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Java example source code file (InetAddress.java)
This example Java source code file (InetAddress.java) is included in the alvinalexander.com
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The InetAddress.java Java example source code
/*
* Copyright (c) 1995, 2013, 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.HashMap;
import java.util.LinkedHashMap;
import java.util.Random;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ArrayList;
import java.util.ServiceLoader;
import java.security.AccessController;
import java.io.ObjectStreamException;
import java.io.ObjectStreamField;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectInputStream.GetField;
import java.io.ObjectOutputStream;
import java.io.ObjectOutputStream.PutField;
import sun.security.action.*;
import sun.net.InetAddressCachePolicy;
import sun.net.util.IPAddressUtil;
import sun.net.spi.nameservice.*;
/**
* 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>, RFC 1918:
* Address Allocation for Private Internets</i>, RFC 2365:
* Administratively Scoped IP Multicast</i>, and RFC 2373: IP
* Version 6 Addressing Architecture</i>. 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).
*
* <h3> Address types
*
* <blockquote>
* <tr>
* <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 unspecified address must not be used as
* the destination address of an IP packet.
*
* <p> The Loopback 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>
* <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>
* </table>
*
* <h4> IP address scope
*
* <p> Link-local 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> Site-local addresses are designed to be used for addressing
* inside of a site without the need for a global prefix.
*
* <p> Global addresses are unique across the internet.
*
* <h4> Textual representation of IP addresses
*
* 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 couple of
* System Properties</a> affecting how IPv4 and IPv6 addresses are used.
*
* <h4> Host Name Resolution
*
* Host name-to-IP address <i>resolution 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> Reverse name resolution 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.
*
* <h4> InetAddress Caching
*
* 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:
*
* <blockquote>
* <dl>
* <dt>networkaddress.cache.ttl
* <dd>Indicates the caching policy for successful name lookups from
* the name service. The value is specified as as 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>networkaddress.cache.negative.ttl (default: 10)
* <dd>Indicates the caching policy for un-successful name lookups
* from the name service. The value is specified as as 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>
* </blockquote>
*
* @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 JDK1.0
*/
public
class InetAddress implements java.io.Serializable {
/**
* Specify the address family: Internet Protocol, Version 4
* @since 1.4
*/
static final int IPv4 = 1;
/**
* Specify the address family: Internet Protocol, Version 6
* @since 1.4
*/
static final int IPv6 = 2;
/* Specify address family preference */
static transient boolean preferIPv6Address = false;
static class InetAddressHolder {
InetAddressHolder() {}
InetAddressHolder(String hostName, int address, int family) {
this.hostName = hostName;
this.address = address;
this.family = family;
}
void init(String hostName, int family) {
this.hostName = hostName;
if (family != -1) {
this.family = family;
}
}
String hostName;
String getHostName() {
return hostName;
}
/**
* 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 List<NameService> nameServices = null;
/* Used to store the best available hostname */
private transient String canonicalHostName = null;
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = 3286316764910316507L;
/*
* Load net library into runtime, and perform initializations.
*/
static {
preferIPv6Address = java.security.AccessController.doPrivileged(
new GetBooleanAction("java.net.preferIPv6Addresses")).booleanValue();
AccessController.doPrivileged(
new java.security.PrivilegedAction<Void>() {
public Void run() {
System.loadLibrary("net");
return null;
}
});
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
*/
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 JDK1.1
*/
public boolean isMulticastAddress() {
return false;
}
/**
* 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
*/
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() {
if (canonicalHostName == null) {
canonicalHostName =
InetAddress.getHostFromNameService(this, true);
}
return canonicalHostName;
}
/**
* 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;
for (NameService nameService : nameServices) {
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) {
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;
}
break;
} catch (SecurityException e) {
host = addr.getHostAddress();
break;
} 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 JDK1.0.2
*/
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 ((hostName != null) ? hostName : "")
+ "/" + getHostAddress();
}
/*
* Cached addresses - our own litle nis, not!
*/
private static Cache addressCache = new Cache(Cache.Type.Positive);
private static Cache negativeCache = new Cache(Cache.Type.Negative);
private static boolean addressCacheInit = false;
static InetAddress[] unknown_array; // put THIS in cache
static InetAddressImpl impl;
private static final HashMap<String, Void> lookupTable = new HashMap<>();
/**
* Represents a cache entry
*/
static final class CacheEntry {
CacheEntry(InetAddress[] addresses, long expiration) {
this.addresses = addresses;
this.expiration = expiration;
}
InetAddress[] addresses;
long expiration;
}
/**
* A cache that manages entries based on a policy specified
* at creation time.
