@Beta @GwtIncompatible 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 |
decrement(InetAddress address)
Returns a new InetAddress that is one less than the passed in address.
|
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 RFC 3986, 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 addresshostAddr
IllegalArgumentException
- 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 RFC 4291.
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 RFC 3056.
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 informationTeredoInfo
IllegalArgumentException
- 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 RFC 5214.
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 RFC 4291.
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 InetAddress
es. 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 decrement(InetAddress address)
address
- the InetAddress to decrementIllegalArgumentException
- if InetAddress is at the beginning of its rangepublic static InetAddress increment(InetAddress address)
address
- the InetAddress to incrementIllegalArgumentException
- if InetAddress is at the end of its rangepublic static boolean isMaximum(InetAddress address)
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