multi: store loop out htlc confirmations on disk

To allow users to specify differing confirmation targets, we store the
swap conf target per-swap. This makes us restart safe, so we do not
forget confirmation values for swaps that are in flight when we restart.

Author: carlaKC

client_test.go

@@ -36,6 +36,8 @@ var (
 
 	swapInvoiceDesc   = "swap"
 	prepayInvoiceDesc = "prepay"
+
+	defaultConfirmations = int32(loopdb.DefaultLoopOutHtlcConfirmations)
 )
 
 // TestSuccess tests the loop out happy flow.
@@ -57,7 +59,7 @@ func TestSuccess(t *testing.T) {
 	signalPrepaymentResult := ctx.AssertPaid(prepayInvoiceDesc)
 
 	// Expect client to register for conf.
-	confIntent := ctx.AssertRegisterConf(false)
+	confIntent := ctx.AssertRegisterConf(false, defaultConfirmations)
 
 	testSuccess(ctx, testRequest.Amount, info.SwapHash,
 		signalPrepaymentResult, signalSwapPaymentResult, false,
@@ -83,7 +85,7 @@ func TestFailOffchain(t *testing.T) {
 	signalSwapPaymentResult := ctx.AssertPaid(swapInvoiceDesc)
 	signalPrepaymentResult := ctx.AssertPaid(prepayInvoiceDesc)
 
-	ctx.AssertRegisterConf(false)
+	ctx.AssertRegisterConf(false, defaultConfirmations)
 
 	signalSwapPaymentResult(
 		errors.New(lndclient.PaymentResultUnknownPaymentHash),
@@ -196,6 +198,7 @@ func testResume(t *testing.T, expired, preimageRevealed, expectSuccess bool) {
 			DestAddr:          dest,
 			SwapInvoice:       swapPayReq,
 			SweepConfTarget:   2,
+			HtlcConfirmations: loopdb.DefaultLoopOutHtlcConfirmations,
 			MaxSwapRoutingFee: 70000,
 			PrepayInvoice:     prePayReq,
 			SwapContract: loopdb.SwapContract{
@@ -232,7 +235,9 @@ func testResume(t *testing.T, expired, preimageRevealed, expectSuccess bool) {
 	signalPrepaymentResult := ctx.AssertPaid(prepayInvoiceDesc)
 
 	// Expect client to register for conf.
-	confIntent := ctx.AssertRegisterConf(preimageRevealed)
+	confIntent := ctx.AssertRegisterConf(
+		preimageRevealed, defaultConfirmations,
+	)
 
 	signalSwapPaymentResult(nil)
 	signalPrepaymentResult(nil)

loopdb/loopout.go

@@ -36,6 +36,10 @@ type LoopOutContract struct {
 	// client sweep tx.
 	SweepConfTarget int32
 
+	// HtlcConfirmations is the number of confirmations we require the on
+	// chain htlc to have before proceeding with the swap.
+	HtlcConfirmations uint32
+
 	// OutgoingChanSet is the set of short ids of channels that may be used.
 	// If empty, any channel may be used.
 	OutgoingChanSet ChannelSet

loopdb/store.go

@@ -77,11 +77,23 @@ var (
 	// value: concatenation of uint64 channel ids
 	outgoingChanSetKey = []byte("outgoing-chan-set")
 
+	// confirmationsKey is the key that stores the number of confirmations
+	// that were requested for a loop out swap.
+	//
+	// path: loopOutBucket -> swapBucket[hash] -> confirmationsKey
+	//
+	// value: uint32 confirmation value
+	confirmationsKey = []byte("confirmations")
+
 	byteOrder = binary.BigEndian
 
 	keyLength = 33
 )
 
+// DefaultLoopOutHtlcConfirmations is the default number of confirmations we
+// set for a loop out htlc.
+const DefaultLoopOutHtlcConfirmations uint32 = 1
+
 // fileExists returns true if the file exists, and false otherwise.
 func fileExists(path string) bool {
 	if _, err := os.Stat(path); err != nil {
@@ -242,6 +254,23 @@ func (s *boltSwapStore) FetchLoopOutSwaps() ([]*LoopOut, error) {
 				}
 			}
 
+			// Set our default number of confirmations for the swap.
+			contract.HtlcConfirmations = DefaultLoopOutHtlcConfirmations
+
+			// If we have the number of confirmations stored for
+			// this swap, we overwrite our default with the stored
+			// value.
+			confBytes := swapBucket.Get(confirmationsKey)
+			if confBytes != nil {
+				r := bytes.NewReader(confBytes)
+				err := binary.Read(
+					r, byteOrder, &contract.HtlcConfirmations,
+				)
+				if err != nil {
+					return err
+				}
+			}
+
 			updates, err := deserializeUpdates(swapBucket)
 			if err != nil {
 				return err
@@ -471,6 +500,18 @@ func (s *boltSwapStore) CreateLoopOut(hash lntypes.Hash,
 			return err
 		}
 