*/
static final class Cache {
private LinkedHashMap<String, CacheEntry> cache;
private Type type;
enum Type {Positive, Negative};
/**
* Create cache
*/
public Cache(Type type) {
this.type = type;
cache = new LinkedHashMap<String, CacheEntry>();
}
private int getPolicy() {
if (type == Type.Positive) {
return InetAddressCachePolicy.get();
} else {
return InetAddressCachePolicy.getNegative();
}
}
/**
* Add an entry to the cache. If there's already an
* entry then for this host then the entry will be
* replaced.
*/
public Cache put(String host, InetAddress[] addresses) {
int policy = getPolicy();
if (policy == InetAddressCachePolicy.NEVER) {
return this;
}
// purge any expired entries
if (policy != InetAddressCachePolicy.FOREVER) {
// As we iterate in insertion order we can
// terminate when a non-expired entry is found.
LinkedList<String> expired = new LinkedList<>();
long now = System.currentTimeMillis();
for (String key : cache.keySet()) {
CacheEntry entry = cache.get(key);
if (entry.expiration >= 0 && entry.expiration < now) {
expired.add(key);
} else {
break;
}
}
for (String key : expired) {
cache.remove(key);
}
}
// create new entry and add it to the cache
// -- as a HashMap replaces existing entries we
// don't need to explicitly check if there is
// already an entry for this host.
long expiration;
if (policy == InetAddressCachePolicy.FOREVER) {
expiration = -1;
} else {
expiration = System.currentTimeMillis() + (policy * 1000);
}
CacheEntry entry = new CacheEntry(addresses, expiration);
cache.put(host, entry);
return this;
}
/**
* Query the cache for the specific host. If found then
* return its CacheEntry, or null if not found.
*/
public CacheEntry get(String host) {
int policy = getPolicy();
if (policy == InetAddressCachePolicy.NEVER) {
return null;
}
CacheEntry entry = cache.get(host);
// check if entry has expired
if (entry != null && policy != InetAddressCachePolicy.FOREVER) {
if (entry.expiration >= 0 &&
entry.expiration < System.currentTimeMillis()) {
cache.remove(host);
entry = null;
}
}
return entry;
}
}
/*
* Initialize cache and insert anyLocalAddress into the
* unknown array with no expiry.
*/
private static void cacheInitIfNeeded() {
assert Thread.holdsLock(addressCache);
if (addressCacheInit) {
return;
}
unknown_array = new InetAddress[1];
unknown_array[0] = impl.anyLocalAddress();
addressCache.put(impl.anyLocalAddress().getHostName(),
unknown_array);
addressCacheInit = true;
}
/*
* Cache the given hostname and addresses.
*/
private static void cacheAddresses(String hostname,
InetAddress[] addresses,
boolean success) {
hostname = hostname.toLowerCase();
synchronized (addressCache) {
cacheInitIfNeeded();
if (success) {
addressCache.put(hostname, addresses);
} else {
negativeCache.put(hostname, addresses);
}
}
}
/*
* Lookup hostname in cache (positive & negative cache). If
* found return addresses, null if not found.
*/
private static InetAddress[] getCachedAddresses(String hostname) {
hostname = hostname.toLowerCase();
// search both positive & negative caches
synchronized (addressCache) {
cacheInitIfNeeded();
CacheEntry entry = addressCache.get(hostname);
if (entry == null) {
entry = negativeCache.get(hostname);
}
if (entry != null) {
return entry.addresses;
}
}
// not found
return null;
}
private static NameService createNSProvider(String provider) {
if (provider == null)
return null;
NameService nameService = null;
if (provider.equals("default")) {
// initialize the default name service
nameService = new NameService() {
public InetAddress[] lookupAllHostAddr(String host)
throws UnknownHostException {
return impl.lookupAllHostAddr(host);
}
public String getHostByAddr(byte[] addr)
throws UnknownHostException {
return impl.getHostByAddr(addr);
}
};
} else {
final String providerName = provider;
try {
nameService = java.security.AccessController.doPrivileged(
new java.security.PrivilegedExceptionAction<NameService>() {
public NameService run() {
Iterator<NameServiceDescriptor> itr =
ServiceLoader.load(NameServiceDescriptor.class)
.iterator();
while (itr.hasNext()) {
NameServiceDescriptor nsd = itr.next();
if (providerName.
