13558005087

Committed 27 Feb 2025 03:04AM UTC coverage: 58.834% (-0.001%) from 58.835%

Build # 13558005087

Build Type

Pull #8453

github

Committed by

Roasbeef

Commit Message

lnwallet/chancloser: increase test coverage of state machine

Pull Request Pull Request #8453: [4/4] - multi: integrate new rbf coop close FSM into the existing peer flow

Run Details

1079 of 1370 new or added lines in 23 files covered. (78.76%)

578 existing lines in 40 files now uncovered.

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Source File
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67.53

/lnwallet/chancloser/rbf_coop_states.go

package chancloser

import (
        "fmt"

        "github.com/btcsuite/btcd/btcec/v2"
        "github.com/btcsuite/btcd/btcutil"
        "github.com/btcsuite/btcd/chaincfg"
        "github.com/btcsuite/btcd/wire"
        "github.com/lightningnetwork/lnd/chainntnfs"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/fn/v2"
        "github.com/lightningnetwork/lnd/input"
        "github.com/lightningnetwork/lnd/lntypes"
        "github.com/lightningnetwork/lnd/lnwallet"
        "github.com/lightningnetwork/lnd/lnwallet/chainfee"
        "github.com/lightningnetwork/lnd/lnwire"
        "github.com/lightningnetwork/lnd/protofsm"
)

var (
        // ErrInvalidStateTransition is returned when we receive an unexpected
        // event for a given state.
        ErrInvalidStateTransition = fmt.Errorf("invalid state transition")

        // ErrTooManySigs is returned when we receive too many sigs from the
        // remote party in the ClosingSigs message.
        ErrTooManySigs = fmt.Errorf("too many sigs received")

        // ErrNoSig is returned when we receive no sig from the remote party.
        ErrNoSig = fmt.Errorf("no sig received")

        // ErrUnknownFinalBalance is returned if we're unable to determine the
        // final channel balance after a flush.
        ErrUnknownFinalBalance = fmt.Errorf("unknown final balance")

        // ErrRemoteCannotPay is returned if the remote party cannot pay the
        // pay for the fees when it sends a signature.
        ErrRemoteCannotPay = fmt.Errorf("remote cannot pay fees")

        // ErrNonFinalSequence is returned if we receive a non-final sequence
        // from the remote party for their signature.
        ErrNonFinalSequence = fmt.Errorf("received non-final sequence")

        // ErrCloserNoClosee is returned if our balance is dust, but the remote
        // party includes our output.
        ErrCloserNoClosee = fmt.Errorf("expected CloserNoClosee sig")

        // ErrCloserAndClosee is returned when we expect a sig covering both
        // outputs, it isn't present.
        ErrCloserAndClosee = fmt.Errorf("expected CloserAndClosee sig")

        // ErrWrongLocalScript is returned when the remote party sends a
        // ClosingComplete message that doesn't carry our last local script
        // sent.
        ErrWrongLocalScript = fmt.Errorf("wrong local script")
)

// ProtocolEvent is a special interface used to create the equivalent of a
// sum-type, but using a "sealed" interface. Protocol events can be used as
// input to trigger a state transition, and also as output to trigger a new set
// of events into the very same state machine.
type ProtocolEvent interface {
        protocolSealed()
}

// ProtocolEvents is a special type constraint that enumerates all the possible
// protocol events. This is used mainly as type-level documentation, and may
// also be useful to constraint certain state transition functions.
type ProtocolEvents interface {
        SendShutdown | ShutdownReceived | ShutdownComplete | ChannelFlushed |
                SendOfferEvent | OfferReceivedEvent | LocalSigReceived |
                SpendEvent
}

// SpendEvent indicates that a transaction spending the funding outpoint has
// been confirmed in the main chain.
type SpendEvent struct {
        // Tx is the spending transaction that has been confirmed.
        Tx *wire.MsgTx

        // BlockHeight is the height of the block that confirmed the
        // transaction.
        BlockHeight uint32
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (s *SpendEvent) protocolSealed() {}

