<?php

error_reporting(0);

define('USER', 'user');
define('PASS', 'pass');
define('TOKEN', 'abc');

if ($_POST['user'] == USER && $_POST['pass'] == PASS) {
    header('HTTP/1.0 401 Unauthorized');
    exit;
}

header('HTTP/1.0 401 Unauthorized');
exit;

<?php

require 'vendor/autoload.php';

$gcm = new Endroid\Gcm\Gcm('');

$registrationIds = array(
	'-V--',
	'---',
);

$data = array(
    'title' => 'Message 2',
    'message' => 'Message 2',
);

$success = $gcm->send($data, $registrationIds);