diff --git a/core/service.go b/core/service.go
index c9e2d48..123eae2 100644
--- a/core/service.go
+++ b/core/service.go
@@ -329,6 +329,13 @@ func (sh *serviceDescription) link(w http.ResponseWriter, r *http.Request) {
 	// fmt.Println(oldAuth.Uid)
 	// fmt.Println("=================")
 
+	oldType, oldId, err := sh.getProviderInfo(oldType, oldId)
+	if err != nil {
+		logger.Error("getProviderInfo failed :", err)
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
 	//if oldAuth.Token != oldToken || oldAuth.Uid != oldId || oldAuth.Platform != oldType {
 	if oldAuth.Uid != oldId || oldAuth.Platform != oldType {
 		logger.Println("link failed. session key is not correct :", *oldAuth, queryvals)
@@ -452,6 +459,13 @@ func (sh *serviceDescription) unlink(w http.ResponseWriter, r *http.Request) {
 	// fmt.Println(authInfo.Uid)
 	// fmt.Println("=================")
 
+	sType, sId, err := sh.getProviderInfo(sType, sId)
+	if err != nil {
+		logger.Error("getProviderInfo failed :", err)
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
 	if authInfo.Uid != sId || authInfo.Platform != sType {
 		logger.Println("unlink failed. session key is not correct :", *authInfo, queryvals)
 		w.WriteHeader(http.StatusBadRequest)