asp.net - WebAPI returning UnAuthorized if missing Header Value -

using aps.net mvc 4 webapi

each request must have header called "version" if doesn't or version low, need return unauthorized value client. i'm not sure how send response .

in baseapicontroller have this:

public abstract class baseapicontroller : apicontroller {      public override system.threading.tasks.task<system.net.http.httpresponsemessage> executeasync(system.web.http.controllers.httpcontrollercontext controllercontext, system.threading.cancellationtoken cancellationtoken)     {         var versiontext = controllercontext.request.headers.getvalues("version").firstordefault();         if(!string.isnullorempty(versiontext))            int.tryparse(versiontext, out _version);           ***here*** if _version <1 return unauthorized ???? ****            return base.executeasync(controllercontext, cancellationtoken);     } } 

i'm not sure if that's acceptable way of doing can try out returning task give response want:

// if version < 1

return new task<httpresponsemessage>(() =>         return request.createresponse(httpstatuscode.unauthorized));