Merge pull request #3027 from Roasbeef/new-onion-structs

router+build: update to the latest version of lightning-onion

go.mod

@@ -5,7 +5,6 @@ require (
 	github.com/NebulousLabs/fastrand v0.0.0-20180208210444-3cf7173006a0 // indirect
 	github.com/NebulousLabs/go-upnp v0.0.0-20180202185039-29b680b06c82
 	github.com/Yawning/aez v0.0.0-20180114000226-4dad034d9db2
-	github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da // indirect
 	github.com/btcsuite/btcd v0.0.0-20190426011420-63f50db2f70a
 	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f
 	github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d
@@ -29,7 +28,7 @@ require (
 	github.com/juju/version v0.0.0-20180108022336-b64dbd566305 // indirect
 	github.com/kkdai/bstream v0.0.0-20181106074824-b3251f7901ec
 	github.com/lightninglabs/neutrino v0.0.0-20190426010803-a655679fe131
-	github.com/lightningnetwork/lightning-onion v0.0.0-20180605012408-ac4d9da8f1d6
+	github.com/lightningnetwork/lightning-onion v0.0.0-20190430041606-751fb4dd8b72
 	github.com/lightningnetwork/lnd/queue v1.0.1
 	github.com/lightningnetwork/lnd/ticker v1.0.0
 	github.com/ltcsuite/ltcd v0.0.0-20190101042124-f37f8bf35796

go.sum

@@ -14,6 +14,7 @@ github.com/aead/siphash v1.0.1/go.mod h1:Nywa3cDsYNNK3gaciGTWPwHt0wlpNV15vwmswBA
 github.com/boltdb/bolt v1.3.1 h1:JQmyP4ZBrce+ZQu0dY660FMfatumYDLun9hBCUVIkF4=
 github.com/boltdb/bolt v1.3.1/go.mod h1:clJnj/oiGkjum5o1McbSZDSLxVThjynRyGBgiAx27Ps=
 github.com/btcsuite/btcd v0.0.0-20180823030728-d81d8877b8f3/go.mod h1:Dmm/EzmjnCiweXmzRIAiUWCInVmPgjkzgv5k4tVyXiQ=
+github.com/btcsuite/btcd v0.0.0-20181130015935-7d2daa5bfef2/go.mod h1:Jr9bmNVGZ7TH2Ux1QuP0ec+yGgh0gE9FIlkzQiI5bR0=
 github.com/btcsuite/btcd v0.0.0-20190213025234-306aecffea32 h1:qkOC5Gd33k54tobS36cXdAzJbeHaduLtnLQQwNoIi78=
 github.com/btcsuite/btcd v0.0.0-20190213025234-306aecffea32/go.mod h1:DrZx5ec/dmnfpw9KyYoQyYo7d0KEvTkk/5M/vbZjAr8=
 github.com/btcsuite/btcd v0.0.0-20190426011420-63f50db2f70a h1:wH5Nq2kt+BdVJhVyYZD54lHQpz95mog0Z7r1h638TY4=
@@ -110,8 +111,8 @@ github.com/lightninglabs/neutrino v0.0.0-20190313035638-e1ad4c33fb18 h1:lxD7RgKY
 github.com/lightninglabs/neutrino v0.0.0-20190313035638-e1ad4c33fb18/go.mod h1:v6tz6jbuAubTrRpX8ke2KH9sJxml8KlPQTKgo9mAp1Q=
 github.com/lightninglabs/neutrino v0.0.0-20190426010803-a655679fe131 h1:1qKraSAbJFxd2BUHrxFEswNRav749pt4P37Ez8avbAA=
 github.com/lightninglabs/neutrino v0.0.0-20190426010803-a655679fe131/go.mod h1:/XWY/6/btfsknUpLPV8vvIZyhod61zYaUJiE8HxsFUs=
-github.com/lightningnetwork/lightning-onion v0.0.0-20180605012408-ac4d9da8f1d6 h1:ONLGrYJVQdbtP6CE/ff1KNWZtygRGEh12RzonTiCzPs=
+github.com/lightningnetwork/lightning-onion v0.0.0-20190430041606-751fb4dd8b72 h1:KgmypyQfJnEf2vhwboKCtTp4mHxIcLeXPBPWDbPuzFQ=
-github.com/lightningnetwork/lightning-onion v0.0.0-20180605012408-ac4d9da8f1d6/go.mod h1:8EgEt4a/NUOVQd+3kk6n9aZCJ1Ssj96Pb6lCrci+6oc=
+github.com/lightningnetwork/lightning-onion v0.0.0-20190430041606-751fb4dd8b72/go.mod h1:Sooe/CoCqa85JxqHV+IBR2HW+6t2Cv+36awSmoccswM=
 github.com/ltcsuite/ltcd v0.0.0-20190101042124-f37f8bf35796 h1:sjOGyegMIhvgfq5oaue6Td+hxZuf3tDC8lAPrFldqFw=
 github.com/ltcsuite/ltcd v0.0.0-20190101042124-f37f8bf35796/go.mod h1:3p7ZTf9V1sNPI5H8P3NkTFF4LuwMdPl2DodF60qAKqY=
 github.com/ltcsuite/ltcutil v0.0.0-20181217130922-17f3b04680b6/go.mod h1:8Vg/LTOO0KYa/vlHWJ6XZAevPQThGH5sufO0Hrou/lA=
@@ -134,6 +135,7 @@ go.etcd.io/bbolt v1.3.0/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=
 go.etcd.io/bbolt v1.3.2 h1:Z/90sZLPOeCy2PwprqkFa25PdkusRzaj9P8zm/KNyvk=
 go.etcd.io/bbolt v1.3.2/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=
 golang.org/x/crypto v0.0.0-20170930174604-9419663f5a44/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190103213133-ff983b9c42bc/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190211182817-74369b46fc67 h1:ng3VDlRp5/DHpSWl02R4rM9I+8M2rhmsuLwAMmkLQWE=
 golang.org/x/crypto v0.0.0-20190211182817-74369b46fc67/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -156,6 +158,7 @@ golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sys v0.0.0-20180821140842-3b58ed4ad339/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180909124046-d0be0721c37e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190102155601-82a175fd1598/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190209173611-3b5209105503 h1:5SvYFrOM3W8Mexn9/oA44Ji7vhXAZQ9hiP+1Q/DMrWg=
 golang.org/x/sys v0.0.0-20190209173611-3b5209105503/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=

