@Beta public final class InetAddresses extends Object
InetAddress instances.
Important note: Unlike InetAddress.getByName(), the
methods of this class never cause DNS services to be accessed. For
this reason, you should prefer these methods as much as possible over
their JDK equivalents whenever you are expecting to handle only
IP address string literals -- there is no blocking DNS penalty for a
malformed string.
When dealing with Inet4Address and Inet6Address
objects as byte arrays (vis. InetAddress.getAddress()) they
are 4 and 16 bytes in length, respectively, and represent the address
in network byte order.
Examples of IP addresses and their byte representations:
"127.0.0.1".7f 00 00 01
"::1".00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
2001:db8::/32),
"2001:db8::1".20 01 0d b8 00 00 00 00 00 00 00 00 00 00 00 01
"::192.168.0.1".00 00 00 00 00 00 00 00 00 00 00 00 c0 a8 00 01
"::ffff:192.168.0.1".00 00 00 00 00 00 00 00 00 00 ff ff c0 a8 00 01
A few notes about IPv6 "IPv4 mapped" addresses and their observed
use in Java.
"IPv4 mapped" addresses were originally a representation of IPv4
addresses for use on an IPv6 socket that could receive both IPv4
and IPv6 connections (by disabling the IPV6_V6ONLY socket
option on an IPv6 socket). Yes, it's confusing. Nevertheless,
these "mapped" addresses were never supposed to be seen on the
wire. That assumption was dropped, some say mistakenly, in later
RFCs with the apparent aim of making IPv4-to-IPv6 transition simpler.
Technically one can create a 128bit IPv6 address with the wire
format of a "mapped" address, as shown above, and transmit it in an
IPv6 packet header. However, Java's InetAddress creation methods
appear to adhere doggedly to the original intent of the "mapped"
address: all "mapped" addresses return Inet4Address objects.
For added safety, it is common for IPv6 network operators to filter
all packets where either the source or destination address appears to
be a "compat" or "mapped" address. Filtering suggestions usually
recommend discarding any packets with source or destination addresses
in the invalid range ::/3, which includes both of these bizarre
address formats. For more information on "bogons", including lists
of IPv6 bogon space, see:
| Modifier and Type | Class and Description |
|---|---|
static class |
InetAddresses.TeredoInfo
A simple immutable data class to encapsulate the information to be found in a
Teredo address.
|
| Modifier and Type | Method and Description |
|---|---|
static int |
coerceToInteger(InetAddress ip)
Returns an integer representing an IPv4 address regardless of
whether the supplied argument is an IPv4 address or not.
|
static InetAddress |
forString(String ipString)
Returns the
InetAddress having the given string representation. |
static InetAddress |
forUriString(String hostAddr)
Returns an InetAddress representing the literal IPv4 or IPv6 host
portion of a URL, encoded in the format specified by RFC 3986 section 3.2.2.
|
static Inet4Address |
fromInteger(int address)
Returns an Inet4Address having the integer value specified by
the argument.
|
static InetAddress |
fromLittleEndianByteArray(byte[] addr)
Returns an address from a little-endian ordered byte array
(the opposite of what
InetAddress.getByAddress(java.lang.String, byte[]) expects). |
static Inet4Address |
get6to4IPv4Address(Inet6Address ip)
Returns the IPv4 address embedded in a 6to4 address.
|
static Inet4Address |
getCoercedIPv4Address(InetAddress ip)
Coerces an IPv6 address into an IPv4 address.
|
static Inet4Address |
getCompatIPv4Address(Inet6Address ip)
Returns the IPv4 address embedded in an IPv4 compatible address.
|
static Inet4Address |
getEmbeddedIPv4ClientAddress(Inet6Address ip)
Examines the Inet6Address to extract the embedded IPv4 client address
if the InetAddress is an IPv6 address of one of the specified address
types that contain an embedded IPv4 address.
|
static Inet4Address |
getIsatapIPv4Address(Inet6Address ip)
Returns the IPv4 address embedded in an ISATAP address.
|
static InetAddresses.TeredoInfo |
getTeredoInfo(Inet6Address ip)
Returns the Teredo information embedded in a Teredo address.
|
static boolean |
hasEmbeddedIPv4ClientAddress(Inet6Address ip)
Examines the Inet6Address to determine if it is an IPv6 address of one
of the specified address types that contain an embedded IPv4 address.
|
static InetAddress |
increment(InetAddress address)
Returns a new InetAddress that is one more than the passed in address.
|
static boolean |
is6to4Address(Inet6Address ip)
Evaluates whether the argument is a 6to4 address.
|
static boolean |
isCompatIPv4Address(Inet6Address ip)
Evaluates whether the argument is an IPv6 "compat" address.
|
static boolean |
isInetAddress(String ipString)
Returns
true if the supplied string is a valid IP string
literal, false otherwise. |
static boolean |
isIsatapAddress(Inet6Address ip)
Evaluates whether the argument is an ISATAP address.
