12199391122

Committed 06 Dec 2024 01:10PM UTC coverage: 49.807% (-9.1%) from 58.933%

Build # 12199391122

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web-flow

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Merge pull request #9337 from Guayaba221/patch-1

chore: fix typo in ruby.md

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80.23

/contractcourt/htlc_incoming_contest_resolver.go

package contractcourt

import (
        "bytes"
        "encoding/binary"
        "errors"
        "fmt"
        "io"

        "github.com/btcsuite/btcd/btcutil"
        "github.com/btcsuite/btcd/txscript"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/fn"
        "github.com/lightningnetwork/lnd/graph/db/models"
        "github.com/lightningnetwork/lnd/htlcswitch/hop"
        "github.com/lightningnetwork/lnd/invoices"
        "github.com/lightningnetwork/lnd/lntypes"
        "github.com/lightningnetwork/lnd/lnwallet"
        "github.com/lightningnetwork/lnd/lnwire"
        "github.com/lightningnetwork/lnd/queue"
)

// htlcIncomingContestResolver is a ContractResolver that's able to resolve an
// incoming HTLC that is still contested. An HTLC is still contested, if at the
// time of commitment broadcast, we don't know of the preimage for it yet, and
// it hasn't expired. In this case, we can resolve the HTLC if we learn of the
// preimage, otherwise the remote party will sweep it after it expires.
//
// TODO(roasbeef): just embed the other resolver?
type htlcIncomingContestResolver struct {
        // htlcExpiry is the absolute expiry of this incoming HTLC. We use this
        // value to determine if we can exit early as if the HTLC times out,
        // before we learn of the preimage then we can't claim it on chain
        // successfully.
        htlcExpiry uint32

        // htlcSuccessResolver is the inner resolver that may be utilized if we
        // learn of the preimage.
        *htlcSuccessResolver
}

// newIncomingContestResolver instantiates a new incoming htlc contest resolver.
func newIncomingContestResolver(
        res lnwallet.IncomingHtlcResolution, broadcastHeight uint32,
        htlc channeldb.HTLC, resCfg ResolverConfig) *htlcIncomingContestResolver {

        success := newSuccessResolver(
                res, broadcastHeight, htlc, resCfg,
        )

        return &htlcIncomingContestResolver{
                htlcExpiry:          htlc.RefundTimeout,
                htlcSuccessResolver: success,
        }
}

func (h *htlcIncomingContestResolver) processFinalHtlcFail() error {
        // Mark the htlc as final failed.
        err := h.ChainArbitratorConfig.PutFinalHtlcOutcome(
                h.ChannelArbitratorConfig.ShortChanID, h.htlc.HtlcIndex, false,
        )
        if err != nil {
                return err
        }

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

        return nil
}

// Resolve attempts to resolve this contract. As we don't yet know of the
// preimage for the contract, we'll wait for one of two things to happen:
//
//  1. We learn of the preimage! In this case, we can sweep the HTLC incoming
//     and ensure that if this was a multi-hop HTLC we are made whole. In this
//     case, an additional ContractResolver will be returned to finish the
//     job.
//
//  2. The HTLC expires. If this happens, then the contract is fully resolved
//     as we have no remaining actions left at our disposal.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcIncomingContestResolver) Resolve(
        _ bool) (ContractResolver, error) {

        // If we're already full resolved, then we don't have anything further
        // to do.
        if h.resolved {
                return nil, nil
        }

        // First try to parse the payload. If that fails, we can stop resolution
        // now.
        payload, nextHopOnionBlob, err := h.decodePayload()
        if err != nil {
                log.Debugf("ChannelArbitrator(%v): cannot decode payload of "+
                        "htlc %v", h.ChanPoint, h.HtlcPoint())

                // If we've locked in an htlc with an invalid payload on our
                // commitment tx, we don't need to resolve it. The other party
                // will time it out and get their funds back. This situation
                // can present itself when we crash before processRemoteAdds in
                // the link has ran.
                h.resolved = true

                if err := h.processFinalHtlcFail(); err != nil {
                        return nil, err
                }

                // We write a report to disk that indicates we could not decode
                // the htlc.
                resReport := h.report().resolverReport(
                        nil, channeldb.ResolverTypeIncomingHtlc,
                        channeldb.ResolverOutcomeAbandoned,
                )
                return nil, h.PutResolverReport(nil, resReport)
        }

        // Register for block epochs. After registration, the current height
        // will be sent on the channel immediately.
        blockEpochs, err := h.Notifier.RegisterBlockEpochNtfn(nil)
        if err != nil {
                return nil, err
        }
        defer blockEpochs.Cancel()

        var currentHeight int32
        select {
        case newBlock, ok := <-blockEpochs.Epochs:
                if !ok {
                        return nil, errResolverShuttingDown
                }
                currentHeight = newBlock.Height
        case <-h.quit:
                return nil, errResolverShuttingDown
        }

        log.Debugf("%T(%v): Resolving incoming HTLC(expiry=%v, height=%v)", h,
                h.htlcResolution.ClaimOutpoint, h.htlcExpiry, currentHeight)

