invoices+htlcswitch+lnrpc: cancel invoice

channeldb/invoices.go

@@ -62,6 +62,10 @@ var (
 	// ErrInvoiceAlreadySettled is returned when the invoice is already
 	// settled.
 	ErrInvoiceAlreadySettled = errors.New("invoice already settled")
+
+	// ErrInvoiceAlreadyCanceled is returned when the invoice is already
+	// canceled.
+	ErrInvoiceAlreadyCanceled = errors.New("invoice already canceled")
 )
 
 const (
@@ -90,6 +94,9 @@ const (
 	// ContractSettled means the htlc is settled and the invoice has been
 	// paid.
 	ContractSettled ContractState = 1
+
+	// ContractCanceled means the invoice has been canceled.
+	ContractCanceled ContractState = 2
 )
 
 // String returns a human readable identifier for the ContractState type.
@@ -99,6 +106,8 @@ func (c ContractState) String() string {
 		return "Open"
 	case ContractSettled:
 		return "Settled"
+	case ContractCanceled:
+		return "Canceled"
 	}
 
 	return "Unknown"
@@ -641,6 +650,37 @@ func (d *DB) SettleInvoice(paymentHash [32]byte,
 	return settledInvoice, err
 }
 
+// CancelInvoice attempts to cancel the invoice corresponding to the passed
+// payment hash.
+func (d *DB) CancelInvoice(paymentHash lntypes.Hash) (*Invoice, error) {
+	var canceledInvoice *Invoice
+	err := d.Update(func(tx *bbolt.Tx) error {
+		invoices, err := tx.CreateBucketIfNotExists(invoiceBucket)
+		if err != nil {
+			return err
+		}
+		invoiceIndex, err := invoices.CreateBucketIfNotExists(
+			invoiceIndexBucket,
+		)
+		if err != nil {
+			return err
+		}
+
+		// Check the invoice index to see if an invoice paying to this
+		// hash exists within the DB.
+		invoiceNum := invoiceIndex.Get(paymentHash[:])
+		if invoiceNum == nil {
+			return ErrInvoiceNotFound
+		}
+
+		canceledInvoice, err = cancelInvoice(invoices, invoiceNum)
+
+		return err
+	})
+
+	return canceledInvoice, err
+}
+
 // InvoicesSettledSince can be used by callers to catch up any settled invoices
 // they missed within the settled invoice time series. We'll return all known
 // settled invoice that have a settle index higher than the passed
@@ -896,8 +936,11 @@ func settleInvoice(invoices, settleIndex *bbolt.Bucket, invoiceNum []byte,
 		return nil, err
 	}
 
-	if invoice.Terms.State == ContractSettled {
+	switch invoice.Terms.State {
+	case ContractSettled:
 		return &invoice, ErrInvoiceAlreadySettled
+	case ContractCanceled:
+		return &invoice, ErrInvoiceAlreadyCanceled
 	}
 
 	// Now that we know the invoice hasn't already been settled, we'll
@@ -930,3 +973,32 @@ func settleInvoice(invoices, settleIndex *bbolt.Bucket, invoiceNum []byte,
 
 	return &invoice, nil
 }
+
+func cancelInvoice(invoices *bbolt.Bucket, invoiceNum []byte) (
+	*Invoice, error) {
+
+	invoice, err := fetchInvoice(invoiceNum, invoices)
+	if err != nil {
+		return nil, err
+	}
+
+	switch invoice.Terms.State {
+	case ContractSettled:
+		return &invoice, ErrInvoiceAlreadySettled
+	case ContractCanceled:
+		return &invoice, ErrInvoiceAlreadyCanceled
+	}
+
+	invoice.Terms.State = ContractCanceled
+
+	var buf bytes.Buffer
+	if err := serializeInvoice(&buf, &invoice); err != nil {
+		return nil, err
+	}
+
+	if err := invoices.Put(invoiceNum[:], buf.Bytes()); err != nil {
+		return nil, err
+	}
+
+	return &invoice, nil
+}

htlcswitch/interfaces.go

@@ -20,6 +20,10 @@ type InvoiceDatabase interface {
 	// SettleInvoice attempts to mark an invoice corresponding to the
 	// passed payment hash as fully settled.
 	SettleInvoice(payHash lntypes.Hash, paidAmount lnwire.MilliSatoshi) error
+
+	// CancelInvoice attempts to cancel the invoice corresponding to the
+	// passed payment hash.
+	CancelInvoice(payHash lntypes.Hash) error
 }
 
