Replace part of HTTP::host and permanently redirect

Either (this is probably more efficient);

when HTTP_REQUEST {
    if {[HTTP::host] ends_with ".olddomain.com"} {
        HTTP::respond 301 Location "https://[getfield [HTTP::host] . 1].newdomain.com[HTTP::uri]"
       }
}

Or;-

when HTTP_REQUEST {
    if {[HTTP::host] ends_with ".olddomain.com"} {
        HTTP::respond 301 Location "https://[string map {olddomain newdomain} [HTTP::host]][HTTP::uri]"
       }
}