Class InetAddresses
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- com.google.common.net.InetAddresses
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@Beta @GwtIncompatible public final class InetAddresses extends
Static utility methods pertaining to 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 and 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:
- The IPv4 loopback address,
"127.0.0.1"
. 7f 00 00 01
- The IPv6 loopback address,
"::1"
. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
- From the IPv6 reserved documentation prefix (
2001:db8::/32
),"2001:db8::1"
. 20 01 0d b8 00 00 00 00 00 00 00 00 00 00 00 01
- An IPv6 "IPv4 compatible" (or "compat") address,
"::192.168.0.1"
. 00 00 00 00 00 00 00 00 00 00 00 00 c0 a8 00 01
- An IPv6 "IPv4 mapped" address,
"::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 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:- Since:
- 5.0
- Author:
- Erik Kline
- The IPv4 loopback address,
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
InetAddresses.TeredoInfo
A simple immutable data class to encapsulate the information to be found in a Teredo address.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static int
ip)
Returns an integer representing an IPv4 address regardless of whether the supplied argument is an IPv4 address or not.static
address)
Returns a new InetAddress that is one less than the passed in address.static
ipString)
Returns the having the given string representation.static
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
fromInteger(int address)
Returns an Inet4Address having the integer value specified by the argument.static
address)
Returns theInet4Address
corresponding to a givenBigInteger
.static
address)
Returns theInet6Address
corresponding to a givenBigInteger
.static
fromLittleEndianByteArray(byte[] addr)
Returns an address from a little-endian ordered byte array (the opposite of what expects).static
ip)
Returns the IPv4 address embedded in a 6to4 address.static
ip)
Coerces an IPv6 address into an IPv4 address.static
ip)
Returns the IPv4 address embedded in an IPv4 compatible address.static
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
ip)
Returns the IPv4 address embedded in an ISATAP address.static InetAddresses.TeredoInfo
ip)
Returns the Teredo information embedded in a Teredo address.static boolean
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
address)
Returns a new InetAddress that is one more than the passed in address.static boolean
ip)
Evaluates whether the argument is a 6to4 address.static boolean
ip)
Evaluates whether the argument is an IPv6 "compat" address.static boolean
ipString)
Returnstrue
if the supplied string is a valid IP string literal,false
otherwise.static boolean
ip)
Evaluates whether the argument is an ISATAP address.static boolean
ipString)
Evaluates whether the argument is an "IPv4 mapped" IPv6 address.static boolean
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
ip)
Evaluates whether the argument is a Teredo address.static boolean
ipString)
Returnstrue
if the supplied string is a valid URI IP string literal,false
otherwise.static
ip)
Returns the string representation of an .static
address)
Returns a BigInteger representing the address.static
ip)
Returns the string representation of an suitable for inclusion in a URI.
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Method Detail
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forString
public static ipString)
Returns the having the given string representation.This deliberately avoids all nameservice lookups (e.g. no DNS).
Anything after a
%
in an IPv6 address is ignored (assumed to be a Scope ID).- Parameters:
ipString
-String
containing an IPv4 or IPv6 string literal, e.g."192.168.0.1"
or"2001:db8::1"
- Returns:
- representing the argument
- Throws:
- if the argument is not a valid IP string literal
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isInetAddress
public static boolean ipString)
Returnstrue
if the supplied string is a valid IP string literal,false
otherwise.- Parameters:
ipString
-String
to evaluated as an IP string literal- Returns:
true
if the argument is a valid IP string literal
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toAddrString
public static ip)
Returns the string representation of an .For IPv4 addresses, this is identical to , but for IPv6 addresses, the output follows 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.
- Parameters:
ip
- to be converted to an address string- Returns:
String
containing the text-formatted IP address- Since:
- 10.0
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toUriString
public static ip)
Returns the string representation of an suitable for inclusion in a URI.For IPv4 addresses, this is identical to , 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 , a URI containing an IPv6 string literal is of the form
"http://[2001:db8::1]:8888/index.html"
.Use of either , or this method is recommended over when an IP address string literal is desired. This is because prints the hostname and the IP address string joined by a "/".
- Parameters:
ip
- to be converted to URI string literal- Returns:
String
containing URI-safe string literal
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forUriString
public static 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.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)
.- Parameters:
hostAddr
- A RFC 3986 section 3.2.2 encoded IPv4 or IPv6 address- Returns:
- an InetAddress representing the address in
hostAddr
- Throws:
- if
hostAddr
is not a valid IPv4 address, or IPv6 address surrounded by square brackets
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isUriInetAddress
public static boolean ipString)
Returnstrue
if the supplied string is a valid URI IP string literal,false
otherwise.- Parameters:
ipString
-String
to evaluated as an IP URI host string literal- Returns:
true
if the argument is a valid IP URI host
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isCompatIPv4Address
public static boolean ip)
Evaluates whether the argument is an IPv6 "compat" address.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 .
NOTE: This method is different from 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).- Parameters:
ip
- to be examined for embedded IPv4 compatible address format- Returns:
true
if the argument is a valid "compat" address
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getCompatIPv4Address
public static ip)
Returns the IPv4 address embedded in an IPv4 compatible address.- Parameters:
ip
- to be examined for an embedded IPv4 address- Returns:
- of the embedded IPv4 address
- Throws:
- if the argument is not a valid IPv4 compatible address
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is6to4Address
public static boolean ip)
Evaluates whether the argument is a 6to4 address.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 .
