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src/java.base/share/classes/java/net/InetAddress.java

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   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.List;
  29 import java.util.NavigableSet;
  30 import java.util.ArrayList;
  31 import java.util.Objects;
  32 import java.util.Scanner;
  33 import java.io.File;
  34 import java.io.ObjectStreamException;
  35 import java.io.ObjectStreamField;
  36 import java.io.IOException;
  37 import java.io.InvalidObjectException;
  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 import java.util.Arrays;




  48 
  49 import jdk.internal.access.JavaNetInetAddressAccess;
  50 import jdk.internal.access.SharedSecrets;

  51 import sun.security.action.*;
  52 import sun.net.InetAddressCachePolicy;
  53 import sun.net.util.IPAddressUtil;
  54 import sun.nio.cs.UTF_8;
  55 





  56 /**
  57  * This class represents an Internet Protocol (IP) address.
  58  *
  59  * <p> An IP address is either a 32-bit or 128-bit unsigned number
  60  * used by IP, a lower-level protocol on which protocols like UDP and
  61  * TCP are built. The IP address architecture is defined by <a
  62  * href="http://www.ietf.org/rfc/rfc790.txt"><i>RFC&nbsp;790:
  63  * Assigned Numbers</i></a>, <a
  64  * href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC&nbsp;1918:
  65  * Address Allocation for Private Internets</i></a>, <a
  66  * href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC&nbsp;2365:
  67  * Administratively Scoped IP Multicast</i></a>, and <a
  68  * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC&nbsp;2373: IP
  69  * Version 6 Addressing Architecture</i></a>. An instance of an
  70  * InetAddress consists of an IP address and possibly its
  71  * corresponding host name (depending on whether it is constructed
  72  * with a host name or whether it has already done reverse host name
  73  * resolution).
  74  *
  75  * <h2> Address types </h2>

 171  * <dl style="margin-left:2em">
 172  * <dt><b>networkaddress.cache.ttl</b></dt>
 173  * <dd>Indicates the caching policy for successful name lookups from
 174  * the name service. The value is specified as an integer to indicate
 175  * the number of seconds to cache the successful lookup. The default
 176  * setting is to cache for an implementation specific period of time.
 177  * <p>
 178  * A value of -1 indicates "cache forever".
 179  * </dd>
 180  * <dt><b>networkaddress.cache.negative.ttl</b> (default: 10)</dt>
 181  * <dd>Indicates the caching policy for un-successful name lookups
 182  * from the name service. The value is specified as an integer to
 183  * indicate the number of seconds to cache the failure for
 184  * un-successful lookups.
 185  * <p>
 186  * A value of 0 indicates "never cache".
 187  * A value of -1 indicates "cache forever".
 188  * </dd>
 189  * </dl>
 190  *







































 191  * @author  Chris Warth
 192  * @see     java.net.InetAddress#getByAddress(byte[])
 193  * @see     java.net.InetAddress#getByAddress(java.lang.String, byte[])
 194  * @see     java.net.InetAddress#getAllByName(java.lang.String)
 195  * @see     java.net.InetAddress#getByName(java.lang.String)
 196  * @see     java.net.InetAddress#getLocalHost()
 197  * @since 1.0
 198  */
 199 public class InetAddress implements java.io.Serializable {
 200 
 201     @Native static final int PREFER_IPV4_VALUE = 0;
 202     @Native static final int PREFER_IPV6_VALUE = 1;
 203     @Native static final int PREFER_SYSTEM_VALUE = 2;
 204 
 205     /**
 206      * Specify the address family: Internet Protocol, Version 4
 207      * @since 1.4
 208      */
 209     @Native static final int IPv4 = 1;
 210 
 211     /**
 212      * Specify the address family: Internet Protocol, Version 6
 213      * @since 1.4
 214      */
 215     @Native static final int IPv6 = 2;
 216 
 217     /* Specify address family preference */
 218     static transient final int preferIPv6Address;
 219 
 220     static class InetAddressHolder {
 221         /**
 222          * Reserve the original application specified hostname.
 223          *
 224          * The original hostname is useful for domain-based endpoint
 225          * identification (see RFC 2818 and RFC 6125).  If an address
 226          * was created with a raw IP address, a reverse name lookup
 227          * may introduce endpoint identification security issue via
 228          * DNS forging.
 229          *
 230          * Oracle JSSE provider is using this original hostname, via
 231          * jdk.internal.misc.JavaNetAccess, for SSL/TLS endpoint identification.
 232          *
 233          * Note: May define a new public method in the future if necessary.
 234          */
 235         String originalHostName;
 236 
 237         InetAddressHolder() {}
 238 
 239         InetAddressHolder(String hostName, int address, int family) {

 271         }
 272 
 273         /**
 274          * Specifies the address family type, for instance, '1' for IPv4
 275          * addresses, and '2' for IPv6 addresses.
 276          */
 277         int family;
 278 
 279         int getFamily() {
 280             return family;
 281         }
 282     }
 283 
 284     /* Used to store the serializable fields of InetAddress */
 285     final transient InetAddressHolder holder;
 286 
 287     InetAddressHolder holder() {
 288         return holder;
 289     }
 290 
 291     /* Used to store the name service provider */
 292     private static transient NameService nameService;


 293 
 294     /**
 295      * Used to store the best available hostname.
 296      * Lazily initialized via a data race; safe because Strings are immutable.
 297      */
 298     private transient String canonicalHostName = null;
 299 
 300     /** use serialVersionUID from JDK 1.0.2 for interoperability */
 301     @java.io.Serial
 302     private static final long serialVersionUID = 3286316764910316507L;
 303 









 304     /*
 305      * Load net library into runtime, and perform initializations.
 306      */
 307     static {
 308         String str = GetPropertyAction.privilegedGetProperty("java.net.preferIPv6Addresses");
 309         if (str == null) {
 310             preferIPv6Address = PREFER_IPV4_VALUE;
 311         } else if (str.equalsIgnoreCase("true")) {
 312             preferIPv6Address = PREFER_IPV6_VALUE;
 313         } else if (str.equalsIgnoreCase("false")) {
 314             preferIPv6Address = PREFER_IPV4_VALUE;
 315         } else if (str.equalsIgnoreCase("system")) {
 316             preferIPv6Address = PREFER_SYSTEM_VALUE;
 317         } else {
 318             preferIPv6Address = PREFER_IPV4_VALUE;
 319         }
 320         jdk.internal.loader.BootLoader.loadLibrary("net");
 321         SharedSecrets.setJavaNetInetAddressAccess(
 322                 new JavaNetInetAddressAccess() {
 323                     public String getOriginalHostName(InetAddress ia) {
 324                         return ia.holder.getOriginalHostName();
 325                     }
 326 
 327                     public InetAddress getByName(String hostName,
 328                                                  InetAddress hostAddress)
 329                         throws UnknownHostException
 330                     {
 331                         return InetAddress.getByName(hostName, hostAddress);
 332                     }
 333 
 334                     public int addressValue(Inet4Address inet4Address) {
 335                         return inet4Address.addressValue();
 336                     }
 337 
 338                     public byte[] addressBytes(Inet6Address inet6Address) {
 339                         return inet6Address.addressBytes();
 340                     }
 341                 }
 342         );
 343         init();
 344     }
 345 























































































































 346     /**
 347      * Constructor for the Socket.accept() method.
 348      * This creates an empty InetAddress, which is filled in by
 349      * the accept() method.  This InetAddress, however, is not
 350      * put in the address cache, since it is not created by name.
 351      */
 352     InetAddress() {
 353         holder = new InetAddressHolder();
 354     }
 355 
 356     /**
 357      * Replaces the de-serialized object with an Inet4Address object.
 358      *
 359      * @return the alternate object to the de-serialized object.
 360      *
 361      * @throws ObjectStreamException if a new object replacing this
 362      * object could not be created
 363      */
 364     @java.io.Serial
 365     private Object readResolve() throws ObjectStreamException {

 538      * @throws IOException if a network error occurs
 539      * @since 1.5
 540      */
 541     public boolean isReachable(NetworkInterface netif, int ttl,
 542                                int timeout) throws IOException {
 543         if (ttl < 0)
 544             throw new IllegalArgumentException("ttl can't be negative");
 545         if (timeout < 0)
 546             throw new IllegalArgumentException("timeout can't be negative");
 547 
 548         return impl.isReachable(this, timeout, netif, ttl);
 549     }
 550 
 551     /**
 552      * Gets the host name for this IP address.
 553      *
 554      * <p>If this InetAddress was created with a host name,
 555      * this host name will be remembered and returned;
 556      * otherwise, a reverse name lookup will be performed
 557      * and the result will be returned based on the system
 558      * configured name lookup service. If a lookup of the name service
 559      * is required, call
 560      * {@link #getCanonicalHostName() getCanonicalHostName}.
 561      *
 562      * <p>If there is a security manager, its
 563      * {@code checkConnect} method is first called
 564      * with the hostname and {@code -1}
 565      * as its arguments to see if the operation is allowed.
 566      * If the operation is not allowed, it will return
 567      * the textual representation of the IP address.
 568      *
 569      * @return  the host name for this IP address, or if the operation
 570      *    is not allowed by the security check, the textual
 571      *    representation of the IP address.
 572      *
 573      * @see InetAddress#getCanonicalHostName
 574      * @see SecurityManager#checkConnect
 575      */
 576     public String getHostName() {
 577         return getHostName(true);
 578     }

 639     /**
 640      * Returns the hostname for this address.
 641      *
 642      * <p>If there is a security manager, this method first
 643      * calls its {@code checkConnect} method
 644      * with the hostname and {@code -1}
 645      * as its arguments to see if the calling code is allowed to know
 646      * the hostname for this IP address, i.e., to connect to the host.
 647      * If the operation is not allowed, it will return
 648      * the textual representation of the IP address.
 649      *
 650      * @return  the host name for this IP address, or if the operation
 651      *    is not allowed by the security check, the textual
 652      *    representation of the IP address.
 653      *
 654      * @param check make security check if true
 655      *
 656      * @see SecurityManager#checkConnect
 657      */
 658     private static String getHostFromNameService(InetAddress addr, boolean check) {
 659         String host = null;

