Sanity check for Github Webhook

github_webhook.php

<?php

//Github sanity check                                                                                                                          
$secret = 'my_secret_entered_on_webhook_settings_page';
$headers = getallheaders();
$hubSignature = $headers['X-Hub-Signature'];
list($algo, $hash) = explode('=', $hubSignature, 2);
$payload = file_get_contents('php://input');
$data    = json_decode($payload);
$payloadHash = hash_hmac($algo, $payload, $secret);

if ($hash !== $payloadHash) {
  die('Bad secret');
}

/** If its a release hook then you will have release.
if (isset($data->release)) {
  echo $data->release->tag_name;
  echo $data->release->zipball_url;
}