11166428937

Committed 03 Oct 2024 05:07PM UTC coverage: 58.738% (-0.08%) from 58.817%

Build # 11166428937

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web-flow

Commit Message

Merge pull request #8960 from lightningnetwork/0-19-staging-rebased

[custom channels 5/5]: merge custom channel staging branch into master

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89.44

/contractcourt/htlc_success_resolver.go

package contractcourt

import (
        "encoding/binary"
        "io"
        "sync"

        "github.com/btcsuite/btcd/btcutil"
        "github.com/btcsuite/btcd/chaincfg/chainhash"
        "github.com/btcsuite/btcd/txscript"
        "github.com/btcsuite/btcd/wire"
        "github.com/davecgh/go-spew/spew"
        "github.com/lightningnetwork/lnd/chainntnfs"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/channeldb/models"
        "github.com/lightningnetwork/lnd/fn"
        "github.com/lightningnetwork/lnd/input"
        "github.com/lightningnetwork/lnd/labels"
        "github.com/lightningnetwork/lnd/lnutils"
        "github.com/lightningnetwork/lnd/lnwallet"
        "github.com/lightningnetwork/lnd/sweep"
)

// htlcSuccessResolver is a resolver that's capable of sweeping an incoming
// HTLC output on-chain. If this is the remote party's commitment, we'll sweep
// it directly from the commitment output *immediately*. If this is our
// commitment, we'll first broadcast the success transaction, then send it to
// the incubator for sweeping. That's it, no need to send any clean up
// messages.
//
// TODO(roasbeef): don't need to broadcast?
type htlcSuccessResolver struct {
        // htlcResolution is the incoming HTLC resolution for this HTLC. It
        // contains everything we need to properly resolve this HTLC.
        htlcResolution lnwallet.IncomingHtlcResolution

        // outputIncubating returns true if we've sent the output to the output
        // incubator (utxo nursery). In case the htlcResolution has non-nil
        // SignDetails, it means we will let the Sweeper handle broadcasting
        // the secondd-level transaction, and sweeping its output. In this case
        // we let this field indicate whether we need to broadcast the
        // second-level tx (false) or if it has confirmed and we must sweep the
        // second-level output (true).
        outputIncubating bool

        // resolved reflects if the contract has been fully resolved or not.
        resolved bool

        // broadcastHeight is the height that the original contract was
        // broadcast to the main-chain at. We'll use this value to bound any
        // historical queries to the chain for spends/confirmations.
        broadcastHeight uint32

        // htlc contains information on the htlc that we are resolving on-chain.
        htlc channeldb.HTLC

        // currentReport stores the current state of the resolver for reporting
        // over the rpc interface. This should only be reported in case we have
        // a non-nil SignDetails on the htlcResolution, otherwise the nursery
        // will produce reports.
        currentReport ContractReport

        // reportLock prevents concurrent access to the resolver report.
        reportLock sync.Mutex

        contractResolverKit

        htlcLeaseResolver
}

// newSuccessResolver instanties a new htlc success resolver.
func newSuccessResolver(res lnwallet.IncomingHtlcResolution,
        broadcastHeight uint32, htlc channeldb.HTLC,
        resCfg ResolverConfig) *htlcSuccessResolver {

        h := &htlcSuccessResolver{
                contractResolverKit: *newContractResolverKit(resCfg),
                htlcResolution:      res,
                broadcastHeight:     broadcastHeight,
                htlc:                htlc,
        }

        h.initReport()

        return h
}

// ResolverKey returns an identifier which should be globally unique for this
// particular resolver within the chain the original contract resides within.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcSuccessResolver) ResolverKey() []byte {
        // The primary key for this resolver will be the outpoint of the HTLC
        // on the commitment transaction itself. If this is our commitment,
        // then the output can be found within the signed success tx,
        // otherwise, it's just the ClaimOutpoint.
        var op wire.OutPoint
        if h.htlcResolution.SignedSuccessTx != nil {
                op = h.htlcResolution.SignedSuccessTx.TxIn[0].PreviousOutPoint
        } else {
                op = h.htlcResolution.ClaimOutpoint
        }

        key := newResolverID(op)
        return key[:]
}

// Resolve attempts to resolve an unresolved incoming HTLC that we know the
// preimage to. If the HTLC is on the commitment of the remote party, then we'll
// simply sweep it directly. Otherwise, we'll hand this off to the utxo nursery
// to do its duty. There is no need to make a call to the invoice registry
// anymore. Every HTLC has already passed through the incoming contest resolver
// and in there the invoice was already marked as settled.
//
// TODO(roasbeef): create multi to batch
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcSuccessResolver) Resolve(
        immediate bool) (ContractResolver, error) {

