[php] PHP: HTTP or HTTPS?

How can I tell if a php page was accessed via http or https?

$_SERVER['HTTPS']

This will contain a 'non-empty' value if the request was sent through HTTPS

PHP Server Variables

If your request is sent by HTTPS you will have an extra server variable named 'HTTPS'

if (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off') { //HTTPS } 

If the request was sent with HTTPS you will have a extra parameter in the $_SERVER superglobal - $_SERVER['HTTPS']. You can check if it is set or not

if( isset($_SERVER['HTTPS'] ) ) {

You should be able to do this by checking the value of $_SERVER['HTTPS'] (it should only be set when using https).

See http://php.net/manual/en/reserved.variables.server.php.

This can get more complicated depending on where PHP sits in your environment, since your question is quite broad. This may depend on whether there's a load-balancer and how it's configured. Here are are a few related questions:

• How can I prevent access to PHP files if the caller isn't using HTTPS?
• Detecting HTTPS vs HTTP on server sending back nothing useful

$protocol = strtolower(substr($_SERVER["SERVER_PROTOCOL"],0,5))=='https'?'https':'http';

$protocol = isset($_SERVER["HTTPS"]) ? 'https' : 'http';

These should both work