package loopd import ( "context" "encoding/hex" "errors" "fmt" "sort" "sync" "time" "github.com/btcsuite/btcd/btcec/v2" "github.com/btcsuite/btcd/btcutil" "github.com/btcsuite/btcd/chaincfg" "github.com/lightninglabs/lndclient" "github.com/lightninglabs/loop" "github.com/lightninglabs/loop/labels" "github.com/lightninglabs/loop/liquidity" "github.com/lightninglabs/loop/loopdb" clientrpc "github.com/lightninglabs/loop/looprpc" "github.com/lightninglabs/loop/swap" looprpc "github.com/lightninglabs/loop/swapserverrpc" "github.com/lightningnetwork/lnd/lntypes" "github.com/lightningnetwork/lnd/queue" "github.com/lightningnetwork/lnd/routing/route" "github.com/lightningnetwork/lnd/zpay32" "google.golang.org/grpc/codes" "google.golang.org/grpc/status" ) const ( completedSwapsCount = 5 // minConfTarget is the minimum confirmation target we'll allow clients // to specify. This is driven by the minimum confirmation target allowed // by the backing fee estimator. minConfTarget = 2 ) var ( // errIncorrectChain is returned when the format of the // destination address provided does not match the active chain. errIncorrectChain = errors.New("invalid address format for the " + "active chain") // errConfTargetTooLow is returned when the chosen confirmation target // is below the allowed minimum. errConfTargetTooLow = errors.New("confirmation target too low") // errBalanceTooLow is returned when the loop out amount can't be // satisfied given total balance of the selection of channels to loop // out on. errBalanceTooLow = errors.New( "channel balance too low for loop out amount", ) // errInvalidAddress is returned when the destination address is of // an unsupported format such as P2PK or P2TR addresses. errInvalidAddress = errors.New( "invalid or unsupported address", ) ) // swapClientServer implements the grpc service exposed by loopd. type swapClientServer struct { // Required by the grpc-gateway/v2 library for forward compatibility. clientrpc.UnimplementedSwapClientServer clientrpc.UnimplementedDebugServer network lndclient.Network impl *loop.Client liquidityMgr *liquidity.Manager lnd *lndclient.LndServices swaps map[lntypes.Hash]loop.SwapInfo subscribers map[int]chan<- interface{} statusChan chan loop.SwapInfo nextSubscriberID int swapsLock sync.Mutex mainCtx context.Context } // LoopOut initiates an loop out swap with the given parameters. The call // returns after the swap has been set up with the swap server. From that point // onwards, progress can be tracked via the LoopOutStatus stream that is // returned from Monitor(). func (s *swapClientServer) LoopOut(ctx context.Context, in *clientrpc.LoopOutRequest) ( *clientrpc.SwapResponse, error) { log.Infof("Loop out request received") var sweepAddr btcutil.Address if in.Dest == "" { // Generate sweep address if none specified. var err error sweepAddr, err = s.lnd.WalletKit.NextAddr(context.Background()) if err != nil { return nil, fmt.Errorf("NextAddr error: %v", err) } } else { var err error sweepAddr, err = btcutil.DecodeAddress( in.Dest, s.lnd.ChainParams, ) if err != nil { return nil, fmt.Errorf("decode address: %v", err) } } sweepConfTarget, err := validateLoopOutRequest( ctx, s.lnd.Client, s.lnd.ChainParams, in, sweepAddr, s.impl.LoopOutMaxParts, ) if