Module net 

Online play: host a game or join one over the internet or the local network. Available as ctx.net.

One player (or a dedicated server, see Engine::run_server) hosts, the others join. Everyone sends Packets: a kind and a few values. What arrives shows up as NetEvents for one frame, like key presses.

use audio_code::prelude::*;

fn main() -> audio_code::Result<()> {
    audio_code::run("Chat", |ctx| {
        if ctx.once("start") {
            ctx.net.set_name("Anna");
            ctx.net.join("localhost"); // or: ctx.net.host(net::DEFAULT_PORT)
        }
        for player in ctx.net.joined() {
            ctx.speak(format!("Connected to {}", ctx.net.name(player)));
        }
        if ctx.pressed(Key::Space) {
            ctx.net.send_all(Packet::new("chat").with("Hello!"));
        }
        for (from, packet) in ctx.net.received("chat") {
            ctx.speak(format!("{}: {}", ctx.net.name(from), packet.text(0)));
        }
        for (_, reason) in ctx.net.left() {
            ctx.speak(ctx.lang.describe_reason(&reason));
        }
    })
}

What the engine does for you

• Connecting, the handshake and all sending and receiving run on background threads. The game never waits for the network.
• Only clients of the same game (the Engine title) and the same version (Net::set_version) get in. Others are turned away with Reason::WrongGame / Reason::WrongVersion.
• Both sides ping each other every second (Net::ping). A connection that hears nothing for 10 seconds is closed with Reason::TimedOut.
• Packets arrive complete, unchanged and in the order they were sent.
• Mistakes do not crash: sending while offline does nothing, joining a wrong address ends with a NetEvent::Disconnected that says why.

WebSockets and encryption

Connections are WebSockets, so they pass firewalls and web proxies that only let web traffic through, and a server can sit behind a web server such as nginx or Caddy. Net::join takes plain addresses ("example.com", "10.0.0.2:7777") as well as ws:// and wss:// URLs.

Everything is always encrypted, without any setup: both sides make fresh keys for every connection (X25519) and encrypt every message (XChaCha20-Poly1305). Nobody who listens in can read names, chat or game data, and changed messages are detected. This does not prove who the server is, though: someone who can redirect the traffic could pose as it. To rule that out, put the server behind a web server with a real TLS certificate and join with wss:// (feature tls, on by default).

Structs

Net

The network connection: ctx.net. See the module docs.

Packet

One message between players: a kind (what it is about) and a list of values.

PeerId

A connected player. On a client the server is PeerId::SERVER.

Enums

Arg

One value inside a Packet. Made automatically by Packet::with from numbers, bool, text, Vec2, Vec3, PeerId and byte vectors.

NetEvent

Something that happened on the network this frame.

Reason

Why a connection ended. Speak it with ctx.lang.describe_reason(&reason).

Constants

DEFAULT_PORT

The port used when none is given: ctx.net.join("example.com") connects to it.