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fsm.go
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fsm.go
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package instantout
import (
"context"
"errors"
"github.com/btcsuite/btcd/chaincfg"
"github.com/lightninglabs/lndclient"
"github.com/lightninglabs/loop/fsm"
loop_rpc "github.com/lightninglabs/loop/swapserverrpc"
"github.com/lightningnetwork/lnd/input"
)
type ProtocolVersion uint32
const (
// ProtocolVersionUndefined is the undefined protocol version.
ProtocolVersionUndefined ProtocolVersion = 0
// ProtocolVersionFullReservation is the protocol version that uses
// the full reservation amount without change.
ProtocolVersionFullReservation ProtocolVersion = 1
)
// CurrentProtocolVersion returns the current protocol version.
func CurrentProtocolVersion() ProtocolVersion {
return ProtocolVersionFullReservation
}
// CurrentRpcProtocolVersion returns the current rpc protocol version.
func CurrentRpcProtocolVersion() loop_rpc.InstantOutProtocolVersion {
return loop_rpc.InstantOutProtocolVersion(CurrentProtocolVersion())
}
const (
// defaultObserverSize is the size of the fsm observer channel.
defaultObserverSize = 15
)
var (
ErrProtocolVersionNotSupported = errors.New(
"protocol version not supported",
)
)
// States.
var (
// Init is the initial state of the instant out FSM.
Init = fsm.StateType("Init")
// SendPaymentAndPollAccepted is the state where the payment is sent
// and the server is polled for the accepted state.
SendPaymentAndPollAccepted = fsm.StateType("SendPaymentAndPollAccepted")
// BuildHtlc is the state where the htlc transaction is built.
BuildHtlc = fsm.StateType("BuildHtlc")
// PushPreimage is the state where the preimage is pushed to the server.
PushPreimage = fsm.StateType("PushPreimage")
// WaitForSweeplessSweepConfirmed is the state where we wait for the
// sweepless sweep to be confirmed.
WaitForSweeplessSweepConfirmed = fsm.StateType(
"WaitForSweeplessSweepConfirmed")
// FinishedSweeplessSweep is the state where the swap is finished by
// publishing the sweepless sweep.
FinishedSweeplessSweep = fsm.StateType("FinishedSweeplessSweep")
// PublishHtlc is the state where the htlc transaction is published.
PublishHtlc = fsm.StateType("PublishHtlc")
// PublishHtlcSweep is the state where the htlc sweep transaction is
// published.
PublishHtlcSweep = fsm.StateType("PublishHtlcSweep")
// FinishedHtlcPreimageSweep is the state where the swap is finished by
// publishing the htlc preimage sweep.
FinishedHtlcPreimageSweep = fsm.StateType("FinishedHtlcPreimageSweep")
// WaitForHtlcSweepConfirmed is the state where we wait for the htlc
// sweep to be confirmed.
WaitForHtlcSweepConfirmed = fsm.StateType("WaitForHtlcSweepConfirmed")
// FailedHtlcSweep is the state where the htlc sweep failed.
FailedHtlcSweep = fsm.StateType("FailedHtlcSweep")
// Failed is the state where the swap failed.
Failed = fsm.StateType("InstantOutFailed")
)
// Events.
var (
// OnStart is the event that is sent when the FSM is started.
OnStart = fsm.EventType("OnStart")
// OnInit is the event that is triggered when the FSM is initialized.
OnInit = fsm.EventType("OnInit")
// OnPaymentAccepted is the event that is triggered when the payment
// is accepted by the server.
OnPaymentAccepted = fsm.EventType("OnPaymentAccepted")
// OnHtlcSigReceived is the event that is triggered when the htlc sig
// is received.
OnHtlcSigReceived = fsm.EventType("OnHtlcSigReceived")
// OnPreimagePushed is the event that is triggered when the preimage
// is pushed to the server.
OnPreimagePushed = fsm.EventType("OnPreimagePushed")
// OnSweeplessSweepPublished is the event that is triggered when the
// sweepless sweep is published.
OnSweeplessSweepPublished = fsm.EventType("OnSweeplessSweepPublished")
// OnSweeplessSweepConfirmed is the event that is triggered when the
// sweepless sweep is confirmed.
OnSweeplessSweepConfirmed = fsm.EventType("OnSweeplessSweepConfirmed")
// OnErrorPublishHtlc is the event that is triggered when the htlc
// sweep is published after an error.