        // We'll first check if this HTLC has been timed out, if so, we can
        // return now and mark ourselves as resolved. If we're past the point of
        // expiry of the HTLC, then at this point the sender can sweep it, so
        // we'll end our lifetime. Here we deliberately forego the chance that
        // the sender doesn't sweep and we already have or will learn the
        // preimage. Otherwise the resolver could potentially stay active
        // indefinitely and the channel will never close properly.
        if uint32(currentHeight) >= h.htlcExpiry {
                // TODO(roasbeef): should also somehow check if outgoing is
                // resolved or not
                //  * may need to hook into the circuit map
                //  * can't timeout before the outgoing has been

                log.Infof("%T(%v): HTLC has timed out (expiry=%v, height=%v), "+
                        "abandoning", h, h.htlcResolution.ClaimOutpoint,
                        h.htlcExpiry, currentHeight)
                h.resolved = true

                if err := h.processFinalHtlcFail(); err != nil {
                        return nil, err
                }

                // Finally, get our report and checkpoint our resolver with a
                // timeout outcome report.
                report := h.report().resolverReport(
                        nil, channeldb.ResolverTypeIncomingHtlc,
                        channeldb.ResolverOutcomeTimeout,
                )
                return nil, h.Checkpoint(h, report)
        }

        // applyPreimage is a helper function that will populate our internal
        // resolver with the preimage we learn of. This should be called once
        // the preimage is revealed so the inner resolver can properly complete
        // its duties. The error return value indicates whether the preimage
        // was properly applied.
        applyPreimage := func(preimage lntypes.Preimage) error {
                // Sanity check to see if this preimage matches our htlc. At
                // this point it should never happen that it does not match.
                if !preimage.Matches(h.htlc.RHash) {
                        return errors.New("preimage does not match hash")
                }

                // Update htlcResolution with the matching preimage.
                h.htlcResolution.Preimage = preimage

                log.Infof("%T(%v): applied preimage=%v", h,
                        h.htlcResolution.ClaimOutpoint, preimage)

                isSecondLevel := h.htlcResolution.SignedSuccessTx != nil

                // If we didn't have to go to the second level to claim (this
                // is the remote commitment transaction), then we don't need to
                // modify our canned witness.
                if !isSecondLevel {
                        return nil
                }

                isTaproot := txscript.IsPayToTaproot(
                        h.htlcResolution.SignedSuccessTx.TxOut[0].PkScript,
                )

                // If this is our commitment transaction, then we'll need to
                // populate the witness for the second-level HTLC transaction.
                switch {
                // For taproot channels, the witness for sweeping with success
                // looks like:
                //   - <sender sig> <receiver sig> <preimage> <success_script>
                //     <control_block>
                //
                // So we'll insert it at the 3rd index of the witness.
                case isTaproot:
                        //nolint:ll
                        h.htlcResolution.SignedSuccessTx.TxIn[0].Witness[2] = preimage[:]

                // Within the witness for the success transaction, the
                // preimage is the 4th element as it looks like:
                //
                //  * <0> <sender sig> <recvr sig> <preimage> <witness script>
                //
                // We'll populate it within the witness, as since this
                // was a "contest" resolver, we didn't yet know of the
                // preimage.
                case !isTaproot:
                        h.htlcResolution.SignedSuccessTx.TxIn[0].Witness[3] = preimage[:]
                }

                return nil
        }

        // Define a closure to process htlc resolutions either directly or
        // triggered by future notifications.
        processHtlcResolution := func(e invoices.HtlcResolution) (
                ContractResolver, error) {

                // Take action based on the type of resolution we have
                // received.
                switch resolution := e.(type) {
                // If the htlc resolution was a settle, apply the
                // preimage and return a success resolver.
                case *invoices.HtlcSettleResolution:
                        err := applyPreimage(resolution.Preimage)
                        if err != nil {
                                return nil, err
                        }

                        return h.htlcSuccessResolver, nil

                // If the htlc was failed, mark the htlc as
                // resolved.
                case *invoices.HtlcFailResolution:
                        log.Infof("%T(%v): Exit hop HTLC canceled "+
                                "(expiry=%v, height=%v), abandoning", h,
                                h.htlcResolution.ClaimOutpoint,
                                h.htlcExpiry, currentHeight)

                        h.resolved = true

                        if err := h.processFinalHtlcFail(); err != nil {
                                return nil, err
                        }

                        // Checkpoint our resolver with an abandoned outcome
                        // because we take no further action on this htlc.
                        report := h.report().resolverReport(
                                nil, channeldb.ResolverTypeIncomingHtlc,
                                channeldb.ResolverOutcomeAbandoned,
                        )
                        return nil, h.Checkpoint(h, report)

                // Error if the resolution type is unknown, we are only
                // expecting settles and fails.
                default:
                        return nil, fmt.Errorf("unknown resolution"+
                                " type: %v", e)
                }
        }

        var (
                hodlChan       <-chan interface{}
                witnessUpdates <-chan lntypes.Preimage
        )
        if payload.FwdInfo.NextHop == hop.Exit {
                // Create a buffered hodl chan to prevent deadlock.
                hodlQueue := queue.NewConcurrentQueue(10)
                hodlQueue.Start()

                hodlChan = hodlQueue.ChanOut()

