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	/*
	* Copyright (c) 1995, 2021, 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.net;

	import java.util.List;
	import java.util.NavigableSet;
	import java.util.ArrayList;
	import java.util.Objects;
	import java.util.Scanner;
	import java.io.File;
	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.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.access.JavaNetInetAddressAccess;
	import jdk.internal.access.SharedSecrets;
	import sun.security.action.*;
	import sun.net.InetAddressCachePolicy;
	import sun.net.util.IPAddressUtil;
	import sun.nio.cs.UTF_8;

	/**
	* 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 790:
	* Assigned Numbers</i></a>, <a
	* href="http://www.ietf.org/rfc/rfc1918.txt"> <i>RFC 1918:
	* Address Allocation for Private Internets</i></a>, <a
	* href="http://www.ietf.org/rfc/rfc2365.txt"><i>RFC 2365:
	* Administratively Scoped IP Multicast</i></a>, and <a
	* href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC 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;

	/**
	* 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);
	}

	public int addressValue(Inet4Address inet4Address) {
	return inet4Address.addressValue();
	}

	public byte[] addressBytes(Inet6Address inet6Address) {
	return inet6Address.addressBytes();
	}
	}
	);
	init();
	}

	/**
	* 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
	* while some specific ports may be accessible.
	* A typical implementation will use ICMP ECHO REQUESTs if the
	* privilege can be obtained, otherwise it will try to establish
	* a TCP connection on port 7 (Echo) of the destination host.
	* <p>
	* The timeout value, in milliseconds, indicates the maximum amount of time
	* the try should take. If the operation times out before getting an
	* answer, the host is deemed unreachable. A negative value will result
	* in an IllegalArgumentException being thrown.
	*
	* @param timeout the time, in milliseconds, before the call aborts
	* @return a {@code boolean} indicating if the address is reachable.
	* @throws IOException if a network error occurs
	* @throws IllegalArgumentException if {@code timeout} is negative.
	* @since 1.5
	*/
	public boolean isReachable(int timeout) throws IOException {
	return isReachable(null, 0 , timeout);
	}

	/**
	* 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
	* while some specific ports may be accessible.
	* A typical implementation will use ICMP ECHO REQUESTs if the
	* privilege can be obtained, otherwise it will try to establish
	* a TCP connection on port 7 (Echo) of the destination host.
	* <p>
	* The {@code network interface} and {@code ttl} parameters
	* let the caller specify which network interface the test will go through
	* and the maximum number of hops the packets should go through.
	* A negative value for the {@code ttl} will result in an
	* IllegalArgumentException being thrown.
	* <p>
	* The timeout value, in milliseconds, indicates the maximum amount of time
	* the try should take. If the operation times out before getting an
	* answer, the host is deemed unreachable. A negative value will result
	* in an IllegalArgumentException being thrown.
	*
	* @param netif the NetworkInterface through which the
	* test will be done, or null for any interface
	* @param ttl the maximum numbers of hops to try or 0 for the
	* default
	* @param timeout the time, in milliseconds, before the call aborts
	* @throws IllegalArgumentException if either {@code timeout}
	* or {@code ttl} are negative.
	* @return a {@code boolean} indicating if the address is reachable.
	* @throws IOException if a network error occurs
	* @since 1.5
	*/
	public boolean isReachable(NetworkInterface netif, int ttl,
	int timeout) throws IOException {
	if (ttl < 0)
	throw new IllegalArgumentException("ttl can't be negative");
	if (timeout < 0)
	throw new IllegalArgumentException("timeout can't be negative");

	return impl.isReachable(this, timeout, netif, ttl);
	}

	/**
	* Gets the host name for this IP address.
	*
	* <p>If this InetAddress was created with a host name,
	* this host name will be remembered and returned;
	* otherwise, a reverse name lookup will be performed
	* and the result will be returned based on the system
	* configured name lookup service. If a lookup of the name service
	* is required, call
	* {@link #getCanonicalHostName() getCanonicalHostName}.
	*
	* <p>If there is a security manager, its
	* {@code checkConnect} method is first called
	* with the hostname and {@code -1}
	* as its arguments to see if the operation is allowed.
	* If the operation is not allowed, it will return
	* the textual representation of the IP address.
	*
	* @return the host name for this IP address, or if the operation
	* is not allowed by the security check, the textual
	* representation of the IP address.
	*
	* @see InetAddress#getCanonicalHostName
	* @see SecurityManager#checkConnect
	*/
	public String getHostName() {
	return getHostName(true);
	}

	/**
	* Returns the hostname for this address.
	* If the host is equal to null, then this address refers to any
	* of the local machine's available network addresses.
	* this is package private so SocketPermission can make calls into
	* here without a security check.
	*
	* <p>If there is a security manager, this method first
	* calls its {@code checkConnect} method
	* with the hostname and {@code -1}
	* as its arguments to see if the calling code is allowed to know
	* the hostname for this IP address, i.e., to connect to the host.
	* If the operation is not allowed, it will return
	* the textual representation of the IP address.
	*
	* @return the host name for this IP address, or if the operation
	* is not allowed by the security check, the textual
	* representation of the IP address.
	*
	* @param check make security check if true
	*
	* @see SecurityManager#checkConnect
	*/
	String getHostName(boolean check) {
	if (holder().getHostName() == null) {
	holder().hostName = InetAddress.getHostFromNameService(this, check);
	}
	return holder().getHostName();
	}

