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   25   
   26   package java.net;
   27   
   28   import java.io.ObjectInputStream;
   29   import java.io.IOException;
   30   import java.io.InvalidObjectException;
   31   import java.util.Enumeration;
   32   
   33   /**
   34    * This class represents an Internet Protocol version 6 (IPv6) address.
   35    * Defined by <a href="http://www.ietf.org/rfc/rfc2373.txt">
   36    * <i>RFC&nbsp;2373: IP Version 6 Addressing Architecture</i></a>.
   37    *
   38    * <h4> <A NAME="format">Textual representation of IP addresses</a> </h4>
   39    *
   40    * Textual representation of IPv6 address used as input to methods
   41    * takes one of the following forms:
   42    *
   43    * <ol>
   44    *   <li><p> <A NAME="lform">The preferred form</a> is x:x:x:x:x:x:x:x,
   45    *   where the 'x's are
   46    *   the hexadecimal values of the eight 16-bit pieces of the
   47    *   address. This is the full form.  For example,
   48    *
   49    *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">
   50    *   <tr><td><tt>1080:0:0:0:8:800:200C:417A</tt><td></tr>
   51    *   </table></blockquote>
   52    *
   53    *   <p> Note that it is not necessary to write the leading zeros in
   54    *   an individual field. However, there must be at least one numeral
   55    *   in every field, except as described below.</li>
   56    *
   57    *   <li><p> Due to some methods of allocating certain styles of IPv6
   58    *   addresses, it will be common for addresses to contain long
   59    *   strings of zero bits. In order to make writing addresses
   60    *   containing zero bits easier, a special syntax is available to
   61    *   compress the zeros. The use of "::" indicates multiple groups
   62    *   of 16-bits of zeros. The "::" can only appear once in an address.
   63    *   The "::" can also be used to compress the leading and/or trailing
   64    *   zeros in an address. For example,
   65    *
   66    *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">
   67    *   <tr><td><tt>1080::8:800:200C:417A</tt><td></tr>
   68    *   </table></blockquote>
   69    *
   70    *   <li><p> An alternative form that is sometimes more convenient
   71    *   when dealing with a mixed environment of IPv4 and IPv6 nodes is
   72    *   x:x:x:x:x:x:d.d.d.d, where the 'x's are the hexadecimal values
   73    *   of the six high-order 16-bit pieces of the address, and the 'd's
   74    *   are the decimal values of the four low-order 8-bit pieces of the
   75    *   standard IPv4 representation address, for example,
   76    *
   77    *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">
   78    *   <tr><td><tt>::FFFF:129.144.52.38</tt><td></tr>
   79    *   <tr><td><tt>::129.144.52.38</tt><td></tr>
   80    *   </table></blockquote>
   81    *
   82    *   <p> where "::FFFF:d.d.d.d" and "::d.d.d.d" are, respectively, the
   83    *   general forms of an IPv4-mapped IPv6 address and an
   84    *   IPv4-compatible IPv6 address. Note that the IPv4 portion must be
   85    *   in the "d.d.d.d" form. The following forms are invalid:
   86    *
   87    *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">
   88    *   <tr><td><tt>::FFFF:d.d.d</tt><td></tr>
   89    *   <tr><td><tt>::FFFF:d.d</tt><td></tr>
   90    *   <tr><td><tt>::d.d.d</tt><td></tr>
   91    *   <tr><td><tt>::d.d</tt><td></tr>
   92    *   </table></blockquote>
   93    *
   94    *   <p> The following form:
   95    *
   96    *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">
   97    *   <tr><td><tt>::FFFF:d</tt><td></tr>
   98    *   </table></blockquote>
   99    *
  100    *   <p> is valid, however it is an unconventional representation of
  101    *   the IPv4-compatible IPv6 address,
  102    *
  103    *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">
  104    *   <tr><td><tt>::255.255.0.d</tt><td></tr>
  105    *   </table></blockquote>
  106    *
  107    *   <p> while "::d" corresponds to the general IPv6 address
  108    *   "0:0:0:0:0:0:0:d".</li>
  109    * </ol>
  110    *
  111    * <p> For methods that return a textual representation as output
  112    * value, the full form is used. Inet6Address will return the full
  113    * form because it is unambiguous when used in combination with other
  114    * textual data.
