php - methods for determining if traffic is through https or http

I need a simple function to decide if the it's using https or http. I was thinking - is there a way for php to access the port #? So if it's 443 I know 开发者_JS百科it's secure, and if it's 80 I know it's normal.

What other ways are there of determining this?

<?php 
if($_SERVER['HTTPS']){ 
  //secure 
}else{ 
  // not secure
} 
?> 

However some servers don't set HTTPS, so in the worst case:

<?php
if (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) {
  // secure
}
?>