Apache rewrite : how avoid to display url parameter when the url final slash is omitted? - url-rewriting

Question

In my .htacess of my domain, I must point subdomain to the 1rst GET parameter of the domain. The subdomain represents the language (for example en., fr, etc...).
In order to achieve this aim, here the rewrite code in the .htaccess :
Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^(.*)\.example\.com$ [NC]
RewriteRule ^(.*)$ $1?lang=%1 [NC,L]
I create a directory named test. This directory contains just index.html file.
So when you type in the url bar of a browser en.example.com/test/,
the rewrite code works.
But if you type en.example.com/test without the final slash, it redirects to en.example.com/test/?lang=en => it's a problem.
So have you an idea to correct that ?
Thank you in advance, cordially.

Answer 1

When specifying xx.example.com/test/, an internal redirect
occurs to xx.example.com/test/?lang=xx. The client never sees the ?lang=xx.
However, when specifying xx.example.com/test, where test is a directory,
mod_dir steps in and rewrites the URL to xx.example.com/test/, but in
such a way that the rewrite rule for the ?lang=xx redirect becomes public,
having the client see xx.example.com/test/?lang=xx as the URL - which is unwanted.
In order to keep the '?lang=' redirect local (hidden from the client)
place this in the .htaccess, BEFORE the original rewrite rules:
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^(.+[^/])$ $1/ [R,L]
The condition checks whether the requested filename is a directory,
and the rule forces a client-side redirect [R], so that a client requesting xx.example.com/test will be redirected to xx.example.com/test/.
The key however is the [L], which makes this rule the Last, preventing the following rules from executing. Without this L flag, the entire redirect from xx.example.com/test to xx.example.com/test/?lang=xx becomes public.
After the client is forcefully redirected to the proper URL with a terminating /, the rewrite rules doing the internal redirect adding the lang GET parameter are executed as normal.
Here's the entire .htaccess:
Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^(.+[^/])$ $1/ [R,L]
RewriteCond %{HTTP_HOST} ^(.*)\.example\.com$ [NC]
RewriteRule ^(.*)$ $1?lang=%1 [NC,L]
There is however another way to achieve this without using Apache config and internal redirect, and that is to examine $_SERVER['SERVER_NAME']:
<?php
list( $lang ) = explode('.', $_REQUEST['SERVER_NAME'] );