equalsIgnoreCase(nsd.getType()+","
+nsd.getProviderName())) {
try {
return nsd.createNameService();
} catch (Exception e) {
e.printStackTrace();
System.err.println(
"Cannot create name service:"
+providerName+": " + e);
}
}
}
return null;
}
}
);
} catch (java.security.PrivilegedActionException e) {
}
}
return nameService;
}
static {
// create the impl
impl = InetAddressImplFactory.create();
// get name service if provided and requested
String provider = null;;
String propPrefix = "sun.net.spi.nameservice.provider.";
int n = 1;
nameServices = new ArrayList<NameService>();
provider = AccessController.doPrivileged(
new GetPropertyAction(propPrefix + n));
while (provider != null) {
NameService ns = createNSProvider(provider);
if (ns != null)
nameServices.add(ns);
n++;
provider = AccessController.doPrivileged(
new GetPropertyAction(propPrefix + n));
}
// if not designate any name services provider,
// create a default one
if (nameServices.size() == 0) {
NameService ns = createNSProvider("default");
nameServices.add(ns);
}
}
/**
* 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 java.sun.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.
* @exception 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.length() > 0 && 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 java.sun.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 for a description of IPv6
* scoped addresses.
*
* <p> If the host is {@code null} 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
* section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373
* section 2.5.3. </p>
*
* @param host the specified host, or {@code null}.
* @return an IP address for the given host name.
* @exception UnknownHostException if no IP address for the
* {@code host} could be found, or if a scope_id was specified
* for a global IPv6 address.
* @exception 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 java.sun.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. 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.
* <p> If the host is {@code null} 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
* section 2 and <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373
* section 2.5.3. </p>
*
* <p> If there is a security manager and {@code host} is not
* null and {@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 see 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.
*
* @exception UnknownHostException if no IP address for the
* {@code host} could be found, or if a scope_id was specified
* for a global IPv6 address.
* @exception 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.length() == 0) {
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 litteral 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 Litteral, but got something else
throw new UnknownHostException("["+host+"]");
}
return getAllByName0(host, reqAddr, 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);
}
private static InetAddress[] getAllByName0 (String host, InetAddress reqAddr, boolean check)
throws UnknownHostException {
/* If it gets here it is presumed to be a hostname */
/* Cache.get can return: null, unknownAddress, or InetAddress[] */
/* make sure the connection to the host is allowed, before we
* give out a hostname
*/
if (check) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkConnect(host, -1);
}
}
InetAddress[] addresses = getCachedAddresses(host);
/* If no entry in cache, then do the host lookup */
if (addresses == null) {
addresses = getAddressesFromNameService(host, reqAddr);
}
if (addresses == unknown_array)
throw new UnknownHostException(host);
return addresses.clone();
}
private static InetAddress[] getAddressesFromNameService(String host, InetAddress reqAddr)
throws UnknownHostException
{
InetAddress[] addresses = null;
boolean success = false;
UnknownHostException ex = null;
// Check whether the host is in the lookupTable.
// 1) If the host isn't in the lookupTable when
// checkLookupTable() is called, checkLookupTable()
// would add the host in the lookupTable and
// return null. So we will do the lookup.
// 2) If the host is in the lookupTable when
// checkLookupTable() is called, the current thread
// would be blocked until the host is removed
// from the lookupTable. Then this thread
// should try to look up the addressCache.
// i) if it found the addresses in the
// addressCache, checkLookupTable() would
// return the addresses.
// ii) if it didn't find the addresses in the
// addressCache for any reason,
// it should add the host in the
// lookupTable and return null so the
// following code would do a lookup itself.
if ((addresses = checkLookupTable(host)) == null) {
try {
// This is the first thread which looks up the addresses
// this host or the cache entry for this host has been
// expired so this thread should do the lookup.
for (NameService nameService : nameServices) {
try {
/*
* Do not put the call to lookup() inside the
* constructor. if you do you will still be
* allocating space when the lookup fails.
