make ping its own protocol

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>

protocol/ping/ping.go

+package ping
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"time"
+
+	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
+
+	host "github.com/ipfs/go-ipfs/p2p/host"
+	inet "github.com/ipfs/go-ipfs/p2p/net"
+	peer "github.com/ipfs/go-ipfs/p2p/peer"
+	eventlog "github.com/ipfs/go-ipfs/thirdparty/eventlog"
+	u "github.com/ipfs/go-ipfs/util"
+)
+
+var log = eventlog.Logger("ping")
+
+const PingSize = 32
+
+const ID = "/ipfs/ping"
+
+type PingService struct {
+	Host host.Host
+}
+
+func NewPingService(h host.Host) *PingService {
+	ps := &PingService{h}
+	h.SetStreamHandler(ID, ps.PingHandler)
+	return ps
+}
+
+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
+		}
+	}
+}
+
+func (ps *PingService) Ping(ctx context.Context, p peer.ID) (<-chan time.Duration, error) {
+	s, err := ps.Host.NewStream(ID, p)
+	if err != nil {
+		return nil, err
+	}
+
+	out := make(chan time.Duration)
+	go func() {
+		defer close(out)
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+				t, err := ping(s)
+				if err != nil {
+					log.Debugf("ping error: %s", err)
+					return
+				}
+
+				select {
+				case out <- t:
+				case <-ctx.Done():
+					return
+				}
+			}
+		}
+	}()
+
+	return out, nil
+}
+
+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
+}

protocol/ping/ping_test.go

+package ping
+
+import (
+	"testing"
+	"time"
+
+	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
+	peer "github.com/ipfs/go-ipfs/p2p/peer"
+	netutil "github.com/ipfs/go-ipfs/p2p/test/util"
+)
+
+func TestPing(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	h1 := netutil.GenHostSwarm(t, ctx)
+	h2 := netutil.GenHostSwarm(t, ctx)
+
+	err := h1.Connect(ctx, peer.PeerInfo{
+		ID:    h2.ID(),
+		Addrs: h2.Addrs(),
+	})
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ps1 := NewPingService(h1)
+	ps2 := NewPingService(h2)
+
+	testPing(t, ps1, h2.ID())
+	testPing(t, ps2, h1.ID())
+}
+
+func testPing(t *testing.T, ps *PingService, p peer.ID) {
+	pctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	ts, err := ps.Ping(pctx, p)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for i := 0; i < 5; i++ {
+		select {
+		case took := <-ts:
+			t.Log("ping took: ", took)
+		case <-time.After(time.Second * 4):
+			t.Fatal("failed to receive ping")
+		}
+	}
+
+}