	/**
	* Gets the fully qualified domain name for this IP address.
	* Best effort method, meaning we may not be able to return
	* the FQDN depending on the underlying system configuration.
	*
	* <p>If there is a security manager, this method first
	* calls its {@code checkConnect} method
	* with the hostname and {@code -1}
	* as its arguments to see if the calling code is allowed to know
	* the hostname for this IP address, i.e., to connect to the host.
	* If the operation is not allowed, it will return
	* the textual representation of the IP address.
	*
	* @return the fully qualified domain name for this IP address,
	* or if the operation is not allowed by the security check,
	* the textual representation of the IP address.
	*
	* @see SecurityManager#checkConnect
	*
	* @since 1.4
	*/
	public String getCanonicalHostName() {
	String value = canonicalHostName;
	if (value == null)
	canonicalHostName = value =
	InetAddress.getHostFromNameService(this, true);
	return value;
	}

	/**
	* Returns the hostname for this address.
	*
	* <p>If there is a security manager, this method first
	* calls its {@code checkConnect} method
	* with the hostname and {@code -1}
	* as its arguments to see if the calling code is allowed to know
	* the hostname for this IP address, i.e., to connect to the host.
	* If the operation is not allowed, it will return
	* the textual representation of the IP address.
	*
	* @return the host name for this IP address, or if the operation
	* is not allowed by the security check, the textual
	* representation of the IP address.
	*
	* @param check make security check if true
	*
	* @see SecurityManager#checkConnect
	*/
	private static String getHostFromNameService(InetAddress addr, boolean check) {
	String host = null;
	try {
	// first lookup the hostname
	host = nameService.getHostByAddr(addr.getAddress());

	/* check to see if calling code is allowed to know
	* the hostname for this IP address, ie, connect to the host
	*/
	if (check) {
	@SuppressWarnings("removal")
	SecurityManager sec = System.getSecurityManager();
	if (sec != null) {
	sec.checkConnect(host, -1);
	}
	}

	/* now get all the IP addresses for this hostname,
	* and make sure one of them matches the original IP
	* address. We do this to try and prevent spoofing.
	*/

	InetAddress[] arr = InetAddress.getAllByName0(host, check);
	boolean ok = false;

	if(arr != null) {
	for(int i = 0; !ok && i < arr.length; i++) {
	ok = addr.equals(arr[i]);
	}
	}

	//XXX: if it looks a spoof just return the address?
	if (!ok) {
	host = addr.getHostAddress();
	return host;
	}
	} catch (SecurityException e) {
	host = addr.getHostAddress();
	} catch (UnknownHostException e) {
	host = addr.getHostAddress();
	// let next provider resolve the hostname
	}
	return host;
	}

	/**
	* Returns the raw IP address of this {@code InetAddress}
	* object. The result is in network byte order: the highest order
	* byte of the address is in {@code getAddress()[0]}.
	*
	* @return the raw IP address of this object.
	*/
	public byte[] getAddress() {
	return null;
	}

	/**
	* Returns the IP address string in textual presentation.
	*
	* @return the raw IP address in a string format.
	* @since 1.0.2
	*/
	public String getHostAddress() {
	return null;
	}

	/**
	* Returns a hashcode for this IP address.
	*
	* @return a hash code value for this IP address.
	*/
	public int hashCode() {
	return -1;
	}

	/**
	* Compares this object against the specified object.
	* The result is {@code true} if and only if the argument is
	* not {@code null} and it represents the same IP address as
	* this object.
	* <p>
	* Two instances of {@code InetAddress} represent the same IP
	* address if the length of the byte arrays returned by
	* {@code getAddress} is the same for both, and each of the
	* array components is the same for the byte arrays.
	*
	* @param obj the object to compare against.
	* @return {@code true} if the objects are the same;
	* {@code false} otherwise.
	* @see java.net.InetAddress#getAddress()
	*/
	public boolean equals(Object obj) {
	return false;
	}

	/**
	* Converts this IP address to a {@code String}. The
	* string returned is of the form: hostname / literal IP
	* address.
	*
	* If the host name is unresolved, no reverse name service lookup
	* is performed. The hostname part will be represented by an empty string.
	*
	* @return a string representation of this IP address.
	*/
	public String toString() {
	String hostName = holder().getHostName();
	return Objects.toString(hostName, "")
	+ "/" + getHostAddress();
	}

	// mapping from host name to Addresses - either NameServiceAddresses (while
	// still being looked-up by NameService(s)) or CachedAddresses when cached
	private static final ConcurrentMap<String, Addresses> cache =
	new ConcurrentHashMap<>();

	// CachedAddresses that have to expire are kept ordered in this NavigableSet
	// which is scanned on each access
	private static final NavigableSet<CachedAddresses> expirySet =
	new ConcurrentSkipListSet<>();

	// common interface
	private interface Addresses {
	InetAddress[] get() throws UnknownHostException;
	}

	// a holder for cached addresses with required metadata
	private static final class CachedAddresses implements Addresses, Comparable<CachedAddresses> {
	private static final AtomicLong seq = new AtomicLong();
	final String host;
	final InetAddress[] inetAddresses;
	final long expiryTime; // time of expiry (in terms of System.nanoTime())
	final long id = seq.incrementAndGet(); // each instance is unique