*/
addresses = nameService.lookupAllHostAddr(host);
success = true;
break;
} catch (UnknownHostException uhe) {
if (host.equalsIgnoreCase("localhost")) {
InetAddress[] local = new InetAddress[] { impl.loopbackAddress() };
addresses = local;
success = true;
break;
}
else {
addresses = unknown_array;
success = false;
ex = uhe;
}
}
}
// 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;
}
}
// Cache the address.
cacheAddresses(host, addresses, success);
if (!success && ex != null)
throw ex;
} finally {
// Delete host from the lookupTable and notify
// all threads waiting on the lookupTable monitor.
updateLookupTable(host);
}
}
return addresses;
}
private static InetAddress[] checkLookupTable(String host) {
synchronized (lookupTable) {
// If the host isn't in the lookupTable, add it in the
// lookuptable and return null. The caller should do
// the lookup.
if (lookupTable.containsKey(host) == false) {
lookupTable.put(host, null);
return null;
}
// If the host is in the lookupTable, it means that another
// thread is trying to look up the addresses of this host.
// This thread should wait.
while (lookupTable.containsKey(host)) {
try {
lookupTable.wait();
} catch (InterruptedException e) {
}
}
}
// The other thread has finished looking up the addresses of
// the host. This thread should retry to get the addresses
// from the addressCache. If it doesn't get the addresses from
// the cache, it will try to look up the addresses itself.
InetAddress[] addresses = getCachedAddresses(host);
if (addresses == null) {
synchronized (lookupTable) {
lookupTable.put(host, null);
return null;
}
}
return addresses;
}
private static void updateLookupTable(String host) {
synchronized (lookupTable) {
lookupTable.remove(host);
lookupTable.notifyAll();
}
}
/**
* 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.
* @exception 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 InetAddress cachedLocalHost = null;
private static long cacheTime = 0;
private static final long maxCacheTime = 5000L;
private static final Object cacheLock = new Object();
/**
* 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.
*
* @exception 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 {
SecurityManager security = System.getSecurityManager();
try {
String local = impl.getLocalHostName();
if (security != null) {
security.checkConnect(local, -1);
}
if (local.equals("localhost")) {
return impl.loopbackAddress();
}
InetAddress ret = null;
synchronized (cacheLock) {
long now = System.currentTimeMillis();
if (cachedLocalHost != null) {
if ((now - cacheTime) < maxCacheTime) // Less than 5s old?
ret = cachedLocalHost;
else
cachedLocalHost = null;
}
// we are calling getAddressesFromNameService directly
// to avoid getting localHost from cache
if (ret == null) {
InetAddress[] localAddrs;
try {
localAddrs =
InetAddress.getAddressesFromNameService(local, null);
} catch (UnknownHostException uhe) {
// Rethrow with a more informative error message.
UnknownHostException uhe2 =
new UnknownHostException(local + ": " +
uhe.getMessage());
uhe2.initCause(uhe);
throw uhe2;
}
cachedLocalHost = localAddrs[0];
cacheTime = now;
ret = localAddrs[0];
}
}
return ret;
} 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 = AccessController.doPrivileged(
new GetPropertyAction("impl.prefix", ""));
try {
impl = Class.forName("java.net." + prefix + implName).newInstance();
} 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 {
impl = Class.forName(implName).newInstance();
} catch (Exception e) {
throw new Error("System property impl.prefix incorrect");
}
}
return (InetAddressImpl) impl;
}
private void readObjectNoData (ObjectInputStream s) throws
IOException, ClassNotFoundException {
if (getClass().getClassLoader() != null) {
throw new SecurityException ("invalid address type");
}
}
private static final long FIELDS_OFFSET;
private static final sun.misc.Unsafe UNSAFE;
static {
try {
sun.misc.Unsafe unsafe = sun.misc.Unsafe.getUnsafe();
FIELDS_OFFSET = unsafe.objectFieldOffset(
InetAddress.class.getDeclaredField("holder")
);
UNSAFE = unsafe;
} catch (ReflectiveOperationException e) {
throw new Error(e);
}
}
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);
InetAddressHolder h = new InetAddressHolder(host, address, family);
UNSAFE.putObject(this, FIELDS_OFFSET, h);
}
/* needed because the serializable fields no longer exist */
/**
* @serialField hostName String
* @serialField address int
* @serialField family int
*/
private static final ObjectStreamField[] serialPersistentFields = {
new ObjectStreamField("hostName", String.class),
new ObjectStreamField("address", int.class),
new ObjectStreamField("family", int.class),
};
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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