Laravel Middleware to Validate Twilio Webhook IP

ValidateTwilioEventWebhook.php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;
use Symfony\Component\HttpFoundation\Response;

class ValidateTwilioEventWebhook
{
    public function handle(Request $request, Closure $next): Response
    {
        if (! $this->ipWithinRange($request->ip(), config('twilio.webhook_cidr'))) {
            return response('Forbidden', 403);
        }
        
        return $next($request);
    }

    private function ipWithinRange($ip, $cidr): bool
    {
        [$subnet, $mask] = explode('/', $cidr);

        $ip = inet_pton($ip);
        $subnet = inet_pton($subnet);
        $bitmask = str_repeat("\xFF", $mask >> 3);
        $bitmask .= chr((0xFF << (8 - ($mask & 7))) & 0xFF);
        $bitmask = str_pad($bitmask, 16, "\0");

        return ($ip & $bitmask) === ($subnet & $bitmask);
    }
}