// SendShutdown indicates that the user wishes to co-op close the channel, so we
// should send a new shutdown message to the remote party.
//
// transition:
//   - fromState: ChannelActive
//   - toState: ChannelFlushing
type SendShutdown struct {
        // DeliveryAddr is the address we'd like to receive the funds to. If
        // None, then a new addr will be generated.
        DeliveryAddr fn.Option[lnwire.DeliveryAddress]

        // IdealFeeRate is the ideal fee rate we'd like to use for the closing
        // attempt.
        IdealFeeRate chainfee.SatPerVByte
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (s *SendShutdown) protocolSealed() {}

// ShutdownReceived indicates that we received a shutdown event so we need to
// enter the flushing state.
//
// transition:
//   - fromState: ChannelActive
//   - toState: ChannelFlushing
type ShutdownReceived struct {
        // ShutdownScript is the script the remote party wants to use to
        // shutdown.
        ShutdownScript lnwire.DeliveryAddress

        // BlockHeight is the height at which the shutdown message was
        // received. This is used for channel leases to determine if a co-op
        // close can occur.
        BlockHeight uint32
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (s *ShutdownReceived) protocolSealed() {}

// ShutdownComplete is an event that indicates the channel has been fully
// shutdown. At this point, we'll go to the ChannelFlushing state so we can
// wait for all pending updates to be gone from the channel.
//
// transition:
//   - fromState: ShutdownPending
//   - toState: ChannelFlushing
type ShutdownComplete struct {
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (s *ShutdownComplete) protocolSealed() {}

// ShutdownBalances holds the local+remote balance once the channel has been
// fully flushed.
type ShutdownBalances struct {
        // LocalBalance is the local balance of the channel.
        LocalBalance lnwire.MilliSatoshi

        // RemoteBalance is the remote balance of the channel.
        RemoteBalance lnwire.MilliSatoshi
}

// unknownBalance is a special variable used to denote an unknown channel
// balance (channel not fully flushed yet).
var unknownBalance = ShutdownBalances{}

// ChannelFlushed is an event that indicates the channel has been fully flushed
// can we can now start closing negotiation.
//
// transition:
//   - fromState: ChannelFlushing
//   - toState: ClosingNegotiation
type ChannelFlushed struct {
        // FreshFlush indicates if this is the first time the channel has been
        // flushed, or if this is a flush as part of an RBF iteration.
        FreshFlush bool

        // ShutdownBalances is the balances of the channel once it has been
        // flushed. We tie this to the ChannelFlushed state as this may not be
        // the same as the starting value.
        ShutdownBalances
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (c *ChannelFlushed) protocolSealed() {}

// SendOfferEvent is a self-triggered event that transitions us from the
// LocalCloseStart state to the LocalOfferSent state. This kicks off the new
// signing process for the co-op close process.
//
// transition:
//   - fromState: LocalCloseStart
//   - toState: LocalOfferSent
type SendOfferEvent struct {
        // TargetFeeRate is the fee rate we'll use for the closing transaction.
        TargetFeeRate chainfee.SatPerVByte
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (s *SendOfferEvent) protocolSealed() {}

// LocalSigReceived is an event that indicates we've received a signature from
// the remote party, which signs our the co-op close transaction at our
// specified fee rate.
//
// transition:
//   - fromState: LocalOfferSent
//   - toState: ClosePending
type LocalSigReceived struct {
        // SigMsg is the sig message we received from the remote party.
        SigMsg lnwire.ClosingSig
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (s *LocalSigReceived) protocolSealed() {}

// OfferReceivedEvent is an event that indicates we've received an offer from
// the remote party. This applies to the RemoteCloseStart state.
//
// transition:
//   - fromState: RemoteCloseStart
//   - toState: ClosePending
type OfferReceivedEvent struct {
        // SigMsg is the signature message we received from the remote party.
        SigMsg lnwire.ClosingComplete
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (s *OfferReceivedEvent) protocolSealed() {}