  115    *
  116    * <h4> Special IPv6 address </h4>
  117    *
  118    * <blockquote>
  119    * <table cellspacing=2 summary="Description of IPv4-mapped address"> <tr><th valign=top><i>IPv4-mapped address</i></th>
  120    *         <td>Of the form::ffff:w.x.y.z, this IPv6 address is used to
  121    *         represent an IPv4 address. It allows the native program to
  122    *         use the same address data structure and also the same
  123    *         socket when communicating with both IPv4 and IPv6 nodes.
  124    *
  125    *         <p>In InetAddress and Inet6Address, it is used for internal
  126    *         representation; it has no functional role. Java will never
  127    *         return an IPv4-mapped address.  These classes can take an
  128    *         IPv4-mapped address as input, both in byte array and text
  129    *         representation. However, it will be converted into an IPv4
  130    *         address.</td></tr>
  131    * </table></blockquote>
  132    * <p>
  133    * <h4> <A NAME="scoped">Textual representation of IPv6 scoped addresses</a> </h4>
  134    * <p>
  135    * The textual representation of IPv6 addresses as described above can be extended
  136    * to specify IPv6 scoped addresses. This extension to the basic addressing architecture
  137    * is described in [draft-ietf-ipngwg-scoping-arch-04.txt].
  138    * <p>
  139    * Because link-local and site-local addresses are non-global, it is possible that different hosts
  140    * may have the same destination address and may be reachable through different interfaces on the
  141    * same originating system. In this case, the originating system is said to be connected
  142    * to multiple zones of the same scope. In order to disambiguate which is the intended destination
  143    * zone, it is possible to append a zone identifier (or <i>scope_id</i>) to an IPv6 address.
  144    * <p>
  145    * The general format for specifying the <i>scope_id</i> is the following:
  146    * <p><blockquote><i>IPv6-address</i>%<i>scope_id</i></blockquote>
  147    * <p> The IPv6-address is a literal IPv6 address as described above.
  148    * The <i>scope_id</i> refers to an interface on the local system, and it can be specified
  149    * in two ways.
  150    * <p><ol><li><i>As a numeric identifier.</i> This must be a positive integer that identifies the
  151    * particular interface and scope as understood by the system. Usually, the numeric
  152    * values can be determined through administration tools on the system. Each interface may
  153    * have multiple values, one for each scope. If the scope is unspecified, then the default value
  154    * used is zero.</li><p>
  155    * <li><i>As a string.</i> This must be the exact string that is returned by
  156    * {@link java.net.NetworkInterface#getName()} for the particular interface in question.
  157    * When an Inet6Address is created in this way, the numeric scope-id is determined at the time
  158    * the object is created by querying the relevant NetworkInterface.</li>
  159    * </ol><p>
  160    * Note also, that the numeric <i>scope_id</i> can be retrieved from Inet6Address instances returned from the
  161    * NetworkInterface class. This can be used to find out the current scope ids configured on the system.
  162    * @since 1.4
  163    */
  164   
  165   public final
  166   class Inet6Address extends InetAddress {
  167       final static int INADDRSZ = 16;
  168   
  169       /*
  170        * cached scope_id - for link-local address use only.
  171        */
  172       private transient int cached_scope_id = 0;
  173   
  174       /**
  175        * Holds a 128-bit (16 bytes) IPv6 address.
  176        *
  177        * @serial
  178        */
  179       byte[] ipaddress;
  180   
  181       /**
  182        * scope_id. The scope specified when the object is created. If the object is created
  183        * with an interface name, then the scope_id is not determined until the time it is needed.
  184        */
  185       private int scope_id = 0;
  186   
  187       /**
  188        * This will be set to true when the scope_id field contains a valid
  189        * integer scope_id.
  190        */
  191       private boolean scope_id_set = false;
  192   
  193       /**
  194        * scoped interface. scope_id is derived from this as the scope_id of the first
  195        * address whose scope is the same as this address for the named interface.
  196        */
  197       private transient NetworkInterface scope_ifname = null;
  198   
  199       /**
  200        * set if the object is constructed with a scoped interface instead of a
  201        * numeric scope id.
