Merge pull request #3594 from joostjager/resolver-onion-decode

cnct: decode onion for incoming contest resolver

contractcourt/briefcase_test.go

@@ -161,9 +161,9 @@ func assertResolversEqual(t *testing.T, originalResolver ContractResolver,
 			t.Fatalf("expected %v, got %v",
 				ogRes.broadcastHeight, diskRes.broadcastHeight)
 		}
-		if ogRes.htlcIndex != diskRes.htlcIndex {
+		if ogRes.htlc.HtlcIndex != diskRes.htlc.HtlcIndex {
-			t.Fatalf("expected %v, got %v", ogRes.htlcIndex,
+			t.Fatalf("expected %v, got %v", ogRes.htlc.HtlcIndex,
-				diskRes.htlcIndex)
+				diskRes.htlc.HtlcIndex)
 		}
 	}
 
@@ -184,9 +184,9 @@ func assertResolversEqual(t *testing.T, originalResolver ContractResolver,
 			t.Fatalf("expected %v, got %v",
 				ogRes.broadcastHeight, diskRes.broadcastHeight)
 		}
-		if ogRes.payHash != diskRes.payHash {
+		if ogRes.htlc.RHash != diskRes.htlc.RHash {
-			t.Fatalf("expected %v, got %v", ogRes.payHash,
+			t.Fatalf("expected %v, got %v", ogRes.htlc.RHash,
-				diskRes.payHash)
+				diskRes.htlc.RHash)
 		}
 	}
 
@@ -265,7 +265,9 @@ func TestContractInsertionRetrieval(t *testing.T) {
 		outputIncubating: true,
 		resolved:         true,
 		broadcastHeight:  102,
-		htlcIndex:        12,
+		htlc: channeldb.HTLC{
+			HtlcIndex: 12,
+		},
 	}
 	successResolver := htlcSuccessResolver{
 		htlcResolution: lnwallet.IncomingHtlcResolution{
@@ -278,8 +280,10 @@ func TestContractInsertionRetrieval(t *testing.T) {
 		outputIncubating: true,
 		resolved:         true,
 		broadcastHeight:  109,
-		payHash:          testPreimage,
+		htlc: channeldb.HTLC{
-		sweepTx:          nil,
+			RHash: testPreimage,
+		},
+		sweepTx: nil,
 	}
 	resolvers := []ContractResolver{
 		&timeoutResolver,
@@ -395,7 +399,9 @@ func TestContractResolution(t *testing.T) {
 		outputIncubating: true,
 		resolved:         true,
 		broadcastHeight:  192,
-		htlcIndex:        9912,
+		htlc: channeldb.HTLC{
+			HtlcIndex: 9912,
+		},
 	}
 
 	// First, we'll insert the resolver into the database and ensure that
@@ -454,7 +460,9 @@ func TestContractSwapping(t *testing.T) {
 		outputIncubating: true,
 		resolved:         true,
 		broadcastHeight:  102,
-		htlcIndex:        12,
+		htlc: channeldb.HTLC{
+			HtlcIndex: 12,
+		},
 	}
 	contestResolver := &htlcOutgoingContestResolver{
 		htlcTimeoutResolver: timeoutResolver,

contractcourt/chain_arbitrator.go

@@ -151,6 +151,10 @@ type ChainArbitratorConfig struct {
 	// NotifyClosedChannel is a function closure that the ChainArbitrator
 	// will use to notify the ChannelNotifier about a newly closed channel.
 	NotifyClosedChannel func(wire.OutPoint)
+
+	// OnionProcessor is used to decode onion payloads for on-chain
+	// resolution.
+	OnionProcessor OnionProcessor
 }
 
 // ChainArbitrator is a sub-system that oversees the on-chain resolution of all

contractcourt/channel_arbitrator.go

@@ -501,9 +501,20 @@ func (c *ChannelArbitrator) relaunchResolvers(commitSet *CommitSet) error {
 		"resolvers", c.cfg.ChanPoint, len(unresolvedContracts))
 
 	for _, resolver := range unresolvedContracts {
-		if err := c.supplementResolver(resolver, htlcMap); err != nil {
+		htlcResolver, ok := resolver.(htlcContractResolver)
-			return err
+		if !ok {
+			continue
 		}
+
+		htlcPoint := htlcResolver.HtlcPoint()
+		htlc, ok := htlcMap[htlcPoint]
+		if !ok {
+			return fmt.Errorf(
+				"htlc resolver %T unavailable", resolver,
+			)
+		}
+
+		htlcResolver.Supplement(*htlc)
 	}
 
 	c.launchResolvers(unresolvedContracts)
@@ -511,89 +522,6 @@ func (c *ChannelArbitrator) relaunchResolvers(commitSet *CommitSet) error {
 	return nil
 }
 
