package loop import ( "context" "crypto/tls" "encoding/hex" "errors" "fmt" "io" "net" "strings" "sync" "time" "github.com/btcsuite/btcd/btcec/v2" "github.com/btcsuite/btcd/btcutil" "github.com/lightninglabs/aperture/lsat" "github.com/lightninglabs/loop/loopdb" looprpc "github.com/lightninglabs/loop/swapserverrpc" "github.com/lightningnetwork/lnd/lnrpc" "github.com/lightningnetwork/lnd/lntypes" "github.com/lightningnetwork/lnd/routing/route" "github.com/lightningnetwork/lnd/tor" "github.com/lightningnetwork/lnd/zpay32" "google.golang.org/grpc" "google.golang.org/grpc/codes" "google.golang.org/grpc/credentials" "google.golang.org/grpc/status" ) var ( // errServerSubscriptionComplete is returned when our subscription to // server updates exits because the server has no more updates to // provide us, because its part in the swap is complete. errServerSubscriptionComplete = errors.New("server finished serving " + "updates") // errSubscriptionFailed is returned when our subscription returns with // and EOF, indicating that the server restarted, we had an unexpected // network failure. Since we do not have restart-recovery, we note that // we will not resume our subscription once this error occurs. errSubscriptionFailed = errors.New("failed, no further updates will " + "be provided") ) // RoutingPluginType represents the routing plugin type directly. type RoutingPluginType uint8 const ( // RoutingPluginNone is recommended when the client shouldn't use any // routing plugin. RoutingPluginNone RoutingPluginType = 0 // RoutingPluginLowHigh is recommended when the client should use // low-high routing method. RoutingPluginLowHigh RoutingPluginType = 1 ) // String pretty prints a RoutingPluginType. func (r RoutingPluginType) String() string { switch r { case RoutingPluginLowHigh: return "Low/High" default: return "None" } } type swapServerClient interface { GetLoopOutTerms(ctx context.Context, initiator string) ( *LoopOutTerms, error) GetLoopOutQuote(ctx context.Context, amt btcutil.Amount, expiry int32, swapPublicationDeadline time.Time, initiator string) ( *LoopOutQuote, error) GetLoopInTerms(ctx context.Context, initiator string) ( *LoopInTerms, error) GetLoopInQuote(ctx context.Context, amt btcutil.Amount, pubKey route.Vertex, lastHop *route.Vertex, routeHints [][]zpay32.HopHint, initiator string) (*LoopInQuote, error) Probe(ctx context.Context, amt btcutil.Amount, target route.Vertex, lastHop *route.Vertex, routeHints [][]zpay32.HopHint) error NewLoopOutSwap(ctx context.Context, swapHash lntypes.Hash, amount btcutil.Amount, expiry int32, receiverKey [33]byte, swapPublicationDeadline time.Time, initiator string) (*newLoopOutResponse, error) PushLoopOutPreimage(ctx context.Context, preimage lntypes.Preimage) error NewLoopInSwap(ctx context.Context, swapHash lntypes.Hash, amount btcutil.Amount, senderScriptKey, senderInternalKey [33]byte, swapInvoice, probeInvoice string, lastHop *route.Vertex, initiator string) ( *newLoopInResponse, error) // SubscribeLoopOutUpdates subscribes to loop out server state. SubscribeLoopOutUpdates(ctx context.Context, hash lntypes.Hash) (<-chan *ServerUpdate, <-chan error, error) // SubscribeLoopInUpdates subscribes to loop in server state. SubscribeLoopInUpdates(ctx context.Context, hash lntypes.Hash) (<-chan *ServerUpdate, <-chan error, error) // CancelLoopOutSwap cancels a loop out swap. CancelLoopOutSwap(ctx context.Context, details *outCancelDetails) error // RecommendRoutingPlugin asks the server for routing plugin // recommendation for off-chain payment(s) of a swap. RecommendRoutingPlugin(ctx context.Context, swapHash lntypes.Hash, paymentAddr [32]byte) (RoutingPluginType, error) // ReportRoutingResult reports a routing result corresponding to a swap. ReportRoutingResult(ctx context.Context, swapHash lntypes.Hash, paymentAddr [32]byte, plugin RoutingPluginType, success bool, attempts int32, totalTime int64) error // MuSig2SignSweep calls the server to cooperatively sign the MuSig2 // htlc spend. Returns the server's nonce and partial signature. MuSig2SignSweep(ctx