 // ChannelLink is an interface which represents the subsystem for managing the

htlcswitch/link.go

@@ -2337,6 +2337,23 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 				continue
 			}
 
+			// Reject htlcs for canceled invoices.
+			if invoice.Terms.State == channeldb.ContractCanceled {
+				l.errorf("Rejecting htlc due to canceled " +
+					"invoice")
+
+				failure := lnwire.NewFailUnknownPaymentHash(
+					pd.Amount,
+				)
+				l.sendHTLCError(
+					pd.HtlcIndex, failure, obfuscator,
+					pd.SourceRef,
+				)
+
+				needUpdate = true
+				continue
+			}
+
 			// If the invoice is already settled, we choose to
 			// accept the payment to simplify failure recovery.
 			//

htlcswitch/mock.go

@@ -18,7 +18,7 @@ import (
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/go-errors/errors"
-	"github.com/lightningnetwork/lightning-onion"
+	sphinx "github.com/lightningnetwork/lightning-onion"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/contractcourt"
@@ -735,6 +735,25 @@ func (i *mockInvoiceRegistry) SettleInvoice(rhash lntypes.Hash,
 	return nil
 }
 
+func (i *mockInvoiceRegistry) CancelInvoice(payHash lntypes.Hash) error {
+	i.Lock()
+	defer i.Unlock()
+
+	invoice, ok := i.invoices[payHash]
+	if !ok {
+		return channeldb.ErrInvoiceNotFound
+	}
+
+	if invoice.Terms.State == channeldb.ContractCanceled {
+		return nil
+	}
+
+	invoice.Terms.State = channeldb.ContractCanceled
+	i.invoices[payHash] = invoice
+
+	return nil
+}
+
 func (i *mockInvoiceRegistry) AddInvoice(invoice channeldb.Invoice) error {
 	i.Lock()
 	defer i.Unlock()

invoices/invoiceregistry.go

@@ -162,7 +162,11 @@ func (i *InvoiceRegistry) invoiceEventNotifier() {
 		// A sub-systems has just modified the invoice state, so we'll
 		// dispatch notifications to all registered clients.
 		case event := <-i.invoiceEvents:
+			// For backwards compatibility, do not notify all
+			// invoice subscribers of cancel events
+			if event.state != channeldb.ContractCanceled {
 				i.dispatchToClients(event)
+			}
 			i.dispatchToSingleClients(event)
 
 		case <-i.quit:
@@ -256,7 +260,7 @@ func (i *InvoiceRegistry) dispatchToClients(event *invoiceEvent) {
 		case channeldb.ContractOpen:
 			client.addIndex = invoice.AddIndex
 		default:
-			log.Errorf("unknown invoice state: %v", event.state)
+			log.Errorf("unexpected invoice state: %v", event.state)
 		}
 	}
 }
@@ -476,6 +480,34 @@ func (i *InvoiceRegistry) SettleInvoice(rHash lntypes.Hash,
 	return nil
 }
 