-// supplementResolver takes a resolver as it is restored from the log and fills
-// in missing data from the htlcMap.
-func (c *ChannelArbitrator) supplementResolver(resolver ContractResolver,
-	htlcMap map[wire.OutPoint]*channeldb.HTLC) error {
-
-	switch r := resolver.(type) {
-
-	case *htlcSuccessResolver:
-		return c.supplementSuccessResolver(r, htlcMap)
-
-	case *htlcIncomingContestResolver:
-		return c.supplementIncomingContestResolver(r, htlcMap)
-
-	case *htlcTimeoutResolver:
-		return c.supplementTimeoutResolver(r, htlcMap)
-
-	case *htlcOutgoingContestResolver:
-		return c.supplementTimeoutResolver(
-			&r.htlcTimeoutResolver, htlcMap,
-		)
-	}
-
-	return nil
-}
-
-// supplementSuccessResolver takes a htlcIncomingContestResolver as it is
-// restored from the log and fills in missing data from the htlcMap.
-func (c *ChannelArbitrator) supplementIncomingContestResolver(
-	r *htlcIncomingContestResolver,
-	htlcMap map[wire.OutPoint]*channeldb.HTLC) error {
-
-	res := r.htlcResolution
-	htlcPoint := res.HtlcPoint()
-	htlc, ok := htlcMap[htlcPoint]
-	if !ok {
-		return errors.New(
-			"htlc for incoming contest resolver unavailable",
-		)
-	}
-
-	r.htlcAmt = htlc.Amt
-	r.circuitKey = channeldb.CircuitKey{
-		ChanID: c.cfg.ShortChanID,
-		HtlcID: htlc.HtlcIndex,
-	}
-
-	return nil
-}
-
-// supplementSuccessResolver takes a htlcSuccessResolver as it is restored from
-// the log and fills in missing data from the htlcMap.
-func (c *ChannelArbitrator) supplementSuccessResolver(r *htlcSuccessResolver,
-	htlcMap map[wire.OutPoint]*channeldb.HTLC) error {
-
-	res := r.htlcResolution
-	htlcPoint := res.HtlcPoint()
-	htlc, ok := htlcMap[htlcPoint]
-	if !ok {
-		return errors.New(
-			"htlc for success resolver unavailable",
-		)
-	}
-	r.htlcAmt = htlc.Amt
-	return nil
-}
-
-// supplementTimeoutResolver takes a htlcSuccessResolver as it is restored from
-// the log and fills in missing data from the htlcMap.
-func (c *ChannelArbitrator) supplementTimeoutResolver(r *htlcTimeoutResolver,
-	htlcMap map[wire.OutPoint]*channeldb.HTLC) error {
-
-	res := r.htlcResolution
-	htlcPoint := res.HtlcPoint()
-	htlc, ok := htlcMap[htlcPoint]
-	if !ok {
-		return errors.New(
-			"htlc for timeout resolver unavailable",
-		)
-	}
-	r.htlcAmt = htlc.Amt
-	return nil
-}
-
 // Report returns htlc reports for the active resolvers.
 func (c *ChannelArbitrator) Report() []*ContractReport {
 	c.activeResolversLock.RLock()
@@ -1224,8 +1152,10 @@ func (c *ChannelArbitrator) checkCommitChainActions(height uint32,
 	//  * race condition if adding and we broadcast, etc
 	//  * or would make each instance sync?
 
-	log.Debugf("ChannelArbitrator(%v): checking chain actions at "+
+	log.Debugf("ChannelArbitrator(%v): checking commit chain actions at "+
-		"height=%v", c.cfg.ChanPoint, height)
+		"height=%v, in_htlc_count=%v, out_htlc_count=%v",
+		c.cfg.ChanPoint, height,
+		len(htlcs.incomingHTLCs), len(htlcs.outgoingHTLCs))
 
 	actionMap := make(ChainActionMap)
 
@@ -1719,6 +1649,8 @@ func (c *ChannelArbitrator) prepContractResolutions(
 		// claim the HTLC (second-level or directly), then add the pre
 		case HtlcClaimAction:
 			for _, htlc := range htlcs {
+				htlc := htlc
+
 				htlcOp := wire.OutPoint{
 					Hash:  commitHash,
 					Index: uint32(htlc.OutputIndex),
@@ -1734,8 +1666,7 @@ func (c *ChannelArbitrator) prepContractResolutions(
 				}
 
 				resolver := newSuccessResolver(
-					resolution, height,
+					resolution, height, htlc, resolverCfg,
-					htlc.RHash, htlc.Amt, resolverCfg,
 				)
 				htlcResolvers = append(htlcResolvers, resolver)
 			}
@@ -1745,6 +1676,8 @@ func (c *ChannelArbitrator) prepContractResolutions(
 		// backwards.
 		case HtlcTimeoutAction:
 			for _, htlc := range htlcs {
+				htlc := htlc
+
 				htlcOp := wire.OutPoint{
 					Hash:  commitHash,
 					Index: uint32(htlc.OutputIndex),
@@ -1758,8 +1691,7 @@ func (c *ChannelArbitrator) prepContractResolutions(
 				}
 
 				resolver := newTimeoutResolver(
-					resolution, height, htlc.HtlcIndex,
+					resolution, height, htlc, resolverCfg,
-					htlc.Amt, resolverCfg,
 				)
 				htlcResolvers = append(htlcResolvers, resolver)
 			}
@@ -1769,6 +1701,8 @@ func (c *ChannelArbitrator) prepContractResolutions(
 		// learn of the pre-image, or let the remote party time out.
 		case HtlcIncomingWatchAction:
 			for _, htlc := range htlcs {
+				htlc := htlc
+
 				htlcOp := wire.OutPoint{
 					Hash:  commitHash,
 					Index: uint32(htlc.OutputIndex),
@@ -1785,15 +1719,9 @@ func (c *ChannelArbitrator) prepContractResolutions(
 					continue
 				}
 
