 478 
 479     /**
 480      * Test whether that address is reachable. Best effort is made by the
 481      * implementation to try to reach the host, but firewalls and server
 482      * configuration may block requests resulting in a unreachable status
 483      * while some specific ports may be accessible.
 484      * A typical implementation will use ICMP ECHO REQUESTs if the
 485      * privilege can be obtained, otherwise it will try to establish
 486      * a TCP connection on port 7 (Echo) of the destination host.
 487      * <p>
 488      * The timeout value, in milliseconds, indicates the maximum amount of time
 489      * the try should take. If the operation times out before getting an
 490      * answer, the host is deemed unreachable. A negative value will result
 491      * in an IllegalArgumentException being thrown.
 492      *
 493      * @param   timeout the time, in milliseconds, before the call aborts
 494      * @return a {@code boolean} indicating if the address is reachable.
 495      * @throws IOException if a network error occurs
 496      * @throws  IllegalArgumentException if {@code timeout} is negative.
 497      * @since 1.5
 498      */
 499     public boolean isReachable(int timeout) throws IOException {
 500         return isReachable(null, 0 , timeout);
 501     }
 502 
 503     /**
 504      * Test whether that address is reachable. Best effort is made by the
 505      * implementation to try to reach the host, but firewalls and server
 506      * configuration may block requests resulting in a unreachable status
 507      * while some specific ports may be accessible.
 508      * A typical implementation will use ICMP ECHO REQUESTs if the
 509      * privilege can be obtained, otherwise it will try to establish
 510      * a TCP connection on port 7 (Echo) of the destination host.
 511      * <p>
 512      * The {@code network interface} and {@code ttl} parameters
 513      * let the caller specify which network interface the test will go through
 514      * and the maximum number of hops the packets should go through.
 515      * A negative value for the {@code ttl} will result in an
 516      * IllegalArgumentException being thrown.
 517      * <p>
 518      * The timeout value, in milliseconds, indicates the maximum amount of time
 519      * the try should take. If the operation times out before getting an
 520      * answer, the host is deemed unreachable. A negative value will result
 521      * in an IllegalArgumentException being thrown.
 522      *
 523      * @param   netif   the NetworkInterface through which the
 524      *                    test will be done, or null for any interface
 525      * @param   ttl     the maximum numbers of hops to try or 0 for the
 526      *                  default
 527      * @param   timeout the time, in milliseconds, before the call aborts
 528      * @throws  IllegalArgumentException if either {@code timeout}
 529      *                          or {@code ttl} are negative.
 530      * @return a {@code boolean}indicating if the address is reachable.
 531      * @throws IOException if a network error occurs
 532      * @since 1.5
 533      */
 534     public boolean isReachable(NetworkInterface netif, int ttl,
 535                                int timeout) throws IOException {
 536         if (ttl < 0)
 537             throw new IllegalArgumentException("ttl can't be negative");
 538         if (timeout < 0)
 539             throw new IllegalArgumentException("timeout can't be negative");
 540 
 541         return impl.isReachable(this, timeout, netif, ttl);
 542     }
 543 
 544     /**
 545      * Gets the host name for this IP address.
 546      *
 547      * <p>If this InetAddress was created with a host name,
 548      * this host name will be remembered and returned;
 549      * otherwise, a reverse name lookup will be performed
 550      * and the result will be returned based on the system
 551      * configured name lookup service. If a lookup of the name service
 552      * is required, call
 553      * {@link #getCanonicalHostName() getCanonicalHostName}.
 554      *
 555      * <p>If there is a security manager, its
 556      * {@code checkConnect} method is first called
 557      * with the hostname and {@code -1}
 558      * as its arguments to see if the operation is allowed.
 559      * If the operation is not allowed, it will return
 560      * the textual representation of the IP address.
 561      *
 562      * @return  the host name for this IP address, or if the operation
 563      *    is not allowed by the security check, the textual
 564      *    representation of the IP address.
 565      *
 566      * @see InetAddress#getCanonicalHostName
 567      * @see SecurityManager#checkConnect
 568      */
 569     public String getHostName() {
 570         return getHostName(true);
 571     }
 572 
 573     /**
 574      * Returns the hostname for this address.
 575      * If the host is equal to null, then this address refers to any
 576      * of the local machine's available network addresses.
 577      * this is package private so SocketPermission can make calls into
 578      * here without a security check.
 579      *
 580      * <p>If there is a security manager, this method first
 581      * calls its {@code checkConnect} method
 582      * with the hostname and {@code -1}
 583      * as its arguments to see if the calling code is allowed to know
 584      * the hostname for this IP address, i.e., to connect to the host.
 585      * If the operation is not allowed, it will return
 586      * the textual representation of the IP address.
 587      *
 588      * @return  the host name for this IP address, or if the operation
 589      *    is not allowed by the security check, the textual
 590      *    representation of the IP address.
 591      *
 592      * @param check make security check if true
 593      *
 594      * @see SecurityManager#checkConnect
 595      */
 596     String getHostName(boolean check) {
 597         if (holder().getHostName() == null) {
 598             holder().hostName = InetAddress.getHostFromNameService(this, check);
 599         }
 600         return holder().getHostName();
 601     }
 602 
 603     /**
 604      * Gets the fully qualified domain name for this IP address.
 605      * Best effort method, meaning we may not be able to return
 606      * the FQDN depending on the underlying system configuration.
 607      *
 608      * <p>If there is a security manager, this method first
 609      * calls its {@code checkConnect} method
 610      * with the hostname and {@code -1}
 611      * as its arguments to see if the calling code is allowed to know
 612      * the hostname for this IP address, i.e., to connect to the host.
 613      * If the operation is not allowed, it will return
 614      * the textual representation of the IP address.
 615      *
 616      * @return  the fully qualified domain name for this IP address,
 617      *    or if the operation is not allowed by the security check,
 618      *    the textual representation of the IP address.