+// CancelInvoice attempts to cancel the invoice corresponding to the passed
+// payment hash.
+func (i *InvoiceRegistry) CancelInvoice(payHash lntypes.Hash) error {
+	i.Lock()
+	defer i.Unlock()
+
+	log.Debugf("Canceling invoice %v", payHash)
+
+	invoice, err := i.cdb.CancelInvoice(payHash)
+
+	// Implement idempotency by returning success if the invoice was already
+	// canceled.
+	if err == channeldb.ErrInvoiceAlreadyCanceled {
+		log.Debugf("Invoice %v already canceled", payHash)
+		return nil
+	}
+
+	if err != nil {
+		return err
+	}
+
+	log.Infof("Invoice %v canceled", payHash)
+
+	i.notifyClients(payHash, invoice, channeldb.ContractCanceled)
+
+	return nil
+}
+
 // notifyClients notifies all currently registered invoice notification clients
 // of a newly added/settled invoice.
 func (i *InvoiceRegistry) notifyClients(hash lntypes.Hash,

invoices/invoiceregistry_test.go

@@ -150,6 +150,122 @@ func TestSettleInvoice(t *testing.T) {
 	if inv.AmtPaid != amtPaid {
 		t.Fatal("expected amount to be unchanged")
 	}
+
+	// Try to cancel.
+	err = registry.CancelInvoice(hash)
+	if err != channeldb.ErrInvoiceAlreadySettled {
+		t.Fatal("expected cancelation of a settled invoice to fail")
+	}
+}
+
+// TestCancelInvoice tests cancelation of an invoice and related notifications.
+func TestCancelInvoice(t *testing.T) {
+	cdb, cleanup, err := newDB()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cleanup()
+
+	// Instantiate and start the invoice registry.
+	registry := NewRegistry(cdb, &chaincfg.MainNetParams)
+
+	err = registry.Start()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer registry.Stop()
+
+	allSubscriptions := registry.SubscribeNotifications(0, 0)
+	defer allSubscriptions.Cancel()
+
+	// Try to cancel the not yet existing invoice. This should fail.
+	err = registry.CancelInvoice(hash)
+	if err != channeldb.ErrInvoiceNotFound {
+		t.Fatalf("expected ErrInvoiceNotFound, but got %v", err)
+	}
+
+	// Subscribe to the not yet existing invoice.
+	subscription := registry.SubscribeSingleInvoice(hash)
+	defer subscription.Cancel()
+
+	if subscription.hash != hash {
+		t.Fatalf("expected subscription for provided hash")
+	}
+
+	// Add the invoice.
+	amt := lnwire.MilliSatoshi(100000)
+	invoice := &channeldb.Invoice{
+		Terms: channeldb.ContractTerm{
+			PaymentPreimage: preimage,
+			Value:           amt,
+		},
+	}
+
+	_, err = registry.AddInvoice(invoice, hash)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// We expect the open state to be sent to the single invoice subscriber.
+	select {
+	case update := <-subscription.Updates:
+		if update.Terms.State != channeldb.ContractOpen {
+			t.Fatalf(
+				"expected state ContractOpen, but got %v",
+				update.Terms.State,
+			)
+		}
+	case <-time.After(testTimeout):
+		t.Fatal("no update received")
+	}
+
+	// We expect a new invoice notification to be sent out.
+	select {
+	case newInvoice := <-allSubscriptions.NewInvoices:
+		if newInvoice.Terms.State != channeldb.ContractOpen {
+			t.Fatalf(
+				"expected state ContractOpen, but got %v",
+				newInvoice.Terms.State,
+			)
+		}
+	case <-time.After(testTimeout):
+		t.Fatal("no update received")
+	}
+
+	// Cancel invoice.
+	err = registry.CancelInvoice(hash)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// We expect the canceled state to be sent to the single invoice
+	// subscriber.
+	select {
+	case update := <-subscription.Updates:
+		if update.Terms.State != channeldb.ContractCanceled {
+			t.Fatalf(
+				"expected state ContractCanceled, but got %v",
+				update.Terms.State,
+			)
+		}
+	case <-time.After(testTimeout):
+		t.Fatal("no update received")
+	}
+
+	// We expect no cancel notification to be sent to all invoice
+	// subscribers (backwards compatibility).
+
+	// Try to cancel again.
+	err = registry.CancelInvoice(hash)
+	if err != nil {
+		t.Fatal("expected cancelation of a canceled invoice to succeed")
+	}
+
+	// Try to settle. This should not be possible.
+	err = registry.SettleInvoice(hash, amt)
+	if err != channeldb.ErrInvoiceAlreadyCanceled {
+		t.Fatal("expected settlement of a canceled invoice to fail")
+	}
 }
 
 func newDB() (*channeldb.DB, func(), error) {

lnrpc/invoicesrpc/invoices.pb.go

@@ -25,6 +25,80 @@ var _ = math.Inf
 // proto package needs to be updated.
 const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
 
