Potential way to prefix a path to a response by injecting an extra layer into the ResponseWriter

sdrw.go

type SubDirResponseWriter struct {
  ResponseWriter
  path string
}

func (w *SubDirResponseWriter) WriteHeader(code int) {
  if code/100 == 3 {
    loc := w.Header().Get("Location")
    if len(loc) > 0 {
      url := http.ParseURLReference(loc)
      url.Path = w.path + "/" + url.Path
      w.Header().Set("Location", url.String())
    }
  }
  w.ResponseWriter.WriteHeader(code)
}