  202        */
  203       private boolean scope_ifname_set = false;
  204   
  205       private static final long serialVersionUID = 6880410070516793377L;
  206   
  207       /*
  208        * Perform initializations.
  209        */
  210       static {
  211           init();
  212       }
  213   
  214       Inet6Address() {
  215           super();
  216           hostName = null;
  217           ipaddress = new byte[INADDRSZ];
  218           family = IPv6;
  219       }
  220   
  221       /* checking of value for scope_id should be done by caller
  222        * scope_id must be >= 0, or -1 to indicate not being set
  223        */
  224       Inet6Address(String hostName, byte addr[], int scope_id) {
  225           this.hostName = hostName;
  226           if (addr.length == INADDRSZ) { // normal IPv6 address
  227               family = IPv6;
  228               ipaddress = addr.clone();
  229           }
  230           if (scope_id >= 0) {
  231               this.scope_id = scope_id;
  232               scope_id_set = true;
  233           }
  234       }
  235   
  236       Inet6Address(String hostName, byte addr[]) {
  237           try {
  238               initif (hostName, addr, null);
  239           } catch (UnknownHostException e) {} /* cant happen if ifname is null */
  240       }
  241   
  242       Inet6Address (String hostName, byte addr[], NetworkInterface nif) throws UnknownHostException {
  243           initif (hostName, addr, nif);
  244       }
  245   
  246       Inet6Address (String hostName, byte addr[], String ifname) throws UnknownHostException {
  247           initstr (hostName, addr, ifname);
  248       }
  249   
  250       /**
  251        * Create an Inet6Address in the exact manner of {@link InetAddress#getByAddress(String,byte[])}
  252        * except that the IPv6 scope_id is set to the value corresponding to the given interface
  253        * for the address type specified in <code>addr</code>.
  254        * The call will fail with an UnknownHostException if the given interface does not have a numeric
  255        * scope_id assigned for the given address type (eg. link-local or site-local).
  256        * See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
  257        * scoped addresses.
  258        *
  259        * @param host the specified host
  260        * @param addr the raw IP address in network byte order
  261        * @param nif an interface this address must be associated with.
  262        * @return  an Inet6Address object created from the raw IP address.
  263        * @exception  UnknownHostException  if IP address is of illegal length, or if the interface
  264        *          does not have a numeric scope_id assigned for the given address type.
  265        *
  266        * @since 1.5
  267        */
  268   
  269       public static Inet6Address getByAddress(String host, byte[] addr, NetworkInterface nif)
  270           throws UnknownHostException {
  271           if (host != null && host.length() > 0 && host.charAt(0) == '[') {
  272               if (host.charAt(host.length()-1) == ']') {
  273                   host = host.substring(1, host.length() -1);
  274               }
  275           }
  276           if (addr != null) {
  277               if (addr.length == Inet6Address.INADDRSZ) {
  278                   return new Inet6Address(host, addr, nif);
  279               }
  280           }
  281           throw new UnknownHostException("addr is of illegal length");
  282       }
  283   
  284       /**
  285        * Create an Inet6Address in the exact manner of {@link InetAddress#getByAddress(String,byte[])}
  286        * except that the IPv6 scope_id is set to the given numeric value.
  287        * The scope_id is not checked to determine if it corresponds to any interface on the system.
  288        * See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
  289        * scoped addresses.
  290        *
  291        * @param host the specified host
  292        * @param addr the raw IP address in network byte order
  293        * @param scope_id the numeric scope_id for the address.
  294        * @return  an Inet6Address object created from the raw IP address.
  295        * @exception  UnknownHostException  if IP address is of illegal length.