	CachedAddresses(String host, InetAddress[] inetAddresses, long expiryTime) {
	this.host = host;
	this.inetAddresses = inetAddresses;
	this.expiryTime = expiryTime;
	}

	@Override
	public InetAddress[] get() throws UnknownHostException {
	if (inetAddresses == null) {
	throw new UnknownHostException(host);
	}
	return inetAddresses;
	}

	@Override
	public int compareTo(CachedAddresses other) {
	// natural order is expiry time -
	// compare difference of expiry times rather than
	// expiry times directly, to avoid possible overflow.
	// (see System.nanoTime() recommendations...)
	long diff = this.expiryTime - other.expiryTime;
	if (diff < 0L) return -1;
	if (diff > 0L) return 1;
	// ties are broken using unique id
	return Long.compare(this.id, other.id);
	}
	}

	// a name service lookup based Addresses implementation which replaces itself
	// in cache when the result is obtained
	private static final class NameServiceAddresses implements Addresses {
	private final String host;
	private final InetAddress reqAddr;

	NameServiceAddresses(String host, InetAddress reqAddr) {
	this.host = host;
	this.reqAddr = reqAddr;
	}

	@Override
	public InetAddress[] get() throws UnknownHostException {
	Addresses addresses;
	// only one thread is doing lookup to name service
	// for particular host at any time.
	synchronized (this) {
	// re-check that we are still us + re-install us if slot empty
	addresses = cache.putIfAbsent(host, this);
	if (addresses == null) {
	// this can happen when we were replaced by CachedAddresses in
	// some other thread, then CachedAddresses expired and were
	// removed from cache while we were waiting for lock...
	addresses = this;
	}
	// still us ?
	if (addresses == this) {
	// lookup name services
	InetAddress[] inetAddresses;
	UnknownHostException ex;
	int cachePolicy;
	try {
	inetAddresses = getAddressesFromNameService(host, reqAddr);
	ex = null;
	cachePolicy = InetAddressCachePolicy.get();
	} catch (UnknownHostException uhe) {
	inetAddresses = null;
	ex = uhe;
	cachePolicy = InetAddressCachePolicy.getNegative();
	}
	// remove or replace us with cached addresses according to cachePolicy
	if (cachePolicy == InetAddressCachePolicy.NEVER) {
	cache.remove(host, this);
	} else {
	CachedAddresses cachedAddresses = new CachedAddresses(
	host,
	inetAddresses,
	cachePolicy == InetAddressCachePolicy.FOREVER
	? 0L
	// cachePolicy is in [s] - we need [ns]
	: System.nanoTime() + 1000_000_000L * cachePolicy
	);
	if (cache.replace(host, this, cachedAddresses) &&
	cachePolicy != InetAddressCachePolicy.FOREVER) {
	// schedule expiry
	expirySet.add(cachedAddresses);
	}
	}
	if (inetAddresses == null) {
	throw ex == null ? new UnknownHostException(host) : ex;
	}
	return inetAddresses;
	}
	// else addresses != this
	}
	// delegate to different addresses when we are already replaced
	// but outside of synchronized block to avoid any chance of dead-locking
	return addresses.get();
	}
	}

	/**
	* NameService provides host and address lookup service
	*
	* @since 9
	*/
	private interface NameService {

	/**
	* Lookup a host mapping by name. Retrieve the IP addresses
	* associated with a host
	*
	* @param host the specified hostname
	* @return array of IP addresses for the requested host
	* @throws UnknownHostException
	* if no IP address for the {@code host} could be found
	*/
	InetAddress[] lookupAllHostAddr(String host)
	throws UnknownHostException;

	/**
	* Lookup the host corresponding to the IP address provided
	*
	* @param addr byte array representing an IP address
	* @return {@code String} representing the host name mapping
	* @throws UnknownHostException
	* if no host found for the specified IP address
	*/
	String getHostByAddr(byte[] addr) throws UnknownHostException;

	}

	/**
	* The default NameService implementation, which delegates to the underlying
	* OS network libraries to resolve host address mappings.
	*
	* @since 9
	*/
	private static final class PlatformNameService implements NameService {

	public InetAddress[] lookupAllHostAddr(String host)
	throws UnknownHostException
	{
	return impl.lookupAllHostAddr(host);
	}

	public String getHostByAddr(byte[] addr)
	throws UnknownHostException
	{
	return impl.getHostByAddr(addr);
	}
	}

	/**
	* The HostsFileNameService provides host address mapping
	* by reading the entries in a hosts file, which is specified by
	* {@code jdk.net.hosts.file} system property
	*
	* <p>The file format is that which corresponds with the /etc/hosts file
	* IP Address host alias list.
	*
	* <p>When the file lookup is enabled it replaces the default NameService
	* implementation
	*
	* @since 9
	*/
	private static final class HostsFileNameService implements NameService {

	private static final InetAddress[] EMPTY_ARRAY = new InetAddress[0];

	// Specify if only IPv4 addresses should be returned by HostsFileService implementation
	private static final boolean preferIPv4Stack = Boolean.parseBoolean(
	GetPropertyAction.privilegedGetProperty("java.net.preferIPv4Stack"));

	private final String hostsFile;

	public HostsFileNameService(String hostsFileName) {
	this.hostsFile = hostsFileName;
	}

