initial commit

Author: ossan-dev

go.mod

@@ -0,0 +1,17 @@
+module golangjwt
+
+go 1.19
+
+require (
+	github.com/go-playground/validator/v10 v10.11.1
+	github.com/golang-jwt/jwt v3.2.2+incompatible
+)
+
+require (
+	github.com/go-playground/locales v0.14.0 // indirect
+	github.com/go-playground/universal-translator v0.18.0 // indirect
+	github.com/leodido/go-urn v1.2.1 // indirect
+	golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3 // indirect
+	golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069 // indirect
+	golang.org/x/text v0.3.7 // indirect
+)

go.sum

@@ -0,0 +1,51 @@
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-playground/assert/v2 v2.0.1 h1:MsBgLAaY856+nPRTKrp3/OZK38U/wa0CcBYNjji3q3A=
+github.com/go-playground/assert/v2 v2.0.1/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
+github.com/go-playground/locales v0.14.0 h1:u50s323jtVGugKlcYeyzC0etD1HifMjqmJqb8WugfUU=
+github.com/go-playground/locales v0.14.0/go.mod h1:sawfccIbzZTqEDETgFXqTho0QybSa7l++s0DH+LDiLs=
+github.com/go-playground/universal-translator v0.18.0 h1:82dyy6p4OuJq4/CByFNOn/jYrnRPArHwAcmLoJZxyho=
+github.com/go-playground/universal-translator v0.18.0/go.mod h1:UvRDBj+xPUEGrFYl+lu/H90nyDXpg0fqeB/AQUGNTVA=
+github.com/go-playground/validator/v10 v10.11.1 h1:prmOlTVv+YjZjmRmNSF3VmspqJIxJWXmqUsHwfTRRkQ=
+github.com/go-playground/validator/v10 v10.11.1/go.mod h1:i+3WkQ1FvaUjjxh1kSvIA4dMGDBiPU55YFDl0WbKdWU=
+github.com/golang-jwt/jwt v3.2.2+incompatible h1:IfV12K8xAKAnZqdXVzCZ+TOjboZ2keLg81eXfW3O+oY=
+github.com/golang-jwt/jwt v3.2.2+incompatible/go.mod h1:8pz2t5EyA70fFQQSrl6XZXzqecmYZeUEB8OUGHkxJ+I=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/leodido/go-urn v1.2.1 h1:BqpAaACuzVSgi/VLzGZIobT2z4v53pjosyNd9Yv6n/w=
+github.com/leodido/go-urn v1.2.1/go.mod h1:zt4jvISO2HfUBqxjfIshjdMTYS56ZS/qv49ictyFfxY=
+github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
+github.com/rogpeppe/go-internal v1.8.0/go.mod h1:WmiCO8CzOY8rg0OYDC4/i/2WRWAB6poM+XZ2dLUbcbE=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3 h1:0es+/5331RGQPcXlMfP+WrnIIS6dNnNRe0WB02W0F4M=
+golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
+golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069 h1:siQdpVirKtzPhKl3lZWozZraCFObP8S1v6PRp0bLrtU=
+golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

handlers/handlers.go

@@ -0,0 +1,34 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+type message struct {
+	Status string `json:"status"`
+	Info   string `json:"info"`
+}
+
+func HandlePage(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	var msg message
+	err := json.NewDecoder(r.Body).Decode(&msg)
+	if err != nil {
+		panic(err)
+	}
+	r.Body.Close()
+	err = json.NewEncoder(w).Encode(msg)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func ReservedPage(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	res := &message{Status: "private endpoint", Info: "this is a private endpoint, you must be authenticated for seeing it"}
+	err := json.NewEncoder(w).Encode(res)
+	if err != nil {
+		panic(err)
+	}
+}

handlers/login.go

@@ -0,0 +1,70 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+	"time"
+
+	"github.com/go-playground/validator/v10"
+	"github.com/golang-jwt/jwt"
+)
+
+// this key has to be kept secure. Whoever will have this key can authenticate our users
+var secretKey = []byte("Abcd1234!!")
+
+type tokenRes struct {
+	Token string `json:"token"`
+}
+
+type tokenReq struct {
+	Username string `json:"username" validate:"required"`
+	Password string `json:"password" validate:"required"`
+}
+
+func generateToken(username, password string) (string, error) {
+	// TODO: here you can add logic to check against a DB
+	//...
+
+	// create a new token by providing the cryptographic algorithm
+	token := jwt.New(jwt.SigningMethodHS256)
+
+	// set default/custom claims
+	claims := token.Claims.(jwt.MapClaims)
+	claims["exp"] = time.Now().Add(10 * time.Minute).Unix()
+	claims["username"] = username
+	claims["password"] = password
+
+	tokenString, err := token.SignedString(secretKey)
+	if err != nil {
+		return "", err
+	}
+	return tokenString, nil
+}
+
+func Login(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+
+	var req tokenReq
+	err := json.NewDecoder(r.Body).Decode(&req)
+	if err != nil {
+		panic(err)
+	}
+
+	r.Body.Close()
+
+	validator := validator.New()
+	if err = validator.Struct(&req); err != nil {
+		panic(err)
+	}
+
+	bearerToken, err := generateToken(req.Username, req.Password)
+	if err != nil {
+		panic(err)
+	}
+
+	res := &tokenRes{Token: bearerToken}
+	err = json.NewEncoder(w).Encode(res)
+	if err != nil {
+		panic(err)
+	}
+}

handlers/verify.go

@@ -0,0 +1,44 @@
+package handlers
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/golang-jwt/jwt"
+)
+
+func IsAuthorized(endpoint func(w http.ResponseWriter, r *http.Request)) http.HandlerFunc {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// check if there is the token
+		if r.Header["Authorization"] != nil {
+
+			// parse the token
+			token, err := jwt.Parse(strings.Replace(r.Header["Authorization"][0], "Bearer ", "", 1), func(token *jwt.Token) (interface{}, error) {
+				_, ok := token.Method.(*jwt.SigningMethodHMAC)
+				if !ok {
+					w.WriteHeader(http.StatusUnauthorized)
+					w.Write([]byte(fmt.Sprintf("unexpected signing method: %v", token.Header["alg"])))
+				}
+				return secretKey, nil
+			})
+			// err while parsing the token
+			if err != nil {
+				w.WriteHeader(http.StatusUnauthorized)
+				w.Write([]byte("err while parsing the jwt token!"))
+				return
+			}
+
+			// token valid
+			if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
+				fmt.Printf("username: %q\n", claims["username"])
+				fmt.Printf("password: %q\n", claims["password"])
+				endpoint(w, r)
+				return
+			}
+
+		}
+		w.WriteHeader(http.StatusUnauthorized)
+		w.Write([]byte("you must provide the jwt token!"))
+	})
+}

main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+
+	"golangjwt/handlers"
+)
+
+func main() {
+	http.HandleFunc("/home", handlers.HandlePage)
+	http.HandleFunc("/login", handlers.Login)
+	http.HandleFunc("/reserved", handlers.IsAuthorized(handlers.ReservedPage))
+	err := http.ListenAndServe(":8000", nil)
+	if err != nil {
+		panic(fmt.Sprintf("err while listening on port 8000, err: %v", err))
+	}
+}