UdtLib 1.0.1

UdtLib

UdtLib is a managed .NET 8+ implementation of the UDT (UDP-based Data Transfer) protocol.

It provides reliable, ordered, message-oriented transport over UDP through a small async API. The package is intended for applications that want UDP as the underlying transport but still need delivery guarantees and predictable message ordering.

Why UdtLib

• Reliable delivery over UDP with retransmission on missing acknowledgements
• Ordered message processing per session
• Async-first API based on Task and IAsyncEnumerable<T>
• Server and client entry points with a minimal public surface
• Managed implementation built on System.Net.Sockets, System.Threading.Channels, and System.Buffers
• Works with both IPv4 and IPv6 through IPEndPoint

Installation

dotnet add package UdtLib

Package contents

The package exposes four main entry points:

• IUdtServer for accepting remote peers over UDP
• IUdtSession for bidirectional message exchange
• IUdtSender when only sending is needed
• IUdtReceiver when only receiving is needed

Use IUdtServer.Create(...) to bind a server socket and UdtClient.Connect(...) to create an outbound session.

Quick start

Server

using System.Net;
using UdtLib;

var endpoint = new IPEndPoint(IPAddress.Any, 9000);

await using IUdtServer server = IUdtServer.Create(endpoint);

await foreach (IUdtSession session in server.AcceptAllAsync(cancellationToken))
{
    _ = Task.Run(() => HandleSessionAsync(session, cancellationToken));
}

static async Task HandleSessionAsync(IUdtSession session, CancellationToken cancellationToken)
{
    await using (session)
    {
        await foreach (ReadOnlyMemory<byte> message in session.ReadAllAsync(cancellationToken))
        {
            await session.SendAsync(message, cancellationToken);
        }
    }
}

Client

using System.Net;
using UdtLib;

await using IUdtSession session =
    UdtClient.Connect(new IPEndPoint(IPAddress.Loopback, 9000));

byte[] payload = "Hello, UDT!"u8.ToArray();

await session.SendAsync(payload, cancellationToken);

await foreach (ReadOnlyMemory<byte> reply in session.ReadAllAsync(cancellationToken))
{
    Console.WriteLine($"Received {reply.Length} bytes");
    break;
}

API summary

IUdtServer

UdtClient

IUdtSession

IUdtSession combines IUdtSender, IUdtReceiver, and IAsyncDisposable.

Transport characteristics

• Message-oriented: each send represents one payload
• Reliable: sent frames are retransmitted until acknowledged
• Ordered: inbound messages are exposed in sequence order
• Maximum payload per frame: 65,535 bytes

UdtLib is a good fit when you want a lightweight managed UDP transport with reliability semantics, especially for message-based protocols, service-to-service communication, and controlled networking environments.

Requirements

• .NET 8
• .NET 10

License

BSD 3-Clause.

Source repository: https://github.com/yartat/udtsharp