htaccess regex to match all parts of HTTP_HOST - regex

Question

If you want to read my question without the explanation, skip to the big bold header below.
Ok folks, here we go. First, the code I have:
AddType text/x-server-parsed-html .html .htm
RewriteEngine On
RewriteBase /
# checking to see if it's a secure request, then set environment var "secure" to either "s" or ""
#
RewriteCond %{SERVER_PORT}s ^(443(s)|[0-9]+s)$ [NC]
RewriteRule ^(.+)$ - [env=secure:%2] [NC]
# Gets the value of the subdomain and puts it into environment variable "sub"
#
RewriteCond %{HTTP_HOST} ^([^\.]*)(\.)?example.com [NC]
RewriteRule ^(.*)$ - [env=sub:%1] [NC]
# Determines if the sub domain is blank, w, or ww, then redirects w/301 to www...
#
RewriteCond %{ENV:sub} ^(w|ww|)$
RewriteRule ^(.*)$ http%{ENV:secure}://www.example.com/$1 [R=301,L]
# Gets the highest sub domain and adds it as a top subdirectory to each request
#
RewriteCond %{REQUEST_URI}:example/%{ENV:sub} !^/([^/]+)[^:]*:\1 [NC]
RewriteRule ^(.*)$ /example/%{ENV:sub}/$1 [L]
#ErrorDocument 404 /pagenotfound
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?url=$1&%{QUERY_STRING} [PT]
So, everything works exactly as desired as it is, except I have to set the domain explicitly, I can't figure out the regex to get it so it will work the same with different domains. Here's how it works:
It first determines if the request is secure, and saves that for later.
Next, it does a 301 redirect for a request to example.com that either has "w","ww" or "" as a subdomain to www.example.com, thus forcing all requests for the site to use www.example.com, unless you are specifying a sub domain other than (w|ww|www), like "test" or "dev" or whatever is set up.
Next, it gets the value of the subdomain (which will always be present, because you've either requested something like "dev.example.com" or it has been redirected to "www.example.com"), and rewrites (not redirects) the request to a subdirectory two levels down. As this is set up, this would be the "www" directory under "example" in the root.
Lastly it rewrites (not redirects) the URI to be pretty, no problem there, it's working how I like it.
The directory structure is as follows: in the root, there is a directory for every site hosted here (example, anothersite, thirdsite). They are all completely unrelated for the purposes of this htaccess file. Within each directory, there are at least two directories, "www" and "dev". The production site files are in "www" and the development files are in "dev". One could also have a directory here of "test" for a testing environment, or whatever else you wanted, this is just how I'm setting it up.
So, what I want is something like:
Rewritecond %{HTTP_HOST} ^(match sub domain).(match domain).(match TLD) [NC]
RewriteRule ^(.*)$ -[env=sub:%1,env=domain:%2,env=tld:%3] [NC]
I know that line two of this works correctly, it's just the regex of line one I can't figure out. Keep in mind, there may or may not be a sub domain specified, and there may or may not be a period preceding the domain.
This would allow the entire script to handle any of the sites hosted in the root directory as described by allowing me to rewrite line 23 like:
RewriteRule ^(.*)$ http%{ENV:secure}://www.%{ENV:domain}.%{ENV:tld}/$1 [R=301,L]
And line 29 like:
RewriteCond %{REQUEST_URI}:%{ENV:domain}/%{ENV:sub} !^/([^/]+)[^:]*:\1 [NC]
So, I think I've very clearly explained what I have, what I'm trying to do, and what I hope to achieve. Can anyone help with the regex for line 15?

Answer 1

I know that line two of this works correctly, it's just the regex of line one I can't figure out. Keep in mind, there may or may not be a sub domain specified, and there may or may not be a period preceding the domain.
Your regex will look something like this:
Rewritecond %{HTTP_HOST} ^(([^\.]+)\.)?([^\.]+)\.([^\.]+)$ [NC]
RewriteRule ^(.*)$ - [env=sub:%2,env=domain:%3,env=tld:%4]
Which will change the rule line as well (you were missing a space after the "-"), because %1 now backreferences the dot as well.