  296        *
  297        * @since 1.5
  298        */
  299   
  300       public static Inet6Address getByAddress(String host, byte[] addr, int scope_id)
  301           throws UnknownHostException {
  302           if (host != null && host.length() > 0 && host.charAt(0) == '[') {
  303               if (host.charAt(host.length()-1) == ']') {
  304                   host = host.substring(1, host.length() -1);
  305               }
  306           }
  307           if (addr != null) {
  308               if (addr.length == Inet6Address.INADDRSZ) {
  309                   return new Inet6Address(host, addr, scope_id);
  310               }
  311           }
  312           throw new UnknownHostException("addr is of illegal length");
  313       }
  314   
  315       private void initstr (String hostName, byte addr[], String ifname) throws UnknownHostException {
  316           try {
  317               NetworkInterface nif = NetworkInterface.getByName (ifname);
  318               if (nif == null) {
  319                   throw new UnknownHostException ("no such interface " + ifname);
  320               }
  321               initif (hostName, addr, nif);
  322           } catch (SocketException e) {
  323               throw new UnknownHostException ("SocketException thrown" + ifname);
  324           }
  325       }
  326   
  327       private void initif(String hostName, byte addr[],NetworkInterface nif) throws UnknownHostException {
  328           this.hostName = hostName;
  329           if (addr.length == INADDRSZ) { // normal IPv6 address
  330               family = IPv6;
  331               ipaddress = addr.clone();
  332           }
  333           if (nif != null) {
  334               this.scope_ifname = nif;
  335               scope_ifname_set = true;
  336               scope_id = deriveNumericScope (nif);
  337               scope_id_set = true;
  338           }
  339       }
  340   
  341       /* check the two Ipv6 addresses and return false if they are both
  342        * non global address types, but not the same.
  343        * (ie. one is sitelocal and the other linklocal)
  344        * return true otherwise.
  345        */
  346       private boolean differentLocalAddressTypes(Inet6Address other) {
  347   
  348           if (isLinkLocalAddress() && !other.isLinkLocalAddress()) {
  349               return false;
  350           }
  351           if (isSiteLocalAddress() && !other.isSiteLocalAddress()) {
  352               return false;
  353           }
  354           return true;
  355       }
  356   
  357       private int deriveNumericScope (NetworkInterface ifc) throws UnknownHostException {
  358           Enumeration<InetAddress> addresses = ifc.getInetAddresses();
  359           while (addresses.hasMoreElements()) {
  360               InetAddress addr = addresses.nextElement();
  361               if (!(addr instanceof Inet6Address)) {
  362                   continue;
  363               }
  364               Inet6Address ia6_addr = (Inet6Address)addr;
  365               /* check if site or link local prefixes match */
  366               if (!differentLocalAddressTypes(ia6_addr)){
  367                   /* type not the same, so carry on searching */
  368                   continue;
  369               }
  370               /* found a matching address - return its scope_id */
  371               return ia6_addr.scope_id;
  372           }
  373           throw new UnknownHostException ("no scope_id found");
  374       }
  375   
  376       private int deriveNumericScope (String ifname) throws UnknownHostException {
  377           Enumeration<NetworkInterface> en;
  378           try {
  379               en = NetworkInterface.getNetworkInterfaces();
  380           } catch (SocketException e) {
  381               throw new UnknownHostException ("could not enumerate local network interfaces");
  382           }
  383           while (en.hasMoreElements()) {
  384               NetworkInterface ifc = en.nextElement();
  385               if (ifc.getName().equals (ifname)) {
  386                   Enumeration addresses = ifc.getInetAddresses();
  387                   while (addresses.hasMoreElements()) {
  388                       InetAddress addr = (InetAddress)addresses.nextElement();
  389                       if (!(addr instanceof Inet6Address)) {
  390                           continue;
  391                       }
  392                       Inet6Address ia6_addr = (Inet6Address)addr;
  393                       /* check if site or link local prefixes match */
  394                       if (!differentLocalAddressTypes(ia6_addr)){
  395                           /* type not the same, so carry on searching */
  396                           continue;
  397                       }
  398                       /* found a matching address - return its scope_id */
  399                       return ia6_addr.scope_id;
  400                   }
  401               }
  402           }
  403           throw new UnknownHostException ("No matching address found for interface : " +ifname);
  404       }
  405   
  406       /**
  407        * restore the state of this object from stream
  408        * including the scope information, only if the
  409        * scoped interface name is valid on this system
  410        */
  411       private void readObject(ObjectInputStream s)
  412           throws IOException, ClassNotFoundException {
  413           scope_ifname = null;
  414           scope_ifname_set = false;
  415           s.defaultReadObject();
  416   
  417           if (ifname != null && !"".equals (ifname)) {
  418               try {
  419                   scope_ifname = NetworkInterface.getByName(ifname);
  420                   if (scope_ifname == null) {
  421                       /* the interface does not exist on this system, so we clear
  422                        * the scope information completely */
  423                       scope_id_set = false;
  424                       scope_ifname_set = false;
  425                       scope_id = 0;
  426                   } else {
  427                       try {
  428                           scope_id = deriveNumericScope (scope_ifname);
  429                       } catch (UnknownHostException e) {
  430                           // typically should not happen, but it may be that
  431                           // the machine being used for deserialization has
  432                           // the same interface name but without IPv6 configured.
