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router_server.go
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router_server.go
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package routerrpc
import (
"context"
"errors"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"sync/atomic"
"github.com/btcsuite/btcutil"
"github.com/grpc-ecosystem/grpc-gateway/runtime"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/macaroons"
"github.com/lightningnetwork/lnd/routing"
"github.com/lightningnetwork/lnd/routing/route"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
"gopkg.in/macaroon-bakery.v2/bakery"
)
const (
// subServerName is the name of the sub rpc server. We'll use this name
// to register ourselves, and we also require that the main
// SubServerConfigDispatcher instance recognize as the name of our
subServerName = "RouterRPC"
)
var (
errServerShuttingDown = errors.New("routerrpc server shutting down")
// ErrInterceptorAlreadyExists is an error returned when the a new stream
// is opened and there is already one active interceptor.
// The user must disconnect prior to open another stream.
ErrInterceptorAlreadyExists = errors.New("interceptor already exists")
// macaroonOps are the set of capabilities that our minted macaroon (if
// it doesn't already exist) will have.
macaroonOps = []bakery.Op{
{
Entity: "offchain",
Action: "read",
},
{
Entity: "offchain",
Action: "write",
},
}
// macPermissions maps RPC calls to the permissions they require.
macPermissions = map[string][]bakery.Op{
"/routerrpc.Router/SendPaymentV2": {{
Entity: "offchain",
Action: "write",
}},
"/routerrpc.Router/SendToRouteV2": {{
Entity: "offchain",
Action: "write",
}},
"/routerrpc.Router/SendToRoute": {{
Entity: "offchain",
Action: "write",
}},
"/routerrpc.Router/TrackPaymentV2": {{
Entity: "offchain",
Action: "read",
}},
"/routerrpc.Router/EstimateRouteFee": {{
Entity: "offchain",
Action: "read",
}},
"/routerrpc.Router/QueryMissionControl": {{
Entity: "offchain",
Action: "read",
}},
"/routerrpc.Router/QueryProbability": {{
Entity: "offchain",
Action: "read",
}},
"/routerrpc.Router/ResetMissionControl": {{
Entity: "offchain",
Action: "write",
}},
"/routerrpc.Router/BuildRoute": {{
Entity: "offchain",
Action: "read",
}},
"/routerrpc.Router/SubscribeHtlcEvents": {{
Entity: "offchain",
Action: "read",
}},
"/routerrpc.Router/SendPayment": {{
Entity: "offchain",
Action: "write",
}},
"/routerrpc.Router/TrackPayment": {{
Entity: "offchain",
Action: "read",
}},
"/routerrpc.Router/HtlcInterceptor": {{
Entity: "offchain",
Action: "write",
}},
}
// DefaultRouterMacFilename is the default name of the router macaroon
// that we expect to find via a file handle within the main
// configuration file in this package.
DefaultRouterMacFilename = "router.macaroon"
)
// Server is a stand alone sub RPC server which exposes functionality that
// allows clients to route arbitrary payment through the Lightning Network.
type Server struct {
started int32 // To be used atomically.
shutdown int32 // To be used atomically.
forwardInterceptorActive int32 // To be used atomically.
cfg *Config
quit chan struct{}
}
// A compile time check to ensure that Server fully implements the RouterServer
// gRPC service.
var _ RouterServer = (*Server)(nil)
// New creates a new instance of the RouterServer given a configuration struct
// that contains all external dependencies. If the target macaroon exists, and
// we're unable to create it, then an error will be returned. We also return
// the set of permissions that we require as a server. At the time of writing
// of this documentation, this is the same macaroon as as the admin macaroon.
func New(cfg *Config) (*Server, lnrpc.MacaroonPerms, error) {
// If the path of the router macaroon wasn't generated, then we'll
// assume that it's found at the default network directory.
if cfg.RouterMacPath == "" {
cfg.RouterMacPath = filepath.Join(
cfg.NetworkDir, DefaultRouterMacFilename,
)
}
// Now that we know the full path of the router macaroon, we can check
// to see if we need to create it or not. If stateless_init is set
// then we don't write the macaroons.
macFilePath := cfg.RouterMacPath
if cfg.MacService != nil && !cfg.MacService.StatelessInit &&
!lnrpc.FileExists(macFilePath) {
log.Infof("Making macaroons for Router RPC Server at: %v",
macFilePath)
// At this point, we know that the router macaroon doesn't yet,
// exist, so we need to create it with the help of the main
// macaroon service.