OnErrorPublishHtlc = fsm.EventType("OnErrorPublishHtlc")
// OnInvalidCoopSweep is the event that is triggered when the coop
// sweep is invalid.
OnInvalidCoopSweep = fsm.EventType("OnInvalidCoopSweep")
// OnHtlcPublished is the event that is triggered when the htlc
// transaction is published.
OnHtlcPublished = fsm.EventType("OnHtlcPublished")
// OnHtlcSweepPublished is the event that is triggered when the htlc
// sweep is published.
OnHtlcSweepPublished = fsm.EventType("OnHtlcSweepPublished")
// OnHtlcSwept is the event that is triggered when the htlc sweep is
// confirmed.
OnHtlcSwept = fsm.EventType("OnHtlcSwept")
// OnRecover is the event that is triggered when the FSM recovers from
// a restart.
OnRecover = fsm.EventType("OnRecover")
)
// Config contains the services required for the instant out FSM.
type Config struct {
// Store is used to store the instant out.
Store InstantLoopOutStore
// LndClient is used to decode the swap invoice.
LndClient lndclient.LightningClient
// RouterClient is used to send the offchain payment to the server.
RouterClient lndclient.RouterClient
// ChainNotifier is used to be notified of on-chain events.
ChainNotifier lndclient.ChainNotifierClient
// Signer is used to sign transactions.
Signer lndclient.SignerClient
// Wallet is used to derive keys.
Wallet lndclient.WalletKitClient
// InstantOutClient is used to communicate with the swap server.
InstantOutClient loop_rpc.InstantSwapServerClient
// ReservationManager is used to get the reservations and lock them.
ReservationManager ReservationManager
// Network is the network that is used for the swap.
Network *chaincfg.Params
}
// FSM is the state machine that handles the instant out.
type FSM struct {
*fsm.StateMachine
ctx context.Context
// cfg contains all the services that the reservation manager needs to
// operate.
cfg *Config
// InstantOut contains all the information about the instant out.
InstantOut *InstantOut
// htlcMusig2Sessions contains all the reservations input musig2
// sessions that will be used for the htlc transaction.
htlcMusig2Sessions []*input.MuSig2SessionInfo
// sweeplessSweepSessions contains all the reservations input musig2
// sessions that will be used for the sweepless sweep transaction.
sweeplessSweepSessions []*input.MuSig2SessionInfo
}
// NewFSM creates a new instant out FSM.
func NewFSM(ctx context.Context, cfg *Config,
protocolVersion ProtocolVersion) (*FSM, error) {
instantOut := &InstantOut{
State: fsm.EmptyState,
protocolVersion: protocolVersion,
}
return NewFSMFromInstantOut(ctx, cfg, instantOut)
}
// NewFSMFromInstantOut creates a new instantout FSM from an existing instantout
// recovered from the database.
func NewFSMFromInstantOut(ctx context.Context, cfg *Config,
instantOut *InstantOut) (*FSM, error) {
instantOutFSM := &FSM{
ctx: ctx,
cfg: cfg,
InstantOut: instantOut,
}
switch instantOut.protocolVersion {
case ProtocolVersionFullReservation:
instantOutFSM.StateMachine = fsm.NewStateMachineWithState(
instantOutFSM.GetV1ReservationStates(),
instantOut.State, defaultObserverSize,
)
default:
return nil, ErrProtocolVersionNotSupported
}
instantOutFSM.ActionEntryFunc = instantOutFSM.updateInstantOut
return instantOutFSM, nil
}
// GetV1ReservationStates returns the states for the v1 reservation.
