How to check authentication for hundreds and thousands of API endpoints? - api

Question

I am currently building a web application in golang (with Gorilla) and have implemented a handful of API endpoints. However, I noticed that every time I implement a function like
func CreateUserHandler(w http.ResponseWriter, r *http.Request) {}
I have to add the function below to the body of handler functions to check if request is authorized:
func checkAuthorizedUser (r * http.Request) error {
uid, err := CheckRequestUser (r.Cookie("uid"))
if err != nil {
return errors.New("Can't find cookie value for uid")
}
if !IsValidUser (uid.Value) {
return errors.New("Not a valid user")
}
return nil
}
What happens to me right now is that I have to add checkAuthorizedUser() to every handler function, and I have already have a lot of handler functions so far. I wonder if there is a better way to check whether a client is authorized to access certain endpoint other than explicitly checking authentication in every handler function.

Answer 1

Gorilla has a router you can use. You can then wrap the router with authentication checking. Something like this would work:
func checkPermissions(h http.Handler) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
authCheck := true //implement the actual checking
if authCheck {
w.WriteError(w, 400, "error")
return
}
h.ServeHttp(w, r)
}
}
func main() {
r := mux.NewRouter()
r.HandleFunc("/", HomeHandler)
r.HandleFunc("/products", ProductsHandler)
r.HandleFunc("/articles", ArticlesHandler)
http.Handle("/", checkPermissions(r))
}
Supporting links:
https://godoc.org/github.com/gorilla/mux#NewRouter
https://github.com/gorilla/mux