 660         try {
 661             // first lookup the hostname
 662             host = nameService.getHostByAddr(addr.getAddress());
 663 
 664             /* check to see if calling code is allowed to know
 665              * the hostname for this IP address, ie, connect to the host
 666              */
 667             if (check) {
 668                 @SuppressWarnings("removal")
 669                 SecurityManager sec = System.getSecurityManager();
 670                 if (sec != null) {
 671                     sec.checkConnect(host, -1);
 672                 }
 673             }
 674 
 675             /* now get all the IP addresses for this hostname,
 676              * and make sure one of them matches the original IP
 677              * address. We do this to try and prevent spoofing.
 678              */
 679 
 680             InetAddress[] arr = InetAddress.getAllByName0(host, check);
 681             boolean ok = false;
 682 
 683             if (arr != null) {
 684                 for (int i = 0; !ok && i < arr.length; i++) {
 685                     ok = addr.equals(arr[i]);
 686                 }
 687             }
 688 
 689             //XXX: if it looks like a spoof just return the address?
 690             if (!ok) {
 691                 host = addr.getHostAddress();
 692                 return host;
 693             }
 694         } catch (SecurityException e) {
 695             host = addr.getHostAddress();
 696         } catch (UnknownHostException e) {
 697             host = addr.getHostAddress();
 698             // let next provider resolve the hostname
 699         }
 700         return host;
 701     }
 702 
 703     /**
 704      * Returns the raw IP address of this {@code InetAddress}
 705      * object. The result is in network byte order: the highest order
 706      * byte of the address is in {@code getAddress()[0]}.
 707      *
 708      * @return  the raw IP address of this object.
 709      */
 710     public byte[] getAddress() {
 711         return null;
 712     }
 713 
 714     /**
 715      * Returns the IP address string in textual presentation.
 716      *
 717      * @return  the raw IP address in a string format.
 718      * @since   1.0.2

 738      * <p>
 739      * Two instances of {@code InetAddress} represent the same IP
 740      * address if the length of the byte arrays returned by
 741      * {@code getAddress} is the same for both, and each of the
 742      * array components is the same for the byte arrays.
 743      *
 744      * @param   obj   the object to compare against.
 745      * @return  {@code true} if the objects are the same;
 746      *          {@code false} otherwise.
 747      * @see     java.net.InetAddress#getAddress()
 748      */
 749     public boolean equals(Object obj) {
 750         return false;
 751     }
 752 
 753     /**
 754      * Converts this IP address to a {@code String}. The
 755      * string returned is of the form: hostname / literal IP
 756      * address.
 757      *
 758      * If the host name is unresolved, no reverse name service lookup
 759      * is performed. The hostname part will be represented by an empty string.

 760      *
 761      * @return  a string representation of this IP address.
 762      */
 763     public String toString() {
 764         String hostName = holder().getHostName();
 765         return Objects.toString(hostName, "")
 766             + "/" + getHostAddress();
 767     }
 768 
 769     // mapping from host name to Addresses - either NameServiceAddresses (while
 770     // still being looked-up by NameService(s)) or CachedAddresses when cached
 771     private static final ConcurrentMap<String, Addresses> cache =
 772         new ConcurrentHashMap<>();
 773 
 774     // CachedAddresses that have to expire are kept ordered in this NavigableSet
 775     // which is scanned on each access
 776     private static final NavigableSet<CachedAddresses> expirySet =
 777         new ConcurrentSkipListSet<>();
 778 
 779     // common interface

 804         }
 805 
 806         @Override
 807         public int compareTo(CachedAddresses other) {
 808             // natural order is expiry time -
 809             // compare difference of expiry times rather than
 810             // expiry times directly, to avoid possible overflow.
 811             // (see System.nanoTime() recommendations...)
 812             long diff = this.expiryTime - other.expiryTime;
 813             if (diff < 0L) return -1;
 814             if (diff > 0L) return 1;
 815             // ties are broken using unique id
 816             return Long.compare(this.id, other.id);
 817         }
 818     }
 819 
 820     // a name service lookup based Addresses implementation which replaces itself
 821     // in cache when the result is obtained
 822     private static final class NameServiceAddresses implements Addresses {
 823         private final String host;
 824         private final InetAddress reqAddr;
 825 
 826         NameServiceAddresses(String host, InetAddress reqAddr) {
 827             this.host = host;
 828             this.reqAddr = reqAddr;
 829         }
 830 
 831         @Override
 832         public InetAddress[] get() throws UnknownHostException {
 833             Addresses addresses;
 834             // only one thread is doing lookup to name service
 835             // for particular host at any time.
 836             synchronized (this) {
 837                 // re-check that we are still us + re-install us if slot empty
 838                 addresses = cache.putIfAbsent(host, this);
 839                 if (addresses == null) {
 840                     // this can happen when we were replaced by CachedAddresses in
 841                     // some other thread, then CachedAddresses expired and were
 842                     // removed from cache while we were waiting for lock...
 843                     addresses = this;
 844                 }
 845                 // still us ?
 846                 if (addresses == this) {
 847                     // lookup name services
 848                     InetAddress[] inetAddresses;
 849                     UnknownHostException ex;
 850                     int cachePolicy;
 851                     try {
 852                         inetAddresses = getAddressesFromNameService(host, reqAddr);
 853                         ex = null;
 854                         cachePolicy = InetAddressCachePolicy.get();
 855                     } catch (UnknownHostException uhe) {
 856                         inetAddresses = null;
 857                         ex = uhe;
 858                         cachePolicy = InetAddressCachePolicy.getNegative();
 859                     }
 860                     // remove or replace us with cached addresses according to cachePolicy
 861                     if (cachePolicy == InetAddressCachePolicy.NEVER) {
 862                         cache.remove(host, this);
 863                     } else {
 864                         CachedAddresses cachedAddresses = new CachedAddresses(
 865                             host,
 866                             inetAddresses,
 867                             cachePolicy == InetAddressCachePolicy.FOREVER
 868                             ? 0L
 869                             // cachePolicy is in [s] - we need [ns]
 870                             : System.nanoTime() + 1000_000_000L * cachePolicy
 871                         );
 872                         if (cache.replace(host, this, cachedAddresses) &&
 873                             cachePolicy != InetAddressCachePolicy.FOREVER) {
 874                             // schedule expiry
 875                             expirySet.add(cachedAddresses);
 876                         }
 877                     }
 878                     if (inetAddresses == null) {
 879                         throw ex == null ? new UnknownHostException(host) : ex;
 880                     }
 881                     return inetAddresses;
 882                 }
 883                 // else addresses != this
 884             }
 885             // delegate to different addresses when we are already replaced
 886             // but outside of synchronized block to avoid any chance of dead-locking
 887             return addresses.get();
 888         }
 889     }
 890 
 891     /**
 892      * NameService provides host and address lookup service
 893      *
 894      * @since 9
 895      */
 896     private interface NameService {
 897 
 898         /**
 899          * Lookup a host mapping by name. Retrieve the IP addresses
 900          * associated with a host
 901          *
 902          * @param host the specified hostname
 903          * @return array of IP addresses for the requested host
 904          * @throws UnknownHostException
 905          *             if no IP address for the {@code host} could be found
 906          */
 907         InetAddress[] lookupAllHostAddr(String host)
 908                 throws UnknownHostException;
 909 
 910         /**
 911          * Lookup the host corresponding to the IP address provided
 912          *
 913          * @param addr byte array representing an IP address
 914          * @return {@code String} representing the host name mapping
 915          * @throws UnknownHostException
 916          *             if no host found for the specified IP address
 917          */
 918         String getHostByAddr(byte[] addr) throws UnknownHostException;
 919 
 920     }
 921 
 922     /**
 923      * The default NameService implementation, which delegates to the underlying
 924      * OS network libraries to resolve host address mappings.
 925      *
 926      * @since 9
 927      */
 928     private static final class PlatformNameService implements NameService {
 929 
 930         public InetAddress[] lookupAllHostAddr(String host)
 931             throws UnknownHostException
 932         {
 933             return impl.lookupAllHostAddr(host);
 934         }
 935 
 936         public String getHostByAddr(byte[] addr)
 937             throws UnknownHostException
 938         {


 939             return impl.getHostByAddr(addr);
 940         }
 941     }
 942 
 943     /**
 944      * The HostsFileNameService provides host address mapping
 945      * by reading the entries in a hosts file, which is specified by
 946      * {@code jdk.net.hosts.file} system property
 947      *
 948      * <p>The file format is that which corresponds with the /etc/hosts file
 949      * IP Address host alias list.
 950      *
 951      * <p>When the file lookup is enabled it replaces the default NameService
 952      * implementation
 953      *
 954      * @since 9
 955      */
 956     private static final class HostsFileNameService implements NameService {
 957 
 958         private static final InetAddress[] EMPTY_ARRAY = new InetAddress[0];
 959 
 960         // Specify if only IPv4 addresses should be returned by HostsFileService implementation
 961         private static final boolean preferIPv4Stack = Boolean.parseBoolean(
 962                 GetPropertyAction.privilegedGetProperty("java.net.preferIPv4Stack"));
 963 
 964         private final String hostsFile;
 965 
 966         public HostsFileNameService(String hostsFileName) {
 967             this.hostsFile = hostsFileName;
 968         }
 969 
 970         /**
 971          * Lookup the host name  corresponding to the IP address provided.
 972          * Search the configured host file a host name corresponding to
 973          * the specified IP address.
 974          *
 975          * @param addr byte array representing an IP address
 976          * @return {@code String} representing the host name mapping
 977          * @throws UnknownHostException
 978          *             if no host found for the specified IP address
 979          */
 980         @Override
 981         public String getHostByAddr(byte[] addr) throws UnknownHostException {
 982             String hostEntry;
 983             String host = null;
 984 





 985             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
 986                                                         UTF_8.INSTANCE))
 987             {
 988                 while (hostsFileScanner.hasNextLine()) {
 989                     hostEntry = hostsFileScanner.nextLine();
 990                     if (!hostEntry.startsWith("#")) {
 991                         hostEntry = removeComments(hostEntry);
 992                         String[] mapping = hostEntry.split("\\s+");
 993                         if (mapping.length >= 2 &&
 994                             Arrays.equals(addr, createAddressByteArray(mapping[0]))) {
 995                             host = mapping[1];
 996                             break;
 997                         }
 998                     }
 999                 }
1000             } catch (IOException e) {
1001                 throw new UnknownHostException("Unable to resolve address "
1002                         + Arrays.toString(addr) + " as hosts file " + hostsFile
1003                         + " not found ");
1004             }
1005 
1006             if ((host == null) || (host.isEmpty()) || (host.equals(" "))) {
1007                 throw new UnknownHostException("Requested address "
1008                         + Arrays.toString(addr)
1009                         + " resolves to an invalid entry in hosts file "
1010                         + hostsFile);
1011             }
1012             return host;
1013         }
1014 
1015         /**
1016          * <p>Lookup a host mapping by name. Retrieve the IP addresses
1017          * associated with a host.
1018          *
1019          * <p>Search the configured hosts file for the addresses associated
1020          * with the specified host name.
1021          *
1022          * @param host the specified hostname
1023          * @return array of IP addresses for the requested host