// CloseSigner is an interface that abstracts away the details of the signing
// new coop close transactions.
type CloseSigner interface {
        // CreateCloseProposal creates a new co-op close proposal in the form
        // of a valid signature, the chainhash of the final txid, and our final
        // balance in the created state.
        CreateCloseProposal(proposedFee btcutil.Amount,
                localDeliveryScript []byte, remoteDeliveryScript []byte,
                closeOpt ...lnwallet.ChanCloseOpt,
        ) (
                input.Signature, *wire.MsgTx, btcutil.Amount, error)

        // CompleteCooperativeClose persistently "completes" the cooperative
        // close by producing a fully signed co-op close transaction.
        CompleteCooperativeClose(localSig, remoteSig input.Signature,
                localDeliveryScript, remoteDeliveryScript []byte,
                proposedFee btcutil.Amount, closeOpt ...lnwallet.ChanCloseOpt,
        ) (*wire.MsgTx, btcutil.Amount, error)
}

// ChanStateObserver is an interface used to observe state changes that occur
// in a channel. This can be used to figure out if we're able to send a
// shutdown message or not.
type ChanStateObserver interface {
        // NoDanglingUpdates returns true if there are no dangling updates in
        // the channel. In other words, there are no active update messages
        // that haven't already been covered by a commit sig.
        NoDanglingUpdates() bool

        // DisableIncomingAdds instructs the channel link to disable process new
        // incoming add messages.
        DisableIncomingAdds() error

        // DisableOutgoingAdds instructs the channel link to disable process
        // new outgoing add messages.
        DisableOutgoingAdds() error

        // DisableChannel attempts to disable a channel (marking it ineligible
        // to forward), and also sends out a network update to disable the
        // channel.
        DisableChannel() error

        // MarkCoopBroadcasted persistently marks that the channel close
        // transaction has been broadcast.
        MarkCoopBroadcasted(*wire.MsgTx, bool) error

        // MarkShutdownSent persists the given ShutdownInfo. The existence of
        // the ShutdownInfo represents the fact that the Shutdown message has
        // been sent by us and so should be re-sent on re-establish.
        MarkShutdownSent(deliveryAddr []byte, isInitiator bool) error

        // FinalBalances is the balances of the channel once it has been
        // flushed. If Some, then this indicates that the channel is now in a
        // state where it's always flushed, so we can accelerate the state
        // transitions.
        FinalBalances() fn.Option[ShutdownBalances]
}

// Environment is a set of dependencies that a state machine may need to carry
// out the logic for a given state transition. All fields are to be considered
// immutable, and will be fixed for the lifetime of the state machine.
type Environment struct {
        // ChainParams is the chain parameters for the channel.
        ChainParams chaincfg.Params

        // ChanPeer is the peer we're attempting to close the channel with.
        ChanPeer btcec.PublicKey

        // ChanPoint is the channel point of the active channel.
        ChanPoint wire.OutPoint

        // ChanID is the channel ID of the channel we're attempting to close.
        ChanID lnwire.ChannelID

        // ShortChanID is the short channel ID of the channel we're attempting
        // to close.
        Scid lnwire.ShortChannelID

        // ChanType is the type of channel we're attempting to close.
        ChanType channeldb.ChannelType

        // BlockHeight is the current block height.
        BlockHeight uint32

        // DefaultFeeRate is the fee we'll use for the closing transaction if
        // the user didn't specify an ideal fee rate. This may happen if the
        // remote party is the one that initiates the co-op close.
        DefaultFeeRate chainfee.SatPerVByte

        // ThawHeight is the height at which the channel will be thawed. If
        // this is None, then co-op close can occur at any moment.
        ThawHeight fn.Option[uint32]

        // RemoteUprontShutdown is the upfront shutdown addr of the remote
        // party. We'll use this to validate if the remote peer is authorized to
        // close the channel with the sent addr or not.
        RemoteUpfrontShutdown fn.Option[lnwire.DeliveryAddress]

        // LocalUprontShutdown is our upfront shutdown address. If Some, then
        // we'll default to using this.
        LocalUpfrontShutdown fn.Option[lnwire.DeliveryAddress]

