/*

 * Copyright (c) 1995, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package java.net;

import java.util.NavigableSet;

import java.util.ArrayList;

import java.util.Objects;

import java.util.Scanner;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.ObjectStreamException;

import java.io.ObjectStreamField;

import java.io.IOException;

import java.io.InvalidObjectException;

import java.io.ObjectInputStream;

import java.io.ObjectInputStream.GetField;

import java.io.ObjectOutputStream;

import java.io.ObjectOutputStream.PutField;

import java.lang.annotation.Native;

import java.util.ServiceLoader;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ConcurrentMap;

import java.util.concurrent.ConcurrentSkipListSet;

import java.util.concurrent.atomic.AtomicLong;

import java.util.Arrays;

import jdk.internal.misc.VM;

import jdk.internal.access.JavaNetInetAddressAccess;

import jdk.internal.access.SharedSecrets;

import sun.security.action.*;

import sun.net.InetAddressCachePolicy;

import sun.net.util.IPAddressUtil;

/**

 * This class represents an Internet Protocol (IP) address.

 *

 * <p> An IP address is either a 32-bit or 128-bit unsigned number

 * used by IP, a lower-level protocol on which protocols like UDP and

 * TCP are built. The IP address architecture is defined by <a

 * href="http://www.ietf.org/rfc/rfc790.txt"><i>RFC&nbsp;790:

 * Assigned Numbers</i></a>, <a

 * href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC&nbsp;1918:

 * Address Allocation for Private Internets</i></a>, <a

 * href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC&nbsp;2365:

 * Administratively Scoped IP Multicast</i></a>, and <a

 * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC&nbsp;2373: IP

 * Version 6 Addressing Architecture</i></a>. An instance of an

 * InetAddress consists of an IP address and possibly its

 * corresponding host name (depending on whether it is constructed

 * with a host name or whether it has already done reverse host name

 * resolution).

 *

 * <h2> Address types </h2>

 *

 * <table class="striped" style="margin-left:2em">

 *   <caption style="display:none">Description of unicast and multicast address types</caption>

 *   <thead>

 *   <tr><th scope="col">Address Type</th><th scope="col">Description</th></tr>

 *   </thead>

 *   <tbody>

 *   <tr><th scope="row" style="vertical-align:top">unicast</th>

 *       <td>An identifier for a single interface. A packet sent to

 *         a unicast address is delivered to the interface identified by

 *         that address.

 *

 *         <p> The Unspecified Address -- Also called anylocal or wildcard

 *         address. It must never be assigned to any node. It indicates the

 *         absence of an address. One example of its use is as the target of

 *         bind, which allows a server to accept a client connection on any

 *         interface, in case the server host has multiple interfaces.

 *

 *         <p> The <i>unspecified</i> address must not be used as

 *         the destination address of an IP packet.

 *

 *         <p> The <i>Loopback</i> Addresses -- This is the address

 *         assigned to the loopback interface. Anything sent to this

 *         IP address loops around and becomes IP input on the local

 *         host. This address is often used when testing a

 *         client.</td></tr>

 *   <tr><th scope="row" style="vertical-align:top">multicast</th>

 *       <td>An identifier for a set of interfaces (typically belonging

 *         to different nodes). A packet sent to a multicast address is

 *         delivered to all interfaces identified by that address.</td></tr>

 * </tbody>

 * </table>

 *

 * <h3> IP address scope </h3>

 *

 * <p> <i>Link-local</i> addresses are designed to be used for addressing

 * on a single link for purposes such as auto-address configuration,

 * neighbor discovery, or when no routers are present.

 *

 * <p> <i>Site-local</i> addresses are designed to be used for addressing

 * inside of a site without the need for a global prefix.

 *

 * <p> <i>Global</i> addresses are unique across the internet.

 *

 * <h3> Textual representation of IP addresses </h3>

 *

 * The textual representation of an IP address is address family specific.

 *

 * <p>

 *

 * For IPv4 address format, please refer to <A

 * HREF="Inet4Address.html#format">Inet4Address#format</A>; For IPv6

 * address format, please refer to <A

 * HREF="Inet6Address.html#format">Inet6Address#format</A>.

 *

 * <P>There is a <a href="doc-files/net-properties.html#Ipv4IPv6">couple of

 * System Properties</a> affecting how IPv4 and IPv6 addresses are used.</P>

 *

 * <h3> Host Name Resolution </h3>

 *

 * Host name-to-IP address <i>resolution</i> is accomplished through

 * the use of a combination of local machine configuration information

 * and network naming services such as the Domain Name System (DNS)

 * and Network Information Service(NIS). The particular naming

 * services(s) being used is by default the local machine configured

 * one. For any host name, its corresponding IP address is returned.

 *

 * <p> <i>Reverse name resolution</i> means that for any IP address,

 * the host associated with the IP address is returned.