-				circuitKey := channeldb.CircuitKey{
-					HtlcID: htlc.HtlcIndex,
-					ChanID: c.cfg.ShortChanID,
-				}
-
 				resolver := newIncomingContestResolver(
-					htlc.RefundTimeout, circuitKey,
+					resolution, height, htlc,
-					resolution, height, htlc.RHash,
+					resolverCfg,
-					htlc.Amt, resolverCfg,
 				)
 				htlcResolvers = append(htlcResolvers, resolver)
 			}
@@ -1803,6 +1731,8 @@ func (c *ChannelArbitrator) prepContractResolutions(
 		// backwards), or just timeout.
 		case HtlcOutgoingWatchAction:
 			for _, htlc := range htlcs {
+				htlc := htlc
+
 				htlcOp := wire.OutPoint{
 					Hash:  commitHash,
 					Index: uint32(htlc.OutputIndex),
@@ -1817,8 +1747,7 @@ func (c *ChannelArbitrator) prepContractResolutions(
 				}
 
 				resolver := newOutgoingContestResolver(
-					resolution, height, htlc.HtlcIndex,
+					resolution, height, htlc, resolverCfg,
-					htlc.Amt, resolverCfg,
 				)
 				htlcResolvers = append(htlcResolvers, resolver)
 			}

contractcourt/channel_arbitrator_test.go

@@ -308,6 +308,7 @@ func createTestChannelArbitrator(t *testing.T, log ArbitratorLog) (*chanArbTestC
 			incubateChan <- struct{}{}
 			return nil
 		},
+		OnionProcessor: &mockOnionProcessor{},
 	}
 
 	// We'll use the resolvedChan to synchronize on call to
@@ -858,10 +859,10 @@ func TestChannelArbitratorLocalForceClosePendingHtlc(t *testing.T) {
 			resolver)
 	}
 
-	// The resolver should have its htlcAmt field populated as it.
+	// The resolver should have its htlc amt field populated as it.
-	if int64(outgoingResolver.htlcAmt) != int64(htlcAmt) {
+	if int64(outgoingResolver.htlc.Amt) != int64(htlcAmt) {
 		t.Fatalf("wrong htlc amount: expected %v, got %v,",
-			htlcAmt, int64(outgoingResolver.htlcAmt))
+			htlcAmt, int64(outgoingResolver.htlc.Amt))
 	}
 
 	// htlcOutgoingContestResolver is now active and waiting for the HTLC to

contractcourt/contract_resolvers.go

@@ -4,6 +4,9 @@ import (
 	"encoding/binary"
 	"errors"
 	"io"
+
+	"github.com/btcsuite/btcd/wire"
+	"github.com/lightningnetwork/lnd/channeldb"
 )
 
 var (
@@ -51,6 +54,18 @@ type ContractResolver interface {
 	Stop()
 }
 
+// htlcContractResolver is the required interface for htlc resolvers.
+type htlcContractResolver interface {
+	ContractResolver
+
+	// HtlcPoint returns the htlc's outpoint on the commitment tx.
+	HtlcPoint() wire.OutPoint
+
+	// Supplement adds additional information to the resolver that is
+	// required before Resolve() is called.
+	Supplement(htlc channeldb.HTLC)
+}
+
 // reportingContractResolver is a ContractResolver that also exposes a report on
 // the resolution state of the contract.
 type reportingContractResolver interface {

contractcourt/htlc_incoming_contest_resolver.go

@@ -1,16 +1,17 @@
 package contractcourt
 
 import (
+	"bytes"
 	"encoding/binary"
 	"errors"
 	"io"
 
 	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/htlcswitch/hop"
 	"github.com/lightningnetwork/lnd/invoices"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet"
-	"github.com/lightningnetwork/lnd/lnwire"
 )
 
 // htlcIncomingContestResolver is a ContractResolver that's able to resolve an
@@ -27,28 +28,22 @@ type htlcIncomingContestResolver struct {
 	// successfully.
 	htlcExpiry uint32
 
-	// circuitKey describes the incoming htlc that is being resolved.
-	circuitKey channeldb.CircuitKey
-
 	// htlcSuccessResolver is the inner resolver that may be utilized if we
 	// learn of the preimage.
 	htlcSuccessResolver
 }
 
 // newIncomingContestResolver instantiates a new incoming htlc contest resolver.
-func newIncomingContestResolver(htlcExpiry uint32,
+func newIncomingContestResolver(
-	circuitKey channeldb.CircuitKey, res lnwallet.IncomingHtlcResolution,
+	res lnwallet.IncomingHtlcResolution, broadcastHeight uint32,
-	broadcastHeight uint32, payHash lntypes.Hash,
+	htlc channeldb.HTLC, resCfg ResolverConfig) *htlcIncomingContestResolver {
-	htlcAmt lnwire.MilliSatoshi,
-	resCfg ResolverConfig) *htlcIncomingContestResolver {
 
 	success := newSuccessResolver(
-		res, broadcastHeight, payHash, htlcAmt, resCfg,
+		res, broadcastHeight, htlc, resCfg,
 	)
 
 	return &htlcIncomingContestResolver{
-		htlcExpiry:          htlcExpiry,
+		htlcExpiry:          htlc.RefundTimeout,
-		circuitKey:          circuitKey,
 		htlcSuccessResolver: *success,
 	}
 }
@@ -72,6 +67,22 @@ func (h *htlcIncomingContestResolver) Resolve() (ContractResolver, error) {
 		return nil, nil
 	}
 
