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package lndclient
import (
"context"
"encoding/hex"
"fmt"
"time"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/routing/route"
"github.com/lightningnetwork/lnd/channeldb"
"google.golang.org/grpc/codes"
"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
"github.com/lightningnetwork/lnd/lnwire"
"google.golang.org/grpc"
"google.golang.org/grpc/status"
"github.com/btcsuite/btcutil"
"github.com/lightningnetwork/lnd/lntypes"
)
// RouterClient exposes payment functionality.
type RouterClient interface {
// SendPayment attempts to route a payment to the final destination. The
// call returns a payment update stream and an error stream.
SendPayment(ctx context.Context, request SendPaymentRequest) (
chan PaymentStatus, chan error, error)
// TrackPayment picks up a previously started payment and returns a
// payment update stream and an error stream.
TrackPayment(ctx context.Context, hash lntypes.Hash) (
chan PaymentStatus, chan error, error)
}
// PaymentStatus describe the state of a payment.
type PaymentStatus struct {
State routerrpc.PaymentState
Preimage lntypes.Preimage
Fee lnwire.MilliSatoshi
Route *route.Route
}
// SendPaymentRequest defines the payment parameters for a new payment.
type SendPaymentRequest struct {
Invoice string
MaxFee btcutil.Amount
MaxCltv *int32
OutgoingChannel *uint64
Timeout time.Duration
}
// routerClient is a wrapper around the generated routerrpc proxy.
type routerClient struct {
client routerrpc.RouterClient
routerKitMac serializedMacaroon
}
func newRouterClient(conn *grpc.ClientConn,
routerKitMac serializedMacaroon) *routerClient {
return &routerClient{
client: routerrpc.NewRouterClient(conn),
routerKitMac: routerKitMac,
}
}
// SendPayment attempts to route a payment to the final destination. The call
// returns a payment update stream and an error stream.
func (r *routerClient) SendPayment(ctx context.Context,
request SendPaymentRequest) (chan PaymentStatus, chan error, error) {
rpcCtx := r.routerKitMac.WithMacaroonAuth(ctx)
rpcReq := &routerrpc.SendPaymentRequest{
FeeLimitSat: int64(request.MaxFee),
PaymentRequest: request.Invoice,
TimeoutSeconds: int32(request.Timeout.Seconds()),
}
if request.MaxCltv != nil {
rpcReq.CltvLimit = *request.MaxCltv
}
if request.OutgoingChannel != nil {
rpcReq.OutgoingChanId = *request.OutgoingChannel
}
stream, err := r.client.SendPayment(rpcCtx, rpcReq)
if err != nil {
return nil, nil, err
}
return r.trackPayment(ctx, stream)
}
// TrackPayment picks up a previously started payment and returns a payment
// update stream and an error stream.
func (r *routerClient) TrackPayment(ctx context.Context,
hash lntypes.Hash) (chan PaymentStatus, chan error, error) {
ctx = r.routerKitMac.WithMacaroonAuth(ctx)
stream, err := r.client.TrackPayment(
ctx, &routerrpc.TrackPaymentRequest{
PaymentHash: hash[:],
},
)
if err != nil {
return nil, nil, err
}
return r.trackPayment(ctx, stream)
}
// trackPayment takes an update stream from either a SendPayment or a
// TrackPayment rpc call and converts it into distinct update and error streams.
func (r *routerClient) trackPayment(ctx context.Context,
stream routerrpc.Router_TrackPaymentClient) (chan PaymentStatus,
chan error, error) {
statusChan := make(chan PaymentStatus)
errorChan := make(chan error, 1)
go func() {
for {
rpcStatus, err := stream.Recv()
if err != nil {
switch status.Convert(err).Code() {
// NotFound is only expected as a response to
// TrackPayment.
case codes.NotFound:
err = channeldb.ErrPaymentNotInitiated
// NotFound is only expected as a response to
// SendPayment.
case codes.AlreadyExists:
err = channeldb.ErrAlreadyPaid
}
errorChan <- err
return
}
status, err := unmarshallPaymentStatus(rpcStatus)
if err != nil {
errorChan <- err
return
}
select {
case statusChan <- *status:
case <-ctx.Done():
return
}
}
}()
return statusChan, errorChan, nil
}
// unmarshallPaymentStatus converts an rpc status update to the PaymentStatus
// type that is used throughout the application.
func unmarshallPaymentStatus(rpcStatus *routerrpc.PaymentStatus) (
*PaymentStatus, error) {
status := PaymentStatus{
State: rpcStatus.State,
}
if status.State == routerrpc.PaymentState_SUCCEEDED {
preimage, err := lntypes.MakePreimage(
rpcStatus.Preimage,
)
if err != nil {
return nil, err
}
status.Preimage = preimage
status.Fee = lnwire.MilliSatoshi(
rpcStatus.Route.TotalFeesMsat,
)
if rpcStatus.Route != nil {
route, err := unmarshallRoute(rpcStatus.Route)
if err != nil {
return nil, err
}
status.Route = route
}
}
return &status, nil
}
// unmarshallRoute unmarshalls an rpc route.
func unmarshallRoute(rpcroute *lnrpc.Route) (
*route.Route, error) {
hops := make([]*route.Hop, len(rpcroute.Hops))
for i, hop := range rpcroute.Hops {
routeHop, err := unmarshallHop(hop)
if err != nil {
return nil, err
}
hops[i] = routeHop
}
// TODO(joostjager): Fetch self node from lnd.
selfNode := route.Vertex{}
route, err := route.NewRouteFromHops(
lnwire.MilliSatoshi(rpcroute.TotalAmtMsat),
rpcroute.TotalTimeLock,
selfNode,
hops,
)
if err != nil {
return nil, err
}
return route, nil
}
// unmarshallKnownPubkeyHop unmarshalls an rpc hop.
func unmarshallHop(hop *lnrpc.Hop) (*route.Hop, error) {
pubKey, err := hex.DecodeString(hop.PubKey)
if err != nil {
return nil, fmt.Errorf("cannot decode pubkey %s", hop.PubKey)
}
var pubKeyBytes [33]byte
copy(pubKeyBytes[:], pubKey)
return &route.Hop{
OutgoingTimeLock: hop.Expiry,
AmtToForward: lnwire.MilliSatoshi(hop.AmtToForwardMsat),
PubKeyBytes: pubKeyBytes,
ChannelID: hop.ChanId,
}, nil
}