add support for connection migration (#4960)

path_manager_outgoing_test.go

@@ -0,0 +1,99 @@
+package quic
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/quic-go/quic-go/internal/protocol"
+	"github.com/quic-go/quic-go/internal/wire"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPathManagerOutgoing(t *testing.T) {
+	connIDs := []protocol.ConnectionID{
+		protocol.ParseConnectionID([]byte{1, 2, 3, 4, 5, 6, 7, 8}),
+		protocol.ParseConnectionID([]byte{2, 3, 4, 5, 6, 7, 8, 9}),
+	}
+	var retiredConnIDs []protocol.ConnectionID
+	pm := newPathManagerOutgoing(
+		func(id pathID) (protocol.ConnectionID, bool) { return connIDs[id], true },
+		func(id pathID) { retiredConnIDs = append(retiredConnIDs, connIDs[id]) },
+		func() {},
+	)
+
+	_, _, _, ok := pm.NextPathToProbe()
+	require.False(t, ok)
+
+	tr1 := &Transport{}
+	var enabled bool
+	p := pm.NewPath(tr1, func() { enabled = true })
+	require.ErrorIs(t, p.Switch(), ErrPathNotValidated)
+
+	errChan := make(chan error, 1)
+	go func() { errChan <- p.Probe(context.Background()) }()
+
+	// wait for the path to be queued for probing
+	time.Sleep(scaleDuration(5 * time.Millisecond))
+
+	require.False(t, enabled)
+	connID, f, tr, ok := pm.NextPathToProbe()
+	require.True(t, ok)
+	require.Equal(t, tr1, tr)
+	require.Equal(t, connIDs[0], connID)
+	require.IsType(t, &wire.PathChallengeFrame{}, f.Frame)
+	pc := f.Frame.(*wire.PathChallengeFrame)
+	require.True(t, enabled)
+
+	_, _, _, ok = pm.NextPathToProbe()
+	require.False(t, ok)
+
+	select {
+	case <-errChan:
+		t.Fatal("should still be probing")
+	default:
+	}
+
+	// acking the frame doesn't complete path validation...
+	f.Handler.OnAcked(f.Frame)
+	select {
+	case <-errChan:
+		t.Fatal("should still be probing")
+	default:
+	}
+
+	require.ErrorIs(t, p.Switch(), ErrPathNotValidated)
+	_, ok = pm.ShouldSwitchPath()
+	require.False(t, ok)
+
+	// ... neither does receiving a random PATH_RESPONSE...
+	pm.HandlePathResponseFrame(&wire.PathResponseFrame{Data: [8]byte{'f', 'o', 'o', 'f', 'o', 'o'}})
+	f.Handler.OnAcked(f.Frame) // doesn't do anything
+	f.Handler.OnLost(f.Frame)  // doesn't do anything
+	select {
+	case <-errChan:
+		t.Fatal("should still be probing")
+	default:
+	}
+
+	// ... only receiving the corresponding PATH_RESPONSE does
+	pm.HandlePathResponseFrame(&wire.PathResponseFrame{Data: pc.Data})
+	select {
+	case err := <-errChan:
+		require.NoError(t, err)
+	case <-time.After(time.Second):
+		t.Fatal("timeout")
+	}
+
+	// receiving it multiple times is ok
+	pm.HandlePathResponseFrame(&wire.PathResponseFrame{Data: pc.Data})
+
+	// now switch to the other path
+	_, ok = pm.ShouldSwitchPath()
+	require.False(t, ok)
+	require.NoError(t, p.Switch())
+	switchToTransport, ok := pm.ShouldSwitchPath()
+	require.True(t, ok)
+	require.Equal(t, tr1, switchToTransport)
+}