routerMac, err := cfg.MacService.NewMacaroon(
context.Background(), macaroons.DefaultRootKeyID,
macaroonOps...,
)
if err != nil {
return nil, nil, err
}
routerMacBytes, err := routerMac.M().MarshalBinary()
if err != nil {
return nil, nil, err
}
err = ioutil.WriteFile(macFilePath, routerMacBytes, 0644)
if err != nil {
_ = os.Remove(macFilePath)
return nil, nil, err
}
}
routerServer := &Server{
cfg: cfg,
quit: make(chan struct{}),
}
return routerServer, macPermissions, nil
}
// Start launches any helper goroutines required for the rpcServer to function.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (s *Server) Start() error {
if atomic.AddInt32(&s.started, 1) != 1 {
return nil
}
return nil
}
// Stop signals any active goroutines for a graceful closure.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (s *Server) Stop() error {
if atomic.AddInt32(&s.shutdown, 1) != 1 {
return nil
}
close(s.quit)
return nil
}
// Name returns a unique string representation of the sub-server. This can be
// used to identify the sub-server and also de-duplicate them.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (s *Server) Name() string {
return subServerName
}
// RegisterWithRootServer will be called by the root gRPC server to direct a
// sub RPC server to register itself with the main gRPC root server. Until this
// is called, each sub-server won't be able to have requests routed towards it.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (s *Server) RegisterWithRootServer(grpcServer *grpc.Server) error {
// We make sure that we register it with the main gRPC server to ensure
// all our methods are routed properly.
RegisterRouterServer(grpcServer, s)
log.Debugf("Router RPC server successfully register with root gRPC " +
"server")
return nil
}
// RegisterWithRestServer will be called by the root REST mux to direct a sub
// RPC server to register itself with the main REST mux server. Until this is
// called, each sub-server won't be able to have requests routed towards it.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (s *Server) RegisterWithRestServer(ctx context.Context,
mux *runtime.ServeMux, dest string, opts []grpc.DialOption) error {
// We make sure that we register it with the main REST server to ensure
// all our methods are routed properly.
err := RegisterRouterHandlerFromEndpoint(ctx, mux, dest, opts)
if err != nil {
log.Errorf("Could not register Router REST server "+
"with root REST server: %v", err)
return err
}
log.Debugf("Router REST server successfully registered with " +
"root REST server")
return nil
}
// SendPaymentV2 attempts to route a payment described by the passed
// PaymentRequest to the final destination. If we are unable to route the
// payment, or cannot find a route that satisfies the constraints in the
// PaymentRequest, then an error will be returned. Otherwise, the payment
// pre-image, along with the final route will be returned.
func (s *Server) SendPaymentV2(req *SendPaymentRequest,
stream Router_SendPaymentV2Server) error {
payment, err := s.cfg.RouterBackend.extractIntentFromSendRequest(req)
if err != nil {
return err
}
err = s.cfg.Router.SendPaymentAsync(payment)
if err != nil {
// Transform user errors to grpc code.
if err == channeldb.ErrPaymentInFlight ||
err == channeldb.ErrAlreadyPaid {
log.Debugf("SendPayment async result for hash %x: %v",
payment.PaymentHash, err)
return status.Error(
codes.AlreadyExists, err.Error(),
)
}
log.Errorf("SendPayment async error for hash %x: %v",
payment.PaymentHash, err)
return err
}
return s.trackPayment(payment.PaymentHash, stream, req.NoInflightUpdates)
}
// EstimateRouteFee allows callers to obtain a lower bound w.r.t how much it
// may cost to send an HTLC to the target end destination.
func (s *Server) EstimateRouteFee(ctx context.Context,
req *RouteFeeRequest) (*RouteFeeResponse, error) {
if len(req.Dest) != 33 {
return nil, errors.New("invalid length destination key")
}
var destNode route.Vertex
copy(destNode[:], req.Dest)
// Next, we'll convert the amount in satoshis to mSAT, which are the
// native unit of LN.
amtMsat := lnwire.NewMSatFromSatoshis(btcutil.Amount(req.AmtSat))
// Pick a fee limit
//
// TODO: Change this into behaviour that makes more sense.
feeLimit := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
// Finally, we'll query for a route to the destination that can carry
// that target amount, we'll only request a single route. Set a
// restriction for the default CLTV limit, otherwise we can find a route
// that exceeds it and is useless to us.
mc := s.cfg.RouterBackend.MissionControl
route, err := s.cfg.Router.FindRoute(
s.cfg.RouterBackend.SelfNode, destNode, amtMsat,
&routing.RestrictParams{
FeeLimit: feeLimit,
CltvLimit: s.cfg.RouterBackend.MaxTotalTimelock,
ProbabilitySource: mc.GetProbability,
}, nil, nil, s.cfg.RouterBackend.DefaultFinalCltvDelta,
)
if err != nil {
return nil, err
}
return &RouteFeeResponse{
RoutingFeeMsat: int64(route.TotalFees()),
TimeLockDelay: int64(route.TotalTimeLock),
}, nil
}
// SendToRouteV2 sends a payment through a predefined route. The response of this
// call contains structured error information.
