cnct+htlcswitch+invoices: report circuit key to invoice registry

Currently the invoice registry cannot tell apart the htlcs that pay to
an invoice. Because htlcs may also be replayed on startup, it isn't
possible to determine the total amount paid to an invoice.

This commit is a first step towards fixing that. It reports the circuit
keys of htlcs to the invoice registry, which forms the basis for
accurate invoice accounting.

contractcourt/channel_arbitrator.go

@@ -498,9 +498,7 @@ func (c *ChannelArbitrator) supplementResolver(resolver ContractResolver,
 		return c.supplementSuccessResolver(r, htlcMap)
 
 	case *htlcIncomingContestResolver:
-		return c.supplementSuccessResolver(
-			&r.htlcSuccessResolver, htlcMap,
-		)
+		return c.supplementIncomingContestResolver(r, htlcMap)
 
 	case *htlcTimeoutResolver:
 		return c.supplementTimeoutResolver(r, htlcMap)
@@ -514,6 +512,30 @@ func (c *ChannelArbitrator) supplementResolver(resolver ContractResolver,
 	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,

contractcourt/htlc_incoming_contest_resolver.go

@@ -27,6 +27,9 @@ 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
@@ -166,7 +169,7 @@ func (h *htlcIncomingContestResolver) Resolve() (ContractResolver, error) {
 	// identical to HTLC resolution in the link.
 	event, err := h.Registry.NotifyExitHopHtlc(
 		h.payHash, h.htlcAmt, h.htlcExpiry, currentHeight,
-		hodlChan, nil,
+		h.circuitKey, hodlChan, nil,
 	)
 	switch err {
 	case channeldb.ErrInvoiceNotFound:

contractcourt/interfaces.go

@@ -22,7 +22,7 @@ type Registry interface {
 	// the resolution is sent on the passed in hodlChan later.
 	NotifyExitHopHtlc(payHash lntypes.Hash, paidAmount lnwire.MilliSatoshi,
 		expiry uint32, currentHeight int32,
-		hodlChan chan<- interface{},
+		circuitKey channeldb.CircuitKey, hodlChan chan<- interface{},
 		eob []byte) (*invoices.HodlEvent, error)
 
 	// HodlUnsubscribeAll unsubscribes from all hodl events.

contractcourt/mock_registry_test.go

@@ -23,7 +23,8 @@ type mockRegistry struct {
 
 func (r *mockRegistry) NotifyExitHopHtlc(payHash lntypes.Hash,
 	paidAmount lnwire.MilliSatoshi, expiry uint32, currentHeight int32,
-	hodlChan chan<- interface{}, eob []byte) (*invoices.HodlEvent, error) {
+	circuitKey channeldb.CircuitKey, hodlChan chan<- interface{},
+	eob []byte) (*invoices.HodlEvent, error) {
 
 	r.notifyChan <- notifyExitHopData{
 		hodlChan:      hodlChan,

htlcswitch/interfaces.go

@@ -28,7 +28,7 @@ type InvoiceDatabase interface {
 	// for decoding purposes.
 	NotifyExitHopHtlc(payHash lntypes.Hash, paidAmount lnwire.MilliSatoshi,
 		expiry uint32, currentHeight int32,
-		hodlChan chan<- interface{},
+		circuitKey channeldb.CircuitKey, hodlChan chan<- interface{},
 		eob []byte) (*invoices.HodlEvent, error)
 
 	// CancelInvoice attempts to cancel the invoice corresponding to the

htlcswitch/link.go

@@ -2878,9 +2878,14 @@ func (l *channelLink) processExitHop(pd *lnwallet.PaymentDescriptor,
 	// receive back a resolution event.
 	invoiceHash := lntypes.Hash(pd.RHash)
 