htlcswitch/failure.go

@@ -87,6 +87,13 @@ type ErrorEncrypter interface {
 	// slightly, in that it computes a proper MAC over the error.
 	EncryptFirstHop(lnwire.FailureMessage) (lnwire.OpaqueReason, error)
 
+	// EncryptMalformedError is similar to EncryptFirstHop (it adds the
+	// MAC), but it accepts an opaque failure reason rather than a failure
+	// message. This method is used when we receive an
+	// UpdateFailMalformedHTLC from the remote peer and then need to
+	// convert that into a proper error from only the raw bytes.
+	EncryptMalformedError(lnwire.OpaqueReason) lnwire.OpaqueReason
+
 	// IntermediateEncrypt wraps an already encrypted opaque reason error
 	// in an additional layer of onion encryption. This process repeats
 	// until the error arrives at the source of the payment.
@@ -153,6 +160,17 @@ func (s *SphinxErrorEncrypter) EncryptFirstHop(failure lnwire.FailureMessage) (l
 	return s.EncryptError(true, b.Bytes()), nil
 }
 
+// EncryptMalformedError is similar to EncryptFirstHop (it adds the MAC), but
+// it accepts an opaque failure reason rather than a failure message. This
+// method is used when we receive an UpdateFailMalformedHTLC from the remote
+// peer and then need to convert that into an proper error from only the raw
+// bytes.
+//
+// NOTE: Part of the ErrorEncrypter interface.
+func (s *SphinxErrorEncrypter) EncryptMalformedError(reason lnwire.OpaqueReason) lnwire.OpaqueReason {
+	return s.EncryptError(true, reason)
+}
+
 // IntermediateEncrypt wraps an already encrypted opaque reason error in an
 // additional layer of onion encryption. This process repeats until the error
 // arrives at the source of the payment. We re-encrypt the message on the

htlcswitch/link.go

@@ -2404,10 +2404,24 @@ func (l *channelLink) processRemoteSettleFails(fwdPkg *channeldb.FwdPkg,
 				outgoingHTLCID: pd.ParentIndex,
 				destRef:        pd.DestRef,
 				htlc: &lnwire.UpdateFailHTLC{
-					Reason: lnwire.OpaqueReason(pd.FailReason),
+					Reason: lnwire.OpaqueReason(
+						pd.FailReason,
+					),
 				},
 			}
 
