refactor code

src/client/src/tscSql.c

@@ -91,7 +91,7 @@ static SSqlObj *taosConnectImpl(const char *ip, const char *user, const char *pa
     if (tscSetMgmtEpSetFromCfg(tsFirst, tsSecond, &corMgmtEpSet) < 0) return NULL;
   }
   char rpcKey[512] = {0};
-  sprintf(rpcKey, "%s:%s:%s:%d", user, pass, ip, port);
+  snprintf(rpcKey, sizeof(rpcKey), "%s:%s:%s:%d", user, pass, ip, port);
  
   void *pRpcObj = NULL;
   if (tscAcquireRpc(rpcKey, user, secretEncrypt,&corMgmtEpSet, &pRpcObj) != 0) {

src/client/src/tscSystem.c

@@ -109,6 +109,7 @@ int32_t tscAcquireRpc(const char *key, const char *user, const char *secretEncry
   if (pRpcObj->tscCorMgmtEpSet == NULL) {
     rpcClose(rpcObj.pDnodeConn);
     pthread_mutex_unlock(&rpcObjMutex);
+    return -1;
   }
   memcpy(pRpcObj->tscCorMgmtEpSet, corMgmtEpSet, sizeof(*corMgmtEpSet));