Grabbing a domain name from URL as a variable by htaccess - php

Question

Imagine in my website I want to show some analytic about domains, working URL example of what I need:
http://whois.domaintools.com/google.com
As you see in the above URL, it's handling google.com as a variable and pass it to another page to process the given variable, that's exactly what I want.
So for detecting that kind of variable, here is my regex:
/^[a-zA-Z\d]+(?:-?[a-zA-Z\d])+\.[a-zA-Z]+$/
The above RegEx is simple and accepts everything like: google.com, so in my .htaccess file I have:
RewriteRule (^[a-zA-Z\d]+(?:-?[a-zA-Z\d])+\.[a-zA-Z]+$) modules/pages/page.php?domain=$1
The above rule do what I want, but it also redirects my homepage to page.php while there is nothing in the URL, forexample: http://mysitename.com is now being forwarded to page.php
How can I fix this?
Thanks in advance

Answer 1

It redirects also the base domain to page.php because of the regex. You are using the + on all places, the meaning of the plus is "Matches the preceding pattern element one or more times.". (http://en.wikipedia.org/wiki/Regular_expression) If you request the homepage, it redirects because all the elements are appearing zero times, like you defined in the regex.
Instead of the + you should define a minimum and a maximum amount of characters (so the zero occurrences are not evaluated). BTW, a quick search in google for "regex domain" will output a lot of results, which are tested. Use the following for example:
RewriteEngine on
RewriteRule (^(([a-zA-Z]{1})|([a-zA-Z]{1}[a-zA-Z]{1})|([a-zA-Z]{1}[0-9]{1})|([0-9]{1}[a-zA-Z]{1})|([a-zA-Z0-9][a-zA-Z0-9-_]{1,61}[a-zA-Z0-9]))\.([a-zA-Z]{2,6}|[a-zA-Z0-9-]{2,30}\.[a-zA-Z]{2,3})$) modules/pages/page.php?domain=$1
Reference:
Domain name validation with RegEx
Update 1:
If you want to use your own regex, exchange the last "+" with {2,}. The top-level domains have usually at least 2 characters.
RewriteEngine on
RewriteCond %{REQUEST_URI} !(\.html|\.php|\.pdf|\.gif|\.png|\.jpg|\|\.jpeg)$
RewriteRule (^[a-zA-Z\d]+(?:-?[a-zA-Z\d])+\.[a-zA-Z]{2,}$) modules/pages/page.php?domain=$1