                // Notify registry that we are potentially resolving as an exit
                // hop on-chain. If this HTLC indeed pays to an existing
                // invoice, the invoice registry will tell us what to do with
                // the HTLC. This is identical to HTLC resolution in the link.
                circuitKey := models.CircuitKey{
                        ChanID: h.ShortChanID,
                        HtlcID: h.htlc.HtlcIndex,
                }

                resolution, err := h.Registry.NotifyExitHopHtlc(
                        h.htlc.RHash, h.htlc.Amt, h.htlcExpiry, currentHeight,
                        circuitKey, hodlQueue.ChanIn(), nil, payload,
                )
                if err != nil {
                        return nil, err
                }

                defer func() {
                        h.Registry.HodlUnsubscribeAll(hodlQueue.ChanIn())

                        hodlQueue.Stop()
                }()

                // Take action based on the resolution we received. If the htlc
                // was settled, or a htlc for a known invoice failed we can
                // resolve it directly. If the resolution is nil, the htlc was
                // neither accepted nor failed, so we cannot take action yet.
                switch res := resolution.(type) {
                case *invoices.HtlcFailResolution:
                        // In the case where the htlc failed, but the invoice
                        // was known to the registry, we can directly resolve
                        // the htlc.
                        if res.Outcome != invoices.ResultInvoiceNotFound {
                                return processHtlcResolution(resolution)
                        }

                // If we settled the htlc, we can resolve it.
                case *invoices.HtlcSettleResolution:
                        return processHtlcResolution(resolution)

                // If the resolution is nil, the htlc was neither settled nor
                // failed so we cannot take action at present.
                case nil:

                default:
                        return nil, fmt.Errorf("unknown htlc resolution type: %T",
                                resolution)
                }
        } else {
                // If the HTLC hasn't expired yet, then we may still be able to
                // claim it if we learn of the pre-image, so we'll subscribe to
                // the preimage database to see if it turns up, or the HTLC
                // times out.
                //
                // NOTE: This is done BEFORE opportunistically querying the db,
                // to ensure the preimage can't be delivered between querying
                // and registering for the preimage subscription.
                preimageSubscription, err := h.PreimageDB.SubscribeUpdates(
                        h.htlcSuccessResolver.ShortChanID, &h.htlc,
                        payload, nextHopOnionBlob,
                )
                if err != nil {
                        return nil, err
                }
                defer preimageSubscription.CancelSubscription()

                // With the epochs and preimage subscriptions initialized, we'll
                // query to see if we already know the preimage.
                preimage, ok := h.PreimageDB.LookupPreimage(h.htlc.RHash)
                if ok {
                        // If we do, then this means we can claim the HTLC!
                        // However, we don't know how to ourselves, so we'll
                        // return our inner resolver which has the knowledge to
                        // do so.
                        if err := applyPreimage(preimage); err != nil {
                                return nil, err
                        }

                        return h.htlcSuccessResolver, nil
                }

                witnessUpdates = preimageSubscription.WitnessUpdates
        }

        for {
                select {
                case preimage := <-witnessUpdates:
                        // We received a new preimage, but we need to ignore
                        // all except the preimage we are waiting for.
                        if !preimage.Matches(h.htlc.RHash) {
                                continue
                        }

                        if err := applyPreimage(preimage); err != nil {
                                return nil, err
                        }

                        // We've learned of the preimage and this information
                        // has been added to our inner resolver. We return it so
                        // it can continue contract resolution.
                        return h.htlcSuccessResolver, nil

                case hodlItem := <-hodlChan:
                        htlcResolution := hodlItem.(invoices.HtlcResolution)
                        return processHtlcResolution(htlcResolution)

                case newBlock, ok := <-blockEpochs.Epochs:
                        if !ok {
                                return nil, errResolverShuttingDown
                        }

                        // If this new height expires the HTLC, then this means
                        // we never found out the preimage, so we can mark
                        // resolved and exit.
                        newHeight := uint32(newBlock.Height)
                        if newHeight >= h.htlcExpiry {
                                log.Infof("%T(%v): HTLC has timed out "+
                                        "(expiry=%v, height=%v), abandoning", h,
                                        h.htlcResolution.ClaimOutpoint,
                                        h.htlcExpiry, currentHeight)
                                h.resolved = true

                                if err := h.processFinalHtlcFail(); err != nil {
                                        return nil, err
                                }

                                report := h.report().resolverReport(
                                        nil,
                                        channeldb.ResolverTypeIncomingHtlc,
                                        channeldb.ResolverOutcomeTimeout,
                                )
                                return nil, h.Checkpoint(h, report)
                        }

                case <-h.quit:
                        return nil, errResolverShuttingDown
                }
        }
}

// report returns a report on the resolution state of the contract.
func (h *htlcIncomingContestResolver) report() *ContractReport {
        // No locking needed as these values are read-only.

        finalAmt := h.htlc.Amt.ToSatoshis()
        if h.htlcResolution.SignedSuccessTx != nil {
                finalAmt = btcutil.Amount(
                        h.htlcResolution.SignedSuccessTx.TxOut[0].Value,
                )
        }

        return &ContractReport{
                Outpoint:       h.htlcResolution.ClaimOutpoint,
                Type:           ReportOutputIncomingHtlc,
                Amount:         finalAmt,
                MaturityHeight: h.htlcExpiry,
                LimboBalance:   finalAmt,
                Stage:          1,
        }
}

