9915780197

Committed 13 Jul 2024 12:30AM UTC coverage: 49.268% (-9.1%) from 58.413%

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Merge pull request #8653 from ProofOfKeags/fn-prim

DynComms [0/n]: `fn` package additions

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82.06

/lnwallet/reservation.go

package lnwallet

import (
        "errors"
        "net"
        "sync"

        "github.com/btcsuite/btcd/btcec/v2"
        "github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
        "github.com/btcsuite/btcd/btcutil"
        "github.com/btcsuite/btcd/chaincfg/chainhash"
        "github.com/btcsuite/btcd/wire"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/input"
        "github.com/lightningnetwork/lnd/keychain"
        "github.com/lightningnetwork/lnd/lntypes"
        "github.com/lightningnetwork/lnd/lnwallet/chanfunding"
        "github.com/lightningnetwork/lnd/lnwire"
)

// CommitmentType is an enum indicating the commitment type we should use for
// the channel we are opening.
type CommitmentType int

const (
        // CommitmentTypeLegacy is the legacy commitment format with a tweaked
        // to_remote key.
        CommitmentTypeLegacy = iota

        // CommitmentTypeTweakless is a newer commitment format where the
        // to_remote key is static.
        CommitmentTypeTweakless

        // CommitmentTypeAnchorsZeroFeeHtlcTx is a commitment type that is an
        // extension of the outdated CommitmentTypeAnchors, which in addition
        // requires second-level HTLC transactions to be signed using a
        // zero-fee.
        CommitmentTypeAnchorsZeroFeeHtlcTx

        // CommitmentTypeScriptEnforcedLease is a commitment type that builds
        // upon CommitmentTypeTweakless and CommitmentTypeAnchorsZeroFeeHtlcTx,
        // which in addition requires a CLTV clause to spend outputs paying to
        // the channel initiator. This is intended for use on leased channels to
        // guarantee that the channel initiator has no incentives to close a
        // leased channel before its maturity date.
        CommitmentTypeScriptEnforcedLease

        // CommitmentTypeSimpleTaproot is the base commitment type for the
        // channels that use a musig2 funding output and the tapscript tree
        // where relevant for the commitment transaction pk scripts.
        CommitmentTypeSimpleTaproot
)

// HasStaticRemoteKey returns whether the commitment type supports remote
// outputs backed by static keys.
func (c CommitmentType) HasStaticRemoteKey() bool {
        switch c {
        case CommitmentTypeTweakless,
                CommitmentTypeAnchorsZeroFeeHtlcTx,
                CommitmentTypeScriptEnforcedLease,
                CommitmentTypeSimpleTaproot:
                return true
        default:
                return false
        }
}

// HasAnchors returns whether the commitment type supports anchor outputs.
func (c CommitmentType) HasAnchors() bool {
        switch c {
        case CommitmentTypeAnchorsZeroFeeHtlcTx,
                CommitmentTypeScriptEnforcedLease,
                CommitmentTypeSimpleTaproot:
                return true
        default:
                return false
        }
}

// IsTaproot returns true if the channel type is a taproot channel.
func (c CommitmentType) IsTaproot() bool {
        return c == CommitmentTypeSimpleTaproot
}

// String returns the name of the CommitmentType.
func (c CommitmentType) String() string {
        switch c {
        case CommitmentTypeLegacy:
                return "legacy"
        case CommitmentTypeTweakless:
                return "tweakless"
        case CommitmentTypeAnchorsZeroFeeHtlcTx:
                return "anchors-zero-fee-second-level"
        case CommitmentTypeScriptEnforcedLease:
                return "script-enforced-lease"
        case CommitmentTypeSimpleTaproot:
                return "simple-taproot"
        default:
                return "invalid"
        }
}

// ChannelContribution is the primary constituent of the funding workflow
// within lnwallet. Each side first exchanges their respective contributions
// along with channel specific parameters like the min fee/KB. Once
// contributions have been exchanged, each side will then produce signatures
// for all their inputs to the funding transactions, and finally a signature
// for the other party's version of the commitment transaction.
type ChannelContribution struct {
        // FundingOutpoint is the amount of funds contributed to the funding
        // transaction.
        FundingAmount btcutil.Amount