func (s *Server) SendToRouteV2(ctx context.Context,
req *SendToRouteRequest) (*lnrpc.HTLCAttempt, error) {
if req.Route == nil {
return nil, fmt.Errorf("unable to send, no routes provided")
}
route, err := s.cfg.RouterBackend.UnmarshallRoute(req.Route)
if err != nil {
return nil, err
}
hash, err := lntypes.MakeHash(req.PaymentHash)
if err != nil {
return nil, err
}
// Pass route to the router. This call returns the full htlc attempt
// information as it is stored in the database. It is possible that both
// the attempt return value and err are non-nil. This can happen when
// the attempt was already initiated before the error happened. In that
// case, we give precedence to the attempt information as stored in the
// db.
attempt, err := s.cfg.Router.SendToRoute(hash, route)
if attempt != nil {
rpcAttempt, err := s.cfg.RouterBackend.MarshalHTLCAttempt(
*attempt,
)
if err != nil {
return nil, err
}
return rpcAttempt, nil
}
// Transform user errors to grpc code.
if err == channeldb.ErrPaymentInFlight ||
err == channeldb.ErrAlreadyPaid {
return nil, status.Error(codes.AlreadyExists, err.Error())
}
return nil, err
}
// ResetMissionControl clears all mission control state and starts with a clean
// slate.
func (s *Server) ResetMissionControl(ctx context.Context,
req *ResetMissionControlRequest) (*ResetMissionControlResponse, error) {
err := s.cfg.RouterBackend.MissionControl.ResetHistory()
if err != nil {
return nil, err
}
return &ResetMissionControlResponse{}, nil
}
// QueryMissionControl exposes the internal mission control state to callers. It
// is a development feature.
func (s *Server) QueryMissionControl(ctx context.Context,
req *QueryMissionControlRequest) (*QueryMissionControlResponse, error) {
snapshot := s.cfg.RouterBackend.MissionControl.GetHistorySnapshot()
rpcPairs := make([]*PairHistory, 0, len(snapshot.Pairs))
for _, p := range snapshot.Pairs {
// Prevent binding to loop variable.
pair := p
rpcPair := PairHistory{
NodeFrom: pair.Pair.From[:],
NodeTo: pair.Pair.To[:],
History: toRPCPairData(&pair.TimedPairResult),
}
rpcPairs = append(rpcPairs, &rpcPair)
}
response := QueryMissionControlResponse{
Pairs: rpcPairs,
}
return &response, nil
}
// toRPCPairData marshalls mission control pair data to the rpc struct.
func toRPCPairData(data *routing.TimedPairResult) *PairData {
rpcData := PairData{
FailAmtSat: int64(data.FailAmt.ToSatoshis()),
FailAmtMsat: int64(data.FailAmt),
SuccessAmtSat: int64(data.SuccessAmt.ToSatoshis()),
SuccessAmtMsat: int64(data.SuccessAmt),
}
if !data.FailTime.IsZero() {
rpcData.FailTime = data.FailTime.Unix()
}
if !data.SuccessTime.IsZero() {
rpcData.SuccessTime = data.SuccessTime.Unix()
}
return &rpcData
}
// QueryProbability returns the current success probability estimate for a
// given node pair and amount.
func (s *Server) QueryProbability(ctx context.Context,
req *QueryProbabilityRequest) (*QueryProbabilityResponse, error) {
fromNode, err := route.NewVertexFromBytes(req.FromNode)
if err != nil {
return nil, err
}
toNode, err := route.NewVertexFromBytes(req.ToNode)
if err != nil {
return nil, err
}
amt := lnwire.MilliSatoshi(req.AmtMsat)
mc := s.cfg.RouterBackend.MissionControl
prob := mc.GetProbability(fromNode, toNode, amt)
history := mc.GetPairHistorySnapshot(fromNode, toNode)
return &QueryProbabilityResponse{
Probability: prob,
History: toRPCPairData(&history),
}, nil
}
// TrackPaymentV2 returns a stream of payment state updates. The stream is
// closed when the payment completes.
func (s *Server) TrackPaymentV2(request *TrackPaymentRequest,
stream Router_TrackPaymentV2Server) error {
paymentHash, err := lntypes.MakeHash(request.PaymentHash)
if err != nil {
return err
}
log.Debugf("TrackPayment called for payment %v", paymentHash)
return s.trackPayment(paymentHash, stream, request.NoInflightUpdates)
}
// trackPayment writes payment status updates to the provided stream.