1024          * @throws UnknownHostException
1025          *             if no IP address for the {@code host} could be found
1026          */
1027         public InetAddress[] lookupAllHostAddr(String host)
1028                 throws UnknownHostException {
1029             String hostEntry;
1030             String addrStr;
1031             byte addr[];
1032             List<InetAddress> inetAddresses = new ArrayList<>();
1033             List<InetAddress> inet4Addresses = new ArrayList<>();
1034             List<InetAddress> inet6Addresses = new ArrayList<>();





1035 
1036             // lookup the file and create a list InetAddress for the specified host
1037             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
1038                                                         UTF_8.INSTANCE)) {
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.isEmpty())) {
1046                                 addr = createAddressByteArray(addrStr);
1047                                 if (addr != null) {
1048                                     InetAddress address = InetAddress.getByAddress(host, addr);
1049                                     inetAddresses.add(address);
1050                                     if (address instanceof Inet4Address) {
1051                                         inet4Addresses.add(address);
1052                                     }
1053                                     if (address instanceof Inet6Address) {
1054                                         inet6Addresses.add(address);
1055                                     }
1056                                 }
1057                             }
1058                         }
1059                     }
1060                 }
1061             } catch (IOException e) {
1062                 throw new UnknownHostException("Unable to resolve host " + host
1063                         + " as hosts file " + hostsFile + " not found ");
1064             }
1065 
1066             List<InetAddress> res;
1067             // If "preferIPv4Stack" system property is set to "true" then return
1068             // only IPv4 addresses
1069             if (preferIPv4Stack) {
1070                 res = inet4Addresses;
1071             } else {
1072                 // Otherwise, analyse "preferIPv6Addresses" value
1073                 res = switch (preferIPv6Address) {
1074                     case PREFER_IPV4_VALUE -> concatAddresses(inet4Addresses, inet6Addresses);
1075                     case PREFER_IPV6_VALUE -> concatAddresses(inet6Addresses, inet4Addresses);
1076                     default -> inetAddresses;
1077                 };
1078             }
1079 
1080             if (res.isEmpty()) {
1081                 throw new UnknownHostException("Unable to resolve host " + host
1082                         + " in hosts file " + hostsFile);
1083             }
1084             return res.toArray(EMPTY_ARRAY);
1085         }
1086 
1087         private static List<InetAddress> concatAddresses(List<InetAddress> firstPart,
1088                                                          List<InetAddress> secondPart) {
1089             List<InetAddress> result = new ArrayList<>(firstPart);
1090             result.addAll(secondPart);
1091             return result;











1092         }
1093 
1094         private String removeComments(String hostsEntry) {
1095             String filteredEntry = hostsEntry;
1096             int hashIndex;
1097 
1098             if ((hashIndex = hostsEntry.indexOf("#")) != -1) {
1099                 filteredEntry = hostsEntry.substring(0, hashIndex);
1100             }
1101             return filteredEntry;
1102         }
1103 
1104         private byte [] createAddressByteArray(String addrStr) {
1105             byte[] addrArray;
1106             // check if IPV4 address - most likely
1107             addrArray = IPAddressUtil.textToNumericFormatV4(addrStr);
1108             if (addrArray == null) {
1109                 addrArray = IPAddressUtil.textToNumericFormatV6(addrStr);
1110             }
1111             return addrArray;

1113 
1114         /** host to ip address mapping */
1115         private String extractHostAddr(String hostEntry, String host) {
1116             String[] mapping = hostEntry.split("\\s+");
1117             String hostAddr = null;
1118 
1119             if (mapping.length >= 2) {
1120                 // look at the host aliases
1121                 for (int i = 1; i < mapping.length; i++) {
1122                     if (mapping[i].equalsIgnoreCase(host)) {
1123                         hostAddr = mapping[0];
1124                     }
1125                 }
1126             }
1127             return hostAddr;
1128         }
1129     }
1130 
1131     static final InetAddressImpl  impl;
1132 






1133     static {
1134         // create the impl
1135         impl = InetAddressImplFactory.create();
1136 
1137         // create name service
1138         nameService = createNameService();



1139     }
1140 
1141     /**
1142      * Create an instance of the NameService interface based on
1143      * the setting of the {@code jdk.net.hosts.file} system property.
1144      *
1145      * <p>The default NameService is the PlatformNameService, which typically
1146      * delegates name and address resolution calls to the underlying
1147      * OS network libraries.
1148      *
1149      * <p> A HostsFileNameService is created if the {@code jdk.net.hosts.file}
1150      * system property is set. If the specified file doesn't exist, the name or
1151      * address lookup will result in an UnknownHostException. Thus, non existent
1152      * hosts file is handled as if the file is empty.
1153      *
1154      * @return a NameService
1155      */
1156     private static NameService createNameService() {
1157 
1158         String hostsFileName =
1159                 GetPropertyAction.privilegedGetProperty("jdk.net.hosts.file");
1160         NameService theNameService;
1161         if (hostsFileName != null) {
1162             theNameService = new HostsFileNameService(hostsFileName);
1163         } else {
1164             theNameService = new PlatformNameService();
1165         }
1166         return theNameService;
1167     }
1168 
1169     /**
1170      * Creates an InetAddress based on the provided host name and IP address.
1171      * No name service is checked for the validity of the address.

1172      *
1173      * <p> The host name can either be a machine name, such as
1174      * "{@code www.example.com}", or a textual representation of its IP
1175      * address.
1176      * <p> No validity checking is done on the host name either.
1177      *
1178      * <p> If addr specifies an IPv4 address an instance of Inet4Address
1179      * will be returned; otherwise, an instance of Inet6Address
1180      * will be returned.
1181      *
1182      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1183      * must be 16 bytes long
1184      *
1185      * @param host the specified host
1186      * @param addr the raw IP address in network byte order
1187      * @return  an InetAddress object created from the raw IP address.
1188      * @throws     UnknownHostException  if IP address is of illegal length
1189      * @since 1.4
1190      */
1191     public static InetAddress getByAddress(String host, byte[] addr)

1234      * section&nbsp;2.5.3.
1235      *
1236      * <p> If there is a security manager, and {@code host} is not {@code null}
1237      * or {@code host.length() } is not equal to zero, the security manager's
1238      * {@code checkConnect} method is called with the hostname and {@code -1}
1239      * as its arguments to determine if the operation is allowed.
1240      *
1241      * @param      host   the specified host, or {@code null}.
1242      * @return     an IP address for the given host name.
1243      * @throws     UnknownHostException  if no IP address for the
1244      *               {@code host} could be found, or if a scope_id was specified
1245      *               for a global IPv6 address.
1246      * @throws     SecurityException if a security manager exists
1247      *             and its checkConnect method doesn't allow the operation
1248      */
1249     public static InetAddress getByName(String host)
1250         throws UnknownHostException {
1251         return InetAddress.getAllByName(host)[0];
1252     }
1253 
1254     // called from deployment cache manager
1255     private static InetAddress getByName(String host, InetAddress reqAddr)
1256         throws UnknownHostException {
1257         return InetAddress.getAllByName(host, reqAddr)[0];
1258     }
1259 
1260     /**
1261      * Given the name of a host, returns an array of its IP addresses,
1262      * based on the configured name service on the system.
1263      *
1264      * <p> The host name can either be a machine name, such as
1265      * "{@code www.example.com}", or a textual representation of its IP
1266      * address. If a literal IP address is supplied, only the
1267      * validity of the address format is checked.
1268      *
1269      * <p> For {@code host} specified in <i>literal IPv6 address</i>,
1270      * either the form defined in RFC 2732 or the literal IPv6 address
1271      * format defined in RFC 2373 is accepted. A literal IPv6 address may
1272      * also be qualified by appending a scoped zone identifier or scope_id.
1273      * The syntax and usage of scope_ids is described
1274      * <a href="Inet6Address.html#scoped">here</a>.
1275      *
1276      * <p> If the host is {@code null} or {@code host.length()} is equal
1277      * to zero, then an {@code InetAddress} representing an address of the
1278      * loopback interface is returned.
1279      * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC&nbsp;3330</a>
1280      * section&nbsp;2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC&nbsp;2373</a>
1281      * section&nbsp;2.5.3. </p>
1282      *
1283      * <p> If there is a security manager, and {@code host} is not {@code null}
1284      * or {@code host.length() } is not equal to zero, the security manager's
1285      * {@code checkConnect} method is called with the hostname and {@code -1}
1286      * as its arguments to determine if the operation is allowed.
1287      *
1288      * @param      host   the name of the host, or {@code null}.
1289      * @return     an array of all the IP addresses for a given host name.
1290      *
1291      * @throws     UnknownHostException  if no IP address for the
1292      *               {@code host} could be found, or if a scope_id was specified
1293      *               for a global IPv6 address.
1294      * @throws     SecurityException  if a security manager exists and its
1295      *               {@code checkConnect} method doesn't allow the operation.
1296      *
1297      * @see SecurityManager#checkConnect
1298      */
1299     public static InetAddress[] getAllByName(String host)
1300         throws UnknownHostException {
1301         return getAllByName(host, null);
1302     }
1303 
1304     private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
1305         throws UnknownHostException {
1306 
1307         if (host == null || host.isEmpty()) {
1308             InetAddress[] ret = new InetAddress[1];
1309             ret[0] = impl.loopbackAddress();
1310             return ret;
1311         }
1312 
1313         boolean ipv6Expected = false;
1314         if (host.charAt(0) == '[') {
1315             // This is supposed to be an IPv6 literal
1316             if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1317                 host = host.substring(1, host.length() -1);
1318                 ipv6Expected = true;
1319             } else {
1320                 // This was supposed to be a IPv6 address, but it's not!
1321                 throw new UnknownHostException(host + ": invalid IPv6 address");
1322             }
1323         }
1324 
1325         // if host is an IP address, we won't do further lookup

