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

According to: http://www.w3schools.com/tags/ref_urlencode.asp

"The ASCII device control characters %00-%1f were originally designed to control hardware devices. Control characters have nothing to do inside a URL."

A vendor software has a bug that actually interprets %00-%1f and does some fateful things on the system as a result. I have the vendor software behind the LTM, and want to close the TCP connection for all URLs with these ASCII codes, particularly "%00".

What is the best approach to do this? I tried the below block of code, but the request with "%00" in the URI is not being caught in the IF statement.

when HTTP_REQUEST {
    if { [HTTP::uri] contains "%00" }{
        HTTP::close
        TCP::close
    }
}