io.netty.util

Class NetUtil

java.lang.Object

io.netty.util.NetUtil

public final class NetUtil
extends Object

A class that holds a number of network-related constants.

This class borrowed some of its methods from a modified fork of the Inet6Util class which was part of Apache Harmony.

Field Summary

Fields

Modifier and Type	Field and Description
static InetAddress	LOCALHOST The InetAddress that represents the loopback address.
static Inet4Address	LOCALHOST4 The Inet4Address that represents the IPv4 loopback address '127.0.0.1'
static Inet6Address	LOCALHOST6 The Inet6Address that represents the IPv6 loopback address '::1'
static NetworkInterface	LOOPBACK_IF The loopback NetworkInterface of the current machine
static int	SOMAXCONN The SOMAXCONN value of the current machine.

Method Summary

Methods

Modifier and Type	Method and Description
static String	bytesToIpAddress(byte[] bytes, int offset, int length) Converts 4-byte or 16-byte data into an IPv4 or IPv6 string respectively.
static byte[]	createByteArrayFromIpAddressString(String ipAddressString) Creates an byte[] based on an ipAddressString.
static Inet6Address	getByName(CharSequence ip) Returns the Inet6Address representation of a CharSequence IP address.
static Inet6Address	getByName(CharSequence ip, boolean ipv4Mapped) Returns the Inet6Address representation of a CharSequence IP address.
static String	intToIpAddress(int i) Converts a 32-bit integer into an IPv4 address.
static boolean	isIpV4StackPreferred() Returns true if ipv4 should be prefered on a system that supports ipv4 and ipv6.
static boolean	isValidIpV4Address(String value) Takes a string and parses it to see if it is a valid IPV4 address.
static boolean	isValidIpV6Address(String ipAddress)
static String	toAddressString(InetAddress ip) Returns the String representation of an InetAddress.
static String	toAddressString(InetAddress ip, boolean ipv4Mapped) Returns the String representation of an InetAddress.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOCALHOST4

public static final Inet4Address LOCALHOST4

The Inet4Address that represents the IPv4 loopback address '127.0.0.1'

LOCALHOST6

public static final Inet6Address LOCALHOST6

The Inet6Address that represents the IPv6 loopback address '::1'

LOCALHOST

public static final InetAddress LOCALHOST

The InetAddress that represents the loopback address. If IPv6 stack is available, it will refer to LOCALHOST6. Otherwise, LOCALHOST4.

LOOPBACK_IF

public static final NetworkInterface LOOPBACK_IF

The loopback NetworkInterface of the current machine

SOMAXCONN

public static final int SOMAXCONN

The SOMAXCONN value of the current machine. If failed to get the value, 200 is used as a default value for Windows or 128 for others.

Method Detail

isIpV4StackPreferred

public static boolean isIpV4StackPreferred()

Returns true if ipv4 should be prefered on a system that supports ipv4 and ipv6.

createByteArrayFromIpAddressString

public static byte[] createByteArrayFromIpAddressString(String ipAddressString)

Creates an byte[] based on an ipAddressString. No error handling is performed here.

intToIpAddress

public static String intToIpAddress(int i)

Converts a 32-bit integer into an IPv4 address.

bytesToIpAddress

public static String bytesToIpAddress(byte[] bytes,
                      int offset,
                      int length)

Converts 4-byte or 16-byte data into an IPv4 or IPv6 string respectively.

Throws:

IllegalArgumentException - if length is not 4 nor 16

isValidIpV6Address

public static boolean isValidIpV6Address(String ipAddress)

isValidIpV4Address

public static boolean isValidIpV4Address(String value)

Takes a string and parses it to see if it is a valid IPV4 address.

Returns:

true, if the string represents an IPV4 address in dotted notation, false otherwise

getByName

public static Inet6Address getByName(CharSequence ip)

Returns the Inet6Address representation of a CharSequence IP address.

This method will treat all IPv4 type addresses as "IPv4 mapped" (see getByName(CharSequence, boolean))

Parameters:

ip - CharSequence IP address to be converted to a Inet6Address

Returns:

Inet6Address representation of the ip or null if not a valid IP address.

getByName

public static Inet6Address getByName(CharSequence ip,
                     boolean ipv4Mapped)

Returns the Inet6Address representation of a CharSequence IP address.

The ipv4Mapped parameter specifies how IPv4 addresses should be treated. "IPv4 mapped" format as defined in rfc 4291 section 2 is supported.

Parameters:

ip - CharSequence IP address to be converted to a Inet6Address

ipv4Mapped -

• true To allow IPv4 mapped inputs to be translated into Inet6Address
• false Don't turn IPv4 addressed to mapped addresses

Returns:

Inet6Address representation of the ip or null if not a valid IP address.

toAddressString

public static String toAddressString(InetAddress ip)

Returns the String representation of an InetAddress.

• Inet4Address results are identical to InetAddress.getHostAddress()
• Inet6Address results adhere to rfc 5952 section 4

The output does not include Scope ID.

Parameters:

ip - InetAddress to be converted to an address string

Returns:

String containing the text-formatted IP address

toAddressString

public static String toAddressString(InetAddress ip,
                     boolean ipv4Mapped)

Returns the String representation of an InetAddress.

• Inet4Address results are identical to InetAddress.getHostAddress()
• Inet6Address results adhere to rfc 5952 section 4 if ipv4Mapped is false. If ipv4Mapped is true then "IPv4 mapped" format from rfc 4291 section 2 will be supported. The compressed result will always obey the compression rules defined in rfc 5952 section 4

The output does not include Scope ID.

Parameters:

ip - InetAddress to be converted to an address string

ipv4Mapped -

• true to stray from strict rfc 5952 and support the "IPv4 mapped" format defined in rfc 4291 section 2 while still following the updated guidelines in rfc 5952 section 4
• false to strictly follow rfc 5952

Returns:

String containing the text-formatted IP address