1347                 // Means an IPv4 literal between brackets!
1348                 throw new UnknownHostException("["+host+"]");
1349             }
1350             InetAddress[] ret = new InetAddress[1];
1351             if(addr != null) {
1352                 if (addr.length == Inet4Address.INADDRSZ) {
1353                     ret[0] = new Inet4Address(null, addr);
1354                 } else {
1355                     if (ifname != null) {
1356                         ret[0] = new Inet6Address(null, addr, ifname);
1357                     } else {
1358                         ret[0] = new Inet6Address(null, addr, numericZone);
1359                     }
1360                 }
1361                 return ret;
1362             }
1363         } else if (ipv6Expected) {
1364             // We were expecting an IPv6 Literal, but got something else
1365             throw new UnknownHostException("["+host+"]");
1366         }
1367         return getAllByName0(host, reqAddr, true, true);
1368     }
1369 
1370     /**
1371      * Returns the loopback address.
1372      * <p>
1373      * The InetAddress returned will represent the IPv4
1374      * loopback address, 127.0.0.1, or the IPv6 loopback
1375      * address, ::1. The IPv4 loopback address returned
1376      * is only one of many in the form 127.*.*.*
1377      *
1378      * @return  the InetAddress loopback instance.
1379      * @since 1.7
1380      */
1381     public static InetAddress getLoopbackAddress() {
1382         return impl.loopbackAddress();
1383     }
1384 
1385 
1386     /**
1387      * check if the literal address string has %nn appended

1397         if (percent == -1) {
1398             return -1;
1399         }
1400         for (int i=percent+1; i<slen; i++) {
1401             char c = s.charAt(i);
1402             if (c == ']') {
1403                 if (i == percent+1) {
1404                     /* empty per-cent field */
1405                     return -1;
1406                 }
1407                 break;
1408             }
1409             if ((digit = Character.digit (c, 10)) < 0) {
1410                 return -1;
1411             }
1412             zone = (zone * 10) + digit;
1413         }
1414         return zone;
1415     }
1416 
1417     private static InetAddress[] getAllByName0 (String host)
1418         throws UnknownHostException
1419     {
1420         return getAllByName0(host, true);
1421     }
1422 
1423     /**
1424      * package private so SocketPermission can call it
1425      */
1426     static InetAddress[] getAllByName0 (String host, boolean check)
1427         throws UnknownHostException  {
1428         return getAllByName0 (host, null, check, true);
1429     }
1430 
1431     /**
1432      * Designated lookup method.
1433      *
1434      * @param host host name to look up
1435      * @param reqAddr requested address to be the 1st in returned array
1436      * @param check perform security check
1437      * @param useCache use cached value if not expired else always
1438      *                 perform name service lookup (and cache the result)
1439      * @return array of InetAddress(es)
1440      * @throws UnknownHostException if host name is not found
1441      */
1442     private static InetAddress[] getAllByName0(String host,
1443                                                InetAddress reqAddr,
1444                                                boolean check,
1445                                                boolean useCache)
1446         throws UnknownHostException  {
1447 
1448         /* If it gets here it is presumed to be a hostname */
1449 
1450         /* make sure the connection to the host is allowed, before we
1451          * give out a hostname
1452          */
1453         if (check) {
1454             @SuppressWarnings("removal")
1455             SecurityManager security = System.getSecurityManager();
1456             if (security != null) {
1457                 security.checkConnect(host, -1);
1458             }
1459         }
1460 
1461         // remove expired addresses from cache - expirySet keeps them ordered
1462         // by expiry time so we only need to iterate the prefix of the NavigableSet...
1463         long now = System.nanoTime();

1481         // look-up or remove from cache
1482         Addresses addrs;
1483         if (useCache) {
1484             addrs = cache.get(host);
1485         } else {
1486             addrs = cache.remove(host);
1487             if (addrs != null) {
1488                 if (addrs instanceof CachedAddresses) {
1489                     // try removing from expirySet too if CachedAddresses
1490                     expirySet.remove(addrs);
1491                 }
1492                 addrs = null;
1493             }
1494         }
1495 
1496         if (addrs == null) {
1497             // create a NameServiceAddresses instance which will look up
1498             // the name service and install it within cache...
1499             Addresses oldAddrs = cache.putIfAbsent(
1500                 host,
1501                 addrs = new NameServiceAddresses(host, reqAddr)
1502             );
1503             if (oldAddrs != null) { // lost putIfAbsent race
1504                 addrs = oldAddrs;
1505             }
1506         }
1507 
1508         // ask Addresses to get an array of InetAddress(es) and clone it
1509         return addrs.get().clone();
1510     }
1511 
1512     static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
1513             throws UnknownHostException {
1514         InetAddress[] addresses = null;
1515         UnknownHostException ex = null;
1516 

1517         try {
1518             addresses = nameService.lookupAllHostAddr(host);
1519         } catch (UnknownHostException uhe) {
1520             if (host.equalsIgnoreCase("localhost")) {
1521                 addresses = new InetAddress[]{impl.loopbackAddress()};
1522             } else {
1523                 ex = uhe;



1524             }
1525         }
1526 
1527         if (addresses == null) {
1528             throw ex == null ? new UnknownHostException(host) : ex;
1529         }
1530 
1531         // More to do?
1532         if (reqAddr != null && addresses.length > 1 && !addresses[0].equals(reqAddr)) {
1533             // Find it?
1534             int i = 1;
1535             for (; i < addresses.length; i++) {
1536                 if (addresses[i].equals(reqAddr)) {
1537                     break;
1538                 }
1539             }
1540             // Rotate
1541             if (i < addresses.length) {
1542                 InetAddress tmp, tmp2 = reqAddr;
1543                 for (int j = 0; j < i; j++) {
1544                     tmp = addresses[j];
1545                     addresses[j] = tmp2;
1546                     tmp2 = tmp;
1547                 }
1548                 addresses[i] = tmp2;
1549             }
1550         }
1551 
1552         return addresses;
1553     }
1554 
1555     /**
1556      * Returns an {@code InetAddress} object given the raw IP address .
1557      * The argument is in network byte order: the highest order
1558      * byte of the address is in {@code getAddress()[0]}.
1559      *
1560      * <p> This method doesn't block, i.e. no reverse name service lookup
1561      * is performed.
1562      *
1563      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1564      * must be 16 bytes long
1565      *
1566      * @param addr the raw IP address in network byte order
1567      * @return  an InetAddress object created from the raw IP address.
1568      * @throws     UnknownHostException  if IP address is of illegal length
1569      * @since 1.4
1570      */
1571     public static InetAddress getByAddress(byte[] addr)
1572         throws UnknownHostException {
1573         return getByAddress(null, addr);
1574     }
1575 
1576     private static final class CachedLocalHost {
1577         final String host;
1578         final InetAddress addr;
1579         final long expiryTime = System.nanoTime() + 5000_000_000L; // now + 5s;
1580 
1581         CachedLocalHost(String host, InetAddress addr) {

1620                 if (security != null) {
1621                     security.checkConnect(clh.host, -1);
1622                 }
1623                 return clh.addr;
1624             }
1625 
1626             String local = impl.getLocalHostName();
1627 
1628             if (security != null) {
1629                 security.checkConnect(local, -1);
1630             }
1631 
1632             InetAddress localAddr;
1633             if (local.equals("localhost")) {
1634                 // shortcut for "localhost" host name
1635                 localAddr = impl.loopbackAddress();
1636             } else {
1637                 // call getAllByName0 without security checks and
1638                 // without using cached data
1639                 try {
1640                     localAddr = getAllByName0(local, null, false, false)[0];
1641                 } catch (UnknownHostException uhe) {
1642                     // Rethrow with a more informative error message.
1643                     UnknownHostException uhe2 =
1644                         new UnknownHostException(local + ": " +
1645                                                  uhe.getMessage());
1646                     uhe2.initCause(uhe);
1647                     throw uhe2;
1648                 }
1649             }
1650             cachedLocalHost = new CachedLocalHost(local, localAddr);
1651             return localAddr;
1652         } catch (java.lang.SecurityException e) {
1653             return impl.loopbackAddress();
1654         }
1655     }
1656 
1657     /**
1658      * Perform class load-time initializations.
1659      */
1660     private static native void init();

   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 sun.net.ResolverProviderConfiguration;
  62 import sun.security.action.*;
  63 import sun.net.InetAddressCachePolicy;
  64 import sun.net.util.IPAddressUtil;
  65 import sun.nio.cs.UTF_8;
  66 
  67 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV4;
  68 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV4_FIRST;
  69 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV6;
  70 import static java.net.spi.InetAddressResolver.LookupPolicy.IPV6_FIRST;
  71 
  72 /**
  73  * This class represents an Internet Protocol (IP) address.
  74  *
  75  * <p> An IP address is either a 32-bit or 128-bit unsigned number
  76  * used by IP, a lower-level protocol on which protocols like UDP and
  77  * TCP are built. The IP address architecture is defined by <a
  78  * href="http://www.ietf.org/rfc/rfc790.txt"><i>RFC&nbsp;790:
  79  * Assigned Numbers</i></a>, <a
  80  * href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC&nbsp;1918:
  81  * Address Allocation for Private Internets</i></a>, <a
  82  * href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC&nbsp;2365:
  83  * Administratively Scoped IP Multicast</i></a>, and <a
  84  * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC&nbsp;2373: IP
  85  * Version 6 Addressing Architecture</i></a>. An instance of an
  86  * InetAddress consists of an IP address and possibly its
  87  * corresponding host name (depending on whether it is constructed
  88  * with a host name or whether it has already done reverse host name
  89  * resolution).
  90  *
  91  * <h2> Address types </h2>