err != nil { return nil, err } req := &loop.OutRequest{ Amount: btcutil.Amount(in.Amt), DestAddr: sweepAddr, MaxMinerFee: btcutil.Amount(in.MaxMinerFee), MaxPrepayAmount: btcutil.Amount(in.MaxPrepayAmt), MaxPrepayRoutingFee: btcutil.Amount(in.MaxPrepayRoutingFee), MaxSwapRoutingFee: btcutil.Amount(in.MaxSwapRoutingFee), MaxSwapFee: btcutil.Amount(in.MaxSwapFee), SweepConfTarget: sweepConfTarget, HtlcConfirmations: in.HtlcConfirmations, SwapPublicationDeadline: time.Unix( int64(in.SwapPublicationDeadline), 0, ), Label: in.Label, Initiator: in.Initiator, } switch { case in.LoopOutChannel != 0 && len(in.OutgoingChanSet) > 0: // nolint:staticcheck return nil, errors.New("loop_out_channel and outgoing_" + "chan_ids are mutually exclusive") case in.LoopOutChannel != 0: // nolint:staticcheck req.OutgoingChanSet = loopdb.ChannelSet{in.LoopOutChannel} // nolint:staticcheck default: req.OutgoingChanSet = in.OutgoingChanSet } info, err := s.impl.LoopOut(ctx, req) if err != nil { log.Errorf("LoopOut: %v", err) return nil, err } return &clientrpc.SwapResponse{ Id: info.SwapHash.String(), IdBytes: info.SwapHash[:], HtlcAddress: info.HtlcAddressP2WSH.String(), HtlcAddressP2Wsh: info.HtlcAddressP2WSH.String(), ServerMessage: info.ServerMessage, }, nil } func (s *swapClientServer) marshallSwap(loopSwap *loop.SwapInfo) ( *clientrpc.SwapStatus, error) { var ( state clientrpc.SwapState failureReason = clientrpc.FailureReason_FAILURE_REASON_NONE ) // Set our state var for non-failure states. If we get a failure, we // will update our failure reason. To remain backwards compatible with // previous versions where we squashed all failure reasons to a single // failure state, we set a failure reason for all our different failure // states, and set our failed state for all of them. switch loopSwap.State { case loopdb.StateInitiated: state = clientrpc.SwapState_INITIATED case loopdb.StatePreimageRevealed: state = clientrpc.SwapState_PREIMAGE_REVEALED case loopdb.StateHtlcPublished: state = clientrpc.SwapState_HTLC_PUBLISHED case loopdb.StateInvoiceSettled: state = clientrpc.SwapState_INVOICE_SETTLED case loopdb.StateSuccess: state = clientrpc.SwapState_SUCCESS case loopdb.StateFailOffchainPayments: failureReason = clientrpc.FailureReason_FAILURE_REASON_OFFCHAIN case loopdb.StateFailTimeout: failureReason = clientrpc.FailureReason_FAILURE_REASON_TIMEOUT case loopdb.StateFailSweepTimeout: failureReason = clientrpc.FailureReason_FAILURE_REASON_SWEEP_TIMEOUT case loopdb.StateFailInsufficientValue: failureReason = clientrpc.FailureReason_FAILURE_REASON_INSUFFICIENT_VALUE case loopdb.StateFailTemporary: failureReason = clientrpc.FailureReason_FAILURE_REASON_TEMPORARY case loopdb.StateFailIncorrectHtlcAmt: failureReason = clientrpc.FailureReason_FAILURE_REASON_INCORRECT_AMOUNT default: return nil, fmt.Errorf("unknown swap state: %v", loopSwap.State) } // If we have a failure reason, we have a failure state, so should use // our catchall failed state. if failureReason != clientrpc.FailureReason_FAILURE_REASON_NONE { state = clientrpc.SwapState_FAILED } var swapType clientrpc.SwapType var htlcAddress, htlcAddressP2WSH, htlcAddressNP2WSH string var