 619      *
 620      * @see SecurityManager#checkConnect
 621      *
 622      * @since 1.4
 623      */
 624     public String getCanonicalHostName() {
 625         if (canonicalHostName == null) {
 626             canonicalHostName =
 627                 InetAddress.getHostFromNameService(this, true);
 628         }
 629         return canonicalHostName;
 630     }
 631 
 632     /**
 633      * Returns the hostname for this address.
 634      *
 635      * <p>If there is a security manager, this method first
 636      * calls its {@code checkConnect} method
 637      * with the hostname and {@code -1}
 638      * as its arguments to see if the calling code is allowed to know
 639      * the hostname for this IP address, i.e., to connect to the host.
 640      * If the operation is not allowed, it will return
 641      * the textual representation of the IP address.
 642      *
 643      * @return  the host name for this IP address, or if the operation
 644      *    is not allowed by the security check, the textual
 645      *    representation of the IP address.
 646      *
 647      * @param check make security check if true
 648      *
 649      * @see SecurityManager#checkConnect
 650      */
 651     private static String getHostFromNameService(InetAddress addr, boolean check) {
 652         String host = null;
 653             try {
 654                 // first lookup the hostname
 655                 host = nameService.getHostByAddr(addr.getAddress());
 656 
 657                 /* check to see if calling code is allowed to know
 658                  * the hostname for this IP address, ie, connect to the host
 659                  */
 660                 if (check) {
 661                     SecurityManager sec = System.getSecurityManager();
 662                     if (sec != null) {
 663                         sec.checkConnect(host, -1);
 664                     }
 665                 }
 666 
 667                 /* now get all the IP addresses for this hostname,
 668                  * and make sure one of them matches the original IP
 669                  * address. We do this to try and prevent spoofing.
 670                  */
 671 
 672                 InetAddress[] arr = InetAddress.getAllByName0(host, check);
 673                 boolean ok = false;
 674 
 675                 if(arr != null) {
 676                     for(int i = 0; !ok && i < arr.length; i++) {
 677                         ok = addr.equals(arr[i]);
 678                     }
 679                 }
 680 
 681                 //XXX: if it looks a spoof just return the address?
 682                 if (!ok) {
 683                     host = addr.getHostAddress();
 684                     return host;
 685                 }
 686             } catch (SecurityException e) {
 687                 host = addr.getHostAddress();
 688             } catch (UnknownHostException e) {
 689                 host = addr.getHostAddress();
 690                 // let next provider resolve the hostname
 691             }
 692         return host;
 693     }
 694 
 695     /**
 696      * Returns the raw IP address of this {@code InetAddress}
 697      * object. The result is in network byte order: the highest order
 698      * byte of the address is in {@code getAddress()[0]}.
 699      *
 700      * @return  the raw IP address of this object.
 701      */
 702     public byte[] getAddress() {
 703         return null;
 704     }
 705 
 706     /**
 707      * Returns the IP address string in textual presentation.
 708      *
 709      * @return  the raw IP address in a string format.
 710      * @since   1.0.2
 711      */
 712     public String getHostAddress() {
 713         return null;
 714      }
 715 
 716     /**
 717      * Returns a hashcode for this IP address.
 718      *
 719      * @return  a hash code value for this IP address.
 720      */
 721     public int hashCode() {
 722         return -1;
 723     }
 724 
 725     /**
 726      * Compares this object against the specified object.
 727      * The result is {@code true} if and only if the argument is
 728      * not {@code null} and it represents the same IP address as
 729      * this object.
 730      * <p>
 731      * Two instances of {@code InetAddress} represent the same IP
 732      * address if the length of the byte arrays returned by
 733      * {@code getAddress} is the same for both, and each of the
 734      * array components is the same for the byte arrays.
 735      *
 736      * @param   obj   the object to compare against.
 737      * @return  {@code true} if the objects are the same;
 738      *          {@code false} otherwise.
 739      * @see     java.net.InetAddress#getAddress()
 740      */
 741     public boolean equals(Object obj) {
 742         return false;
 743     }
 744 
 745     /**
 746      * Converts this IP address to a {@code String}. The
 747      * string returned is of the form: hostname / literal IP
 748      * address.
 749      *
 750      * If the host name is unresolved, no reverse name service lookup
 751      * is performed. The hostname part will be represented by an empty string.
 752      *
 753      * @return  a string representation of this IP address.
 754      */
 755     public String toString() {
 756         String hostName = holder().getHostName();
 757         return Objects.toString(hostName, "")
 758             + "/" + getHostAddress();
 759     }
 760 
 761     // mapping from host name to Addresses - either NameServiceAddresses (while
 762     // still being looked-up by NameService(s)) or CachedAddresses when cached
 763     private static final ConcurrentMap<String, Addresses> cache =
 764         new ConcurrentHashMap<>();
 765 
 766     // CachedAddresses that have to expire are kept ordered in this NavigableSet
 767     // which is scanned on each access
 768     private static final NavigableSet<CachedAddresses> expirySet =
 769         new ConcurrentSkipListSet<>();
 770 
 771     // common interface
 772     private interface Addresses {
 773         InetAddress[] get() throws UnknownHostException;
 774     }
 775 
 776     // a holder for cached addresses with required metadata
 777     private static final class CachedAddresses  implements Addresses, Comparable<CachedAddresses> {
 778         private static final AtomicLong seq = new AtomicLong();
 779         final String host;
 780         final InetAddress[] inetAddresses;
 781         final long expiryTime; // time of expiry (in terms of System.nanoTime())
 782         final long id = seq.incrementAndGet(); // each instance is unique
 783 
 784         CachedAddresses(String host, InetAddress[] inetAddresses, long expiryTime) {
 785             this.host = host;
 786             this.inetAddresses = inetAddresses;
 787             this.expiryTime = expiryTime;
 788         }
 789 
 790         @Override
 791         public InetAddress[] get() throws UnknownHostException {
 792             if (inetAddresses == null) {
 793                 throw new UnknownHostException(host);
 794             }
 795             return inetAddresses;
 796         }
 797 
 798         @Override
 799         public int compareTo(CachedAddresses other) {
 800             // natural order is expiry time -
 801             // compare difference of expiry times rather than
 802             // expiry times directly, to avoid possible overflow.