+type CancelInvoiceMsg struct {
+	// / Hash corresponding to the invoice to cancel.
+	PaymentHash          []byte   `protobuf:"bytes,1,opt,name=payment_hash,json=paymentHash,proto3" json:"payment_hash,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *CancelInvoiceMsg) Reset()         { *m = CancelInvoiceMsg{} }
+func (m *CancelInvoiceMsg) String() string { return proto.CompactTextString(m) }
+func (*CancelInvoiceMsg) ProtoMessage()    {}
+func (*CancelInvoiceMsg) Descriptor() ([]byte, []int) {
+	return fileDescriptor_invoices_1b708c9c030aea0e, []int{0}
+}
+func (m *CancelInvoiceMsg) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_CancelInvoiceMsg.Unmarshal(m, b)
+}
+func (m *CancelInvoiceMsg) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_CancelInvoiceMsg.Marshal(b, m, deterministic)
+}
+func (dst *CancelInvoiceMsg) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_CancelInvoiceMsg.Merge(dst, src)
+}
+func (m *CancelInvoiceMsg) XXX_Size() int {
+	return xxx_messageInfo_CancelInvoiceMsg.Size(m)
+}
+func (m *CancelInvoiceMsg) XXX_DiscardUnknown() {
+	xxx_messageInfo_CancelInvoiceMsg.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_CancelInvoiceMsg proto.InternalMessageInfo
+
+func (m *CancelInvoiceMsg) GetPaymentHash() []byte {
+	if m != nil {
+		return m.PaymentHash
+	}
+	return nil
+}
+
+type CancelInvoiceResp struct {
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *CancelInvoiceResp) Reset()         { *m = CancelInvoiceResp{} }
+func (m *CancelInvoiceResp) String() string { return proto.CompactTextString(m) }
+func (*CancelInvoiceResp) ProtoMessage()    {}
+func (*CancelInvoiceResp) Descriptor() ([]byte, []int) {
+	return fileDescriptor_invoices_1b708c9c030aea0e, []int{1}
+}
+func (m *CancelInvoiceResp) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_CancelInvoiceResp.Unmarshal(m, b)
+}
+func (m *CancelInvoiceResp) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_CancelInvoiceResp.Marshal(b, m, deterministic)
+}
+func (dst *CancelInvoiceResp) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_CancelInvoiceResp.Merge(dst, src)
+}
+func (m *CancelInvoiceResp) XXX_Size() int {
+	return xxx_messageInfo_CancelInvoiceResp.Size(m)
+}
+func (m *CancelInvoiceResp) XXX_DiscardUnknown() {
+	xxx_messageInfo_CancelInvoiceResp.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_CancelInvoiceResp proto.InternalMessageInfo
+
+func init() {
+	proto.RegisterType((*CancelInvoiceMsg)(nil), "invoicesrpc.CancelInvoiceMsg")
+	proto.RegisterType((*CancelInvoiceResp)(nil), "invoicesrpc.CancelInvoiceResp")
+}
+
 // Reference imports to suppress errors if they are not otherwise used.
 var _ context.Context
 var _ grpc.ClientConn
@@ -42,6 +116,11 @@ type InvoicesClient interface {
 	// to notify the client of state transitions of the specified invoice.
 	// Initially the current invoice state is always sent out.
 	SubscribeSingleInvoice(ctx context.Context, in *lnrpc.PaymentHash, opts ...grpc.CallOption) (Invoices_SubscribeSingleInvoiceClient, error)
+	// *
+	// CancelInvoice cancels a currently open invoice. If the invoice is already
+	// canceled, this call will succeed. If the invoice is already settled, it will
+	// fail.
+	CancelInvoice(ctx context.Context, in *CancelInvoiceMsg, opts ...grpc.CallOption) (*CancelInvoiceResp, error)
 }
 
 type invoicesClient struct {
@@ -84,6 +163,15 @@ func (x *invoicesSubscribeSingleInvoiceClient) Recv() (*lnrpc.Invoice, error) {
 	return m, nil
 }
 
