tessl/npm-ip

IP address utilities for node.js providing IPv4/IPv6 address manipulation, validation, and network operations

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Overview

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Files

Address Validation

Name: tessl/npm-ip
Author: tessl

Functions for validating IP address formats and classifying addresses as private, public, or loopback with support for both IPv4 and IPv6 addresses.

Capabilities

Format Validation

isV4Format

Checks if a string is in valid IPv4 format using regex validation.

/**
 * Checks if string is valid IPv4 format
 * @param {string} ip - IP address string to validate
 * @returns {boolean} True if valid IPv4 format, false otherwise
 */
function isV4Format(ip);

Usage Examples:

const ip = require('ip');

console.log(ip.isV4Format('127.0.0.1')); // true
console.log(ip.isV4Format('192.168.1.1')); // true
console.log(ip.isV4Format('255.255.255.255')); // true
console.log(ip.isV4Format('256.1.1.1')); // false (invalid octet)
console.log(ip.isV4Format('::1')); // false (IPv6)
console.log(ip.isV4Format('not-an-ip')); // false

isV6Format

Checks if a string is in valid IPv6 format using regex validation.

/**
 * Checks if string is valid IPv6 format
 * @param {string} ip - IP address string to validate  
 * @returns {boolean} True if valid IPv6 format, false otherwise
 */
function isV6Format(ip);

Usage Examples:

const ip = require('ip');

console.log(ip.isV6Format('::1')); // true
console.log(ip.isV6Format('::ffff:127.0.0.1')); // true (IPv4-mapped)
console.log(ip.isV6Format('2001:db8::1')); // true
console.log(ip.isV6Format('fe80::1')); // true
console.log(ip.isV6Format('127.0.0.1')); // false (IPv4)
console.log(ip.isV6Format('invalid')); // false

Address Comparison

isEqual

Compares two IP addresses for equality, supporting IPv4, IPv6, and mixed comparisons with IPv6-mapped IPv4 addresses.

/**
 * Compares two IP addresses for equality
 * @param {string} a - First IP address
 * @param {string} b - Second IP address  
 * @returns {boolean} True if addresses are equal, false otherwise
 */
function isEqual(a, b);

Usage Examples:

const ip = require('ip');

// IPv4 comparisons
console.log(ip.isEqual('127.0.0.1', '127.0.0.1')); // true
console.log(ip.isEqual('127.0.0.1', '127.0.0.2')); // false

// IPv6 comparisons
console.log(ip.isEqual('::1', '::1')); // true
console.log(ip.isEqual('::1', '::2')); // false

// Mixed IPv4/IPv6 comparisons (IPv6-mapped IPv4)
console.log(ip.isEqual('127.0.0.1', '::ffff:127.0.0.1')); // true
console.log(ip.isEqual('127.0.0.1', '::7f00:1')); // true
console.log(ip.isEqual('127.0.0.1', '::ffaf:7f00:1')); // false

Address Classification

isPrivate

Checks if an IP address is in a private address range, including loopback addresses.

/**
 * Checks if IP address is in private range
 * @param {string} addr - IP address to check
 * @returns {boolean} True if address is private, false otherwise
 * @throws {Error} Throws error for invalid IPv4 address
 */
function isPrivate(addr);

Supported Private Ranges:

IPv4: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16 (link-local)
IPv6: fc00::/7 (unique local), fe80::/10 (link-local)
Loopback: 127.0.0.0/8 (IPv4), ::1, fe80::1 (IPv6)

Usage Examples:

const ip = require('ip');

// IPv4 private ranges
console.log(ip.isPrivate('10.0.0.1')); // true (10.x.x.x)
console.log(ip.isPrivate('172.16.0.1')); // true (172.16-31.x.x)
console.log(ip.isPrivate('192.168.1.1')); // true (192.168.x.x)
console.log(ip.isPrivate('169.254.1.1')); // true (link-local)
console.log(ip.isPrivate('127.0.0.1')); // true (loopback)

// IPv4 public addresses
console.log(ip.isPrivate('8.8.8.8')); // false
console.log(ip.isPrivate('1.1.1.1')); // false

// IPv6 addresses
console.log(ip.isPrivate('::1')); // true (loopback)
console.log(ip.isPrivate('fe80::1')); // true (link-local)
console.log(ip.isPrivate('fd12:3456:789a:1::1')); // true (unique local)

// IPv6-mapped IPv4
console.log(ip.isPrivate('::ffff:192.168.1.1')); // true

// Special formats (hex, octal)
console.log(ip.isPrivate('0x7f.1')); // true (127.0.0.1 in hex)

isPublic

Checks if an IP address is public (not private). This is the logical inverse of isPrivate.

/**
 * Checks if IP address is public (not private)
 * @param {string} addr - IP address to check
 * @returns {boolean} True if address is public, false otherwise
 */
function isPublic(addr);

Usage Examples:

const ip = require('ip');

console.log(ip.isPublic('8.8.8.8')); // true
console.log(ip.isPublic('1.1.1.1')); // true
console.log(ip.isPublic('192.168.1.1')); // false (private)
console.log(ip.isPublic('127.0.0.1')); // false (loopback)

isLoopback

Checks if an IP address is a loopback address, supporting various input formats including decimal, octal, hexadecimal, and long integer representations.

/**
 * Checks if IP address is loopback address
 * @param {string} addr - IP address to check (supports various formats)
 * @returns {boolean} True if address is loopback, false otherwise
 */
function isLoopback(addr);

Supported Loopback Ranges:

IPv4: 127.0.0.0/8 (any address starting with 127)
IPv6: ::1, fe80::1, ::

Usage Examples:

const ip = require('ip');

// Standard IPv4 loopback
console.log(ip.isLoopback('127.0.0.1')); // true
console.log(ip.isLoopback('127.8.8.8')); // true (any 127.x.x.x)

// IPv6 loopback
console.log(ip.isLoopback('::1')); // true
console.log(ip.isLoopback('fe80::1')); // true
console.log(ip.isLoopback('::')); // true

// Various IPv4 formats
console.log(ip.isLoopback('0177.0.0.1')); // true (octal)
console.log(ip.isLoopback('0x7f.0.0.1')); // true (hex)
console.log(ip.isLoopback('2130706433')); // true (long integer)

// Non-loopback addresses
console.log(ip.isLoopback('8.8.8.8')); // false
console.log(ip.isLoopback('192.168.1.1')); // false