dump all headers in php

headers.php

<?php

if (!function_exists('getallheaders'))  {
    function getallheaders()
    {
        if (!is_array($_SERVER)) {
            return array();
        }

        $headers = array();
        foreach ($_SERVER as $name => $value) {
            if (substr($name, 0, 5) == 'HTTP_') {
                $headers[str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($name, 5)))))] = $value;
            }
        }
        return $headers;
    }
}

$headers =  getallheaders();
foreach($headers as $key=>$val){
  echo $key . ': ' . $val . '<br>';
}
?>