        // If we're already resolved, then we can exit early.
        if h.resolved {
                return nil, nil
        }

        // If the HTLC has custom records, then for now we'll pause resolution.
        //
        // TODO(roasbeef): Implement resolving HTLCs with custom records
        // (follow-up PR).
        if len(h.htlc.CustomRecords) != 0 {
                select { //nolint:gosimple
                case <-h.quit:
                        return nil, errResolverShuttingDown
                }
        }

        // If we don't have a success transaction, then this means that this is
        // an output on the remote party's commitment transaction.
        if h.htlcResolution.SignedSuccessTx == nil {
                return h.resolveRemoteCommitOutput(immediate)
        }

        // Otherwise this an output on our own commitment, and we must start by
        // broadcasting the second-level success transaction.
        secondLevelOutpoint, err := h.broadcastSuccessTx(immediate)
        if err != nil {
                return nil, err
        }

        // To wrap this up, we'll wait until the second-level transaction has
        // been spent, then fully resolve the contract.
        log.Infof("%T(%x): waiting for second-level HTLC output to be spent "+
                "after csv_delay=%v", h, h.htlc.RHash[:], h.htlcResolution.CsvDelay)

        spend, err := waitForSpend(
                secondLevelOutpoint,
                h.htlcResolution.SweepSignDesc.Output.PkScript,
                h.broadcastHeight, h.Notifier, h.quit,
        )
        if err != nil {
                return nil, err
        }

        h.reportLock.Lock()
        h.currentReport.RecoveredBalance = h.currentReport.LimboBalance
        h.currentReport.LimboBalance = 0
        h.reportLock.Unlock()

        h.resolved = true
        return nil, h.checkpointClaim(
                spend.SpenderTxHash, channeldb.ResolverOutcomeClaimed,
        )
}

// broadcastSuccessTx handles an HTLC output on our local commitment by
// broadcasting the second-level success transaction. It returns the ultimate
// outpoint of the second-level tx, that we must wait to be spent for the
// resolver to be fully resolved.
func (h *htlcSuccessResolver) broadcastSuccessTx(
        immediate bool) (*wire.OutPoint, error) {

        // If we have non-nil SignDetails, this means that have a 2nd level
        // HTLC transaction that is signed using sighash SINGLE|ANYONECANPAY
        // (the case for anchor type channels). In this case we can re-sign it
        // and attach fees at will. We let the sweeper handle this job.  We use
        // the checkpointed outputIncubating field to determine if we already
        // swept the HTLC output into the second level transaction.
        if h.htlcResolution.SignDetails != nil {
                return h.broadcastReSignedSuccessTx(immediate)
        }

        // Otherwise we'll publish the second-level transaction directly and
        // offer the resolution to the nursery to handle.
        log.Infof("%T(%x): broadcasting second-layer transition tx: %v",
                h, h.htlc.RHash[:], spew.Sdump(h.htlcResolution.SignedSuccessTx))

        // We'll now broadcast the second layer transaction so we can kick off
        // the claiming process.
        //
        // TODO(roasbeef): after changing sighashes send to tx bundler
        label := labels.MakeLabel(
                labels.LabelTypeChannelClose, &h.ShortChanID,
        )
        err := h.PublishTx(h.htlcResolution.SignedSuccessTx, label)
        if err != nil {
                return nil, err
        }

        // Otherwise, this is an output on our commitment transaction. In this
        // case, we'll send it to the incubator, but only if we haven't already
        // done so.
        if !h.outputIncubating {
                log.Infof("%T(%x): incubating incoming htlc output",
                        h, h.htlc.RHash[:])

                err := h.IncubateOutputs(
                        h.ChanPoint, fn.None[lnwallet.OutgoingHtlcResolution](),
                        fn.Some(h.htlcResolution),
                        h.broadcastHeight, fn.Some(int32(h.htlc.RefundTimeout)),
                )
                if err != nil {
                        return nil, err
                }

                h.outputIncubating = true

                if err := h.Checkpoint(h); err != nil {
                        log.Errorf("unable to Checkpoint: %v", err)
                        return nil, err
                }
        }

        return &h.htlcResolution.ClaimOutpoint, nil
}

// broadcastReSignedSuccessTx handles the case where we have non-nil
// SignDetails, and offers the second level transaction to the Sweeper, that
// will re-sign it and attach fees at will.
//
//nolint:funlen
func (h *htlcSuccessResolver) broadcastReSignedSuccessTx(immediate bool) (
        *wire.OutPoint, error) {