 187  * <dl style="margin-left:2em">
 188  * <dt><b>networkaddress.cache.ttl</b></dt>
 189  * <dd>Indicates the caching policy for successful name lookups from
 190  * the name service. The value is specified as an integer to indicate
 191  * the number of seconds to cache the successful lookup. The default
 192  * setting is to cache for an implementation specific period of time.
 193  * <p>
 194  * A value of -1 indicates "cache forever".
 195  * </dd>
 196  * <dt><b>networkaddress.cache.negative.ttl</b> (default: 10)</dt>
 197  * <dd>Indicates the caching policy for un-successful name lookups
 198  * from the name service. The value is specified as an integer to
 199  * indicate the number of seconds to cache the failure for
 200  * un-successful lookups.
 201  * <p>
 202  * A value of 0 indicates "never cache".
 203  * A value of -1 indicates "cache forever".
 204  * </dd>
 205  * </dl>
 206  *
 207  * <h3 id="resolverProviders"> InetAddress Resolver Providers </h3>
 208  *
 209  * <p> Host name resolution and reverse name resolution operations are delegated to a
 210  * {@linkplain InetAddressResolver resolver}. Lookup operations performed by
 211  * this class use the <i>system-wide resolver</i>. The system-wide resolver
 212  * is set once, lazily, after the VM is fully initialized and when
 213  * an invocation of a method in this class triggers the first lookup operation.
 214  *
 215  * <p> A <i>custom resolver</i> can be installed as the system-wide resolver
 216  * by deploying a {@linkplain InetAddressResolverProvider resolver provider}.
 217  * A resolver provider is essentially a factory for resolvers, and is used
 218  * to instantiate a custom resolver. If no resolver provider
 219  * is found, then the <i>built-in resolver</i> will be set as the
 220  * system-wide resolver.
 221  *
 222  * <p> A custom resolver is found and installed as the system-wide resolver
 223  * as follows:
 224  * <ol>
 225  *  <li>The {@link ServiceLoader} mechanism is used to locate an
 226  *      {@link InetAddressResolverProvider InetAddressResolverProvider} using the
 227  *      system class loader. The order in which providers are located is
 228  *      {@linkplain ServiceLoader#load(java.lang.Class, java.lang.ClassLoader) implementation specific}.
 229  *      The first provider found will be used to instantiate the {@link InetAddressResolver InetAddressResolver}
 230  *      by invoking the {@link InetAddressResolverProvider#get(InetAddressResolverProvider.Configuration)}
 231  *      method. The instantiated {@code InetAddressResolver} will be installed as the system-wide
 232  *      resolver.
 233  *  <li>If the previous step fails to find any resolver provider the
 234  *      built-in resolver will be set as the system-wide resolver.
 235  * </ol>
 236  *
 237  * <p> If instantiating a custom resolver from a provider discovered in
 238  * step 1 throws an error or exception, the system-wide resolver will not be
 239  * installed and the error or exception will be propagated to the calling thread.
 240  * Otherwise, any lookup operation will be performed through the installed
 241  * <i>system-wide resolver</i>.
 242  * @implNote
 243  * For any lookup operation that might occur before the VM is fully booted the <i>built-in
 244  * resolver</i> will be used.
 245  *
 246  * @author  Chris Warth
 247  * @see     java.net.InetAddress#getByAddress(byte[])
 248  * @see     java.net.InetAddress#getByAddress(java.lang.String, byte[])
 249  * @see     java.net.InetAddress#getAllByName(java.lang.String)
 250  * @see     java.net.InetAddress#getByName(java.lang.String)
 251  * @see     java.net.InetAddress#getLocalHost()
 252  * @since 1.0
 253  */
 254 public class InetAddress implements java.io.Serializable {
 255 




 256     /**
 257      * Specify the address family: Internet Protocol, Version 4
 258      * @since 1.4
 259      */
 260     @Native static final int IPv4 = 1;
 261 
 262     /**
 263      * Specify the address family: Internet Protocol, Version 6
 264      * @since 1.4
 265      */
 266     @Native static final int IPv6 = 2;
 267 



 268     static class InetAddressHolder {
 269         /**
 270          * Reserve the original application specified hostname.
 271          *
 272          * The original hostname is useful for domain-based endpoint
 273          * identification (see RFC 2818 and RFC 6125).  If an address
 274          * was created with a raw IP address, a reverse name lookup
 275          * may introduce endpoint identification security issue via
 276          * DNS forging.
 277          *
 278          * Oracle JSSE provider is using this original hostname, via
 279          * jdk.internal.misc.JavaNetAccess, for SSL/TLS endpoint identification.
 280          *
 281          * Note: May define a new public method in the future if necessary.
 282          */
 283         String originalHostName;
 284 
 285         InetAddressHolder() {}
 286 
 287         InetAddressHolder(String hostName, int address, int family) {

 319         }
 320 
 321         /**
 322          * Specifies the address family type, for instance, '1' for IPv4
 323          * addresses, and '2' for IPv6 addresses.
 324          */
 325         int family;
 326 
 327         int getFamily() {
 328             return family;
 329         }
 330     }
 331 
 332     /* Used to store the serializable fields of InetAddress */
 333     final transient InetAddressHolder holder;
 334 
 335     InetAddressHolder holder() {
 336         return holder;
 337     }
 338 
 339     /* Used to store the system-wide resolver */
 340     private static volatile InetAddressResolver resolver;
 341 
 342     private static final InetAddressResolver BUILTIN_RESOLVER;
 343 
 344     /**
 345      * Used to store the best available hostname.
 346      * Lazily initialized via a data race; safe because Strings are immutable.
 347      */
 348     private transient String canonicalHostName = null;
 349 
 350     /** use serialVersionUID from JDK 1.0.2 for interoperability */
 351     @java.io.Serial
 352     private static final long serialVersionUID = 3286316764910316507L;
 353 
 354     // "java.net.preferIPv4Stack" system property value
 355     private static final String PREFER_IPV4_STACK_VALUE;
 356 
 357     // "java.net.preferIPv6Addresses" system property value
 358     private static final String PREFER_IPV6_ADDRESSES_VALUE;
 359 
 360     // "jdk.net.hosts.file" system property value
 361     private static final String HOSTS_FILE_NAME;
 362 
 363     /*
 364      * Load net library into runtime, and perform initializations.
 365      */
 366     static {
 367         PREFER_IPV4_STACK_VALUE =
 368                 GetPropertyAction.privilegedGetProperty("java.net.preferIPv4Stack");
 369         PREFER_IPV6_ADDRESSES_VALUE =
 370                 GetPropertyAction.privilegedGetProperty("java.net.preferIPv6Addresses");
 371         HOSTS_FILE_NAME =
 372                 GetPropertyAction.privilegedGetProperty("jdk.net.hosts.file");






 373         jdk.internal.loader.BootLoader.loadLibrary("net");
 374         SharedSecrets.setJavaNetInetAddressAccess(
 375                 new JavaNetInetAddressAccess() {
 376                     public String getOriginalHostName(InetAddress ia) {
 377                         return ia.holder.getOriginalHostName();
 378                     }
 379 







 380                     public int addressValue(Inet4Address inet4Address) {
 381                         return inet4Address.addressValue();
 382                     }
 383 
 384                     public byte[] addressBytes(Inet6Address inet6Address) {
 385                         return inet6Address.addressBytes();
 386                     }
 387                 }
 388         );
 389         init();
 390     }
 391 
 392     /**
 393      * Creates an address lookup policy from {@code "java.net.preferIPv4Stack"},
 394      * {@code "java.net.preferIPv6Addresses"} system property values, and O/S configuration.
 395      */
 396     private static final LookupPolicy initializePlatformLookupPolicy() {
 397         // Calculate AddressFamily value first
 398         boolean ipv4Available = isIPv4Available();
 399         if ("true".equals(PREFER_IPV4_STACK_VALUE) && ipv4Available) {
 400             return LookupPolicy.of(IPV4);
 401         }
 402         // Check if IPv6 is not supported
 403         if (InetAddress.impl instanceof Inet4AddressImpl) {
 404             return LookupPolicy.of(IPV4);
 405         }
 406         // Check if system supports IPv4, if not use IPv6
 407         if (!ipv4Available) {
 408             return LookupPolicy.of(IPV6);
 409         }
 410         // If both address families are needed - check preferIPv6Addresses value
 411         if (PREFER_IPV6_ADDRESSES_VALUE != null) {
 412             if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("true")) {
 413                 return LookupPolicy.of(IPV4 | IPV6 | IPV6_FIRST);
 414             }
 415             if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("false")) {
 416                 return LookupPolicy.of(IPV4 | IPV6 | IPV4_FIRST);
 417             }
 418             if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("system")) {
 419                 return LookupPolicy.of(IPV4 | IPV6);
 420             }
 421         }
 422         // Default value with both address families needed - IPv4 addresses come first
 423         return LookupPolicy.of(IPV4 | IPV6 | IPV4_FIRST);
 424     }
 425 
 426     static boolean systemAddressesOrder(int lookupCharacteristics) {
 427         return (lookupCharacteristics & (IPV4_FIRST | IPV6_FIRST)) == 0;
 428     }
 429 
 430     static boolean ipv4AddressesFirst(int lookupCharacteristics) {
 431         return (lookupCharacteristics & IPV4_FIRST) != 0;
 432     }
 433 
 434     static boolean ipv6AddressesFirst(int lookupCharacteristics) {
 435         return (lookupCharacteristics & IPV6_FIRST) != 0;
 436     }
 437 
 438     // Native method to check if IPv4 is available
 439     private static native boolean isIPv4Available();
 440 
 441     /**
 442      * The {@code RuntimePermission("inetAddressResolverProvider")} is
 443      * necessary to subclass and instantiate the {@code InetAddressResolverProvider}
 444      * class, as well as to obtain resolver from an instance of that class,
 445      * and it is also required to obtain the operating system name resolution configurations.
 446      */
 447     private static final RuntimePermission INET_ADDRESS_RESOLVER_PERMISSION =
 448             new RuntimePermission("inetAddressResolverProvider");
 449 
 450     private static final ReentrantLock RESOLVER_LOCK = new ReentrantLock();
 451     private static volatile InetAddressResolver bootstrapResolver;
 452 
 453     @SuppressWarnings("removal")
 454     private static InetAddressResolver resolver() {
 455         InetAddressResolver cns = resolver;
 456         if (cns != null) {
 457             return cns;
 458         }
 459         if (VM.isBooted()) {
 460             RESOLVER_LOCK.lock();
 461             try {
 462                 cns = resolver;
 463                 if (cns != null) {
 464                     return cns;
 465                 }
 466                 // Protection against provider calling InetAddress APIs during initialization
 467                 if (bootstrapResolver != null) {
 468                     return bootstrapResolver;
 469                 } else {
 470                     bootstrapResolver = BUILTIN_RESOLVER;
 471                 }
 472                 if (HOSTS_FILE_NAME != null) {
 473                     // The default resolver service is already host file resolver
 474                     cns = BUILTIN_RESOLVER;
 475                 } else if (System.getSecurityManager() != null) {
 476                     PrivilegedAction<InetAddressResolver> pa = InetAddress::loadResolver;
 477                     cns = AccessController.doPrivileged(
 478                             pa, null, INET_ADDRESS_RESOLVER_PERMISSION);
 479                 } else {
 480                     cns = loadResolver();
 481                 }
 482 
 483                 InetAddress.resolver = cns;
 484                 return cns;
 485             } finally {
 486                 bootstrapResolver = null;
 487                 RESOLVER_LOCK.unlock();
 488             }
 489         } else {
 490             return BUILTIN_RESOLVER;
 491         }
 492     }
 493 
 494     private static InetAddressResolver loadResolver() {
 495         return ServiceLoader.load(InetAddressResolverProvider.class)
 496                 .findFirst()
 497                 .map(nsp -> nsp.get(builtinConfiguration()))
 498                 .orElse(BUILTIN_RESOLVER);
 499     }
 500 
 501     private static InetAddressResolverProvider.Configuration builtinConfiguration() {
 502         return new ResolverProviderConfiguration(BUILTIN_RESOLVER, () -> {
 503             try {
 504                 return impl.getLocalHostName();
 505             } catch (UnknownHostException unknownHostException) {
 506                 return "localhost";
 507             }
 508         });
 509     }
 510 
 511     /**
 512      * Constructor for the Socket.accept() method.
 513      * This creates an empty InetAddress, which is filled in by
 514      * the accept() method.  This InetAddress, however, is not
 515      * put in the address cache, since it is not created by name.
 516      */
 517     InetAddress() {
 518         holder = new InetAddressHolder();
 519     }
 520 
 521     /**
 522      * Replaces the de-serialized object with an Inet4Address object.
 523      *
 524      * @return the alternate object to the de-serialized object.
 525      *
 526      * @throws ObjectStreamException if a new object replacing this
 527      * object could not be created
 528      */
 529     @java.io.Serial
 530     private Object readResolve() throws ObjectStreamException {

