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 * accompanied this code).

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package java.net;

import java.io.IOException;

import java.io.InvalidObjectException;

import java.io.ObjectInputStream;

import java.util.Enumeration;

/**

 * This class represents an Internet Protocol version 6 (IPv6) address.

 * Defined by <a href="http://www.ietf.org/rfc/rfc2373.txt">

 * <i>RFC&nbsp;2373: IP Version 6 Addressing Architecture</i></a>.

 *

 * <h4> <A NAME="format">Textual representation of IP addresses</a> </h4>

 *

 * Textual representation of IPv6 address used as input to methods

 * takes one of the following forms:

 *

 * <ol>

 *   <li><p> <A NAME="lform">The preferred form</a> is x:x:x:x:x:x:x:x,

 *   where the 'x's are

 *   the hexadecimal values of the eight 16-bit pieces of the

 *   address. This is the full form.  For example,

 *

 *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">

 *   <tr><td><tt>1080:0:0:0:8:800:200C:417A</tt><td></tr>

 *   </table></blockquote>

 *

 *   <p> Note that it is not necessary to write the leading zeros in

 *   an individual field. However, there must be at least one numeral

 *   in every field, except as described below.</li>

 *

 *   <li><p> Due to some methods of allocating certain styles of IPv6

 *   addresses, it will be common for addresses to contain long

 *   strings of zero bits. In order to make writing addresses

 *   containing zero bits easier, a special syntax is available to

 *   compress the zeros. The use of "::" indicates multiple groups

 *   of 16-bits of zeros. The "::" can only appear once in an address.

 *   The "::" can also be used to compress the leading and/or trailing

 *   zeros in an address. For example,

 *

 *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">

 *   <tr><td><tt>1080::8:800:200C:417A</tt><td></tr>

 *   </table></blockquote>

 *

 *   <li><p> An alternative form that is sometimes more convenient

 *   when dealing with a mixed environment of IPv4 and IPv6 nodes is

 *   x:x:x:x:x:x:d.d.d.d, where the 'x's are the hexadecimal values

 *   of the six high-order 16-bit pieces of the address, and the 'd's

 *   are the decimal values of the four low-order 8-bit pieces of the

 *   standard IPv4 representation address, for example,

 *

 *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">

 *   <tr><td><tt>::FFFF:129.144.52.38</tt><td></tr>

 *   <tr><td><tt>::129.144.52.38</tt><td></tr>

 *   </table></blockquote>

 *

 *   <p> where "::FFFF:d.d.d.d" and "::d.d.d.d" are, respectively, the

 *   general forms of an IPv4-mapped IPv6 address and an

 *   IPv4-compatible IPv6 address. Note that the IPv4 portion must be

 *   in the "d.d.d.d" form. The following forms are invalid:

 *

 *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">

 *   <tr><td><tt>::FFFF:d.d.d</tt><td></tr>

 *   <tr><td><tt>::FFFF:d.d</tt><td></tr>

 *   <tr><td><tt>::d.d.d</tt><td></tr>

 *   <tr><td><tt>::d.d</tt><td></tr>

 *   </table></blockquote>

 *

 *   <p> The following form:

 *

 *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">

 *   <tr><td><tt>::FFFF:d</tt><td></tr>

 *   </table></blockquote>

 *

 *   <p> is valid, however it is an unconventional representation of

 *   the IPv4-compatible IPv6 address,

 *

 *   <blockquote><table cellpadding=0 cellspacing=0 summary="layout">

 *   <tr><td><tt>::255.255.0.d</tt><td></tr>

 *   </table></blockquote>

 *

 *   <p> while "::d" corresponds to the general IPv6 address

 *   "0:0:0:0:0:0:0:d".</li>

 * </ol>

 *

 * <p> For methods that return a textual representation as output

 * value, the full form is used. Inet6Address will return the full

 * form because it is unambiguous when used in combination with other

 * textual data.

