About

This library implements uTorrent Transport Protocol with pure Dart , no any other native library.

More uTP informations please take a look BEP 0029.

How to use

UTP socket include ServerUTPSocket and UTPSocketClient.

Listening income connection:

  var serverSocket = await ServerUTPSocket.bind(InternetAddress.anyIPv4, portyoulike);

  serverSocket.listen((socket) {
    print('someone connect me');
    socket.listen((data) {
     // receive data
    });
  });

Connect remote:

  var client = UTPSocketClient();
  var socket = await client.connect(remoteAddress, remotePort);

  socket.listen((data) {
     // receive data
  });

Each UTPSocketClient can create mulitple UTP socket via connect method and each UTP socket share the same raw UDP socket , user can set the max UTP socket number (default is 5) when create UTPSocketClient instance.

Send data:

    socket.write(sometext); // write some text
    socket.writeln(sometext); // write some text with \n
    // write mulitple text together and sperate with ','
    socket.writeAll(sometextList,',');
    socket.add(somebyteslist); // send some List<int> data

The default text encoding is UTF-8 , user can set the encoding:

   socket.encoding = someencoding;

Even UTP socket use UDP to delivery the datas , but the UTP socket won't send the data 'one-by-one' , it will add the data into sending buffer , once there is avalidate window size , the socket will read the buffer data out with the avalidate size(less than the max packet size) and packet them together to send out.

on the other hand , If the sending data methods(add,write,etc...) are invoked in the same tick , these sending datas will be added in a cache , the socket will request to send them next tick.

For example:

    socket.write('u');
    socket.write('T');
    socket.write('P');

These methods are invoke in same tick , these datas ('u','T','P') will add into a cache (become 'uTP') and will be send next tick.

But it not means that remote will receive the 'uTP' in one packet , it depends the current window size.

Receive(listening) data:

   socket.listen((Uint8List data) {
     // receive data
   },
   onDone : (){
       // when remote or local socket closed , this method will be invoke
   },
   onError:(e){
       // when error happen,invoke this method
   });

Close the socket:

  await socket.close();

When invode the close method , the socket will send ST_FIN message to remote and waiting for the ack from remote , if user want to close it immediately , you can call this method :

  socket.destroy();

Actually , destroy method will send ST_RESET message to remote ,but it won't wait the ACK.

If socket close , it will wait for the expect ACK seq number, when the correct seq number received , the close method will completed future , or it will complete the future when timeout