Matching ASCII codes %00 - %1f in HTTP::uri

I am not an expert-level iRuler at this point (yet), so someone may have a better, more direct answer, but... I would add the "log" lines below. The output will show in the "Local Traffic" log (or /var/log/ltm on the F5 itself). It will give you a better idea of what is going on.

I did find a package that is supposed to "test iRules" but it isn't quite very intuitive (from what I have seen so far).

when HTTP_REQUEST {
    log local0. "Checking URI: [HTTP::uri]"
    if { [HTTP::uri] contains "%00" } {
        log local0. "Illegal URI: Closing Connection."
        HTTP::close
        TCP::close
    }
}