[오승석] firebase를 통한 guset로그인시 email에 @guest.flag 추가

core/service.go

@@ -660,6 +660,9 @@ func (sh *serviceDescription) authorize(w http.ResponseWriter, r *http.Request)
 			}
 
 			if authtype != newType || uid != newId {
+				if authtype == "firebase" && newType == "guest" {
+					email = fmt.Sprintf("%s@guest.flag", uid)
+				}
 				authtype = newType
 				uid = newId
 			}