func (s *Server) trackPayment(paymentHash lntypes.Hash,
stream Router_TrackPaymentV2Server, noInflightUpdates bool) error {
router := s.cfg.RouterBackend
// Subscribe to the outcome of this payment.
subscription, err := router.Tower.SubscribePayment(
paymentHash,
)
switch {
case err == channeldb.ErrPaymentNotInitiated:
return status.Error(codes.NotFound, err.Error())
case err != nil:
return err
}
defer subscription.Close()
// Stream updates back to the client. The first update is always the
// current state of the payment.
for {
select {
case item, ok := <-subscription.Updates:
if !ok {
// No more payment updates.
return nil
}
result := item.(*channeldb.MPPayment)
// Skip in-flight updates unless requested.
if noInflightUpdates &&
result.Status == channeldb.StatusInFlight {
continue
}
rpcPayment, err := router.MarshallPayment(result)
if err != nil {
return err
}
// Send event to the client.
err = stream.Send(rpcPayment)
if err != nil {
return err
}
case <-s.quit:
return errServerShuttingDown
case <-stream.Context().Done():
log.Debugf("Payment status stream %v canceled", paymentHash)
return stream.Context().Err()
}
}
}
// BuildRoute builds a route from a list of hop addresses.
func (s *Server) BuildRoute(ctx context.Context,
req *BuildRouteRequest) (*BuildRouteResponse, error) {
// Unmarshall hop list.
hops := make([]route.Vertex, len(req.HopPubkeys))
for i, pubkeyBytes := range req.HopPubkeys {
pubkey, err := route.NewVertexFromBytes(pubkeyBytes)
if err != nil {
return nil, err
}
hops[i] = pubkey
}
// Prepare BuildRoute call parameters from rpc request.
var amt *lnwire.MilliSatoshi
if req.AmtMsat != 0 {
rpcAmt := lnwire.MilliSatoshi(req.AmtMsat)
amt = &rpcAmt
}
var outgoingChan *uint64
if req.OutgoingChanId != 0 {
outgoingChan = &req.OutgoingChanId
}
var payAddr *[32]byte
if len(req.PaymentAddr) != 0 {
var backingPayAddr [32]byte
copy(backingPayAddr[:], req.PaymentAddr)
payAddr = &backingPayAddr
}
// Build the route and return it to the caller.
route, err := s.cfg.Router.BuildRoute(
amt, hops, outgoingChan, req.FinalCltvDelta, payAddr,
)
if err != nil {
return nil, err
}
rpcRoute, err := s.cfg.RouterBackend.MarshallRoute(route)
if err != nil {
return nil, err
}
routeResp := &BuildRouteResponse{
Route: rpcRoute,
}
return routeResp, nil
}
// SubscribeHtlcEvents creates a uni-directional stream from the server to
// the client which delivers a stream of htlc events.
func (s *Server) SubscribeHtlcEvents(req *SubscribeHtlcEventsRequest,
stream Router_SubscribeHtlcEventsServer) error {
htlcClient, err := s.cfg.RouterBackend.SubscribeHtlcEvents()
if err != nil {
return err
}
defer htlcClient.Cancel()
for {
select {
case event := <-htlcClient.Updates():
rpcEvent, err := rpcHtlcEvent(event)
if err != nil {
return err
}
if err := stream.Send(rpcEvent); err != nil {
return err
}
// If the stream's context is cancelled, return an error.
case <-stream.Context().Done():
log.Debugf("htlc event stream cancelled")
return stream.Context().Err()
// If the subscribe client terminates, exit with an error.
case <-htlcClient.Quit():
return errors.New("htlc event subscription terminated")
// If the server has been signalled to shut down, exit.
case <-s.quit:
return errServerShuttingDown
}
}
}
// HtlcInterceptor is a bidirectional stream for streaming interception
// requests to the caller.
// Upon connection it does the following:
// 1. Check if there is already a live stream, if yes it rejects the request.
// 2. Regsitered a ForwardInterceptor
// 3. Delivers to the caller every √√ and detect his answer.
// It uses a local implementation of holdForwardsStore to keep all the hold
// forwards and find them when manual resolution is later needed.
func (s *Server) HtlcInterceptor(stream Router_HtlcInterceptorServer) error {
// We ensure there is only one interceptor at a time.
if !atomic.CompareAndSwapInt32(&s.forwardInterceptorActive, 0, 1) {
return ErrInterceptorAlreadyExists
}
defer atomic.CompareAndSwapInt32(&s.forwardInterceptorActive, 1, 0)
// run the forward interceptor.
return newForwardInterceptor(s, stream).run()
}