        // Inputs to the funding transaction.
        Inputs []*wire.TxIn

        // ChangeOutputs are the Outputs to be used in the case that the total
        // value of the funding inputs is greater than the total potential
        // channel capacity.
        ChangeOutputs []*wire.TxOut

        // FirstCommitmentPoint is the first commitment point that will be used
        // to create the revocation key in the first commitment transaction we
        // send to the remote party.
        FirstCommitmentPoint *btcec.PublicKey

        // ChannelConfig is the concrete contribution that this node is
        // offering to the channel. This includes all the various constraints
        // such as the min HTLC, and also all the keys which will be used for
        // the duration of the channel.
        *channeldb.ChannelConfig

        // UpfrontShutdown is an optional address to which the channel should be
        // paid out to on cooperative close.
        UpfrontShutdown lnwire.DeliveryAddress

        // LocalNonce is populated if the channel type is a simple taproot
        // channel. This stores the public (and secret) nonce that will be used
        // to generate commitments for the local party.
        LocalNonce *musig2.Nonces
}

// toChanConfig returns the raw channel configuration generated by a node's
// contribution to the channel.
func (c *ChannelContribution) toChanConfig() channeldb.ChannelConfig {
        return *c.ChannelConfig
}

// ChannelReservation represents an intent to open a lightning payment channel
// with a counterparty. The funding processes from reservation to channel opening
// is a 3-step process. In order to allow for full concurrency during the
// reservation workflow, resources consumed by a contribution are "locked"
// themselves. This prevents a number of race conditions such as two funding
// transactions double-spending the same input. A reservation can also be
// canceled, which removes the resources from limbo, allowing another
// reservation to claim them.
//
// The reservation workflow consists of the following three steps:
//  1. lnwallet.InitChannelReservation
//     * One requests the wallet to allocate the necessary resources for a
//     channel reservation. These resources are put in limbo for the lifetime
//     of a reservation.
//     * Once completed the reservation will have the wallet's contribution
//     accessible via the .OurContribution() method. This contribution
//     contains the necessary items to allow the remote party to build both
//     the funding, and commitment transactions.
//  2. ChannelReservation.ProcessContribution/ChannelReservation.ProcessSingleContribution
//     * The counterparty presents their contribution to the payment channel.
//     This allows us to build the funding, and commitment transactions
//     ourselves.
//     * We're now able to sign our inputs to the funding transactions, and
//     the counterparty's version of the commitment transaction.
//     * All signatures crafted by us, are now available via .OurSignatures().
//  3. ChannelReservation.CompleteReservation/ChannelReservation.CompleteReservationSingle
//     * The final step in the workflow. The counterparty presents the
//     signatures for all their inputs to the funding transaction, as well
//     as a signature to our version of the commitment transaction.
//     * We then verify the validity of all signatures before considering the
//     channel "open".
type ChannelReservation struct {
        // This mutex MUST be held when either reading or modifying any of the
        // fields below.
        sync.RWMutex

        // fundingTx is the funding transaction for this pending channel.
        fundingTx *wire.MsgTx

        // In order of sorted inputs. Sorting is done in accordance
        // to BIP-69: https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki.
        ourFundingInputScripts   []*input.Script
        theirFundingInputScripts []*input.Script

        // Our signature for their version of the commitment transaction.
        ourCommitmentSig   input.Signature
        theirCommitmentSig input.Signature

        ourContribution   *ChannelContribution
        theirContribution *ChannelContribution

        partialState *channeldb.OpenChannel
        nodeAddr     net.Addr

        // The ID of this reservation, used to uniquely track the reservation
        // throughout its lifetime.
        reservationID uint64

        // pendingChanID is the pending channel ID for this channel as
        // identified within the wire protocol.
        pendingChanID [32]byte