 703      * @throws IOException if a network error occurs
 704      * @since 1.5
 705      */
 706     public boolean isReachable(NetworkInterface netif, int ttl,
 707                                int timeout) throws IOException {
 708         if (ttl < 0)
 709             throw new IllegalArgumentException("ttl can't be negative");
 710         if (timeout < 0)
 711             throw new IllegalArgumentException("timeout can't be negative");
 712 
 713         return impl.isReachable(this, timeout, netif, ttl);
 714     }
 715 
 716     /**
 717      * Gets the host name for this IP address.
 718      *
 719      * <p>If this InetAddress was created with a host name,
 720      * this host name will be remembered and returned;
 721      * otherwise, a reverse name lookup will be performed
 722      * and the result will be returned based on the system
 723      * configured resolver. If a lookup of the name service
 724      * is required, call
 725      * {@link #getCanonicalHostName() getCanonicalHostName}.
 726      *
 727      * <p>If there is a security manager, its
 728      * {@code checkConnect} method is first called
 729      * with the hostname and {@code -1}
 730      * as its arguments to see if the operation is allowed.
 731      * If the operation is not allowed, it will return
 732      * the textual representation of the IP address.
 733      *
 734      * @return  the host name for this IP address, or if the operation
 735      *    is not allowed by the security check, the textual
 736      *    representation of the IP address.
 737      *
 738      * @see InetAddress#getCanonicalHostName
 739      * @see SecurityManager#checkConnect
 740      */
 741     public String getHostName() {
 742         return getHostName(true);
 743     }

 804     /**
 805      * Returns the hostname for this address.
 806      *
 807      * <p>If there is a security manager, this method first
 808      * calls its {@code checkConnect} method
 809      * with the hostname and {@code -1}
 810      * as its arguments to see if the calling code is allowed to know
 811      * the hostname for this IP address, i.e., to connect to the host.
 812      * If the operation is not allowed, it will return
 813      * the textual representation of the IP address.
 814      *
 815      * @return  the host name for this IP address, or if the operation
 816      *    is not allowed by the security check, the textual
 817      *    representation of the IP address.
 818      *
 819      * @param check make security check if true
 820      *
 821      * @see SecurityManager#checkConnect
 822      */
 823     private static String getHostFromNameService(InetAddress addr, boolean check) {
 824         String host;
 825         var resolver = resolver();
 826         try {
 827             // first lookup the hostname
 828             host = resolver.lookupHostName(addr.getAddress());
 829 
 830             /* check to see if calling code is allowed to know
 831              * the hostname for this IP address, ie, connect to the host
 832              */
 833             if (check) {
 834                 @SuppressWarnings("removal")
 835                 SecurityManager sec = System.getSecurityManager();
 836                 if (sec != null) {
 837                     sec.checkConnect(host, -1);
 838                 }
 839             }
 840 
 841             /* now get all the IP addresses for this hostname,
 842              * and make sure one of them matches the original IP
 843              * address. We do this to try and prevent spoofing.
 844              */
 845 
 846             InetAddress[] arr = InetAddress.getAllByName0(host, check);
 847             boolean ok = false;
 848 
 849             if (arr != null) {
 850                 for (int i = 0; !ok && i < arr.length; i++) {
 851                     ok = addr.equals(arr[i]);
 852                 }
 853             }
 854 
 855             //XXX: if it looks like a spoof just return the address?
 856             if (!ok) {
 857                 host = addr.getHostAddress();
 858                 return host;
 859             }
 860         } catch (RuntimeException | UnknownHostException e) {


 861             host = addr.getHostAddress();

 862         }
 863         return host;
 864     }
 865 
 866     /**
 867      * Returns the raw IP address of this {@code InetAddress}
 868      * object. The result is in network byte order: the highest order
 869      * byte of the address is in {@code getAddress()[0]}.
 870      *
 871      * @return  the raw IP address of this object.
 872      */
 873     public byte[] getAddress() {
 874         return null;
 875     }
 876 
 877     /**
 878      * Returns the IP address string in textual presentation.
 879      *
 880      * @return  the raw IP address in a string format.
 881      * @since   1.0.2

 901      * <p>
 902      * Two instances of {@code InetAddress} represent the same IP
 903      * address if the length of the byte arrays returned by
 904      * {@code getAddress} is the same for both, and each of the
 905      * array components is the same for the byte arrays.
 906      *
 907      * @param   obj   the object to compare against.
 908      * @return  {@code true} if the objects are the same;
 909      *          {@code false} otherwise.
 910      * @see     java.net.InetAddress#getAddress()
 911      */
 912     public boolean equals(Object obj) {
 913         return false;
 914     }
 915 
 916     /**
 917      * Converts this IP address to a {@code String}. The
 918      * string returned is of the form: hostname / literal IP
 919      * address.
 920      *
 921      * If the host name is unresolved, no reverse lookup
 922      * is performed. The hostname part will be represented
 923      * by an empty string.
 924      *
 925      * @return  a string representation of this IP address.
 926      */
 927     public String toString() {
 928         String hostName = holder().getHostName();
 929         return Objects.toString(hostName, "")
 930             + "/" + getHostAddress();
 931     }
 932 
 933     // mapping from host name to Addresses - either NameServiceAddresses (while
 934     // still being looked-up by NameService(s)) or CachedAddresses when cached
 935     private static final ConcurrentMap<String, Addresses> cache =
 936         new ConcurrentHashMap<>();
 937 
 938     // CachedAddresses that have to expire are kept ordered in this NavigableSet
 939     // which is scanned on each access
 940     private static final NavigableSet<CachedAddresses> expirySet =
 941         new ConcurrentSkipListSet<>();
 942 
 943     // common interface

 968         }
 969 
 970         @Override
 971         public int compareTo(CachedAddresses other) {
 972             // natural order is expiry time -
 973             // compare difference of expiry times rather than
 974             // expiry times directly, to avoid possible overflow.
 975             // (see System.nanoTime() recommendations...)
 976             long diff = this.expiryTime - other.expiryTime;
 977             if (diff < 0L) return -1;
 978             if (diff > 0L) return 1;
 979             // ties are broken using unique id
 980             return Long.compare(this.id, other.id);
 981         }
 982     }
 983 
 984     // a name service lookup based Addresses implementation which replaces itself
 985     // in cache when the result is obtained
 986     private static final class NameServiceAddresses implements Addresses {
 987         private final String host;

 988 
 989         NameServiceAddresses(String host) {
 990             this.host = host;

 991         }
 992 
 993         @Override
 994         public InetAddress[] get() throws UnknownHostException {
 995             Addresses addresses;
 996             // only one thread is doing lookup to name service
 997             // for particular host at any time.
 998             synchronized (this) {
 999                 // re-check that we are still us + re-install us if slot empty
1000                 addresses = cache.putIfAbsent(host, this);
1001                 if (addresses == null) {
1002                     // this can happen when we were replaced by CachedAddresses in
1003                     // some other thread, then CachedAddresses expired and were
1004                     // removed from cache while we were waiting for lock...
1005                     addresses = this;
1006                 }
1007                 // still us ?
1008                 if (addresses == this) {
1009                     // lookup name services
1010                     InetAddress[] inetAddresses;
1011                     UnknownHostException ex;
1012                     int cachePolicy;
1013                     try {
1014                         inetAddresses = getAddressesFromNameService(host);
1015                         ex = null;
1016                         cachePolicy = InetAddressCachePolicy.get();
1017                     } catch (UnknownHostException uhe) {
1018                         inetAddresses = null;
1019                         ex = uhe;
1020                         cachePolicy = InetAddressCachePolicy.getNegative();
1021                     }
1022                     // remove or replace us with cached addresses according to cachePolicy
1023                     if (cachePolicy == InetAddressCachePolicy.NEVER) {
1024                         cache.remove(host, this);
1025                     } else {
1026                         CachedAddresses cachedAddresses = new CachedAddresses(
1027                             host,
1028                             inetAddresses,
1029                             cachePolicy == InetAddressCachePolicy.FOREVER
1030                             ? 0L
1031                             // cachePolicy is in [s] - we need [ns]
1032                             : System.nanoTime() + 1000_000_000L * cachePolicy
1033                         );
1034                         if (cache.replace(host, this, cachedAddresses) &&
1035                             cachePolicy != InetAddressCachePolicy.FOREVER) {
1036                             // schedule expiry
1037                             expirySet.add(cachedAddresses);
1038                         }
1039                     }
1040                     if (inetAddresses == null) {
1041                         throw ex == null ? new UnknownHostException(host) : ex;
1042                     }
1043                     return inetAddresses;
1044                 }
1045                 // else addresses != this
1046             }
1047             // delegate to different addresses when we are already replaced
1048             // but outside of synchronized block to avoid any chance of dead-locking
1049             return addresses.get();
1050         }
1051     }
1052 
1053     /**
1054      * The default InetAddressResolver implementation, which delegates to the underlying































1055      * OS network libraries to resolve host address mappings.
1056      *
1057      * @since 9
1058      */
1059     private static final class PlatformResolver implements InetAddressResolver {
1060 
1061         public Stream<InetAddress> lookupAddresses(String host, LookupPolicy policy)
1062                 throws UnknownHostException {
1063             Objects.requireNonNull(host);
1064             return Arrays.stream(impl.lookupAllHostAddr(host, policy));
1065         }
1066 
1067         public String lookupHostName(byte[] addr)
1068                 throws UnknownHostException {
1069             if (addr.length != Inet4Address.INADDRSZ && addr.length != Inet6Address.INADDRSZ) {
1070                 throw new IllegalArgumentException("Invalid address length");
1071             }
1072             return impl.getHostByAddr(addr);
1073         }
1074     }
1075 
1076     /**
1077      * The HostsFileResolver provides host address mapping
1078      * by reading the entries in a hosts file, which is specified by
1079      * {@code jdk.net.hosts.file} system property
1080      *
1081      * <p>The file format is that which corresponds with the /etc/hosts file
1082      * IP Address host alias list.
1083      *
1084      * <p>When the file lookup is enabled it replaces the default InetAddressResolver
1085      * implementation
1086      *
1087      * @since 9
1088      */
1089     private static final class HostsFileResolver implements InetAddressResolver {






