helper.go

func (cv *CustomValidator) Validate(i interface{}) error {
	if err := cv.validator.Struct(i); err != nil {
		// Optionally, you could return the error to give each route more control over the status code
		return echo.NewHTTPError(http.StatusBadRequest, err.Error())
	}
	return nil
}

func validateUser(sl validator.StructLevel) {
	if len(sl.Current().Interface().(User).Username) == 0 || len(sl.Current().Interface().(User).Password) == 0 {
		sl.ReportError(sl.Current().Interface(), "User", "", "", "")
	}
}

func computeSecretHash(clientSecret string, username string, clientId string) string {
	mac := hmac.New(sha256.New, []byte(clientSecret))
	mac.Write([]byte(username + clientId))

	return base64.StdEncoding.EncodeToString(mac.Sum(nil))
}