GCM Implementation using PHP always facing Unauthorized Error 401

Question

I am always getting 401 error.Please any one could let me know exactly what should be HTTP referrers if i am using my local server. i.e Currently I am using:

    http://localhost/GCM/index.php 

and generating a API access key using it.

Here is my php code for GCM request.

                $key='mykey';
                $headers=array('Contenttype:application/json','Authorization:key='.$key);
                $url = 'https://android.googleapis.com/gcm/send';
                $ch = curl_init();
                $curlConfig = array(
                CURLOPT_URL            => $url,
                CURLOPT_POST           => true,
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_POSTFIELDS     => json_encode(array('field1' => 'some date','field2' => 'some other data',)),
                CURLOPT_HTTPHEADER     => $headers,
                CURLOPT_SSL_VERIFYPEER => false,
                CURLOPT_SSL_VERIFYHOST => false,
                );
                curl_setopt_array($ch, $curlConfig);
                $result = curl_exec($ch);
                curl_close($ch);
                if($result==FALSE){
                    echo curl_error($ch);
                    echo curl_getinfo($ch);
                }else{
                    echo $result;
                }

Answer 1

I battled same problem. Turned out it was IPv6 related! I created server key as described in http://developer.android.com/google/gcm/gs.html using 0.0.0.0/0 as permitted host IP, but that does not match IPv6. So I added another permitted host line IP as 0::0/0 and that worked (AFTER some time, to update cached config?).

Leaving the IP field blank allows ANY IP and is easier.