+func (c *invoicesClient) CancelInvoice(ctx context.Context, in *CancelInvoiceMsg, opts ...grpc.CallOption) (*CancelInvoiceResp, error) {
+	out := new(CancelInvoiceResp)
+	err := c.cc.Invoke(ctx, "/invoicesrpc.Invoices/CancelInvoice", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 // InvoicesServer is the server API for Invoices service.
 type InvoicesServer interface {
 	// *
@@ -91,6 +179,11 @@ type InvoicesServer interface {
 	// to notify the client of state transitions of the specified invoice.
 	// Initially the current invoice state is always sent out.
 	SubscribeSingleInvoice(*lnrpc.PaymentHash, Invoices_SubscribeSingleInvoiceServer) error
+	// *
+	// CancelInvoice cancels a currently open invoice. If the invoice is already
+	// canceled, this call will succeed. If the invoice is already settled, it will
+	// fail.
+	CancelInvoice(context.Context, *CancelInvoiceMsg) (*CancelInvoiceResp, error)
 }
 
 func RegisterInvoicesServer(s *grpc.Server, srv InvoicesServer) {
@@ -118,10 +211,33 @@ func (x *invoicesSubscribeSingleInvoiceServer) Send(m *lnrpc.Invoice) error {
 	return x.ServerStream.SendMsg(m)
 }
 
+func _Invoices_CancelInvoice_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(CancelInvoiceMsg)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(InvoicesServer).CancelInvoice(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/invoicesrpc.Invoices/CancelInvoice",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(InvoicesServer).CancelInvoice(ctx, req.(*CancelInvoiceMsg))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 var _Invoices_serviceDesc = grpc.ServiceDesc{
 	ServiceName: "invoicesrpc.Invoices",
 	HandlerType: (*InvoicesServer)(nil),
-	Methods:     []grpc.MethodDesc{},
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "CancelInvoice",
+			Handler:    _Invoices_CancelInvoice_Handler,
+		},
+	},
 	Streams: []grpc.StreamDesc{
 		{
 			StreamName:    "SubscribeSingleInvoice",
@@ -133,21 +249,25 @@ var _Invoices_serviceDesc = grpc.ServiceDesc{
 }
 
 func init() {
-	proto.RegisterFile("invoicesrpc/invoices.proto", fileDescriptor_invoices_c6414974947f2940)
+	proto.RegisterFile("invoicesrpc/invoices.proto", fileDescriptor_invoices_1b708c9c030aea0e)
 }
 
-var fileDescriptor_invoices_c6414974947f2940 = []byte{
+var fileDescriptor_invoices_1b708c9c030aea0e = []byte{
-	// 177 bytes of a gzipped FileDescriptorProto
+	// 246 bytes of a gzipped FileDescriptorProto
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-	0x00,
+	0xee, 0xaa, 0xe7, 0xa2, 0xe1, 0x4f, 0x6c, 0xbb, 0x77, 0x03, 0x3f, 0x96, 0x9d, 0x07, 0xca, 0xff,
+	0xd0, 0xe2, 0x64, 0xbd, 0xbc, 0x80, 0xbb, 0x1d, 0xbf, 0x5c, 0x3a, 0x28, 0x7e, 0xde, 0x4a, 0x43,
+	0x33, 0x15, 0xc0, 0xf9, 0x82, 0x80, 0x0e, 0x6d, 0xf9, 0xa4, 0xf4, 0xae, 0x02, 0xbe, 0xa9, 0x25,
+	0x82, 0xea, 0xd4, 0xb4, 0x1b, 0xcb, 0x4f, 0x1a, 0xff, 0x04, 0x00, 0x00, 0xff, 0xff, 0xd2, 0xc3,
+	0x7e, 0x3a, 0x78, 0x01, 0x00, 0x00,
 }

