github oauth gorilla

weboauth.go

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/codegangsta/negroni"
	gh "github.com/google/go-github/github"
	"github.com/gorilla/mux"
	"github.com/gorilla/sessions"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/github"
)

var Store = sessions.NewCookieStore([]byte("f426e903c4eaf50c96b2473419d3eb70b086bd51775565573958e759192c3eb8"))

var (
	conf = &oauth2.Config{
		ClientID:     "<client-id>",
		ClientSecret: "<client-secret>",
		Scopes:       []string{"user:email"},
		Endpoint:     github.Endpoint,
	}
)

type Handler func(w http.ResponseWriter, r *http.Request)

func main() {

	r := mux.NewRouter().StrictSlash(false)
	r.HandleFunc("/", GenericHandler("Home Page"))
	r.HandleFunc("/page1", GenericHandler("Page 1"))
	r.HandleFunc("/page2", GenericHandler("Page 2"))

	api := r.PathPrefix("/auth").Subrouter()
	api.HandleFunc("/login", LoginHandler)
	api.HandleFunc("/callback", CallbackHandler)
	api.HandleFunc("/logout", LogoutHandler)

	mux1 := http.NewServeMux()
	mux1.Handle("/", negroni.New(
		negroni.HandlerFunc(AuthMiddleware),
		negroni.Wrap(r),
	))

	mux1.Handle("/auth/", negroni.New(
		negroni.HandlerFunc(LoggingMiddleware),
		negroni.Wrap(r),
	))

	n := negroni.Classic()
	n.UseHandler(mux1)
	http.ListenAndServe(":3000", n)
}

func GenericHandler(s string) Handler {
	return func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, s)
	}
}

func LoginHandler(w http.ResponseWriter, r *http.Request) {
	url := conf.AuthCodeURL("state", oauth2.AccessTypeOnline)
	http.Redirect(w, r, url, http.StatusFound)
}
func LogoutHandler(w http.ResponseWriter, r *http.Request) {
	session, _ := Store.Get(r, "authtest")
	delete(session.Values, "user")
	session.Options.MaxAge = -1
	_ = session.Save(r, w)
	w.WriteHeader(http.StatusCreated)

}

func CallbackHandler(w http.ResponseWriter, r *http.Request) {
	code := r.FormValue("code")
	log.Println("CODE:", code)

	token, err := conf.Exchange(oauth2.NoContext, code)
	if err != nil {
		log.Println("oauthConf.Exchange() failed with", err)
		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
		return
	}

	oauthClient := conf.Client(oauth2.NoContext, token)
	client := gh.NewClient(oauthClient)
	user, _, err := client.Users.Get("")

	if err != nil {
		log.Println("github user fetch failed", err)
		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
		return
	}

	session, err := Store.Get(r, "authtest")
	session.Values["user"] = *user.Login
	session.Save(r, w)
	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
}

func AuthMiddleware(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
	log.Println("AuthMiddleware")
	session, err := Store.Get(r, "authtest")

	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	log.Println(session.Values["user"])

	if session.Values["user"] == nil {
		http.Redirect(w, r, "/auth/login", 301)
	} else {
		next(w, r)
	}

}

func LoggingMiddleware(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
	log.Println("LoggingMiddleware")
	next(w, r)
}