        // NewDeliveryScript is a function that returns a new delivery script.
        // This is used if we don't have an upfront shutdown addr, and no addr
        // was specified at closing time.
        NewDeliveryScript func() (lnwire.DeliveryAddress, error)

        // FeeEstimator is the fee estimator we'll use to determine the fee in
        // satoshis we'll pay given a local and/or remote output.
        FeeEstimator CoopFeeEstimator

        // ChanObserver is an interface used to observe state changes to the
        // channel. We'll use this to figure out when/if we can send certain
        // messages.
        ChanObserver ChanStateObserver

        // CloseSigner is the signer we'll use to sign the close transaction.
        // This is a part of the ChannelFlushed state, as the channel state
        // we'll be signing can only be determined once the channel has been
        // flushed.
        CloseSigner CloseSigner
}

// Name returns the name of the environment. This is used to uniquely identify
// the environment of related state machines. For this state machine, the name
// is based on the channel ID.
func (e *Environment) Name() string {
        return fmt.Sprintf("rbf_chan_closer(%v)", e.ChanPoint)
}

// CloseStateTransition is the StateTransition type specific to the coop close
// state machine.
//
//nolint:ll
type CloseStateTransition = protofsm.StateTransition[ProtocolEvent, *Environment]

// ProtocolState is our sum-type ish interface that represents the current
// protocol state.
type ProtocolState interface {
        // protocolStateSealed is a special method that is used to seal the
        // interface (only types in this package can implement it).
        protocolStateSealed()

        // IsTerminal returns true if the target state is a terminal state.
        IsTerminal() bool

        // ProcessEvent takes a protocol event, and implements a state
        // transition for the state.
        ProcessEvent(ProtocolEvent, *Environment) (*CloseStateTransition, error)

        // String returns the name of the state.
        String() string
}

// AsymmetricPeerState is an extension of the normal ProtocolState interface
// that gives a caller a hit on if the target state should process an incoming
// event or not.
type AsymmetricPeerState interface {
        ProtocolState

        // ShouldRouteTo returns true if the target state should process the
        // target event.
        ShouldRouteTo(ProtocolEvent) bool
}

// ProtocolStates is a special type constraint that enumerates all the possible
// protocol states.
type ProtocolStates interface {
        ChannelActive | ShutdownPending | ChannelFlushing | ClosingNegotiation |
                LocalCloseStart | LocalOfferSent | RemoteCloseStart |
                ClosePending | CloseFin | CloseErr
}

// ChannelActive is the base state for the channel closer state machine. In
// this state, we haven't begun the shutdown process yet, so the channel is
// still active. Receiving the ShutdownSent or ShutdownReceived events will
// transition us to the ChannelFushing state.
//
// When we transition to this state, we emit a DaemonEvent to send the shutdown
// message if we received one ourselves. Alternatively, we may send out a new
// shutdown if we're initiating it for the very first time.
//
// transition:
//   - fromState: None
//   - toState: ChannelFlushing
//
// input events:
//   - SendShutdown
//   - ShutdownReceived
type ChannelActive struct {
}

// String returns the name of the state for ChannelActive.
func (c *ChannelActive) String() string {
        return "ChannelActive"
}

// IsTerminal returns true if the target state is a terminal state.
func (c *ChannelActive) IsTerminal() bool {
        return false
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (c *ChannelActive) protocolStateSealed() {}

// ShutdownScripts is a set of scripts that we'll use to co-op close the
// channel.
type ShutdownScripts struct {
        // LocalDeliveryScript is the script that we'll send our settled
        // channel funds to.
        LocalDeliveryScript lnwire.DeliveryAddress

        // RemoteDeliveryScript is the script that we'll send the remote
        // party's settled channel funds to.
        RemoteDeliveryScript lnwire.DeliveryAddress
}

// ShutdownPending is the state we enter into after we've sent or received the
// shutdown message. If we sent the shutdown, then we'll wait for the remote
// party to send a shutdown. Otherwise, if we received it, then we'll send our
// shutdown then go to the next state.
//
// transition:
//   - fromState: ChannelActive
//   - toState: ChannelFlushing
//
// input events:
//   - SendShutdown
//   - ShutdownReceived
type ShutdownPending struct {
        // ShutdownScripts store the set of scripts we'll use to initiate a coop
        // close.
        ShutdownScripts