+			// If the failure message lacks an HMAC (but includes
+			// the 4 bytes for encoding the message and padding
+			// lengths, then this means that we received it as an
+			// UpdateFailMalformedHTLC. As a result, we'll signal
+			// that we need to convert this error within the switch
+			// to an actual error, by encrypting it as if we were
+			// the originating hop.
+			convertedErrorSize := lnwire.FailureMessageLength + 4
+			if len(pd.FailReason) == convertedErrorSize {
+				failPacket.convertedError = true
+			}
+
 			// Add the packet to the batch to be forwarded, and
 			// notify the overflow queue that a spare spot has been
 			// freed up within the commitment state.

htlcswitch/mock.go

@@ -368,7 +368,10 @@ func (o *mockObfuscator) EncryptFirstHop(failure lnwire.FailureMessage) (
 
 func (o *mockObfuscator) IntermediateEncrypt(reason lnwire.OpaqueReason) lnwire.OpaqueReason {
 	return reason
+}
 
+func (o *mockObfuscator) EncryptMalformedError(reason lnwire.OpaqueReason) lnwire.OpaqueReason {
+	return reason
 }
 
 // mockDeobfuscator mock implementation of the failure deobfuscator which
@@ -400,6 +403,8 @@ type mockIteratorDecoder struct {
 	mu sync.RWMutex
 
 	responses map[[32]byte][]DecodeHopIteratorResponse
+
+	decodeFail bool
 }
 
 func newMockIteratorDecoder() *mockIteratorDecoder {
@@ -451,6 +456,10 @@ func (p *mockIteratorDecoder) DecodeHopIterators(id []byte,
 			req.OnionReader, req.RHash, req.IncomingCltv,
 		)
 
+		if p.decodeFail {
+			failcode = lnwire.CodeTemporaryChannelFailure
+		}
+
 		resp := DecodeHopIteratorResponse{
 			HopIterator: iterator,
 			FailCode:    failcode,

htlcswitch/packet.go

@@ -61,6 +61,14 @@ type htlcPacket struct {
 	// encrypted with any shared secret.
 	localFailure bool
 
+	// convertedError is set to true if this is an HTLC fail that was
+	// created using an UpdateFailMalformedHTLC from the remote party. If
+	// this is true, then when forwarding this failure packet, we'll need
+	// to wrap it as if we were the first hop if it's a multi-hop HTLC. If
+	// it's a direct HTLC, then we'll decode the error as no encryption has
+	// taken place.
+	convertedError bool
+
 	// hasSource is set to true if the incomingChanID and incomingHTLCID
 	// fields of a forwarded fail packet are already set and do not need to
 	// be looked up in the circuit map.

htlcswitch/switch.go

@@ -956,7 +956,7 @@ func (s *Switch) parseFailedPayment(payment *pendingPayment, pkt *htlcPacket,
 	// The payment never cleared the link, so we don't need to
 	// decrypt the error, simply decode it them report back to the
 	// user.
-	case pkt.localFailure:
+	case pkt.localFailure || pkt.convertedError:
 		var userErr string
 		r := bytes.NewReader(htlc.Reason)
 		failureMsg, err := lnwire.DecodeFailure(r, 0)
@@ -1172,13 +1172,12 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
 		fail, isFail := htlc.(*lnwire.UpdateFailHTLC)
 		if isFail && !packet.hasSource {
 			switch {
+			// No message to encrypt, locally sourced payment.
 			case circuit.ErrorEncrypter == nil:
-				// No message to encrypt, locally sourced
-				// payment.
 
