iRule to block access to all but certain URIs

Create a Data Group (called uri_allow below) with the list of
permitted URI's (make sure they start with /)

when HTTP_REQUEST {
 if { not [class match [string tolower [HTTP::uri]] equals uri_allow] } {
  HTTP::respond 200 content "URL Blocked"
  Stop processing the iRule for this event here
  Return
 }
}