        // Keep track of the tx spending the HTLC output on the commitment, as
        // this will be the confirmed second-level tx we'll ultimately sweep.
        var commitSpend *chainntnfs.SpendDetail

        // We will have to let the sweeper re-sign the success tx and wait for
        // it to confirm, if we haven't already.
        isTaproot := txscript.IsPayToTaproot(
                h.htlcResolution.SweepSignDesc.Output.PkScript,
        )
        if !h.outputIncubating {
                var secondLevelInput input.HtlcSecondLevelAnchorInput
                if isTaproot {
                        //nolint:lll
                        secondLevelInput = input.MakeHtlcSecondLevelSuccessTaprootInput(
                                h.htlcResolution.SignedSuccessTx,
                                h.htlcResolution.SignDetails, h.htlcResolution.Preimage,
                                h.broadcastHeight,
                        )
                } else {
                        //nolint:lll
                        secondLevelInput = input.MakeHtlcSecondLevelSuccessAnchorInput(
                                h.htlcResolution.SignedSuccessTx,
                                h.htlcResolution.SignDetails, h.htlcResolution.Preimage,
                                h.broadcastHeight,
                        )
                }

                // Calculate the budget for this sweep.
                value := btcutil.Amount(
                        secondLevelInput.SignDesc().Output.Value,
                )
                budget := calculateBudget(
                        value, h.Budget.DeadlineHTLCRatio,
                        h.Budget.DeadlineHTLC,
                )

                // The deadline would be the CLTV in this HTLC output. If we
                // are the initiator of this force close, with the default
                // `IncomingBroadcastDelta`, it means we have 10 blocks left
                // when going onchain. Given we need to mine one block to
                // confirm the force close tx, and one more block to trigger
                // the sweep, we have 8 blocks left to sweep the HTLC.
                deadline := fn.Some(int32(h.htlc.RefundTimeout))

                log.Infof("%T(%x): offering second-level HTLC success tx to "+
                        "sweeper with deadline=%v, budget=%v", h,
                        h.htlc.RHash[:], h.htlc.RefundTimeout, budget)

                // We'll now offer the second-level transaction to the sweeper.
                _, err := h.Sweeper.SweepInput(
                        &secondLevelInput,
                        sweep.Params{
                                Budget:         budget,
                                DeadlineHeight: deadline,
                                Immediate:      immediate,
                        },
                )
                if err != nil {
                        return nil, err
                }

                log.Infof("%T(%x): waiting for second-level HTLC success "+
                        "transaction to confirm", h, h.htlc.RHash[:])

                // Wait for the second level transaction to confirm.
                commitSpend, err = waitForSpend(
                        &h.htlcResolution.SignedSuccessTx.TxIn[0].PreviousOutPoint,
                        h.htlcResolution.SignDetails.SignDesc.Output.PkScript,
                        h.broadcastHeight, h.Notifier, h.quit,
                )
                if err != nil {
                        return nil, err
                }

                // Now that the second-level transaction has confirmed, we
                // checkpoint the state so we'll go to the next stage in case
                // of restarts.
                h.outputIncubating = true
                if err := h.Checkpoint(h); err != nil {
                        log.Errorf("unable to Checkpoint: %v", err)
                        return nil, err
                }

                log.Infof("%T(%x): second-level HTLC success transaction "+
                        "confirmed!", h, h.htlc.RHash[:])
        }

        // If we ended up here after a restart, we must again get the
        // spend notification.
        if commitSpend == nil {
                var err error
                commitSpend, err = waitForSpend(
                        &h.htlcResolution.SignedSuccessTx.TxIn[0].PreviousOutPoint,
                        h.htlcResolution.SignDetails.SignDesc.Output.PkScript,
                        h.broadcastHeight, h.Notifier, h.quit,
                )
                if err != nil {
                        return nil, err
                }
        }

        // The HTLC success tx has a CSV lock that we must wait for, and if
        // this is a lease enforced channel and we're the imitator, we may need
        // to wait for longer.
        waitHeight := h.deriveWaitHeight(
                h.htlcResolution.CsvDelay, commitSpend,
        )