+			// If this is a resolution message, then we'll need to
+			// encrypt it as it's actually internally sourced.
 			case packet.isResolution:
-				// If this is a resolution message, then we'll need to encrypt
-				// it as it's actually internally sourced.
 				var err error
 				// TODO(roasbeef): don't need to pass actually?
 				failure := &lnwire.FailPermanentChannelFailure{}
@@ -1191,6 +1190,25 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
 					log.Error(err)
 				}
 
+			// Alternatively, if the remote party send us an
+			// UpdateFailMalformedHTLC, then we'll need to convert
+			// this into a proper well formatted onion error as
+			// there's no HMAC currently.
+			case packet.convertedError:
+				log.Infof("Converting malformed HTLC error "+
+					"for circuit for Circuit(%x: "+
+					"(%s, %d) <-> (%s, %d))", packet.circuit.PaymentHash,
+					packet.incomingChanID, packet.incomingHTLCID,
+					packet.outgoingChanID, packet.outgoingHTLCID)
+
+				fail.Reason = circuit.ErrorEncrypter.EncryptMalformedError(
+					fail.Reason,
+				)
+				if err != nil {
+					err = fmt.Errorf("unable to obfuscate "+
+						"error: %v", err)
+					log.Error(err)
+				}
 			default:
 				// Otherwise, it's a forwarded error, so we'll perform a
 				// wrapper encryption as normal.

htlcswitch/switch_test.go

@@ -2049,3 +2049,76 @@ func TestMultiHopPaymentForwardingEvents(t *testing.T) {
 		}
 	}
 }
+
+// TestUpdateFailMalformedHTLCErrorConversion tests that we're able to properly
+// convert malformed HTLC errors that originate at the direct link, as well as
+// during multi-hop HTLC forwarding.
+func TestUpdateFailMalformedHTLCErrorConversion(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll create our traditional three hop network.
+	channels, cleanUp, _, err := createClusterChannels(
+		btcutil.SatoshiPerBitcoin*3, btcutil.SatoshiPerBitcoin*5,
+	)
+	if err != nil {
+		t.Fatalf("unable to create channel: %v", err)
+	}
+	defer cleanUp()
+
+	n := newThreeHopNetwork(
+		t, channels.aliceToBob, channels.bobToAlice,
+		channels.bobToCarol, channels.carolToBob, testStartingHeight,
+	)
+	if err := n.start(); err != nil {
+		t.Fatalf("unable to start three hop network: %v", err)
+	}
+
+	assertPaymentFailure := func(t *testing.T) {
+		// With the decoder modified, we'll now attempt to send a
+		// payment from Alice to carol.
+		finalAmt := lnwire.NewMSatFromSatoshis(100000)
+		htlcAmt, totalTimelock, hops := generateHops(
+			finalAmt, testStartingHeight, n.firstBobChannelLink,
+			n.carolChannelLink,
+		)
+		firstHop := n.firstBobChannelLink.ShortChanID()
+		_, err = makePayment(
+			n.aliceServer, n.carolServer, firstHop, hops, finalAmt,
+			htlcAmt, totalTimelock,
+		).Wait(30 * time.Second)
+
+		// The payment should fail as Carol is unable to decode the
+		// onion blob sent to her.
+		if err == nil {
+			t.Fatalf("unable to send payment: %v", err)
+		}
+
+		fwdingErr := err.(*ForwardingError)
+		failureMsg := fwdingErr.FailureMessage
+		if _, ok := failureMsg.(*lnwire.FailTemporaryChannelFailure); !ok {
+			t.Fatalf("expected temp chan failure instead got: %v",
+				fwdingErr.FailureMessage)
+		}
+	}
+
+	t.Run("multi-hop error conversion", func(t *testing.T) {
+		// Now that we have our network up, we'll modify the hop
+		// iterator for the Bob <-> Carol channel to fail to decode in
+		// order to simulate either a replay attack or an issue
+		// decoding the onion.
+		n.carolOnionDecoder.decodeFail = true
+
+		assertPaymentFailure(t)
+	})
+
+	t.Run("direct channel error conversion", func(t *testing.T) {
+		// Similar to the above test case, we'll now make the Alice <->
+		// Bob link always fail to decode an onion. This differs from
+		// the above test case in that there's no encryption on the
+		// error at all since Alice will directly receive a
+		// UpdateFailMalformedHTLC message.
+		n.bobOnionDecoder.decodeFail = true
+
+		assertPaymentFailure(t)
+	})
+}

htlcswitch/test_utils.go

@@ -589,15 +589,18 @@ func generateRoute(hops ...ForwardingInfo) ([lnwire.OnionPacketSize]byte, error)
 