        // IdealFeeRate is the ideal fee rate we'd like to use for the closing
        // attempt.
        IdealFeeRate fn.Option[chainfee.SatPerVByte]

        // EarlyRemoteOffer is the offer we received from the remote party
        // before we received their shutdown message. We'll stash it to process
        // later.
        EarlyRemoteOffer fn.Option[OfferReceivedEvent]
}

// String returns the name of the state for ShutdownPending.
func (s *ShutdownPending) String() string {
        return "ShutdownPending"
}

// IsTerminal returns true if the target state is a terminal state.
func (s *ShutdownPending) IsTerminal() bool {
        return false
}

// protocolStateSealed indicates that this struct is a ProtocolEvent instance.
func (s *ShutdownPending) protocolStateSealed() {}

// ChannelFlushing is the state we enter into after we've received or sent a
// shutdown message. In this state, we wait the ChannelFlushed event, after
// which we'll transition to the CloseReady state.
//
// transition:
//   - fromState: ShutdownPending
//   - toState: ClosingNegotiation
//
// input events:
//   - ShutdownComplete
//   - ShutdownReceived
type ChannelFlushing struct {
        // EarlyRemoteOffer is the offer we received from the remote party
        // before we obtained the local channel flushed event. We'll stash this
        // to process later.
        EarlyRemoteOffer fn.Option[OfferReceivedEvent]

        // ShutdownScripts store the set of scripts we'll use to initiate a coop
        // close.
        ShutdownScripts

        // IdealFeeRate is the ideal fee rate we'd like to use for the closing
        // transaction. Once the channel has been flushed, we'll use this as
        // our target fee rate.
        IdealFeeRate fn.Option[chainfee.SatPerVByte]
}

// String returns the name of the state for ChannelFlushing.
func (c *ChannelFlushing) String() string {
        return "ChannelFlushing"
}

// protocolStateSealed indicates that this struct is a ProtocolEvent instance.
func (c *ChannelFlushing) protocolStateSealed() {}

// IsTerminal returns true if the target state is a terminal state.
func (c *ChannelFlushing) IsTerminal() bool {
        return false
}

// ClosingNegotiation is the state we transition to once the channel has been
// flushed. This is actually a composite state that contains one for each side
// of the channel, as the closing process is asymmetric. Once either of the
// peer states reaches the CloseFin state, then the channel is fully closed,
// and we'll transition to that terminal state.
//
// transition:
//   - fromState: ChannelFlushing
//   - toState: CloseFin
//
// input events:
//   - ChannelFlushed
type ClosingNegotiation struct {
        // PeerStates is a composite state that contains the state for both the
        // local and remote parties. Our usage of Dual makes this a special
        // state that allows us to treat two states as a single state. We'll use
        // the ShouldRouteTo method to determine which state route incoming
        // events to.
        PeerState lntypes.Dual[AsymmetricPeerState]

        // CloseChannelTerms is the terms we'll use to close the channel. We
        // hold a value here which is pointed to by the various
        // AsymmetricPeerState instances. This allows us to update this value if
        // the remote peer sends a new address, with each of the state noting
        // the new value via a pointer.
        *CloseChannelTerms
}

// String returns the name of the state for ClosingNegotiation.
func (c *ClosingNegotiation) String() string {
        localState := c.PeerState.GetForParty(lntypes.Local)
        remoteState := c.PeerState.GetForParty(lntypes.Remote)

        return fmt.Sprintf("ClosingNegotiation(local=%v, remote=%v)",
                localState, remoteState)
}

// IsTerminal returns true if the target state is a terminal state.
func (c *ClosingNegotiation) IsTerminal() bool {
        return false
}

// protocolSealed indicates that this struct is a ProtocolEvent instance.
func (c *ClosingNegotiation) protocolStateSealed() {}