+	// First try to parse the payload. If that fails, we can stop resolution
+	// now.
+	payload, err := h.decodePayload()
+	if err != nil {
+		log.Debugf("ChannelArbitrator(%v): cannot decode payload of "+
+			"htlc %v", h.ChanPoint, h.HtlcPoint())
+
+		// If we've locked in an htlc with an invalid payload on our
+		// commitment tx, we don't need to resolve it. The other party
+		// will time it out and get their funds back. This situation can
+		// present itself when we crash before processRemoteAdds in the
+		// link has ran.
+		h.resolved = true
+		return nil, nil
+	}
+
 	// Register for block epochs. After registration, the current height
 	// will be sent on the channel immediately.
 	blockEpochs, err := h.Notifier.RegisterBlockEpochNtfn(nil)
@@ -119,7 +130,7 @@ func (h *htlcIncomingContestResolver) Resolve() (ContractResolver, error) {
 	applyPreimage := func(preimage lntypes.Preimage) error {
 		// Sanity check to see if this preimage matches our htlc. At
 		// this point it should never happen that it does not match.
-		if !preimage.Matches(h.payHash) {
+		if !preimage.Matches(h.htlc.RHash) {
 			return errors.New("preimage does not match hash")
 		}
 
@@ -185,9 +196,14 @@ func (h *htlcIncomingContestResolver) Resolve() (ContractResolver, error) {
 	// on-chain. If this HTLC indeed pays to an existing invoice, the
 	// invoice registry will tell us what to do with the HTLC. This is
 	// identical to HTLC resolution in the link.
+	circuitKey := channeldb.CircuitKey{
+		ChanID: h.ShortChanID,
+		HtlcID: h.htlc.HtlcIndex,
+	}
+
 	event, err := h.Registry.NotifyExitHopHtlc(
-		h.payHash, h.htlcAmt, h.htlcExpiry, currentHeight,
+		h.htlc.RHash, h.htlc.Amt, h.htlcExpiry, currentHeight,
-		h.circuitKey, hodlChan, nil,
+		circuitKey, hodlChan, payload,
 	)
 	switch err {
 	case channeldb.ErrInvoiceNotFound:
@@ -204,7 +220,7 @@ func (h *htlcIncomingContestResolver) Resolve() (ContractResolver, error) {
 
 	// With the epochs and preimage subscriptions initialized, we'll query
 	// to see if we already know the preimage.
-	preimage, ok := h.PreimageDB.LookupPreimage(h.payHash)
+	preimage, ok := h.PreimageDB.LookupPreimage(h.htlc.RHash)
 	if ok {
 		// If we do, then this means we can claim the HTLC!  However,
 		// we don't know how to ourselves, so we'll return our inner
@@ -222,7 +238,7 @@ func (h *htlcIncomingContestResolver) Resolve() (ContractResolver, error) {
 		case preimage := <-preimageSubscription.WitnessUpdates:
 			// We receive all new preimages, so we need to ignore
 			// all except the preimage we are waiting for.
-			if !preimage.Matches(h.payHash) {
+			if !preimage.Matches(h.htlc.RHash) {
 				continue
 			}
 
@@ -268,7 +284,7 @@ func (h *htlcIncomingContestResolver) Resolve() (ContractResolver, error) {
 func (h *htlcIncomingContestResolver) report() *ContractReport {
 	// No locking needed as these values are read-only.
 
-	finalAmt := h.htlcAmt.ToSatoshis()
+	finalAmt := h.htlc.Amt.ToSatoshis()
 	if h.htlcResolution.SignedSuccessTx != nil {
 		finalAmt = btcutil.Amount(
 			h.htlcResolution.SignedSuccessTx.TxOut[0].Value,
@@ -338,6 +354,28 @@ func newIncomingContestResolverFromReader(r io.Reader, resCfg ResolverConfig) (
 	return h, nil
 }
 
+// Supplement adds additional information to the resolver that is required
+// before Resolve() is called.
+//
+// NOTE: Part of the htlcContractResolver interface.
+func (h *htlcIncomingContestResolver) Supplement(htlc channeldb.HTLC) {
+	h.htlc = htlc
+}
+
+// decodePayload (re)decodes the hop payload of a received htlc.
+func (h *htlcIncomingContestResolver) decodePayload() (*hop.Payload, error) {
+
+	onionReader := bytes.NewReader(h.htlc.OnionBlob)
+	iterator, err := h.OnionProcessor.ReconstructHopIterator(
+		onionReader, h.htlc.RHash[:],
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return iterator.HopPayload()
+}
+
 // A compile time assertion to ensure htlcIncomingContestResolver meets the
 // ContractResolver interface.
-var _ ContractResolver = (*htlcIncomingContestResolver)(nil)
+var _ htlcContractResolver = (*htlcIncomingContestResolver)(nil)

contractcourt/htlc_incoming_resolver_test.go

@@ -2,9 +2,12 @@ package contractcourt
 
 import (
 	"bytes"
+	"io"
+	"io/ioutil"
 	"testing"
 