 803             // (see System.nanoTime() recommendations...)
 804             long diff = this.expiryTime - other.expiryTime;
 805             if (diff < 0L) return -1;
 806             if (diff > 0L) return 1;
 807             // ties are broken using unique id
 808             return Long.compare(this.id, other.id);
 809         }
 810     }
 811 
 812     // a name service lookup based Addresses implementation which replaces itself
 813     // in cache when the result is obtained
 814     private static final class NameServiceAddresses implements Addresses {
 815         private final String host;
 816         private final InetAddress reqAddr;
 817 
 818         NameServiceAddresses(String host, InetAddress reqAddr) {
 819             this.host = host;
 820             this.reqAddr = reqAddr;
 821         }
 822 
 823         @Override
 824         public InetAddress[] get() throws UnknownHostException {
 825             Addresses addresses;
 826             // only one thread is doing lookup to name service
 827             // for particular host at any time.
 828             synchronized (this) {
 829                 // re-check that we are still us + re-install us if slot empty
 830                 addresses = cache.putIfAbsent(host, this);
 831                 if (addresses == null) {
 832                     // this can happen when we were replaced by CachedAddresses in
 833                     // some other thread, then CachedAddresses expired and were
 834                     // removed from cache while we were waiting for lock...
 835                     addresses = this;
 836                 }
 837                 // still us ?
 838                 if (addresses == this) {
 839                     // lookup name services
 840                     InetAddress[] inetAddresses;
 841                     UnknownHostException ex;
 842                     int cachePolicy;
 843                     try {
 844                         inetAddresses = getAddressesFromNameService(host, reqAddr);
 845                         ex = null;
 846                         cachePolicy = InetAddressCachePolicy.get();
 847                     } catch (UnknownHostException uhe) {
 848                         inetAddresses = null;
 849                         ex = uhe;
 850                         cachePolicy = InetAddressCachePolicy.getNegative();
 851                     }
 852                     // remove or replace us with cached addresses according to cachePolicy
 853                     if (cachePolicy == InetAddressCachePolicy.NEVER) {
 854                         cache.remove(host, this);
 855                     } else {
 856                         CachedAddresses cachedAddresses = new CachedAddresses(
 857                             host,
 858                             inetAddresses,
 859                             cachePolicy == InetAddressCachePolicy.FOREVER
 860                             ? 0L
 861                             // cachePolicy is in [s] - we need [ns]
 862                             : System.nanoTime() + 1000_000_000L * cachePolicy
 863                         );
 864                         if (cache.replace(host, this, cachedAddresses) &&
 865                             cachePolicy != InetAddressCachePolicy.FOREVER) {
 866                             // schedule expiry
 867                             expirySet.add(cachedAddresses);
 868                         }
 869                     }
 870                     if (inetAddresses == null) {
 871                         throw ex == null ? new UnknownHostException(host) : ex;
 872                     }
 873                     return inetAddresses;
 874                 }
 875                 // else addresses != this
 876             }
 877             // delegate to different addresses when we are already replaced
 878             // but outside of synchronized block to avoid any chance of dead-locking
 879             return addresses.get();
 880         }
 881     }
 882 
 883     /**
 884      * NameService provides host and address lookup service
 885      *
 886      * @since 9
 887      */
 888     private interface NameService {
 889 
 890         /**
 891          * Lookup a host mapping by name. Retrieve the IP addresses
 892          * associated with a host
 893          *
 894          * @param host the specified hostname
 895          * @return array of IP addresses for the requested host
 896          * @throws UnknownHostException
 897          *             if no IP address for the {@code host} could be found
 898          */
 899         InetAddress[] lookupAllHostAddr(String host)
 900                 throws UnknownHostException;
 901 
 902         /**
 903          * Lookup the host corresponding to the IP address provided
 904          *
 905          * @param addr byte array representing an IP address
 906          * @return {@code String} representing the host name mapping
 907          * @throws UnknownHostException
 908          *             if no host found for the specified IP address
 909          */
 910         String getHostByAddr(byte[] addr) throws UnknownHostException;
 911 
 912     }
 913 
 914     /**
 915      * The default NameService implementation, which delegates to the underlying
 916      * OS network libraries to resolve host address mappings.
 917      *
 918      * @since 9
 919      */
 920     private static final class PlatformNameService implements NameService {
 921 
 922         public InetAddress[] lookupAllHostAddr(String host)
 923             throws UnknownHostException
 924         {
 925             return impl.lookupAllHostAddr(host);
 926         }
 927 
 928         public String getHostByAddr(byte[] addr)
 929             throws UnknownHostException
 930         {
 931             return impl.getHostByAddr(addr);
 932         }
 933     }
 934 
 935     /**
 936      * The HostsFileNameService provides host address mapping
 937      * by reading the entries in a hosts file, which is specified by
 938      * {@code jdk.net.hosts.file} system property
 939      *
 940      * <p>The file format is that which corresponds with the /etc/hosts file
 941      * IP Address host alias list.
 942      *
 943      * <p>When the file lookup is enabled it replaces the default NameService
 944      * implementation
 945      *
 946      * @since 9
 947      */
 948     private static final class HostsFileNameService implements NameService {
 949 
 950         private final String hostsFile;
 951 
 952         public HostsFileNameService (String hostsFileName) {
 953             this.hostsFile = hostsFileName;
 954         }
 955 
 956         private  String addrToString(byte addr[]) {
 957           String stringifiedAddress = null;
 958 
 959             if (addr.length == Inet4Address.INADDRSZ) {
 960                 stringifiedAddress = Inet4Address.numericToTextFormat(addr);
 961             } else { // treat as an IPV6 jobby
 962                 byte[] newAddr
 963                     = IPAddressUtil.convertFromIPv4MappedAddress(addr);
 964                 if (newAddr != null) {
 965                    stringifiedAddress = Inet4Address.numericToTextFormat(addr);
 966                 } else {
 967                     stringifiedAddress = Inet6Address.numericToTextFormat(addr);
 968                 }
 969             }
 970             return stringifiedAddress;
 971         }
 972 
 973         /**
 974          * Lookup the host name  corresponding to the IP address provided.
