HORIZON PROJECT

# ipaddr.js — an IPv6 and IPv4 address manipulation library [![Build Status](https://travis-ci.org/whitequark/ipaddr.js.svg)](https://travis-ci.org/whitequark/ipaddr.js)

ipaddr.js is a small (1.9K minified and gzipped) library for manipulating

IP addresses in JavaScript environments. It runs on both CommonJS runtimes

(e.g. [nodejs]) and in a web browser.

ipaddr.js allows you to verify and parse string representation of an IP

address, match it against a CIDR range or range list, determine if it falls

into some reserved ranges (examples include loopback and private ranges),

and convert between IPv4 and IPv4-mapped IPv6 addresses.

[nodejs]: http://nodejs.org

## Installation

`npm install ipaddr.js`

or

`bower install ipaddr.js`

## API

ipaddr.js defines one object in the global scope: `ipaddr`. In CommonJS,

it is exported from the module:

```js

var ipaddr = require('ipaddr.js');

```

The API consists of several global methods and two classes: ipaddr.IPv6 and ipaddr.IPv4.

### Global methods

There are three global methods defined: `ipaddr.isValid`, `ipaddr.parse` and

`ipaddr.process`. All of them receive a string as a single parameter.

The `ipaddr.isValid` method returns `true` if the address is a valid IPv4 or

IPv6 address, and `false` otherwise. It does not throw any exceptions.

The `ipaddr.parse` method returns an object representing the IP address,

or throws an `Error` if the passed string is not a valid representation of an

IP address.

The `ipaddr.process` method works just like the `ipaddr.parse` one, but it

automatically converts IPv4-mapped IPv6 addresses to their IPv4 counterparts

before returning. It is useful when you have a Node.js instance listening

on an IPv6 socket, and the `net.ivp6.bindv6only` sysctl parameter (or its

equivalent on non-Linux OS) is set to 0. In this case, you can accept IPv4

connections on your IPv6-only socket, but the remote address will be mangled.

Use `ipaddr.process` method to automatically demangle it.

### Object representation

Parsing methods return an object which descends from `ipaddr.IPv6` or

`ipaddr.IPv4`. These objects share some properties, but most of them differ.

#### Shared properties

One can determine the type of address by calling `addr.kind()`. It will return

either `"ipv6"` or `"ipv4"`.

An address can be converted back to its string representation with `addr.toString()`.

Note that this method:

 * does not return the original string used to create the object (in fact, there is

   no way of getting that string)

 * returns a compact representation (when it is applicable)

A `match(range, bits)` method can be used to check if the address falls into a

certain CIDR range.

Note that an address can be (obviously) matched only against an address of the same type.

For example:

```js

var addr = ipaddr.parse("2001:db8:1234::1");

var range = ipaddr.parse("2001:db8::");

addr.match(range, 32); // => true

```

Alternatively, `match` can also be called as `match([range, bits])`. In this way,

it can be used together with the `parseCIDR(string)` method, which parses an IP

address together with a CIDR range.

For example:

```js

var addr = ipaddr.parse("2001:db8:1234::1");

addr.match(ipaddr.parseCIDR("2001:db8::/32")); // => true

```

A `range()` method returns one of predefined names for several special ranges defined

by IP protocols. The exact names (and their respective CIDR ranges) can be looked up

in the source: [IPv6 ranges] and [IPv4 ranges]. Some common ones include `"unicast"`

(the default one) and `"reserved"`.

You can match against your own range list by using

`ipaddr.subnetMatch(address, rangeList, defaultName)` method. It can work with a mix of IPv6 or IPv4 addresses, and accepts a name-to-subnet map as the range list. For example:

```js

var rangeList = {

  documentationOnly: [ ipaddr.parse('2001:db8::'), 32 ],

  tunnelProviders: [

    [ ipaddr.parse('2001:470::'), 32 ], // he.net

    [ ipaddr.parse('2001:5c0::'), 32 ]  // freenet6

  ]

};

ipaddr.subnetMatch(ipaddr.parse('2001:470:8:66::1'), rangeList, 'unknown'); // => "tunnelProviders"

```

The addresses can be converted to their byte representation with `toByteArray()`.

(Actually, JavaScript mostly does not know about byte buffers. They are emulated with

arrays of numbers, each in range of 0..255.)

```js

var bytes = ipaddr.parse('2a00:1450:8007::68').toByteArray(); // ipv6.google.com

bytes // => [42, 0x00, 0x14, 0x50, 0x80, 0x07, 0x00, <zeroes...>, 0x00, 0x68 ]

```

The `ipaddr.IPv4` and `ipaddr.IPv6` objects have some methods defined, too. All of them

have the same interface for both protocols, and are similar to global methods.