outGoingChanSet []uint64 var lastHop []byte switch loopSwap.SwapType { case swap.TypeIn: swapType = clientrpc.SwapType_LOOP_IN htlcAddressP2WSH = loopSwap.HtlcAddressP2WSH.EncodeAddress() if loopSwap.ExternalHtlc { htlcAddressNP2WSH = loopSwap.HtlcAddressNP2WSH.EncodeAddress() htlcAddress = htlcAddressNP2WSH } else { htlcAddress = htlcAddressP2WSH } if loopSwap.LastHop != nil { lastHop = loopSwap.LastHop[:] } case swap.TypeOut: swapType = clientrpc.SwapType_LOOP_OUT htlcAddressP2WSH = loopSwap.HtlcAddressP2WSH.EncodeAddress() htlcAddress = htlcAddressP2WSH outGoingChanSet = loopSwap.OutgoingChanSet default: return nil, errors.New("unknown swap type") } return &clientrpc.SwapStatus{ Amt: int64(loopSwap.AmountRequested), Id: loopSwap.SwapHash.String(), IdBytes: loopSwap.SwapHash[:], State: state, FailureReason: failureReason, InitiationTime: loopSwap.InitiationTime.UnixNano(), LastUpdateTime: loopSwap.LastUpdate.UnixNano(), HtlcAddress: htlcAddress, HtlcAddressP2Wsh: htlcAddressP2WSH, HtlcAddressNp2Wsh: htlcAddressNP2WSH, Type: swapType, CostServer: int64(loopSwap.Cost.Server), CostOnchain: int64(loopSwap.Cost.Onchain), CostOffchain: int64(loopSwap.Cost.Offchain), Label: loopSwap.Label, LastHop: lastHop, OutgoingChanSet: outGoingChanSet, }, nil } // Monitor will return a stream of swap updates for currently active swaps. func (s *swapClientServer) Monitor(in *clientrpc.MonitorRequest, server clientrpc.SwapClient_MonitorServer) error { log.Infof("Monitor request received") send := func(info loop.SwapInfo) error { rpcSwap, err := s.marshallSwap(&info) if err != nil { return err } return server.Send(rpcSwap) } // Start a notification queue for this subscriber. queue := queue.NewConcurrentQueue(20) queue.Start() // Add this subscriber to the global subscriber list. Also create a // snapshot of all pending and completed swaps within the lock, to // prevent subscribers from receiving duplicate updates. s.swapsLock.Lock() id := s.nextSubscriberID s.nextSubscriberID++ s.subscribers[id] = queue.ChanIn() var pendingSwaps, completedSwaps []loop.SwapInfo for _, swap := range s.swaps { if swap.State.Type() == loopdb.StateTypePending { pendingSwaps = append(pendingSwaps, swap) } else { completedSwaps = append(completedSwaps, swap) } } s.swapsLock.Unlock() defer func() { s.swapsLock.Lock() delete(s.subscribers, id) s.swapsLock.Unlock() queue.Stop() }() // Sort completed swaps new to old. sort.Slice(completedSwaps, func(i, j int) bool { return completedSwaps[i].LastUpdate.After( completedSwaps[j].LastUpdate, ) }) // Discard all but top x latest. if len(completedSwaps) > completedSwapsCount { completedSwaps = completedSwaps[:completedSwapsCount] } // Concatenate both sets. filteredSwaps := append(pendingSwaps, completedSwaps...) // nolint: gocritic // Sort again, but this time old to new. sort.Slice(filteredSwaps, func(i, j int) bool { return filteredSwaps[i].LastUpdate.Before( filteredSwaps[j].LastUpdate, ) }) // Return swaps to caller. for _, swap := range filteredSwaps { if err := send(swap); err != nil { return err } } // As long as the client is connected, keep passing through swap // updates. for { select { case queueItem, ok := <-queue.ChanOut(): if !ok { return nil } swap := queueItem.