|
static boolean |
isMappedIPv4Address(String ipString)
Evaluates whether the argument is an "IPv4 mapped" IPv6 address.
|
static boolean |
isMaximum(InetAddress address)
Returns true if the InetAddress is either 255.255.255.255 for IPv4 or
ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff for IPv6.
|
static boolean |
isTeredoAddress(Inet6Address ip)
Evaluates whether the argument is a Teredo address.
|
static boolean |
isUriInetAddress(String ipString)
Returns
true if the supplied string is a valid URI IP string
literal, false otherwise. |
static String |
toAddrString(InetAddress ip)
Returns the string representation of an
InetAddress. |
static String |
toUriString(InetAddress ip)
Returns the string representation of an
InetAddress suitable
for inclusion in a URI. |
public static InetAddress forString(String ipString)
InetAddress having the given string representation.
This deliberately avoids all nameservice lookups (e.g. no DNS).
ipString - String containing an IPv4 or IPv6 string literal, e.g.
"192.168.0.1" or "2001:db8::1"InetAddress representing the argumentIllegalArgumentException - if the argument is not a valid IP string literalpublic static boolean isInetAddress(String ipString)
true if the supplied string is a valid IP string
literal, false otherwise.ipString - String to evaluated as an IP string literaltrue if the argument is a valid IP string literalpublic static String toAddrString(InetAddress ip)
InetAddress.
For IPv4 addresses, this is identical to
InetAddress.getHostAddress(), but for IPv6 addresses, the output
follows RFC 5952
section 4. The main difference is that this method uses "::" for zero
compression, while Java's version uses the uncompressed form.
This method uses hexadecimal for all IPv6 addresses, including IPv4-mapped IPv6 addresses such as "::c000:201". The output does not include a Scope ID.
ip - InetAddress to be converted to an address stringString containing the text-formatted IP addresspublic static String toUriString(InetAddress ip)
InetAddress suitable
for inclusion in a URI.
For IPv4 addresses, this is identical to
InetAddress.getHostAddress(), but for IPv6 addresses it
compresses zeroes and surrounds the text with square brackets; for example
"[2001:db8::1]".
Per section 3.2.2 of
http://tools.ietf.org/html/rfc3986,
a URI containing an IPv6 string literal is of the form
"http://[2001:db8::1]:8888/index.html".
Use of either toAddrString(java.net.InetAddress),
InetAddress.getHostAddress(), or this method is recommended over
InetAddress.toString() when an IP address string literal is
desired. This is because InetAddress.toString() prints the
hostname and the IP address string joined by a "/".
ip - InetAddress to be converted to URI string literalString containing URI-safe string literalpublic static InetAddress forUriString(String hostAddr)
This function is similar to forString(String),
however, it requires that IPv6 addresses are surrounded by square brackets.
This function is the inverse of
toUriString(java.net.InetAddress).
hostAddr - A RFC 3986 section 3.2.2 encoded IPv4 or IPv6 addresshostAddrIllegalArgumentException - if hostAddr is not a valid
IPv4 address, or IPv6 address surrounded by square bracketspublic static boolean isUriInetAddress(String ipString)
true if the supplied string is a valid URI IP string
literal, false otherwise.ipString - String to evaluated as an IP URI host string literaltrue if the argument is a valid IP URI hostpublic static boolean isCompatIPv4Address(Inet6Address ip)
An "IPv4 compatible", or "compat", address is one with 96 leading
bits of zero, with the remaining 32 bits interpreted as an
IPv4 address. These are conventionally represented in string
literals as "::192.168.0.1", though "::c0a8:1" is
also considered an IPv4 compatible address (and equivalent to
"::192.168.0.1").
For more on IPv4 compatible addresses see section 2.5.5.1 of http://tools.ietf.org/html/rfc4291
NOTE: This method is different from
Inet6Address.isIPv4CompatibleAddress() in that it more
correctly classifies "::" and "::1" as
proper IPv6 addresses (which they are), NOT IPv4 compatible
addresses (which they are generally NOT considered to be).
ip - Inet6Address to be examined for embedded IPv4 compatible address formattrue if the argument is a valid "compat" addresspublic static Inet4Address getCompatIPv4Address(Inet6Address ip)
ip - Inet6Address to be examined for an embedded IPv4 addressInet4Address of the embedded IPv4 addressIllegalArgumentException - if the argument is not a valid IPv4 compatible addresspublic static boolean is6to4Address(Inet6Address ip)
6to4 addresses begin with the "2002::/16" prefix.
The next 32 bits are the IPv4 address of the host to which
IPv6-in-IPv4 tunneled packets should be routed.