1090 
1091         private final String hostsFile;
1092 
1093         public HostsFileResolver(String hostsFileName) {
1094             this.hostsFile = hostsFileName;
1095         }
1096 
1097         /**
1098          * Lookup the host name  corresponding to the IP address provided.
1099          * Search the configured host file a host name corresponding to
1100          * the specified IP address.
1101          *
1102          * @param addr byte array representing an IP address
1103          * @return {@code String} representing the host name mapping
1104          * @throws UnknownHostException if no host found for the specified IP address
1105          * @throws IllegalArgumentException if IP address is of illegal length
1106          */
1107         @Override
1108         public String lookupHostName(byte[] addr) throws UnknownHostException {
1109             String hostEntry;
1110             String host = null;
1111 
1112             // Check the length of the address array
1113             if (addr.length != Inet4Address.INADDRSZ && addr.length != Inet6Address.INADDRSZ) {
1114                 throw new IllegalArgumentException("Invalid address length");
1115             }
1116 
1117             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
1118                                                         UTF_8.INSTANCE)) {

1119                 while (hostsFileScanner.hasNextLine()) {
1120                     hostEntry = hostsFileScanner.nextLine();
1121                     if (!hostEntry.startsWith("#")) {
1122                         hostEntry = removeComments(hostEntry);
1123                         String[] mapping = hostEntry.split("\\s+");
1124                         if (mapping.length >= 2 &&
1125                             Arrays.equals(addr, createAddressByteArray(mapping[0]))) {
1126                             host = mapping[1];
1127                             break;
1128                         }
1129                     }
1130                 }
1131             } catch (IOException e) {
1132                 throw new UnknownHostException("Unable to resolve address "
1133                         + Arrays.toString(addr) + " as hosts file " + hostsFile
1134                         + " not found ");
1135             }
1136 
1137             if ((host == null) || (host.isEmpty()) || (host.equals(" "))) {
1138                 throw new UnknownHostException("Requested address "
1139                         + Arrays.toString(addr)
1140                         + " resolves to an invalid entry in hosts file "
1141                         + hostsFile);
1142             }
1143             return host;
1144         }
1145 
1146         /**
1147          * <p>Lookup a host mapping by name. Retrieve the IP addresses
1148          * associated with a host.
1149          *
1150          * <p>Search the configured hosts file for the addresses associated
1151          * with the specified host name.
1152          *
1153          * @param host the specified hostname
1154          * @param lookupPolicy IP addresses lookup policy which specifies addresses
1155          *                     family and their order
1156          * @return stream of IP addresses for the requested host
1157          * @throws UnknownHostException
1158          *             if no IP address for the {@code host} could be found
1159          */
1160         public Stream<InetAddress> lookupAddresses(String host, LookupPolicy lookupPolicy)
1161                 throws UnknownHostException {
1162             String hostEntry;
1163             String addrStr;
1164             byte addr[];
1165             List<InetAddress> inetAddresses = new ArrayList<>();
1166             List<InetAddress> inet4Addresses = new ArrayList<>();
1167             List<InetAddress> inet6Addresses = new ArrayList<>();
1168             int flags = lookupPolicy.characteristics();
1169             boolean needIPv4 = (flags & IPv4) != 0;
1170             boolean needIPv6 = (flags & IPv6) != 0;
1171 
1172             Objects.requireNonNull(host);
1173 
1174             // lookup the file and create a list InetAddress for the specified host
1175             try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
1176                     UTF_8.INSTANCE)) {
1177                 while (hostsFileScanner.hasNextLine()) {
1178                     hostEntry = hostsFileScanner.nextLine();
1179                     if (!hostEntry.startsWith("#")) {
1180                         hostEntry = removeComments(hostEntry);
1181                         if (hostEntry.contains(host)) {
1182                             addrStr = extractHostAddr(hostEntry, host);
1183                             if ((addrStr != null) && (!addrStr.isEmpty())) {
1184                                 addr = createAddressByteArray(addrStr);
1185                                 if (addr != null) {
1186                                     InetAddress address = InetAddress.getByAddress(host, addr);
1187                                     inetAddresses.add(address);
1188                                     if (address instanceof Inet4Address && needIPv4) {
1189                                         inet4Addresses.add(address);
1190                                     }
1191                                     if (address instanceof Inet6Address && needIPv6) {
1192                                         inet6Addresses.add(address);
1193                                     }
1194                                 }
1195                             }
1196                         }
1197                     }
1198                 }
1199             } catch (IOException e) {
1200                 throw new UnknownHostException("Unable to resolve host " + host
1201                         + " as hosts file " + hostsFile + " not found ");
1202             }
1203             // Check number of found addresses:
1204             // If none found - throw an exception
1205             boolean noAddressFound = inetAddresses.isEmpty();
1206             // needIPv4 == false and needIPv6 is not a valid combination. See LookupPolicy.of.
1207             if (needIPv4 != needIPv6) {
1208                 if (needIPv4) {
1209                     noAddressFound = inet4Addresses.isEmpty();
1210                 } else {
1211                     noAddressFound = inet6Addresses.isEmpty();
1212                 }



1213             }
1214             if (noAddressFound) {

1215                 throw new UnknownHostException("Unable to resolve host " + host
1216                         + " in hosts file " + hostsFile);
1217             }


1218 
1219             // If both address types are requested
1220             if (needIPv4 == needIPv6) {
1221                 if (systemAddressesOrder(flags)) {
1222                     return inetAddresses.stream();
1223                 } else if (ipv6AddressesFirst(flags)) {
1224                     return Stream.concat(inet6Addresses.stream(), inet4Addresses.stream());
1225                 } else if (ipv4AddressesFirst(flags)) {
1226                     return Stream.concat(inet4Addresses.stream(), inet6Addresses.stream());
1227                 }
1228             }
1229             // Only IPv4 addresses are requested
1230             if (needIPv4) {
1231                 return inet4Addresses.stream();
1232             }
1233             // Only IPv6 addresses are requested
1234             return inet6Addresses.stream();
1235         }
1236 
1237         private String removeComments(String hostsEntry) {
1238             String filteredEntry = hostsEntry;
1239             int hashIndex;
1240 
1241             if ((hashIndex = hostsEntry.indexOf("#")) != -1) {
1242                 filteredEntry = hostsEntry.substring(0, hashIndex);
1243             }
1244             return filteredEntry;
1245         }
1246 
1247         private byte [] createAddressByteArray(String addrStr) {
1248             byte[] addrArray;
1249             // check if IPV4 address - most likely
1250             addrArray = IPAddressUtil.textToNumericFormatV4(addrStr);
1251             if (addrArray == null) {
1252                 addrArray = IPAddressUtil.textToNumericFormatV6(addrStr);
1253             }
1254             return addrArray;

1256 
1257         /** host to ip address mapping */
1258         private String extractHostAddr(String hostEntry, String host) {
1259             String[] mapping = hostEntry.split("\\s+");
1260             String hostAddr = null;
1261 
1262             if (mapping.length >= 2) {
1263                 // look at the host aliases
1264                 for (int i = 1; i < mapping.length; i++) {
1265                     if (mapping[i].equalsIgnoreCase(host)) {
1266                         hostAddr = mapping[0];
1267                     }
1268                 }
1269             }
1270             return hostAddr;
1271         }
1272     }
1273 
1274     static final InetAddressImpl  impl;
1275 
1276     /**
1277      * Platform-wide {@code LookupPolicy} initialized from {@code "java.net.preferIPv4Stack"},
1278      * {@code "java.net.preferIPv6Addresses"} system properties.
1279      */
1280     static final LookupPolicy PLATFORM_LOOKUP_POLICY;
1281 
1282     static {
1283         // create the impl
1284         impl = InetAddressImplFactory.create();
1285 
1286         // impl must be initialized before calling this method
1287         PLATFORM_LOOKUP_POLICY = initializePlatformLookupPolicy();
1288 
1289         // create built-in resolver
1290         BUILTIN_RESOLVER = createBuiltinInetAddressResolver();
1291     }
1292 
1293     /**
1294      * Create an instance of the InetAddressResolver interface based on
1295      * the setting of the {@code jdk.net.hosts.file} system property.
1296      *
1297      * <p>The default InetAddressResolver is the PlatformResolver, which typically
1298      * delegates name and address resolution calls to the underlying
1299      * OS network libraries.
1300      *
1301      * <p> A HostsFileResolver is created if the {@code jdk.net.hosts.file}
1302      * system property is set. If the specified file doesn't exist, the name or
1303      * address lookup will result in an UnknownHostException. Thus, non existent
1304      * hosts file is handled as if the file is empty.
1305      *
1306      * @return an InetAddressResolver
1307      */
1308     private static InetAddressResolver createBuiltinInetAddressResolver() {
1309         InetAddressResolver theResolver;
1310         if (HOSTS_FILE_NAME != null) {
1311             theResolver = new HostsFileResolver(HOSTS_FILE_NAME);



1312         } else {
1313             theResolver = new PlatformResolver();
1314         }
1315         return theResolver;
1316     }
1317 
1318     /**
1319      * Creates an InetAddress based on the provided host name and IP address.
1320      * System {@linkplain InetAddressResolver resolver} is not used to check
1321      * the validity of the address.
1322      *
1323      * <p> The host name can either be a machine name, such as
1324      * "{@code www.example.com}", or a textual representation of its IP
1325      * address.
1326      * <p> No validity checking is done on the host name either.
1327      *
1328      * <p> If addr specifies an IPv4 address an instance of Inet4Address
1329      * will be returned; otherwise, an instance of Inet6Address
1330      * will be returned.
1331      *
1332      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1333      * must be 16 bytes long
1334      *
1335      * @param host the specified host
1336      * @param addr the raw IP address in network byte order
1337      * @return  an InetAddress object created from the raw IP address.
1338      * @throws     UnknownHostException  if IP address is of illegal length
1339      * @since 1.4
1340      */
1341     public static InetAddress getByAddress(String host, byte[] addr)