 975          * Search the configured host file a host name corresponding to
 976          * the specified IP address.
 977          *
 978          * @param addr byte array representing an IP address
 979          * @return {@code String} representing the host name mapping
 980          * @throws UnknownHostException
 981          *             if no host found for the specified IP address
 982          */
 983         @Override
 984         public String getHostByAddr(byte[] addr) throws UnknownHostException {
 985             String hostEntry;
 986             String host = null;
 987 
 988             String addrString = addrToString(addr);
 989             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile), "UTF-8")) {
 990                 while (hostsFileScanner.hasNextLine()) {
 991                     hostEntry = hostsFileScanner.nextLine();
 992                     if (!hostEntry.startsWith("#")) {
 993                         hostEntry = removeComments(hostEntry);
 994                         if (hostEntry.contains(addrString)) {
 995                             host = extractHost(hostEntry, addrString);
 996                             if (host != null) {
 997                                 break;
 998                             }
 999                         }
1000                     }
1001                 }
1002             } catch (FileNotFoundException e) {
1003                 throw new UnknownHostException("Unable to resolve address "
1004                         + addrString + " as hosts file " + hostsFile
1005                         + " not found ");
1006             }
1007 
1008             if ((host == null) || (host.equals("")) || (host.equals(" "))) {
1009                 throw new UnknownHostException("Requested address "
1010                         + addrString
1011                         + " resolves to an invalid entry in hosts file "
1012                         + hostsFile);
1013             }
1014             return host;
1015         }
1016 
1017         /**
1018          * <p>Lookup a host mapping by name. Retrieve the IP addresses
1019          * associated with a host.
1020          *
1021          * <p>Search the configured hosts file for the addresses assocaited with
1022          * with the specified host name.
1023          *
1024          * @param host the specified hostname
1025          * @return array of IP addresses for the requested host
1026          * @throws UnknownHostException
1027          *             if no IP address for the {@code host} could be found
1028          */
1029         public InetAddress[] lookupAllHostAddr(String host)
1030                 throws UnknownHostException {
1031             String hostEntry;
1032             String addrStr = null;
1033             InetAddress[] res = null;
1034             byte addr[] = new byte[4];
1035             ArrayList<InetAddress> inetAddresses = null;
1036 
1037             // lookup the file and create a list InetAddress for the specfied host
1038             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile), "UTF-8")) {
1039                 while (hostsFileScanner.hasNextLine()) {
1040                     hostEntry = hostsFileScanner.nextLine();
1041                     if (!hostEntry.startsWith("#")) {
1042                         hostEntry = removeComments(hostEntry);
1043                         if (hostEntry.contains(host)) {
1044                             addrStr = extractHostAddr(hostEntry, host);
1045                             if ((addrStr != null) && (!addrStr.equals(""))) {
1046                                 addr = createAddressByteArray(addrStr);
1047                                 if (inetAddresses == null) {
1048                                     inetAddresses = new ArrayList<>(1);
1049                                 }
1050                                 if (addr != null) {
1051                                     inetAddresses.add(InetAddress.getByAddress(host, addr));
1052                                 }
1053                             }
1054                         }
1055                     }
1056                 }
1057             } catch (FileNotFoundException e) {
1058                 throw new UnknownHostException("Unable to resolve host " + host
1059                         + " as hosts file " + hostsFile + " not found ");
1060             }
1061 
1062             if (inetAddresses != null) {
1063                 res = inetAddresses.toArray(new InetAddress[inetAddresses.size()]);
1064             } else {
1065                 throw new UnknownHostException("Unable to resolve host " + host
1066                         + " in hosts file " + hostsFile);
1067             }
1068             return res;
1069         }
1070 
1071         private String removeComments(String hostsEntry) {
1072             String filteredEntry = hostsEntry;
1073             int hashIndex;
1074 
1075             if ((hashIndex = hostsEntry.indexOf("#")) != -1) {
1076                 filteredEntry = hostsEntry.substring(0, hashIndex);
1077             }
1078             return filteredEntry;
1079         }
1080 
1081         private byte [] createAddressByteArray(String addrStr) {
1082             byte[] addrArray;
1083             // check if IPV4 address - most likely
1084             addrArray = IPAddressUtil.textToNumericFormatV4(addrStr);
1085             if (addrArray == null) {
1086                 addrArray = IPAddressUtil.textToNumericFormatV6(addrStr);
1087             }
1088             return addrArray;
1089         }
1090 
1091         /** host to ip address mapping */
1092         private String extractHostAddr(String hostEntry, String host) {
1093             String[] mapping = hostEntry.split("\\s+");
1094             String hostAddr = null;
1095 
1096             if (mapping.length >= 2) {
1097                 // look at the host aliases
1098                 for (int i = 1; i < mapping.length; i++) {
1099                     if (mapping[i].equalsIgnoreCase(host)) {
1100                         hostAddr = mapping[0];
1101                     }
1102                 }
1103             }
1104             return hostAddr;
1105         }
1106 
1107         /**
1108          * IP Address to host mapping
1109          * use first host alias in list
1110          */
1111         private String extractHost(String hostEntry, String addrString) {
1112             String[] mapping = hostEntry.split("\\s+");
1113             String host = null;
1114 
1115             if (mapping.length >= 2) {
1116                 if (mapping[0].equalsIgnoreCase(addrString)) {
1117                     host = mapping[1];
1118                 }
1119             }
1120             return host;
1121         }
1122     }
1123 
1124     static final InetAddressImpl  impl;
1125 
1126     static {
1127         // create the impl
1128         impl = InetAddressImplFactory.create();
1129 
1130         // create name service
1131         nameService = createNameService();
1132         }
1133 
1134     /**
1135      * Create an instance of the NameService interface based on
1136      * the setting of the {@codejdk.net.hosts.file} system property.
