├── README.md
└── jwt.go


/README.md:
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 1 | ## Simple authentication example using JSON web tokens and Go 
 2 | 
 3 | #### How to run 
 4 | 
 5 | Simple fire it up with **go run jwt.go** and it's running on port 9000
 6 | 
 7 | Visit **/settoken** to get a token 
 8 | 
 9 | Visit **/profile** only if you have a valid token 
10 | 
11 | Visit **/logout** to logout if you have a vlid token
12 | 
13 | #### Uses:
14 | 
15 | * [dgrijalva/jwt-go](https://github.com/dgrijalva/jwt-go)
16 | 
17 | 


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/jwt.go:
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 1 | package main
 2 | 
 3 | import (
 4 | 	"context"
 5 | 	"fmt"
 6 | 	"net/http"
 7 | 	"time"
 8 | 
 9 | 	"github.com/dgrijalva/jwt-go"
10 | )
11 | 
12 | type Key int
13 | 
14 | const MyKey Key = 0
15 | 
16 | // JWT schema of the data it will store
17 | type Claims struct {
18 | 	Username string `json:"username"`
19 | 	jwt.StandardClaims
20 | }
21 | 
22 | // create a JWT and put in the clients cookie
23 | func setToken(res http.ResponseWriter, req *http.Request) {
24 | 	expireToken := time.Now().Add(time.Hour * 1).Unix()
25 | 	expireCookie := time.Now().Add(time.Hour * 1)
26 | 
27 | 	claims := Claims{
28 | 		"myusername",
29 | 		jwt.StandardClaims{
30 | 			ExpiresAt: expireToken,
31 | 			Issuer:    "localhost:9000",
32 | 		},
33 | 	}
34 | 
35 | 	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
36 | 
37 | 	signedToken, _ := token.SignedString([]byte("secret"))
38 | 
39 | 	cookie := http.Cookie{Name: "Auth", Value: signedToken, Expires: expireCookie, HttpOnly: true}
40 | 	http.SetCookie(res, &cookie)
41 | 
42 | 	http.Redirect(res, req, "/profile", 307)
43 | }
44 | 
45 | // middleware to protect private pages
46 | func validate(page http.HandlerFunc) http.HandlerFunc {
47 | 	return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
48 | 		cookie, err := req.Cookie("Auth")
49 | 		if err != nil {
50 | 			http.NotFound(res, req)
51 | 			return
52 | 		}
53 | 
54 | 		token, err := jwt.ParseWithClaims(cookie.Value, &Claims{}, func(token *jwt.Token) (interface{}, error) {
55 | 			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
56 | 				return nil, fmt.Errorf("Unexpected signing method")
57 | 			}
58 | 			return []byte("secret"), nil
59 | 		})
60 | 		if err != nil {
61 | 			http.NotFound(res, req)
62 | 			return
63 | 		}
64 | 
65 | 		if claims, ok := token.Claims.(*Claims); ok && token.Valid {
66 | 			ctx := context.WithValue(req.Context(), MyKey, *claims)
67 | 			page(res, req.WithContext(ctx))
68 | 		} else {
69 | 			http.NotFound(res, req)
70 | 			return
71 | 		}
72 | 	})
73 | }
74 | 
75 | // only viewable if the client has a valid token
76 | func protectedProfile(res http.ResponseWriter, req *http.Request) {
77 | 	claims, ok := req.Context().Value(MyKey).(Claims)
78 | 	if !ok {
79 | 		http.NotFound(res, req)
80 | 		return
81 | 	}
82 | 
83 | 	fmt.Fprintf(res, "Hello %s", claims.Username)
84 | }
85 | 
86 | // deletes the cookie
87 | func logout(res http.ResponseWriter, req *http.Request) {
88 | 	deleteCookie := http.Cookie{Name: "Auth", Value: "none", Expires: time.Now()}
89 | 	http.SetCookie(res, &deleteCookie)
90 | 	return
91 | }
92 | 
93 | func main() {
94 | 	http.HandleFunc("/settoken", setToken)
95 | 	http.HandleFunc("/profile", validate(protectedProfile))
96 | 	http.HandleFunc("/logout", validate(logout))
97 | 	http.ListenAndServe(":9000", nil)
98 | }
99 | 


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