reservations: add client requested fsm

Author: sputn1ck

instantout/reservation/actions.go

@@ -2,31 +2,194 @@ package reservation
 
 import (
 	"context"
+	"errors"
+	"fmt"
+	"time"
 
 	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/btcutil"
+	"github.com/lightninglabs/lndclient"
 	"github.com/lightninglabs/loop/fsm"
+	"github.com/lightninglabs/loop/swap"
 	"github.com/lightninglabs/loop/swapserverrpc"
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/lightningnetwork/lnd/lnrpc"
 )
 
-// InitReservationContext contains the request parameters for a reservation.
-type InitReservationContext struct {
+const (
+	// Define route independent max routing fees. We have currently no way
+	// to get a reliable estimate of the routing fees. Best we can do is
+	// the minimum routing fees, which is not very indicative.
+	maxRoutingFeeBase = btcutil.Amount(10)
+
+	maxRoutingFeeRate = int64(20000)
+)
+
+var (
+	// The allowed delta between what we accept as the expiry height and
+	// the actual expiry height.
+	expiryDelta = uint32(3)
+
+	// defaultPrepayTimeout is the default timeout for the prepayment.
+	DefaultPrepayTimeout = time.Minute * 120
+)
+
+// ClientRequestedInitContext contains the request parameters for a reservation.
+type ClientRequestedInitContext struct {
+	value            btcutil.Amount
+	relativeExpiry   uint32
+	heightHint       uint32
+	maxPrepaymentAmt btcutil.Amount
+}
+
+// InitFromClientRequestAction is the action that is executed when the
+// reservation state machine is initialized from a client request. It creates
+// the reservation in the database and sends the reservation request to the
+// server.
+func (f *FSM) InitFromClientRequestAction(ctx context.Context,
+	eventCtx fsm.EventContext) fsm.EventType {
+
+	// Check if the context is of the correct type.
+	reservationRequest, ok := eventCtx.(*ClientRequestedInitContext)
+	if !ok {
+		return f.HandleError(fsm.ErrInvalidContextType)
+	}
+
+	// Create the reservation in the database.
+	keyRes, err := f.cfg.Wallet.DeriveNextKey(ctx, KeyFamily)
+	if err != nil {
+		return f.HandleError(err)
+	}
+
+	// Send the request to the server.
+	requestResponse, err := f.cfg.ReservationClient.RequestReservation(
+		ctx, &swapserverrpc.RequestReservationRequest{
+			Value:     uint64(reservationRequest.value),
+			Expiry:    reservationRequest.relativeExpiry,
+			ClientKey: keyRes.PubKey.SerializeCompressed(),
+		},
+	)
+	if err != nil {
+		return f.HandleError(err)
+	}
+
+	expectedExpiry := reservationRequest.relativeExpiry +
+		reservationRequest.heightHint
+
+	// Check that the expiry is in the delta.
+	if requestResponse.Expiry < expectedExpiry-expiryDelta ||
+		requestResponse.Expiry > expectedExpiry+expiryDelta {
+
+		return f.HandleError(
+			fmt.Errorf("unexpected expiry height: %v, expected %v",
+				requestResponse.Expiry, expectedExpiry))
+	}
+
+	prepayment, err := f.cfg.LightningClient.DecodePaymentRequest(
+		ctx, requestResponse.Invoice,
+	)
+	if err != nil {
+		return f.HandleError(err)
+	}
+
+	if prepayment.Value.ToSatoshis() > reservationRequest.maxPrepaymentAmt {
+		return f.HandleError(
+			errors.New("prepayment amount too high"))
+	}
+
+	serverKey, err := btcec.ParsePubKey(requestResponse.ServerKey)
+	if err != nil {
+		return f.HandleError(err)
+	}
+
+	var Id ID
+	copy(Id[:], requestResponse.ReservationId)
+
+	reservation, err := NewReservation(
+		Id, serverKey, keyRes.PubKey, reservationRequest.value,
+		requestResponse.Expiry, reservationRequest.heightHint,
+		keyRes.KeyLocator, ProtocolVersionClientInitiated,
+	)
+	if err != nil {
+		return f.HandleError(err)
+	}
+	reservation.PrepayInvoice = requestResponse.Invoice
+	f.reservation = reservation
+
+	// Create the reservation in the database.
+	err = f.cfg.Store.CreateReservation(ctx, reservation)
+	if err != nil {
+		return f.HandleError(err)
+	}
+
+	return OnClientInitialized
+}
+
+// SendPrepayment is the action that is executed when the reservation
+// is initialized from a client request. It dispatches the prepayment to the
+// server and wait for it to be settled, signaling confirmation of the
+// reservation.
+func (f *FSM) SendPrepayment(ctx context.Context,
+	_ fsm.EventContext) fsm.EventType {
+
+	prepayment, err := f.cfg.LightningClient.DecodePaymentRequest(
+		ctx, f.reservation.PrepayInvoice,
+	)
+	if err != nil {
+		return f.HandleError(err)
+	}
+
+	payReq := lndclient.SendPaymentRequest{
+		Invoice: f.reservation.PrepayInvoice,
+		Timeout: DefaultPrepayTimeout,
+		MaxFee:  getMaxRoutingFee(prepayment.Value.ToSatoshis()),
+	}
+	// Send the prepayment to the server.
+	payChan, errChan, err := f.cfg.RouterClient.SendPayment(
+		ctx, payReq,
+	)
+	if err != nil {
+		return f.HandleError(err)
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return fsm.NoOp
+
+		case err := <-errChan:
+			return f.HandleError(err)
+
+		case prepayResp := <-payChan:
+			if prepayResp.State == lnrpc.Payment_FAILED {
+				return f.HandleError(
+					fmt.Errorf("prepayment failed: %v",
+						prepayResp.FailureReason))
+			}
+			if prepayResp.State == lnrpc.Payment_SUCCEEDED {
+				return OnBroadcast
+			}
+		}
+	}
+}
+
+// ServerRequestedInitContext contains the request parameters for a reservation.
+type ServerRequestedInitContext struct {
 	reservationID ID
 	serverPubkey  *btcec.PublicKey
 	value         btcutil.Amount
 	expiry        uint32
 	heightHint    uint32
 }
 
