How to add content HTTP_HOST variable to query string - php

Question

i need to create a rewrite rule/condition that always rewrites the http_host to the query string.
i have multiple domains and all of them point to the same DocumentRoot.
What i want to do now is, to add the called domain-name (e.g.) example1.org to the query-string for application internal use. Let's say the application is situated at baseapplication.org
opening
example.org
in my browser runs into document root and htaccess should rewrite it internally to:
baseapplication.org?requested_domain=example1.org
i cannot find a combination of rewrite rules or conditions to get that running.

Answer 1

Im not a .HTACCESS pro, but this should do the trick.
<IfModule mod_rewrite.c>
Options +FollowSymLinks
RewriteEngine On
</IfModule>
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]
</IfModule>
have that in your root, in a file named .HTACCESS along with a index.php file.
Then in the index file you can access all the request vars.
From here you can either do a php headers redirect, or include the file from another dir.
up to you.
Not a solution, but should help a little

Answer 2

From the Apache documentation:
Description:
Assume that you want to provide www.username.host.domain.com for the homepage of username via just DNS A records to the same machine and without any virtualhosts on this machine.
Solution:
For HTTP/1.0 requests there is no solution, but for HTTP/1.1 requests which contain a Host: HTTP header we can use the following ruleset to rewrite http://www.username.host.com/anypath internally to /home/username/anypath:
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.[^.]+\.host\.com$
RewriteRule ^(.+) %{HTTP_HOST}$1 [C]
RewriteRule ^www\.([^.]+)\.host\.com(.*) /home/$1$2
There are a handful of other HTTP rewrites at the Apache Rewrite Guide.