 *

 * <p> The InetAddress class provides methods to resolve host names to

 * their IP addresses and vice versa.

 *

 * <h3> InetAddress Caching </h3>

 *

 * The InetAddress class has a cache to store successful as well as

 * unsuccessful host name resolutions.

 *

 * <p> By default, when a security manager is installed, in order to

 * protect against DNS spoofing attacks,

 * the result of positive host name resolutions are

 * cached forever. When a security manager is not installed, the default

 * behavior is to cache entries for a finite (implementation dependent)

 * period of time. The result of unsuccessful host

 * name resolution is cached for a very short period of time (10

 * seconds) to improve performance.

 *

 * <p> If the default behavior is not desired, then a Java security property

 * can be set to a different Time-to-live (TTL) value for positive

 * caching. Likewise, a system admin can configure a different

 * negative caching TTL value when needed.

 *

 * <p> Two Java security properties control the TTL values used for

 *  positive and negative host name resolution caching:

 *

 * <dl style="margin-left:2em">

 * <dt><b>networkaddress.cache.ttl</b></dt>

 * <dd>Indicates the caching policy for successful name lookups from

 * the name service. The value is specified as an integer to indicate

 * the number of seconds to cache the successful lookup. The default

 * setting is to cache for an implementation specific period of time.

 * <p>

 * A value of -1 indicates "cache forever".

 * </dd>

 * <dt><b>networkaddress.cache.negative.ttl</b> (default: 10)</dt>

 * <dd>Indicates the caching policy for un-successful name lookups

 * from the name service. The value is specified as an integer to

 * indicate the number of seconds to cache the failure for

 * un-successful lookups.

 * <p>

 * A value of 0 indicates "never cache".

 * A value of -1 indicates "cache forever".

 * </dd>

 * </dl>

 *

 * @author  Chris Warth

 * @see     java.net.InetAddress#getByAddress(byte[])

 * @see     java.net.InetAddress#getByAddress(java.lang.String, byte[])

 * @see     java.net.InetAddress#getAllByName(java.lang.String)

 * @see     java.net.InetAddress#getByName(java.lang.String)

 * @see     java.net.InetAddress#getLocalHost()

 * @since 1.0

 */

public

class InetAddress implements java.io.Serializable {

    @Native static final int PREFER_IPV4_VALUE = 0;

    @Native static final int PREFER_IPV6_VALUE = 1;

    @Native static final int PREFER_SYSTEM_VALUE = 2;

    /**

     * Specify the address family: Internet Protocol, Version 4

     * @since 1.4

     */

    @Native static final int IPv4 = 1;

    /**

     * Specify the address family: Internet Protocol, Version 6

     * @since 1.4

     */

    @Native static final int IPv6 = 2;

    /* Specify address family preference */

    static transient final int preferIPv6Address;

    static class InetAddressHolder {

        /**

         * Reserve the original application specified hostname.

         *

         * The original hostname is useful for domain-based endpoint

         * identification (see RFC 2818 and RFC 6125).  If an address

         * was created with a raw IP address, a reverse name lookup

         * may introduce endpoint identification security issue via

         * DNS forging.

         *

         * Oracle JSSE provider is using this original hostname, via

         * jdk.internal.misc.JavaNetAccess, for SSL/TLS endpoint identification.

         *

         * Note: May define a new public method in the future if necessary.

         */

        String originalHostName;

        InetAddressHolder() {}

        InetAddressHolder(String hostName, int address, int family) {

            this.originalHostName = hostName;

            this.hostName = hostName;

            this.address = address;

            this.family = family;

        }

        void init(String hostName, int family) {

            this.originalHostName = hostName;

            this.hostName = hostName;

            if (family != -1) {

                this.family = family;

            }

        }

        String hostName;

        String getHostName() {

            return hostName;

        }

        String getOriginalHostName() {

            return originalHostName;

        }

        /**

         * Holds a 32-bit IPv4 address.

         */

        int address;

        int getAddress() {

            return address;

        }

        /**

         * Specifies the address family type, for instance, '1' for IPv4

         * addresses, and '2' for IPv6 addresses.

         */

        int family;

        int getFamily() {

            return family;

        }

    }

    /* Used to store the serializable fields of InetAddress */

    final transient InetAddressHolder holder;

    InetAddressHolder holder() {

        return holder;

    }

    /* Used to store the name service provider */

    private static transient NameService nameService;

    private static transient NameService defaultNameService;

    /**

     * Used to store the best available hostname.

     * Lazily initialized via a data race; safe because Strings are immutable.

     */

    private transient String canonicalHostName = null;

    /** use serialVersionUID from JDK 1.0.2 for interoperability */

    @java.io.Serial

    private static final long serialVersionUID = 3286316764910316507L;

    /*

     * Load net library into runtime, and perform initializations.