func (f *FSM) GetV1ReservationStates() fsm.States {
return fsm.States{
fsm.EmptyState: fsm.State{
Transitions: fsm.Transitions{
OnStart: Init,
},
Action: nil,
},
Init: fsm.State{
Transitions: fsm.Transitions{
OnInit: SendPaymentAndPollAccepted,
fsm.OnError: Failed,
OnRecover: Failed,
},
Action: f.InitInstantOutAction,
},
SendPaymentAndPollAccepted: fsm.State{
Transitions: fsm.Transitions{
OnPaymentAccepted: BuildHtlc,
fsm.OnError: Failed,
OnRecover: Failed,
},
Action: f.PollPaymentAcceptedAction,
},
BuildHtlc: fsm.State{
Transitions: fsm.Transitions{
OnHtlcSigReceived: PushPreimage,
fsm.OnError: Failed,
OnRecover: Failed,
},
Action: f.BuildHTLCAction,
},
PushPreimage: fsm.State{
Transitions: fsm.Transitions{
OnSweeplessSweepPublished: WaitForSweeplessSweepConfirmed,
fsm.OnError: Failed,
OnErrorPublishHtlc: PublishHtlc,
OnRecover: PushPreimage,
},
Action: f.PushPreimageAction,
},
WaitForSweeplessSweepConfirmed: fsm.State{
Transitions: fsm.Transitions{
OnSweeplessSweepConfirmed: FinishedSweeplessSweep,
OnRecover: WaitForSweeplessSweepConfirmed,
fsm.OnError: PublishHtlc,
},
Action: f.WaitForSweeplessSweepConfirmedAction,
},
FinishedSweeplessSweep: fsm.State{
Transitions: fsm.Transitions{},
Action: fsm.NoOpAction,
},
PublishHtlc: fsm.State{
Transitions: fsm.Transitions{
fsm.OnError: FailedHtlcSweep,
OnRecover: PublishHtlc,
OnHtlcPublished: PublishHtlcSweep,
},
Action: f.PublishHtlcAction,
},
PublishHtlcSweep: fsm.State{
Transitions: fsm.Transitions{
OnHtlcSweepPublished: WaitForHtlcSweepConfirmed,
OnRecover: PublishHtlcSweep,
fsm.OnError: FailedHtlcSweep,
},
Action: f.PublishHtlcSweepAction,
},
WaitForHtlcSweepConfirmed: fsm.State{
Transitions: fsm.Transitions{
OnHtlcSwept: FinishedHtlcPreimageSweep,
OnRecover: WaitForHtlcSweepConfirmed,
fsm.OnError: FailedHtlcSweep,
},
Action: f.WaitForHtlcSweepConfirmedAction,
},
FinishedHtlcPreimageSweep: fsm.State{
Transitions: fsm.Transitions{},
Action: fsm.NoOpAction,
},
FailedHtlcSweep: fsm.State{
Action: fsm.NoOpAction,
Transitions: fsm.Transitions{
OnRecover: PublishHtlcSweep,
},
},
Failed: fsm.State{
Action: fsm.NoOpAction,
},
}
}
// updateInstantOut is called after every action and updates the reservation
// in the db.
func (f *FSM) updateInstantOut(notification fsm.Notification) {
f.Infof("Previous: %v, Event: %v, Next: %v", notification.PreviousState,
notification.Event, notification.NextState)
// Skip the update if the reservation is not yet initialized.
if f.InstantOut == nil {
return
}
f.InstantOut.State = notification.NextState
// If we're in the early stages we don't have created the reservation
// in the store yet and won't need to update it.
if f.InstantOut.State == Init ||
f.InstantOut.State == fsm.EmptyState ||
(notification.PreviousState == Init &&
f.InstantOut.State == Failed) {
return
}
err := f.cfg.Store.UpdateInstantLoopOut(f.ctx, f.InstantOut)
if err != nil {
log.Errorf("Error updating instant out: %v", err)
return
}
}
// Infof logs an info message with the reservation hash as prefix.
func (f *FSM) Infof(format string, args ...interface{}) {
log.Infof(
"InstantOut %v: "+format,
append(
[]interface{}{f.InstantOut.swapPreimage.Hash()},
args...,
)...,
)
}
// Debugf logs a debug message with the reservation hash as prefix.
func (f *FSM) Debugf(format string, args ...interface{}) {
log.Debugf(
"InstantOut %v: "+format,
append(
[]interface{}{f.InstantOut.swapPreimage.Hash()},
args...,
)...,
)
}
// Errorf logs an error message with the reservation hash as prefix.
func (f *FSM) Errorf(format string, args ...interface{}) {
log.Errorf(
"InstantOut %v: "+format,
append(
[]interface{}{f.InstantOut.swapPreimage.Hash()},
args...,
)...,
)
}
// isFinalState returns true if the state is a final state.
func isFinalState(state fsm.StateType) bool {
switch state {
case Failed, FinishedHtlcPreimageSweep,
FinishedSweeplessSweep:
return true
}
return false
}