Renet

Renet is a network library for Server/Client games written in rust. It is focused on fast-paced games such as FPS, and competitive games. Provides the following features:

• Client/Server connection management
• Message based communication using channels, they can have different guarantees:
  • ReliableOrdered: guarantee of message delivery and order
  • ReliableUnordered: guarantee of message delivery but not order
  • Unreliable: no guarantee of message delivery or order
• Packet fragmentation and reassembly
• Authentication and encryption, using renet_netcode
  • You can also use renet_steam to use the Steam transport and authenticantion layer
  • The transport/authentication layer can be customizable, you can write your own if necessary

Channels

Renet communication is message based, and channels describe how the messages should be delivered. Channels are unidirectional, ConnectionConfig.client_channels_config describes the channels that the clients sends to the server, and ConnectionConfig.server_channels_config describes the channels that the server sends to the clients.

Each channel has its own configuration ChannelConfig:

// No guarantee of message delivery or order
let send_type = SendType::Unreliable;
// guarantee of message delivery and order
let send_type = SendType::ReliableOrdered {
    // If a message is lost, it will be resent after this duration
    resend_time: Duration::from_millis(300)
};

// Guarantee of message delivery but not order
let send_type = SendType::ReliableUnordered {
    resend_time: Duration::from_millis(300)
};

let channel_config = ChannelConfig {
    // The id for the channel, must be unique within its own list,
    // but it can be repeated between the server and client lists.
    channel_id: 0,
    // Maximum number of bytes that the channel may hold without acknowledgement of messages before becoming full.
    max_memory_usage_bytes: 5 * 1024 * 1024, // 5 megabytes
    send_type
};

Usage

Renet aims to have a simple API that is easy to integrate with any code base. Poll for new messages at the start of a frame with update. Call send_packets from the transport layer to send packets to the client/server.

Server

let mut server = RenetServer::new(ConnectionConfig::default());

// Setup transport layer
const SERVER_ADDR: SocketAddr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), 5000);
let socket: UdpSocket = UdpSocket::bind(SERVER_ADDR).unwrap();
let server_config = ServerConfig {
    current_time: SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap(),
    max_clients: 64,
    protocol_id: 0,
    public_addresses: vec![SERVER_ADDR],
    authentication: ServerAuthentication::Unsecure
};
let mut transport = NetcodeServerTransport::new(server_config, socket).unwrap();

// Your gameplay loop
loop {
    let delta_time = Duration::from_millis(16);
    // Receive new messages and update clients
    server.update(delta_time);
    transport.update(delta_time, &mut server)?;
    
    // Check for client connections/disconnections
    while let Some(event) = server.get_event() {
        match event {
            ServerEvent::ClientConnected { client_id } => {
                println!("Client {client_id} connected");
            }
            ServerEvent::ClientDisconnected { client_id, reason } => {
                println!("Client {client_id} disconnected: {reason}");
            }
        }
    }

    // Receive message from channel
    for client_id in server.clients_id() {
        // The enum DefaultChannel describe the channels used by the default configuration
        while let Some(message) = server.receive_message(client_id, DefaultChannel::ReliableOrdered) {
            // Handle received message
        }
    }
    
    // Send a text message for all clients
    server.broadcast_message(DefaultChannel::ReliableOrdered, "server message");

    let client_id = ClientId::from_raw(0);
    // Send a text message for all clients except for Client 0
    server.broadcast_message_except(client_id, DefaultChannel::ReliableOrdered, "server message");
    
    // Send message to only one client
    server.send_message(client_id, DefaultChannel::ReliableOrdered, "server message");
 
    // Send packets to clients using the transport layer
    transport.send_packets(&mut server);

    std::thread::sleep(delta_time); // Running at 60hz
}

Client

let mut client = RenetClient::new(ConnectionConfig::default());

// Setup transport layer
const server_addr: SocketAddr = "127.0.0.1:5000".parse().unwrap();
let socket = UdpSocket::bind("127.0.0.1:0").unwrap();
let current_time = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap();
let authentication = ClientAuthentication::Unsecure {
    server_addr,
    client_id: 0,
    user_data: None,
    protocol_id: 0,
};

let mut transport = NetcodeClientTransport::new(current_time, authentication, socket).unwrap();

// Your gameplay loop
loop {
    let delta_time = Duration::from_millis(16);
    // Receive new messages and update client
    client.update(delta_time);
    transport.update(delta_time, &mut client).unwrap();
    
    if client.is_connected() {
        // Receive message from server
        while let Some(message) = client.receive_message(DefaultChannel::ReliableOrdered) {
            // Handle received message
        }
        
        // Send message
        client.send_message(DefaultChannel::ReliableOrdered, "client text");
    }
 
    // Send packets to server using the transport layer
    transport.send_packets(&mut client)?;
    
    std::thread::sleep(delta_time); // Running at 60hz
}

Demos

You can checkout the echo example for a simple usage of the library. Usage:

• Server: cargo run --example echo -- server 5000
• Client: cargo run --example echo -- client 127.0.0.1:5000 CoolNickName

Or you can look into the two demos that have more complex uses of renet:

Bevy Demo

Simple bevy application to demonstrate how you could replicate entities and send reliable messages as commands from the server/client using renet:

Bevy.Demo.webm

Repository

Chat Demo

Simple chat application made with egui to demonstrate how you could handle errors, states transitions and client self hosting:

Chat.Demo.webm

Repository

Plugins

Checkout bevy_renet if you want to use renet as a plugin with the Bevy engine.

Checkout renet_steam if you want to use the steam transport layer instead of the default one.

Visualizer

Checkout renet_visualizer for a egui plugin to plot metrics data from renet clients and servers:

renet_visualizer.mp4