 	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/htlcswitch/hop"
 	"github.com/lightningnetwork/lnd/invoices"
 	"github.com/lightningnetwork/lnd/lnwallet"
 
@@ -21,6 +24,7 @@ var (
 	testResPreimage   = lntypes.Preimage{1, 2, 3}
 	testResHash       = testResPreimage.Hash()
 	testResCircuitKey = channeldb.CircuitKey{}
+	testOnionBlob     = []byte{4, 5, 6}
 )
 
 // TestHtlcIncomingResolverFwdPreimageKnown tests resolution of a forwarded htlc
@@ -107,6 +111,12 @@ func TestHtlcIncomingResolverExitSettle(t *testing.T) {
 	}
 
 	ctx.waitForResult(true)
+
+	if !bytes.Equal(
+		ctx.onionProcessor.offeredOnionBlob, testOnionBlob,
+	) {
+		t.Fatal("unexpected onion blob")
+	}
 }
 
 // TestHtlcIncomingResolverExitCancel tests resolution of an exit hop htlc for
@@ -168,14 +178,39 @@ func TestHtlcIncomingResolverExitCancelHodl(t *testing.T) {
 	ctx.waitForResult(false)
 }
 
+type mockHopIterator struct {
+	hop.Iterator
+}
+
+func (h *mockHopIterator) HopPayload() (*hop.Payload, error) {
+	return nil, nil
+}
+
+type mockOnionProcessor struct {
+	offeredOnionBlob []byte
+}
+
+func (o *mockOnionProcessor) ReconstructHopIterator(r io.Reader, rHash []byte) (
+	hop.Iterator, error) {
+
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+	o.offeredOnionBlob = data
+
+	return &mockHopIterator{}, nil
+}
+
 type incomingResolverTestContext struct {
-	registry      *mockRegistry
+	registry       *mockRegistry
-	witnessBeacon *mockWitnessBeacon
+	witnessBeacon  *mockWitnessBeacon
-	resolver      *htlcIncomingContestResolver
+	resolver       *htlcIncomingContestResolver
-	notifier      *mockNotifier
+	notifier       *mockNotifier
-	resolveErr    chan error
+	onionProcessor *mockOnionProcessor
-	nextResolver  ContractResolver
+	resolveErr     chan error
-	t             *testing.T
+	nextResolver   ContractResolver
+	t              *testing.T
 }
 
 func newIncomingResolverTestContext(t *testing.T) *incomingResolverTestContext {
@@ -189,13 +224,16 @@ func newIncomingResolverTestContext(t *testing.T) *incomingResolverTestContext {
 		notifyChan: make(chan notifyExitHopData, 1),
 	}
 
+	onionProcessor := &mockOnionProcessor{}
+
 	checkPointChan := make(chan struct{}, 1)
 
 	chainCfg := ChannelArbitratorConfig{
 		ChainArbitratorConfig: ChainArbitratorConfig{
-			Notifier:   notifier,
+			Notifier:       notifier,
-			PreimageDB: witnessBeacon,
+			PreimageDB:     witnessBeacon,
-			Registry:   registry,
+			Registry:       registry,
+			OnionProcessor: onionProcessor,
 		},
 	}
 
@@ -210,17 +248,21 @@ func newIncomingResolverTestContext(t *testing.T) *incomingResolverTestContext {
 		htlcSuccessResolver: htlcSuccessResolver{
 			contractResolverKit: *newContractResolverKit(cfg),
 			htlcResolution:      lnwallet.IncomingHtlcResolution{},
-			payHash:             testResHash,
+			htlc: channeldb.HTLC{
+				RHash:     testResHash,
+				OnionBlob: testOnionBlob,
+			},
 		},
 		htlcExpiry: testHtlcExpiry,
 	}
 
 	return &incomingResolverTestContext{
-		registry:      registry,
+		registry:       registry,
-		witnessBeacon: witnessBeacon,
+		witnessBeacon:  witnessBeacon,
-		resolver:      resolver,
+		resolver:       resolver,
-		notifier:      notifier,
+		notifier:       notifier,
-		t:             t,
+		onionProcessor: onionProcessor,
+		t:              t,
 	}
 }
 

contractcourt/htlc_outgoing_contest_resolver.go

@@ -5,8 +5,8 @@ import (
 	"io"
 
 	"github.com/btcsuite/btcutil"
+	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lnwallet"
-	"github.com/lightningnetwork/lnd/lnwire"
 )
 
 // htlcOutgoingContestResolver is a ContractResolver that's able to resolve an
@@ -23,11 +23,11 @@ type htlcOutgoingContestResolver struct {
 // newOutgoingContestResolver instantiates a new outgoing contested htlc
 // resolver.
 func newOutgoingContestResolver(res lnwallet.OutgoingHtlcResolution,
-	broadcastHeight uint32, htlcIndex uint64, htlcAmt lnwire.MilliSatoshi,
+	broadcastHeight uint32, htlc channeldb.HTLC,
 	resCfg ResolverConfig) *htlcOutgoingContestResolver {
 
 	timeout := newTimeoutResolver(
-		res, broadcastHeight, htlcIndex, htlcAmt, resCfg,
+		res, broadcastHeight, htlc, resCfg,
 	)
 
 	return &htlcOutgoingContestResolver{
@@ -157,7 +157,7 @@ func (h *htlcOutgoingContestResolver) Resolve() (ContractResolver, error) {
 func (h *htlcOutgoingContestResolver) report() *ContractReport {
 	// No locking needed as these values are read-only.
 