        // Now that the sweeper has broadcasted the second-level transaction,
        // it has confirmed, and we have checkpointed our state, we'll sweep
        // the second level output. We report the resolver has moved the next
        // stage.
        h.reportLock.Lock()
        h.currentReport.Stage = 2
        h.currentReport.MaturityHeight = waitHeight
        h.reportLock.Unlock()

        if h.hasCLTV() {
                log.Infof("%T(%x): waiting for CSV and CLTV lock to "+
                        "expire at height %v", h, h.htlc.RHash[:],
                        waitHeight)
        } else {
                log.Infof("%T(%x): waiting for CSV lock to expire at "+
                        "height %v", h, h.htlc.RHash[:], waitHeight)
        }

        // Deduct one block so this input is offered to the sweeper one block
        // earlier since the sweeper will wait for one block to trigger the
        // sweeping.
        //
        // TODO(yy): this is done so the outputs can be aggregated
        // properly. Suppose CSV locks of five 2nd-level outputs all
        // expire at height 840000, there is a race in block digestion
        // between contractcourt and sweeper:
        // - G1: block 840000 received in contractcourt, it now offers
        //   the outputs to the sweeper.
        // - G2: block 840000 received in sweeper, it now starts to
        //   sweep the received outputs - there's no guarantee all
        //   fives have been received.
        // To solve this, we either offer the outputs earlier, or
        // implement `blockbeat`, and force contractcourt and sweeper
        // to consume each block sequentially.
        waitHeight--

        // TODO(yy): let sweeper handles the wait?
        err := waitForHeight(waitHeight, h.Notifier, h.quit)
        if err != nil {
                return nil, err
        }

        // We'll use this input index to determine the second-level output
        // index on the transaction, as the signatures requires the indexes to
        // be the same. We don't look for the second-level output script
        // directly, as there might be more than one HTLC output to the same
        // pkScript.
        op := &wire.OutPoint{
                Hash:  *commitSpend.SpenderTxHash,
                Index: commitSpend.SpenderInputIndex,
        }

        // Let the sweeper sweep the second-level output now that the
        // CSV/CLTV locks have expired.
        var witType input.StandardWitnessType
        if isTaproot {
                witType = input.TaprootHtlcAcceptedSuccessSecondLevel
        } else {
                witType = input.HtlcAcceptedSuccessSecondLevel
        }
        inp := h.makeSweepInput(
                op, witType,
                input.LeaseHtlcAcceptedSuccessSecondLevel,
                &h.htlcResolution.SweepSignDesc,
                h.htlcResolution.CsvDelay, uint32(commitSpend.SpendingHeight),
                h.htlc.RHash,
        )

        // Calculate the budget for this sweep.
        budget := calculateBudget(
                btcutil.Amount(inp.SignDesc().Output.Value),
                h.Budget.NoDeadlineHTLCRatio,
                h.Budget.NoDeadlineHTLC,
        )

        log.Infof("%T(%x): offering second-level success tx output to sweeper "+
                "with no deadline and budget=%v at height=%v", h,
                h.htlc.RHash[:], budget, waitHeight)

        // TODO(roasbeef): need to update above for leased types
        _, err = h.Sweeper.SweepInput(
                inp,
                sweep.Params{
                        Budget: budget,

                        // For second level success tx, there's no rush to get
                        // it confirmed, so we use a nil deadline.
                        DeadlineHeight: fn.None[int32](),
                },
        )
        if err != nil {
                return nil, err
        }

        // Will return this outpoint, when this is spent the resolver is fully
        // resolved.
        return op, nil
}

// resolveRemoteCommitOutput handles sweeping an HTLC output on the remote
// commitment with the preimage. In this case we can sweep the output directly,
// and don't have to broadcast a second-level transaction.
func (h *htlcSuccessResolver) resolveRemoteCommitOutput(immediate bool) (
        ContractResolver, error) {

        isTaproot := txscript.IsPayToTaproot(
                h.htlcResolution.SweepSignDesc.Output.PkScript,
        )

        // Before we can craft out sweeping transaction, we need to
        // create an input which contains all the items required to add
        // this input to a sweeping transaction, and generate a
        // witness.
        var inp input.Input
        if isTaproot {
                inp = lnutils.Ptr(input.MakeTaprootHtlcSucceedInput(
                        &h.htlcResolution.ClaimOutpoint,
                        &h.htlcResolution.SweepSignDesc,
                        h.htlcResolution.Preimage[:],
                        h.broadcastHeight,
                        h.htlcResolution.CsvDelay,
                ))
        } else {
                inp = lnutils.Ptr(input.MakeHtlcSucceedInput(
                        &h.htlcResolution.ClaimOutpoint,
                        &h.htlcResolution.SweepSignDesc,
                        h.htlcResolution.Preimage[:],
                        h.broadcastHeight,
                        h.htlcResolution.CsvDelay,
                ))
        }