1137      *
1138      * <p>The default NameService is the PlatformNameService, which typically
1139      * delegates name and address resolution calls to the underlying
1140      * OS network libraries.
1141      *
1142      * <p> A HostsFileNameService is created if the {@code jdk.net.hosts.file}
1143      * system property is set. If the specified file doesn't exist, the name or
1144      * address lookup will result in an UnknownHostException. Thus, non existent
1145      * hosts file is handled as if the file is empty.
1146      *
1147      * @return a NameService
1148      */
1149     private static NameService createNameService() {
1150 
1151         String hostsFileName =
1152                 GetPropertyAction.privilegedGetProperty("jdk.net.hosts.file");
1153         NameService theNameService;
1154         if (hostsFileName != null) {
1155             theNameService = new HostsFileNameService(hostsFileName);
1156         } else {
1157             theNameService = new PlatformNameService();
1158         }
1159         return theNameService;
1160     }
1161 
1162     /**
1163      * Creates an InetAddress based on the provided host name and IP address.
1164      * No name service is checked for the validity of the address.
1165      *
1166      * <p> The host name can either be a machine name, such as
1167      * "{@code java.sun.com}", or a textual representation of its IP
1168      * address.
1169      * <p> No validity checking is done on the host name either.
1170      *
1171      * <p> If addr specifies an IPv4 address an instance of Inet4Address
1172      * will be returned; otherwise, an instance of Inet6Address
1173      * will be returned.
1174      *
1175      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1176      * must be 16 bytes long
1177      *
1178      * @param host the specified host
1179      * @param addr the raw IP address in network byte order
1180      * @return  an InetAddress object created from the raw IP address.
1181      * @exception  UnknownHostException  if IP address is of illegal length
1182      * @since 1.4
1183      */
1184     public static InetAddress getByAddress(String host, byte[] addr)
1185         throws UnknownHostException {
1186         if (host != null && host.length() > 0 && host.charAt(0) == '[') {
1187             if (host.charAt(host.length()-1) == ']') {
1188                 host = host.substring(1, host.length() -1);
1189             }
1190         }
1191         if (addr != null) {
1192             if (addr.length == Inet4Address.INADDRSZ) {
1193                 return new Inet4Address(host, addr);
1194             } else if (addr.length == Inet6Address.INADDRSZ) {
1195                 byte[] newAddr
1196                     = IPAddressUtil.convertFromIPv4MappedAddress(addr);
1197                 if (newAddr != null) {
1198                     return new Inet4Address(host, newAddr);
1199                 } else {
1200                     return new Inet6Address(host, addr);
1201                 }
1202             }
1203         }
1204         throw new UnknownHostException("addr is of illegal length");
1205     }
1206 
1207 
1208     /**
1209      * Determines the IP address of a host, given the host's name.
1210      *
1211      * <p> The host name can either be a machine name, such as
1212      * "{@code java.sun.com}", or a textual representation of its
1213      * IP address. If a literal IP address is supplied, only the
1214      * validity of the address format is checked.
1215      *
1216      * <p> For {@code host} specified in literal IPv6 address,
1217      * either the form defined in RFC 2732 or the literal IPv6 address
1218      * format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
1219      * supported. See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
1220      * scoped addresses.
1221      *
1222      * <p> If the host is {@code null} then an {@code InetAddress}
1223      * representing an address of the loopback interface is returned.
1224      * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC&nbsp;3330</a>
1225      * section&nbsp;2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC&nbsp;2373</a>
1226      * section&nbsp;2.5.3. </p>
1227      *
1228      * @param      host   the specified host, or {@code null}.
1229      * @return     an IP address for the given host name.
1230      * @exception  UnknownHostException  if no IP address for the
1231      *               {@code host} could be found, or if a scope_id was specified
1232      *               for a global IPv6 address.
1233      * @exception  SecurityException if a security manager exists
1234      *             and its checkConnect method doesn't allow the operation
1235      */
1236     public static InetAddress getByName(String host)
1237         throws UnknownHostException {
1238         return InetAddress.getAllByName(host)[0];
1239     }
1240 
1241     // called from deployment cache manager
1242     private static InetAddress getByName(String host, InetAddress reqAddr)
1243         throws UnknownHostException {
1244         return InetAddress.getAllByName(host, reqAddr)[0];
1245     }
1246 
1247     /**
1248      * Given the name of a host, returns an array of its IP addresses,
1249      * based on the configured name service on the system.
1250      *
1251      * <p> The host name can either be a machine name, such as
1252      * "{@code java.sun.com}", or a textual representation of its IP
1253      * address. If a literal IP address is supplied, only the
1254      * validity of the address format is checked.
1255      *
1256      * <p> For {@code host} specified in <i>literal IPv6 address</i>,
1257      * either the form defined in RFC 2732 or the literal IPv6 address
1258      * format defined in RFC 2373 is accepted. A literal IPv6 address may
1259      * also be qualified by appending a scoped zone identifier or scope_id.
1260      * The syntax and usage of scope_ids is described
1261      * <a href="Inet6Address.html#scoped">here</a>.
1262      * <p> If the host is {@code null} then an {@code InetAddress}
1263      * representing an address of the loopback interface is returned.
1264      * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC&nbsp;3330</a>
1265      * section&nbsp;2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC&nbsp;2373</a>
1266      * section&nbsp;2.5.3. </p>
1267      *
1268      * <p> If there is a security manager and {@code host} is not
1269      * null and {@code host.length() } is not equal to zero, the
1270      * security manager's
1271      * {@code checkConnect} method is called
1272      * with the hostname and {@code -1}
1273      * as its arguments to see if the operation is allowed.