context.Context, protocolVersion loopdb.ProtocolVersion, swapHash lntypes.Hash, paymentAddr [32]byte, nonce []byte, sweepTxPsbt []byte) ( []byte, []byte, error) // PushKey sends the client's HTLC internal key associated with the // swap to the server. PushKey(ctx context.Context, protocolVersion loopdb.ProtocolVersion, swapHash lntypes.Hash, clientInternalPrivateKey [32]byte) error } type grpcSwapServerClient struct { server looprpc.SwapServerClient conn *grpc.ClientConn wg sync.WaitGroup } // stop sends the signal for the server's goroutines to shutdown and waits for // them to complete. func (s *grpcSwapServerClient) stop() { if err := s.conn.Close(); err != nil { log.Warnf("could not close connection: %v", err) } s.wg.Wait() } var _ swapServerClient = (*grpcSwapServerClient)(nil) func newSwapServerClient(cfg *ClientConfig, lsatStore lsat.Store) ( *grpcSwapServerClient, error) { // Create the server connection with the interceptor that will handle // the LSAT protocol for us. clientInterceptor := lsat.NewInterceptor( cfg.Lnd, lsatStore, serverRPCTimeout, cfg.MaxLsatCost, cfg.MaxLsatFee, false, ) serverConn, err := getSwapServerConn( cfg.ServerAddress, cfg.ProxyAddress, cfg.SwapServerNoTLS, cfg.TLSPathServer, clientInterceptor, ) if err != nil { return nil, err } server := looprpc.NewSwapServerClient(serverConn) return &grpcSwapServerClient{ conn: serverConn, server: server, }, nil } func (s *grpcSwapServerClient) GetLoopOutTerms(ctx context.Context, initiator string) (*LoopOutTerms, error) { rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() terms, err := s.server.LoopOutTerms(rpcCtx, &looprpc.ServerLoopOutTermsRequest{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), UserAgent: UserAgent(initiator), }, ) if err != nil { return nil, err } return &LoopOutTerms{ MinSwapAmount: btcutil.Amount(terms.MinSwapAmount), MaxSwapAmount: btcutil.Amount(terms.MaxSwapAmount), MinCltvDelta: terms.MinCltvDelta, MaxCltvDelta: terms.MaxCltvDelta, }, nil } func (s *grpcSwapServerClient) GetLoopOutQuote(ctx context.Context, amt btcutil.Amount, expiry int32, swapPublicationDeadline time.Time, initiator string) (*LoopOutQuote, error) { rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() quoteResp, err := s.server.LoopOutQuote(rpcCtx, &looprpc.ServerLoopOutQuoteRequest{ Amt: uint64(amt), SwapPublicationDeadline: swapPublicationDeadline.Unix(), ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), Expiry: expiry, UserAgent: UserAgent(initiator), }, ) if err != nil { return nil, err } dest, err := hex.DecodeString(quoteResp.SwapPaymentDest) if err != nil { return nil, err } if len(dest) != 33 { return nil, errors.New("invalid payment dest") } var destArray [33]byte copy(destArray[:], dest) return &LoopOutQuote{ PrepayAmount: btcutil.Amount(quoteResp.PrepayAmt), SwapFee: btcutil.Amount(quoteResp.SwapFee), SwapPaymentDest: destArray, }, nil } func (s *grpcSwapServerClient) GetLoopInTerms(ctx context.Context, initiator string) (*LoopInTerms, error) { rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() terms, err := s.server.LoopInTerms(rpcCtx, &looprpc.ServerLoopInTermsRequest{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), UserAgent: UserAgent(initiator), }, ) if err != nil { return nil, err } return &LoopInTerms{ MinSwapAmount: btcutil.Amount(terms.MinSwapAmount), MaxSwapAmount: btcutil.Amount(terms.MaxSwapAmount), }, nil } func (s *grpcSwapServerClient) GetLoopInQuote(ctx context.Context, amt btcutil.Amount, pubKey route.Vertex, lastHop *route.Vertex, routeHints [][]zpay32.HopHint, initiator string) (*LoopInQuote, error) { err := s.Probe(ctx, amt, pubKey, lastHop, routeHints) if err != nil && status.Code(err) != codes.Unavailable { log.Warnf("Server probe error: %v", err) } rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() req := &looprpc.ServerLoopInQuoteRequest{ Amt: uint64(amt), ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), Pubkey: pubKey[:], UserAgent: UserAgent(initiator), } if lastHop != nil { req.LastHop = lastHop[:] } if routeHints != nil { rh, err := marshallRouteHints(routeHints) if err != nil { return nil, err } req.RouteHints = rh } quoteResp, err := s.server.LoopInQuote(rpcCtx, req) if err != nil { return nil, err } return &LoopInQuote{ SwapFee: btcutil.Amount(quoteResp.SwapFee), CltvDelta: quoteResp.CltvDelta, }, nil } // marshallRouteHints marshalls a list of route hints. func marshallRouteHints(routeHints [][]zpay32.HopHint) ( []*looprpc.RouteHint, error) { rpcRouteHints := make([]*looprpc.RouteHint, 0, len(routeHints)) for _, routeHint := range routeHints { rpcRouteHint := make( []*looprpc.HopHint, 0, len(routeHint), ) for _, hint := range routeHint { rpcHint, err := marshallHopHint(hint) if err != nil { return nil, err } rpcRouteHint = append(rpcRouteHint, rpcHint) } rpcRouteHints = append(rpcRouteHints, &looprpc.RouteHint{ HopHints: rpcRouteHint, }) } return rpcRouteHints, nil } // marshallHopHint marshalls a single hop hint. func marshallHopHint(hint zpay32.HopHint) (*looprpc.HopHint, error) { nodeID, err := route.NewVertexFromBytes( hint.NodeID.SerializeCompressed(), ) if err != nil { return nil, err } return &looprpc.HopHint{ ChanId: hint.ChannelID, CltvExpiryDelta: uint32(hint.CLTVExpiryDelta), FeeBaseMsat: hint.FeeBaseMSat, FeeProportionalMillionths: hint.FeeProportionalMillionths, NodeId: nodeID.String(), }, nil } func (s *grpcSwapServerClient) Probe(ctx context.Context, amt btcutil.Amount, target route.Vertex, lastHop *route.Vertex, routeHints [][]zpay32.HopHint) error { rpcCtx, rpcCancel := context.WithTimeout(ctx, probeTimeout) defer rpcCancel() rpcRouteHints, err := marshallRouteHints(routeHints) if err != nil { return err } req := &looprpc.ServerProbeRequest{ Amt: uint64(amt), Target: target[:], ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), RouteHints: rpcRouteHints, } if lastHop != nil { req.LastHop = lastHop[:] } _, err = s.server.Probe(rpcCtx, req) return err } func (s *grpcSwapServerClient) NewLoopOutSwap(ctx context.Context, swapHash lntypes.Hash, amount btcutil.Amount, expiry int32, receiverKey [33]byte, swapPublicationDeadline time.Time, initiator string) (*newLoopOutResponse, error) { rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() swapResp, err := s.server.NewLoopOutSwap(rpcCtx, &looprpc.ServerLoopOutRequest{ SwapHash: swapHash[:], Amt: uint64(amount), ReceiverKey: receiverKey[:], SwapPublicationDeadline: swapPublicationDeadline.Unix(), ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), Expiry: expiry, UserAgent: UserAgent(initiator), }, ) if err != nil { return nil, err } var senderKey [33]byte copy(senderKey[:], swapResp.SenderKey) // Validate sender key. _, err = btcec.ParsePubKey(senderKey[:]) if err != nil { return nil, fmt.Errorf("invalid sender key: %v", err) } return &newLoopOutResponse{ swapInvoice: swapResp.SwapInvoice, prepayInvoice: swapResp.PrepayInvoice, senderKey: senderKey, serverMessage: swapResp.ServerMessage, }, nil } // PushLoopOutPreimage pushes a preimage to the server. func (s *grpcSwapServerClient) PushLoopOutPreimage(ctx context.Context, preimage lntypes.Preimage) error { rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() _, err := s.server.LoopOutPushPreimage(rpcCtx, &looprpc.ServerLoopOutPushPreimageRequest{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), Preimage: preimage[:], }, ) return err } func (s *grpcSwapServerClient) NewLoopInSwap(ctx context.Context, swapHash lntypes.Hash, amount btcutil.Amount, senderScriptKey, senderInternalKey [33]byte, swapInvoice, probeInvoice string, lastHop *route.Vertex, initiator string) (*newLoopInResponse, error) { rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() req := &looprpc.ServerLoopInRequest{ SwapHash: swapHash[:], Amt: uint64(amount), SenderKey: senderScriptKey[:], SwapInvoice: swapInvoice, ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), ProbeInvoice: probeInvoice, UserAgent: UserAgent(initiator), } if lastHop != nil { req.LastHop = lastHop[:] } // Set the client's internal key if this is a MuSig2 swap. if loopdb.CurrentProtocolVersion() >= loopdb.ProtocolVersionMuSig2 { req.SenderInternalPubkey = senderInternalKey[:] } swapResp, err := s.server.NewLoopInSwap(rpcCtx, req) if err != nil { return nil, err } var receiverKey, receiverInternalKey [33]byte copy(receiverKey[:], swapResp.ReceiverKey) copy(receiverInternalKey[:], swapResp.ReceiverInternalPubkey) // Validate receiver key. _, err = btcec.ParsePubKey(receiverKey[:]) if err != nil { return nil, fmt.Errorf("invalid sender key: %v", err) } return &newLoopInResponse{ receiverKey: receiverKey, receiverInternalKey: receiverInternalKey, expiry: swapResp.Expiry, serverMessage: swapResp.ServerMessage, }, nil } // ServerUpdate summarizes an update from the swap server. type ServerUpdate struct { // State is the state that the server has sent us. State looprpc.ServerSwapState // Timestamp is the time of the server state update. Timestamp time.Time } // SubscribeLoopInUpdates subscribes to loop in server state and pipes updates // into the channel provided. func (s *grpcSwapServerClient) SubscribeLoopInUpdates(ctx context.Context, hash lntypes.Hash) (<-chan *ServerUpdate, <-chan error, error) { resp, err := s.server.SubscribeLoopInUpdates( ctx, &looprpc.SubscribeUpdatesRequest{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), SwapHash: hash[:], }, ) if err != nil { return nil, nil, err } receive := func() (*ServerUpdate, error) { response, err := resp.Recv() if err != nil { return nil, err } return &ServerUpdate{ State: response.State, Timestamp: time.Unix(0, response.TimestampNs), }, nil } updateChan, errChan := s.makeServerUpdate(ctx, receive) return updateChan, errChan, nil } // SubscribeLoopOutUpdates subscribes to loop out server state and pipes updates // into the channel provided. func (s *grpcSwapServerClient) SubscribeLoopOutUpdates(ctx context.Context, hash lntypes.Hash) (<-chan *ServerUpdate, <-chan error, error) { resp, err := s.server.SubscribeLoopOutUpdates( ctx, &looprpc.SubscribeUpdatesRequest{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), SwapHash: hash[:], }, ) if err != nil { return nil, nil, err } receive := func() (*ServerUpdate, error) { response, err := resp.Recv() if err != nil { return nil, err } return &ServerUpdate{ State: response.State, Timestamp: time.Unix(0, response.TimestampNs), }, nil } updateChan, errChan := s.makeServerUpdate(ctx, receive) return updateChan, errChan, nil } // makeServerUpdate takes a stream receive function and a channel that it // should pipe updates into. It sends events into the updates channel until // the client cancels, server client shuts down or the subscription is cancelled // server side. func (s *grpcSwapServerClient) makeServerUpdate(ctx context.Context, receive func() (*ServerUpdate, error)) (<-chan *ServerUpdate, <-chan error) { // We will return exactly one error from this function so we buffer // our error channel so that the function exit is not dependent on // the error being read. errChan := make(chan error, 1) updateChan := make(chan *ServerUpdate) // Create a goroutine that will pipe updates in to our updates channel. s.wg.Add(1) go func() { defer s.wg.Done() for { // Try to receive from our stream. If there are no items // to consume, this call will block. If our stream is // cancelled by the server we will receive an error. response, err := receive() switch err { // If we get a nil error, we proceed with to delivering // the update we have just received. case nil: // If we get an EOF error, the server is finished // sending us updates, so we return with a non-nil // a subscription complete error to inform the caller // that they will no longer receive updates. case io.EOF: errChan <- errServerSubscriptionComplete return // If we receive a non-nil error, we exit. default: // If we get a transport is closing error, we // send a server restarting error so that the // caller is informed that we will not get // any more updates from the server (since we // don't have retry logic yet). if isErrConClosing(err) { errChan <- errSubscriptionFailed } else { errChan <- err } return } select { // Try to