pass chan updates on failure

common/chan_update.go

@@ -0,0 +1,38 @@
+package common
+
+import (
+	"bytes"
+	"time"
+
+	"github.com/breez/lspd/lightning"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/lightningnetwork/lnd/lnwire"
+)
+
+func ConstructChanUpdate(
+	chainhash chainhash.Hash,
+	node []byte,
+	destination []byte,
+	scid lightning.ShortChannelID,
+	timeLockDelta uint16,
+	htlcMinimumMsat,
+	htlcMaximumMsat uint64,
+) lnwire.ChannelUpdate {
+	channelFlags := lnwire.ChanUpdateChanFlags(0)
+	if bytes.Compare(node, destination) > 0 {
+		channelFlags = 1
+	}
+
+	return lnwire.ChannelUpdate{
+		ChainHash:       chainhash,
+		ShortChannelID:  scid.ToLnwire(),
+		Timestamp:       uint32(time.Now().Unix()),
+		TimeLockDelta:   timeLockDelta,
+		HtlcMinimumMsat: lnwire.MilliSatoshi(htlcMinimumMsat),
+		HtlcMaximumMsat: lnwire.MilliSatoshi(htlcMaximumMsat),
+		BaseFee:         0,
+		FeeRate:         0,
+		MessageFlags:    lnwire.ChanUpdateRequiredMaxHtlc,
+		ChannelFlags:    channelFlags,
+	}
+}

common/intercept_handler.go

@@ -1,10 +1,13 @@
 package common
 
 import (
+	"bytes"
 	"fmt"
+	"log"
 
 	"github.com/breez/lspd/lightning"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/lightningnetwork/lnd/lnwire"
 )
 
 type InterceptAction int
@@ -27,6 +30,30 @@ var (
 	FAILURE_INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS InterceptFailureCode = []byte{0x40, 0x0F}
 )
 
+func FailureTemporaryChannelFailure(update *lnwire.ChannelUpdate) []byte {
+	var buf bytes.Buffer
+	msg := lnwire.NewTemporaryChannelFailure(update)
+	err := lnwire.EncodeFailureMessage(&buf, msg, 0)
+	if err != nil {
+		log.Printf("Failed to encode failure message for temporary channel failure: %v", err)
+		return FAILURE_TEMPORARY_CHANNEL_FAILURE
+	}
+
+	return buf.Bytes()
+}
+
+func FailureIncorrectCltvExpiry(cltvExpiry uint32, update lnwire.ChannelUpdate) []byte {
+	var buf bytes.Buffer
+	msg := lnwire.NewIncorrectCltvExpiry(cltvExpiry, update)
+	err := lnwire.EncodeFailureMessage(&buf, msg, 0)
+	if err != nil {
+		log.Printf("Failed to encode failure message for incorrect cltv expiry: %v", err)
+		return FAILURE_INCORRECT_CLTV_EXPIRY
+	}
+
+	return buf.Bytes()
+}
+
 type InterceptRequest struct {
 	// Identifier that uniquely identifies this htlc.
 	// For cln, that's hash of the next onion or the shared secret.

interceptor/intercept_handler.go

@@ -111,7 +111,7 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 			log.Printf("IsConnected(%x) error: %v", nextHop, err)
 			return &common.InterceptResult{
 				Action:         common.INTERCEPT_FAIL_HTLC_WITH_CODE,
-				FailureMessage: common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+				FailureMessage: common.FailureTemporaryChannelFailure(nil),
 			}, nil
 		}
 
@@ -160,6 +160,17 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 			}, nil
 		}
 
