Merge pull request #7976 from w3irdrobot/serialize-deserialize-amp

Serialize/deserialize AMP struct in hop

channeldb/payments.go

@@ -1157,6 +1157,10 @@ func serializeHop(w io.Writer, h *route.Hop) error {
 		))
 	}
 
+	if h.AMP != nil {
+		records = append(records, h.AMP.Record())
+	}
+
 	if h.Metadata != nil {
 		records = append(records, record.NewMetadataRecord(&h.Metadata))
 	}
@@ -1301,7 +1305,23 @@ func deserializeHop(r io.Reader) (*route.Hop, error) {
 		}
 	}
 
-	// If the metatdata type is present, remove it from the tlv map and
+	ampType := uint64(record.AMPOnionType)
+	if ampBytes, ok := tlvMap[ampType]; ok {
+		delete(tlvMap, ampType)
+
+		var (
+			amp    = &record.AMP{}
+			ampRec = amp.Record()
+			r      = bytes.NewReader(ampBytes)
+		)
+		err := ampRec.Decode(r, uint64(len(ampBytes)))
+		if err != nil {
+			return nil, err
+		}
+		h.AMP = amp
+	}
+
+	// If the metadata type is present, remove it from the tlv map and
 	// populate directly on the hop.
 	metadataType := uint64(record.MetadataOnionType)
 	if metadata, ok := tlvMap[metadataType]; ok {

channeldb/payments_test.go

@@ -44,11 +44,25 @@ var (
 		LegacyPayload:    true,
 	}
 
+	testHop3 = &route.Hop{
+		PubKeyBytes:      route.NewVertex(pub),
+		ChannelID:        12345,
+		OutgoingTimeLock: 111,
+		AmtToForward:     555,
+		CustomRecords: record.CustomSet{
+			65536: []byte{},
+			80001: []byte{},
+		},
+		AMP:      record.NewAMP([32]byte{0x69}, [32]byte{0x42}, 1),
+		Metadata: []byte{1, 2, 3},
+	}
+
 	testRoute = route.Route{
 		TotalTimeLock: 123,
 		TotalAmount:   1234567,
 		SourcePubKey:  vertex,
 		Hops: []*route.Hop{
+			testHop3,
 			testHop2,
 			testHop1,
 		},

docs/release-notes/release-notes-0.18.0.md

@@ -73,6 +73,8 @@
   a `shutdown` message if there were currently HTLCs on the channel. After this
   change, the shutdown procedure should be compliant with BOLT2 requirements.
 
+* The AMP struct in payment hops will [now be populated](https://github.com/lightningnetwork/lnd/pull/7976) when the AMP TLV is set.
+
 # New Features
 ## Functional Enhancements
 
@@ -281,14 +283,17 @@
 
 * Amin Bashiri
 * Andras Banki-Horvath
+* BitcoinerCoderBob
 * Carla Kirk-Cohen
 * Elle Mouton
 * ErikEk
 * Keagan McClelland
 * Marcos Fernandez Perez
 * Matt Morehouse
 * Slyghtning
+* Tee8z
 * Turtle
 * Ononiwu Maureen Chiamaka
+* w3irdrobot
 * Yong Yu
 * Ziggie

itest/lnd_amp_test.go

@@ -410,6 +410,16 @@ func testSendPaymentAMP(ht *lntest.HarnessTest) {
 		if htlc.Status == lnrpc.HTLCAttempt_SUCCEEDED {
 			succeeded++
 		}
+
+		// When an AMP record is expected, it will only be seen on the
+		// last hop of a route. So we make sure it isn't set on any of
+		// the hops except the last one
+		for _, hop := range htlc.Route.Hops[:len(htlc.Route.Hops)-1] {
+			require.Nil(ht, hop.AmpRecord)
+		}
+
+		lastHop := htlc.Route.Hops[len(htlc.Route.Hops)-1]
+		require.NotNil(ht, lastHop.AmpRecord)
 	}
 
 	const minExpectedShards = 3

lnrpc/routerrpc/router_backend.go

@@ -613,6 +613,18 @@ func (r *RouterBackend) MarshallRoute(route *route.Route) (*lnrpc.Route, error)
 			}
 		}
 
+		var amp *lnrpc.AMPRecord
+		if hop.AMP != nil {
+			rootShare := hop.AMP.RootShare()
+			setID := hop.AMP.SetID()
+
+			amp = &lnrpc.AMPRecord{
+				RootShare:  rootShare[:],
+				SetId:      setID[:],
+				ChildIndex: hop.AMP.ChildIndex(),
+			}
+		}
+
 		resp.Hops[i] = &lnrpc.Hop{
 			ChanId:           hop.ChannelID,
 			ChanCapacity:     int64(chanCapacity),
@@ -627,6 +639,7 @@ func (r *RouterBackend) MarshallRoute(route *route.Route) (*lnrpc.Route, error)
 			CustomRecords: hop.CustomRecords,
 			TlvPayload:    !hop.LegacyPayload,
 			MppRecord:     mpp,
+			AmpRecord:     amp,
 			Metadata:      hop.Metadata,
 			EncryptedData: hop.EncryptedData,
 			TotalAmtMsat:  uint64(hop.TotalAmtMsat),