Adding options to existing .htaccess - .htaccess

Question

I have this .htaccess code which I have put together from different sources and I am having trouble adding a couple of extra options to it.
<Limit GET POST PUT>
order deny,allow
deny from all
allow from XXX.XXX.XXX.XXX
</Limit>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f [OR]
RewriteCond %{REQUEST_FILENAME} !-d
# allow things that are certainly necessary
RewriteCond %{REQUEST_URI} "/css/" [OR]
RewriteCond %{REQUEST_URI} "/js/" [OR]
RewriteCond %{REQUEST_URI} "/images/"
RewriteRule .* - [L]
RewriteRule ^([a-zA-Z0-9-/_]+)/([a-zA-Z0-9-/_%]+)/([a-zA-Z0-9-/_]+)/([a-zA-Z0-9-/_]+)$ index.php?primary=$1&secondary=$2&tertiary=$3&quaternary=$4 [QSA]
RewriteRule ^([a-zA-Z0-9-/_]+)/([a-zA-Z0-9-/_%]+)/([a-zA-Z0-9-/_]+)$ index.php?primary=$1&secondary=$2&tertiary=$3 [QSA]
RewriteRule ^([a-zA-Z0-9-/_]+)/([a-zA-Z0-9-/_%]+)$ index.php?primary=$1&secondary=$2 [QSA]
RewriteRule ^([a-zA-Z0-9-/_]+)$ index.php?primary=$1
Firstly I would like to add the forced use of www. in the URL. When I have tried to add this, the resulting URL becomes the output of the current RewriteRules, containing the GET variables. I believe this is because the rules work on a loop?
Another thing I would like to do is catch anything that doesnt meet the criteria of the current rules and send that to something like index.php?primary=error. The way it works now is almost perfect for my use because if there is a malformed URL or illegal character, the site is not going to even attempt to display the page. The site will create all URLs safely, so any bad URLs would be the result of experimenting in the address bar, but it would be nice to have an error page rather than a page not found.
Thanks in advance.. And sorry for the muddle-through use of RewriteRule!

Answer 1

Your regex are incorrect since hyphen can be unescaped only when it appears as first or last symbol in a character class, it needs to be escaped otherwise.
So instead of: [a-zA-Z0-9-/_%]
Use: [\w%/-]
Your complete set of rules:
RewriteEngine On
RewriteBase /
# add www in the URL
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,NE,L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d [OR]
# allow things that are certainly necessary
RewriteCond %{REQUEST_URI} ^/(css|js|images)/ [NC]
RewriteRule ^ - [L]
RewriteRule ^([^/]+)/([^/]+)/([^/]+)/([^/]+)/?$ index.php?primary=$1&secondary=$2&tertiary=$3&quaternary=$4 [QSA,L]
RewriteRule ^([^/]+)/([^/]+)/([^/]+)/?$ index.php?primary=$1&secondary=$2&tertiary=$3 [QSA,L]
RewriteRule ^([^/]+)/([^/]+)/?$ index.php?primary=$1&secondary=$2 [QSA,L]
RewriteRule ^([^/]+)/?$ index.php?primary=$1 [QSA,L]