Support binding to any port (for testing, 127.0.0.1) for acceptor

[Benjamin Sergeant]

The problem I am trying to solve is getting rid of modal dialogs on macOS about "the application is trying to run a server on port xxxx".

In torrent_start.go we have:

func (t *torrent) startAcceptor() {
	if t.acceptor != nil {
		return
	}
	listener, err := net.ListenTCP("tcp4", &net.TCPAddr{Port: t.port})
	if err != nil {
		t.log.Warningf("cannot listen port %d: %s", t.port, err)
	} else {
		t.log.Info("Listening peers on tcp://" + listener.Addr().String())
		t.port = listener.Addr().(*net.TCPAddr).Port
		t.portC <- t.port
		t.acceptor = acceptor.New(listener, t.incomingConnC, t.log)
		go t.acceptor.Run()
	}
}

If we were to pass another argument to TCPAddr we could bind to another host.

[Cenk Altı]

Implemented in bbd55e9.

[Benjamin Sergeant]

Thanks @cenkalti !