It appears that redirecting HTTP to HTTPS in Squid 2.5 is not trivial. From the squid-users archives:
Squid-2.5 has the peculiar limitation that requests accepted by https_port will internally be processed as http:// requests, meaning that http:// is sent to redirectors etc.
What you can do to differentiate http_port from https_port in squid-2.5 is to enable httpd_accel_port virtual, then look for the port number in your redirector, clean up the url etc.
Another option is to look into Squid-3.0 where this is a whole lot easier and does not require a redirector helper.
/Bart
