jwt_example.go

package main

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

	"github.com/dgrijalva/jwt-go"
)

const mySigningKey = `super_secret`

var users = map[string]string{
	"aidan": "coyle",
	"foo":   "bar",
	"test":  "test",
}

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/login", login)
	mux.HandleFunc("/", root)

	log.Fatal(http.ListenAndServe(":8080", mux))
}

func login(w http.ResponseWriter, r *http.Request) {
	username := r.URL.Query().Get("username")
	password := r.URL.Query().Get("password")

	log.Println("Password: ", password)
	log.Println("Found: ", users[username])

	if password != users[username] {
		w.WriteHeader(401)
		return
	}

	claims := &jwt.StandardClaims{
		ExpiresAt: time.Now().Add(10 * time.Minute).Unix(),
		Issuer:    "doble",
		Subject:   username,
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	ss, err := token.SignedString([]byte(mySigningKey))
	if err != nil {
		panic(err)
	}

	w.Write([]byte(ss))
}

func root(w http.ResponseWriter, r *http.Request) {
	auth := r.Header.Get("Authorization")
	if auth == "" {
		w.WriteHeader(401)
		return
	}

	splits := strings.Split(auth, "Bearer ")
	if len(splits) > 2 {
		w.WriteHeader(401)
		return
	}

	tokenString := splits[1]
	token, err := jwt.ParseWithClaims(tokenString, &jwt.StandardClaims{}, func(token *jwt.Token) (interface{}, error) {
		return []byte(mySigningKey), nil
	})

	if !token.Valid || err != nil {
		w.WriteHeader(401)
		return
	}

	claims, ok := token.Claims.(*jwt.StandardClaims)
	if !ok {
		log.Fatal("lolwut")
	}

	w.Write([]byte(fmt.Sprintf("Logged in: %s", claims.Subject)))
}