$pu['file']
 

In robot_functions.php you make a call to parse_url($url)
and set this:
settype($pu['file'],'string');

The problem is that 'file' is not a valid component of the parse_url function and, of course, is always empty.

only these compenents ares valid:
scheme
host
port
user
pass
path
query
fragment

So, what is supposed to be 'file', 'query' ?

I forgot to say in which function:
function phpdigGetSiteFromUrl($id_connect,$url)

[Edit:]
Ok, I think that I see what is wrong.
The call to phpdigRewriteUrl should be:
$subpu = phpdigRewriteUrl($pu['path'].$pu['query'].$pu['fragment']);

At least, that's how I understand what you're doing in that function.

If you'd like to know more about the function phpdigGetSiteFromUrl, you can read about it in the documentation here.

Hope it helps. :)