(loop.SwapInfo) if err := send(swap); err != nil { return err } // The client cancels the subscription. case <-server.Context().Done(): return nil // The server is shutting down. case <-s.mainCtx.Done(): return fmt.Errorf("server is shutting down") } } } // ListSwaps returns a list of all currently known swaps and their current // status. func (s *swapClientServer) ListSwaps(_ context.Context, _ *clientrpc.ListSwapsRequest) (*clientrpc.ListSwapsResponse, error) { var ( rpcSwaps = make([]*clientrpc.SwapStatus, len(s.swaps)) idx = 0 err error ) s.swapsLock.Lock() defer s.swapsLock.Unlock() // We can just use the server's in-memory cache as that contains the // most up-to-date state including temporary failures which aren't // persisted to disk. The swaps field is a map, that's why we need an // additional index. for _, swp := range s.swaps { swp := swp rpcSwaps[idx], err = s.marshallSwap(&swp) if err != nil { return nil, err } idx++ } return &clientrpc.ListSwapsResponse{Swaps: rpcSwaps}, nil } // SwapInfo returns all known details about a single swap. func (s *swapClientServer) SwapInfo(_ context.Context, req *clientrpc.SwapInfoRequest) (*clientrpc.SwapStatus, error) { swapHash, err := lntypes.MakeHash(req.Id) if err != nil { return nil, fmt.Errorf("error parsing swap hash: %v", err) } // Just return the server's in-memory cache here too as we also want to // return temporary failures to the client. swp, ok := s.swaps[swapHash] if !ok { return nil, fmt.Errorf("swap with hash %s not found", req.Id) } return s.marshallSwap(&swp) } // LoopOutTerms returns the terms that the server enforces for loop out swaps. func (s *swapClientServer) LoopOutTerms(ctx context.Context, req *clientrpc.TermsRequest) (*clientrpc.OutTermsResponse, error) { log.Infof("Loop out terms request received") terms, err := s.impl.LoopOutTerms(ctx) if err != nil { log.Errorf("Terms request: %v", err) return nil, err } return &clientrpc.OutTermsResponse{ MinSwapAmount: int64(terms.MinSwapAmount), MaxSwapAmount: int64(terms.MaxSwapAmount), MinCltvDelta: terms.MinCltvDelta, MaxCltvDelta: terms.MaxCltvDelta, }, nil } // LoopOutQuote returns a quote for a loop out swap with the provided // parameters. func (s *swapClientServer) LoopOutQuote(ctx context.Context, req *clientrpc.QuoteRequest) (*clientrpc.OutQuoteResponse, error) { confTarget, err := validateConfTarget( req.ConfTarget, loop.DefaultSweepConfTarget, ) if err != nil { return nil, err } quote, err := s.impl.LoopOutQuote(ctx, &loop.LoopOutQuoteRequest{ Amount: btcutil.Amount(req.Amt), SweepConfTarget: confTarget, SwapPublicationDeadline: time.Unix( int64(req.SwapPublicationDeadline), 0, ), }) if err != nil { return nil, err } return &clientrpc.OutQuoteResponse{ HtlcSweepFeeSat: int64(quote.MinerFee), PrepayAmtSat: int64(quote.PrepayAmount), SwapFeeSat: int64(quote.SwapFee), SwapPaymentDest: quote.SwapPaymentDest[:], ConfTarget: confTarget, }, nil } // GetTerms returns the terms that the server enforces for swaps. func (s *swapClientServer) GetLoopInTerms(ctx context.Context, req *clientrpc.TermsRequest) (*clientrpc.InTermsResponse, error) { log.Infof("Loop in terms request received") terms, err := s.impl.LoopInTerms(ctx) if