// Stop signals the resolver to cancel any current resolution processes, and
// suspend.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcIncomingContestResolver) 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 *htlcIncomingContestResolver) IsResolved() bool {
        return h.resolved
}

// Encode writes an encoded version of the ContractResolver into the passed
// Writer.
//
// NOTE: Part of the ContractResolver interface.
func (h *htlcIncomingContestResolver) Encode(w io.Writer) error {
        // We'll first write out the one field unique to this resolver.
        if err := binary.Write(w, endian, h.htlcExpiry); err != nil {
                return err
        }

        // Then we'll write out our internal resolver.
        return h.htlcSuccessResolver.Encode(w)
}

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

        h := &htlcIncomingContestResolver{}

        // We'll first read the one field unique to this resolver.
        if err := binary.Read(r, endian, &h.htlcExpiry); err != nil {
                return nil, err
        }

        // Then we'll decode our internal resolver.
        successResolver, err := newSuccessResolverFromReader(r, resCfg)
        if err != nil {
                return nil, err
        }
        h.htlcSuccessResolver = successResolver

        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 *htlcIncomingContestResolver) Supplement(htlc channeldb.HTLC) {
        h.htlc = htlc
}

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

// decodePayload (re)decodes the hop payload of a received htlc.
func (h *htlcIncomingContestResolver) decodePayload() (*hop.Payload,
        []byte, error) {

        blindingInfo := hop.ReconstructBlindingInfo{
                IncomingAmt:    h.htlc.Amt,
                IncomingExpiry: h.htlc.RefundTimeout,
                BlindingKey:    h.htlc.BlindingPoint,
        }

        onionReader := bytes.NewReader(h.htlc.OnionBlob[:])
        iterator, err := h.OnionProcessor.ReconstructHopIterator(
                onionReader, h.htlc.RHash[:], blindingInfo,
        )
        if err != nil {
                return nil, nil, err
        }

        payload, _, err := iterator.HopPayload()
        if err != nil {
                return nil, nil, err
        }

        // Transform onion blob for the next hop.
        var onionBlob [lnwire.OnionPacketSize]byte
        buf := bytes.NewBuffer(onionBlob[0:0])
        err = iterator.EncodeNextHop(buf)
        if err != nil {
                return nil, nil, err
        }

