// Session tokens are not allowed in STS AssumeRole requests.
	if getSessionToken(r) != "" {
		return auth.Credentials{}, ErrAccessDenied
	}

	return user, ErrNone
}

func parseForm(r *http.Request) error {
	if err := r.ParseForm(); err != nil {
		return err
	}
	for k, v := range r.PostForm {
		if _, ok := r.Form[k]; !ok {
			r.Form[k] = v
		}
	}
	return nil
}