  433                       }
  434                   }
  435               } catch (SocketException e) {}
  436   
  437           }
  438           /* if ifname was not supplied, then the numeric info is used */
  439   
  440           ipaddress = ipaddress.clone();
  441   
  442           // Check that our invariants are satisfied
  443           if (ipaddress.length != INADDRSZ) {
  444               throw new InvalidObjectException("invalid address length: "+
  445                                                ipaddress.length);
  446           }
  447   
  448           if (family != IPv6) {
  449               throw new InvalidObjectException("invalid address family type");
  450           }
  451       }
  452   
  453       /**
  454        * Utility routine to check if the InetAddress is an IP multicast
  455        * address. 11111111 at the start of the address identifies the
  456        * address as being a multicast address.
  457        *
  458        * @return a <code>boolean</code> indicating if the InetAddress is
  459        * an IP multicast address
  460        * @since JDK1.1
  461        */
  462       @Override
  463       public boolean isMulticastAddress() {
  464           return ((ipaddress[0] & 0xff) == 0xff);
  465       }
  466   
  467       /**
  468        * Utility routine to check if the InetAddress in a wildcard address.
  469        * @return a <code>boolean</code> indicating if the Inetaddress is
  470        *         a wildcard address.
  471        * @since 1.4
  472        */
  473       @Override
  474       public boolean isAnyLocalAddress() {
  475           byte test = 0x00;
  476           for (int i = 0; i < INADDRSZ; i++) {
  477               test |= ipaddress[i];
  478           }
  479           return (test == 0x00);
  480       }
  481   
  482       /**
  483        * Utility routine to check if the InetAddress is a loopback address.
  484        *
  485        * @return a <code>boolean</code> indicating if the InetAddress is
  486        * a loopback address; or false otherwise.
  487        * @since 1.4
  488        */
  489       @Override
  490       public boolean isLoopbackAddress() {
  491           byte test = 0x00;
  492           for (int i = 0; i < 15; i++) {
  493               test |= ipaddress[i];
  494           }
  495           return (test == 0x00) && (ipaddress[15] == 0x01);
  496       }
  497   
  498       /**
  499        * Utility routine to check if the InetAddress is an link local address.
  500        *
  501        * @return a <code>boolean</code> indicating if the InetAddress is
  502        * a link local address; or false if address is not a link local unicast address.
  503        * @since 1.4
  504        */
  505       @Override
  506       public boolean isLinkLocalAddress() {
  507           return ((ipaddress[0] & 0xff) == 0xfe
  508                   && (ipaddress[1] & 0xc0) == 0x80);
  509       }
  510   
  511       /**
  512        * Utility routine to check if the InetAddress is a site local address.
  513        *
  514        * @return a <code>boolean</code> indicating if the InetAddress is
  515        * a site local address; or false if address is not a site local unicast address.
  516        * @since 1.4
  517        */
  518       @Override
  519       public boolean isSiteLocalAddress() {
  520           return ((ipaddress[0] & 0xff) == 0xfe
  521                   && (ipaddress[1] & 0xc0) == 0xc0);
  522       }
  523   
  524       /**
  525        * Utility routine to check if the multicast address has global scope.
  526        *
  527        * @return a <code>boolean</code> indicating if the address has
  528        *         is a multicast address of global scope, false if it is not
  529        *         of global scope or it is not a multicast address
  530        * @since 1.4
  531        */
  532       @Override
  533       public boolean isMCGlobal() {
  534           return ((ipaddress[0] & 0xff) == 0xff
  535                   && (ipaddress[1] & 0x0f) == 0x0e);
  536       }
  537   
  538       /**
  539        * Utility routine to check if the multicast address has node scope.
