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 renetcode
  • The transport layer can be customizable. The default transport can be disabled and replaced with a custom one

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