     */

    static {

        String str = GetPropertyAction.privilegedGetProperty("java.net.preferIPv6Addresses");

        if (str == null) {

            preferIPv6Address = PREFER_IPV4_VALUE;

        } else if (str.equalsIgnoreCase("true")) {

            preferIPv6Address = PREFER_IPV6_VALUE;

        } else if (str.equalsIgnoreCase("false")) {

            preferIPv6Address = PREFER_IPV4_VALUE;

        } else if (str.equalsIgnoreCase("system")) {

            preferIPv6Address = PREFER_SYSTEM_VALUE;

        } else {

            preferIPv6Address = PREFER_IPV4_VALUE;

        }

        jdk.internal.loader.BootLoader.loadLibrary("net");

        SharedSecrets.setJavaNetInetAddressAccess(

                new JavaNetInetAddressAccess() {

                    public String getOriginalHostName(InetAddress ia) {

                        return ia.holder.getOriginalHostName();

                    }

                    public InetAddress getByName(String hostName,

                                                 InetAddress hostAddress)

                            throws UnknownHostException

                    {

                        return InetAddress.getByName(hostName, hostAddress);

                    }

                }

        );

        init();

    }

    private static NameService nameService() {

        if (nameService != null) {

            return nameService;

        }

        if (VM.isBooted()) {

            synchronized (NameService.class) {

                if (nameService != null) {

                    return nameService;

                }

                return nameService;

            }

        } else {

            return defaultNameService;

        }

    }

    /**

     * Constructor for the Socket.accept() method.

     * This creates an empty InetAddress, which is filled in by

     * the accept() method.  This InetAddress, however, is not

     * put in the address cache, since it is not created by name.

     */

    InetAddress() {

        holder = new InetAddressHolder();

    }

    /**

     * Replaces the de-serialized object with an Inet4Address object.

     *

     * @return the alternate object to the de-serialized object.

     *

     * @throws ObjectStreamException if a new object replacing this

     * object could not be created

     */

    @java.io.Serial

    private Object readResolve() throws ObjectStreamException {

        // will replace the deserialized 'this' object

        return new Inet4Address(holder().getHostName(), holder().getAddress());

    }

    /**

     * Utility routine to check if the InetAddress is an

     * IP multicast address.

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

     * an IP multicast address

     * @since   1.1

     */

    public boolean isMulticastAddress() {

        return false;

    }

    /**

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

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

     *         a wildcard address.

     * @since 1.4

     */

    public boolean isAnyLocalAddress() {

        return false;

    }

    /**

     * 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.

     * @since 1.4

     */

    public boolean isLoopbackAddress() {

        return false;

    }

    /**

     * Utility routine to check if the InetAddress is an link local address.

     *

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

     * a link local address; or false if address is not a link local unicast address.

     * @since 1.4

     */

    public boolean isLinkLocalAddress() {

        return false;

    }

    /**

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

     *

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

     * a site local address; or false if address is not a site local unicast address.

     * @since 1.4

     */

    public boolean isSiteLocalAddress() {

        return false;

    }

    /**

     * Utility routine to check if the multicast address has global scope.

     *

     * @return a {@code boolean} indicating if the address has

     *         is a multicast address of global scope, false if it is not

     *         of global scope or it is not a multicast address

     * @since 1.4

     */

    public boolean isMCGlobal() {

        return false;

    }

    /**

     * Utility routine to check if the multicast address has node scope.

     *

     * @return a {@code boolean} indicating if the address has

     *         is a multicast address of node-local scope, false if it is not

     *         of node-local scope or it is not a multicast address

     * @since 1.4

     */

    public boolean isMCNodeLocal() {

        return false;

    }

    /**

     * Utility routine to check if the multicast address has link scope.

     *

     * @return a {@code boolean} indicating if the address has

     *         is a multicast address of link-local scope, false if it is not

     *         of link-local scope or it is not a multicast address

     * @since 1.4

     */

    public boolean isMCLinkLocal() {

        return false;

    }

    /**

     * Utility routine to check if the multicast address has site scope.

     *

     * @return a {@code boolean} indicating if the address has

     *         is a multicast address of site-local scope, false if it is not

     *         of site-local scope or it is not a multicast address

     * @since 1.4

     */

    public boolean isMCSiteLocal() {

        return false;

    }

    /**

     * Utility routine to check if the multicast address has organization scope.

     *

     * @return a {@code boolean} indicating if the address has

     *         is a multicast address of organization-local scope,

     *         false if it is not of organization-local scope

     *         or it is not a multicast address

     * @since 1.4

     */

    public boolean isMCOrgLocal() {

        return false;

    }

    /**

     * Test whether that address is reachable. Best effort is made by the

     * implementation to try to reach the host, but firewalls and server

     * configuration may block requests resulting in a unreachable status