        return payload, onionBlob[:], nil
}

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

1	package contractcourt
2
3	import (
4	"bytes"
5	"encoding/binary"
6	"errors"
7	"fmt"
8	"io"
9
10	"github.com/btcsuite/btcd/btcutil"
11	"github.com/btcsuite/btcd/txscript"
12	"github.com/lightningnetwork/lnd/channeldb"
13	"github.com/lightningnetwork/lnd/fn"
14	"github.com/lightningnetwork/lnd/graph/db/models"
15	"github.com/lightningnetwork/lnd/htlcswitch/hop"
16	"github.com/lightningnetwork/lnd/invoices"
17	"github.com/lightningnetwork/lnd/lntypes"
18	"github.com/lightningnetwork/lnd/lnwallet"
19	"github.com/lightningnetwork/lnd/lnwire"
20	"github.com/lightningnetwork/lnd/queue"
21	)
22
23	// htlcIncomingContestResolver is a ContractResolver that's able to resolve an
24	// incoming HTLC that is still contested. An HTLC is still contested, if at the
25	// time of commitment broadcast, we don't know of the preimage for it yet, and
26	// it hasn't expired. In this case, we can resolve the HTLC if we learn of the
27	// preimage, otherwise the remote party will sweep it after it expires.
28	//
29	// TODO(roasbeef): just embed the other resolver?
30	type htlcIncomingContestResolver struct {
31	// htlcExpiry is the absolute expiry of this incoming HTLC. We use this
32	// value to determine if we can exit early as if the HTLC times out,
33	// before we learn of the preimage then we can't claim it on chain
34	// successfully.
35	htlcExpiry uint32
36
37	// htlcSuccessResolver is the inner resolver that may be utilized if we
38	// learn of the preimage.
39	*htlcSuccessResolver
40	}
41
42	// newIncomingContestResolver instantiates a new incoming htlc contest resolver.
43	func newIncomingContestResolver(
44	res lnwallet.IncomingHtlcResolution, broadcastHeight uint32,
45	htlc channeldb.HTLC, resCfg ResolverConfig) *htlcIncomingContestResolver {	4✔
46		4✔
47	success := newSuccessResolver(	4✔
48	res, broadcastHeight, htlc, resCfg,	4✔
49	)	4✔
50		4✔
51	return &htlcIncomingContestResolver{	4✔
52	htlcExpiry: htlc.RefundTimeout,	4✔
53	htlcSuccessResolver: success,	4✔
54	}	4✔
55	}	4✔
56
57	func (h *htlcIncomingContestResolver) processFinalHtlcFail() error {	4✔
58	// Mark the htlc as final failed.	4✔
59	err := h.ChainArbitratorConfig.PutFinalHtlcOutcome(	4✔
60	h.ChannelArbitratorConfig.ShortChanID, h.htlc.HtlcIndex, false,	4✔
61	)	4✔
62	if err != nil {	4✔
63	return err	×
64	}	×
65
66	// Send notification.
67	h.ChainArbitratorConfig.HtlcNotifier.NotifyFinalHtlcEvent(	4✔
68	models.CircuitKey{	4✔
69	ChanID: h.ShortChanID,	4✔
70	HtlcID: h.htlc.HtlcIndex,	4✔
71	},	4✔
72	channeldb.FinalHtlcInfo{	4✔
73	Settled: false,	4✔
74	Offchain: false,	4✔
75	},	4✔
76	)	4✔
77		4✔
78	return nil	4✔
79	}
80
81	// Resolve attempts to resolve this contract. As we don't yet know of the
82	// preimage for the contract, we'll wait for one of two things to happen:
83	//
84	// 1. We learn of the preimage! In this case, we can sweep the HTLC incoming
85	// and ensure that if this was a multi-hop HTLC we are made whole. In this
86	// case, an additional ContractResolver will be returned to finish the
87	// job.
88	//
89	// 2. The HTLC expires. If this happens, then the contract is fully resolved
90	// as we have no remaining actions left at our disposal.
91	//
92	// NOTE: Part of the ContractResolver interface.
93	func (h *htlcIncomingContestResolver) Resolve(
94	_ bool) (ContractResolver, error) {	4✔
95		4✔
96	// If we're already full resolved, then we don't have anything further	4✔
97	// to do.	4✔
98	if h.resolved {	4✔
99	return nil, nil	×
100	}	×
101
102	// First try to parse the payload. If that fails, we can stop resolution
103	// now.
104	payload, nextHopOnionBlob, err := h.decodePayload()	4✔
105	if err != nil {	4✔
106	log.Debugf("ChannelArbitrator(%v): cannot decode payload of "+	×
107	"htlc %v", h.ChanPoint, h.HtlcPoint())	×
108		×
109	// If we've locked in an htlc with an invalid payload on our	×
110	// commitment tx, we don't need to resolve it. The other party	×
111	// will time it out and get their funds back. This situation	×
112	// can present itself when we crash before processRemoteAdds in	×
113	// the link has ran.	×
114	h.resolved = true	×
115		×
116	if err := h.processFinalHtlcFail(); err != nil {	×
117	return nil, err	×
118	}	×
119
120	// We write a report to disk that indicates we could not decode
121	// the htlc.
122	resReport := h.report().resolverReport(	×
123	nil, channeldb.ResolverTypeIncomingHtlc,	×
124	channeldb.ResolverOutcomeAbandoned,	×
125	)	×
126	return nil, h.PutResolverReport(nil, resReport)	×
127	}
128
129	// Register for block epochs. After registration, the current height
130	// will be sent on the channel immediately.
131	blockEpochs, err := h.Notifier.RegisterBlockEpochNtfn(nil)	4✔
132	if err != nil {	4✔
133	return nil, err	×
134	}	×
135	defer blockEpochs.Cancel()	4✔
136		4✔
137	var currentHeight int32	4✔
138	select {	4✔
139	case newBlock, ok := <-blockEpochs.Epochs:	4✔
140	if !ok {	4✔