+	circuitKey := channeldb.CircuitKey{
+		ChanID: l.ShortChanID(),
+		HtlcID: pd.HtlcIndex,
+	}
+
 	event, err := l.cfg.Registry.NotifyExitHopHtlc(
 		invoiceHash, pd.Amount, pd.Timeout, int32(heightNow),
-		l.hodlQueue.ChanIn(), eob,
+		circuitKey, l.hodlQueue.ChanIn(), eob,
 	)
 
 	switch err {

htlcswitch/mock.go

@@ -793,10 +793,11 @@ func (i *mockInvoiceRegistry) SettleHodlInvoice(preimage lntypes.Preimage) error
 
 func (i *mockInvoiceRegistry) NotifyExitHopHtlc(rhash lntypes.Hash,
 	amt lnwire.MilliSatoshi, expiry uint32, currentHeight int32,
-	hodlChan chan<- interface{}, eob []byte) (*invoices.HodlEvent, error) {
+	circuitKey channeldb.CircuitKey, hodlChan chan<- interface{},
+	eob []byte) (*invoices.HodlEvent, error) {
 
 	event, err := i.registry.NotifyExitHopHtlc(
-		rhash, amt, expiry, currentHeight, hodlChan, eob,
+		rhash, amt, expiry, currentHeight, circuitKey, hodlChan, eob,
 	)
 	if err != nil {
 		return nil, err

invoices/invoiceregistry.go

@@ -484,14 +484,15 @@ func (i *InvoiceRegistry) checkHtlcParameters(invoice *channeldb.Invoice,
 // prevent deadlock.
 func (i *InvoiceRegistry) NotifyExitHopHtlc(rHash lntypes.Hash,
 	amtPaid lnwire.MilliSatoshi, expiry uint32, currentHeight int32,
-	hodlChan chan<- interface{}, eob []byte) (*HodlEvent, error) {
+	circuitKey channeldb.CircuitKey, hodlChan chan<- interface{},
+	eob []byte) (*HodlEvent, error) {
 
 	i.Lock()
 	defer i.Unlock()
 
 	debugLog := func(s string) {
-		log.Debugf("Invoice(%x): %v, amt=%v, expiry=%v",
-			rHash[:], s, amtPaid, expiry)
+		log.Debugf("Invoice(%x): %v, amt=%v, expiry=%v, circuit=%v",
+			rHash[:], s, amtPaid, expiry, circuitKey)
 	}
 
 	// If this isn't a debug invoice, then we'll attempt to settle an

invoices/invoiceregistry_test.go

@@ -64,6 +64,15 @@ func newTestContext(t *testing.T) (*InvoiceRegistry, func()) {
 	}
 }
 
+func getCircuitKey(htlcID uint64) channeldb.CircuitKey {
+	return channeldb.CircuitKey{
+		ChanID: lnwire.ShortChannelID{
+			BlockHeight: 1, TxIndex: 2, TxPosition: 3,
+		},
+		HtlcID: htlcID,
+	}
+}
+
 // TestSettleInvoice tests settling of an invoice and related notifications.
 func TestSettleInvoice(t *testing.T) {
 	registry, cleanup := newTestContext(t)
@@ -121,7 +130,8 @@ func TestSettleInvoice(t *testing.T) {
 	// Settle invoice with a slightly higher amount.
 	amtPaid := lnwire.MilliSatoshi(100500)
 	_, err = registry.NotifyExitHopHtlc(
-		hash, amtPaid, testHtlcExpiry, testCurrentHeight, hodlChan, nil,
+		hash, amtPaid, testHtlcExpiry, testCurrentHeight,
+		getCircuitKey(0), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatal(err)
@@ -153,10 +163,11 @@ func TestSettleInvoice(t *testing.T) {
 		t.Fatal("no update received")
 	}
 
-	// Try to settle again. We need this idempotent behaviour after a
-	// restart.
+	// Try to settle again with the same htlc id. We need this idempotent
+	// behaviour after a restart.
 	event, err := registry.NotifyExitHopHtlc(
-		hash, amtPaid, testHtlcExpiry, testCurrentHeight, hodlChan, nil,
+		hash, amtPaid, testHtlcExpiry, testCurrentHeight,
+		getCircuitKey(0), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatalf("unexpected NotifyExitHopHtlc error: %v", err)
@@ -165,12 +176,12 @@ func TestSettleInvoice(t *testing.T) {
 		t.Fatal("expected settle event")
 	}
 
