Go μTP

Go implementation of the Micro Transport Protocol.

Getting Started

First you will need a net.PacketConn. This can be anything implementing the interface. There are no abstraction-breaking checks for a particular implementation. Then use utp.NewSocket to get started.

func createSocket() *utp.Socket {
    // Create a UDP socket listening on all addresses
    pc, err := net.ListenPacket("udp", "0.0.0.0:0")
    if err != nil {
        panic(err)
    }

    // Call utp.New to create a *utp.Socket from the net.PacketConn
    s := utp.NewSocket(pc)
    return s
}

// As a server
func useAsServer(s *utp.Socket) error {
    for {
        conn, err := s.Accept()
        go func() {
            defer conn.Close()
            // handle the conn
        }
    }
}

// As a client
func useAsClient(s *utp.Socket, raddr net.Addr) error {
    conn, err := s.DialContext(ctx, raddr)
    if err != nil {
        return err
    }
    defer conn.Close
    // send some data to the other party
    _, err := conn.Write([]byte("hello world"))
    return err
}

Instrumentation

All logging and metrics are provided by the stdctx library. If you want logs or metrics just configure a context as described there, and pass it in.

Contributing

just is used to run commands.

just test runs the tests.

Contributions are welcome.

Roadmap

Long term it would be best for the implementation to change to be more testable. The Socket and Conn objects are the right API (adhearing to net.Listener/net.Dialer and net.Conn respectively), but they are difficult to test. There needs to be a state machine object, which doesn't have go routines or timers internally, so that arbitrary stimulus at arbitrary states can be tested.

Fork

Orginally forked from github.com/anacrolix/utp. There were a number of reasons for forking:

• The pure go implementation is deprecated in favor of a C-Go port of libutp. This fork will continue to be pure Go.
• The API was very UDP specifc, taking string addresses in several places.
• Legacy logging, and instrumentation.
• High quality user experience on top of INET256.