  540        *
  541        * @return a <code>boolean</code> indicating if the address has
  542        *         is a multicast address of node-local scope, false if it is not
  543        *         of node-local scope or it is not a multicast address
  544        * @since 1.4
  545        */
  546       @Override
  547       public boolean isMCNodeLocal() {
  548           return ((ipaddress[0] & 0xff) == 0xff
  549                   && (ipaddress[1] & 0x0f) == 0x01);
  550       }
  551   
  552       /**
  553        * Utility routine to check if the multicast address has link scope.
  554        *
  555        * @return a <code>boolean</code> indicating if the address has
  556        *         is a multicast address of link-local scope, false if it is not
  557        *         of link-local scope or it is not a multicast address
  558        * @since 1.4
  559        */
  560       @Override
  561       public boolean isMCLinkLocal() {
  562           return ((ipaddress[0] & 0xff) == 0xff
  563                   && (ipaddress[1] & 0x0f) == 0x02);
  564       }
  565   
  566       /**
  567        * Utility routine to check if the multicast address has site scope.
  568        *
  569        * @return a <code>boolean</code> indicating if the address has
  570        *         is a multicast address of site-local scope, false if it is not
  571        *         of site-local scope or it is not a multicast address
  572        * @since 1.4
  573        */
  574       @Override
  575       public boolean isMCSiteLocal() {
  576           return ((ipaddress[0] & 0xff) == 0xff
  577                   && (ipaddress[1] & 0x0f) == 0x05);
  578       }
  579   
  580       /**
  581        * Utility routine to check if the multicast address has organization scope.
  582        *
  583        * @return a <code>boolean</code> indicating if the address has
  584        *         is a multicast address of organization-local scope,
  585        *         false if it is not of organization-local scope
  586        *         or it is not a multicast address
  587        * @since 1.4
  588        */
  589       @Override
  590       public boolean isMCOrgLocal() {
  591           return ((ipaddress[0] & 0xff) == 0xff
  592                   && (ipaddress[1] & 0x0f) == 0x08);
  593       }
  594   
  595       /**
  596        * Returns the raw IP address of this <code>InetAddress</code>
  597        * object. The result is in network byte order: the highest order
  598        * byte of the address is in <code>getAddress()[0]</code>.
  599        *
  600        * @return  the raw IP address of this object.
  601        */
  602       @Override
  603       public byte[] getAddress() {
  604           return ipaddress.clone();
  605       }
  606   
  607       /**
  608        * Returns the numeric scopeId, if this instance is associated with
  609        * an interface. If no scoped_id is set, the returned value is zero.
  610        *
  611        * @return the scopeId, or zero if not set.
  612        * @since 1.5
  613        */
  614        public int getScopeId () {
  615           return scope_id;
  616        }
  617   
  618       /**
  619        * Returns the scoped interface, if this instance was created with
  620        * with a scoped interface.
  621        *
  622        * @return the scoped interface, or null if not set.
  623        * @since 1.5
  624        */
  625        public NetworkInterface getScopedInterface () {
  626           return scope_ifname;
  627        }
  628   
  629       /**
  630        * Returns the IP address string in textual presentation. If the instance was created
  631        * specifying a scope identifier then the scope id is appended to the IP address preceded by
  632        * a "%" (per-cent) character. This can be either a numeric value or a string, depending on which
  633        * was used to createthe instance.
  634        *
  635        * @return  the raw IP address in a string format.
  636        */
  637       @Override
  638       public String getHostAddress() {
  639           String s = numericToTextFormat(ipaddress);
  640           if (scope_ifname_set) { /* must check this first */
  641               s = s + "%" + scope_ifname.getName();
  642           } else if (scope_id_set) {
  643               s = s + "%" + scope_id;
  644           }
  645           return s;
  646       }
  647   
  648       /**
  649        * Returns a hashcode for this IP address.
  650        *
  651        * @return  a hash code value for this IP address.