        // pushMSat the amount of milli-satoshis that should be pushed to the
        // responder of a single funding channel as part of the initial
        // commitment state.
        pushMSat lnwire.MilliSatoshi

        wallet     *LightningWallet
        chanFunder chanfunding.Assembler

        fundingIntent chanfunding.Intent

        // nextRevocationKeyLoc stores the key locator information for this
        // channel.
        nextRevocationKeyLoc keychain.KeyLocator

        musigSessions *MusigPairSession
}

// NewChannelReservation creates a new channel reservation. This function is
// used only internally by lnwallet. In order to concurrent safety, the
// creation of all channel reservations should be carried out via the
// lnwallet.InitChannelReservation interface.
func NewChannelReservation(capacity, localFundingAmt btcutil.Amount,
        wallet *LightningWallet, id uint64, chainHash *chainhash.Hash,
        thawHeight uint32, req *InitFundingReserveMsg) (*ChannelReservation,
        error) {

        var (
                ourBalance   lnwire.MilliSatoshi
                theirBalance lnwire.MilliSatoshi
                initiator    bool
        )

        // Based on the channel type, we determine the initial commit weight
        // and fee.
        commitWeight := input.CommitWeight
        if req.CommitType.IsTaproot() {
                commitWeight = input.TaprootCommitWeight
        } else if req.CommitType.HasAnchors() {
                commitWeight = input.AnchorCommitWeight
        }
        commitFee := req.CommitFeePerKw.FeeForWeight(
                lntypes.WeightUnit(commitWeight),
        )

        localFundingMSat := lnwire.NewMSatFromSatoshis(localFundingAmt)
        // TODO(halseth): make method take remote funding amount directly
        // instead of inferring it from capacity and local amt.
        capacityMSat := lnwire.NewMSatFromSatoshis(capacity)

        // The total fee paid by the initiator will be the commitment fee in
        // addition to the two anchor outputs.
        feeMSat := lnwire.NewMSatFromSatoshis(commitFee)
        if req.CommitType.HasAnchors() {
                feeMSat += 2 * lnwire.NewMSatFromSatoshis(anchorSize)
        }

        // Used to cut down on verbosity.
        defaultDust := DustLimitUnknownWitness()

        // If we're the responder to a single-funder reservation, then we have
        // no initial balance in the channel unless the remote party is pushing
        // some funds to us within the first commitment state.
        if localFundingAmt == 0 {
                ourBalance = req.PushMSat
                theirBalance = capacityMSat - feeMSat - req.PushMSat
                initiator = false

                // If the responder doesn't have enough funds to actually pay
                // the fees, then we'll bail our early.
                if int64(theirBalance) < 0 {
                        return nil, ErrFunderBalanceDust(
                                int64(commitFee), int64(theirBalance.ToSatoshis()),
                                int64(2*defaultDust),
                        )
                }
        } else {
                // TODO(roasbeef): need to rework fee structure in general and
                // also when we "unlock" dual funder within the daemon

                if capacity == localFundingAmt {
                        // If we're initiating a single funder workflow, then
                        // we pay all the initial fees within the commitment
                        // transaction. We also deduct our balance by the
                        // amount pushed as part of the initial state.
                        ourBalance = capacityMSat - feeMSat - req.PushMSat
                        theirBalance = req.PushMSat
                } else {
                        // Otherwise, this is a dual funder workflow where both
                        // slides split the amount funded and the commitment
                        // fee.
                        ourBalance = localFundingMSat - (feeMSat / 2)
                        theirBalance = capacityMSat - localFundingMSat - (feeMSat / 2) + req.PushMSat
                }

                initiator = true

                // If we, the initiator don't have enough funds to actually pay
                // the fees, then we'll exit with an error.
                if int64(ourBalance) < 0 {
                        return nil, ErrFunderBalanceDust(
                                int64(commitFee), int64(ourBalance),
                                int64(2*defaultDust),
                        )
                }
        }

        // If we're the initiator and our starting balance within the channel
        // after we take account of fees is below 2x the dust limit, then we'll
        // reject this channel creation request.
        //
        // TODO(roasbeef): reject if 30% goes to fees? dust channel
        if initiator && ourBalance.ToSatoshis() <= 2*defaultDust {
                return nil, ErrFunderBalanceDust(
                        int64(commitFee),
                        int64(ourBalance.ToSatoshis()),
                        int64(2*defaultDust),
                )
        }

