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1885 lines (1740 loc) · 74.8 KB
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/*
* Copyright (c) 1995, 2025, 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.net.spi.InetAddressResolver;
import java.net.spi.InetAddressResolverProvider;
import java.net.spi.InetAddressResolver.LookupPolicy;
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.io.Serializable;
import java.lang.annotation.Native;
import java.util.ServiceLoader;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentSkipListSet;
import java.util.concurrent.atomic.AtomicLong;
import java.util.Arrays;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.stream.Stream;
import jdk.internal.util.Exceptions;
import jdk.internal.access.JavaNetInetAddressAccess;
import jdk.internal.access.SharedSecrets;
import jdk.internal.misc.Blocker;
import jdk.internal.misc.VM;
import jdk.internal.vm.annotation.Stable;
import sun.net.ResolverProviderConfiguration;
import sun.net.InetAddressCachePolicy;
import sun.net.util.IPAddressUtil;
import sun.nio.cs.UTF_8;
import static java.net.spi.InetAddressResolver.LookupPolicy.IPV4;
import static java.net.spi.InetAddressResolver.LookupPolicy.IPV4_FIRST;
import static java.net.spi.InetAddressResolver.LookupPolicy.IPV6;
import static java.net.spi.InetAddressResolver.LookupPolicy.IPV6_FIRST;
import static jdk.internal.util.Exceptions.filterNonSocketInfo;
import static jdk.internal.util.Exceptions.formatMsg;
/**
* 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> <a id="format">Textual representation of IP addresses</a> </h3>
*
* The textual representation of an IP address is address family specific.
*
* <p>
*
* For IPv4 address format, please refer to the supported
* {@linkplain Inet4Address##format IPv4 address textual representations};
* For IPv6 address format, please refer to the supported
* {@linkplain Inet6Address##format IPv6 address textual representations}.
*
* <p> There are a <a href="doc-files/net-properties.html#Ipv4IPv6">couple of
* System Properties</a> affecting how IPv4 and IPv6 addresses are used.
*
* <h2 id="host-name-resolution"> Host Name Resolution </h2>
*
* <p> The InetAddress class provides methods to resolve host names to
* their IP addresses and vice versa. The actual resolution is delegated to an
* {@linkplain InetAddressResolver InetAddress resolver}.
*
* <p> <i>Host name-to-IP address resolution</i> maps a host name to an IP address.
* 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 id="built-in-resolver"> The built-in InetAddress resolver implementation does
* host name-to-IP address resolution and vice versa through the use of
* a combination of local machine configuration information and network
* naming services such as the Domain Name System (DNS) and the Lightweight Directory
* Access Protocol (LDAP).
* The particular naming services that the built-in resolver uses by default
* depends on the configuration of the local machine.
*
* <p> {@code InetAddress} has a service provider mechanism for InetAddress resolvers
* that allows a custom InetAddress resolver to be used instead of the built-in implementation.
* {@link InetAddressResolverProvider} is the service provider class. Its API docs provide all the
* details on this mechanism.
*
* <h2> InetAddress Caching </h2>
*
* The InetAddress class has a cache to store successful as well as
* unsuccessful host name resolutions.
*
* <p> 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 or extend the usage of the stale data.
*
* <p> Three Java {@linkplain java.security.Security 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.stale.ttl</b></dt>
* <dd>Indicates the caching policy for stale names. The value is specified as
* an integer to indicate the number of seconds that stale names will be kept in
* the cache. A name is considered stale if the TTL has expired and an attempt
* to lookup the host name again was not successful. This property is useful if
* it is preferable to use a stale name rather than fail due to an unsuccessful
* lookup. The default setting is to cache for an implementation specific period
* of time.
* <p>
* If the value of this property is larger than "networkaddress.cache.ttl" then
* "networkaddress.cache.ttl" will be used as a refresh interval of the name in
* the cache. For example, if this property is set to 1 day and
* "networkaddress.cache.ttl" is set to 30 seconds, then the positive response
* will be cached for 1 day but an attempt to refresh it will be done every
* 30 seconds.
* <p>
* A value of 0 (zero) or if the property is not set means do not use stale
* names. Negative values are ignored.
* </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>
*
* @spec https://www.rfc-editor.org/info/rfc1918
* RFC 1918: Address Allocation for Private Internets
* @spec https://www.rfc-editor.org/info/rfc2365
* RFC 2365: Administratively Scoped IP Multicast
* @spec https://www.rfc-editor.org/info/rfc2373
* RFC 2373: IP Version 6 Addressing Architecture
* @spec https://www.rfc-editor.org/info/rfc790
* RFC 790: Assigned numbers
* @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
* @sealedGraph
*/
public sealed class InetAddress implements Serializable permits Inet4Address, Inet6Address {
/**
* 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;
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 system-wide resolver */
@Stable
private static volatile InetAddressResolver resolver;
private static final InetAddressResolver BUILTIN_RESOLVER;
/**
* 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;
// "java.net.preferIPv4Stack" system property value
private static final String PREFER_IPV4_STACK_VALUE;
// "java.net.preferIPv6Addresses" system property value
private static final String PREFER_IPV6_ADDRESSES_VALUE;
// "jdk.net.hosts.file" system property value
private static final String HOSTS_FILE_NAME;
/*
* Load net library into runtime, and perform initializations.