	/**
	* Lookup the host name corresponding to the IP address provided.
	* Search the configured host file a host name corresponding to
	* the specified IP address.
	*
	* @param addr byte array representing an IP address
	* @return {@code String} representing the host name mapping
	* @throws UnknownHostException
	* if no host found for the specified IP address
	*/
	@Override
	public String getHostByAddr(byte[] addr) throws UnknownHostException {
	String hostEntry;
	String host = null;

	try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
	UTF_8.INSTANCE))
	{
	while (hostsFileScanner.hasNextLine()) {
	hostEntry = hostsFileScanner.nextLine();
	if (!hostEntry.startsWith("#")) {
	hostEntry = removeComments(hostEntry);
	String[] mapping = hostEntry.split("\\s+");
	if (mapping.length >= 2 &&
	Arrays.equals(addr, createAddressByteArray(mapping[0]))) {
	host = mapping[1];
	break;
	}
	}
	}
	} catch (IOException e) {
	throw new UnknownHostException("Unable to resolve address "
	+ Arrays.toString(addr) + " as hosts file " + hostsFile
	+ " not found ");
	}

	if ((host == null) \|\| (host.isEmpty()) \|\| (host.equals(" "))) {
	throw new UnknownHostException("Requested address "
	+ Arrays.toString(addr)
	+ " resolves to an invalid entry in hosts file "
	+ hostsFile);
	}
	return host;
	}

	/**
	* <p>Lookup a host mapping by name. Retrieve the IP addresses
	* associated with a host.
	*
	* <p>Search the configured hosts file for the addresses associated
	* with the specified host name.
	*
	* @param host the specified hostname
	* @return array of IP addresses for the requested host
	* @throws UnknownHostException
	* if no IP address for the {@code host} could be found
	*/
	public InetAddress[] lookupAllHostAddr(String host)
	throws UnknownHostException {
	String hostEntry;
	String addrStr;
	byte addr[];
	List<InetAddress> inetAddresses = new ArrayList<>();
	List<InetAddress> inet4Addresses = new ArrayList<>();
	List<InetAddress> inet6Addresses = new ArrayList<>();

	// lookup the file and create a list InetAddress for the specified host
	try (Scanner hostsFileScanner = new Scanner(new File(hostsFile),
	UTF_8.INSTANCE)) {
	while (hostsFileScanner.hasNextLine()) {
	hostEntry = hostsFileScanner.nextLine();
	if (!hostEntry.startsWith("#")) {
	hostEntry = removeComments(hostEntry);
	if (hostEntry.contains(host)) {
	addrStr = extractHostAddr(hostEntry, host);
	if ((addrStr != null) && (!addrStr.isEmpty())) {
	addr = createAddressByteArray(addrStr);
	if (addr != null) {
	InetAddress address = InetAddress.getByAddress(host, addr);
	inetAddresses.add(address);
	if (address instanceof Inet4Address) {
	inet4Addresses.add(address);
	}
	if (address instanceof Inet6Address) {
	inet6Addresses.add(address);
	}
	}
	}
	}
	}
	}
	} catch (IOException e) {
	throw new UnknownHostException("Unable to resolve host " + host
	+ " as hosts file " + hostsFile + " not found ");
	}

	List<InetAddress> res;
	// If "preferIPv4Stack" system property is set to "true" then return
	// only IPv4 addresses
	if (preferIPv4Stack) {
	res = inet4Addresses;
	} else {
	// Otherwise, analyse "preferIPv6Addresses" value
	res = switch (preferIPv6Address) {
	case PREFER_IPV4_VALUE -> concatAddresses(inet4Addresses, inet6Addresses);
	case PREFER_IPV6_VALUE -> concatAddresses(inet6Addresses, inet4Addresses);
	default -> inetAddresses;
	};
	}

	if (res.isEmpty()) {
	throw new UnknownHostException("Unable to resolve host " + host
	+ " in hosts file " + hostsFile);
	}
	return res.toArray(EMPTY_ARRAY);
	}

	private static List<InetAddress> concatAddresses(List<InetAddress> firstPart,
	List<InetAddress> secondPart) {
	List<InetAddress> result = new ArrayList<>(firstPart);
	result.addAll(secondPart);
	return result;
	}

	private String removeComments(String hostsEntry) {
	String filteredEntry = hostsEntry;
	int hashIndex;

	if ((hashIndex = hostsEntry.indexOf("#")) != -1) {
	filteredEntry = hostsEntry.substring(0, hashIndex);
	}
	return filteredEntry;
	}

	private byte [] createAddressByteArray(String addrStr) {
	byte[] addrArray;
	// check if IPV4 address - most likely
	addrArray = IPAddressUtil.textToNumericFormatV4(addrStr);
	if (addrArray == null) {
	addrArray = IPAddressUtil.textToNumericFormatV6(addrStr);
	}
	return addrArray;
	}