+		// Write our confirmation target under its own key.
+		var buf bytes.Buffer
+		err = binary.Write(&buf, byteOrder, swap.HtlcConfirmations)
+		if err != nil {
+			return err
+		}
+
+		err = swapBucket.Put(confirmationsKey, buf.Bytes())
+		if err != nil {
+			return err
+		}
+
 		// Finally, we'll create an empty updates bucket for this swap
 		// to track any future updates to the swap itself.
 		_, err = swapBucket.CreateBucket(updatesBucketKey)

loopdb/store_test.go

@@ -70,6 +70,7 @@ func TestLoopOutStore(t *testing.T) {
 		SwapInvoice:             "swapinvoice",
 		MaxSwapRoutingFee:       30,
 		SweepConfTarget:         2,
+		HtlcConfirmations:       2,
 		SwapPublicationDeadline: time.Unix(0, initiationTime.UnixNano()),
 	}
 

loopout.go

@@ -147,6 +147,7 @@ func newLoopOutSwap(globalCtx context.Context, cfg *swapConfig,
 		DestAddr:                request.DestAddr,
 		MaxSwapRoutingFee:       request.MaxSwapRoutingFee,
 		SweepConfTarget:         request.SweepConfTarget,
+		HtlcConfirmations:       loopdb.DefaultLoopOutHtlcConfirmations,
 		PrepayInvoice:           swapResp.prepayInvoice,
 		MaxPrepayRoutingFee:     request.MaxPrepayRoutingFee,
 		SwapPublicationDeadline: request.SwapPublicationDeadline,
@@ -606,8 +607,8 @@ func (s *loopOutSwap) waitForConfirmedHtlc(globalCtx context.Context) (
 	// Wait for confirmation of the on-chain htlc by watching for a tx
 	// producing the swap script output.
 	s.log.Infof(
-		"Register conf ntfn for swap script on chain (hh=%v)",
-		s.InitiationHeight,
+		"Register %v conf ntfn for swap script on chain (hh=%v)",
+		s.HtlcConfirmations, s.InitiationHeight,
 	)
 
 	// If we've revealed the preimage in a previous run, we expect to have
@@ -624,8 +625,8 @@ func (s *loopOutSwap) waitForConfirmedHtlc(globalCtx context.Context) (
 	defer cancel()
 	htlcConfChan, htlcErrChan, err :=
 		s.lnd.ChainNotifier.RegisterConfirmationsNtfn(
-			ctx, s.htlcTxHash, s.htlc.PkScript, 1,
-			s.InitiationHeight,
+			ctx, s.htlcTxHash, s.htlc.PkScript,
+			int32(s.HtlcConfirmations), s.InitiationHeight,
 		)
 	if err != nil {
 		return nil, err

loopout_test.go

@@ -116,7 +116,7 @@ func TestLoopOutPaymentParameters(t *testing.T) {
 
 	// Swap is expected to register for confirmation of the htlc. Assert
 	// this to prevent a blocked channel in the mock.
-	ctx.AssertRegisterConf(false)
+	ctx.AssertRegisterConf(false, defaultConfirmations)
 
 	// Cancel the swap. There is nothing else we need to assert. The payment
 	// parameters don't play a role in the remainder of the swap process.
@@ -191,7 +191,7 @@ func TestLateHtlcPublish(t *testing.T) {
 	signalPrepaymentResult := ctx.AssertPaid(prepayInvoiceDesc)
 
 	// Expect client to register for conf
-	ctx.AssertRegisterConf(false)
+	ctx.AssertRegisterConf(false, defaultConfirmations)
 
 	// // Wait too long before publishing htlc.
 	blockEpochChan <- int32(swap.CltvExpiry - 10)
@@ -290,7 +290,7 @@ func TestCustomSweepConfTarget(t *testing.T) {
 	signalPrepaymentResult(nil)
 
 	// Notify the confirmation notification for the HTLC.
-	ctx.AssertRegisterConf(false)
+	ctx.AssertRegisterConf(false, defaultConfirmations)
 
 	blockEpochChan <- ctx.Lnd.Height + 1
 
@@ -494,7 +494,7 @@ func TestPreimagePush(t *testing.T) {
 	signalPrepaymentResult(nil)
 
 	// Notify the confirmation notification for the HTLC.
-	ctx.AssertRegisterConf(false)
+	ctx.AssertRegisterConf(false, defaultConfirmations)
 
 	blockEpochChan <- ctx.Lnd.Height + 1
 

test/context.go

@@ -12,6 +12,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/zpay32"
+	"github.com/stretchr/testify/require"
 )
 
 // Context contains shared test context functions.
@@ -113,7 +114,7 @@ func (ctx *Context) AssertTrackPayment() TrackPaymentMessage {
 }
 
 // AssertRegisterConf asserts that a register for conf has been received.
-func (ctx *Context) AssertRegisterConf(expectTxHash bool) *ConfRegistration {
+func (ctx *Context) AssertRegisterConf(expectTxHash bool, confs int32) *ConfRegistration {
 	ctx.T.Helper()
 
 	// Expect client to register for conf
@@ -127,6 +128,11 @@ func (ctx *Context) AssertRegisterConf(expectTxHash bool) *ConfRegistration {
 		case !expectTxHash && confIntent.TxID != nil:
 			ctx.T.Fatalf("expected script only registration")
 		}
+
+		// Require that we registered for the number of confirmations
+		// the test expects.
+		require.Equal(ctx.T, confs, confIntent.NumConfs)
+
 	case <-time.After(Timeout):
 		ctx.T.Fatalf("htlc confirmed not subscribed to")
 	}