 *

 * <h4> Special IPv6 address </h4>

 *

 * <blockquote>

 * <table cellspacing=2 summary="Description of IPv4-mapped address">

 * <tr><th valign=top><i>IPv4-mapped address</i></th>

 *         <td>Of the form::ffff:w.x.y.z, this IPv6 address is used to

 *         represent an IPv4 address. It allows the native program to

 *         use the same address data structure and also the same

 *         socket when communicating with both IPv4 and IPv6 nodes.

 *

 *         <p>In InetAddress and Inet6Address, it is used for internal

 *         representation; it has no functional role. Java will never

 *         return an IPv4-mapped address.  These classes can take an

 *         IPv4-mapped address as input, both in byte array and text

 *         representation. However, it will be converted into an IPv4

 *         address.</td></tr>

 * </table></blockquote>

 * <p>

 * <h4><A NAME="scoped">Textual representation of IPv6 scoped addresses</a></h4>

 *

 * <p> The textual representation of IPv6 addresses as described above can be

 * extended to specify IPv6 scoped addresses. This extension to the basic

 * addressing architecture is described in [draft-ietf-ipngwg-scoping-arch-04.txt].

 *

 * <p> Because link-local and site-local addresses are non-global, it is possible

 * that different hosts may have the same destination address and may be

 * reachable through different interfaces on the same originating system. In

 * this case, the originating system is said to be connected to multiple zones

 * of the same scope. In order to disambiguate which is the intended destination

 * zone, it is possible to append a zone identifier (or <i>scope_id</i>) to an

 * IPv6 address.

 *

 * <p> The general format for specifying the <i>scope_id</i> is the following:

 *

 * <p><blockquote><i>IPv6-address</i>%<i>scope_id</i></blockquote>

 * <p> The IPv6-address is a literal IPv6 address as described above.

 * The <i>scope_id</i> refers to an interface on the local system, and it can be

 * specified in two ways.

 * <p><ol><li><i>As a numeric identifier.</i> This must be a positive integer

 * that identifies the particular interface and scope as understood by the

 * system. Usually, the numeric values can be determined through administration

 * tools on the system. Each interface may have multiple values, one for each

 * scope. If the scope is unspecified, then the default value used is zero.</li>

 * <p><li><i>As a string.</i> This must be the exact string that is returned by

 * {@link java.net.NetworkInterface#getName()} for the particular interface in

 * question. When an Inet6Address is created in this way, the numeric scope-id

 * is determined at the time the object is created by querying the relevant

 * NetworkInterface.</li></ol>

 *

 * <p> Note also, that the numeric <i>scope_id</i> can be retrieved from

 * Inet6Address instances returned from the NetworkInterface class. This can be

 * used to find out the current scope ids configured on the system.

 * @since 1.4

 */

public final

class Inet6Address extends InetAddress {

    final static int INADDRSZ = 16;

    /*

     * cached scope_id - for link-local address use only.

     */

    private transient int cached_scope_id;  // 0

    /**

     * Holds a 128-bit (16 bytes) IPv6 address.

     *

     * @serial

     */

    byte[] ipaddress;

    /**

     * scope_id. The scope specified when the object is created. If the object

     * is created with an interface name, then the scope_id is not determined

     * until the time it is needed.

     */

    private int scope_id;  // 0

    /**

     * This will be set to true when the scope_id field contains a valid

     * integer scope_id.

     */

    private boolean scope_id_set;  // false

    /**

     * scoped interface. scope_id is derived from this as the scope_id of the first

     * address whose scope is the same as this address for the named interface.

     */

    private transient NetworkInterface scope_ifname;  // null

    private static final long serialVersionUID = 6880410070516793377L;

    // Perform native initialization

    static { init(); }

    Inet6Address() {

        super();

        holder().hostName = null;

        ipaddress = new byte[INADDRSZ];

        holder().family = IPv6;

    }

    /* checking of value for scope_id should be done by caller

     * scope_id must be >= 0, or -1 to indicate not being set

     */

    Inet6Address(String hostName, byte addr[], int scope_id) {

        holder().hostName = hostName;

        if (addr.length == INADDRSZ) { // normal IPv6 address

            holder().family = IPv6;

            ipaddress = addr.clone();

        }

        if (scope_id >= 0) {

            this.scope_id = scope_id;

            scope_id_set = true;

