server.go

package main

import (
	"net/http"
	"time"

	jwt "github.com/dgrijalva/jwt-go"
	"github.com/labstack/echo"
	"github.com/labstack/echo/middleware"
)

// jwtCustomClaims are custom claims extending default ones.
type jwtCustomClaims struct {
	Name  string `json:"name"`
	Admin bool   `json:"admin"`
	jwt.StandardClaims
}

func login(c echo.Context) error {
	username := c.FormValue("username")
	password := c.FormValue("password")

	if username == "jon" && password == "shhh!" {

		// Set custom claims
		claims := &jwtCustomClaims{
			"Jon Snow",
			true,
			jwt.StandardClaims{
				ExpiresAt: time.Now().Add(time.Hour * 72).Unix(),
			},
		}

		// Create token with claims
		token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)

		// Generate encoded token and send it as response.
		t, err := token.SignedString([]byte("secret"))
		if err != nil {
			return err
		}
		return c.JSON(http.StatusOK, map[string]string{
			"token": t,
		})
	}

	return echo.ErrUnauthorized
}

func accessible(c echo.Context) error {
	return c.String(http.StatusOK, "Accessible")
}

func restricted(c echo.Context) error {
	user := c.Get("user").(*jwt.Token)
	claims := user.Claims.(*jwtCustomClaims)
	name := claims.Name
	return c.String(http.StatusOK, "Welcome "+name+"!")
}

func main() {
	e := echo.New()

	// Middleware
	e.Use(middleware.Logger())
	e.Use(middleware.Recover())

	// Login route
	e.POST("/login", login)

	// Unauthenticated route
	e.GET("/", accessible)

	// Restricted group
	r := e.Group("/restricted")

	// Configure middleware with the custom claims type
	config := middleware.JWTConfig{
		Claims:     &jwtCustomClaims{},
		SigningKey: []byte("secret"),
	}
	r.Use(middleware.JWTWithConfig(config))
	r.GET("", restricted)

	e.Logger.Fatal(e.Start(":1323"))
}