  652        */
  653       @Override
  654       public int hashCode() {
  655           if (ipaddress != null) {
  656   
  657               int hash = 0;
  658               int i=0;
  659               while (i<INADDRSZ) {
  660                   int j=0;
  661                   int component=0;
  662                   while (j<4 && i<INADDRSZ) {
  663                       component = (component << 8) + ipaddress[i];
  664                       j++;
  665                       i++;
  666                   }
  667                   hash += component;
  668               }
  669               return hash;
  670   
  671           } else {
  672               return 0;
  673           }
  674       }
  675   
  676       /**
  677        * Compares this object against the specified object.
  678        * The result is <code>true</code> if and only if the argument is
  679        * not <code>null</code> and it represents the same IP address as
  680        * this object.
  681        * <p>
  682        * Two instances of <code>InetAddress</code> represent the same IP
  683        * address if the length of the byte arrays returned by
  684        * <code>getAddress</code> is the same for both, and each of the
  685        * array components is the same for the byte arrays.
  686        *
  687        * @param   obj   the object to compare against.
  688        * @return  <code>true</code> if the objects are the same;
  689        *          <code>false</code> otherwise.
  690        * @see     java.net.InetAddress#getAddress()
  691        */
  692       @Override
  693       public boolean equals(Object obj) {
  694           if (obj == null ||
  695               !(obj instanceof Inet6Address))
  696               return false;
  697   
  698           Inet6Address inetAddr = (Inet6Address)obj;
  699   
  700           for (int i = 0; i < INADDRSZ; i++) {
  701               if (ipaddress[i] != inetAddr.ipaddress[i])
  702                   return false;
  703           }
  704   
  705           return true;
  706       }
  707   
  708       /**
  709        * Utility routine to check if the InetAddress is an
  710        * IPv4 compatible IPv6 address.
  711        *
  712        * @return a <code>boolean</code> indicating if the InetAddress is
  713        * an IPv4 compatible IPv6 address; or false if address is IPv4 address.
  714        * @since 1.4
  715        */
  716       public boolean isIPv4CompatibleAddress() {
  717           if ((ipaddress[0] == 0x00) && (ipaddress[1] == 0x00) &&
  718               (ipaddress[2] == 0x00) && (ipaddress[3] == 0x00) &&
  719               (ipaddress[4] == 0x00) && (ipaddress[5] == 0x00) &&
  720               (ipaddress[6] == 0x00) && (ipaddress[7] == 0x00) &&
  721               (ipaddress[8] == 0x00) && (ipaddress[9] == 0x00) &&
  722               (ipaddress[10] == 0x00) && (ipaddress[11] == 0x00))  {
  723               return true;
  724           }
  725           return false;
  726       }
  727   
  728       // Utilities
  729       private final static int INT16SZ = 2;
  730       /*
  731        * Convert IPv6 binary address into presentation (printable) format.
  732        *
  733        * @param src a byte array representing the IPv6 numeric address
  734        * @return a String representing an IPv6 address in
  735        *         textual representation format
  736        * @since 1.4
  737        */
  738       static String numericToTextFormat(byte[] src)
  739       {
  740           StringBuffer sb = new StringBuffer(39);
  741           for (int i = 0; i < (INADDRSZ / INT16SZ); i++) {
  742               sb.append(Integer.toHexString(((src[i<<1]<<8) & 0xff00)
  743                                             | (src[(i<<1)+1] & 0xff)));
  744               if (i < (INADDRSZ / INT16SZ) -1 ) {
  745                  sb.append(":");
  746               }
  747           }
  748           return sb.toString();
  749       }
  750   
  751       /**
  752        * Perform class load-time initializations.
  753        */
  754       private static native void init();
  755   
  756       /**
  757        * Following field is only used during (de)/serialization
  758        */
  759       private String ifname;
  760   
  761       /**
  762        * default behavior is overridden in order to write the
  763        * scope_ifname field as a String, rather than a NetworkInterface
  764        * which is not serializable
  765        */
  766       private synchronized void writeObject(java.io.ObjectOutputStream s)
  767           throws IOException
  768       {
  769           if (scope_ifname_set) {
  770               ifname = scope_ifname.getName();
  771           }
  772           s.defaultWriteObject();
  773       }
  774   }

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