-// InitAction is the action that is executed when the reservation state machine
-// is initialized. It creates the reservation in the database and dispatches the
-// payment to the server.
-func (f *FSM) InitAction(ctx context.Context,
+// InitFromServerRequestAction is the action that is executed when the
+// reservation state machine is initialized from  a server request. It creates
+// the reservation in the database and dispatches the payment to the server.
+func (f *FSM) InitFromServerRequestAction(ctx context.Context,
 	eventCtx fsm.EventContext) fsm.EventType {
 
 	// Check if the context is of the correct type.
-	reservationRequest, ok := eventCtx.(*InitReservationContext)
+	reservationRequest, ok := eventCtx.(*ServerRequestedInitContext)
 	if !ok {
 		return f.HandleError(fsm.ErrInvalidContextType)
 	}
@@ -240,3 +403,7 @@ func (f *FSM) handleAsyncError(ctx context.Context, err error) {
 		f.Errorf("Error sending event: %v", err2)
 	}
 }
+
+func getMaxRoutingFee(amt btcutil.Amount) btcutil.Amount {
+	return swap.CalcFee(amt, maxRoutingFeeBase, maxRoutingFeeRate)
+}

instantout/reservation/actions_test.go

@@ -31,8 +31,8 @@ var (
 	defaultExpiry = uint32(100)
 )
 
-func newValidInitReservationContext() *InitReservationContext {
-	return &InitReservationContext{
+func newValidInitReservationContext() *ServerRequestedInitContext {
+	return &ServerRequestedInitContext{
 		reservationID: ID{0x01},
 		serverPubkey:  defaultPubkey,
 		value:         defaultValue,
@@ -174,7 +174,7 @@ func TestInitReservationAction(t *testing.T) {
 			StateMachine: &fsm.StateMachine{},
 		}
 
-		event := reservationFSM.InitAction(ctxb, tc.eventCtx)
+		event := reservationFSM.InitFromServerRequestAction(ctxb, tc.eventCtx)
 		require.Equal(t, tc.expectedEvent, event)
 	}
 }

instantout/reservation/fsm.go

@@ -17,6 +17,10 @@ const (
 	// ProtocolVersionServerInitiated is the protocol version where the
 	// server initiates the reservation.
 	ProtocolVersionServerInitiated ProtocolVersion = 1
+
+	// ProtocolVersionClientInitiated is the protocol version where the
+	// client initiates the reservation.
+	ProtocolVersionClientInitiated ProtocolVersion = 2
 )
 
 const (
@@ -39,6 +43,12 @@ type Config struct {
 	// swap server.
 	ReservationClient swapserverrpc.ReservationServiceClient
 
+	// LightningClient is the lnd client used to handle invoices decoding.
+	LightningClient lndclient.LightningClient
+
+	// RouterClient is used to send the offchain payments.
+	RouterClient lndclient.RouterClient
+
 	// NotificationManager is the manager that handles the notification
 	// subscriptions.
 	NotificationManager NotificationManager
@@ -75,6 +85,10 @@ func NewFSMFromReservation(cfg *Config, reservation *Reservation) *FSM {
 	switch reservation.ProtocolVersion {
 	case ProtocolVersionServerInitiated:
 		states = reservationFsm.GetServerInitiatedReservationStates()
+
+	case ProtocolVersionClientInitiated:
+		states = reservationFsm.GetClientInitiatedReservationStates()
+
 	default:
 		states = make(fsm.States)
 	}
@@ -93,6 +107,10 @@ var (
 	// Init is the initial state of the reservation.
 	Init = fsm.StateType("Init")
 
