如何获取完整的HTTP请求(非响应)头

我有这样一个简单的代码:

use LWP::UserAgent;
use HTTP::Cookies;
use HTTP::Request;

my $cookies = HTTP::Cookies->new();
my $browser = LWP::UserAgent->new();
   $browser->agent(' ... ');    
   $browser->cookie_jar($cookies);   
my $request = HTTP::Request->new();     
my $response;                           
my $url;                                
my $referer;                                        

$referer = '';
$url = 'https:// ...'; # url #1
$request->url($url);
$request->method('GET');
$request->header('Referer' => $referer);    
$response = $browser->request($request);    
print $response->request()->uri()     . "\n\n" .
      $response->headers()->as_string . "\n\n" .
      $response->content              . "\n\n";

$referer = $response->request()->uri();
$url = 'https:// ... '; # url #2
$request->url($url);
$request->method('GET');
$request->header('Referer' => $referer);
$response = $browser->request($request);
print $response->request()->uri()     . "\n\n" .
      $response->headers()->as_string . "\n\n" .
      $response->content              . "\n\n";

现在,我想查看完整的HTTP 请求报头 此外,不仅仅是响应头。

我该怎么做?此代码中必须添加哪些内容?