htlcswitch/hop/payload: parse option_mpp

htlcswitch/hop/payload.go

@@ -81,6 +81,10 @@ type Payload struct {
 	// FwdInfo holds the basic parameters required for HTLC forwarding, e.g.
 	// amount, cltv, and next hop.
 	FwdInfo ForwardingInfo
+
+	// MPP holds the info provided in an option_mpp record when parsed from
+	// a TLV onion payload.
+	MPP *record.MPP
 }
 
 // NewLegacyPayload builds a Payload from the amount, cltv, and next hop
@@ -105,12 +109,14 @@ func NewPayloadFromReader(r io.Reader) (*Payload, error) {
 		cid  uint64
 		amt  uint64
 		cltv uint32
+		mpp  = &record.MPP{}
 	)
 
 	tlvStream, err := tlv.NewStream(
 		record.NewAmtToFwdRecord(&amt),
 		record.NewLockTimeRecord(&cltv),
 		record.NewNextHopIDRecord(&cid),
+		mpp.Record(),
 	)
 	if err != nil {
 		return nil, err
@@ -151,6 +157,12 @@ func NewPayloadFromReader(r io.Reader) (*Payload, error) {
 		return nil, err
 	}
 
+	// If no MPP field was parsed, set the MPP field on the resulting
+	// payload to nil.
+	if _, ok := parsedTypes[record.MPPOnionType]; !ok {
+		mpp = nil
+	}
+
 	return &Payload{
 		FwdInfo: ForwardingInfo{
 			Network:         BitcoinNetwork,
@@ -158,6 +170,7 @@ func NewPayloadFromReader(r io.Reader) (*Payload, error) {
 			AmountToForward: lnwire.MilliSatoshi(amt),
 			OutgoingCTLV:    cltv,
 		},
+		MPP: mpp,
 	}, nil
 }
 
@@ -179,6 +192,7 @@ func ValidateParsedPayloadTypes(parsedTypes tlv.TypeSet,
 	_, hasAmt := parsedTypes[record.AmtOnionType]
 	_, hasLockTime := parsedTypes[record.LockTimeOnionType]
 	_, hasNextHop := parsedTypes[record.NextHopOnionType]
+	_, hasMPP := parsedTypes[record.MPPOnionType]
 
 	switch {
 
@@ -207,6 +221,14 @@ func ValidateParsedPayloadTypes(parsedTypes tlv.TypeSet,
 			Violation: IncludedViolation,
 			FinalHop:  true,
 		}
+
+	// Intermediate nodes should never receive MPP fields.
+	case !isFinalHop && hasMPP:
+		return ErrInvalidPayload{
+			Type:      record.MPPOnionType,
+			Violation: IncludedViolation,
+			FinalHop:  isFinalHop,
+		}
 	}
 
 	return nil

htlcswitch/hop/payload_test.go

@@ -6,13 +6,15 @@ import (
 	"testing"
 
 	"github.com/lightningnetwork/lnd/htlcswitch/hop"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/record"
 )
 
 type decodePayloadTest struct {
-	name    string
+	name          string
-	payload []byte
+	payload       []byte
-	expErr  error
+	expErr        error
+	shouldHaveMPP bool
 }
 
 var decodePayloadTests = []decodePayloadTest{
@@ -79,9 +81,9 @@ var decodePayloadTests = []decodePayloadTest{
 	},
 	{
 		name:    "required type after omitted hop id",
-		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x08, 0x00},
+		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x0a, 0x00},
 		expErr: hop.ErrInvalidPayload{
-			Type:      8,
+			Type:      10,
 			Violation: hop.RequiredViolation,
 			FinalHop:  true,
 		},
@@ -89,10 +91,10 @@ var decodePayloadTests = []decodePayloadTest{
 	{
 		name: "required type after included hop id",
 		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x06, 0x08, 0x01, 0x00,
-			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0a, 0x00,
 		},
 		expErr: hop.ErrInvalidPayload{
-			Type:      8,
+			Type:      10,
 			Violation: hop.RequiredViolation,
 			FinalHop:  false,
 		},
@@ -112,7 +114,7 @@ var decodePayloadTests = []decodePayloadTest{
 			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 		},
 		expErr: hop.ErrInvalidPayload{
-			Type:      6,
+			Type:      record.NextHopOnionType,
 			Violation: hop.IncludedViolation,
 			FinalHop:  true,
 		},
@@ -128,6 +130,60 @@ var decodePayloadTests = []decodePayloadTest{
 			FinalHop:  false,
 		},
 	},
+	{
+		name: "valid intermediate hop",
+		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x06, 0x08, 0x01, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+		expErr: nil,
+	},
+	{
+		name:    "valid final hop",
+		payload: []byte{0x02, 0x00, 0x04, 0x00},
+		expErr:  nil,
+	},
+	{
+		name: "intermediate hop with mpp",
+		payload: []byte{
+			// amount
+			0x02, 0x00,
+			// cltv
+			0x04, 0x00,
+			// next hop id
+			0x06, 0x08,
+			0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			// mpp
+			0x08, 0x21,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x08,
+		},
+		expErr: hop.ErrInvalidPayload{
+			Type:      record.MPPOnionType,
+			Violation: hop.IncludedViolation,
+			FinalHop:  false,
+		},
+	},
+	{
+		name: "final hop with mpp",
+		payload: []byte{
+			// amount
+			0x02, 0x00,
+			// cltv
+			0x04, 0x00,
+			// mpp
+			0x08, 0x21,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x08,
+		},
+		expErr:        nil,
+		shouldHaveMPP: true,
+	},
 }
 
 // TestDecodeHopPayloadRecordValidation asserts that parsing the payloads in the
@@ -142,9 +198,37 @@ func TestDecodeHopPayloadRecordValidation(t *testing.T) {
 }
 
 func testDecodeHopPayloadValidation(t *testing.T, test decodePayloadTest) {
-	_, err := hop.NewPayloadFromReader(bytes.NewReader(test.payload))
+	var (
+		testTotalMsat = lnwire.MilliSatoshi(8)
+		testAddr      = [32]byte{
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+		}
+	)
+
+	p, err := hop.NewPayloadFromReader(bytes.NewReader(test.payload))
 	if !reflect.DeepEqual(test.expErr, err) {
 		t.Fatalf("expected error mismatch, want: %v, got: %v",
 			test.expErr, err)
 	}
+	if err != nil {
+		return
+	}
+
+	// Assert MPP fields if we expect them.
+	if test.shouldHaveMPP {
+		if p.MPP == nil {
+			t.Fatalf("payload should have MPP record")
+		}
+		if p.MPP.TotalMsat() != testTotalMsat {
+			t.Fatalf("invalid total msat")
+		}
+		if p.MPP.PaymentAddr() != testAddr {
+			t.Fatalf("invalid payment addr")
+		}
+	} else if p.MPP != nil {
+		t.Fatalf("unexpected MPP payload")
+	}
 }