web-auth-methods

A Web application for implementing JWT, HMAC and OAUTH2 functionalities

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ResponseWriter

I implement a response writer that you can give it an interface{} which type of it can be string , struct{} , *struct{} then with package reflect in golang function write response in appropriate format and HTTP header.

// dResponseWriter use for writing response to the user
func dResponseWriter(w http.ResponseWriter, data interface{}, HStat int) error {
   dataType := reflect.TypeOf(data)
   if dataType.Kind() == reflect.String {
   	w.WriteHeader(HStat)
   	w.Header().Set("Content-Type", "application/text")

   	_, err := w.Write([]byte(data.(string)))
   	return err
   } else if reflect.PtrTo(dataType).Kind() == dataType.Kind() {
   	w.WriteHeader(HStat)
   	w.Header().Set("Content-Type", "application/json")

   	outData, err := json.MarshalIndent(data, "", "\t")
   	if err != nil {
   		log.Println(err.Error())
   		w.Write([]byte(err.Error()))
   		return err
   	}

   	_, err = w.Write(outData)
   	return err
   } else if reflect.Struct == dataType.Kind() {
   	w.WriteHeader(HStat)
   	w.Header().Set("Content-Type", "application/json")

   	outData, err := json.MarshalIndent(data, "", "\t")
   	if err != nil {
   		log.Println(err.Error())
   		w.Write([]byte(err.Error()))
   		return err
   	}

   	_, err = w.Write(outData)
   	return err
   }

   return errors.New("we could not be able to support data type that you passed")
}

HMAC Signing Methods

I use a database model for saving and getting any request data and hmac token associate with it known as DataModel in repo pkg.

• I use a helper function for creating a unique key based on their own emails.
• I use two function for saving and getting HMAC token from session that stores in browser.
• You can find Everything About saving/getting or signing in the following peace of codes.

// keyGeneratorByEmail a helper function for creating unique keys based on users emails
func keyGeneratorByEmail(mail string) string {
	key := uuid.FromBytesOrNil([]byte(mail))

	return key.String()
}

// SaveHmacToken use for saving HMAC token based on sha hash functions for user
func (conf *AppConf) SaveHmacToken(w http.ResponseWriter, r *http.Request) {
	var user *repo.DataModel = &repo.DataModel{}
	err := json.NewDecoder(r.Body).Decode(&user)
	if err != nil {
		log.Println(err.Error())
		http.Error(w, "Error in parsing the body; "+err.Error(), http.StatusInternalServerError)
		return
	}
	user.Key = keyGeneratorByEmail(user.Mail)
	signToken, err := conf.SignWithHmac(user.Mail, user.Key)
	if err != nil {
		http.Error(w, err.Error()+"; in signing with hmac", http.StatusInternalServerError)
		return
	}

	conf.ScsManager.Put(r.Context(), "hmac-token", signToken)
	conf.ScsManager.Put(r.Context(), "user-mail", user.Mail)
	return
}

// GetAndCheckHmacToken use for getting and checking the HMAC token that we store it in cookies
func (conf *AppConf) GetAndCheckHmacToken(w http.ResponseWriter, r *http.Request) {
	userEmail, ok := conf.ScsManager.Get(r.Context(), "user-mail").(string)
	if !ok {
		http.Error(w, "Something went wrong; ", http.StatusInternalServerError)
		return
	}

	hmacToken, ok := conf.ScsManager.Get(r.Context(), "hmac-token").(string)
	if !ok {
		http.Error(w, "Something went wrong; ", http.StatusInternalServerError)
		return
	}

	user := &repo.DataModel{
		ID:        0,
		Mail:      userEmail,
		HmacToken: hmacToken,
	}

	err := dResponseWriter(w, user, http.StatusOK)
	if err != nil {
		log.Println(err.Error())
		return
	}

	return
}