        }

    }

    Inet6Address(String hostName, byte addr[]) {

        try {

            initif (hostName, addr, null);

        } catch (UnknownHostException e) {} /* cant happen if ifname is null */

    }

    Inet6Address (String hostName, byte addr[], NetworkInterface nif)

        throws UnknownHostException

    {

        initif (hostName, addr, nif);

    }

    Inet6Address (String hostName, byte addr[], String ifname)

        throws UnknownHostException

    {

        initstr (hostName, addr, ifname);

    }

    /**

     * Create an Inet6Address in the exact manner of {@link

     * InetAddress#getByAddress(String,byte[])} except that the IPv6 scope_id is

     * set to the value corresponding to the given interface for the address

     * type specified in <code>addr</code>. The call will fail with an

     * UnknownHostException if the given interface does not have a numeric

     * scope_id assigned for the given address type (eg. link-local or site-local).

     * See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6

     * scoped addresses.

     *

     * @param host the specified host

     * @param addr the raw IP address in network byte order

     * @param nif an interface this address must be associated with.

     * @return  an Inet6Address object created from the raw IP address.

     * @throws  UnknownHostException

     *          if IP address is of illegal length, or if the interface does not

     *          have a numeric scope_id assigned for the given address type.

     *

     * @since 1.5

     */

    public static Inet6Address getByAddress(String host, byte[] addr,

                                            NetworkInterface nif)

        throws UnknownHostException

    {

        if (host != null && host.length() > 0 && host.charAt(0) == '[') {

            if (host.charAt(host.length()-1) == ']') {

                host = host.substring(1, host.length() -1);

            }

        }

        if (addr != null) {

            if (addr.length == Inet6Address.INADDRSZ) {

                return new Inet6Address(host, addr, nif);

            }

        }

        throw new UnknownHostException("addr is of illegal length");

    }

    /**

     * Create an Inet6Address in the exact manner of {@link

     * InetAddress#getByAddress(String,byte[])} except that the IPv6 scope_id is

     * set to the given numeric value. The scope_id is not checked to determine

     * if it corresponds to any interface on the system.

     * See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6

     * scoped addresses.

     *

     * @param host the specified host

     * @param addr the raw IP address in network byte order

     * @param scope_id the numeric scope_id for the address.

     * @return  an Inet6Address object created from the raw IP address.

     * @throws  UnknownHostException  if IP address is of illegal length.

     *

     * @since 1.5

     */

    public static Inet6Address getByAddress(String host, byte[] addr,

                                            int scope_id)

        throws UnknownHostException

    {

        if (host != null && host.length() > 0 && host.charAt(0) == '[') {

            if (host.charAt(host.length()-1) == ']') {

                host = host.substring(1, host.length() -1);

            }

        }

        if (addr != null) {

            if (addr.length == Inet6Address.INADDRSZ) {

                return new Inet6Address(host, addr, scope_id);

            }

        }

        throw new UnknownHostException("addr is of illegal length");

    }

    private void initstr(String hostName, byte addr[], String ifname)

        throws UnknownHostException

    {

        try {

            NetworkInterface nif = NetworkInterface.getByName (ifname);

            if (nif == null) {

                throw new UnknownHostException ("no such interface " + ifname);

            }

            initif (hostName, addr, nif);

        } catch (SocketException e) {

            throw new UnknownHostException ("SocketException thrown" + ifname);

        }

    }

        throws UnknownHostException

    {

        holder().hostName = hostName;

        if (addr.length == INADDRSZ) { // normal IPv6 address

            holder().family = IPv6;

            ipaddress = addr.clone();

        }

        if (nif != null) {

            scope_ifname = nif;

            scope_id = deriveNumericScope(nif);

            scope_id_set = true;

        }

    }

    /* check the two Ipv6 addresses and return false if they are both

     * non global address types, but not the same.

     * (ie. one is sitelocal and the other linklocal)

     * return true otherwise.