1384      * section&nbsp;2.5.3.
1385      *
1386      * <p> If there is a security manager, and {@code host} is not {@code null}
1387      * or {@code host.length() } is not equal to zero, the security manager's
1388      * {@code checkConnect} method is called with the hostname and {@code -1}
1389      * as its arguments to determine if the operation is allowed.
1390      *
1391      * @param      host   the specified host, or {@code null}.
1392      * @return     an IP address for the given host name.
1393      * @throws     UnknownHostException  if no IP address for the
1394      *               {@code host} could be found, or if a scope_id was specified
1395      *               for a global IPv6 address.
1396      * @throws     SecurityException if a security manager exists
1397      *             and its checkConnect method doesn't allow the operation
1398      */
1399     public static InetAddress getByName(String host)
1400         throws UnknownHostException {
1401         return InetAddress.getAllByName(host)[0];
1402     }
1403 






1404     /**
1405      * Given the name of a host, returns an array of its IP addresses,
1406      * based on the configured system {@linkplain InetAddressResolver resolver}.
1407      *
1408      * <p> The host name can either be a machine name, such as
1409      * "{@code www.example.com}", or a textual representation of its IP
1410      * address. If a literal IP address is supplied, only the
1411      * validity of the address format is checked.
1412      *
1413      * <p> For {@code host} specified in <i>literal IPv6 address</i>,
1414      * either the form defined in RFC 2732 or the literal IPv6 address
1415      * format defined in RFC 2373 is accepted. A literal IPv6 address may
1416      * also be qualified by appending a scoped zone identifier or scope_id.
1417      * The syntax and usage of scope_ids is described
1418      * <a href="Inet6Address.html#scoped">here</a>.
1419      *
1420      * <p> If the host is {@code null} or {@code host.length()} is equal
1421      * to zero, then an {@code InetAddress} representing an address of the
1422      * loopback interface is returned.
1423      * See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC&nbsp;3330</a>
1424      * section&nbsp;2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC&nbsp;2373</a>
1425      * section&nbsp;2.5.3. </p>
1426      *
1427      * <p> If there is a security manager, and {@code host} is not {@code null}
1428      * or {@code host.length() } is not equal to zero, the security manager's
1429      * {@code checkConnect} method is called with the hostname and {@code -1}
1430      * as its arguments to determine if the operation is allowed.
1431      *
1432      * @param      host   the name of the host, or {@code null}.
1433      * @return     an array of all the IP addresses for a given host name.
1434      *
1435      * @throws     UnknownHostException  if no IP address for the
1436      *               {@code host} could be found, or if a scope_id was specified
1437      *               for a global IPv6 address.
1438      * @throws     SecurityException  if a security manager exists and its
1439      *               {@code checkConnect} method doesn't allow the operation.
1440      *
1441      * @see SecurityManager#checkConnect
1442      */
1443     public static InetAddress[] getAllByName(String host)
1444         throws UnknownHostException {





1445 
1446         if (host == null || host.isEmpty()) {
1447             InetAddress[] ret = new InetAddress[1];
1448             ret[0] = impl.loopbackAddress();
1449             return ret;
1450         }
1451 
1452         boolean ipv6Expected = false;
1453         if (host.charAt(0) == '[') {
1454             // This is supposed to be an IPv6 literal
1455             if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
1456                 host = host.substring(1, host.length() -1);
1457                 ipv6Expected = true;
1458             } else {
1459                 // This was supposed to be a IPv6 address, but it's not!
1460                 throw new UnknownHostException(host + ": invalid IPv6 address");
1461             }
1462         }
1463 
1464         // if host is an IP address, we won't do further lookup

1486                 // Means an IPv4 literal between brackets!
1487                 throw new UnknownHostException("["+host+"]");
1488             }
1489             InetAddress[] ret = new InetAddress[1];
1490             if(addr != null) {
1491                 if (addr.length == Inet4Address.INADDRSZ) {
1492                     ret[0] = new Inet4Address(null, addr);
1493                 } else {
1494                     if (ifname != null) {
1495                         ret[0] = new Inet6Address(null, addr, ifname);
1496                     } else {
1497                         ret[0] = new Inet6Address(null, addr, numericZone);
1498                     }
1499                 }
1500                 return ret;
1501             }
1502         } else if (ipv6Expected) {
1503             // We were expecting an IPv6 Literal, but got something else
1504             throw new UnknownHostException("["+host+"]");
1505         }
1506         return getAllByName0(host, true, true);
1507     }
1508 
1509     /**
1510      * Returns the loopback address.
1511      * <p>
1512      * The InetAddress returned will represent the IPv4
1513      * loopback address, 127.0.0.1, or the IPv6 loopback
1514      * address, ::1. The IPv4 loopback address returned
1515      * is only one of many in the form 127.*.*.*
1516      *
1517      * @return  the InetAddress loopback instance.
1518      * @since 1.7
1519      */
1520     public static InetAddress getLoopbackAddress() {
1521         return impl.loopbackAddress();
1522     }
1523 
1524 
1525     /**
1526      * check if the literal address string has %nn appended

1536         if (percent == -1) {
1537             return -1;
1538         }
1539         for (int i=percent+1; i<slen; i++) {
1540             char c = s.charAt(i);
1541             if (c == ']') {
1542                 if (i == percent+1) {
1543                     /* empty per-cent field */
1544                     return -1;
1545                 }
1546                 break;
1547             }
1548             if ((digit = Character.digit (c, 10)) < 0) {
1549                 return -1;
1550             }
1551             zone = (zone * 10) + digit;
1552         }
1553         return zone;
1554     }
1555 






1556     /**
1557      * package private so SocketPermission can call it
1558      */
1559     static InetAddress[] getAllByName0 (String host, boolean check)
1560         throws UnknownHostException  {
1561         return getAllByName0(host, check, true);
1562     }
1563 
1564     /**
1565      * Designated lookup method.
1566      *
1567      * @param host host name to look up

1568      * @param check perform security check
1569      * @param useCache use cached value if not expired else always
1570      *                 perform name service lookup (and cache the result)
1571      * @return array of InetAddress(es)
1572      * @throws UnknownHostException if host name is not found
1573      */
1574     private static InetAddress[] getAllByName0(String host,

1575                                                boolean check,
1576                                                boolean useCache)
1577         throws UnknownHostException  {
1578 
1579         /* If it gets here it is presumed to be a hostname */
1580 
1581         /* make sure the connection to the host is allowed, before we
1582          * give out a hostname
1583          */
1584         if (check) {
1585             @SuppressWarnings("removal")
1586             SecurityManager security = System.getSecurityManager();
1587             if (security != null) {
1588                 security.checkConnect(host, -1);
1589             }
1590         }
1591 
1592         // remove expired addresses from cache - expirySet keeps them ordered
1593         // by expiry time so we only need to iterate the prefix of the NavigableSet...
1594         long now = System.nanoTime();

1612         // look-up or remove from cache
1613         Addresses addrs;
1614         if (useCache) {
1615             addrs = cache.get(host);
1616         } else {
1617             addrs = cache.remove(host);
1618             if (addrs != null) {
1619                 if (addrs instanceof CachedAddresses) {
1620                     // try removing from expirySet too if CachedAddresses
1621                     expirySet.remove(addrs);
1622                 }
1623                 addrs = null;
1624             }
1625         }
1626 
1627         if (addrs == null) {
1628             // create a NameServiceAddresses instance which will look up
1629             // the name service and install it within cache...
1630             Addresses oldAddrs = cache.putIfAbsent(
1631                 host,
1632                     addrs = new NameServiceAddresses(host)
1633             );
1634             if (oldAddrs != null) { // lost putIfAbsent race
1635                 addrs = oldAddrs;
1636             }
1637         }
1638 
1639         // ask Addresses to get an array of InetAddress(es) and clone it
1640         return addrs.get().clone();
1641     }
1642 
1643     static InetAddress[] getAddressesFromNameService(String host)
1644             throws UnknownHostException {
1645         Stream<InetAddress> addresses = null;
1646         UnknownHostException ex = null;
1647 
1648         var resolver = resolver();
1649         try {
1650             addresses = resolver.lookupAddresses(host, PLATFORM_LOOKUP_POLICY);
1651         } catch (RuntimeException | UnknownHostException x) {
1652             if (host.equalsIgnoreCase("localhost")) {
1653                 addresses = Stream.of(impl.loopbackAddress());
1654             } else if (x instanceof UnknownHostException uhe) {
1655                 ex = uhe;
1656             } else {
1657                 ex = new UnknownHostException();
1658                 ex.initCause(x);
1659             }
1660         }
1661 
1662         if (addresses == null) {
1663             throw ex == null ? new UnknownHostException(host) : ex;
1664         }
1665         return addresses.toArray(InetAddress[]::new);






















1666     }
1667 
1668     /**
1669      * Returns an {@code InetAddress} object given the raw IP address .
1670      * The argument is in network byte order: the highest order
1671      * byte of the address is in {@code getAddress()[0]}.
1672      *
1673      * <p> This method doesn't block, i.e. no reverse lookup is performed.

1674      *
1675      * <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
1676      * must be 16 bytes long
1677      *
1678      * @param addr the raw IP address in network byte order
1679      * @return  an InetAddress object created from the raw IP address.
1680      * @throws     UnknownHostException  if IP address is of illegal length
1681      * @since 1.4
1682      */
1683     public static InetAddress getByAddress(byte[] addr)
1684         throws UnknownHostException {
1685         return getByAddress(null, addr);
1686     }
1687 
1688     private static final class CachedLocalHost {
1689         final String host;
1690         final InetAddress addr;
1691         final long expiryTime = System.nanoTime() + 5000_000_000L; // now + 5s;
1692 
1693         CachedLocalHost(String host, InetAddress addr) {

1732                 if (security != null) {
1733                     security.checkConnect(clh.host, -1);
1734                 }
1735                 return clh.addr;
1736             }
1737 
1738             String local = impl.getLocalHostName();
1739 
1740             if (security != null) {
1741                 security.checkConnect(local, -1);
1742             }
1743 
1744             InetAddress localAddr;
1745             if (local.equals("localhost")) {
1746                 // shortcut for "localhost" host name
1747                 localAddr = impl.loopbackAddress();
1748             } else {
1749                 // call getAllByName0 without security checks and
1750                 // without using cached data
1751                 try {
1752                     localAddr = getAllByName0(local, false, false)[0];
1753                 } catch (UnknownHostException uhe) {
1754                     // Rethrow with a more informative error message.
1755                     UnknownHostException uhe2 =
1756                         new UnknownHostException(local + ": " +
1757                                                  uhe.getMessage());
1758                     uhe2.initCause(uhe);
1759                     throw uhe2;
1760                 }
1761             }
1762             cachedLocalHost = new CachedLocalHost(local, localAddr);
1763             return localAddr;
1764         } catch (java.lang.SecurityException e) {
1765             return impl.loopbackAddress();
1766         }
1767     }
1768 
1769     /**
1770      * Perform class load-time initializations.
1771      */
1772     private static native void init();
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