SID_NULL
| Protocol | BNCS |
|---|---|
| Directions | Client → Server and Server → Client |
| Used by |           
|
Keep-alive. An empty message both sides may send so an idle connection stays open.
Client → Server
Every few minutes while the connection is otherwise quiet.
No payload: the message is only its 4-byte header.
Server → Client
From time to time. The client doesn't need to reply.
No payload: the message is only its 4-byte header.
Remarks
SID_NULL is exactly the 4-byte header, FF 00 04 00. Sending it regularly lets either side notice a connection that has silently died, such as after a network drop.
Sources and credits
- BNETDocs Atlas server (MIT): message handler used to cross-check the layout
- BNETDocs, SID_NULL (client to server): documented by Kyro.
- BNETDocs, SID_NULL (server to client): documented by Kyro.
This page is written in our own words. BNETDocs is credited for its research; none of its text is copied. See Credits.