	/** host to ip address mapping */
	private String extractHostAddr(String hostEntry, String host) {
	String[] mapping = hostEntry.split("\\s+");
	String hostAddr = null;

	if (mapping.length >= 2) {
	// look at the host aliases
	for (int i = 1; i < mapping.length; i++) {
	if (mapping[i].equalsIgnoreCase(host)) {
	hostAddr = mapping[0];
	}
	}
	}
	return hostAddr;
	}
	}

	static final InetAddressImpl impl;

	static {
	// create the impl
	impl = InetAddressImplFactory.create();

	// create name service
	nameService = createNameService();
	}

	/**
	* Create an instance of the NameService interface based on
	* the setting of the {@code jdk.net.hosts.file} system property.
	*
	* <p>The default NameService is the PlatformNameService, which typically
	* delegates name and address resolution calls to the underlying
	* OS network libraries.
	*
	* <p> A HostsFileNameService is created if the {@code jdk.net.hosts.file}
	* system property is set. If the specified file doesn't exist, the name or
	* address lookup will result in an UnknownHostException. Thus, non existent
	* hosts file is handled as if the file is empty.
	*
	* @return a NameService
	*/
	private static NameService createNameService() {

	String hostsFileName =
	GetPropertyAction.privilegedGetProperty("jdk.net.hosts.file");
	NameService theNameService;
	if (hostsFileName != null) {
	theNameService = new HostsFileNameService(hostsFileName);
	} else {
	theNameService = new PlatformNameService();
	}
	return theNameService;
	}

	/**
	* Creates an InetAddress based on the provided host name and IP address.
	* No name service is checked for the validity of the address.
	*
	* <p> The host name can either be a machine name, such as
	* "{@code www.example.com}", or a textual representation of its IP
	* address.
	* <p> No validity checking is done on the host name either.
	*
	* <p> If addr specifies an IPv4 address an instance of Inet4Address
	* will be returned; otherwise, an instance of Inet6Address
	* will be returned.
	*
	* <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
	* must be 16 bytes long
	*
	* @param host the specified host
	* @param addr the raw IP address in network byte order
	* @return an InetAddress object created from the raw IP address.
	* @throws UnknownHostException if IP address is of illegal length
	* @since 1.4
	*/
	public static InetAddress getByAddress(String host, byte[] addr)
	throws UnknownHostException {
	if (host != null && !host.isEmpty() && host.charAt(0) == '[') {
	if (host.charAt(host.length()-1) == ']') {
	host = host.substring(1, host.length() -1);
	}
	}
	if (addr != null) {
	if (addr.length == Inet4Address.INADDRSZ) {
	return new Inet4Address(host, addr);
	} else if (addr.length == Inet6Address.INADDRSZ) {
	byte[] newAddr
	= IPAddressUtil.convertFromIPv4MappedAddress(addr);
	if (newAddr != null) {
	return new Inet4Address(host, newAddr);
	} else {
	return new Inet6Address(host, addr);
	}
	}
	}
	throw new UnknownHostException("addr is of illegal length");
	}


	/**
	* Determines the IP address of a host, given the host's name.
	*
	* <p> The host name can either be a machine name, such as
	* "{@code www.example.com}", or a textual representation of its
	* IP address. If a literal IP address is supplied, only the
	* validity of the address format is checked.
	*
	* <p> For {@code host} specified in literal IPv6 address,
	* either the form defined in RFC 2732 or the literal IPv6 address
	* format defined in RFC 2373 is accepted. IPv6 scoped addresses are also
	* supported. See <a href="Inet6Address.html#scoped">here</a> for a description of IPv6
	* scoped addresses.
	*
	* <p> If the host is {@code null} or {@code host.length()} is equal
	* to zero, then an {@code InetAddress} representing an address of the
	* loopback interface is returned.
	* See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
	* section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
	* section 2.5.3.
	*
	* <p> If there is a security manager, and {@code host} is not {@code null}
	* or {@code host.length() } is not equal to zero, the security manager's
	* {@code checkConnect} method is called with the hostname and {@code -1}
	* as its arguments to determine if the operation is allowed.
	*
	* @param host the specified host, or {@code null}.
	* @return an IP address for the given host name.
	* @throws UnknownHostException if no IP address for the
	* {@code host} could be found, or if a scope_id was specified
	* for a global IPv6 address.
	* @throws SecurityException if a security manager exists
	* and its checkConnect method doesn't allow the operation
	*/
	public static InetAddress getByName(String host)
	throws UnknownHostException {
	return InetAddress.getAllByName(host)[0];
	}

	// called from deployment cache manager
	private static InetAddress getByName(String host, InetAddress reqAddr)
	throws UnknownHostException {
	return InetAddress.getAllByName(host, reqAddr)[0];
	}

