moksha

Servers and networking

Run a game server and send messages between clients and server. Native platforms only.

Networking runs on native platforms and not yet on web, because browsers have no raw sockets. Servers build on every desktop OS, including Linux on ARM64 such as a Raspberry Pi. On a server-only machine, configure with -DMOKSHA_BUILD_CLIENT=OFF.

A game server

A server is a plain main plus your IGameServerListener:

int main(int argc, char** argv) {
    MyListener listener;
    ME::ServerApp app;
    return app.Run(argc, argv, listener);
}

Build it with:

moksha_add_server(MyGame_Server SOURCES main.cpp RES_LIST resources/res_list.json)

ServerApp handles paths, settings.ini, networking, 60 Hz time and timers, and the GameServer. GameServer runs one non-blocking UDP socket and handles up to 256 datagrams per tick. It answers the engine’s own verbs itself: connect, ping, and relaying chat and data to other clients.

The listener

  • OnStart(ServerApp&): get timers and the server here.
  • OnClientConnected: a client joined.
  • OnGameMessage(clientID, verb, reader): one of your game’s messages arrived. Reply with Send, Broadcast or SendToOthers.
  • OnEnd: clear timers and close resources.

Wire format

One datagram is u8 version | u8 verb | u8 clientID | payload, at most 1,200 bytes. Verbs 0x00-0x7F belong to the engine, and 0x80-0xFF (FIRST_GAME_VERB and up) belong to your game, which defines its own payloads. Messages are read and written with ByteWriter and ByteReader, which are bounds-checked and use caller-owned memory and native byte order. The Cookbook has a client-side example.

Limits

These matter if you’re considering it for anything beyond experiments:

  • There’s no acknowledgement or resend layer, and no authentication. The version byte isn’t checked.
  • There’s no disconnect or timeout, and client IDs are never reused, so restart the server after 255 connects.
  • A repeated connect from the same address gets a new ID, so a client that retries leaves an unused client behind.
  • There’s no SIGTERM handler, so stopping the process skips OnEnd.
  • Every datagram is logged at info level.

Hosting

Open UDP 9310, or your configured port, in the host’s firewall. resources/config/settings.ini sits next to the executable, with the port under [settings] port. Without it, the default port is used. Clients point at a server with --serverIP=<ip> and --serverPort=<port>.

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