diff --git a/staticaddr/loopin/interface.go b/staticaddr/loopin/interface.go index f9b5f3ce..ec46b982 100644 --- a/staticaddr/loopin/interface.go +++ b/staticaddr/loopin/interface.go @@ -4,6 +4,7 @@ import ( "context" "github.com/btcsuite/btcd/btcutil" + "github.com/btcsuite/btcd/wire" "github.com/lightninglabs/loop" "github.com/lightninglabs/loop/fsm" "github.com/lightninglabs/loop/staticaddr/deposit" @@ -108,6 +109,16 @@ type QuoteGetter interface { numDeposits uint32, fast bool) (*loop.LoopInQuote, error) } +// TxOutChecker checks whether an outpoint is still available in the chain +// backend's UTXO view. +type TxOutChecker interface { + // GetTxOut returns nil if the outpoint is unavailable or spent. The + // includeMempool flag must be passed through to the underlying chain + // backend. + GetTxOut(ctx context.Context, outpoint wire.OutPoint, + includeMempool bool) (*wire.TxOut, error) +} + type NotificationManager interface { // SubscribeStaticLoopInSweepRequests subscribes to the static loop in // sweep requests. These are sent by the server to the client to request diff --git a/staticaddr/loopin/txout_checker.go b/staticaddr/loopin/txout_checker.go new file mode 100644 index 00000000..61463cc8 --- /dev/null +++ b/staticaddr/loopin/txout_checker.go @@ -0,0 +1,72 @@ +package loopin + +import ( + "context" + + "github.com/btcsuite/btcd/wire" + "github.com/lightninglabs/lndclient" +) + +// lndTxOutChecker checks outpoint availability using lnd's wallet transaction +// view. It returns nil for outputs already spent by a wallet-known transaction. +type lndTxOutChecker struct { + client lndclient.LightningClient +} + +// NewLndTxOutChecker creates a TxOutChecker backed by lnd. +func NewLndTxOutChecker(client lndclient.LightningClient) TxOutChecker { + return &lndTxOutChecker{ + client: client, + } +} + +// GetTxOut returns the tx output if lnd's transaction view still reports the +// outpoint as unspent. +func (c *lndTxOutChecker) GetTxOut(ctx context.Context, + outpoint wire.OutPoint, includeMempool bool) (*wire.TxOut, error) { + + endHeight := int32(0) + if includeMempool { + endHeight = -1 + } + + // We need lnd's wallet transaction view rather than only the funding + // transaction: a matching previous outpoint tells us the deposit has + // already been spent by a wallet-known transaction. When mempool spends + // matter, lnd exposes them through ListTransactions with endHeight=-1. + txs, err := c.client.ListTransactions(ctx, 0, endHeight) + if err != nil { + return nil, err + } + + outpointStr := outpoint.String() + for _, tx := range txs { + for _, prevOutpoint := range tx.PreviousOutpoints { + if prevOutpoint.GetOutpoint() == outpointStr { + return nil, nil + } + } + } + + for _, tx := range txs { + if tx.Tx == nil { + continue + } + + txHash := tx.TxHash + if txHash == "" { + txHash = tx.Tx.TxHash().String() + } + if txHash != outpoint.Hash.String() { + continue + } + + if int(outpoint.Index) >= len(tx.Tx.TxOut) { + return nil, nil + } + + return tx.Tx.TxOut[outpoint.Index], nil + } + + return nil, nil +} diff --git a/staticaddr/loopin/txout_checker_test.go b/staticaddr/loopin/txout_checker_test.go new file mode 100644 index 00000000..8e695e66 --- /dev/null +++ b/staticaddr/loopin/txout_checker_test.go @@ -0,0 +1,98 @@ +package loopin + +import ( + "context" + "errors" + "testing" + + "github.com/btcsuite/btcd/wire" + "github.com/lightninglabs/lndclient" + "github.com/lightningnetwork/lnd/lnrpc" + "github.com/stretchr/testify/require" +) + +func TestLndTxOutChecker(t *testing.T) { + fundingTx := wire.NewMsgTx(2) + fundingTx.AddTxOut(wire.NewTxOut(1000, []byte{0x01})) + fundingTx.AddTxOut(wire.NewTxOut(2000, []byte{0x02})) + + outpoint := wire.OutPoint{ + Hash: fundingTx.TxHash(), + Index: 1, + } + + t.Run("returns live tx output", func(t *testing.T) { + client := &mockTxListLightningClient{ + txs: []lndclient.Transaction{{ + Tx: fundingTx, + }}, + } + + checker := NewLndTxOutChecker(client) + txOut, err := checker.GetTxOut(t.Context(), outpoint, false) + require.NoError(t, err) + require.Equal(t, fundingTx.TxOut[outpoint.Index], txOut) + require.Equal(t, []txListCall{{ + startHeight: 0, + endHeight: 0, + }}, client.calls) + }) + + t.Run("returns nil for known spend", func(t *testing.T) { + client := &mockTxListLightningClient{ + txs: []lndclient.Transaction{{ + Tx: fundingTx, + }, { + PreviousOutpoints: []*lnrpc.PreviousOutPoint{{ + Outpoint: outpoint.String(), + }}, + }}, + } + + checker := NewLndTxOutChecker(client) + txOut, err := checker.GetTxOut(t.Context(), outpoint, true) + require.NoError(t, err) + require.Nil(t, txOut) + require.Equal(t, []txListCall{{ + startHeight: 0, + endHeight: -1, + }}, client.calls) + }) + + t.Run("returns error", func(t *testing.T) { + expectedErr := errors.New("list transactions failed") + client := &mockTxListLightningClient{ + err: expectedErr, + } + + checker := NewLndTxOutChecker(client) + txOut, err := checker.GetTxOut(t.Context(), outpoint, false) + require.ErrorIs(t, err, expectedErr) + require.Nil(t, txOut) + }) +} + +type txListCall struct { + startHeight int32 + endHeight int32 +} + +type mockTxListLightningClient struct { + lndclient.LightningClient + + txs []lndclient.Transaction + err error + calls []txListCall +} + +func (m *mockTxListLightningClient) ListTransactions(_ context.Context, + startHeight, endHeight int32, _ ...lndclient.ListTransactionsOption) ( + []lndclient.Transaction, error) { + + m.calls = append(m.calls, txListCall{ + startHeight: startHeight, + endHeight: endHeight, + }) + + return m.txs, m.err +}