+		// In case we fail with an error, this is the used channel update.
+		chanUpdate := common.ConstructChanUpdate(
+			i.node.ChainHash,
+			i.node.NodeId,
+			destination,
+			req.Scid,
+			uint16(i.node.NodeConfig.TimeLockDelta),
+			i.node.NodeConfig.MinHtlcMsat,
+			req.IncomingAmountMsat,
+		)
+
 		// The first htlc of a MPP will open the channel.
 		if channelPoint == nil {
 			// TODO: When opening_fee_params is enforced, turn this check in a temporary channel failure.
@@ -179,7 +190,7 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 				log.Printf("paymentHash: %s, outgoingExpiry: %v, incomingExpiry: %v, i.node.NodeConfig.TimeLockDelta: %v", reqPaymentHashStr, req.OutgoingExpiry, req.IncomingExpiry, i.node.NodeConfig.TimeLockDelta)
 				return common.InterceptResult{
 					Action:         common.INTERCEPT_FAIL_HTLC_WITH_CODE,
-					FailureMessage: common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+					FailureMessage: common.FailureIncorrectCltvExpiry(req.IncomingExpiry, chanUpdate),
 				}, nil
 			}
 
@@ -188,7 +199,7 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 				log.Printf("paymentHash: %s, time.Parse(%s, %s) failed. Failing channel open: %v", reqPaymentHashStr, lsps0.TIME_FORMAT, params.ValidUntil, err)
 				return common.InterceptResult{
 					Action:         common.INTERCEPT_FAIL_HTLC_WITH_CODE,
-					FailureMessage: common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+					FailureMessage: common.FailureTemporaryChannelFailure(&chanUpdate),
 				}, nil
 			}
 
@@ -199,7 +210,7 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 					log.Printf("Intercepted expired payment registration. Failing payment. payment hash: %s, valid until: %s", reqPaymentHashStr, params.ValidUntil)
 					return common.InterceptResult{
 						Action:         common.INTERCEPT_FAIL_HTLC_WITH_CODE,
-						FailureMessage: common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+						FailureMessage: common.FailureTemporaryChannelFailure(&chanUpdate),
 					}, nil
 				}
 
@@ -211,7 +222,7 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 				log.Printf("paymentHash: %s, openChannel(%x, %v) err: %v", reqPaymentHashStr, destination, incomingAmountMsat, err)
 				return common.InterceptResult{
 					Action:         common.INTERCEPT_FAIL_HTLC_WITH_CODE,
-					FailureMessage: common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+					FailureMessage: common.FailureTemporaryChannelFailure(&chanUpdate),
 				}, nil
 			}
 		}
@@ -238,7 +249,7 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 					log.Printf("paymentHash: %s, insertChannel error: %v", reqPaymentHashStr, err)
 					return common.InterceptResult{
 						Action:         common.INTERCEPT_FAIL_HTLC_WITH_CODE,
-						FailureMessage: common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+						FailureMessage: common.FailureTemporaryChannelFailure(&chanUpdate),
 					}, nil
 				}
 
@@ -271,7 +282,7 @@ func (i *Interceptor) Intercept(req common.InterceptRequest) common.InterceptRes
 		log.Printf("paymentHash: %s, Error: Channel failed to open... timed out. ", reqPaymentHashStr)
 		return common.InterceptResult{
 			Action:         common.INTERCEPT_FAIL_HTLC_WITH_CODE,
-			FailureMessage: common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+			FailureMessage: common.FailureTemporaryChannelFailure(&chanUpdate),
 		}, nil
 	})
 

itest/cltv_test.go

@@ -54,5 +54,5 @@ func testInvalidCltv(p *testParams) {
 	// Decrement the delay in the first hop, so the cltv delta will become 143 (too little)
 	route.Hops[0].Delay--
 	_, err := alice.PayViaRoute(outerAmountMsat, outerInvoice.paymentHash, outerInvoice.paymentSecret, route)
-	assert.Contains(p.t, err.Error(), "WIRE_TEMPORARY_CHANNEL_FAILURE")
+	assert.Contains(p.t, err.Error(), "WIRE_INCORRECT_CLTV_EXPIRY")
 }