*/
static {
PREFER_IPV4_STACK_VALUE =
System.getProperty("java.net.preferIPv4Stack");
PREFER_IPV6_ADDRESSES_VALUE =
System.getProperty("java.net.preferIPv6Addresses");
HOSTS_FILE_NAME =
System.getProperty("jdk.net.hosts.file");
jdk.internal.loader.BootLoader.loadLibrary("net");
SharedSecrets.setJavaNetInetAddressAccess(
new JavaNetInetAddressAccess() {
public String getOriginalHostName(InetAddress ia) {
return ia.holder.getOriginalHostName();
}
public int addressValue(Inet4Address inet4Address) {
return inet4Address.addressValue();
}
public byte[] addressBytes(Inet6Address inet6Address) {
return inet6Address.addressBytes();
}
}
);
Exceptions.setup(); // needed for native exceptions
init();
}
/**
* Creates an address lookup policy from {@code "java.net.preferIPv4Stack"},
* {@code "java.net.preferIPv6Addresses"} system property values, and O/S configuration.
*/
private static final LookupPolicy initializePlatformLookupPolicy() {
// Calculate AddressFamily value first
boolean ipv4Available = isIPv4Available();
if ("true".equals(PREFER_IPV4_STACK_VALUE) && ipv4Available) {
return LookupPolicy.of(IPV4);
}
// Check if IPv6 is not supported
if (InetAddress.impl instanceof Inet4AddressImpl) {
return LookupPolicy.of(IPV4);
}
// Check if system supports IPv4, if not use IPv6
if (!ipv4Available) {
return LookupPolicy.of(IPV6);
}
// If both address families are needed - check preferIPv6Addresses value
if (PREFER_IPV6_ADDRESSES_VALUE != null) {
if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("true")) {
return LookupPolicy.of(IPV4 | IPV6 | IPV6_FIRST);
}
if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("false")) {
return LookupPolicy.of(IPV4 | IPV6 | IPV4_FIRST);
}
if (PREFER_IPV6_ADDRESSES_VALUE.equalsIgnoreCase("system")) {
return LookupPolicy.of(IPV4 | IPV6);
}
}
// Default value with both address families needed - IPv4 addresses come first
return LookupPolicy.of(IPV4 | IPV6 | IPV4_FIRST);
}
static boolean systemAddressesOrder(int lookupCharacteristics) {
return (lookupCharacteristics & (IPV4_FIRST | IPV6_FIRST)) == 0;
}
static boolean ipv4AddressesFirst(int lookupCharacteristics) {
return (lookupCharacteristics & IPV4_FIRST) != 0;
}
static boolean ipv6AddressesFirst(int lookupCharacteristics) {
return (lookupCharacteristics & IPV6_FIRST) != 0;
}
// Native method to check if IPv4 is available
private static native boolean isIPv4Available();
// Native method to check if IPv6 is available
private static native boolean isIPv6Supported();
private static final ReentrantLock RESOLVER_LOCK = new ReentrantLock();
private static volatile InetAddressResolver bootstrapResolver;
private static InetAddressResolver resolver() {
InetAddressResolver cns = resolver;
if (cns != null) {
return cns;
}
if (VM.isBooted()) {
RESOLVER_LOCK.lock();
boolean bootstrapSet = false;
try {
cns = resolver;
if (cns != null) {
return cns;
}
// Protection against provider calling InetAddress APIs during initialization
if (bootstrapResolver != null) {
return bootstrapResolver;
}
bootstrapResolver = BUILTIN_RESOLVER;
bootstrapSet = true;
if (HOSTS_FILE_NAME != null) {
// The default resolver service is already host file resolver
cns = BUILTIN_RESOLVER;
} else {
cns = loadResolver();
}
InetAddress.resolver = cns;
return cns;
} finally {
// We want to clear bootstrap resolver reference only after an attempt to
// instantiate a resolver has been completed.
if (bootstrapSet) {
bootstrapResolver = null;
}
RESOLVER_LOCK.unlock();
}
} else {
return BUILTIN_RESOLVER;
}
}
private static InetAddressResolver loadResolver() {
return ServiceLoader.load(InetAddressResolverProvider.class)
.findFirst()
.map(nsp -> nsp.get(builtinConfiguration()))
.orElse(BUILTIN_RESOLVER);
}
private static InetAddressResolverProvider.Configuration builtinConfiguration() {
return new ResolverProviderConfiguration(BUILTIN_RESOLVER, () -> {
try {
return impl.getLocalHostName();
} catch (UnknownHostException unknownHostException) {
return "localhost";
}
});
}
/**
* 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 a 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 an 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-wide
* resolver. If a lookup of the name service
* is required, call
* {@link #getCanonicalHostName() getCanonicalHostName}.
