dev servers irule

OK, I'm no expert and haven't used findstr much or had to use variables with redirect but here's my first attempt. The idea is to check for a request containing www, pull out the server number and redirect to the correct app domain/server;

when HTTP_REQUEST {
 if { [string tolower [HTTP::host]] contains ".www." } {
  set devserverid [findstr [HTTP::host] "dev" 0 "."]
  log local0. "Found $devserverid in HTTP host"
  HTTP::redirect "http://dev" + "$devsererid" + ".app.etc.com[[http:uri]]"
  }
}