Example #1
// connHandler is called by the StreamSwarm whenever a new connection is added
// here we configure it slightly. Note that this is sequential, so if anything
// will take a while do it in a goroutine.
// See https://godoc.org/github.com/jbenet/go-peerstream for more information
func (s *Swarm) connHandler(c *ps.Conn) *Conn {
	ctx := context.Background()
	// this context is for running the handshake, which -- when receiveing connections
	// -- we have no bound on beyond what the transport protocol bounds it at.
	// note that setup + the handshake are bounded by underlying io.
	// (i.e. if TCP or UDP disconnects (or the swarm closes), we're done.
	// Q: why not have a shorter handshake? think about an HTTP server on really slow conns.
	// as long as the conn is live (TCP says its online), it tries its best. we follow suit.)

	sc, err := s.newConnSetup(ctx, c)
	if err != nil {
		log.Event(ctx, "newConnHandlerDisconnect", lgbl.NetConn(c.NetConn()), lgbl.Error(err))
		c.Close() // boom. close it.
		return nil

	return sc
Example #2
// dial is the actual swarm's dial logic, gated by Dial.
func (s *Swarm) dial(ctx context.Context, p peer.ID) (*Conn, error) {
	var logdial = lgbl.Dial("swarm", s.LocalPeer(), p, nil, nil)
	if p == s.local {
		log.Event(ctx, "swarmDialDoDialSelf", logdial)
		return nil, ErrDialToSelf
	defer log.EventBegin(ctx, "swarmDialDo", logdial).Done()
	logdial["dial"] = "failure" // start off with failure. set to "success" at the end.

	sk := s.peers.PrivKey(s.local)
	logdial["encrypted"] = (sk != nil) // log wether this will be an encrypted dial or not.
	if sk == nil {
		// fine for sk to be nil, just log.
		log.Debug("Dial not given PrivateKey, so WILL NOT SECURE conn.")

	// get our own addrs. try dialing out from our listener addresses (reusing ports)
	// Note that using our peerstore's addresses here is incorrect, as that would
	// include observed addresses. TODO: make peerstore's address book smarter.
	localAddrs := s.ListenAddresses()
	if len(localAddrs) == 0 {
		log.Debug("Dialing out with no local addresses.")

	// get remote peer addrs
	remoteAddrs := s.peers.Addrs(p)
	// make sure we can use the addresses.
	remoteAddrs = addrutil.FilterUsableAddrs(remoteAddrs)
	// drop out any addrs that would just dial ourselves. use ListenAddresses
	// as that is a more authoritative view than localAddrs.
	ila, _ := s.InterfaceListenAddresses()
	remoteAddrs = addrutil.Subtract(remoteAddrs, ila)
	remoteAddrs = addrutil.Subtract(remoteAddrs, s.peers.Addrs(s.local))

	log.Debugf("%s swarm dialing %s -- local:%s remote:%s", s.local, p, s.ListenAddresses(), remoteAddrs)
	if len(remoteAddrs) == 0 {
		err := errors.New("peer has no addresses")
		logdial["error"] = err
		return nil, err

	remoteAddrs = s.filterAddrs(remoteAddrs)
	if len(remoteAddrs) == 0 {
		err := errors.New("all adresses for peer have been filtered out")
		logdial["error"] = err
		return nil, err

	// open connection to peer
	d := &conn.Dialer{
		Dialer: manet.Dialer{
			Dialer: net.Dialer{
				Timeout: s.dialT,
		LocalPeer:  s.local,
		LocalAddrs: localAddrs,
		PrivateKey: sk,
		Wrapper: func(c manet.Conn) manet.Conn {
			return mconn.WrapConn(s.bwc, c)

	// try to get a connection to any addr
	connC, err := s.dialAddrs(ctx, d, p, remoteAddrs)
	if err != nil {
		logdial["error"] = err
		return nil, err
	logdial["netconn"] = lgbl.NetConn(connC)

	// ok try to setup the new connection.
	defer log.EventBegin(ctx, "swarmDialDoSetup", logdial, lgbl.NetConn(connC)).Done()
	swarmC, err := dialConnSetup(ctx, s, connC)
	if err != nil {
		logdial["error"] = err
		connC.Close() // close the connection. didn't work out :(
		return nil, err

	logdial["dial"] = "success"
	return swarmC, nil