-	// Try to settle again with a higher amount. This payment should also be
-	// accepted, to prevent any change in behaviour for a paid invoice that
-	// may open up a probe vector.
+	// Try to settle again with a new higher-valued htlc. This payment
+	// should also be accepted, to prevent any change in behaviour for a
+	// paid invoice that may open up a probe vector.
 	event, err = registry.NotifyExitHopHtlc(
 		hash, amtPaid+600, testHtlcExpiry, testCurrentHeight,
-		hodlChan, nil,
+		getCircuitKey(1), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatalf("unexpected NotifyExitHopHtlc error: %v", err)
@@ -183,7 +194,7 @@ func TestSettleInvoice(t *testing.T) {
 	// would have failed if it were the first payment.
 	event, err = registry.NotifyExitHopHtlc(
 		hash, amtPaid-600, testHtlcExpiry, testCurrentHeight,
-		hodlChan, nil,
+		getCircuitKey(2), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatalf("unexpected NotifyExitHopHtlc error: %v", err)
@@ -306,7 +317,8 @@ func TestCancelInvoice(t *testing.T) {
 	// succeed.
 	hodlChan := make(chan interface{})
 	event, err := registry.NotifyExitHopHtlc(
-		hash, amt, testHtlcExpiry, testCurrentHeight, hodlChan, nil,
+		hash, amt, testHtlcExpiry, testCurrentHeight,
+		getCircuitKey(0), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatal("expected settlement of a canceled invoice to succeed")
@@ -382,7 +394,8 @@ func TestHoldInvoice(t *testing.T) {
 	// NotifyExitHopHtlc without a preimage present in the invoice registry
 	// should be possible.
 	event, err := registry.NotifyExitHopHtlc(
-		hash, amtPaid, testHtlcExpiry, testCurrentHeight, hodlChan, nil,
+		hash, amtPaid, testHtlcExpiry, testCurrentHeight,
+		getCircuitKey(0), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatalf("expected settle to succeed but got %v", err)
@@ -393,7 +406,8 @@ func TestHoldInvoice(t *testing.T) {
 
 	// Test idempotency.
 	event, err = registry.NotifyExitHopHtlc(
-		hash, amtPaid, testHtlcExpiry, testCurrentHeight, hodlChan, nil,
+		hash, amtPaid, testHtlcExpiry, testCurrentHeight,
+		getCircuitKey(0), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatalf("expected settle to succeed but got %v", err)
@@ -406,7 +420,7 @@ func TestHoldInvoice(t *testing.T) {
 	// is a replay.
 	event, err = registry.NotifyExitHopHtlc(
 		hash, amtPaid, testHtlcExpiry, testCurrentHeight+10,
-		getCircuitKey(0), hodlChan,
+		getCircuitKey(0), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatalf("expected settle to succeed but got %v", err)
@@ -420,7 +434,7 @@ func TestHoldInvoice(t *testing.T) {
 	// doesn't track individual htlcs it is accepted.
 	event, err = registry.NotifyExitHopHtlc(
 		hash, amtPaid, 1, testCurrentHeight,
-		getCircuitKey(1), hodlChan,
+		getCircuitKey(1), hodlChan, nil,
 	)
 	if err != nil {
 		t.Fatalf("expected settle to succeed but got %v", err)
@@ -520,7 +534,8 @@ func TestUnknownInvoice(t *testing.T) {
 	hodlChan := make(chan interface{})
 	amt := lnwire.MilliSatoshi(100000)
 	_, err := registry.NotifyExitHopHtlc(
-		hash, amt, testHtlcExpiry, testCurrentHeight, hodlChan, nil,
+		hash, amt, testHtlcExpiry, testCurrentHeight,
+		getCircuitKey(0), hodlChan, nil,
 	)
 	if err != channeldb.ErrInvoiceNotFound {
 		t.Fatal("expected invoice not found error")