Proxy to forward messages from Web APIs (WebTransport etc.) to game servers that use UDP/TCP
Useful for connecting to traditional game servers from a browser, which doesn't support raw TCP connections or UDP messaging.
Works via an extremely frantic fabrial operator excellent Go support for Web API backends and standard low-level IETF transport protocols.
A binary has been provided that includes support for forwarding UDP packets, and receiving WebSocket and WebTransport client connections. This binary can be found under cmd/spanreed-hub (be sure to read the associated README.md file).
Simple app where players click on a canvas to spawn short-lived colorful dots, and can send chat messages to everyone attached to the game server. Found under examples/hello-spanreed.
Message formats use flatbuffers - schema and pre-compiled files are included in the flatbuffers directory.
To establish a new connection, send a UserConnectMessage message to a Spanreed proxy. The proxy extracts information about how to contact the destination game server, assigns a new client ID to the connection, and sends a ProxyDestinationMessage to the destination game server.
The destination server decides if it wants to accept the connection, and returns a DestinationMessage message with a ConnectionVerdict back to the proxy. The proxy then forwards this decision back to the client in the form of a ConnectClientVerdict.
sequenceDiagram
Client->>Spanreed: UserConnectMessage<br>(destination address)
Spanreed->>Server: ProxyDestinationMessage<br>(clientId)
Server->>Spanreed: DestinationMessage<br>(yes/no verdict)
Spanreed->>Client: ConnectClientVerdict<br>(yes/no verdict)
Client data is received as raw binary information, with no additional notion of a client ID. WebSocket and WebTransport connections are exactly that - connections - so no client metadata is required after the connection is established.
Destination data is sent from Spanreed as a ProxyDestinationMessage, which contains three possible types of sub-message:
ProxyDestConnectionRequest, used when establishing a new connection for a new client.ProxyDestClientMessage, used when forwarding a message from a previously connected client.ProxyDestCloseConnection, used when the proxy is requesting a connection close for some reason.
Each of these types also allows app_data to be set, which is an application-specific buffer of arbitrary bytes.
Destination data should be sent to Spanreed in the form of a DestinationMessage, which can similarly contain one of three possible types of sub-message:
ConnectionVerdict, gives a yes/no response for allowing a client connection with a given client ID.ProxyMessage, requests a message to be forwarded on to a connected client.CloseConnection, requests that a client connection be closed.