        // Similarly we ensure their balance is reasonable if we are not the
        // initiator.
        if !initiator && theirBalance.ToSatoshis() <= 2*defaultDust {
                return nil, ErrFunderBalanceDust(
                        int64(commitFee),
                        int64(theirBalance.ToSatoshis()),
                        int64(2*defaultDust),
                )
        }

        // Next we'll set the channel type based on what we can ascertain about
        // the balances/push amount within the channel.
        var chanType channeldb.ChannelType

        // If either of the balances are zero at this point, or we have a
        // non-zero push amt (there's no pushing for dual funder), then this is
        // a single-funder channel.
        if ourBalance == 0 || theirBalance == 0 || req.PushMSat != 0 {
                // Both the tweakless type and the anchor type is tweakless,
                // hence set the bit.
                if req.CommitType.HasStaticRemoteKey() {
                        chanType |= channeldb.SingleFunderTweaklessBit
                } else {
                        chanType |= channeldb.SingleFunderBit
                }

                switch a := req.ChanFunder.(type) {
                // The first channels of a batch shouldn't publish the batch TX
                // to avoid problems if some of the funding flows can't be
                // completed. Only the last channel of a batch should publish.
                case chanfunding.ConditionalPublishAssembler:
                        if !a.ShouldPublishFundingTx() {
                                chanType |= channeldb.NoFundingTxBit
                        }

                // Normal funding flow, the assembler creates a TX from the
                // internal wallet.
                case chanfunding.FundingTxAssembler:
                        // Do nothing, a FundingTxAssembler has the transaction.

                // If this intent isn't one that's able to provide us with a
                // funding transaction, then we'll set the chanType bit to
                // signal that we don't have access to one.
                default:
                        chanType |= channeldb.NoFundingTxBit
                }
        } else {
                // Otherwise, this is a dual funder channel, and no side is
                // technically the "initiator"
                initiator = false
                chanType |= channeldb.DualFunderBit
        }

        // We are adding anchor outputs to our commitment. We only support this
        // in combination with zero-fee second-levels HTLCs.
        if req.CommitType.HasAnchors() {
                chanType |= channeldb.AnchorOutputsBit
                chanType |= channeldb.ZeroHtlcTxFeeBit
        }

        // Set the appropriate LeaseExpiration/Frozen bit based on the
        // reservation parameters.
        if req.CommitType == CommitmentTypeScriptEnforcedLease {
                if thawHeight == 0 {
                        return nil, errors.New("missing absolute expiration " +
                                "for script enforced lease commitment type")
                }
                chanType |= channeldb.LeaseExpirationBit
        } else if thawHeight > 0 {
                chanType |= channeldb.FrozenBit
        }

        if req.CommitType == CommitmentTypeSimpleTaproot {
                chanType |= channeldb.SimpleTaprootFeatureBit
        }

        if req.ZeroConf {
                chanType |= channeldb.ZeroConfBit
        }

        if req.OptionScidAlias {
                chanType |= channeldb.ScidAliasChanBit
        }

        if req.ScidAliasFeature {
                chanType |= channeldb.ScidAliasFeatureBit
        }

        return &ChannelReservation{
                ourContribution: &ChannelContribution{
                        FundingAmount: ourBalance.ToSatoshis(),
                        ChannelConfig: &channeldb.ChannelConfig{},
                },
                theirContribution: &ChannelContribution{
                        FundingAmount: theirBalance.ToSatoshis(),
                        ChannelConfig: &channeldb.ChannelConfig{},
                },
                partialState: &channeldb.OpenChannel{
                        ChanType:     chanType,
                        ChainHash:    *chainHash,
                        IsPending:    true,
                        IsInitiator:  initiator,
                        ChannelFlags: req.Flags,
                        Capacity:     capacity,
                        LocalCommitment: channeldb.ChannelCommitment{
                                LocalBalance:  ourBalance,
                                RemoteBalance: theirBalance,
                                FeePerKw:      btcutil.Amount(req.CommitFeePerKw),
                                CommitFee:     commitFee,
                        },
                        RemoteCommitment: channeldb.ChannelCommitment{
                                LocalBalance:  ourBalance,
                                RemoteBalance: theirBalance,
                                FeePerKw:      btcutil.Amount(req.CommitFeePerKw),
                                CommitFee:     commitFee,
                        },
                        ThawHeight:           thawHeight,
                        Db:                   wallet.Cfg.Database,
                        InitialLocalBalance:  ourBalance,
                        InitialRemoteBalance: theirBalance,
                        Memo:                 req.Memo,
                },
                pushMSat:      req.PushMSat,
                pendingChanID: req.PendingChanID,
                reservationID: id,
                wallet:        wallet,
                chanFunder:    req.ChanFunder,
        }, nil
}

