Overview

cidr-calc is a small javascript library for converting IP range to CIDRs or CIDR to IP range.

API

The API consists of three classes: IpAddress, Cidr and IpRange.

import { Cidr, IpAddress, IpRange } from 'cidr-calc';

IpAddress

An IpAddress class represents an IP address. Its instance functions are:

toByteArray: returns a copy of the byte array representing the IP address
next: return the next IP address
prev: return the previous IP address
compareTo: returns the result (-1, 0, or 1) that it compares to another IpAddress
           Only IpAddresses of the same version can be compared
toString: return the string representation of the IP address
version: returns a string '4' or '6'
regularNotation: returns a regular string representation of the IP address
                 e.g., 10.0.1.2, 2001:0:0:f:f00:0:0:1
shortNotation: returns a compact string representation of the IP address
               e.g., 10.0.1.2, 2001::f:f00:0:0:1
fullNotation: returns a full string representation of the IP address
              e.g., 010.000.001.002, 2001:0000:0000:000f:0f00:0000:0000:0001

It also has two static functions:

of: parses a string into an IpAddress
fromByteArray: constructs an IpAddress from a byte array

The implementation of the of function was inspired by the InetAddresses class in guava, Google core libraries for Java.

Cidr

A Cidr class can be constructed with an IP address and a prefix length.

let cidr = new Cidr(IpAddress.of('192.168.0.0'), 16);

Then we can convert the CIDR to an IP range with the toIpRange function.

let ipRange = cidr.toIpRange(); // 192.168.0.0 - 192.168.255.255

Note that the IP address passed in to construct the CIDR may not be the start IP of the range.

IpRange

An IpRange class can be constructed with a start IP address and an end IP address.

let ipRange = new IpRange(IpAddress.of('3::'), IpAddress.of('7:ffff:ffff:ffff:ffff:ffff:ffff:ffff'));

Then we can convert the IP range to a list of CIDRs (as a Cidr array) with the toCidrs function.

let cidrs = ipRange.toCidrs(); // [3::/16, 4::/14]

The implementation of the toCidrs function was inspired by the IPv4Range and IPv6Range classes in ineter, a fast Java library for working with IP addresses, ranges, and subnets.