Retrieve the real IP address of the user making the request.

getRealUserIP.js

/**
 * Real User IP Grabber
 *
 * @author    Mohamed Riyad <m@ryad.me>
 * @link      RyadPasha.com
 * @copyright Copyright (C) 2022 RyadPasha. All rights reserved.
 * @license   GNU General Public License v3.0 http://www.gnu.org/copyleft/gpl.html
 * @version   Release: 1.0
 * @since     10 Nov, 2022
 */

/**
 * Retrieve the real IP address of the user making the request.
 * Supports various IP address sources including CloudFlare proxy,
 * `x-forwarded-for` header, `x-real-ip` header, and remote address from the socket or connection.
 *
 * @param   {Object} req - The request object representing the incoming HTTP request.
 * @returns {string} The real IP address of the user.
 * @author  Mohamed Riyad <m@ryad.me>
 * @since   10 Nov, 2022
 * @updated 12 May, 2023
 */
const getRealUserIP = (req) => {
    const headers = req.headers

    // Prefer `cf-connecting-ip` header (CloudFlare proxy)
    if (headers['cf-connecting-ip']) {
        return headers['cf-connecting-ip']
    }

    // Check `x-forwarded-for` header
    const forwardedFor = headers['x-forwarded-for']
    if (forwardedFor) {
        // The x-forwarded-for header can contain a comma-separated list of IP's.
        // Extract the first IP address.
        return forwardedFor.split(',')[0].trim()
    }

    // Check `x-real-ip` header
    if (headers['x-real-ip']) {
        return headers['x-real-ip']
    }

    // Fallback to retrieving remote address from `req.socket`
    if (req.socket && req.socket.remoteAddress) {
        return req.socket.remoteAddress
    }

    // Or from the deprecated `req.connection`
    if (req.connection && req.connection.remoteAddress) {
        return req.connection.remoteAddress
    }

    // If all else fails, return an empty string
    return ''
}

module.exports = getRealUserIP