lnrpc/invoicesrpc/invoices.proto

@@ -16,5 +16,17 @@ service Invoices {
     Initially the current invoice state is always sent out.
     */
     rpc SubscribeSingleInvoice (lnrpc.PaymentHash) returns (stream lnrpc.Invoice);
+
+    /**
+    CancelInvoice cancels a currently open invoice. If the invoice is already 
+    canceled, this call will succeed. If the invoice is already settled, it will
+    fail.
+    */
+    rpc CancelInvoice(CancelInvoiceMsg) returns (CancelInvoiceResp);
 }
 
+message CancelInvoiceMsg {
+    /// Hash corresponding to the invoice to cancel.
+    bytes payment_hash = 1;
+} 
+message CancelInvoiceResp {}

lnrpc/invoicesrpc/invoices_server.go

@@ -8,10 +8,11 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/lightningnetwork/lnd/lnrpc"
-	"github.com/lightningnetwork/lnd/lntypes"
 	"google.golang.org/grpc"
 	"gopkg.in/macaroon-bakery.v2/bakery"
+
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lntypes"
 )
 
 const (
@@ -26,6 +27,10 @@ var (
 	// macaroonOps are the set of capabilities that our minted macaroon (if
 	// it doesn't already exist) will have.
 	macaroonOps = []bakery.Op{
+		{
+			Entity: "invoices",
+			Action: "write",
+		},
 		{
 			Entity: "invoices",
 			Action: "read",
@@ -38,6 +43,10 @@ var (
 			Entity: "invoices",
 			Action: "read",
 		}},
+		"/invoicesrpc.Invoices/CancelInvoice": {{
+			Entity: "invoices",
+			Action: "write",
+		}},
 	}
 
 	// DefaultInvoicesMacFilename is the default name of the invoices
@@ -181,3 +190,24 @@ func (s *Server) SubscribeSingleInvoice(req *lnrpc.PaymentHash,
 		}
 	}
 }
+
+// CancelInvoice cancels a currently open invoice. If the invoice is already
+// canceled, this call will succeed. If the invoice is already settled, it will
+// fail.
+func (s *Server) CancelInvoice(ctx context.Context,
+	in *CancelInvoiceMsg) (*CancelInvoiceResp, error) {
+
+	paymentHash, err := lntypes.NewHash(in.PaymentHash)
+	if err != nil {
+		return nil, err
+	}
+
+	err = s.cfg.InvoiceRegistry.CancelInvoice(*paymentHash)
+	if err != nil {
+		return nil, err
+	}
+
+	log.Infof("Canceled invoice %v", paymentHash)
+
+	return &CancelInvoiceResp{}, nil
+}

lnrpc/invoicesrpc/utils.go

@@ -59,8 +59,11 @@ func CreateRPCInvoice(invoice *channeldb.Invoice,
 		state = lnrpc.Invoice_OPEN
 	case channeldb.ContractSettled:
 		state = lnrpc.Invoice_SETTLED
+	case channeldb.ContractCanceled:
+		state = lnrpc.Invoice_CANCELED
 	default:
-		return nil, fmt.Errorf("unknown invoice state")
+		return nil, fmt.Errorf("unknown invoice state %v",
+			invoice.Terms.State)
 	}
 
 	return &lnrpc.Invoice{

lnrpc/rpc.proto

@@ -1850,6 +1850,7 @@ message Invoice {
     enum InvoiceState {
         OPEN = 0;
         SETTLED = 1;
+        CANCELED = 2;
     }
 
     /**

lnrpc/rpc.swagger.json

@@ -1141,7 +1141,8 @@
       "type": "string",
       "enum": [
         "OPEN",
-        "SETTLED"
+        "SETTLED",
+        "CANCELED"
       ],
       "default": "OPEN"
     },