URL character limitation

[eluser]sirtea[/eluser]
I'm trying to make a debian-packages-query type
ex: http://packages.debian.org/lxde

In my case, is something like localhost/users/search/contains/gmail

You can always search using a form that submits that value to an action that redirects to this URL, or you can put this query directly.

There's some queries that behaves anormally. Ex:
localhost/users/search/contains/@gmail
//@ not permitted in url

localhost/users/search/contains/.
//the same as localhost/users/search/contains/ -> contains "" -> everything

localhost/users/search/contains/..
// same as localhost/users/search/


I don't want to code hexadecimal values, so the user can make the query directly, but i have no other options.
¿Someone has a better idea?

[eluser]titoneo[/eluser]

Code:

$config['permitted_uri_chars'] = 'a-z 0-9~%.:_\-@';

[eluser]sirtea[/eluser]
this does not solve the /controller/search/.. case
but is a nice try, thanks
I will give a try