-	finalAmt := h.htlcAmt.ToSatoshis()
+	finalAmt := h.htlc.Amt.ToSatoshis()
 	if h.htlcResolution.SignedTimeoutTx != nil {
 		finalAmt = btcutil.Amount(
 			h.htlcResolution.SignedTimeoutTx.TxOut[0].Value,
@@ -215,4 +215,4 @@ func newOutgoingContestResolverFromReader(r io.Reader, resCfg ResolverConfig) (
 
 // A compile time assertion to ensure htlcOutgoingContestResolver meets the
 // ContractResolver interface.
-var _ ContractResolver = (*htlcOutgoingContestResolver)(nil)
+var _ htlcContractResolver = (*htlcOutgoingContestResolver)(nil)

contractcourt/htlc_outgoing_contest_resolver_test.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet"
@@ -98,6 +99,8 @@ func newOutgoingResolverTestContext(t *testing.T) *outgoingResolverTestContext {
 
 	preimageDB := newMockWitnessBeacon()
 
+	onionProcessor := &mockOnionProcessor{}
+
 	chainCfg := ChannelArbitratorConfig{
 		ChainArbitratorConfig: ChainArbitratorConfig{
 			Notifier:   notifier,
@@ -112,6 +115,7 @@ func newOutgoingResolverTestContext(t *testing.T) *outgoingResolverTestContext {
 				resolutionChan <- msgs[0]
 				return nil
 			},
+			OnionProcessor: onionProcessor,
 		},
 	}
 
@@ -134,6 +138,10 @@ func newOutgoingResolverTestContext(t *testing.T) *outgoingResolverTestContext {
 		htlcTimeoutResolver: htlcTimeoutResolver{
 			contractResolverKit: *newContractResolverKit(cfg),
 			htlcResolution:      outgoingRes,
+			htlc: channeldb.HTLC{
+				RHash:     testResHash,
+				OnionBlob: testOnionBlob,
+			},
 		},
 	}
 

contractcourt/htlc_success_resolver.go

@@ -6,10 +6,9 @@ import (
 
 	"github.com/btcsuite/btcd/wire"
 	"github.com/davecgh/go-spew/spew"
+	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/input"
-	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet"
-	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/sweep"
 )
 
@@ -38,9 +37,6 @@ type htlcSuccessResolver struct {
 	// historical queries to the chain for spends/confirmations.
 	broadcastHeight uint32
 
-	// payHash is the payment hash of the original HTLC extended to us.
-	payHash lntypes.Hash
-
 	// sweepTx will be non-nil if we've already crafted a transaction to
 	// sweep a direct HTLC output. This is only a concern if we're sweeping
 	// from the commitment transaction of the remote party.
@@ -48,25 +44,22 @@ type htlcSuccessResolver struct {
 	// TODO(roasbeef): send off to utxobundler
 	sweepTx *wire.MsgTx
 
-	// htlcAmt is the original amount of the htlc, not taking into
+	// htlc contains information on the htlc that we are resolving on-chain.
-	// account any fees that may have to be paid if it goes on chain.
+	htlc channeldb.HTLC
-	htlcAmt lnwire.MilliSatoshi
 
 	contractResolverKit
 }
 
 // newSuccessResolver instanties a new htlc success resolver.
 func newSuccessResolver(res lnwallet.IncomingHtlcResolution,
-	broadcastHeight uint32, payHash lntypes.Hash,
+	broadcastHeight uint32, htlc channeldb.HTLC,
-	htlcAmt lnwire.MilliSatoshi,
 	resCfg ResolverConfig) *htlcSuccessResolver {
 
 	return &htlcSuccessResolver{
 		contractResolverKit: *newContractResolverKit(resCfg),
 		htlcResolution:      res,
 		broadcastHeight:     broadcastHeight,
-		payHash:             payHash,
+		htlc:                htlc,
-		htlcAmt:             htlcAmt,
 	}
 }
 
@@ -114,7 +107,7 @@ func (h *htlcSuccessResolver) Resolve() (ContractResolver, error) {
 		if h.sweepTx == nil {
 			log.Infof("%T(%x): crafting sweep tx for "+
 				"incoming+remote htlc confirmed", h,
-				h.payHash[:])
+				h.htlc.RHash[:])
 
 			// Before we can craft out sweeping transaction, we
 			// need to create an input which contains all the items
@@ -148,7 +141,7 @@ func (h *htlcSuccessResolver) Resolve() (ContractResolver, error) {
 			}
 
 			log.Infof("%T(%x): crafted sweep tx=%v", h,
-				h.payHash[:], spew.Sdump(h.sweepTx))
+				h.htlc.RHash[:], spew.Sdump(h.sweepTx))
 