+	// SendPrepaymentPayment is the state where the client sends the payment to the
+	// server.
+	SendPrepaymentPayment = fsm.StateType("SendPayment")
+
 	// WaitForConfirmation is the state where we wait for the reservation
 	// tx to be confirmed.
 	WaitForConfirmation = fsm.StateType("WaitForConfirmation")
@@ -120,6 +138,10 @@ var (
 	// requests a new reservation.
 	OnServerRequest = fsm.EventType("OnServerRequest")
 
+	// OnClientInitialized is the event that is triggered when the client
+	// has initialized the reservation.
+	OnClientInitialized = fsm.EventType("OnClientInitialized")
+
 	// OnBroadcast is the event that is triggered when the reservation tx
 	// has been broadcast.
 	OnBroadcast = fsm.EventType("OnBroadcast")
@@ -153,6 +175,80 @@ var (
 	OnUnlocked = fsm.EventType("OnUnlocked")
 )
 
+// GetClientInitiatedReservationStates returns the statemap that defines the
+// reservation state machine, where the client initiates the reservation.
+func (f *FSM) GetClientInitiatedReservationStates() fsm.States {
+	return fsm.States{
+		fsm.EmptyState: fsm.State{
+			Transitions: fsm.Transitions{
+				OnClientInitialized: Init,
+			},
+			Action: nil,
+		},
+		Init: fsm.State{
+			Transitions: fsm.Transitions{
+				OnClientInitialized: SendPrepaymentPayment,
+				OnRecover:           Failed,
+				fsm.OnError:         Failed,
+			},
+			Action: f.InitFromClientRequestAction,
+		},
+		SendPrepaymentPayment: fsm.State{
+			Transitions: fsm.Transitions{
+				OnBroadcast: WaitForConfirmation,
+				OnRecover:   SendPrepaymentPayment,
+				fsm.OnError: Failed,
+			},
+			Action: f.SendPrepayment,
+		},
+		WaitForConfirmation: fsm.State{
+			Transitions: fsm.Transitions{
+				OnRecover:   WaitForConfirmation,
+				OnConfirmed: Confirmed,
+				OnTimedOut:  TimedOut,
+			},
+			Action: f.SubscribeToConfirmationAction,
+		},
+		Confirmed: fsm.State{
+			Transitions: fsm.Transitions{
+				OnSpent:     Spent,
+				OnTimedOut:  TimedOut,
+				OnRecover:   Confirmed,
+				OnLocked:    Locked,
+				fsm.OnError: Confirmed,
+			},
+			Action: f.AsyncWaitForExpiredOrSweptAction,
+		},
+		Locked: fsm.State{
+			Transitions: fsm.Transitions{
+				OnUnlocked:  Confirmed,
+				OnTimedOut:  TimedOut,
+				OnRecover:   Locked,
+				OnSpent:     Spent,
+				fsm.OnError: Locked,
+			},
+			Action: f.AsyncWaitForExpiredOrSweptAction,
+		},
+		TimedOut: fsm.State{
+			Transitions: fsm.Transitions{
+				OnTimedOut: TimedOut,
+			},
+			Action: fsm.NoOpAction,
+		},
+
+		Spent: fsm.State{
+			Transitions: fsm.Transitions{
+				OnSpent: Spent,
+			},
+			Action: fsm.NoOpAction,
+		},
+
+		Failed: fsm.State{
+			Action: fsm.NoOpAction,
+		},
+	}
+}
+
 // GetServerInitiatedReservationStates returns the statemap that defines the
 // reservation state machine, where the server initiates the reservation.
 func (f *FSM) GetServerInitiatedReservationStates() fsm.States {
@@ -169,7 +265,7 @@ func (f *FSM) GetServerInitiatedReservationStates() fsm.States {
 				OnRecover:   Failed,
 				fsm.OnError: Failed,
 			},
-			Action: f.InitAction,
+			Action: f.InitFromServerRequestAction,
 		},
 		WaitForConfirmation: fsm.State{
 			Transitions: fsm.Transitions{

instantout/reservation/reservation.go

@@ -62,6 +62,9 @@ type Reservation struct {
 	// Outpoint is the outpoint of the reservation.
 	Outpoint *wire.OutPoint
 
+	// PrepayInvoice is the invoice that the client paid as a prepayment.
+	PrepayInvoice string
+
 	// InitiationHeight is the height at which the reservation was
 	// initiated.
 	InitiationHeight int32