// AddAlias stores the first alias for zero-conf channels.
func (r *ChannelReservation) AddAlias(scid lnwire.ShortChannelID) {
        r.Lock()
        defer r.Unlock()

        r.partialState.ShortChannelID = scid
}

// SetNumConfsRequired sets the number of confirmations that are required for
// the ultimate funding transaction before the channel can be considered open.
// This is distinct from the main reservation workflow as it allows
// implementations a bit more flexibility w.r.t to if the responder of the
// initiator sets decides the number of confirmations needed.
func (r *ChannelReservation) SetNumConfsRequired(numConfs uint16) {
        r.Lock()
        defer r.Unlock()

        r.partialState.NumConfsRequired = numConfs
}

// IsZeroConf returns if the reservation's underlying partial channel state is
// a zero-conf channel.
func (r *ChannelReservation) IsZeroConf() bool {
        r.RLock()
        defer r.RUnlock()

        return r.partialState.IsZeroConf()
}

// IsTaproot returns if the reservation's underlying partial channel state is a
// taproot channel.
func (r *ChannelReservation) IsTaproot() bool {
        r.RLock()
        defer r.RUnlock()

        return r.partialState.ChanType.IsTaproot()
}

// CommitConstraints takes the constraints that the remote party specifies for
// the type of commitments that we can generate for them. These constraints
// include several parameters that serve as flow control restricting the amount
// of satoshis that can be transferred in a single commitment. This function
// will also attempt to verify the constraints for sanity, returning an error
// if the parameters are seemed unsound.
func (r *ChannelReservation) CommitConstraints(c *channeldb.ChannelConstraints,
        maxLocalCSVDelay uint16, responder bool) error {

        r.Lock()
        defer r.Unlock()

        // First, verify the sanity of the channel constraints.
        err := VerifyConstraints(c, maxLocalCSVDelay, r.partialState.Capacity)
        if err != nil {
                return err
        }

        // Our dust limit should always be less than or equal to our proposed
        // channel reserve.
        if responder && r.ourContribution.DustLimit > c.ChanReserve {
                r.ourContribution.DustLimit = c.ChanReserve
        }

        r.ourContribution.ChanReserve = c.ChanReserve
        r.ourContribution.MaxPendingAmount = c.MaxPendingAmount
        r.ourContribution.MinHTLC = c.MinHTLC
        r.ourContribution.MaxAcceptedHtlcs = c.MaxAcceptedHtlcs
        r.ourContribution.CsvDelay = c.CsvDelay

        return nil
}

// validateReserveBounds checks that both ChannelReserve values are above both
// DustLimit values. This not only avoids stuck channels, but is also mandated
// by BOLT#02 even if it's not explicit. This returns true if the bounds are
// valid. This function should be called with the lock held.
func (r *ChannelReservation) validateReserveBounds() bool {
        ourDustLimit := r.ourContribution.DustLimit
        ourRequiredReserve := r.ourContribution.ChanReserve
        theirDustLimit := r.theirContribution.DustLimit
        theirRequiredReserve := r.theirContribution.ChanReserve

