mod_rewrite: Make rules apply to both subdomains and subfolders - apache

Question

Metadata
My server setup
A shared host with wildcard subdomains and optional preceding www.
I can't touch httpd.conf and have limited .htaccess directives, although RewriteRule and the likes apply.
I use per-directory .htaccess files.
My server layout
Most subfolders (read: some are for gfx and such) are standalone applications, f.ex: A URL shortener, a image upload site.
Usual PHP controller setup
To manipulate applications, f.ex. view a specific file that's been uploaded, I read the $_SERVER['QUERY_STRING'] in order to use URIs like http://s.domain.com/?image.jpg to retrieve it from where it's stored.
This setup may differ from application to application.
Problem
What I have
Examples
URL Shortener:
http://s.domain.com/?xy7r OR http://www.domain.com/s/?xy7r retrieves the hash from a database and redirects the user.
Image Uploader:
http://d.domain.com/?xy7r.png OR http://www.domain.com/d/?xy7r.png redirects to http://d.domain.com/u/xy7r.png
(Note: the www. is optional in all cases)
What I want
Adjust my existing applications to use Apache's mod_rewrite.
Examples
URL Shortener:
http://s.domain.com/xy7r OR http://www.domain.com/s/xy7r
Image Uploader:
http://d.domain.com/xy7r.png OR http://www.domain.com/d/xy7r.png
My approach
At first I was adding RewriteRules like a happy hacker and everything worked fine,
I then noticed that as they were designed for URIs like http://sub.domain.com they did not work for
URIs like http://www.domain.com/sub.
I decided to try and set up conditions so that the rules would work for both URI cases.
So I Google-FUd and read specifications, documentations and tutorials. I do not fully understand this directive but neither do I think I found any appropriate solutions nor similar problems on the net.
I then gave up and thought I'd instead redirect the second URI syntax (http://www.domain.com/sub/) to the preferred one (http://sub.domain.com) (Also http://www.sub.domain.com), to then apply my existing RewriteRule's
My .htaccess so far
(Only for the URL Shortener as I have not moved on until I get it working)
RewriteEngine On
RewriteCond %{HTTP_HOST} !^s\.domain\.com$ [NC] # Exclude correct URI
RewriteCond %{HTTP_HOST} !^$ # Exclude old HTTP requests
RewriteCond %{REQUEST_URI} ^/s($|/.*$) # Rewrite bad URI
RewriteRule ^.* http://s.domain.com/$1 [R=permanent] # Redirect to correct URI
RewriteCond %{REQUEST_URI} !^/fonts/ # Exclude system folder
RewriteCond %{REQUEST_URI} !^/index.php # Exclude system file
RewriteCond %{REQUEST_URI} !^/style.css # -||-
RewriteCond %{REQUEST_URI} !^/script.js # -||-
RewriteCond %{REQUEST_URI} !^/short.php # -||-
RewriteRule ^(.+)$ http://s.domain.com/?$1 # Rewrite to actual URI
What I get
URI's like http://s.domain.com/xy7r work, as do the same preceded by www., but
the http://www.domain.com/s/xy7r URI syntax just redirects to http://s.domain.com and ignores the xy7r part.
Question
Am I on the right track or is there a better/more correct way to do this?
I've been trying to understand the RewriteBase directive but I don't understand it at all, and trying values like RewriteBase /s/ or s or /s don't satisfy.
In any way I am at a fullstop, I do not know how to proceed.
Any help is appreciated!
Thank you!
</WOT>

Answer 1

For the first set of rules, replace
RewriteCond %{REQUEST_URI} ^/s($|/.*$) # Rewrite bad URI
RewriteRule ^.* http://s.domain.com/$1 [R=permanent] # Redirect to correct URI
with
RewriteRule ^s/?(.*) http://s.domain.com/$1 [L,R=302]