err != nil { log.Errorf("Terms request: %v", err) return nil, err } return &clientrpc.InTermsResponse{ MinSwapAmount: int64(terms.MinSwapAmount), MaxSwapAmount: int64(terms.MaxSwapAmount), }, nil } // GetQuote returns a quote for a swap with the provided parameters. func (s *swapClientServer) GetLoopInQuote(ctx context.Context, req *clientrpc.QuoteRequest) (*clientrpc.InQuoteResponse, error) { log.Infof("Loop in quote request received") htlcConfTarget, err := validateLoopInRequest( req.ConfTarget, req.ExternalHtlc, ) if err != nil { return nil, err } var ( routeHints [][]zpay32.HopHint lastHop *route.Vertex ) if req.LoopInLastHop != nil { lastHopVertex, err := route.NewVertexFromBytes( req.LoopInLastHop, ) if err != nil { return nil, err } lastHop = &lastHopVertex } if len(req.LoopInRouteHints) != 0 { routeHints, err = unmarshallRouteHints(req.LoopInRouteHints) if err != nil { return nil, err } } quote, err := s.impl.LoopInQuote(ctx, &loop.LoopInQuoteRequest{ Amount: btcutil.Amount(req.Amt), HtlcConfTarget: htlcConfTarget, ExternalHtlc: req.ExternalHtlc, LastHop: lastHop, RouteHints: routeHints, Private: req.Private, }) if err != nil { return nil, err } return &clientrpc.InQuoteResponse{ HtlcPublishFeeSat: int64(quote.MinerFee), SwapFeeSat: int64(quote.SwapFee), ConfTarget: htlcConfTarget, }, nil } // unmarshallRouteHints unmarshalls a list of route hints. func unmarshallRouteHints(rpcRouteHints []*looprpc.RouteHint) ( [][]zpay32.HopHint, error) { routeHints := make([][]zpay32.HopHint, 0, len(rpcRouteHints)) for _, rpcRouteHint := range rpcRouteHints { routeHint := make( []zpay32.HopHint, 0, len(rpcRouteHint.HopHints), ) for _, rpcHint := range rpcRouteHint.HopHints { hint, err := unmarshallHopHint(rpcHint) if err != nil { return nil, err } routeHint = append(routeHint, hint) } routeHints = append(routeHints, routeHint) } return routeHints, nil } // unmarshallHopHint unmarshalls a single hop hint. func unmarshallHopHint(rpcHint *looprpc.HopHint) (zpay32.HopHint, error) { pubBytes, err := hex.DecodeString(rpcHint.NodeId) if err != nil { return zpay32.HopHint{}, err } pubkey, err := btcec.ParsePubKey(pubBytes) if err != nil { return zpay32.HopHint{}, err } return zpay32.HopHint{ NodeID: pubkey, ChannelID: rpcHint.ChanId, FeeBaseMSat: rpcHint.FeeBaseMsat, FeeProportionalMillionths: rpcHint.FeeProportionalMillionths, CLTVExpiryDelta: uint16(rpcHint.CltvExpiryDelta), }, nil } // Probe requests the server to probe the client's node to test inbound // liquidity. func (s *swapClientServer) Probe(ctx context.Context, req *clientrpc.ProbeRequest) (*clientrpc.ProbeResponse, error) { log.Infof("Probe request received") var lastHop *route.Vertex if req.LastHop != nil { lastHopVertex, err := route.NewVertexFromBytes(req.LastHop) if err != nil { return nil, err } lastHop = &lastHopVertex } routeHints, err := unmarshallRouteHints(req.RouteHints) if err != nil { return nil, err } err = s.impl.Probe(ctx, &loop.ProbeRequest{ Amount: btcutil.Amount(req.Amt), LastHop: lastHop, RouteHints: routeHints, }) if err != nil { return nil, err } return &clientrpc.ProbeResponse{}, nil } func (s *swapClientServer) LoopIn(ctx context.Context, in *clientrpc.LoopInRequest) ( *clientrpc.SwapResponse, error) { log.Infof("Loop