$req = HTTP::Request->new("CONNECT", "http://proxy1_host:proxy1_port/proxy2_host:proxy2_port",
HTTP::Headers->new(),
"GET http://final_destination.example.com/ HTTP/1.0\cJ\cM\cJ\cM");

##</code><code>##

CONNECT proxy2_host:proxy2_port HTTP/1.1
TE: deflate,gzip;q=0.3
Connection: TE, close
Host: proxy2_host:proxy2_port
User-Agent: libwww-perl/5.68
Content-Length: 39

GET http://final_destination.example.com/ HTTP/1.0

HTTP/1.0 200 Connection established