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

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

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
-	aliceChannelLink *channelLink
+	aliceServer       *mockServer
+	aliceChannelLink  *channelLink
+	aliceOnionDecoder *mockIteratorDecoder
 
 	bobServer            *mockServer
 	firstBobChannelLink  *channelLink
 	secondBobChannelLink *channelLink
+	bobOnionDecoder      *mockIteratorDecoder
 
-	carolServer      *mockServer
-	carolChannelLink *channelLink
+	carolServer       *mockServer
+	carolChannelLink  *channelLink
+	carolOnionDecoder *mockIteratorDecoder
 
 	hopNetwork
 }
@@ -948,15 +951,18 @@ func newThreeHopNetwork(t testing.TB, aliceChannel, firstBobChannel,
 	}
 
 	return &threeHopNetwork{
-		aliceServer:      aliceServer,
-		aliceChannelLink: aliceChannelLink.(*channelLink),
+		aliceServer:       aliceServer,
+		aliceChannelLink:  aliceChannelLink.(*channelLink),
+		aliceOnionDecoder: aliceDecoder,
 
 		bobServer:            bobServer,
 		firstBobChannelLink:  firstBobChannelLink.(*channelLink),
 		secondBobChannelLink: secondBobChannelLink.(*channelLink),
+		bobOnionDecoder:      bobDecoder,
 
-		carolServer:      carolServer,
-		carolChannelLink: carolChannelLink.(*channelLink),
+		carolServer:       carolServer,
+		carolChannelLink:  carolChannelLink.(*channelLink),
+		carolOnionDecoder: carolDecoder,
 
 		hopNetwork: *hopNetwork,
 	}