 // threeHopNetwork is used for managing the created cluster of 3 hops.
 type threeHopNetwork struct {
-	aliceServer      *mockServer
+	aliceServer       *mockServer
-	aliceChannelLink *channelLink
+	aliceChannelLink  *channelLink
+	aliceOnionDecoder *mockIteratorDecoder
 
 	bobServer            *mockServer
 	firstBobChannelLink  *channelLink
 	secondBobChannelLink *channelLink
+	bobOnionDecoder      *mockIteratorDecoder
 
-	carolServer      *mockServer
+	carolServer       *mockServer
-	carolChannelLink *channelLink
+	carolChannelLink  *channelLink
+	carolOnionDecoder *mockIteratorDecoder
 
 	hopNetwork
 }
@@ -948,15 +951,18 @@ func newThreeHopNetwork(t testing.TB, aliceChannel, firstBobChannel,
 	}
 
 	return &threeHopNetwork{
-		aliceServer:      aliceServer,
+		aliceServer:       aliceServer,
-		aliceChannelLink: aliceChannelLink.(*channelLink),
+		aliceChannelLink:  aliceChannelLink.(*channelLink),
+		aliceOnionDecoder: aliceDecoder,
 
 		bobServer:            bobServer,
 		firstBobChannelLink:  firstBobChannelLink.(*channelLink),
 		secondBobChannelLink: secondBobChannelLink.(*channelLink),
+		bobOnionDecoder:      bobDecoder,
 
-		carolServer:      carolServer,
+		carolServer:       carolServer,
-		carolChannelLink: carolChannelLink.(*channelLink),
+		carolChannelLink:  carolChannelLink.(*channelLink),
+		carolOnionDecoder: carolDecoder,
 
 		hopNetwork: *hopNetwork,
 	}

lnd_test.go

@@ -3522,13 +3522,10 @@ func testSphinxReplayPersistence(net *lntest.NetworkHarness, t *harnessTest) {
 
 	// Construct the response we expect after sending a duplicate packet
 	// that fails due to sphinx replay detection.
-	replayErr := fmt.Sprintf("unable to route payment to destination: "+
+	replayErr := "TemporaryChannelFailure"
-		"TemporaryChannelFailure: unable to de-obfuscate onion failure, "+
+	if !strings.Contains(resp.PaymentError, replayErr) {
-		"htlc with hash(%x): unable to retrieve onion failure",
+		t.Fatalf("received payment error: %v, expected %v",
-		invoiceResp.RHash)
+			resp.PaymentError, replayErr)
-
-	if resp.PaymentError != replayErr {
-		t.Fatalf("received payment error: %v", resp.PaymentError)
 	}
 
 	// Since the payment failed, the balance should still be left

lnwire/onion_error.go

@@ -26,9 +26,9 @@ type FailureMessage interface {
 	Error() string
 }
 
-// failureMessageLength is the size of the failure message plus the size of
+// FailureMessageLength is the size of the failure message plus the size of
 // padding. The FailureMessage message should always be EXACTLY this size.
-const failureMessageLength = 256
+const FailureMessageLength = 256
 
 const (
 	// FlagBadOnion error flag describes an unparsable, encrypted by
@@ -1101,7 +1101,7 @@ func DecodeFailure(r io.Reader, pver uint32) (FailureMessage, error) {
 	if err := ReadElement(r, &failureLength); err != nil {
 		return nil, fmt.Errorf("unable to read error len: %v", err)
 	}
-	if failureLength > failureMessageLength {
+	if failureLength > FailureMessageLength {
 		return nil, fmt.Errorf("failure message is too "+
 			"long: %v", failureLength)
 	}
@@ -1170,14 +1170,14 @@ func EncodeFailure(w io.Writer, failure FailureMessage, pver uint32) error {
 	// The combined size of this message must be below the max allowed
 	// failure message length.
 	failureMessage := failureMessageBuffer.Bytes()
-	if len(failureMessage) > failureMessageLength {
+	if len(failureMessage) > FailureMessageLength {
 		return fmt.Errorf("failure message exceed max "+
 			"available size: %v", len(failureMessage))
 	}
 