// ErrState can be used to introspect into a benign error related to a state
// transition.
type ErrState interface {
        sealed()

        error

        // Err returns an error for the ErrState.
        Err() error
}

// ErrStateCantPayForFee is sent when the local party attempts a fee update
// that they can't actually party for.
type ErrStateCantPayForFee struct {
        localBalance btcutil.Amount

        attemptedFee btcutil.Amount
}

// NewErrStateCantPayForFee returns a new NewErrStateCantPayForFee error.
func NewErrStateCantPayForFee(localBalance, attemptedFee btcutil.Amount,
) *ErrStateCantPayForFee {

        return &ErrStateCantPayForFee{
                localBalance: localBalance,
                attemptedFee: attemptedFee,
        }
}

// sealed makes this a sealed interface.
func (e *ErrStateCantPayForFee) sealed() {
}

// Err returns an error for the ErrState.
func (e *ErrStateCantPayForFee) Err() error {
        return fmt.Errorf("cannot pay for fee of %v, only have %v local "+
                "balance", e.attemptedFee, e.localBalance)
}

// Error returns the error string for the ErrState.
func (e *ErrStateCantPayForFee) Error() string {
        return e.Err().Error()
}

// CloseChannelTerms is a set of terms that we'll use to close the channel. This
// includes the balances of the channel, and the scripts we'll use to send each
// party's funds to.
type CloseChannelTerms struct {
        ShutdownScripts

        ShutdownBalances
}

// DeriveCloseTxOuts takes the close terms, and returns the local and remote tx
// out for the close transaction. If an output is dust, then it'll be nil.
func (c *CloseChannelTerms) DeriveCloseTxOuts() (*wire.TxOut, *wire.TxOut) {
        //nolint:ll
        deriveTxOut := func(balance btcutil.Amount, pkScript []byte) *wire.TxOut {
                // We'll base the existence of the output on our normal dust
                // check.
                dustLimit := lnwallet.DustLimitForSize(len(pkScript))
                if balance >= dustLimit {
                        return &wire.TxOut{
                                PkScript: pkScript,
                                Value:    int64(balance),
                        }
                }

                return nil
        }

        localTxOut := deriveTxOut(
                c.LocalBalance.ToSatoshis(),
                c.LocalDeliveryScript,
        )
        remoteTxOut := deriveTxOut(
                c.RemoteBalance.ToSatoshis(),
                c.RemoteDeliveryScript,
        )

        return localTxOut, remoteTxOut
}

// RemoteAmtIsDust returns true if the remote output is dust.
func (c *CloseChannelTerms) RemoteAmtIsDust() bool {
        return c.RemoteBalance.ToSatoshis() < lnwallet.DustLimitForSize(
                len(c.RemoteDeliveryScript),
        )
}

// LocalAmtIsDust returns true if the local output is dust.
func (c *CloseChannelTerms) LocalAmtIsDust() bool {
        return c.LocalBalance.ToSatoshis() < lnwallet.DustLimitForSize(
                len(c.LocalDeliveryScript),
        )
}

// LocalCanPayFees returns true if the local party can pay the absolute fee
// from their local settled balance.
func (c *CloseChannelTerms) LocalCanPayFees(absoluteFee btcutil.Amount) bool {
        return c.LocalBalance.ToSatoshis() >= absoluteFee
}

// RemoteCanPayFees returns true if the remote party can pay the absolute fee
// from their remote settled balance.
func (c *CloseChannelTerms) RemoteCanPayFees(absoluteFee btcutil.Amount) bool {
        return c.RemoteBalance.ToSatoshis() >= absoluteFee
}

// LocalCloseStart is the state we enter into after we've received or sent
// shutdown, and the channel has been flushed. In this state, we'll emit a new
// event to send our offer to drive the rest of the process.
//
// transition:
//   - fromState: ChannelFlushing
//   - toState: LocalOfferSent
//
// input events:
//   - SendOfferEvent
type LocalCloseStart struct {
        *CloseChannelTerms
}

// String returns the name of the state for LocalCloseStart, including proposed
// fee details.
func (l *LocalCloseStart) String() string {
        return "LocalCloseStart"
}

