instantout: check reservation expiry

Author: sputn1ck

instantout/actions.go

@@ -21,7 +21,7 @@ import (
 	"github.com/lightningnetwork/lnd/lntypes"
 )
 
-var (
+const (
 	// Define route independent max routing fees. We have currently no way
 	// to get a reliable estimate of the routing fees. Best we can do is
 	// the minimum routing fees, which is not very indicative.
@@ -46,6 +46,10 @@ var (
 	// defaultPollPaymentTime is the default time to poll the server for the
 	// payment status.
 	defaultPollPaymentTime = time.Second * 15
+
+	// htlcExpiryDelta is the delta in blocks we require between the htlc
+	// expiry and reservation expiry.
+	htlcExpiryDelta = int32(40)
 )
 
 // InitInstantOutCtx contains the context for the InitInstantOutAction.
@@ -96,6 +100,15 @@ func (f *FSM) InitInstantOutAction(eventCtx fsm.EventContext) fsm.EventType {
 		reservationAmt += uint64(res.Value)
 		reservationIds = append(reservationIds, resId[:])
 		reservations = append(reservations, res)
+
+		// Check that the reservation expiry is larger than the cltv
+		// expiry of the swap, with an additional delta to allow for
+		// preimage reveal.
+		if int32(res.Expiry) < initCtx.cltvExpiry+htlcExpiryDelta {
+			return f.HandleError(fmt.Errorf("reservation %x has "+
+				"expiry %v which is less than the swap expiry %v",
+				resId, res.Expiry, initCtx.cltvExpiry))
+		}
 	}
 
 	// Create the preimage for the swap.

instantout/manager.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/btcsuite/btcd/btcutil"
+	"github.com/lightninglabs/loop/fsm"
 	"github.com/lightninglabs/loop/instantout/reservation"
 	"github.com/lightninglabs/loop/swapserverrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
@@ -169,15 +170,10 @@ func (m *Manager) NewInstantOut(ctx context.Context,
 	// waiting for sweepless sweep to be confirmed.
 	err = instantOut.DefaultObserver.WaitForState(
 		ctx, defaultStateWaitTime, WaitForSweeplessSweepConfirmed,
+		fsm.WithAbortEarlyOnErrorOption(),
 	)
 	if err != nil {
-		if instantOut.LastActionError != nil {
-			return instantOut, fmt.Errorf(
-				"error waiting for sweepless sweep "+
-					"confirmed: %w", instantOut.LastActionError,
-			)
-		}
-		return instantOut, nil
+		return nil, err
 	}
 
 	return instantOut, nil