显示PHP为HTTP请求准确的标头？

Is there a way to get the exact Headers sent by function like file_get_contents() or get_headers() ?

like

get_headers('http://google.it');
echo php_get_request_headers();  //> ?

Had this issue once so what i use is a proxy such as fiddler http://www.fiddler2.com/fiddler2/

$default_opts = array(
  'http'=>array(
    'method'=>"HEAD",
    'proxy'=>"tcp://localhost:8888"
  )
);

$default = stream_context_set_default($default_opts);
$headers = get_headers('http://google.com');

var_dump($headers);

It capture all the request sent by this script because of the stream_context_set_default .. this would work for file_get_contents , fopen etc.