141	return nil, errResolverShuttingDown	×
142	}	×
143	currentHeight = newBlock.Height	4✔
144	case <-h.quit:	×
145	return nil, errResolverShuttingDown	×
146	}
147
148	log.Debugf("%T(%v): Resolving incoming HTLC(expiry=%v, height=%v)", h,	4✔
149	h.htlcResolution.ClaimOutpoint, h.htlcExpiry, currentHeight)	4✔
150		4✔
151	// We'll first check if this HTLC has been timed out, if so, we can	4✔
152	// return now and mark ourselves as resolved. If we're past the point of	4✔
153	// expiry of the HTLC, then at this point the sender can sweep it, so	4✔
154	// we'll end our lifetime. Here we deliberately forego the chance that	4✔
155	// the sender doesn't sweep and we already have or will learn the	4✔
156	// preimage. Otherwise the resolver could potentially stay active	4✔
157	// indefinitely and the channel will never close properly.	4✔
158	if uint32(currentHeight) >= h.htlcExpiry {	8✔
159	// TODO(roasbeef): should also somehow check if outgoing is	4✔
160	// resolved or not	4✔
161	// * may need to hook into the circuit map	4✔
162	// * can't timeout before the outgoing has been	4✔
163		4✔
164	log.Infof("%T(%v): HTLC has timed out (expiry=%v, height=%v), "+	4✔
165	"abandoning", h, h.htlcResolution.ClaimOutpoint,	4✔
166	h.htlcExpiry, currentHeight)	4✔
167	h.resolved = true	4✔
168		4✔
169	if err := h.processFinalHtlcFail(); err != nil {	4✔
170	return nil, err	×
171	}	×
172
173	// Finally, get our report and checkpoint our resolver with a
174	// timeout outcome report.
175	report := h.report().resolverReport(	4✔
176	nil, channeldb.ResolverTypeIncomingHtlc,	4✔
177	channeldb.ResolverOutcomeTimeout,	4✔
178	)	4✔
179	return nil, h.Checkpoint(h, report)	4✔
180	}
181
182	// applyPreimage is a helper function that will populate our internal
183	// resolver with the preimage we learn of. This should be called once
184	// the preimage is revealed so the inner resolver can properly complete
185	// its duties. The error return value indicates whether the preimage
186	// was properly applied.
187	applyPreimage := func(preimage lntypes.Preimage) error {	8✔
188	// Sanity check to see if this preimage matches our htlc. At	4✔
189	// this point it should never happen that it does not match.	4✔
190	if !preimage.Matches(h.htlc.RHash) {	4✔
191	return errors.New("preimage does not match hash")	×
192	}	×
193
194	// Update htlcResolution with the matching preimage.
195	h.htlcResolution.Preimage = preimage	4✔
196		4✔
197	log.Infof("%T(%v): applied preimage=%v", h,	4✔
198	h.htlcResolution.ClaimOutpoint, preimage)	4✔
199		4✔
200	isSecondLevel := h.htlcResolution.SignedSuccessTx != nil	4✔
201		4✔
202	// If we didn't have to go to the second level to claim (this	4✔
203	// is the remote commitment transaction), then we don't need to	4✔
204	// modify our canned witness.	4✔
205	if !isSecondLevel {	8✔
206	return nil	4✔
207	}	4✔
208
209	isTaproot := txscript.IsPayToTaproot(	4✔
210	h.htlcResolution.SignedSuccessTx.TxOut[0].PkScript,	4✔
211	)	4✔
212		4✔
213	// If this is our commitment transaction, then we'll need to	4✔
214	// populate the witness for the second-level HTLC transaction.	4✔
215	switch {	4✔
216	// For taproot channels, the witness for sweeping with success
217	// looks like:
218	// - <sender sig> <receiver sig> <preimage> <success_script>
219	// <control_block>
220	//
221	// So we'll insert it at the 3rd index of the witness.
222	case isTaproot:	4✔
223	//nolint:ll	4✔
224	h.htlcResolution.SignedSuccessTx.TxIn[0].Witness[2] = preimage[:]	4✔
225
226	// Within the witness for the success transaction, the
227	// preimage is the 4th element as it looks like:
228	//
229	// * <0> <sender sig> <recvr sig> <preimage> <witness script>
230	//
231	// We'll populate it within the witness, as since this
232	// was a "contest" resolver, we didn't yet know of the
233	// preimage.
234	case !isTaproot:	4✔
235	h.htlcResolution.SignedSuccessTx.TxIn[0].Witness[3] = preimage[:]	4✔
236	}
237
238	return nil	4✔
239	}
240
241	// Define a closure to process htlc resolutions either directly or
242	// triggered by future notifications.
243	processHtlcResolution := func(e invoices.HtlcResolution) (	4✔
244	ContractResolver, error) {	8✔
245		4✔
246	// Take action based on the type of resolution we have	4✔
247	// received.	4✔
248	switch resolution := e.(type) {	4✔
249	// If the htlc resolution was a settle, apply the
250	// preimage and return a success resolver.
251	case *invoices.HtlcSettleResolution:	4✔
252	err := applyPreimage(resolution.Preimage)	4✔
253	if err != nil {	4✔
254	return nil, err	×
255	}	×
256
257	return h.htlcSuccessResolver, nil	4✔
258
259	// If the htlc was failed, mark the htlc as
260	// resolved.
261	case *invoices.HtlcFailResolution:	4✔
262	log.Infof("%T(%v): Exit hop HTLC canceled "+	4✔
263	"(expiry=%v, height=%v), abandoning", h,	4✔
264	h.htlcResolution.ClaimOutpoint,	4✔
265	h.htlcExpiry, currentHeight)	4✔
266		4✔
267	h.resolved = true	4✔
268		4✔
269	if err := h.processFinalHtlcFail(); err != nil {	4✔