	/**
	* Given the name of a host, returns an array of its IP addresses,
	* based on the configured name service on the system.
	*
	* <p> The host name can either be a machine name, such as
	* "{@code www.example.com}", or a textual representation of its IP
	* address. If a literal IP address is supplied, only the
	* validity of the address format is checked.
	*
	* <p> For {@code host} specified in <i>literal IPv6 address</i>,
	* either the form defined in RFC 2732 or the literal IPv6 address
	* format defined in RFC 2373 is accepted. A literal IPv6 address may
	* also be qualified by appending a scoped zone identifier or scope_id.
	* The syntax and usage of scope_ids is described
	* <a href="Inet6Address.html#scoped">here</a>.
	*
	* <p> If the host is {@code null} or {@code host.length()} is equal
	* to zero, then an {@code InetAddress} representing an address of the
	* loopback interface is returned.
	* See <a href="http://www.ietf.org/rfc/rfc3330.txt">RFC 3330</a>
	* section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>
	* section 2.5.3. </p>
	*
	* <p> If there is a security manager, and {@code host} is not {@code null}
	* or {@code host.length() } is not equal to zero, the security manager's
	* {@code checkConnect} method is called with the hostname and {@code -1}
	* as its arguments to determine if the operation is allowed.
	*
	* @param host the name of the host, or {@code null}.
	* @return an array of all the IP addresses for a given host name.
	*
	* @throws UnknownHostException if no IP address for the
	* {@code host} could be found, or if a scope_id was specified
	* for a global IPv6 address.
	* @throws SecurityException if a security manager exists and its
	* {@code checkConnect} method doesn't allow the operation.
	*
	* @see SecurityManager#checkConnect
	*/
	public static InetAddress[] getAllByName(String host)
	throws UnknownHostException {
	return getAllByName(host, null);
	}

	private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
	throws UnknownHostException {

	if (host == null \|\| host.isEmpty()) {
	InetAddress[] ret = new InetAddress[1];
	ret[0] = impl.loopbackAddress();
	return ret;
	}

	boolean ipv6Expected = false;
	if (host.charAt(0) == '[') {
	// This is supposed to be an IPv6 literal
	if (host.length() > 2 && host.charAt(host.length()-1) == ']') {
	host = host.substring(1, host.length() -1);
	ipv6Expected = true;
	} else {
	// This was supposed to be a IPv6 address, but it's not!
	throw new UnknownHostException(host + ": invalid IPv6 address");
	}
	}

	// if host is an IP address, we won't do further lookup
	if (Character.digit(host.charAt(0), 16) != -1
	\|\| (host.charAt(0) == ':')) {
	byte[] addr = null;
	int numericZone = -1;
	String ifname = null;
	// see if it is IPv4 address
	addr = IPAddressUtil.textToNumericFormatV4(host);
	if (addr == null) {
	// This is supposed to be an IPv6 literal
	// Check if a numeric or string zone id is present
	int pos;
	if ((pos=host.indexOf ('%')) != -1) {
	numericZone = checkNumericZone (host);
	if (numericZone == -1) { /* remainder of string must be an ifname */
	ifname = host.substring (pos+1);
	}
	}
	if ((addr = IPAddressUtil.textToNumericFormatV6(host)) == null && host.contains(":")) {
	throw new UnknownHostException(host + ": invalid IPv6 address");
	}
	} else if (ipv6Expected) {
	// Means an IPv4 literal between brackets!
	throw new UnknownHostException("["+host+"]");
	}
	InetAddress[] ret = new InetAddress[1];
	if(addr != null) {
	if (addr.length == Inet4Address.INADDRSZ) {
	ret[0] = new Inet4Address(null, addr);
	} else {
	if (ifname != null) {
	ret[0] = new Inet6Address(null, addr, ifname);
	} else {
	ret[0] = new Inet6Address(null, addr, numericZone);
	}
	}
	return ret;
	}
	} else if (ipv6Expected) {
	// We were expecting an IPv6 Literal, but got something else
	throw new UnknownHostException("["+host+"]");
	}
	return getAllByName0(host, reqAddr, true, true);
	}

	/**
	* Returns the loopback address.
	* <p>
	* The InetAddress returned will represent the IPv4
	* loopback address, 127.0.0.1, or the IPv6 loopback
	* address, ::1. The IPv4 loopback address returned
	* is only one of many in the form 127...*
	*
	* @return the InetAddress loopback instance.
	* @since 1.7
	*/
	public static InetAddress getLoopbackAddress() {
	return impl.loopbackAddress();
	}


	/**
	* check if the literal address string has %nn appended
	* returns -1 if not, or the numeric value otherwise.
	*
	* %nn may also be a string that represents the displayName of
	* a currently available NetworkInterface.
	*/
	private static int checkNumericZone (String s) throws UnknownHostException {
	int percent = s.indexOf ('%');
	int slen = s.length();
	int digit, zone=0;
	if (percent == -1) {
	return -1;
	}
	for (int i=percent+1; i<slen; i++) {
	char c = s.charAt(i);
	if (c == ']') {
	if (i == percent+1) {
	/* empty per-cent field */
	return -1;
	}
	break;
	}
	if ((digit = Character.digit (c, 10)) < 0) {
	return -1;
	}
	zone = (zone * 10) + digit;
	}
	return zone;
	}

	private static InetAddress[] getAllByName0 (String host)
	throws UnknownHostException
	{
	return getAllByName0(host, true);
	}

	/**
	* package private so SocketPermission can call it
	*/
	static InetAddress[] getAllByName0 (String host, boolean check)
	throws UnknownHostException {
	return getAllByName0 (host, null, check, true);
	}

	/**
	* Designated lookup method.
	*
	* @param host host name to look up
	* @param reqAddr requested address to be the 1st in returned array
	* @param check perform security check
	* @param useCache use cached value if not expired else always
	* perform name service lookup (and cache the result)
	* @return array of InetAddress(es)
	* @throws UnknownHostException if host name is not found
	*/
	private static InetAddress[] getAllByName0(String host,
	InetAddress reqAddr,
	boolean check,
	boolean useCache)
	throws UnknownHostException {