lsps2/intercept_handler.go

@@ -114,7 +114,7 @@ type paymentChanOpenedEvent struct {
 
 type paymentFailureEvent struct {
 	paymentId string
-	code      common.InterceptFailureCode
+	message   common.InterceptFailureCode
 }
 
 func (i *Interceptor) Start(ctx context.Context) {
@@ -135,7 +135,7 @@ func (i *Interceptor) Start(ctx context.Context) {
 		case paymentId := <-i.paymentReady:
 			i.handlePaymentReady(paymentId)
 		case ev := <-i.paymentFailure:
-			i.handlePaymentFailure(ev.paymentId, ev.code)
+			i.handlePaymentFailure(ev.paymentId, ev.message)
 		case ev := <-i.paymentChanOpened:
 			i.handlePaymentChanOpened(ev)
 		}
@@ -189,7 +189,7 @@ func (i *Interceptor) handleNewPart(part *partState) {
 				// a goroutine.
 				i.paymentFailure <- &paymentFailureEvent{
 					paymentId: paymentId,
-					code:      common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+					message:   common.FailureTemporaryChannelFailure(nil),
 				}
 			case <-payment.timeoutChan:
 				// Stop listening for timeouts when the payment is ready.
@@ -284,7 +284,17 @@ func (i *Interceptor) processPart(payment *paymentState, part *partState) {
 	// Make sure the cltv delta is enough (actual cltv delta + 2).
 	if int64(part.req.IncomingExpiry)-int64(part.req.OutgoingExpiry) <
 		int64(i.config.TimeLockDelta)+2 {
-		i.failPart(payment, part, common.FAILURE_INCORRECT_CLTV_EXPIRY)
+		peerid, _ := hex.DecodeString(payment.registration.PeerId)
+		chanUpdate := common.ConstructChanUpdate(
+			i.config.ChainHash,
+			i.config.NodeId,
+			peerid,
+			payment.fakeScid,
+			uint16(i.config.TimeLockDelta),
+			i.config.HtlcMinimumMsat,
+			payment.paymentSizeMsat,
+		)
+		i.failPart(payment, part, common.FailureIncorrectCltvExpiry(part.req.IncomingExpiry, chanUpdate))
 		return
 	}
 
@@ -376,6 +386,16 @@ func (i *Interceptor) handlePaymentReady(paymentId string) {
 // a goroutine.
 func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 	destination, _ := hex.DecodeString(payment.registration.PeerId)
+	peerid, _ := hex.DecodeString(payment.registration.PeerId)
+	chanUpdate := common.ConstructChanUpdate(
+		i.config.ChainHash,
+		i.config.NodeId,
+		peerid,
+		payment.fakeScid,
+		uint16(i.config.TimeLockDelta),
+		i.config.HtlcMinimumMsat,
+		payment.paymentSizeMsat,
+	)
 
 	if payment.registration.ChannelPoint == nil {
 
@@ -392,7 +412,7 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 			)
 			i.paymentFailure <- &paymentFailureEvent{
 				paymentId: payment.id,
-				code:      common.FAILURE_UNKNOWN_NEXT_PEER,
+				message:   common.FAILURE_UNKNOWN_NEXT_PEER,
 			}
 			return
 		}
@@ -412,7 +432,7 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 			)
 			i.paymentFailure <- &paymentFailureEvent{
 				paymentId: payment.id,
-				code:      common.FAILURE_UNKNOWN_NEXT_PEER,
+				message:   common.FAILURE_UNKNOWN_NEXT_PEER,
 			}
 			return
 		}
@@ -468,7 +488,7 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 
 			code := common.FAILURE_UNKNOWN_NEXT_PEER
 			if strings.Contains(err.Error(), "not enough funds") {
-				code = common.FAILURE_TEMPORARY_CHANNEL_FAILURE
+				code = common.FailureTemporaryChannelFailure(&chanUpdate)
 			}
 