     */

    private boolean differentLocalAddressTypes(Inet6Address other) {

        if (isLinkLocalAddress() && !other.isLinkLocalAddress())

            return false;

        if (isSiteLocalAddress() && !other.isSiteLocalAddress())

            return false;

        return true;

    }

    private int deriveNumericScope(NetworkInterface ifc)

        throws UnknownHostException

    {

        Enumeration<InetAddress> addresses = ifc.getInetAddresses();

        while (addresses.hasMoreElements()) {

            InetAddress addr = addresses.nextElement();

            if (!(addr instanceof Inet6Address)) {

                continue;

            }

            Inet6Address ia6_addr = (Inet6Address)addr;

            /* check if site or link local prefixes match */

            if (!differentLocalAddressTypes(ia6_addr)){

                /* type not the same, so carry on searching */

                continue;

            }

            /* found a matching address - return its scope_id */

            return ia6_addr.scope_id;

        }

        throw new UnknownHostException ("no scope_id found");

    }

    private int deriveNumericScope(String ifname) throws UnknownHostException {

        Enumeration<NetworkInterface> en;

        try {

            en = NetworkInterface.getNetworkInterfaces();

        } catch (SocketException e) {

            throw new UnknownHostException(

                    "could not enumerate local network interfaces");

        }

        while (en.hasMoreElements()) {

            NetworkInterface ifc = en.nextElement();

            if (ifc.getName().equals(ifname)) {

                Enumeration<InetAddress> addresses = ifc.getInetAddresses();

                while (addresses.hasMoreElements()) {

                    InetAddress addr = addresses.nextElement();

                    if (!(addr instanceof Inet6Address)) {

                        continue;

                    }

                    Inet6Address ia6_addr = (Inet6Address)addr;

                    /* check if site or link local prefixes match */

                    if (!differentLocalAddressTypes(ia6_addr)){

                        /* type not the same, so carry on searching */

                        continue;

                    }

                    /* found a matching address - return its scope_id */

                    return ia6_addr.scope_id;

                }

            }

        }

        throw new UnknownHostException(

                "No matching address found for interface : " +ifname);

    }

    /**

     * restore the state of this object from stream

     * including the scope information, only if the

     * scoped interface name is valid on this system

     */

    private void readObject(ObjectInputStream s)

        throws IOException, ClassNotFoundException {

        if (getClass().getClassLoader() != null) {

            throw new SecurityException ("invalid address type");

        }

        s.defaultReadObject();

        if (ifname != null && !ifname.equals("")) {

            try {

                scope_ifname = NetworkInterface.getByName(ifname);

                if (scope_ifname != null) {

                    try {

                        scope_id = deriveNumericScope(scope_ifname);

                    } catch (UnknownHostException e) {

                        // typically should not happen, but it may be that

                        // the machine being used for deserialization has

                        // the same interface name but without IPv6 configured.

                    }

                }

            } catch (SocketException e) {}

        }

        /* if ifname was not supplied, then the numeric info is used */

        ipaddress = ipaddress.clone();

        // Check that our invariants are satisfied

        if (ipaddress.length != INADDRSZ) {

            throw new InvalidObjectException("invalid address length: "+

                                             ipaddress.length);

        }

        if (holder().getFamily() != IPv6) {

            throw new InvalidObjectException("invalid address family type");

        }

    }

    /**

     * Utility routine to check if the InetAddress is an IP multicast

     * address. 11111111 at the start of the address identifies the

     * address as being a multicast address.

     *

     * @return a {@code boolean} indicating if the InetAddress is an IP

     *         multicast address

     *

     * @since JDK1.1

     */

    @Override

    public boolean isMulticastAddress() {

        return ((ipaddress[0] & 0xff) == 0xff);

    }

    /**

     * Utility routine to check if the InetAddress in a wildcard address.

     *

     * @return a {@code boolean} indicating if the Inetaddress is

     *         a wildcard address.

     *

     * @since 1.4

     */

    @Override

    public boolean isAnyLocalAddress() {

        byte test = 0x00;

        for (int i = 0; i < INADDRSZ; i++) {

            test |= ipaddress[i];

        }

        return (test == 0x00);

    }

    /**

     * Utility routine to check if the InetAddress is a loopback address.

     *

     * @return a {@code boolean} indicating if the InetAddress is a loopback

     *         address; or false otherwise.