从url向设备GCM发送推送消息

我发现了一个很棒的代码，它通过GCM发送推送消息。问题是，如果有可能改变字符串"谷歌云消息工作良好"

地址栏的例子我会写www.example.com/index.php?text=work

和字符串将工作。

感谢

<?php
define("GOOGLE_API_KEY", "AIzaSyCJiVkatisdQ44rEM353PFGbia29mBVscA");
define("GOOGLE_GCM_URL", "https://android.googleapis.com/gcm/send");
function send_gcm_notify($reg_id, $message) {
    $fields = array(
        'registration_ids'  => array( $reg_id ),
        'data'              => array( "message" => $message ),
    );
    $headers = array(
        'Authorization: key=' . GOOGLE_API_KEY,
        'Content-Type: application/json'
    );
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, GOOGLE_GCM_URL);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));
    $result = curl_exec($ch);
    if ($result === FALSE) {
        die('Problem occurred: ' . curl_error($ch));
    }
    curl_close($ch);
    echo $result;
}
$reg_id = "APA91bHuSGES.....nn5pWrrSz0dV63pg";
$msg = "Google Cloud Messaging working well";
send_gcm_notify($reg_id, $msg);

filter_input (INPUT_GET, 'text', FILTER_SANITIZE_STRING);