1 2 3 4 5 6 7 8  1 2 3 4 5 6 7 8  1 2 3 4 5 6 7 8  1 2 3 4 5 6 7 8
+----------------+----------------+----------------+----------------+
|         server_msg len          |            data_len             |
+----------------+----------------+----------------+----------------+
|     status     |         server_msg ...
+----------------+----------------+----------------+----------------+
|     data ...
+----------------+