channeldb: add Route (de)serialization + test

We will store the routes used during payment attempts, so we need
serialization code.

channeldb/payments.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/coreos/bbolt"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/routing/route"
 )
 
 var (
@@ -328,3 +329,84 @@ func deserializeOutgoingPayment(r io.Reader) (*OutgoingPayment, error) {
 
 	return p, nil
 }
+
+func serializeHop(w io.Writer, h *route.Hop) error {
+	if err := WriteElements(w,
+		h.PubKeyBytes[:], h.ChannelID, h.OutgoingTimeLock,
+		h.AmtToForward,
+	); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func deserializeHop(r io.Reader) (*route.Hop, error) {
+	h := &route.Hop{}
+
+	var pub []byte
+	if err := ReadElements(r, &pub); err != nil {
+		return nil, err
+	}
+	copy(h.PubKeyBytes[:], pub)
+
+	if err := ReadElements(r,
+		&h.ChannelID, &h.OutgoingTimeLock, &h.AmtToForward,
+	); err != nil {
+		return nil, err
+	}
+
+	return h, nil
+}
+
+func serializeRoute(w io.Writer, r route.Route) error {
+	if err := WriteElements(w,
+		r.TotalTimeLock, r.TotalFees, r.TotalAmount, r.SourcePubKey[:],
+	); err != nil {
+		return err
+	}
+
+	if err := WriteElements(w, uint32(len(r.Hops))); err != nil {
+		return err
+	}
+
+	for _, h := range r.Hops {
+		if err := serializeHop(w, h); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func deserializeRoute(r io.Reader) (route.Route, error) {
+	rt := route.Route{}
+	if err := ReadElements(r,
+		&rt.TotalTimeLock, &rt.TotalFees, &rt.TotalAmount,
+	); err != nil {
+		return rt, err
+	}
+
+	var pub []byte
+	if err := ReadElements(r, &pub); err != nil {
+		return rt, err
+	}
+	copy(rt.SourcePubKey[:], pub)
+
+	var numHops uint32
+	if err := ReadElements(r, &numHops); err != nil {
+		return rt, err
+	}
+
+	var hops []*route.Hop
+	for i := uint32(0); i < numHops; i++ {
+		hop, err := deserializeHop(r)
+		if err != nil {
+			return rt, err
+		}
+		hops = append(hops, hop)
+	}
+	rt.Hops = hops
+
+	return rt, nil
+}

channeldb/payments_test.go

@@ -8,8 +8,33 @@ import (
 	"testing"
 	"time"
 
+	"github.com/btcsuite/btcd/btcec"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/routing/route"
+)
+
+var (
+	priv, _ = btcec.NewPrivateKey(btcec.S256())
+	pub     = priv.PubKey()
+
+	testHop = &route.Hop{
+		PubKeyBytes:      route.NewVertex(pub),
+		ChannelID:        12345,
+		OutgoingTimeLock: 111,
+		AmtToForward:     555,
+	}
+
+	testRoute = route.Route{
+		TotalTimeLock: 123,
+		TotalFees:     999,
+		TotalAmount:   1234567,
+		SourcePubKey:  route.NewVertex(pub),
+		Hops: []*route.Hop{
+			testHop,
+			testHop,
+		},
+	}
 )
 
 func makeFakePayment() *OutgoingPayment {
@@ -251,3 +276,24 @@ func TestPaymentStatusWorkflow(t *testing.T) {
 		}
 	}
 }
+
+func TestRouteSerialization(t *testing.T) {
+	t.Parallel()
+
+	var b bytes.Buffer
+	if err := serializeRoute(&b, testRoute); err != nil {
+		t.Fatal(err)
+	}
+
+	r := bytes.NewReader(b.Bytes())
+	route2, err := deserializeRoute(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !reflect.DeepEqual(testRoute, route2) {
+		t.Fatalf("routes not equal: \n%v vs \n%v",
+			spew.Sdump(testRoute), spew.Sdump(route2))
+	}
+
+}