	/* If it gets here it is presumed to be a hostname */

	/* make sure the connection to the host is allowed, before we
	* give out a hostname
	*/
	if (check) {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkConnect(host, -1);
	}
	}

	// remove expired addresses from cache - expirySet keeps them ordered
	// by expiry time so we only need to iterate the prefix of the NavigableSet...
	long now = System.nanoTime();
	for (CachedAddresses caddrs : expirySet) {
	// compare difference of time instants rather than
	// time instants directly, to avoid possible overflow.
	// (see System.nanoTime() recommendations...)
	if ((caddrs.expiryTime - now) < 0L) {
	// ConcurrentSkipListSet uses weakly consistent iterator,
	// so removing while iterating is OK...
	if (expirySet.remove(caddrs)) {
	// ... remove from cache
	cache.remove(caddrs.host, caddrs);
	}
	} else {
	// we encountered 1st element that expires in future
	break;
	}
	}

	// look-up or remove from cache
	Addresses addrs;
	if (useCache) {
	addrs = cache.get(host);
	} else {
	addrs = cache.remove(host);
	if (addrs != null) {
	if (addrs instanceof CachedAddresses) {
	// try removing from expirySet too if CachedAddresses
	expirySet.remove(addrs);
	}
	addrs = null;
	}
	}

	if (addrs == null) {
	// create a NameServiceAddresses instance which will look up
	// the name service and install it within cache...
	Addresses oldAddrs = cache.putIfAbsent(
	host,
	addrs = new NameServiceAddresses(host, reqAddr)
	);
	if (oldAddrs != null) { // lost putIfAbsent race
	addrs = oldAddrs;
	}
	}

	// ask Addresses to get an array of InetAddress(es) and clone it
	return addrs.get().clone();
	}

	static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
	throws UnknownHostException
	{
	InetAddress[] addresses = null;
	UnknownHostException ex = null;

	try {
	addresses = nameService.lookupAllHostAddr(host);
	} catch (UnknownHostException uhe) {
	if (host.equalsIgnoreCase("localhost")) {
	addresses = new InetAddress[] { impl.loopbackAddress() };
	}
	else {
	ex = uhe;
	}
	}

	if (addresses == null) {
	throw ex == null ? new UnknownHostException(host) : ex;
	}

	// More to do?
	if (reqAddr != null && addresses.length > 1 && !addresses[0].equals(reqAddr)) {
	// Find it?
	int i = 1;
	for (; i < addresses.length; i++) {
	if (addresses[i].equals(reqAddr)) {
	break;
	}
	}
	// Rotate
	if (i < addresses.length) {
	InetAddress tmp, tmp2 = reqAddr;
	for (int j = 0; j < i; j++) {
	tmp = addresses[j];
	addresses[j] = tmp2;
	tmp2 = tmp;
	}
	addresses[i] = tmp2;
	}
	}

	return addresses;
	}

	/**
	* Returns an {@code InetAddress} object given the raw IP address .
	* The argument is in network byte order: the highest order
	* byte of the address is in {@code getAddress()[0]}.
	*
	* <p> This method doesn't block, i.e. no reverse name service lookup
	* is performed.
	*
	* <p> IPv4 address byte array must be 4 bytes long and IPv6 byte array
	* must be 16 bytes long
	*
	* @param addr the raw IP address in network byte order
	* @return an InetAddress object created from the raw IP address.
	* @throws UnknownHostException if IP address is of illegal length
	* @since 1.4
	*/
	public static InetAddress getByAddress(byte[] addr)
	throws UnknownHostException {
	return getByAddress(null, addr);
	}

	private static final class CachedLocalHost {
	final String host;
	final InetAddress addr;
	final long expiryTime = System.nanoTime() + 5000_000_000L; // now + 5s;

	CachedLocalHost(String host, InetAddress addr) {
	this.host = host;
	this.addr = addr;
	}
	}

	private static volatile CachedLocalHost cachedLocalHost;

	/**
	* Returns the address of the local host. This is achieved by retrieving
	* the name of the host from the system, then resolving that name into
	* an {@code InetAddress}.
	*
	* <P>Note: The resolved address may be cached for a short period of time.
	* </P>
	*
	* <p>If there is a security manager, its
	* {@code checkConnect} method is called
	* with the local host name and {@code -1}
	* as its arguments to see if the operation is allowed.
	* If the operation is not allowed, an InetAddress representing
	* the loopback address is returned.
	*
	* @return the address of the local host.
	*
	* @throws UnknownHostException if the local host name could not
	* be resolved into an address.
	*
	* @see SecurityManager#checkConnect
	* @see java.net.InetAddress#getByName(java.lang.String)
	*/
	public static InetAddress getLocalHost() throws UnknownHostException {

	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	try {
	// is cached data still valid?
	CachedLocalHost clh = cachedLocalHost;
	if (clh != null && (clh.expiryTime - System.nanoTime()) >= 0L) {
	if (security != null) {
	security.checkConnect(clh.host, -1);
	}
	return clh.addr;
	}

