Custom Protocol Messages

If you have a mod, it might be of interest to create custom protocol messages to communicate additional information between your client and the server.

See Receiving Protocol Messages for information on actaully receiving your messages from the client. This page is just to declare them.

Message Types

As per how the Among Us protocol is structured, messages can be declared on certain levels and as children of certain parent messages. For example, messages that are identified by the first byte are called option packets, although you most likely won't be using these as they're part of Hazel itself.

With that in mind, you can declare messages by extending the relevant class:

Type	Description	Identifier	Parent message	Base class
Root	Used for reliable/unreliable messages, related to stateless communication between the client and the server.	root	ReliablePacket/UnreliablePacket	BaseRootMessage
GameData	Used for messages that are related to the game, and communicate with a little bit of state involved.	gamedata	GameDataMessage	BaseGameDataMessage
Rpc	(Remote Procedure Call) Used for messages in games that communicate directly to objects, and are heavily based on recording state.	rpc	RpcMessage	BaseRpcMessage

Message Class

Check out the SkeldJS source for full, proper examples.

Check the table above to know which base class your message class should extend.

Example

export class SayHelloMessage extends BaseRootMessage {
    static messageTag = 60 as const;
    messageTag = 60 as const;

    constructor(public readonly message: string) {
        super();
    }

    static Deserialize(reader: HazelReader) {
        const message = reader.string();
        return new MyRootMessage(message);
    }

    Serialize(writer: HazelWriter) {
        writer.string(this.message);
    }

    clone() {
        return new MyRootMessage(this.message);
    }
}

Message tag

The messageTag property should be any unused integer, as long as it's the same as the tag that the client sends. This is just used to identfiy your message and decode it when it's encountered.

The messageTag should generally be between 0-255, especially for official Among Us message types.

Note that other mods may have their own message tags, so make sure that other mods that you use don't conflict with your message tags.

Registering custom messages

Use the RegisterMessage decorator to register your custom message to be recognised by Hindenburg:

@RegisterMessage(SayHelloMessage)
@HindenburgPlugin("hbplugin-mouse-messager-plugin")
export class MouseMessagerPlugin extends WorkerPlugin {

}

Note that custom messages can only be instantiated and used on a worker plugin.

Check out Receiving Protocol Messages to learn how to handle your custom messages sent by clients.

Sending custom messages

Sending custom messages in Hindenburg is just as simple as instantiating the class, for example:

connection.sendPacket(
    new ReliablePacket(
        connection.getNextNonce(),
        [
            new SayHelloMessage("there's a mouse! where? there on the stair, right there!")
        ]
    )
);