270	return nil, err	×
271	}	×
272
273	// Checkpoint our resolver with an abandoned outcome
274	// because we take no further action on this htlc.
275	report := h.report().resolverReport(	4✔
276	nil, channeldb.ResolverTypeIncomingHtlc,	4✔
277	channeldb.ResolverOutcomeAbandoned,	4✔
278	)	4✔
279	return nil, h.Checkpoint(h, report)	4✔
280
281	// Error if the resolution type is unknown, we are only
282	// expecting settles and fails.
283	default:	×
284	return nil, fmt.Errorf("unknown resolution"+	×
285	" type: %v", e)	×
286	}
287	}
288
289	var (	4✔
290	hodlChan <-chan interface{}	4✔
291	witnessUpdates <-chan lntypes.Preimage	4✔
292	)	4✔
293	if payload.FwdInfo.NextHop == hop.Exit {	8✔
294	// Create a buffered hodl chan to prevent deadlock.	4✔
295	hodlQueue := queue.NewConcurrentQueue(10)	4✔
296	hodlQueue.Start()	4✔
297		4✔
298	hodlChan = hodlQueue.ChanOut()	4✔
299		4✔
300	// Notify registry that we are potentially resolving as an exit	4✔
301	// hop on-chain. If this HTLC indeed pays to an existing	4✔
302	// invoice, the invoice registry will tell us what to do with	4✔
303	// the HTLC. This is identical to HTLC resolution in the link.	4✔
304	circuitKey := models.CircuitKey{	4✔
305	ChanID: h.ShortChanID,	4✔
306	HtlcID: h.htlc.HtlcIndex,	4✔
307	}	4✔
308		4✔
309	resolution, err := h.Registry.NotifyExitHopHtlc(	4✔
310	h.htlc.RHash, h.htlc.Amt, h.htlcExpiry, currentHeight,	4✔
311	circuitKey, hodlQueue.ChanIn(), nil, payload,	4✔
312	)	4✔
313	if err != nil {	4✔
314	return nil, err	×
315	}	×
316
317	defer func() {	8✔
318	h.Registry.HodlUnsubscribeAll(hodlQueue.ChanIn())	4✔
319		4✔
320	hodlQueue.Stop()	4✔
321	}()	4✔
322
323	// Take action based on the resolution we received. If the htlc
324	// was settled, or a htlc for a known invoice failed we can
325	// resolve it directly. If the resolution is nil, the htlc was
326	// neither accepted nor failed, so we cannot take action yet.
327	switch res := resolution.(type) {	4✔
328	case *invoices.HtlcFailResolution:	4✔
329	// In the case where the htlc failed, but the invoice	4✔
330	// was known to the registry, we can directly resolve	4✔
331	// the htlc.	4✔
332	if res.Outcome != invoices.ResultInvoiceNotFound {	4✔
333	return processHtlcResolution(resolution)	×
334	}	×
335
336	// If we settled the htlc, we can resolve it.
337	case *invoices.HtlcSettleResolution:	4✔
338	return processHtlcResolution(resolution)	4✔
339
340	// If the resolution is nil, the htlc was neither settled nor
341	// failed so we cannot take action at present.
342	case nil:	4✔
343
344	default:	×
345	return nil, fmt.Errorf("unknown htlc resolution type: %T",	×
346	resolution)	×
347	}
348	} else {	4✔
349	// If the HTLC hasn't expired yet, then we may still be able to	4✔
350	// claim it if we learn of the pre-image, so we'll subscribe to	4✔
351	// the preimage database to see if it turns up, or the HTLC	4✔
352	// times out.	4✔
353	//	4✔
354	// NOTE: This is done BEFORE opportunistically querying the db,	4✔
355	// to ensure the preimage can't be delivered between querying	4✔
356	// and registering for the preimage subscription.	4✔
357	preimageSubscription, err := h.PreimageDB.SubscribeUpdates(	4✔
358	h.htlcSuccessResolver.ShortChanID, &h.htlc,	4✔
359	payload, nextHopOnionBlob,	4✔
360	)	4✔
361	if err != nil {	4✔
362	return nil, err	×
363	}	×
364	defer preimageSubscription.CancelSubscription()	4✔
365		4✔
366	// With the epochs and preimage subscriptions initialized, we'll	4✔
367	// query to see if we already know the preimage.	4✔
368	preimage, ok := h.PreimageDB.LookupPreimage(h.htlc.RHash)	4✔
369	if ok {	8✔
370	// If we do, then this means we can claim the HTLC!	4✔
371	// However, we don't know how to ourselves, so we'll	4✔
372	// return our inner resolver which has the knowledge to	4✔
373	// do so.	4✔
374	if err := applyPreimage(preimage); err != nil {	4✔
375	return nil, err	×
376	}	×
377
378	return h.htlcSuccessResolver, nil	4✔
379	}
380
381	witnessUpdates = preimageSubscription.WitnessUpdates	4✔
382	}
383
384	for {	8✔
385	select {	4✔
386	case preimage := <-witnessUpdates:	4✔
387	// We received a new preimage, but we need to ignore	4✔
388	// all except the preimage we are waiting for.	4✔
389	if !preimage.Matches(h.htlc.RHash) {	8✔
390	continue	4✔
391	}
392
393	if err := applyPreimage(preimage); err != nil {	4✔
394	return nil, err	×
395	}	×
396
397	// We've learned of the preimage and this information
398	// has been added to our inner resolver. We return it so
399	// it can continue contract resolution.
400	return h.htlcSuccessResolver, nil	4✔
401
402	case hodlItem := <-hodlChan:	4✔
403	htlcResolution := hodlItem.(invoices.HtlcResolution)	4✔
404	return processHtlcResolution(htlcResolution)	4✔
405
406	case newBlock, ok := <-blockEpochs.Epochs:	4✔
407	if !ok {	4✔
408	return nil, errResolverShuttingDown	×
409	}	×
410
411	// If this new height expires the HTLC, then this means
412	// we never found out the preimage, so we can mark
413	// resolved and exit.
414	newHeight := uint32(newBlock.Height)	4✔