        // We take the smaller of the two ChannelReserves and compare it
        // against the larger of the two DustLimits.
        minChanReserve := ourRequiredReserve
        if minChanReserve > theirRequiredReserve {
                minChanReserve = theirRequiredReserve
        }

        maxDustLimit := ourDustLimit
        if maxDustLimit < theirDustLimit {
                maxDustLimit = theirDustLimit
        }

        return minChanReserve >= maxDustLimit
}

// OurContribution returns the wallet's fully populated contribution to the
// pending payment channel. See 'ChannelContribution' for further details
// regarding the contents of a contribution.
//
// NOTE: This SHOULD NOT be modified.
// TODO(roasbeef): make copy?
func (r *ChannelReservation) OurContribution() *ChannelContribution {
        r.RLock()
        defer r.RUnlock()

        return r.ourContribution
}

// ProcessContribution verifies the counterparty's contribution to the pending
// payment channel. As a result of this incoming message, lnwallet is able to
// build the funding transaction, and both commitment transactions. Once this
// message has been processed, all signatures to inputs to the funding
// transaction belonging to the wallet are available. Additionally, the wallet
// will generate a signature to the counterparty's version of the commitment
// transaction.
func (r *ChannelReservation) ProcessContribution(theirContribution *ChannelContribution) error {
        errChan := make(chan error, 1)

        r.wallet.msgChan <- &addContributionMsg{
                pendingFundingID: r.reservationID,
                contribution:     theirContribution,
                err:              errChan,
        }

        return <-errChan
}

// IsPsbt returns true if there is a PSBT funding intent mapped to this
// reservation.
func (r *ChannelReservation) IsPsbt() bool {
        _, ok := r.fundingIntent.(*chanfunding.PsbtIntent)
        return ok
}

// IsCannedShim returns true if there is a canned shim funding intent mapped to
// this reservation.
func (r *ChannelReservation) IsCannedShim() bool {
        _, ok := r.fundingIntent.(*chanfunding.ShimIntent)
        return ok
}

// ProcessPsbt continues a previously paused funding flow that involves PSBT to
// construct the funding transaction. This method can be called once the PSBT is
// finalized and the signed transaction is available.
func (r *ChannelReservation) ProcessPsbt() error {
        errChan := make(chan error, 1)

        r.wallet.msgChan <- &continueContributionMsg{
                pendingFundingID: r.reservationID,
                err:              errChan,
        }

        return <-errChan
}

// RemoteCanceled informs the PSBT funding state machine that the remote peer
// has canceled the pending reservation, likely due to a timeout.
func (r *ChannelReservation) RemoteCanceled() {
        psbtIntent, ok := r.fundingIntent.(*chanfunding.PsbtIntent)
        if !ok {
                return
        }
        psbtIntent.RemoteCanceled()
}

// ProcessSingleContribution verifies, and records the initiator's contribution
// to this pending single funder channel. Internally, no further action is
// taken other than recording the initiator's contribution to the single funder
// channel.
func (r *ChannelReservation) ProcessSingleContribution(theirContribution *ChannelContribution) error {
        errChan := make(chan error, 1)

        r.wallet.msgChan <- &addSingleContributionMsg{
                pendingFundingID: r.reservationID,
                contribution:     theirContribution,
                err:              errChan,
        }

        return <-errChan
}

// TheirContribution returns the counterparty's pending contribution to the
// payment channel. See 'ChannelContribution' for further details regarding the
// contents of a contribution. This attribute will ONLY be available after a
// call to .ProcessContribution().
//
// NOTE: This SHOULD NOT be modified.
func (r *ChannelReservation) TheirContribution() *ChannelContribution {
        r.RLock()
        defer r.RUnlock()
        return r.theirContribution
}

// OurSignatures retrieves the wallet's signatures to all inputs to the funding
// transaction belonging to itself, and also a signature for the counterparty's
// version of the commitment transaction. The signatures for the wallet's
// inputs to the funding transaction are returned in sorted order according to
// BIP-69: https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki.
//
// NOTE: These signatures will only be populated after a call to
// .ProcessContribution()
func (r *ChannelReservation) OurSignatures() ([]*input.Script,
        input.Signature) {

        r.RLock()
        defer r.RUnlock()
        return r.ourFundingInputScripts, r.ourCommitmentSig
}

