sweepbatcher: add change to PresignSweepsGroup

The batcher now presigns sweep groups including
an optional change output. Change is usually
leftover from the client's swap amount which
is returned to the client.

Author: hieblmi

sweepbatcher/sweep_batcher.go

@@ -125,6 +125,9 @@ type SweepInfo struct {
 	// value should be stable for a sweep. Currently presigned and
 	// non-presigned sweeps never appear in the same batch.
 	IsPresigned bool
+
+	// Change is an optional change output of the sweep.
+	Change *wire.TxOut
 }
 
 // SweepFetcher is used to get details of a sweep.
@@ -713,7 +716,8 @@ func (b *Batcher) Run(ctx context.Context) error {
 // swap. The order of sweeps is important. The first sweep serves as
 // primarySweepID if the group starts a new batch.
 func (b *Batcher) PresignSweepsGroup(ctx context.Context, inputs []Input,
-	sweepTimeout int32, destAddress btcutil.Address) error {
+	sweepTimeout int32, destAddress btcutil.Address,
+	changeOutput *wire.TxOut) error {
 
 	if len(inputs) == 0 {
 		return fmt.Errorf("no inputs passed to PresignSweepsGroup")
@@ -742,6 +746,7 @@ func (b *Batcher) PresignSweepsGroup(ctx context.Context, inputs []Input,
 			outpoint: input.Outpoint,
 			value:    input.Value,
 			timeout:  sweepTimeout,
+			change:   changeOutput,
 		}
 	}
 
@@ -1564,6 +1569,7 @@ func (b *Batcher) loadSweep(ctx context.Context, swapHash lntypes.Hash,
 		minFeeRate:             minFeeRate,
 		nonCoopHint:            s.NonCoopHint,
 		presigned:              s.IsPresigned,
+		change:                 s.Change,
 	}, nil
 }
 

sweepbatcher/sweep_batcher_presigned_test.go

@@ -113,7 +113,7 @@ func (h *mockPresignedHelper) DestPkScript(ctx context.Context,
 }
 
 // SignTx tries to sign the transaction. If all the inputs are online, it signs
-// the exact transaction passed and adds it to presignedBatches. Otherwise it
+// the exact transaction passed and adds it to presignedBatches. Otherwise, it
 // looks for a transaction in presignedBatches satisfying the criteria.
 func (h *mockPresignedHelper) SignTx(ctx context.Context,
 	primarySweepID wire.OutPoint, tx *wire.MsgTx, inputAmt btcutil.Amount,
@@ -273,7 +273,7 @@ func testPresigned_forgotten_presign(t *testing.T,
 	presignedHelper.SetOutpointOnline(op1, false)
 	err := batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op1, Value: 1_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.Error(t, err)
 	require.ErrorContains(t, err, "offline")
@@ -350,7 +350,7 @@ func testPresigned_input1_offline_then_input2(t *testing.T,
 	presignedHelper.SetOutpointOnline(op1, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op1, Value: 1_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 
@@ -413,7 +413,7 @@ func testPresigned_input1_offline_then_input2(t *testing.T,
 	presignedHelper.SetOutpointOnline(op2, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op2, Value: 2_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 
@@ -520,7 +520,7 @@ func testPresigned_min_relay_fee(t *testing.T,
 	presignedHelper.SetOutpointOnline(op1, true)
 	err := batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op1, Value: inputAmt}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 
@@ -644,7 +644,7 @@ func testPresigned_two_inputs_one_goes_offline(t *testing.T,
 	presignedHelper.SetOutpointOnline(op1, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op1, Value: 1_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 	require.NoError(t, batcher.AddSweep(ctx, &sweepReq1))
@@ -670,7 +670,7 @@ func testPresigned_two_inputs_one_goes_offline(t *testing.T,
 	presignedHelper.SetOutpointOnline(op2, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op2, Value: 2_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 	require.NoError(t, batcher.AddSweep(ctx, &sweepReq2))
@@ -780,7 +780,7 @@ func testPresigned_first_publish_fails(t *testing.T,
 	presignedHelper.SetOutpointOnline(op1, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op1, Value: 1_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 	presignedHelper.SetOutpointOnline(op1, false)
@@ -903,7 +903,7 @@ func testPresigned_locktime(t *testing.T,
 	presignedHelper.SetOutpointOnline(op1, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op1, Value: 1_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 	presignedHelper.SetOutpointOnline(op1, false)
@@ -994,14 +994,18 @@ func testPresigned_presigned_group(t *testing.T,
 	presignedHelper.SetOutpointOnline(op2, false)
 
 	// An attempt to presign must fail.
-	err = batcher.PresignSweepsGroup(ctx, group1, sweepTimeout, destAddr)
+	err = batcher.PresignSweepsGroup(
+		ctx, group1, sweepTimeout, destAddr, nil,
+	)
 	require.ErrorContains(t, err, "some outpoint is offline")
 
 	// Enable both outpoints.
 	presignedHelper.SetOutpointOnline(op2, true)
 
 	// An attempt to presign must succeed.
-	err = batcher.PresignSweepsGroup(ctx, group1, sweepTimeout, destAddr)
+	err = batcher.PresignSweepsGroup(
+		ctx, group1, sweepTimeout, destAddr, nil,
+	)
 	require.NoError(t, err)
 