*
* @return the host name for this IP address
*
* @see InetAddress#getCanonicalHostName
*/
public String getHostName() {
if (holder().getHostName() == null) {
holder().hostName = InetAddress.getHostFromNameService(this);
}
return holder().getHostName();
}
/**
* Gets the fully qualified domain name for this
* {@linkplain InetAddress#getAddress() IP address} using the system-wide
* {@linkplain InetAddressResolver resolver}.
*
* <p>The system-wide resolver will be used to do a reverse name lookup of the IP address.
* The lookup can fail for many reasons that include the host not being registered with the name
* service. If the resolver is unable to determine the fully qualified
* domain name, this method returns the {@linkplain #getHostAddress() textual representation}
* of the IP address.
*
* @return the fully qualified domain name for this IP address.
* If the system-wide resolver wasn't able to determine the
* fully qualified domain name for the IP address, the textual
* representation of the IP address is returned instead.
*
* @since 1.4
*/
public String getCanonicalHostName() {
String value = canonicalHostName;
if (value == null)
canonicalHostName = value =
InetAddress.getHostFromNameService(this);
return value;
}
/**
* Returns the fully qualified domain name for the given address.
*
* @return the fully qualified domain name for the given IP address.
* If the system-wide resolver wasn't able to determine the
* fully qualified domain name for the IP address, the textual
* representation of the IP address is returned instead.
*/
private static String getHostFromNameService(InetAddress addr) {
String host;
var resolver = resolver();
try {
// first lookup the hostname
host = resolver.lookupByAddress(addr.getAddress());
/* 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);
boolean ok = false;
if (arr != null) {
for (int i = 0; !ok && i < arr.length; i++) {
ok = addr.equals(arr[i]);
}
}
//XXX: if it looks like a spoof just return the address?
if (!ok) {
host = addr.getHostAddress();
return host;
}
} catch (RuntimeException | UnknownHostException e) {
// 'resolver.lookupByAddress' and 'InetAddress.getAllByName0' delegate to
// the system-wide resolver, which could be a custom one. At that point we
// treat any unexpected RuntimeException thrown by the resolver as we would
// treat an UnknownHostException or an unmatched host name.
host = addr.getHostAddress();
}
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 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<CachedLookup> expirySet =
new ConcurrentSkipListSet<>();
// common interface
private interface Addresses {
InetAddress[] get() throws UnknownHostException;
}
/**
* A cached result of a name service lookup. The result can be either valid
* addresses or invalid (ie a failed lookup) containing no addresses.
*/
private static class CachedLookup implements Addresses, Comparable<CachedLookup> {
private static final AtomicLong seq = new AtomicLong();
final String host;
volatile InetAddress[] inetAddresses;
/**
* Time of expiry (in terms of System.nanoTime()). Can be modified only
* when the record is not added to the "expirySet".
*/
volatile long expiryTime;
final long id = seq.incrementAndGet(); // each instance is unique
CachedLookup(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(formatMsg("%s", filterNonSocketInfo(host)));
}
return inetAddresses;
}
@Override
public int compareTo(CachedLookup 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);
}
/**
* Checks if the current cache record is expired or not. Expired records
* are removed from the expirySet and cache.
*
* @return {@code true} if the record was removed
*/
public boolean tryRemoveExpiredAddress(long now) {
// compare difference of time instants rather than
// time instants directly, to avoid possible overflow.
// (see System.nanoTime() recommendations...)
if ((expiryTime - now) < 0L) {
// ConcurrentSkipListSet uses weakly consistent iterator,
// so removing while iterating is OK...
if (expirySet.remove(this)) {
// ... remove from cache
cache.remove(host, this);
}
return true;
}
return false;
}
}
/**
* A cached valid lookup containing addresses whose validity may be
* temporarily extended by an additional stale period pending the mapping
* being refreshed or updated.
*/
private static final class ValidCachedLookup extends CachedLookup {
/**
* Time to refresh (in terms of System.nanoTime()).
*/
private volatile long refreshTime;
/**
* For how long the stale data should be used after TTL expiration.
* Initially equal to the expiryTime, but increased over time after each
* successful lookup.
*/
private volatile long staleTime;
/**
* only one thread is doing lookup to name service
* for particular host at any time.
*/
private final Lock lookupLock = new ReentrantLock();
ValidCachedLookup(String host, InetAddress[] inetAddresses,
long staleTime, long refreshTime)
{
super(host, inetAddresses, staleTime);
this.refreshTime = refreshTime;
this.staleTime = staleTime;
}
@Override
public InetAddress[] get() {
long now = System.nanoTime();
if ((refreshTime - now) < 0L && lookupLock.tryLock()) {
try {
// cachePolicy is in [s] - we need [ns]
refreshTime = now + InetAddressCachePolicy.get() * 1000_000_000L;
// getAddressesFromNameService returns non-empty/non-null value
inetAddresses = getAddressesFromNameService(host);
// don't update the "expirySet", will do that later
staleTime = refreshTime + InetAddressCachePolicy.getStale() * 1000_000_000L;
} catch (UnknownHostException ignore) {
} finally {
lookupLock.unlock();
}
}
return inetAddresses;
}
/**