 			// TODO: Verify that a client disconnect before receiving
@@ -479,7 +499,7 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 			// temporary_channel_failure should be returned.
 			i.paymentFailure <- &paymentFailureEvent{
 				paymentId: payment.id,
-				code:      code,
+				message:   code,
 			}
 			return
 		}
@@ -502,7 +522,7 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 			)
 			i.paymentFailure <- &paymentFailureEvent{
 				paymentId: payment.id,
-				code:      common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+				message:   common.FailureTemporaryChannelFailure(&chanUpdate),
 			}
 			return
 		}
@@ -524,7 +544,7 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 			case <-time.After(time.Until(deadline)):
 				i.paymentFailure <- &paymentFailureEvent{
 					paymentId: payment.id,
-					code:      common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+					message:   common.FailureTemporaryChannelFailure(&chanUpdate),
 				}
 				return
 			}
@@ -603,11 +623,22 @@ func (i *Interceptor) handlePaymentChanOpened(event *paymentChanOpenedEvent) {
 			event.paymentId,
 			feeRemainingMsat,
 		)
+
+		peerid, _ := hex.DecodeString(payment.registration.PeerId)
+		chanUpdate := common.ConstructChanUpdate(
+			i.config.ChainHash,
+			i.config.NodeId,
+			peerid,
+			payment.fakeScid,
+			uint16(i.config.TimeLockDelta),
+			i.config.HtlcMinimumMsat,
+			payment.paymentSizeMsat,
+		)
 		// TODO: Verify temporary_channel_failure is the way to go here, maybe
 		// unknown_next_peer is more appropriate.
 		i.paymentFailure <- &paymentFailureEvent{
 			paymentId: event.paymentId,
-			code:      common.FAILURE_TEMPORARY_CHANNEL_FAILURE,
+			message:   common.FailureTemporaryChannelFailure(&chanUpdate),
 		}
 		return
 	}

lsps2/intercept_test.go

@@ -322,7 +322,7 @@ func Test_NoMpp_CltvDeltaBelowMinimum(t *testing.T) {
 
 	res := i.Intercept(createPart(&part{cltvDelta: 145}))
 	assert.Equal(t, common.INTERCEPT_FAIL_HTLC_WITH_CODE, res.Action)
-	assert.ElementsMatch(t, common.FAILURE_INCORRECT_CLTV_EXPIRY, res.FailureMessage)
+	assert.ElementsMatch(t, common.FAILURE_INCORRECT_CLTV_EXPIRY, res.FailureMessage[:2])
 	assertEmpty(t, i)
 }
 
@@ -408,7 +408,7 @@ func Test_Mpp_SinglePart_AmtTooSmall(t *testing.T) {
 	res := i.Intercept(createPart(&part{amt: defaultPaymentSizeMsat - 1}))
 	end := time.Now()
 	assert.Equal(t, common.INTERCEPT_FAIL_HTLC_WITH_CODE, res.Action)
-	assert.ElementsMatch(t, common.FAILURE_TEMPORARY_CHANNEL_FAILURE, res.FailureMessage)
+	assert.ElementsMatch(t, common.FAILURE_TEMPORARY_CHANNEL_FAILURE, res.FailureMessage[:2])
 	assert.GreaterOrEqual(t, end.Sub(start).Milliseconds(), config.MppTimeout.Milliseconds())
 	assertEmpty(t, i)
 }
@@ -541,7 +541,7 @@ func Test_Mpp_CltvDeltaBelowMinimum(t *testing.T) {
 
 	res := i.Intercept(createPart(&part{cltvDelta: 145}))
 	assert.Equal(t, common.INTERCEPT_FAIL_HTLC_WITH_CODE, res.Action)
-	assert.ElementsMatch(t, common.FAILURE_INCORRECT_CLTV_EXPIRY, res.FailureMessage)
+	assert.ElementsMatch(t, common.FAILURE_INCORRECT_CLTV_EXPIRY, res.FailureMessage[:2])
 	assertEmpty(t, i)
 }