        // Calculate the budget for this sweep.
        budget := calculateBudget(
                btcutil.Amount(inp.SignDesc().Output.Value),
                h.Budget.DeadlineHTLCRatio,
                h.Budget.DeadlineHTLC,
        )

        deadline := fn.Some(int32(h.htlc.RefundTimeout))

        log.Infof("%T(%x): offering direct-preimage HTLC output to sweeper "+
                "with deadline=%v, budget=%v", h, h.htlc.RHash[:],
                h.htlc.RefundTimeout, budget)

        // We'll now offer the direct preimage HTLC to the sweeper.
        _, err := h.Sweeper.SweepInput(
                inp,
                sweep.Params{
                        Budget:         budget,
                        DeadlineHeight: deadline,
                        Immediate:      immediate,
                },
        )
        if err != nil {
                return nil, err
        }

        // Wait for the direct-preimage HTLC sweep tx to confirm.
        sweepTxDetails, err := waitForSpend(
                &h.htlcResolution.ClaimOutpoint,
                h.htlcResolution.SweepSignDesc.Output.PkScript,
                h.broadcastHeight, h.Notifier, h.quit,
        )
        if err != nil {
                return nil, err
        }

        // Once the transaction has received a sufficient number of
        // confirmations, we'll mark ourselves as fully resolved and exit.
        h.resolved = true

        // Checkpoint the resolver, and write the outcome to disk.
        return nil, h.checkpointClaim(
                sweepTxDetails.SpenderTxHash,
                channeldb.ResolverOutcomeClaimed,
        )
}

// checkpointClaim checkpoints the success resolver with the reports it needs.
// If this htlc was claimed two stages, it will write reports for both stages,
// otherwise it will just write for the single htlc claim.
func (h *htlcSuccessResolver) checkpointClaim(spendTx *chainhash.Hash,
        outcome channeldb.ResolverOutcome) error {

        // Mark the htlc as final settled.
        err := h.ChainArbitratorConfig.PutFinalHtlcOutcome(
                h.ChannelArbitratorConfig.ShortChanID, h.htlc.HtlcIndex, true,
        )
        if err != nil {
                return err
        }

        // Send notification.
        h.ChainArbitratorConfig.HtlcNotifier.NotifyFinalHtlcEvent(
                models.CircuitKey{
                        ChanID: h.ShortChanID,
                        HtlcID: h.htlc.HtlcIndex,
                },
                channeldb.FinalHtlcInfo{
                        Settled:  true,
                        Offchain: false,
                },
        )

        // Create a resolver report for claiming of the htlc itself.
        amt := btcutil.Amount(h.htlcResolution.SweepSignDesc.Output.Value)
        reports := []*channeldb.ResolverReport{
                {
                        OutPoint:        h.htlcResolution.ClaimOutpoint,
                        Amount:          amt,
                        ResolverType:    channeldb.ResolverTypeIncomingHtlc,
                        ResolverOutcome: outcome,
                        SpendTxID:       spendTx,
                },
        }

        // If we have a success tx, we append a report to represent our first
        // stage claim.
        if h.htlcResolution.SignedSuccessTx != nil {
                // If the SignedSuccessTx is not nil, we are claiming the htlc
                // in two stages, so we need to create a report for the first
                // stage transaction as well.
                spendTx := h.htlcResolution.SignedSuccessTx
                spendTxID := spendTx.TxHash()

                report := &channeldb.ResolverReport{
                        OutPoint:        spendTx.TxIn[0].PreviousOutPoint,
                        Amount:          h.htlc.Amt.ToSatoshis(),
                        ResolverType:    channeldb.ResolverTypeIncomingHtlc,
                        ResolverOutcome: channeldb.ResolverOutcomeFirstStage,
                        SpendTxID:       &spendTxID,
                }
                reports = append(reports, report)
        }

        // Finally, we checkpoint the resolver with our report(s).
        return h.Checkpoint(h, reports...)
}

// Stop signals the resolver to cancel any current resolution processes, and
// suspend.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcSuccessResolver) Stop() {
        close(h.quit)
}

// IsResolved returns true if the stored state in the resolve is fully
// resolved. In this case the target output can be forgotten.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcSuccessResolver) IsResolved() bool {
        return h.resolved
}

