htlcswitch: face race condition in unit tests by returning invoice

In this commit we modify the primary InvoiceRegistry interface within
the package to instead return a direct value for LookupInvoice rather
than a pointer. This fixes an existing race condition wherein a caller
could modify or read the value of the returned invoice.

htlcswitch/interfaces.go

@@ -12,7 +12,7 @@ import (
 type InvoiceDatabase interface {
 	// LookupInvoice attempts to look up an invoice according to it's 32
 	// byte payment hash.
-	LookupInvoice(chainhash.Hash) (*channeldb.Invoice, error)
+	LookupInvoice(chainhash.Hash) (channeldb.Invoice, error)
 
 	// SettleInvoice attempts to mark an invoice corresponding to the
 	// passed payment hash as fully settled.

htlcswitch/link_test.go

@@ -978,7 +978,7 @@ func TestChannelLinkMultiHopUnknownPaymentHash(t *testing.T) {
 	invoice.Terms.PaymentPreimage[0] ^= byte(255)
 
 	// Check who is last in the route and add invoice to server registry.
-	if err := n.carolServer.registry.AddInvoice(invoice); err != nil {
+	if err := n.carolServer.registry.AddInvoice(*invoice); err != nil {
 		t.Fatalf("unable to add invoice in carol registry: %v", err)
 	}
 
@@ -1955,7 +1955,7 @@ func TestChannelRetransmission(t *testing.T) {
 		// TODO(andrew.shvv) Will be removed if we move the notification center
 		// to the channel link itself.
 
-		var invoice *channeldb.Invoice
+		var invoice channeldb.Invoice
 		for i := 0; i < 20; i++ {
 			select {
 			case <-time.After(time.Millisecond * 200):

htlcswitch/mock.go

@@ -397,22 +397,22 @@ var _ ChannelLink = (*mockChannelLink)(nil)
 
 type mockInvoiceRegistry struct {
 	sync.Mutex
-	invoices map[chainhash.Hash]*channeldb.Invoice
+	invoices map[chainhash.Hash]channeldb.Invoice
 }
 
 func newMockRegistry() *mockInvoiceRegistry {
 	return &mockInvoiceRegistry{
-		invoices: make(map[chainhash.Hash]*channeldb.Invoice),
+		invoices: make(map[chainhash.Hash]channeldb.Invoice),
 	}
 }
 
-func (i *mockInvoiceRegistry) LookupInvoice(rHash chainhash.Hash) (*channeldb.Invoice, error) {
+func (i *mockInvoiceRegistry) LookupInvoice(rHash chainhash.Hash) (channeldb.Invoice, error) {
 	i.Lock()
 	defer i.Unlock()
 
 	invoice, ok := i.invoices[rHash]
 	if !ok {
-		return nil, errors.New("can't find mock invoice")
+		return channeldb.Invoice{}, errors.New("can't find mock invoice")
 	}
 
 	return invoice, nil
@@ -428,11 +428,12 @@ func (i *mockInvoiceRegistry) SettleInvoice(rhash chainhash.Hash) error {
 	}
 
 	invoice.Terms.Settled = true
+	i.invoices[rhash] = invoice
 
 	return nil
 }
 
-func (i *mockInvoiceRegistry) AddInvoice(invoice *channeldb.Invoice) error {
+func (i *mockInvoiceRegistry) AddInvoice(invoice channeldb.Invoice) error {
 	i.Lock()
 	defer i.Unlock()
 

htlcswitch/test_utils.go

@@ -549,7 +549,7 @@ func (n *threeHopNetwork) makePayment(sendingPeer, receivingPeer Peer,
 	rhash = fastsha256.Sum256(invoice.Terms.PaymentPreimage[:])
 
 	// Check who is last in the route and add invoice to server registry.
-	if err := receiver.registry.AddInvoice(invoice); err != nil {
+	if err := receiver.registry.AddInvoice(*invoice); err != nil {
 		paymentErr <- err
 		return &paymentResponse{
 			rhash: rhash,