 	// Finally, we'll add some padding in order to ensure that all failure
 	// messages are fixed size.
-	pad := make([]byte, failureMessageLength-len(failureMessage))
+	pad := make([]byte, FailureMessageLength-len(failureMessage))
 
 	return WriteElements(w,
 		uint16(len(failureMessage)),

routing/pathfind_test.go

@@ -807,19 +807,22 @@ func testBasicGraphPathFindingCase(t *testing.T, graphInstance *testGraphInstanc
 	// Next, we'll assert that the "next hop" field in each route payload
 	// properly points to the channel ID that the HTLC should be forwarded
 	// along.
-	hopPayloads := route.ToHopPayloads()
+	sphinxPath, err := route.ToSphinxPath()
-	if len(hopPayloads) != expectedHopCount {
+	if err != nil {
+		t.Fatalf("unable to make sphinx path: %v", err)
+	}
+	if sphinxPath.TrueRouteLength() != expectedHopCount {
 		t.Fatalf("incorrect number of hop payloads: expected %v, got %v",
-			expectedHopCount, len(hopPayloads))
+			expectedHopCount, sphinxPath.TrueRouteLength())
 	}
 
 	// Hops should point to the next hop
 	for i := 0; i < len(expectedHops)-1; i++ {
 		var expectedHop [8]byte
 		binary.BigEndian.PutUint64(expectedHop[:], route.Hops[i+1].ChannelID)
-		if !bytes.Equal(hopPayloads[i].NextAddress[:], expectedHop[:]) {
+		if !bytes.Equal(sphinxPath[i].HopData.NextAddress[:], expectedHop[:]) {
 			t.Fatalf("first hop has incorrect next hop: expected %x, got %x",
-				expectedHop[:], hopPayloads[i].NextAddress)
+				expectedHop[:], sphinxPath[i].HopData.NextAddress)
 		}
 	}
 
@@ -827,9 +830,9 @@ func testBasicGraphPathFindingCase(t *testing.T, graphInstance *testGraphInstanc
 	// to indicate it's the exit hop.
 	var exitHop [8]byte
 	lastHopIndex := len(expectedHops) - 1
-	if !bytes.Equal(hopPayloads[lastHopIndex].NextAddress[:], exitHop[:]) {
+	if !bytes.Equal(sphinxPath[lastHopIndex].HopData.NextAddress[:], exitHop[:]) {
 		t.Fatalf("first hop has incorrect next hop: expected %x, got %x",
-			exitHop[:], hopPayloads[lastHopIndex].NextAddress)
+			exitHop[:], sphinxPath[lastHopIndex].HopData.NextAddress)
 	}
 
 	var expectedTotalFee lnwire.MilliSatoshi

routing/route/route.go

@@ -104,40 +104,6 @@ func (r *Route) HopFee(hopIndex int) lnwire.MilliSatoshi {
 	return incomingAmt - r.Hops[hopIndex].AmtToForward
 }
 
-// ToHopPayloads converts a complete route into the series of per-hop payloads
-// that is to be encoded within each HTLC using an opaque Sphinx packet.
-func (r *Route) ToHopPayloads() []sphinx.HopData {
-	hopPayloads := make([]sphinx.HopData, len(r.Hops))
-
-	// For each hop encoded within the route, we'll convert the hop struct
-	// to the matching per-hop payload struct as used by the sphinx
-	// package.
-	for i, hop := range r.Hops {
-		hopPayloads[i] = sphinx.HopData{
-			// TODO(roasbeef): properly set realm, make sphinx type
-			// an enum actually?
-			Realm:         0,
-			ForwardAmount: uint64(hop.AmtToForward),
-			OutgoingCltv:  hop.OutgoingTimeLock,
-		}
-
-		// As a base case, the next hop is set to all zeroes in order
-		// to indicate that the "last hop" as no further hops after it.
-		nextHop := uint64(0)
-
-		// If we aren't on the last hop, then we set the "next address"
-		// field to be the channel that directly follows it.
-		if i != len(r.Hops)-1 {
-			nextHop = r.Hops[i+1].ChannelID
-		}
-
-		binary.BigEndian.PutUint64(hopPayloads[i].NextAddress[:],
-			nextHop)
-	}
-
-	return hopPayloads
-}
-
 // NewRouteFromHops creates a new Route structure from the minimally required
 // information to perform the payment. It infers fee amounts and populates the
 // node, chan and prev/next hop maps.
@@ -163,3 +129,49 @@ func NewRouteFromHops(amtToSend lnwire.MilliSatoshi, timeLock uint32,
 