1274      *
1275      * @param      host   the name of the host, or {@code null}.
1276      * @return     an array of all the IP addresses for a given host name.
1277      *
1278      * @exception  UnknownHostException  if no IP address for the
1279      *               {@code host} could be found, or if a scope_id was specified
1280      *               for a global IPv6 address.
1281      * @exception  SecurityException  if a security manager exists and its
1282      *               {@code checkConnect} method doesn't allow the operation.
1283      *
1284      * @see SecurityManager#checkConnect
1285      */
1286     public static InetAddress[] getAllByName(String host)
1287         throws UnknownHostException {
1288         return getAllByName(host, null);
1289     }
1290 
1291     private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
1292         throws UnknownHostException {
1293 
1294         if (host == null || host.length() == 0) {
1295             InetAddress[] ret = new InetAddress[1];
1296             ret[0] = impl.loopbackAddress();
1297             return ret;
1298         }
1299 
1300         boolean ipv6Expected = false;
1301         if (host.charAt(0) == '[') {
1302             // This is supposed to be an IPv6 literal
1303             if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1304                 host = host.substring(1, host.length() -1);
1305                 ipv6Expected = true;
1306             } else {
1307                 // This was supposed to be a IPv6 address, but it's not!
1308                 throw new UnknownHostException(host + ": invalid IPv6 address");
1309             }
1310         }
1311 
1312         // if host is an IP address, we won't do further lookup
1313         if (Character.digit(host.charAt(0), 16) != -1
1314             || (host.charAt(0) == ':')) {
1315             byte[] addr = null;
1316             int numericZone = -1;
1317             String ifname = null;
1318             // see if it is IPv4 address
1319             addr = IPAddressUtil.textToNumericFormatV4(host);
1320             if (addr == null) {
1321                 // This is supposed to be an IPv6 literal
1322                 // Check if a numeric or string zone id is present
1323                 int pos;
1324                 if ((pos=host.indexOf ('%')) != -1) {
1325                     numericZone = checkNumericZone (host);
1326                     if (numericZone == -1) { /* remainder of string must be an ifname */
1327                         ifname = host.substring (pos+1);
1328                     }
1329                 }
1330                 if ((addr = IPAddressUtil.textToNumericFormatV6(host)) == null && host.contains(":")) {
1331                     throw new UnknownHostException(host + ": invalid IPv6 address");
1332                 }
1333             } else if (ipv6Expected) {
1334                 // Means an IPv4 litteral between brackets!
1335                 throw new UnknownHostException("["+host+"]");
1336             }
1337             InetAddress[] ret = new InetAddress[1];
1338             if(addr != null) {
1339                 if (addr.length == Inet4Address.INADDRSZ) {
1340                     ret[0] = new Inet4Address(null, addr);
1341                 } else {
1342                     if (ifname != null) {
1343                         ret[0] = new Inet6Address(null, addr, ifname);
1344                     } else {
1345                         ret[0] = new Inet6Address(null, addr, numericZone);
1346                     }
1347                 }
1348                 return ret;
1349             }
1350         } else if (ipv6Expected) {
1351             // We were expecting an IPv6 Litteral, but got something else
1352             throw new UnknownHostException("["+host+"]");
1353         }
1354         return getAllByName0(host, reqAddr, true, true);
1355     }
1356 
1357     /**
1358      * Returns the loopback address.
1359      * <p>
1360      * The InetAddress returned will represent the IPv4
1361      * loopback address, 127.0.0.1, or the IPv6 loopback
1362      * address, ::1. The IPv4 loopback address returned
1363      * is only one of many in the form 127.*.*.*
1364      *
1365      * @return  the InetAddress loopback instance.
1366      * @since 1.7
1367      */
1368     public static InetAddress getLoopbackAddress() {
1369         return impl.loopbackAddress();
1370     }
1371 
1372 
1373     /**
1374      * check if the literal address string has %nn appended
1375      * returns -1 if not, or the numeric value otherwise.
1376      *
1377      * %nn may also be a string that represents the displayName of
1378      * a currently available NetworkInterface.
1379      */
1380     private static int checkNumericZone (String s) throws UnknownHostException {
1381         int percent = s.indexOf ('%');
1382         int slen = s.length();
1383         int digit, zone=0;
1384         if (percent == -1) {
1385             return -1;
1386         }
1387         for (int i=percent+1; i<slen; i++) {
1388             char c = s.charAt(i);
1389             if (c == ']') {
1390                 if (i == percent+1) {
1391                     /* empty per-cent field */
1392                     return -1;
1393                 }
1394                 break;
1395             }
1396             if ((digit = Character.digit (c, 10)) < 0) {
1397                 return -1;
1398             }
1399             zone = (zone * 10) + digit;
1400         }
1401         return zone;
1402     }
1403 
1404     private static InetAddress[] getAllByName0 (String host)
1405         throws UnknownHostException
1406     {
1407         return getAllByName0(host, true);
1408     }
1409 
1410     /**
1411      * package private so SocketPermission can call it
1412      */
1413     static InetAddress[] getAllByName0 (String host, boolean check)
1414         throws UnknownHostException  {
1415         return getAllByName0 (host, null, check, true);
1416     }
1417 
1418     /**
1419      * Designated lookup method.
1420      *
1421      * @param host host name to look up
1422      * @param reqAddr requested address to be the 1st in returned array
1423      * @param check perform security check
1424      * @param useCache use cached value if not expired else always
1425      *                 perform name service lookup (and cache the result)
1426      * @return array of InetAddress(es)
1427      * @throws UnknownHostException if host name is not found
1428      */
1429     private static InetAddress[] getAllByName0(String host,
1430                                                InetAddress reqAddr,
1431                                                boolean check,
1432                                                boolean useCache)
1433         throws UnknownHostException  {
1434 
1435         /* If it gets here it is presumed to be a hostname */
1436 
1437         /* make sure the connection to the host is allowed, before we
1438          * give out a hostname
1439          */
1440         if (check) {
1441             SecurityManager security = System.getSecurityManager();
1442             if (security != null) {
1443                 security.checkConnect(host, -1);
1444             }
1445         }
1446 
1447         // remove expired addresses from cache - expirySet keeps them ordered
1448         // by expiry time so we only need to iterate the prefix of the NavigableSet...
