php - Is $_SERVER['REQUEST_SCHEME'] reliable?

Question

I recently was seeking a way to properly determine protocol, under which url request was supplied to the server.

I watched through parse_url() and though $_SERVER superglobal variable, and found this:

<?php

header('Content-Type: text/plain');

print_r($_SERVER);

Output:

[REQUEST_SCHEME] => http

However, I was unable to find it on php.net or Google. Though, I was able to find this question. Q#1: If $_SERVER['REQUEST_SCHEME'] wasn't documented, then it is probably unreliable, or it can be trusted?

I'am using VC9 PHP 5.4.14 TS under windows for development. But my production is under ubuntu. Q#2: Is this property also availible under ubuntu linux too?

Answer 1

The REQUEST_SCHEME environment variable is documented on the Apache mod_rewrite page. However, it didn't become available until Apache 2.4.

I only have Apache 2.2 so I created an environment variable. I added the following to the top of my .htaccess file.

RewriteEngine on

# Set REQUEST_SCHEME (standard environment variable in Apache 2.4)
RewriteCond %{HTTPS} off
RewriteRule .* - [E=REQUEST_SCHEME:http]

RewriteCond %{HTTPS} on
RewriteRule .* - [E=REQUEST_SCHEME:https]

Now I can use

• %{ENV:REQUEST_SCHEME} in other rewrite conditions and rules
• $_SERVER['REQUEST_SCHEME'] in my PHP code

I don't have to do extra messy conditional checks everywhere, and my PHP code is forward compatible. When Apache is upgraded, I can change my .htaccess file.

I don't know how you'd apply this to a Windows environment. This is probably not a good solution for distributed code, but it works well for my needs.