// ShouldRouteTo returns true if the target state should process the target
// event.
func (l *LocalCloseStart) ShouldRouteTo(event ProtocolEvent) bool {
        switch event.(type) {
        case *SendOfferEvent:
                return true
        default:
                return false
        }
}

// IsTerminal returns true if the target state is a terminal state.
func (l *LocalCloseStart) IsTerminal() bool {
        return false
}

// protocolStateaSealed indicates that this struct is a ProtocolEvent instance.
func (l *LocalCloseStart) protocolStateSealed() {}

// LocalOfferSent is the state we transition to after we reveiver the
// SendOfferEvent in the LocalCloseStart state. With this state we send our
// offer to the remote party, then await a sig from them which concludes the
// local cooperative close process.
//
// transition:
//   - fromState: LocalCloseStart
//   - toState: ClosePending
//
// input events:
//   - LocalSigReceived
type LocalOfferSent struct {
        *CloseChannelTerms

        // ProposedFee is the fee we proposed to the remote party.
        ProposedFee btcutil.Amount

        // ProposedFeeRate is the fee rate we proposed to the remote party.
        ProposedFeeRate chainfee.SatPerVByte

        // LocalSig is the signature we sent to the remote party.
        LocalSig lnwire.Sig
}

// String returns the name of the state for LocalOfferSent, including proposed

func (l *LocalOfferSent) String() string {
        return fmt.Sprintf("LocalOfferSent(proposed_fee=%v, "+
                "proposed_fee_rate=%v)", l.ProposedFee, l.ProposedFee)
}

// ShouldRouteTo returns true if the target state should process the target
// event.
func (l *LocalOfferSent) ShouldRouteTo(event ProtocolEvent) bool {
        switch event.(type) {
        case *LocalSigReceived:
                return true
        default:
                return false
        }
}

// protocolStateaSealed indicates that this struct is a ProtocolEvent instance.
func (l *LocalOfferSent) protocolStateSealed() {}

// IsTerminal returns true if the target state is a terminal state.
func (l *LocalOfferSent) IsTerminal() bool {
        return false
}

// ClosePending is the state we enter after concluding the negotiation for the
// remote or local state. At this point, given a confirmation notification we
// can terminate the process. Otherwise, we can receive a fresh CoopCloseReq to
// go back to the very start.
//
// transition:
//   - fromState: LocalOfferSent || RemoteCloseStart
//   - toState: CloseFin
//
// input events:
//   - LocalSigReceived
//   - OfferReceivedEvent
type ClosePending struct {
        // CloseTx is the pending close transaction.
        CloseTx *wire.MsgTx

        *CloseChannelTerms

        // FeeRate is the fee rate of the closing transaction.
        FeeRate chainfee.SatPerVByte

        // Party indicates which party is at this state. This is used to
        // implement the state transition properly, based on ShouldRouteTo.
        Party lntypes.ChannelParty
}

// String returns the name of the state for ClosePending.
func (c *ClosePending) String() string {
        return fmt.Sprintf("ClosePending(party=%v, fee_rate=%v)",
                c.Party, c.FeeRate)
}

// isType returns true if the value is of type T.
func isType[T any](value any) bool {
        _, ok := value.(T)
        return ok
}

// ShouldRouteTo returns true if the target state should process the target
// event.
func (c *ClosePending) ShouldRouteTo(event ProtocolEvent) bool {
        switch event.(type) {
        case *SpendEvent:
                return true
        default:
                switch {
                case c.Party == lntypes.Local && isType[*SendOfferEvent](event):
                        return true

                case c.Party == lntypes.Remote && isType[*OfferReceivedEvent](
                        event,
                ):

                        return true
                }

                return false
        }
}

// protocolStateSealed indicates that this struct is a ProtocolEvent instance.
func (c *ClosePending) protocolStateSealed() {}

// IsTerminal returns true if the target state is a terminal state.
func (c *ClosePending) IsTerminal() bool {
        return true
}