1449         long now = System.nanoTime();
1450         for (CachedAddresses caddrs : expirySet) {
1451             // compare difference of time instants rather than
1452             // time instants directly, to avoid possible overflow.
1453             // (see System.nanoTime() recommendations...)
1454             if ((caddrs.expiryTime - now) < 0L) {
1455                 // ConcurrentSkipListSet uses weakly consistent iterator,
1456                 // so removing while iterating is OK...
1457                 if (expirySet.remove(caddrs)) {
1458                     // ... remove from cache
1459                     cache.remove(caddrs.host, caddrs);
1460                 }
1461             } else {
1462                 // we encountered 1st element that expires in future
1463                 break;
1464             }
1465         }
1466 
1467         // look-up or remove from cache
1468         Addresses addrs;
1469         if (useCache) {
1470             addrs = cache.get(host);
1471         } else {
1472             addrs = cache.remove(host);
1473             if (addrs != null) {
1474                 if (addrs instanceof CachedAddresses) {
1475                     // try removing from expirySet too if CachedAddresses
1476                     expirySet.remove(addrs);
1477                 }
1478                 addrs = null;
1479             }
1480         }
1481 
1482         if (addrs == null) {
1483             // create a NameServiceAddresses instance which will look up
1484             // the name service and install it within cache...
1485             Addresses oldAddrs = cache.putIfAbsent(
1486                 host,
1487                 addrs = new NameServiceAddresses(host, reqAddr)
1488             );
1489             if (oldAddrs != null) { // lost putIfAbsent race
1490                 addrs = oldAddrs;
1491             }
1492         }
1493 
1494         // ask Addresses to get an array of InetAddress(es) and clone it
1495         return addrs.get().clone();
1496     }
1497 
1498     static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
1499         throws UnknownHostException
1500     {
1501         InetAddress[] addresses = null;
1502         UnknownHostException ex = null;
1503 
1504             try {
1505                 addresses = nameService.lookupAllHostAddr(host);
1506             } catch (UnknownHostException uhe) {
1507                 if (host.equalsIgnoreCase("localhost")) {
1508                     addresses = new InetAddress[] { impl.loopbackAddress() };
1509                 }
1510                 else {
1511                     ex = uhe;
1512                 }
1513             }
1514 
1515         if (addresses == null) {
1516             throw ex == null ? new UnknownHostException(host) : ex;
1517         }
1518 
1519         // More to do?
1520         if (reqAddr != null && addresses.length > 1 && !addresses[0].equals(reqAddr)) {
1521             // Find it?
1522             int i = 1;
1523             for (; i < addresses.length; i++) {
1524                 if (addresses[i].equals(reqAddr)) {
1525                     break;
1526                 }
1527             }
1528             // Rotate
1529             if (i < addresses.length) {
1530                 InetAddress tmp, tmp2 = reqAddr;
1531                 for (int j = 0; j < i; j++) {
1532                     tmp = addresses[j];
1533                     addresses[j] = tmp2;
1534                     tmp2 = tmp;
1535                 }
1536                 addresses[i] = tmp2;
1537             }
1538         }
1539 
1540         return addresses;
1541     }
1542 
1543     /**
1544      * Returns an {@code InetAddress} object given the raw IP address .
1545      * The argument is in network byte order: the highest order
1546      * byte of the address is in {@code getAddress()[0]}.
1547      *
1548      * <p> This method doesn't block, i.e. no reverse name service lookup
1549      * is performed.
1550      *
1551      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1552      * must be 16 bytes long
1553      *
1554      * @param addr the raw IP address in network byte order
1555      * @return  an InetAddress object created from the raw IP address.
1556      * @exception  UnknownHostException  if IP address is of illegal length
1557      * @since 1.4
1558      */
1559     public static InetAddress getByAddress(byte[] addr)
1560         throws UnknownHostException {
1561         return getByAddress(null, addr);
1562     }
1563 
1564     private static final class CachedLocalHost {
1565         final String host;
1566         final InetAddress addr;
1567         final long expiryTime = System.nanoTime() + 5000_000_000L; // now + 5s;
1568 
1569         CachedLocalHost(String host, InetAddress addr) {
1570             this.host = host;
1571             this.addr = addr;
1572         }
1573     }
1574 
1575     private static volatile CachedLocalHost cachedLocalHost;
1576 
1577     /**
1578      * Returns the address of the local host. This is achieved by retrieving
1579      * the name of the host from the system, then resolving that name into
1580      * an {@code InetAddress}.
1581      *
1582      * <P>Note: The resolved address may be cached for a short period of time.
1583      * </P>
1584      *
1585      * <p>If there is a security manager, its
1586      * {@code checkConnect} method is called
1587      * with the local host name and {@code -1}
1588      * as its arguments to see if the operation is allowed.
1589      * If the operation is not allowed, an InetAddress representing
1590      * the loopback address is returned.
1591      *
1592      * @return     the address of the local host.
1593      *
1594      * @exception  UnknownHostException  if the local host name could not
1595      *             be resolved into an address.
1596      *
1597      * @see SecurityManager#checkConnect
1598      * @see java.net.InetAddress#getByName(java.lang.String)
1599      */
1600     public static InetAddress getLocalHost() throws UnknownHostException {
1601 
1602         SecurityManager security = System.getSecurityManager();
1603         try {
1604             // is cached data still valid?
