System.Net.Http.AuthenticateAttribute.OnAuthorization C# (CSharp) Method

        public override void OnAuthorization(HttpActionContext actionContext)
        {
            var input = actionContext.Request;
            var principal = PrincipalHelper.GetPrincipalFromHttpRequest(input);
            if (principal == null)
            {
                throw UnauthorizedException();
            }

            var user = Membership.GetUser(principal.Identity.Name);
            if (user == null)
            {
                throw UnauthorizedException();
            }

            PrincipalHelper.SetPrincipal(input, principal);
            
            base.OnAuthorization(actionContext);
        }