// CompleteReservation finalizes the pending channel reservation, transitioning
// from a pending payment channel, to an open payment channel. All passed
// signatures to the counterparty's inputs to the funding transaction will be
// fully verified. Signatures are expected to be passed in sorted order
// according to BIP-69:
// https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki.
// Additionally, verification is performed in order to ensure that the
// counterparty supplied a valid signature to our version of the commitment
// transaction.  Once this method returns, callers should broadcast the
// created funding transaction, then call .WaitForChannelOpen() which will
// block until the funding transaction obtains the configured number of
// confirmations. Once the method unblocks, a LightningChannel instance is
// returned, marking the channel available for updates.
func (r *ChannelReservation) CompleteReservation(fundingInputScripts []*input.Script,
        commitmentSig input.Signature) (*channeldb.OpenChannel, error) {

        // TODO(roasbeef): add flag for watch or not?
        errChan := make(chan error, 1)
        completeChan := make(chan *channeldb.OpenChannel, 1)

        r.wallet.msgChan <- &addCounterPartySigsMsg{
                pendingFundingID:         r.reservationID,
                theirFundingInputScripts: fundingInputScripts,
                theirCommitmentSig:       commitmentSig,
                completeChan:             completeChan,
                err:                      errChan,
        }

        return <-completeChan, <-errChan
}

// CompleteReservationSingle finalizes the pending single funder channel
// reservation. Using the funding outpoint of the constructed funding
// transaction, and the initiator's signature for our version of the commitment
// transaction, we are able to verify the correctness of our commitment
// transaction as crafted by the initiator. Once this method returns, our
// signature for the initiator's version of the commitment transaction is
// available via the .OurSignatures() method. As this method should only be
// called as a response to a single funder channel, only a commitment signature
// will be populated.
func (r *ChannelReservation) CompleteReservationSingle(fundingPoint *wire.OutPoint,
        commitSig input.Signature) (*channeldb.OpenChannel, error) {

        errChan := make(chan error, 1)
        completeChan := make(chan *channeldb.OpenChannel, 1)

        r.wallet.msgChan <- &addSingleFunderSigsMsg{
                pendingFundingID:   r.reservationID,
                fundingOutpoint:    fundingPoint,
                theirCommitmentSig: commitSig,
                completeChan:       completeChan,
                err:                errChan,
        }

        return <-completeChan, <-errChan
}

// TheirSignatures returns the counterparty's signatures to all inputs to the
// funding transaction belonging to them, as well as their signature for the
// wallet's version of the commitment transaction. This methods is provided for
// additional verification, such as needed by tests.
//
// NOTE: These attributes will be unpopulated before a call to
// .CompleteReservation().
func (r *ChannelReservation) TheirSignatures() ([]*input.Script,
        input.Signature) {

        r.RLock()
        defer r.RUnlock()
        return r.theirFundingInputScripts, r.theirCommitmentSig
}

// FinalFundingTx returns the finalized, fully signed funding transaction for
// this reservation.
//
// NOTE: If this reservation was created as the non-initiator to a single
// funding workflow, then the full funding transaction will not be available.
// Instead we will only have the final outpoint of the funding transaction.
func (r *ChannelReservation) FinalFundingTx() *wire.MsgTx {
        r.RLock()
        defer r.RUnlock()
        return r.fundingTx
}

// FundingOutpoint returns the outpoint of the funding transaction.
//
// NOTE: The pointer returned will only be set once the .ProcessContribution()
// method is called in the case of the initiator of a single funder workflow,
// and after the .CompleteReservationSingle() method is called in the case of
// a responder to a single funder workflow.
func (r *ChannelReservation) FundingOutpoint() *wire.OutPoint {
        r.RLock()
        defer r.RUnlock()
        return &r.partialState.FundingOutpoint
}

// SetOurUpfrontShutdown sets the upfront shutdown address on our contribution.
func (r *ChannelReservation) SetOurUpfrontShutdown(shutdown lnwire.DeliveryAddress) {
        r.Lock()
        defer r.Unlock()

        r.ourContribution.UpfrontShutdown = shutdown
}

// Capacity returns the channel capacity for this reservation.
func (r *ChannelReservation) Capacity() btcutil.Amount {
        r.RLock()
        defer r.RUnlock()
        return r.partialState.Capacity
}

// LeaseExpiry returns the absolute expiration height for a leased channel using
// the script enforced commitment type. A zero value is returned when the
// channel is not using a script enforced lease commitment type.
func (r *ChannelReservation) LeaseExpiry() uint32 {
        if !r.partialState.ChanType.HasLeaseExpiration() {
                return 0
        }
        return r.partialState.ThawHeight
}