`ipaddr.IPvX.isValid(string)` can be used to check if the string is a valid address

for particular protocol, and `ipaddr.IPvX.parse(string)` is the error-throwing parser.

`ipaddr.IPvX.isValid(string)` uses the same format for parsing as the POSIX `inet_ntoa` function, which accepts unusual formats like `0xc0.168.1.1` or `0x10000000`. The function `ipaddr.IPv4.isValidFourPartDecimal(string)` validates the IPv4 address and also ensures that it is written in four-part decimal format.

[IPv6 ranges]: https://github.com/whitequark/ipaddr.js/blob/master/src/ipaddr.coffee#L186

[IPv4 ranges]: https://github.com/whitequark/ipaddr.js/blob/master/src/ipaddr.coffee#L71

#### IPv6 properties

Sometimes you will want to convert IPv6 not to a compact string representation (with

the `::` substitution); the `toNormalizedString()` method will return an address where

all zeroes are explicit.

For example:

```js

var addr = ipaddr.parse("2001:0db8::0001");

addr.toString(); // => "2001:db8::1"

addr.toNormalizedString(); // => "2001:db8:0:0:0:0:0:1"

```

The `isIPv4MappedAddress()` method will return `true` if this address is an IPv4-mapped

one, and `toIPv4Address()` will return an IPv4 object address.

To access the underlying binary representation of the address, use `addr.parts`.

```js

var addr = ipaddr.parse("2001:db8:10::1234:DEAD");

addr.parts // => [0x2001, 0xdb8, 0x10, 0, 0, 0, 0x1234, 0xdead]

```

A IPv6 zone index can be accessed via `addr.zoneId`:

```js

var addr = ipaddr.parse("2001:db8::%eth0");

addr.zoneId // => 'eth0'

```

#### IPv4 properties

`toIPv4MappedAddress()` will return a corresponding IPv4-mapped IPv6 address.

To access the underlying representation of the address, use `addr.octets`.

```js

var addr = ipaddr.parse("192.168.1.1");

addr.octets // => [192, 168, 1, 1]

```

`prefixLengthFromSubnetMask()` will return a CIDR prefix length for a valid IPv4 netmask or

false if the netmask is not valid.

```js

ipaddr.IPv4.parse('255.255.255.240').prefixLengthFromSubnetMask() == 28

ipaddr.IPv4.parse('255.192.164.0').prefixLengthFromSubnetMask()  == null

```

`subnetMaskFromPrefixLength()` will return an IPv4 netmask for a valid CIDR prefix length.

```js

ipaddr.IPv4.subnetMaskFromPrefixLength(24) == "255.255.255.0"

ipaddr.IPv4.subnetMaskFromPrefixLength(29) == "255.255.255.248"

```

`broadcastAddressFromCIDR()` will return the broadcast address for a given IPv4 interface and netmask in CIDR notation.

```js

ipaddr.IPv4.broadcastAddressFromCIDR("172.0.0.1/24") == "172.0.0.255"

```

`networkAddressFromCIDR()` will return the network address for a given IPv4 interface and netmask in CIDR notation.

```js

ipaddr.IPv4.networkAddressFromCIDR("172.0.0.1/24") == "172.0.0.0"

```

#### Conversion

IPv4 and IPv6 can be converted bidirectionally to and from network byte order (MSB) byte arrays.

The `fromByteArray()` method will take an array and create an appropriate IPv4 or IPv6 object

if the input satisfies the requirements. For IPv4 it has to be an array of four 8-bit values,

while for IPv6 it has to be an array of sixteen 8-bit values.

For example:

```js

var addr = ipaddr.fromByteArray([0x7f, 0, 0, 1]);

addr.toString(); // => "127.0.0.1"

```

or

```js

var addr = ipaddr.fromByteArray([0x20, 1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1])

addr.toString(); // => "2001:db8::1"

```

Both objects also offer a `toByteArray()` method, which returns an array in network byte order (MSB).

For example:

```js

var addr = ipaddr.parse("127.0.0.1");

addr.toByteArray(); // => [0x7f, 0, 0, 1]

```

or

```js

var addr = ipaddr.parse("2001:db8::1");

addr.toByteArray(); // => [0x20, 1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]

```