For more on 6to4 addresses see section 2 of http://tools.ietf.org/html/rfc3056
ip - Inet6Address to be examined for 6to4 address formattrue if the argument is a 6to4 addresspublic static Inet4Address get6to4IPv4Address(Inet6Address ip)
ip - Inet6Address to be examined for embedded IPv4 in 6to4 addressInet4Address of embedded IPv4 in 6to4 addressIllegalArgumentException - if the argument is not a valid IPv6 6to4 addresspublic static boolean isTeredoAddress(Inet6Address ip)
Teredo addresses begin with the "2001::/32" prefix.
ip - Inet6Address to be examined for Teredo address formattrue if the argument is a Teredo addresspublic static InetAddresses.TeredoInfo getTeredoInfo(Inet6Address ip)
ip - Inet6Address to be examined for embedded Teredo informationTeredoInfoIllegalArgumentException - if the argument is not a valid IPv6 Teredo addresspublic static boolean isIsatapAddress(Inet6Address ip)
From RFC 5214: "ISATAP interface identifiers are constructed in Modified EUI-64 format [...] by concatenating the 24-bit IANA OUI (00-00-5E), the 8-bit hexadecimal value 0xFE, and a 32-bit IPv4 address in network byte order [...]"
For more on ISATAP addresses see section 6.1 of http://tools.ietf.org/html/rfc5214
ip - Inet6Address to be examined for ISATAP address formattrue if the argument is an ISATAP addresspublic static Inet4Address getIsatapIPv4Address(Inet6Address ip)
ip - Inet6Address to be examined for embedded IPv4 in ISATAP addressInet4Address of embedded IPv4 in an ISATAP addressIllegalArgumentException - if the argument is not a valid IPv6 ISATAP addresspublic static boolean hasEmbeddedIPv4ClientAddress(Inet6Address ip)
NOTE: ISATAP addresses are explicitly excluded from this method due to their trivial spoofability. With other transition addresses spoofing involves (at least) infection of one's BGP routing table.
ip - Inet6Address to be examined for embedded IPv4 client addresstrue if there is an embedded IPv4 client addresspublic static Inet4Address getEmbeddedIPv4ClientAddress(Inet6Address ip)
NOTE: ISATAP addresses are explicitly excluded from this method due to their trivial spoofability. With other transition addresses spoofing involves (at least) infection of one's BGP routing table.
ip - Inet6Address to be examined for embedded IPv4 client addressInet4Address of embedded IPv4 client addressIllegalArgumentException - if the argument does not have a valid embedded IPv4 addresspublic static boolean isMappedIPv4Address(String ipString)
An "IPv4 mapped" address is anything in the range ::ffff:0:0/96 (sometimes written as ::ffff:0.0.0.0/96), with the last 32 bits interpreted as an IPv4 address.
For more on IPv4 mapped addresses see section 2.5.5.2 of http://tools.ietf.org/html/rfc4291
Note: This method takes a String argument because
InetAddress automatically collapses mapped addresses to IPv4.
(It is actually possible to avoid this using one of the obscure
Inet6Address methods, but it would be unwise to depend on such
a poorly-documented feature.)
ipString - String to be examined for embedded IPv4-mapped IPv6 address formattrue if the argument is a valid "mapped" addresspublic static Inet4Address getCoercedIPv4Address(InetAddress ip)
HACK: As long as applications continue to use IPv4 addresses for
indexing into tables, accounting, et cetera, it may be necessary to
coerce IPv6 addresses into IPv4 addresses. This function does
so by hashing the upper 64 bits into 224.0.0.0/3
(64 bits into 29 bits).
A "coerced" IPv4 address is equivalent to itself.
NOTE: This function is failsafe for security purposes: ALL IPv6 addresses (except localhost (::1)) are hashed to avoid the security risk associated with extracting an embedded IPv4 address that might permit elevated privileges.
ip - InetAddress to "coerce"Inet4Address represented "coerced" addresspublic static int coerceToInteger(InetAddress ip)
IPv6 addresses are coerced to IPv4 addresses before being converted to integers.
As long as there are applications that assume that all IP addresses are IPv4 addresses and can therefore be converted safely to integers (for whatever purpose) this function can be used to handle IPv6 addresses as well until the application is suitably fixed.
NOTE: an IPv6 address coerced to an IPv4 address can only be used
for such purposes as rudimentary identification or indexing into a
collection of real InetAddresses. They cannot be used as
real addresses for the purposes of network communication.
ip - InetAddress to convertint, "coerced" if ip is not an IPv4 addresspublic static Inet4Address fromInteger(int address)
address - int, the 32bit integer address to be convertedInet4Address equivalent of the argumentpublic static InetAddress fromLittleEndianByteArray(byte[] addr) throws UnknownHostException
InetAddress.getByAddress(java.lang.String, byte[]) expects).
IPv4 address byte array must be 4 bytes long and IPv6 byte array must be 16 bytes long.
addr - the raw IP address in little-endian byte orderUnknownHostException - if IP address is of illegal lengthpublic static InetAddress increment(InetAddress address)
address - the InetAddress to incrementIllegalArgumentException - if InetAddress is at the end of its rangepublic static boolean isMaximum(InetAddress address)
Copyright © 2020. All rights reserved.