// report returns a report on the resolution state of the contract.
func (h *htlcSuccessResolver) report() *ContractReport {
        // If the sign details are nil, the report will be created by handled
        // by the nursery.
        if h.htlcResolution.SignDetails == nil {
                return nil
        }

        h.reportLock.Lock()
        defer h.reportLock.Unlock()
        cpy := h.currentReport
        return &cpy
}

func (h *htlcSuccessResolver) initReport() {
        // We create the initial report. This will only be reported for
        // resolvers not handled by the nursery.
        finalAmt := h.htlc.Amt.ToSatoshis()
        if h.htlcResolution.SignedSuccessTx != nil {
                finalAmt = btcutil.Amount(
                        h.htlcResolution.SignedSuccessTx.TxOut[0].Value,
                )
        }

        h.currentReport = ContractReport{
                Outpoint:       h.htlcResolution.ClaimOutpoint,
                Type:           ReportOutputIncomingHtlc,
                Amount:         finalAmt,
                MaturityHeight: h.htlcResolution.CsvDelay,
                LimboBalance:   finalAmt,
                Stage:          1,
        }
}

// Encode writes an encoded version of the ContractResolver into the passed
// Writer.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcSuccessResolver) Encode(w io.Writer) error {
        // First we'll encode our inner HTLC resolution.
        if err := encodeIncomingResolution(w, &h.htlcResolution); err != nil {
                return err
        }

        // Next, we'll write out the fields that are specified to the contract
        // resolver.
        if err := binary.Write(w, endian, h.outputIncubating); err != nil {
                return err
        }
        if err := binary.Write(w, endian, h.resolved); err != nil {
                return err
        }
        if err := binary.Write(w, endian, h.broadcastHeight); err != nil {
                return err
        }
        if _, err := w.Write(h.htlc.RHash[:]); err != nil {
                return err
        }

        // We encode the sign details last for backwards compatibility.
        err := encodeSignDetails(w, h.htlcResolution.SignDetails)
        if err != nil {
                return err
        }

        return nil
}

// newSuccessResolverFromReader attempts to decode an encoded ContractResolver
// from the passed Reader instance, returning an active ContractResolver
// instance.
func newSuccessResolverFromReader(r io.Reader, resCfg ResolverConfig) (
        *htlcSuccessResolver, error) {

        h := &htlcSuccessResolver{
                contractResolverKit: *newContractResolverKit(resCfg),
        }

        // First we'll decode our inner HTLC resolution.
        if err := decodeIncomingResolution(r, &h.htlcResolution); err != nil {
                return nil, err
        }

        // Next, we'll read all the fields that are specified to the contract
        // resolver.
        if err := binary.Read(r, endian, &h.outputIncubating); err != nil {
                return nil, err
        }
        if err := binary.Read(r, endian, &h.resolved); err != nil {
                return nil, err
        }
        if err := binary.Read(r, endian, &h.broadcastHeight); err != nil {
                return nil, err
        }
        if _, err := io.ReadFull(r, h.htlc.RHash[:]); err != nil {
                return nil, err
        }

        // Sign details is a new field that was added to the htlc resolution,
        // so it is serialized last for backwards compatibility. We try to read
        // it, but don't error out if there are not bytes left.
        signDetails, err := decodeSignDetails(r)
        if err == nil {
                h.htlcResolution.SignDetails = signDetails
        } else if err != io.EOF && err != io.ErrUnexpectedEOF {
                return nil, err
        }

        h.initReport()

        return h, nil
}

// Supplement adds additional information to the resolver that is required
// before Resolve() is called.
//
// NOTE: Part of the htlcContractResolver interface.
func (h *htlcSuccessResolver) Supplement(htlc channeldb.HTLC) {
        h.htlc = htlc
}

// HtlcPoint returns the htlc's outpoint on the commitment tx.
//
// NOTE: Part of the htlcContractResolver interface.
func (h *htlcSuccessResolver) HtlcPoint() wire.OutPoint {
        return h.htlcResolution.HtlcPoint()
}

// SupplementDeadline does nothing for an incoming htlc resolver.
//
// NOTE: Part of the htlcContractResolver interface.
func (h *htlcSuccessResolver) SupplementDeadline(_ fn.Option[int32]) {
}

// A compile time assertion to ensure htlcSuccessResolver meets the
// ContractResolver interface.
var _ htlcContractResolver = (*htlcSuccessResolver)(nil)

lightningnetwork / lnd / 11166428937

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