 	// Add the sweep, triggering the publish attempt.
@@ -1053,7 +1057,9 @@ func testPresigned_presigned_group(t *testing.T,
 	presignedHelper.SetOutpointOnline(op4, true)
 
 	// An attempt to presign must succeed.
-	err = batcher.PresignSweepsGroup(ctx, group2, sweepTimeout, destAddr)
+	err = batcher.PresignSweepsGroup(
+		ctx, group2, sweepTimeout, destAddr, nil,
+	)
 	require.NoError(t, err)
 
 	// Add the sweep. It should go to the same batch.
@@ -1107,7 +1113,9 @@ func testPresigned_presigned_group(t *testing.T,
 	presignedHelper.SetOutpointOnline(op6, true)
 
 	// An attempt to presign must succeed.
-	err = batcher.PresignSweepsGroup(ctx, group3, sweepTimeout, destAddr)
+	err = batcher.PresignSweepsGroup(
+		ctx, group3, sweepTimeout, destAddr, nil,
+	)
 	require.NoError(t, err)
 
 	// Add the sweep. It should go to the same batch.
@@ -1215,9 +1223,9 @@ func testPresigned_presigned_and_regular_sweeps(t *testing.T, store testStore,
 
 	setFeeRate(feeRateLow)
 
-	/////////////////////////////////////
+	// ///////////////////////////////////
 	// Create the first regular sweep. //
-	/////////////////////////////////////
+	// ///////////////////////////////////
 	swapHash1 := lntypes.Hash{1, 1, 1}
 	op1 := wire.OutPoint{
 		Hash:  chainhash.Hash{1, 1},
@@ -1264,9 +1272,9 @@ func testPresigned_presigned_and_regular_sweeps(t *testing.T, store testStore,
 	require.Len(t, tx1.TxIn, 1)
 	require.Len(t, tx1.TxOut, 1)
 
-	///////////////////////////////////////
+	// /////////////////////////////////////
 	// Create the first presigned sweep. //
-	///////////////////////////////////////
+	// /////////////////////////////////////
 	swapHash2 := lntypes.Hash{2, 2, 2}
 	op2 := wire.OutPoint{
 		Hash:  chainhash.Hash{2, 2},
@@ -1304,7 +1312,7 @@ func testPresigned_presigned_and_regular_sweeps(t *testing.T, store testStore,
 	presignedHelper.SetOutpointOnline(op2, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op2, Value: 2_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 	require.NoError(t, batcher.AddSweep(ctx, &sweepReq2))
@@ -1319,9 +1327,9 @@ func testPresigned_presigned_and_regular_sweeps(t *testing.T, store testStore,
 	require.Len(t, tx2.TxOut, 1)
 	require.Equal(t, op2, tx2.TxIn[0].PreviousOutPoint)
 
-	//////////////////////////////////////
+	// ////////////////////////////////////
 	// Create the second regular sweep. //
-	//////////////////////////////////////
+	// ////////////////////////////////////
 	swapHash3 := lntypes.Hash{3, 3, 3}
 	op3 := wire.OutPoint{
 		Hash:  chainhash.Hash{3, 3},
@@ -1359,9 +1367,9 @@ func testPresigned_presigned_and_regular_sweeps(t *testing.T, store testStore,
 	// Deliver sweep request to batcher.
 	require.NoError(t, batcher.AddSweep(ctx, &sweepReq3))
 
-	////////////////////////////////////////
+	// //////////////////////////////////////
 	// Create the second presigned sweep. //
-	////////////////////////////////////////
+	// //////////////////////////////////////
 	swapHash4 := lntypes.Hash{4, 4, 4}
 	op4 := wire.OutPoint{
 		Hash:  chainhash.Hash{4, 4},
@@ -1399,7 +1407,7 @@ func testPresigned_presigned_and_regular_sweeps(t *testing.T, store testStore,
 	presignedHelper.SetOutpointOnline(op4, true)
 	err = batcher.PresignSweepsGroup(
 		ctx, []Input{{Outpoint: op4, Value: 3_000_000}},
-		sweepTimeout, destAddr,
+		sweepTimeout, destAddr, nil,
 	)
 	require.NoError(t, err)
 	require.NoError(t, batcher.AddSweep(ctx, &sweepReq4))
@@ -1520,7 +1528,7 @@ func testPresigned_purging(t *testing.T, numSwaps, numConfirmedSwaps int,
 
 		// An attempt to presign must succeed.
 		err := batcher.PresignSweepsGroup(
-			ctx, group, sweepTimeout, destAddr,
+			ctx, group, sweepTimeout, destAddr, nil,
 		)
 		require.NoError(t, err)
 
@@ -1584,11 +1592,11 @@ func testPresigned_purging(t *testing.T, numSwaps, numConfirmedSwaps int,
 
 		// An attempt to presign must succeed.
 		err := batcher.PresignSweepsGroup(
-			ctx, group, sweepTimeout, destAddr,
+			ctx, group, sweepTimeout, destAddr, nil,
 		)
 		require.NoError(t, err)
 
-		// Add the sweep, triggering the publish attempt.
+		// Add the sweep, triggering the publishing attempt.
 		require.NoError(t, batcher.AddSweep(ctx, &SweepRequest{
 			SwapHash: swapHash,
 			Inputs:   group,