invoices: cancel keysend invoices after 20 seconds

invoices/invoice_expiry_watcher.go

@@ -17,6 +17,7 @@ import (
 type invoiceExpiry struct {
 	PaymentHash lntypes.Hash
 	Expiry      time.Time
+	Keysend     bool
 }
 
 // Less implements PriorityQueueItem.Less such that the top item in the
@@ -41,7 +42,7 @@ type InvoiceExpiryWatcher struct {
 	clock clock.Clock
 
 	// cancelInvoice is a template method that cancels an expired invoice.
-	cancelInvoice func(lntypes.Hash) error
+	cancelInvoice func(lntypes.Hash, bool) error
 
 	// expiryQueue holds invoiceExpiry items and is used to find the next
 	// invoice to expire.
@@ -71,7 +72,7 @@ func NewInvoiceExpiryWatcher(clock clock.Clock) *InvoiceExpiryWatcher {
 // expects a cancellation function passed that will be use to cancel expired
 // invoices by their payment hash.
 func (ew *InvoiceExpiryWatcher) Start(
-	cancelInvoice func(lntypes.Hash) error) error {
+	cancelInvoice func(lntypes.Hash, bool) error) error {
 
 	ew.Lock()
 	defer ew.Unlock()
@@ -121,6 +122,7 @@ func (ew *InvoiceExpiryWatcher) prepareInvoice(
 	return &invoiceExpiry{
 		PaymentHash: paymentHash,
 		Expiry:      expiry,
+		Keysend:     len(invoice.PaymentRequest) == 0,
 	}
 }
 
@@ -190,7 +192,13 @@ func (ew *InvoiceExpiryWatcher) cancelNextExpiredInvoice() {
 			return
 		}
 
-		err := ew.cancelInvoice(top.PaymentHash)
+		// Don't force-cancel already accepted invoices. An exception to
+		// this are auto-generated keysend invoices. Because those start
+		// out in the Accepted state, the expiry field would never be
+		// used. Enabling cancellation for accepted keysend invoices
+		// creates a safety mechanism that can prevents channel
+		// force-closes.
+		err := ew.cancelInvoice(top.PaymentHash, top.Keysend)
 		if err != nil && err != channeldb.ErrInvoiceAlreadySettled &&
 			err != channeldb.ErrInvoiceAlreadyCanceled {
 

invoices/invoice_expiry_watcher_test.go

@@ -30,7 +30,9 @@ func newInvoiceExpiryWatcherTest(t *testing.T, now time.Time,
 		),
 	}
 
-	err := test.watcher.Start(func(paymentHash lntypes.Hash) error {
+	err := test.watcher.Start(func(paymentHash lntypes.Hash,
+		force bool) error {
+
 		test.canceledInvoices = append(test.canceledInvoices, paymentHash)
 		return nil
 	})
@@ -60,7 +62,7 @@ func (t *invoiceExpiryWatcherTest) checkExpectations() {
 // Tests that InvoiceExpiryWatcher can be started and stopped.
 func TestInvoiceExpiryWatcherStartStop(t *testing.T) {
 	watcher := NewInvoiceExpiryWatcher(clock.NewTestClock(testTime))
-	cancel := func(lntypes.Hash) error {
+	cancel := func(lntypes.Hash, bool) error {
 		t.Fatalf("unexpected call")
 		return nil
 	}

invoices/invoiceregistry.go

@@ -165,10 +165,7 @@ func (i *InvoiceRegistry) populateExpiryWatcher() error {
 func (i *InvoiceRegistry) Start() error {
 	// Start InvoiceExpiryWatcher and prepopulate it with existing active
 	// invoices.
-	err := i.expiryWatcher.Start(func(paymentHash lntypes.Hash) error {
-		cancelIfAccepted := false
-		return i.cancelInvoiceImpl(paymentHash, cancelIfAccepted)
-	})
+	err := i.expiryWatcher.Start(i.cancelInvoiceImpl)
 
 	if err != nil {
 		return err
@@ -694,7 +691,9 @@ func (i *InvoiceRegistry) processKeySend(ctx invoiceUpdateCtx) error {
 			Value:           amt,
 			PaymentPreimage: &preimage,
 			Features:        features,
+			Expiry:          20 * time.Second,
 		},
+		HodlInvoice: true,
 	}
 
 	// Insert invoice into database. Ignore duplicates, because this