	String local = impl.getLocalHostName();

	if (security != null) {
	security.checkConnect(local, -1);
	}

	InetAddress localAddr;
	if (local.equals("localhost")) {
	// shortcut for "localhost" host name
	localAddr = impl.loopbackAddress();
	} else {
	// call getAllByName0 without security checks and
	// without using cached data
	try {
	localAddr = getAllByName0(local, null, false, false)[0];
	} catch (UnknownHostException uhe) {
	// Rethrow with a more informative error message.
	UnknownHostException uhe2 =
	new UnknownHostException(local + ": " +
	uhe.getMessage());
	uhe2.initCause(uhe);
	throw uhe2;
	}
	}
	cachedLocalHost = new CachedLocalHost(local, localAddr);
	return localAddr;
	} catch (java.lang.SecurityException e) {
	return impl.loopbackAddress();
	}
	}

	/**
	* Perform class load-time initializations.
	*/
	private static native void init();


	/*
	* Returns the InetAddress representing anyLocalAddress
	* (typically 0.0.0.0 or ::0)
	*/
	static InetAddress anyLocalAddress() {
	return impl.anyLocalAddress();
	}

	/*
	* Load and instantiate an underlying impl class
	*/
	static InetAddressImpl loadImpl(String implName) {
	Object impl = null;

	/*
	* Property "impl.prefix" will be prepended to the classname
	* of the implementation object we instantiate, to which we
	* delegate the real work (like native methods). This
	* property can vary across implementations of the java.
	* classes. The default is an empty String "".
	*/
	String prefix = GetPropertyAction.privilegedGetProperty("impl.prefix", "");
	try {
	@SuppressWarnings("deprecation")
	Object tmp = Class.forName("java.net." + prefix + implName).newInstance();
	impl = tmp;
	} catch (ClassNotFoundException e) {
	System.err.println("Class not found: java.net." + prefix +
	implName + ":\ncheck impl.prefix property " +
	"in your properties file.");
	} catch (InstantiationException e) {
	System.err.println("Could not instantiate: java.net." + prefix +
	implName + ":\ncheck impl.prefix property " +
	"in your properties file.");
	} catch (IllegalAccessException e) {
	System.err.println("Cannot access class: java.net." + prefix +
	implName + ":\ncheck impl.prefix property " +
	"in your properties file.");
	}

	if (impl == null) {
	try {
	@SuppressWarnings("deprecation")
	Object tmp = Class.forName(implName).newInstance();
	impl = tmp;
	} catch (Exception e) {
	throw new Error("System property impl.prefix incorrect");
	}
	}

	return (InetAddressImpl) impl;
	}

	/**
	* Initializes an empty InetAddress.
	*/
	@java.io.Serial
	private void readObjectNoData () {
	if (getClass().getClassLoader() != null) {
	throw new SecurityException ("invalid address type");
	}
	}

	private static final jdk.internal.misc.Unsafe UNSAFE
	= jdk.internal.misc.Unsafe.getUnsafe();
	private static final long FIELDS_OFFSET
	= UNSAFE.objectFieldOffset(InetAddress.class, "holder");

	/**
	* Restores the state of this object from the stream.
	*
	* @param s the {@code ObjectInputStream} from which data is read
	* @throws IOException if an I/O error occurs
	* @throws ClassNotFoundException if a serialized class cannot be loaded
	*/
	@java.io.Serial
	private void readObject (ObjectInputStream s) throws
	IOException, ClassNotFoundException {
	if (getClass().getClassLoader() != null) {
	throw new SecurityException ("invalid address type");
	}
	GetField gf = s.readFields();
	String host = (String)gf.get("hostName", null);
	int address = gf.get("address", 0);
	int family = gf.get("family", 0);
	if (family != IPv4 && family != IPv6) {
	throw new InvalidObjectException("invalid address family type: " + family);
	}
	InetAddressHolder h = new InetAddressHolder(host, address, family);
	UNSAFE.putReference(this, FIELDS_OFFSET, h);
	}

	/* needed because the serializable fields no longer exist */

	/**
	* @serialField hostName String the hostname for this address
	* @serialField address int holds a 32-bit IPv4 address.
	* @serialField family int specifies the address family type, for instance,
	* {@code '1'} for IPv4 addresses, and {@code '2'} for IPv6 addresses.
	*/
	@java.io.Serial
	private static final ObjectStreamField[] serialPersistentFields = {
	new ObjectStreamField("hostName", String.class),
	new ObjectStreamField("address", int.class),
	new ObjectStreamField("family", int.class),
	};

	/**
	* Writes the state of this object to the stream.
	*
	* @param s the {@code ObjectOutputStream} to which data is written
	* @throws IOException if an I/O error occurs
	*/
	@java.io.Serial
	private void writeObject (ObjectOutputStream s) throws
	IOException {
	if (getClass().getClassLoader() != null) {
	throw new SecurityException ("invalid address type");
	}
	PutField pf = s.putFields();
	pf.put("hostName", holder().getHostName());
	pf.put("address", holder().getAddress());
	pf.put("family", holder().getFamily());
	s.writeFields();
	}
	}

	/*
	* Simple factory to create the impl
	*/
	class InetAddressImplFactory {

	static InetAddressImpl create() {
	return InetAddress.loadImpl(isIPv6Supported() ?
	"Inet6AddressImpl" : "Inet4AddressImpl");
	}

	static native boolean isIPv6Supported();
	}

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