send our update to the update channel. case updateChan <- response: // If the client cancels their context, we exit with // no error. case <-ctx.Done(): errChan <- nil return } } }() return updateChan, errChan } // paymentType is an enum representing different types of off-chain payments // made by a swap. type paymentType uint8 const ( // paymentTypePrepay indicates that we could not route the prepay. paymentTypePrepay paymentType = iota // paymentTypeInvoice indicates that we could not route the swap // invoice. paymentTypeInvoice ) // routeCancelMetadata contains cancelation information for swaps that are // canceled because the client could not route off-chain to the server. type routeCancelMetadata struct { // paymentType is the type of payment that failed. paymentType paymentType // attempts is the set of htlc attempts made by the client, reporting // the distance from the invoice's destination node that a failure // occurred. attempts []uint32 // failureReason is the reason that the payment failed. failureReason lnrpc.PaymentFailureReason } // outCancelDetails contains the informaton required to cancel a loop out swap. type outCancelDetails struct { // Hash is the swap's hash. hash lntypes.Hash // paymentAddr is the payment address for the swap's invoice. paymentAddr [32]byte // metadata contains additional information about the swap. metadata routeCancelMetadata } // CancelLoopOutSwap sends an instruction to the server to cancel a loop out // swap. func (s *grpcSwapServerClient) CancelLoopOutSwap(ctx context.Context, details *outCancelDetails) error { req := &looprpc.CancelLoopOutSwapRequest{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), SwapHash: details.hash[:], PaymentAddress: details.paymentAddr[:], } var err error req.CancelInfo, err = rpcRouteCancel(details) if err != nil { return err } _, err = s.server.CancelLoopOutSwap(ctx, req) return err } // RecommendRoutingPlugin asks the server for routing plugin recommendation for // off-chain payment(s) of a swap. func (s *grpcSwapServerClient) RecommendRoutingPlugin(ctx context.Context, swapHash lntypes.Hash, paymentAddr [32]byte) (RoutingPluginType, error) { req := &looprpc.RecommendRoutingPluginReq{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), SwapHash: swapHash[:], PaymentAddress: paymentAddr[:], } rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() res, err := s.server.RecommendRoutingPlugin(rpcCtx, req) if err != nil { return RoutingPluginNone, err } var plugin RoutingPluginType switch res.Plugin { case looprpc.RoutingPlugin_NONE: plugin = RoutingPluginNone case looprpc.RoutingPlugin_LOW_HIGH: plugin = RoutingPluginLowHigh default: log.Warnf("Recommended routing plugin is unknown: %v", plugin) plugin = RoutingPluginNone } return plugin, nil } // ReportRoutingResult reports a routing result corresponding to a swap. func (s *grpcSwapServerClient) ReportRoutingResult(ctx context.Context, swapHash lntypes.Hash, paymentAddr [32]byte, plugin RoutingPluginType, success bool, attempts int32, totalTime int64) error { var rpcRoutingPlugin looprpc.RoutingPlugin switch plugin { case RoutingPluginLowHigh: rpcRoutingPlugin = looprpc.RoutingPlugin_LOW_HIGH default: rpcRoutingPlugin = looprpc.RoutingPlugin_NONE } req := &looprpc.ReportRoutingResultReq{ ProtocolVersion: loopdb.CurrentRPCProtocolVersion(), SwapHash: swapHash[:], PaymentAddress: paymentAddr[:], Plugin: rpcRoutingPlugin, Success: success, Attempts: attempts, TotalTime: totalTime, } rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() _, err := s.server.ReportRoutingResult(rpcCtx, req) return err } // MuSig2SignSweep calls the server to cooperatively sign the MuSig2 htlc // spend. Returns the server's nonce and partial signature. func (s *grpcSwapServerClient) MuSig2SignSweep(ctx context.Context, protocolVersion loopdb.ProtocolVersion, swapHash lntypes.Hash, paymentAddr [32]byte, nonce []byte, sweepTxPsbt []byte) ( []byte, []byte, error) { req := &looprpc.MuSig2SignSweepReq{ ProtocolVersion: looprpc.ProtocolVersion(protocolVersion), SwapHash: swapHash[:], PaymentAddress: paymentAddr[:], Nonce: nonce, SweepTxPsbt: sweepTxPsbt, } rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() res, err := s.server.MuSig2SignSweep(rpcCtx, req) if err != nil { return nil, nil, err } return res.Nonce, res.PartialSignature, nil } // PushKey sends the client's HTLC internal key associated with the swap to // the server. func (s *grpcSwapServerClient) PushKey(ctx context.Context, protocolVersion loopdb.ProtocolVersion, swapHash lntypes.Hash, clientInternalPrivateKey [32]byte) error { req := &looprpc.ServerPushKeyReq{ ProtocolVersion: looprpc.ProtocolVersion(protocolVersion), SwapHash: swapHash[:], InternalPrivkey: clientInternalPrivateKey[:], } rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout) defer rpcCancel() _, err := s.server.PushKey(rpcCtx, req) return err } func rpcRouteCancel(details *outCancelDetails) ( *looprpc.CancelLoopOutSwapRequest_RouteCancel, error) { attempts := make( []*looprpc.HtlcAttempt, len(details.metadata.attempts), ) for i, remaining := range details.metadata.attempts { attempts[i] = &looprpc.HtlcAttempt{ RemainingHops: remaining, } } resp := &looprpc.CancelLoopOutSwapRequest_RouteCancel{ RouteCancel: &looprpc.RouteCancel{ Attempts: attempts, // We can cast our lnd failure reason to a loop payment // failure reason because these values are copied 1:1 // from lnd. Failure: looprpc.PaymentFailureReason( details.metadata.failureReason, ), }, } switch details.metadata.paymentType { case paymentTypePrepay: resp.RouteCancel.RouteType = looprpc.RoutePaymentType_PREPAY_ROUTE case paymentTypeInvoice: resp.RouteCancel.RouteType = looprpc.RoutePaymentType_INVOICE_ROUTE default: return nil, fmt.Errorf("unknown payment type: %v", details.metadata.paymentType) } return resp, nil } // getSwapServerConn returns a connection to the swap server. A non-empty // proxyAddr indicates that a SOCKS proxy found at the address should be used to // establish the connection. func getSwapServerConn(address, proxyAddress string, insecure bool, tlsPath string, interceptor *lsat.ClientInterceptor) (*grpc.ClientConn, error) { // Create a dial options array. opts := []grpc.DialOption{ grpc.WithUnaryInterceptor( interceptor.UnaryInterceptor, ), grpc.WithStreamInterceptor( interceptor.StreamInterceptor, ), } // There are three options to connect to a swap server, either insecure, // using a self-signed certificate or with a certificate signed by a // public CA. switch { case insecure: opts = append(opts, grpc.WithInsecure()) case tlsPath != "": // Load the specified TLS certificate and build // transport credentials creds, err := credentials.NewClientTLSFromFile(tlsPath, "") if err != nil { return nil, err } opts = append(opts, grpc.WithTransportCredentials(creds)) default: creds := credentials.NewTLS(&tls.Config{}) opts = append(opts, grpc.WithTransportCredentials(creds)) } // If a SOCKS proxy address was specified, then we should dial through // it. if proxyAddress != "" { log.Infof("Proxying connection to %v over Tor SOCKS proxy %v", address, proxyAddress) torDialer := func(_ context.Context, addr string) (net.Conn, error) { return tor.Dial( addr, proxyAddress, false, false, tor.DefaultConnTimeout, ) } opts = append(opts, grpc.WithContextDialer(torDialer)) } conn, err := grpc.Dial(address, opts...) if err != nil { return nil, fmt.Errorf("unable to connect to RPC server: %v", err) } return conn, nil } // isErrConClosing identifies whether we have received a "transport is closing" // error from a grpc stream, indicating that the server has shutdown. We need // to string match this error because ErrConnClosing is part of an internal // grpc package, so cannot be used directly. func isErrConClosing(err error) bool { if err == nil { return false } return strings.Contains(err.Error(), "transport is closing") } type newLoopOutResponse struct { swapInvoice string prepayInvoice string senderKey [33]byte serverMessage string } type newLoopInResponse struct { receiverKey [33]byte receiverInternalKey [33]byte expiry int32 serverMessage string }