 	return route, nil
 }
+
+// ToSphinxPath converts a complete route into a sphinx PaymentPath that
+// contains the per-hop paylods used to encoding the HTLC routing data for each
+// hop in the route.
+func (r *Route) ToSphinxPath() (*sphinx.PaymentPath, error) {
+	var path sphinx.PaymentPath
+
+	// For each hop encoded within the route, we'll convert the hop struct
+	// to an OnionHop with matching per-hop payload within the path as used
+	// by the sphinx package.
+	for i, hop := range r.Hops {
+		pub, err := btcec.ParsePubKey(
+			hop.PubKeyBytes[:], btcec.S256(),
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		path[i] = sphinx.OnionHop{
+			NodePub: *pub,
+			HopData: sphinx.HopData{
+				// TODO(roasbeef): properly set realm, make
+				// sphinx type an enum actually?
+				Realm:         [1]byte{0},
+				ForwardAmount: uint64(hop.AmtToForward),
+				OutgoingCltv:  hop.OutgoingTimeLock,
+			},
+		}
+
+		// As a base case, the next hop is set to all zeroes in order
+		// to indicate that the "last hop" as no further hops after it.
+		nextHop := uint64(0)
+
+		// If we aren't on the last hop, then we set the "next address"
+		// field to be the channel that directly follows it.
+		if i != len(r.Hops)-1 {
+			nextHop = r.Hops[i+1].ChannelID
+		}
+
+		binary.BigEndian.PutUint64(
+			path[i].HopData.NextAddress[:], nextHop,
+		)
+	}
+
+	return &path, nil
+}

routing/router.go

@@ -1467,30 +1467,25 @@ func generateSphinxPacket(rt *route.Route, paymentHash []byte) ([]byte,
 		return nil, nil, route.ErrNoRouteHopsProvided
 	}
 
-	// First obtain all the public keys along the route which are contained
+	// Now that we know we have an actual route, we'll map the route into a
-	// in each hop.
+	// sphinx payument path which includes per-hop paylods for each hop
-	nodes := make([]*btcec.PublicKey, len(rt.Hops))
+	// that give each node within the route the necessary information
-	for i, hop := range rt.Hops {
+	// (fees, CLTV value, etc) to properly forward the payment.
-		pub, err := btcec.ParsePubKey(hop.PubKeyBytes[:],
+	sphinxPath, err := rt.ToSphinxPath()
-			btcec.S256())
+	if err != nil {
-		if err != nil {
+		return nil, nil, err
-			return nil, nil, err
-		}
-
-		nodes[i] = pub
 	}
 
-	// Next we generate the per-hop payload which gives each node within
-	// the route the necessary information (fees, CLTV value, etc) to
-	// properly forward the payment.
-	hopPayloads := rt.ToHopPayloads()
-
 	log.Tracef("Constructed per-hop payloads for payment_hash=%x: %v",
 		paymentHash[:], newLogClosure(func() string {
-			return spew.Sdump(hopPayloads)
+			return spew.Sdump(sphinxPath[:sphinxPath.TrueRouteLength()])
 		}),
 	)
 
+	// Generate a new random session key to ensure that we don't trigger
+	// any replay.
+	//
+	// TODO(roasbeef): add more sources of randomness?
 	sessionKey, err := btcec.NewPrivateKey(btcec.S256())
 	if err != nil {
 		return nil, nil, err
@@ -1499,7 +1494,7 @@ func generateSphinxPacket(rt *route.Route, paymentHash []byte) ([]byte,
 	// Next generate the onion routing packet which allows us to perform
 	// privacy preserving source routing across the network.
 	sphinxPacket, err := sphinx.NewOnionPacket(
-		nodes, sessionKey, hopPayloads, paymentHash,
+		sphinxPath, sessionKey, paymentHash,
 	)
 	if err != nil {
 		return nil, nil, err
@@ -1523,7 +1518,7 @@ func generateSphinxPacket(rt *route.Route, paymentHash []byte) ([]byte,
 
 	return onionBlob.Bytes(), &sphinx.Circuit{
 		SessionKey:  sessionKey,
-		PaymentPath: nodes,
+		PaymentPath: sphinxPath.NodeKeys(),
 	}, nil
 }