func EchoStreamHandler(stream inet.Stream) {
	c := stream.Conn()
	log.Debugf("%s echoing %s", c.LocalPeer(), c.RemotePeer())
	go func() {
		defer stream.Close()
		io.Copy(stream, stream)
	}()
}

func EchoStreamHandler(stream inet.Stream) {
	go func() {
		defer stream.Close()

		// pull out the ipfs conn
		c := stream.Conn()
		log.Infof("%s ponging to %s", c.LocalPeer(), c.RemotePeer())

		buf := make([]byte, 4)

		for {
			if _, err := stream.Read(buf); err != nil {
				if err != io.EOF {
					log.Info("ping receive error:", err)
				}
				return
			}

			if !bytes.Equal(buf, []byte("ping")) {
				log.Infof("ping receive error: ping != %s %v", buf, buf)
				return
			}

			if _, err := stream.Write([]byte("pong")); err != nil {
				log.Info("pond send error:", err)
				return
			}
		}
	}()
}

func (ids *IDService) ResponseHandler(s inet.Stream) {
	defer s.Close()
	c := s.Conn()

	r := ggio.NewDelimitedReader(s, 2048)
	mes := pb.Identify{}
	if err := r.ReadMsg(&mes); err != nil {
		return
	}
	ids.consumeMessage(&mes, c)

	log.Debugf("%s received message from %s %s", ID,
		c.RemotePeer(), c.RemoteMultiaddr())
}

// HandleSync reads the next name off the Stream, and calls a handler function
// This is done synchronously. The handler function will return before
// HandleSync returns.
func (m *Mux) HandleSync(s inet.Stream) {
	ctx := context.Background()

	name, handler, err := m.ReadHeader(s)
	if err != nil {
		err = fmt.Errorf("protocol mux error: %s", err)
		log.Event(ctx, "muxError", lgbl.Error(err))
		s.Close()
		return
	}

	log.Debugf("muxer handle protocol %s: %s", s.Conn().RemotePeer(), name)
	handler(s)
}

// newStreamHandler is the remote-opened stream handler for inet.Network
// TODO: this feels a bit wonky
func (h *BasicHost) newStreamHandler(s inet.Stream) {
	protoID, handle, err := h.Mux().Negotiate(s)
	if err != nil {
		if err == io.EOF {
			log.Debugf("protocol EOF: %s", s.Conn().RemotePeer())
		} else {
			log.Warning("protocol mux failed: %s", err)
		}
		return
	}

	logStream := mstream.WrapStream(s, protocol.ID(protoID), h.bwc)

	go handle(logStream)
}

func (p *PingService) PingHandler(s inet.Stream) {
	buf := make([]byte, PingSize)

	for {
		_, err := io.ReadFull(s, buf)
		if err != nil {
			log.Debug(err)
			return
		}

		_, err = s.Write(buf)
		if err != nil {
			log.Debug(err)
			return
		}
	}
}

// handleStream is our own handler, which returns an error for simplicity.
func (rs *RelayService) handleStream(s inet.Stream) error {
	defer s.Close()

	// read the header (src and dst peer.IDs)
	src, dst, err := ReadHeader(s)
	if err != nil {
		return fmt.Errorf("stream with bad header: %s", err)
	}

	local := rs.host.ID()

	switch {
	case src == local:
		return fmt.Errorf("relaying from self")
	case dst == local: // it's for us! yaaay.
		log.Debugf("%s consuming stream from %s", local, src)
		return rs.consumeStream(s)
	default: // src and dst are not local. relay it.
		log.Debugf("%s relaying stream %s <--> %s", local, src, dst)
		return rs.pipeStream(src, dst, s)
	}
}

func ping(s inet.Stream) (time.Duration, error) {
	buf := make([]byte, PingSize)
	u.NewTimeSeededRand().Read(buf)

	before := time.Now()
	_, err := s.Write(buf)
	if err != nil {
		return 0, err
	}

	rbuf := make([]byte, PingSize)
	_, err = io.ReadFull(s, rbuf)
	if err != nil {
		return 0, err
	}

	if !bytes.Equal(buf, rbuf) {
		return 0, errors.New("ping packet was incorrect!")
	}

	return time.Now().Sub(before), nil
}

func (ids *IDService) RequestHandler(s inet.Stream) {
	defer s.Close()
	c := s.Conn()

	bwc := ids.Host.GetBandwidthReporter()
	s = mstream.WrapStream(s, ID, bwc)

	w := ggio.NewDelimitedWriter(s)
	mes := pb.Identify{}
	ids.populateMessage(&mes, s.Conn())
	w.WriteMsg(&mes)

	log.Debugf("%s sent message to %s %s", ID,
		c.RemotePeer(), c.RemoteMultiaddr())
}

func TestNotifications(t *testing.T) {
	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 5)
	defer func() {
		for _, s := range swarms {
			s.Close()
		}
	}()

	timeout := 5 * time.Second

	// signup notifs
	notifiees := make([]*netNotifiee, len(swarms))
	for i, swarm := range swarms {
		n := newNetNotifiee()
		swarm.Notify(n)
		notifiees[i] = n
	}

	connectSwarms(t, ctx, swarms)

	<-time.After(time.Millisecond)
	// should've gotten 5 by now.

	// test everyone got the correct connection opened calls
	for i, s := range swarms {
		n := notifiees[i]
		notifs := make(map[peer.ID][]inet.Conn)
		for j, s2 := range swarms {
			if i == j {
				continue
			}

			// this feels a little sketchy, but its probably okay
			for len(s.ConnectionsToPeer(s2.LocalPeer())) != len(notifs[s2.LocalPeer()]) {
				select {
				case c := <-n.connected:
					nfp := notifs[c.RemotePeer()]
					notifs[c.RemotePeer()] = append(nfp, c)
				case <-time.After(timeout):
					t.Fatal("timeout")
				}
			}
		}

		for p, cons := range notifs {
			expect := s.ConnectionsToPeer(p)
			if len(expect) != len(cons) {
				t.Fatal("got different number of connections")
			}

			for _, c := range cons {
				var found bool
				for _, c2 := range expect {
					if c == c2 {
						found = true
						break
					}
				}

				if !found {
					t.Fatal("connection not found!")
				}
			}
		}
	}

	complement := func(c inet.Conn) (*Swarm, *netNotifiee, *Conn) {
		for i, s := range swarms {
			for _, c2 := range s.Connections() {
				if c.LocalMultiaddr().Equal(c2.RemoteMultiaddr()) &&
					c2.LocalMultiaddr().Equal(c.RemoteMultiaddr()) {
					return s, notifiees[i], c2
				}
			}
		}
		t.Fatal("complementary conn not found", c)
		return nil, nil, nil
	}

	testOCStream := func(n *netNotifiee, s inet.Stream) {
		var s2 inet.Stream
		select {
		case s2 = <-n.openedStream:
			t.Log("got notif for opened stream")
		case <-time.After(timeout):
			t.Fatal("timeout")
		}
		if s != s2 {
			t.Fatal("got incorrect stream", s.Conn(), s2.Conn())
		}

		select {
		case s2 = <-n.closedStream:
			t.Log("got notif for closed stream")
		case <-time.After(timeout):
			t.Fatal("timeout")
		}
		if s != s2 {
			t.Fatal("got incorrect stream", s.Conn(), s2.Conn())
//.........这里部分代码省略.........

func WrapStream(base inet.Stream, pid protocol.ID, bwc metrics.Reporter) inet.Stream {
	return newMeteredStream(base, pid, base.Conn().RemotePeer(), bwc.LogRecvMessageStream, bwc.LogSentMessageStream)
}