in request received") htlcConfTarget, err := validateLoopInRequest( in.HtlcConfTarget, in.ExternalHtlc, ) if err != nil { return nil, err } // Check that the label is valid. if err := labels.Validate(in.Label); err != nil { return nil, err } routeHints, err := unmarshallRouteHints(in.RouteHints) if err != nil { return nil, err } req := &loop.LoopInRequest{ Amount: btcutil.Amount(in.Amt), MaxMinerFee: btcutil.Amount(in.MaxMinerFee), MaxSwapFee: btcutil.Amount(in.MaxSwapFee), HtlcConfTarget: htlcConfTarget, ExternalHtlc: in.ExternalHtlc, Label: in.Label, Initiator: in.Initiator, Private: in.Private, RouteHints: routeHints, } if in.LastHop != nil { lastHop, err := route.NewVertexFromBytes(in.LastHop) if err != nil { return nil, err } req.LastHop = &lastHop } swapInfo, err := s.impl.LoopIn(ctx, req) if err != nil { log.Errorf("Loop in: %v", err) return nil, err } response := &clientrpc.SwapResponse{ Id: swapInfo.SwapHash.String(), IdBytes: swapInfo.SwapHash[:], HtlcAddressP2Wsh: swapInfo.HtlcAddressP2WSH.String(), ServerMessage: swapInfo.ServerMessage, } if req.ExternalHtlc { response.HtlcAddressNp2Wsh = swapInfo.HtlcAddressNP2WSH.String() response.HtlcAddress = response.HtlcAddressNp2Wsh // nolint:staticcheck } else { response.HtlcAddress = response.HtlcAddressP2Wsh // nolint:staticcheck } return response, nil } // GetLsatTokens returns all tokens that are contained in the LSAT token store. func (s *swapClientServer) GetLsatTokens(ctx context.Context, _ *clientrpc.TokensRequest) (*clientrpc.TokensResponse, error) { log.Infof("Get LSAT tokens request received") tokens, err := s.impl.LsatStore.AllTokens() if err != nil { return nil, err } rpcTokens := make([]*clientrpc.LsatToken, len(tokens)) idx := 0 for key, token := range tokens { macBytes, err := token.BaseMacaroon().MarshalBinary() if err != nil { return nil, err } rpcTokens[idx] = &clientrpc.LsatToken{ BaseMacaroon: macBytes, PaymentHash: token.PaymentHash[:], PaymentPreimage: token.Preimage[:], AmountPaidMsat: int64(token.AmountPaid), RoutingFeePaidMsat: int64(token.RoutingFeePaid), TimeCreated: token.TimeCreated.Unix(), Expired: !token.IsValid(), StorageName: key, } idx++ } return &clientrpc.TokensResponse{Tokens: rpcTokens}, nil } // GetLiquidityParams gets our current liquidity manager's parameters. func (s *swapClientServer) GetLiquidityParams(_ context.Context, _ *clientrpc.GetLiquidityParamsRequest) (*clientrpc.LiquidityParameters, error) { cfg := s.liquidityMgr.GetParameters() totalRules := len(cfg.ChannelRules) + len(cfg.PeerRules) rpcCfg := &clientrpc.LiquidityParameters{ SweepConfTarget: cfg.SweepConfTarget, FailureBackoffSec: uint64(cfg.FailureBackOff.Seconds()), Autoloop: cfg.Autoloop, AutoloopBudgetSat: uint64(cfg.AutoFeeBudget), AutoMaxInFlight: uint64(cfg.MaxAutoInFlight), Rules: make( []*clientrpc.LiquidityRule, 0, totalRules, ), MinSwapAmount: uint64(cfg.ClientRestrictions.Minimum), MaxSwapAmount: uint64(cfg.ClientRestrictions.Maximum), HtlcConfTarget: cfg.HtlcConfTarget, } switch f := cfg.FeeLimit.