 			// With the sweep transaction signed, we'll now
 			// Checkpoint our state.
@@ -164,7 +157,7 @@ func (h *htlcSuccessResolver) Resolve() (ContractResolver, error) {
 		err := h.PublishTx(h.sweepTx)
 		if err != nil {
 			log.Infof("%T(%x): unable to publish tx: %v",
-				h, h.payHash[:], err)
+				h, h.htlc.RHash[:], err)
 			return nil, err
 		}
 
@@ -180,7 +173,7 @@ func (h *htlcSuccessResolver) Resolve() (ContractResolver, error) {
 		}
 
 		log.Infof("%T(%x): waiting for sweep tx (txid=%v) to be "+
-			"confirmed", h, h.payHash[:], sweepTXID)
+			"confirmed", h, h.htlc.RHash[:], sweepTXID)
 
 		select {
 		case _, ok := <-confNtfn.Confirmed:
@@ -199,7 +192,7 @@ func (h *htlcSuccessResolver) Resolve() (ContractResolver, error) {
 	}
 
 	log.Infof("%T(%x): broadcasting second-layer transition tx: %v",
-		h, h.payHash[:], spew.Sdump(h.htlcResolution.SignedSuccessTx))
+		h, h.htlc.RHash[:], spew.Sdump(h.htlcResolution.SignedSuccessTx))
 
 	// We'll now broadcast the second layer transaction so we can kick off
 	// the claiming process.
@@ -215,7 +208,7 @@ func (h *htlcSuccessResolver) Resolve() (ContractResolver, error) {
 	// done so.
 	if !h.outputIncubating {
 		log.Infof("%T(%x): incubating incoming htlc output",
-			h, h.payHash[:])
+			h, h.htlc.RHash[:])
 
 		err := h.IncubateOutputs(
 			h.ChanPoint, nil, nil, &h.htlcResolution,
@@ -245,7 +238,7 @@ func (h *htlcSuccessResolver) Resolve() (ContractResolver, error) {
 	}
 
 	log.Infof("%T(%x): waiting for second-level HTLC output to be spent "+
-		"after csv_delay=%v", h, h.payHash[:], h.htlcResolution.CsvDelay)
+		"after csv_delay=%v", h, h.htlc.RHash[:], h.htlcResolution.CsvDelay)
 
 	select {
 	case _, ok := <-spendNtfn.Spend:
@@ -298,7 +291,7 @@ func (h *htlcSuccessResolver) Encode(w io.Writer) error {
 	if err := binary.Write(w, endian, h.broadcastHeight); err != nil {
 		return err
 	}
-	if _, err := w.Write(h.payHash[:]); err != nil {
+	if _, err := w.Write(h.htlc.RHash[:]); err != nil {
 		return err
 	}
 
@@ -331,13 +324,28 @@ func newSuccessResolverFromReader(r io.Reader, resCfg ResolverConfig) (
 	if err := binary.Read(r, endian, &h.broadcastHeight); err != nil {
 		return nil, err
 	}
-	if _, err := io.ReadFull(r, h.payHash[:]); err != nil {
+	if _, err := io.ReadFull(r, h.htlc.RHash[:]); err != nil {
 		return nil, err
 	}
 
 	return h, nil
 }
 
+// Supplement adds additional information to the resolver that is required
+// before Resolve() is called.
+//
+// NOTE: Part of the htlcContractResolver interface.
+func (h *htlcSuccessResolver) Supplement(htlc channeldb.HTLC) {
+	h.htlc = htlc
+}
+
+// HtlcPoint returns the htlc's outpoint on the commitment tx.
+//
+// NOTE: Part of the htlcContractResolver interface.
+func (h *htlcSuccessResolver) HtlcPoint() wire.OutPoint {
+	return h.htlcResolution.HtlcPoint()
+}
+
 // A compile time assertion to ensure htlcSuccessResolver meets the
 // ContractResolver interface.
-var _ ContractResolver = (*htlcSuccessResolver)(nil)
+var _ htlcContractResolver = (*htlcSuccessResolver)(nil)

contractcourt/htlc_timeout_resolver.go

@@ -8,6 +8,7 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet"
@@ -40,29 +41,22 @@ type htlcTimeoutResolver struct {
 	// TODO(roasbeef): wrap above into definite resolution embedding?
 	broadcastHeight uint32
 
-	// htlcIndex is the index of this HTLC within the trace of the
+	// htlc contains information on the htlc that we are resolving on-chain.
-	// additional commitment state machine.
+	htlc channeldb.HTLC
-	htlcIndex uint64
-
-	// htlcAmt is the original amount of the htlc, not taking into
-	// account any fees that may have to be paid if it goes on chain.
-	htlcAmt lnwire.MilliSatoshi
 
 	contractResolverKit
 }
 
 // newTimeoutResolver instantiates a new timeout htlc resolver.
 func newTimeoutResolver(res lnwallet.OutgoingHtlcResolution,
-	broadcastHeight uint32, htlcIndex uint64,
+	broadcastHeight uint32, htlc channeldb.HTLC,
-	htlcAmt lnwire.MilliSatoshi,
 	resCfg ResolverConfig) *htlcTimeoutResolver {
 
 	return &htlcTimeoutResolver{
 		contractResolverKit: *newContractResolverKit(resCfg),
 		htlcResolution:      res,
 		broadcastHeight:     broadcastHeight,
-		htlcIndex:           htlcIndex,
+		htlc:                htlc,
-		htlcAmt:             htlcAmt,
 	}
 }
 