- Parameters:
ip
- to be examined for 6to4 address format- Returns:
true
if the argument is a 6to4 address
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get6to4IPv4Address
public static ip)
Returns the IPv4 address embedded in a 6to4 address.- Parameters:
ip
- to be examined for embedded IPv4 in 6to4 address- Returns:
- of embedded IPv4 in 6to4 address
- Throws:
- if the argument is not a valid IPv6 6to4 address
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isTeredoAddress
public static boolean ip)
Evaluates whether the argument is a Teredo address.Teredo addresses begin with the
"2001::/32"
prefix.- Parameters:
ip
- to be examined for Teredo address format- Returns:
true
if the argument is a Teredo address
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getTeredoInfo
public static ip)
Returns the Teredo information embedded in a Teredo address.- Parameters:
ip
- to be examined for embedded Teredo information- Returns:
- extracted
TeredoInfo
- Throws:
- if the argument is not a valid IPv6 Teredo address
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isIsatapAddress
public static boolean ip)
Evaluates whether the argument is an ISATAP address.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 .
- Parameters:
ip
- to be examined for ISATAP address format- Returns:
true
if the argument is an ISATAP address
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getIsatapIPv4Address
public static ip)
Returns the IPv4 address embedded in an ISATAP address.- Parameters:
ip
- to be examined for embedded IPv4 in ISATAP address- Returns:
- of embedded IPv4 in an ISATAP address
- Throws:
- if the argument is not a valid IPv6 ISATAP address
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hasEmbeddedIPv4ClientAddress
public static boolean 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.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.
- Parameters:
ip
- to be examined for embedded IPv4 client address- Returns:
true
if there is an embedded IPv4 client address- Since:
- 7.0
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getEmbeddedIPv4ClientAddress
public static 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.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.
- Parameters:
ip
- to be examined for embedded IPv4 client address- Returns:
- of embedded IPv4 client address
- Throws:
- if the argument does not have a valid embedded IPv4 address
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isMappedIPv4Address
public static boolean ipString)
Evaluates whether the argument is an "IPv4 mapped" IPv6 address.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 .
Note: This method takes a
String
argument because automatically collapses mapped addresses to IPv4. (It is actually possible to avoid this using one of the obscure methods, but it would be unwise to depend on such a poorly-documented feature.)- Parameters:
ipString
-String
to be examined for embedded IPv4-mapped IPv6 address format- Returns:
true
if the argument is a valid "mapped" address- Since:
- 10.0
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getCoercedIPv4Address
public static ip)
Coerces an IPv6 address into an IPv4 address.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 64 bits of the IPv6 address into
224.0.0.0/3
(64 bits into 29 bits):- If the IPv6 address contains an embedded IPv4 address, the function hashes that.
- Otherwise, it hashes the upper 64 bits of the IPv6 address.
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.
- Parameters:
ip
- to "coerce"- Returns:
- represented "coerced" address
- Since:
- 7.0
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coerceToInteger
public static int ip)
Returns an integer representing an IPv4 address regardless of whether the supplied argument is an IPv4 address or not.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 es. They cannot be used as real addresses for the purposes of network communication.
- Parameters:
ip
- to convert- Returns:
int
, "coerced" if ip is not an IPv4 address- Since:
- 7.0
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toBigInteger
public static address)
Returns a BigInteger representing the address.Unlike
coerceToInteger
, IPv6 addresses are not coerced to IPv4 addresses.- Parameters:
address
- to convert- Returns:
BigInteger
representation of the address- Since:
- 28.2
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fromInteger
public static fromInteger(int address)
Returns an Inet4Address having the integer value specified by the argument.- Parameters:
address
-int
, the 32bit integer address to be converted- Returns:
- equivalent of the argument
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fromIPv4BigInteger
public static address)
Returns theInet4Address
corresponding to a givenBigInteger
.- Parameters:
address
- BigInteger representing the IPv4 address- Returns:
- Inet4Address representation of the given BigInteger
- Throws:
- if the BigInteger is not between 0 and 2^32-1
- Since:
- 28.2
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fromIPv6BigInteger
public static address)
Returns theInet6Address
corresponding to a givenBigInteger
.- Parameters:
address
- BigInteger representing the IPv6 address- Returns:
- Inet6Address representation of the given BigInteger
- Throws:
- if the BigInteger is not between 0 and 2^128-1
- Since:
- 28.2
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fromLittleEndianByteArray
public static fromLittleEndianByteArray(byte[] addr) throws
Returns an address from a little-endian ordered byte array (the opposite of what expects).IPv4 address byte array must be 4 bytes long and IPv6 byte array must be 16 bytes long.
- Parameters:
addr
- the raw IP address in little-endian byte order- Returns:
- an InetAddress object created from the raw IP address
- Throws:
- if IP address is of illegal length
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decrement
public static address)
Returns a new InetAddress that is one less than the passed in address. This method works for both IPv4 and IPv6 addresses.- Parameters:
address
- the InetAddress to decrement- Returns:
- a new InetAddress that is one less than the passed in address
- Throws:
- if InetAddress is at the beginning of its range
- Since:
- 18.0
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increment
public static address)
Returns a new InetAddress that is one more than the passed in address. This method works for both IPv4 and IPv6 addresses.- Parameters:
address
- the InetAddress to increment- Returns:
- a new InetAddress that is one more than the passed in address
- Throws:
- if InetAddress is at the end of its range
- Since:
- 10.0
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isMaximum
public static boolean 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.- Returns:
- true if the InetAddress is either 255.255.255.255 for IPv4 or ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff for IPv6
- Since:
- 10.0
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