1605             CachedLocalHost clh = cachedLocalHost;
1606             if (clh != null && (clh.expiryTime - System.nanoTime()) >= 0L) {
1607                 if (security != null) {
1608                     security.checkConnect(clh.host, -1);
1609                 }
1610                 return clh.addr;
1611             }
1612 
1613             String local = impl.getLocalHostName();
1614 
1615             if (security != null) {
1616                 security.checkConnect(local, -1);
1617             }
1618 
1619             InetAddress localAddr;
1620             if (local.equals("localhost")) {
1621                 // shortcut for "localhost" host name
1622                 localAddr = impl.loopbackAddress();
1623             } else {
1624                 // call getAllByName0 without security checks and
1625                 // without using cached data
1626                 try {
1627                     localAddr = getAllByName0(local, null, false, false)[0];
1628                 } catch (UnknownHostException uhe) {
1629                     // Rethrow with a more informative error message.
1630                     UnknownHostException uhe2 =
1631                         new UnknownHostException(local + ": " +
1632                                                  uhe.getMessage());
1633                     uhe2.initCause(uhe);
1634                     throw uhe2;
1635                 }
1636             }
1637             cachedLocalHost = new CachedLocalHost(local, localAddr);
1638             return localAddr;
1639         } catch (java.lang.SecurityException e) {
1640             return impl.loopbackAddress();
1641         }
1642     }
1643 
1644     /**
1645      * Perform class load-time initializations.
1646      */
1647     private static native void init();
1648 
1649 
1650     /*
1651      * Returns the InetAddress representing anyLocalAddress
1652      * (typically 0.0.0.0 or ::0)
1653      */
1654     static InetAddress anyLocalAddress() {
1655         return impl.anyLocalAddress();
1656     }
1657 
1658     /*
1659      * Load and instantiate an underlying impl class
1660      */
1661     static InetAddressImpl loadImpl(String implName) {
1662         Object impl = null;
1663 
1664         /*
1665          * Property "impl.prefix" will be prepended to the classname
1666          * of the implementation object we instantiate, to which we
1667          * delegate the real work (like native methods).  This
1668          * property can vary across implementations of the java.
1669          * classes.  The default is an empty String "".
1670          */
1671         String prefix = GetPropertyAction.privilegedGetProperty("impl.prefix", "");
1672         try {
1673             @SuppressWarnings("deprecation")
1674             Object tmp = Class.forName("java.net." + prefix + implName).newInstance();
1675             impl = tmp;
1676         } catch (ClassNotFoundException e) {
1677             System.err.println("Class not found: java.net." + prefix +
1678                                implName + ":\ncheck impl.prefix property " +
1679                                "in your properties file.");
1680         } catch (InstantiationException e) {
1681             System.err.println("Could not instantiate: java.net." + prefix +
1682                                implName + ":\ncheck impl.prefix property " +
1683                                "in your properties file.");
1684         } catch (IllegalAccessException e) {
1685             System.err.println("Cannot access class: java.net." + prefix +
1686                                implName + ":\ncheck impl.prefix property " +
1687                                "in your properties file.");
1688         }
1689 
1690         if (impl == null) {
1691             try {
1692                 @SuppressWarnings("deprecation")
1693                 Object tmp = Class.forName(implName).newInstance();
1694                 impl = tmp;
1695             } catch (Exception e) {
1696                 throw new Error("System property impl.prefix incorrect");
1697             }
1698         }
1699 
1700         return (InetAddressImpl) impl;
1701     }
1702 
1703     private void readObjectNoData (ObjectInputStream s) throws
1704                          IOException, ClassNotFoundException {
1705         if (getClass().getClassLoader() != null) {
1706             throw new SecurityException ("invalid address type");
1707         }
1708     }
1709 
1710     private static final long FIELDS_OFFSET;
1711     private static final jdk.internal.misc.Unsafe UNSAFE;
1712 
1713     static {
1714         try {
1715             jdk.internal.misc.Unsafe unsafe = jdk.internal.misc.Unsafe.getUnsafe();
1716             FIELDS_OFFSET = unsafe.objectFieldOffset(
1717                 InetAddress.class.getDeclaredField("holder")
1718             );
1719             UNSAFE = unsafe;
1720         } catch (ReflectiveOperationException e) {
1721             throw new Error(e);
1722         }
1723     }
1724 
1725     private void readObject (ObjectInputStream s) throws
1726                          IOException, ClassNotFoundException {
1727         if (getClass().getClassLoader() != null) {
1728             throw new SecurityException ("invalid address type");
1729         }
1730         GetField gf = s.readFields();
1731         String host = (String)gf.get("hostName", null);
1732         int address= gf.get("address", 0);
1733         int family= gf.get("family", 0);
1734         InetAddressHolder h = new InetAddressHolder(host, address, family);
1735         UNSAFE.putObject(this, FIELDS_OFFSET, h);
1736     }
1737 
1738     /* needed because the serializable fields no longer exist */
1739 
1740     /**
1741      * @serialField hostName String
1742      * @serialField address int
1743      * @serialField family int
1744      */
1745     private static final ObjectStreamField[] serialPersistentFields = {
1746         new ObjectStreamField("hostName", String.class),
1747         new ObjectStreamField("address", int.class),
1748         new ObjectStreamField("family", int.class),
1749     };
1750 
1751     private void writeObject (ObjectOutputStream s) throws
1752                         IOException {
1753         if (getClass().getClassLoader() != null) {
1754             throw new SecurityException ("invalid address type");
1755         }
1756         PutField pf = s.putFields();
1757         pf.put("hostName", holder().getHostName());
1758         pf.put("address", holder().getAddress());
1759         pf.put("family", holder().getFamily());
1760         s.writeFields();
1761     }
1762 }
1763 
1764 /*
1765  * Simple factory to create the impl
1766  */
1767 class InetAddressImplFactory {
1768 
1769     static InetAddressImpl create() {
1770         return InetAddress.loadImpl(isIPv6Supported() ?
1771                                     "Inet6AddressImpl" : "Inet4AddressImpl");
1772     }
1773 
1774     static native boolean isIPv6Supported();
1775 }