// Cancel abandons this channel reservation. This method should be called in
// the scenario that communications with the counterparty break down. Upon
// cancellation, all resources previously reserved for this pending payment
// channel are returned to the free pool, allowing subsequent reservations to
// utilize the now freed resources.
func (r *ChannelReservation) Cancel() error {
        errChan := make(chan error, 1)
        r.wallet.msgChan <- &fundingReserveCancelMsg{
                pendingFundingID: r.reservationID,
                err:              errChan,
        }

        return <-errChan
}

// VerifyConstraints is a helper function that can be used to check the sanity
// of various channel constraints.
func VerifyConstraints(c *channeldb.ChannelConstraints,
        maxLocalCSVDelay uint16, channelCapacity btcutil.Amount) error {

        // Fail if the csv delay for our funds exceeds our maximum.
        if c.CsvDelay > maxLocalCSVDelay {
                return ErrCsvDelayTooLarge(c.CsvDelay, maxLocalCSVDelay)
        }

        // The channel reserve should always be greater or equal to the dust
        // limit. The reservation request should be denied if otherwise.
        if c.DustLimit > c.ChanReserve {
                return ErrChanReserveTooSmall(c.ChanReserve, c.DustLimit)
        }

        // Validate against the maximum-sized witness script dust limit, and
        // also ensure that the DustLimit is not too large.
        maxWitnessLimit := DustLimitForSize(input.UnknownWitnessSize)
        if c.DustLimit < maxWitnessLimit || c.DustLimit > 3*maxWitnessLimit {
                return ErrInvalidDustLimit(c.DustLimit)
        }

        // Fail if we consider the channel reserve to be too large.  We
        // currently fail if it is greater than 20% of the channel capacity.
        maxChanReserve := channelCapacity / 5
        if c.ChanReserve > maxChanReserve {
                return ErrChanReserveTooLarge(c.ChanReserve, maxChanReserve)
        }

        // Fail if the minimum HTLC value is too large. If this is too large,
        // the channel won't be useful for sending small payments. This limit
        // is currently set to maxValueInFlight, effectively letting the remote
        // setting this as large as it wants.
        if c.MinHTLC > c.MaxPendingAmount {
                return ErrMinHtlcTooLarge(c.MinHTLC, c.MaxPendingAmount)
        }

        // Fail if maxHtlcs is above the maximum allowed number of 483.  This
        // number is specified in BOLT-02.
        if c.MaxAcceptedHtlcs > uint16(input.MaxHTLCNumber/2) {
                return ErrMaxHtlcNumTooLarge(
                        c.MaxAcceptedHtlcs, uint16(input.MaxHTLCNumber/2),
                )
        }

        // Fail if we consider maxHtlcs too small. If this is too small we
        // cannot offer many HTLCs to the remote.
        const minNumHtlc = 5
        if c.MaxAcceptedHtlcs < minNumHtlc {
                return ErrMaxHtlcNumTooSmall(c.MaxAcceptedHtlcs, minNumHtlc)
        }

        // Fail if we consider maxValueInFlight too small. We currently require
        // the remote to at least allow minNumHtlc * minHtlc in flight.
        if c.MaxPendingAmount < minNumHtlc*c.MinHTLC {
                return ErrMaxValueInFlightTooSmall(
                        c.MaxPendingAmount, minNumHtlc*c.MinHTLC,
                )
        }

        return nil
}

// OpenChannelDetails wraps the finalized fully confirmed channel which
// resulted from a ChannelReservation instance with details concerning exactly
// _where_ in the chain the channel was ultimately opened.
type OpenChannelDetails struct {
        // Channel is the active channel created by an instance of a
        // ChannelReservation and the required funding workflow.
        Channel *LightningChannel

        // ConfirmationHeight is the block height within the chain that
        // included the channel.
        ConfirmationHeight uint32

        // TransactionIndex is the index within the confirming block that the
        // transaction resides.
        TransactionIndex uint32
}

lightningnetwork / lnd / 9915780197

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