415	if newHeight >= h.htlcExpiry {	8✔
416	log.Infof("%T(%v): HTLC has timed out "+	4✔
417	"(expiry=%v, height=%v), abandoning", h,	4✔
418	h.htlcResolution.ClaimOutpoint,	4✔
419	h.htlcExpiry, currentHeight)	4✔
420	h.resolved = true	4✔
421		4✔
422	if err := h.processFinalHtlcFail(); err != nil {	4✔
423	return nil, err	×
424	}	×
425
426	report := h.report().resolverReport(	4✔
427	nil,	4✔
428	channeldb.ResolverTypeIncomingHtlc,	4✔
429	channeldb.ResolverOutcomeTimeout,	4✔
430	)	4✔
431	return nil, h.Checkpoint(h, report)	4✔
432	}
433
434	case <-h.quit:	4✔
435	return nil, errResolverShuttingDown	4✔
436	}
437	}
438	}
439
440	// report returns a report on the resolution state of the contract.
441	func (h htlcIncomingContestResolver) report() ContractReport {	4✔
442	// No locking needed as these values are read-only.	4✔
443		4✔
444	finalAmt := h.htlc.Amt.ToSatoshis()	4✔
445	if h.htlcResolution.SignedSuccessTx != nil {	8✔
446	finalAmt = btcutil.Amount(	4✔
447	h.htlcResolution.SignedSuccessTx.TxOut[0].Value,	4✔
448	)	4✔
449	}	4✔
450
451	return &ContractReport{	4✔
452	Outpoint: h.htlcResolution.ClaimOutpoint,	4✔
453	Type: ReportOutputIncomingHtlc,	4✔
454	Amount: finalAmt,	4✔
455	MaturityHeight: h.htlcExpiry,	4✔
456	LimboBalance: finalAmt,	4✔
457	Stage: 1,	4✔
458	}	4✔
459	}
460
461	// Stop signals the resolver to cancel any current resolution processes, and
462	// suspend.
463	//
464	// NOTE: Part of the ContractResolver interface.
465	func (h *htlcIncomingContestResolver) Stop() {	4✔
466	close(h.quit)	4✔
467	}	4✔
468
469	// IsResolved returns true if the stored state in the resolve is fully
470	// resolved. In this case the target output can be forgotten.
471	//
472	// NOTE: Part of the ContractResolver interface.
473	func (h *htlcIncomingContestResolver) IsResolved() bool {	4✔
474	return h.resolved	4✔
475	}	4✔
476
477	// Encode writes an encoded version of the ContractResolver into the passed
478	// Writer.
479	//
480	// NOTE: Part of the ContractResolver interface.
481	func (h *htlcIncomingContestResolver) Encode(w io.Writer) error {	4✔
482	// We'll first write out the one field unique to this resolver.	4✔
483	if err := binary.Write(w, endian, h.htlcExpiry); err != nil {	4✔
484	return err	×
485	}	×
486
487	// Then we'll write out our internal resolver.
488	return h.htlcSuccessResolver.Encode(w)	4✔
489	}
490
491	// newIncomingContestResolverFromReader attempts to decode an encoded ContractResolver
492	// from the passed Reader instance, returning an active ContractResolver
493	// instance.
494	func newIncomingContestResolverFromReader(r io.Reader, resCfg ResolverConfig) (
495	*htlcIncomingContestResolver, error) {	4✔
496		4✔
497	h := &htlcIncomingContestResolver{}	4✔
498		4✔
499	// We'll first read the one field unique to this resolver.	4✔
500	if err := binary.Read(r, endian, &h.htlcExpiry); err != nil {	4✔
501	return nil, err	×
502	}	×
503
504	// Then we'll decode our internal resolver.
505	successResolver, err := newSuccessResolverFromReader(r, resCfg)	4✔
506	if err != nil {	4✔
507	return nil, err	×
508	}	×
509	h.htlcSuccessResolver = successResolver	4✔
510		4✔
511	return h, nil	4✔
512	}
513
514	// Supplement adds additional information to the resolver that is required
515	// before Resolve() is called.
516	//
517	// NOTE: Part of the htlcContractResolver interface.
518	func (h *htlcIncomingContestResolver) Supplement(htlc channeldb.HTLC) {	4✔
519	h.htlc = htlc	4✔
520	}	4✔
521
522	// SupplementDeadline does nothing for an incoming htlc resolver.
523	//
524	// NOTE: Part of the htlcContractResolver interface.
525	func (h *htlcIncomingContestResolver) SupplementDeadline(_ fn.Option[int32]) {	×
526	}	×
527
528	// decodePayload (re)decodes the hop payload of a received htlc.
529	func (h htlcIncomingContestResolver) decodePayload() (hop.Payload,
530	[]byte, error) {	4✔
531		4✔
532	blindingInfo := hop.ReconstructBlindingInfo{	4✔
533	IncomingAmt: h.htlc.Amt,	4✔
534	IncomingExpiry: h.htlc.RefundTimeout,	4✔
535	BlindingKey: h.htlc.BlindingPoint,	4✔
536	}	4✔
537		4✔
538	onionReader := bytes.NewReader(h.htlc.OnionBlob[:])	4✔
539	iterator, err := h.OnionProcessor.ReconstructHopIterator(	4✔
540	onionReader, h.htlc.RHash[:], blindingInfo,	4✔
541	)	4✔
542	if err != nil {	4✔
543	return nil, nil, err	×
544	}	×
545
546	payload, _, err := iterator.HopPayload()	4✔
547	if err != nil {	4✔
548	return nil, nil, err	×
549	}	×
550
551	// Transform onion blob for the next hop.
552	var onionBlob [lnwire.OnionPacketSize]byte	4✔
553	buf := bytes.NewBuffer(onionBlob[0:0])	4✔
554	err = iterator.EncodeNextHop(buf)	4✔
555	if err != nil {	4✔
556	return nil, nil, err	×
557	}	×
558
559	return payload, onionBlob[:], nil	4✔
560	}
561
562	// A compile time assertion to ensure htlcIncomingContestResolver meets the
563	// ContractResolver interface.
564	var _ htlcContractResolver = (*htlcIncomingContestResolver)(nil)

lightningnetwork / lnd / 12199391122

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