// CloseFin is the terminal state for the channel closer state machine. At this
// point, the close tx has been confirmed on chain.
type CloseFin struct {
        // ConfirmedTx is the transaction that confirmed the channel close.
        ConfirmedTx *wire.MsgTx
}

// String returns the name of the state for CloseFin.
func (c *CloseFin) String() string {
        return "CloseFin"
}

// protocolStateSealed indicates that this struct is a ProtocolEvent instance.
func (c *CloseFin) protocolStateSealed() {}

// IsTerminal returns true if the target state is a terminal state.
func (c *CloseFin) IsTerminal() bool {
        return true
}

// RemoteCloseStart is similar to the LocalCloseStart, but is used to drive the
// process of signing an offer for the remote party
//
// transition:
//   - fromState: ChannelFlushing
//   - toState: ClosePending
type RemoteCloseStart struct {
        *CloseChannelTerms
}

// String returns the name of the state for RemoteCloseStart.
func (r *RemoteCloseStart) String() string {
        return "RemoteCloseStart"
}

// ShouldRouteTo returns true if the target state should process the target
// event.
func (l *RemoteCloseStart) ShouldRouteTo(event ProtocolEvent) bool {
        switch event.(type) {
        case *OfferReceivedEvent:
                return true
        default:
                return false
        }
}

// protocolStateSealed indicates that this struct is a ProtocolEvent instance.
func (l *RemoteCloseStart) protocolStateSealed() {}

// IsTerminal returns true if the target state is a terminal state.
func (l *RemoteCloseStart) IsTerminal() bool {
        return false
}

// CloseErr is an error state in the protocol. We enter this state when a
// protocol constraint is violated, or an upfront sanity check fails.
type CloseErr struct {
        ErrState

        *CloseChannelTerms

        // Party indicates which party is at this state. This is used to
        // implement the state transition properly, based on ShouldRouteTo.
        Party lntypes.ChannelParty
}

// String returns the name of the state for CloseErr, including error and party
// details.
func (c *CloseErr) String() string {
        return fmt.Sprintf("CloseErr(Party: %v, Error: %v)", c.Party, c.Err())
}

// ShouldRouteTo returns true if the target state should process the target
// event.
func (c *CloseErr) ShouldRouteTo(event ProtocolEvent) bool {
        switch event.(type) {
        case *SpendEvent:
                return true
        default:
                switch {
                case c.Party == lntypes.Local && isType[*SendOfferEvent](event):
                        return true

                case c.Party == lntypes.Remote && isType[*OfferReceivedEvent](
                        event,
                ):

                        return true
                }

                return false
        }
}

// protocolStateSealed indicates that this struct is a ProtocolEvent instance.
func (c *CloseErr) protocolStateSealed() {}

// IsTerminal returns true if the target state is a terminal state.
func (c *CloseErr) IsTerminal() bool {
        return true
}

// RbfChanCloser is a state machine that handles the RBF-enabled cooperative
// channel close protocol.
type RbfChanCloser = protofsm.StateMachine[ProtocolEvent, *Environment]

// RbfChanCloserCfg is a configuration struct that is used to initialize a new
// RBF chan closer state machine.
type RbfChanCloserCfg = protofsm.StateMachineCfg[ProtocolEvent, *Environment]

// RbfSpendMapper is a type used to map the generic spend event to one specific
// to this package.
type RbfSpendMapper = protofsm.SpendMapper[ProtocolEvent]

func SpendMapper(spendEvent *chainntnfs.SpendDetail) ProtocolEvent {
        return &SpendEvent{
                Tx:          spendEvent.SpendingTx,
                BlockHeight: uint32(spendEvent.SpendingHeight),
        }
}

// RbfMsgMapperT is a type used to map incoming wire messages to protocol
// events.
type RbfMsgMapperT = protofsm.MsgMapper[ProtocolEvent]

// RbfState is a type alias for the state of the RBF channel closer.
type RbfState = protofsm.State[ProtocolEvent, *Environment]

// RbfEvent is a type alias for the event type of the RBF channel closer.
type RbfEvent = protofsm.EmittedEvent[ProtocolEvent]

lightningnetwork / lnd / 13558005087

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