Take a look at LWP, along with the associated HTTP::Request, HTTP::Response, and HTTP::Headers object

use LWP;
use HTTP::Request;

my $ua = LWP::UserAgent->new();

my $request = HTTP::Request->new( GET => 'http://www.google.com' );
my $response = $ua->request( $request );
my $headers =  $response->headers();
print $headers->header( 'Content-Length');
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