@@ -157,7 +151,7 @@ func (h *htlcTimeoutResolver) claimCleanUp(
 	// resolved, then exit.
 	if err := h.DeliverResolutionMsg(ResolutionMsg{
 		SourceChan: h.ShortChanID,
-		HtlcIndex:  h.htlcIndex,
+		HtlcIndex:  h.htlc.HtlcIndex,
 		PreImage:   &pre,
 	}); err != nil {
 		return nil, err
@@ -352,7 +346,7 @@ func (h *htlcTimeoutResolver) Resolve() (ContractResolver, error) {
 	failureMsg := &lnwire.FailPermanentChannelFailure{}
 	if err := h.DeliverResolutionMsg(ResolutionMsg{
 		SourceChan: h.ShortChanID,
-		HtlcIndex:  h.htlcIndex,
+		HtlcIndex:  h.htlc.HtlcIndex,
 		Failure:    failureMsg,
 	}); err != nil {
 		return nil, err
@@ -414,7 +408,7 @@ func (h *htlcTimeoutResolver) Encode(w io.Writer) error {
 		return err
 	}
 
-	if err := binary.Write(w, endian, h.htlcIndex); err != nil {
+	if err := binary.Write(w, endian, h.htlc.HtlcIndex); err != nil {
 		return err
 	}
 
@@ -449,13 +443,28 @@ func newTimeoutResolverFromReader(r io.Reader, resCfg ResolverConfig) (
 		return nil, err
 	}
 
-	if err := binary.Read(r, endian, &h.htlcIndex); err != nil {
+	if err := binary.Read(r, endian, &h.htlc.HtlcIndex); err != nil {
 		return nil, err
 	}
 
 	return h, nil
 }
 
+// Supplement adds additional information to the resolver that is required
+// before Resolve() is called.
+//
+// NOTE: Part of the htlcContractResolver interface.
+func (h *htlcTimeoutResolver) Supplement(htlc channeldb.HTLC) {
+	h.htlc = htlc
+}
+
+// HtlcPoint returns the htlc's outpoint on the commitment tx.
+//
+// NOTE: Part of the htlcContractResolver interface.
+func (h *htlcTimeoutResolver) HtlcPoint() wire.OutPoint {
+	return h.htlcResolution.HtlcPoint()
+}
+
 // A compile time assertion to ensure htlcTimeoutResolver meets the
 // ContractResolver interface.
-var _ ContractResolver = (*htlcTimeoutResolver)(nil)
+var _ htlcContractResolver = (*htlcTimeoutResolver)(nil)

contractcourt/interfaces.go

@@ -1,7 +1,10 @@
 package contractcourt
 
 import (
+	"io"
+
 	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/htlcswitch/hop"
 	"github.com/lightningnetwork/lnd/invoices"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
@@ -26,3 +29,10 @@ type Registry interface {
 	// HodlUnsubscribeAll unsubscribes from all hodl events.
 	HodlUnsubscribeAll(subscriber chan<- interface{})
 }
+
+// OnionProcessor is an interface used to decode onion blobs.
+type OnionProcessor interface {
+	// ReconstructHopIterator attempts to decode a valid sphinx packet from
+	// the passed io.Reader instance.
+	ReconstructHopIterator(r io.Reader, rHash []byte) (hop.Iterator, error)
+}

htlcswitch/hop/iterator.go

@@ -184,6 +184,30 @@ func (p *OnionProcessor) DecodeHopIterator(r io.Reader, rHash []byte,
 	return makeSphinxHopIterator(onionPkt, sphinxPacket), lnwire.CodeNone
 }
 
+// ReconstructHopIterator attempts to decode a valid sphinx packet from the passed io.Reader
+// instance using the rHash as the associated data when checking the relevant
+// MACs during the decoding process.
+func (p *OnionProcessor) ReconstructHopIterator(r io.Reader, rHash []byte) (
+	Iterator, error) {
+
+	onionPkt := &sphinx.OnionPacket{}
+	if err := onionPkt.Decode(r); err != nil {
+		return nil, err
+	}
+
+	// Attempt to process the Sphinx packet. We include the payment hash of
+	// the HTLC as it's authenticated within the Sphinx packet itself as
+	// associated data in order to thwart attempts a replay attacks. In the
+	// case of a replay, an attacker is *forced* to use the same payment
+	// hash twice, thereby losing their money entirely.
+	sphinxPacket, err := p.router.ReconstructOnionPacket(onionPkt, rHash)
+	if err != nil {
+		return nil, err
+	}
+
+	return makeSphinxHopIterator(onionPkt, sphinxPacket), nil
+}
+
 // DecodeHopIteratorRequest encapsulates all date necessary to process an onion
 // packet, perform sphinx replay detection, and schedule the entry for garbage
 // collection.

server.go

@@ -906,6 +906,7 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB,
 		Sweeper:             s.sweeper,
 		Registry:            s.invoices,
 		NotifyClosedChannel: s.channelNotifier.NotifyClosedChannelEvent,
+		OnionProcessor:      s.sphinx,
 	}, chanDB)
 
 	s.breachArbiter = newBreachArbiter(&BreachConfig{