(type) { case *liquidity.FeeCategoryLimit: satPerByte := f.SweepFeeRateLimit.FeePerKVByte() / 1000 rpcCfg.SweepFeeRateSatPerVbyte = uint64(satPerByte) rpcCfg.MaxMinerFeeSat = uint64(f.MaximumMinerFee) rpcCfg.MaxSwapFeePpm = f.MaximumSwapFeePPM rpcCfg.MaxRoutingFeePpm = f.MaximumRoutingFeePPM rpcCfg.MaxPrepayRoutingFeePpm = f.MaximumPrepayRoutingFeePPM rpcCfg.MaxPrepaySat = uint64(f.MaximumPrepay) case *liquidity.FeePortion: rpcCfg.FeePpm = f.PartsPerMillion default: return nil, fmt.Errorf("unknown fee limit: %T", cfg.FeeLimit) } // Zero golang time is different to a zero unix time, so we only set // our start date if it is non-zero. if !cfg.AutoFeeStartDate.IsZero() { rpcCfg.AutoloopBudgetStartSec = uint64( cfg.AutoFeeStartDate.Unix(), ) } for channel, rule := range cfg.ChannelRules { rpcRule := newRPCRule(channel.ToUint64(), nil, rule) rpcCfg.Rules = append(rpcCfg.Rules, rpcRule) } for peer, rule := range cfg.PeerRules { peer := peer rpcRule := newRPCRule(0, peer[:], rule) rpcCfg.Rules = append(rpcCfg.Rules, rpcRule) } return rpcCfg, nil } func newRPCRule(channelID uint64, peer []byte, rule *liquidity.SwapRule) *clientrpc.LiquidityRule { rpcRule := &clientrpc.LiquidityRule{ ChannelId: channelID, Pubkey: peer, Type: clientrpc.LiquidityRuleType_THRESHOLD, IncomingThreshold: uint32(rule.MinimumIncoming), OutgoingThreshold: uint32(rule.MinimumOutgoing), SwapType: clientrpc.SwapType_LOOP_OUT, } if rule.Type == swap.TypeIn { rpcRule.SwapType = clientrpc.SwapType_LOOP_IN } return rpcRule } // SetLiquidityParams attempts to set our current liquidity manager's // parameters. func (s *swapClientServer) SetLiquidityParams(ctx context.Context, in *clientrpc.SetLiquidityParamsRequest) (*clientrpc.SetLiquidityParamsResponse, error) { err := s.liquidityMgr.SetParameters(ctx, in.Parameters) if err != nil { return nil, err } return &clientrpc.SetLiquidityParamsResponse{}, nil } // SuggestSwaps provides a list of suggested swaps based on lnd's current // channel balances and rules set by the liquidity manager. func (s *swapClientServer) SuggestSwaps(ctx context.Context, _ *clientrpc.SuggestSwapsRequest) (*clientrpc.SuggestSwapsResponse, error) { suggestions, err := s.liquidityMgr.SuggestSwaps(ctx, false) switch err { case liquidity.ErrNoRules: return nil, status.Error(codes.FailedPrecondition, err.Error()) case nil: default: return nil, err } resp := &clientrpc.SuggestSwapsResponse{ LoopOut: make( []*clientrpc.LoopOutRequest, len(suggestions.OutSwaps), ), LoopIn: make( []*clientrpc.LoopInRequest, len(suggestions.InSwaps), ), } for i, swap := range suggestions.OutSwaps { resp.LoopOut[i] = &clientrpc.LoopOutRequest{ Amt: int64(swap.Amount), OutgoingChanSet: swap.OutgoingChanSet, MaxSwapFee: int64(swap.MaxSwapFee), MaxMinerFee: int64(swap.MaxMinerFee), MaxPrepayAmt: int64(swap.MaxPrepayAmount), MaxSwapRoutingFee: int64(swap.MaxSwapRoutingFee), MaxPrepayRoutingFee: int64(swap.MaxPrepayRoutingFee), SweepConfTarget: swap.SweepConfTarget, } } for i, swap := range suggestions.InSwaps { loopIn := &clientrpc.LoopInRequest{ Amt: int64(swap.Amount), MaxSwapFee: int64(swap.MaxSwapFee), MaxMinerFee: int64(swap.MaxMinerFee), HtlcConfTarget: swap.HtlcConfTarget, } if swap.LastHop != nil { loopIn.LastHop = swap.LastHop[:] } resp.LoopIn[i] = loopIn } for id, reason := range suggestions.DisqualifiedChans { autoloopReason, err := rpcAutoloopReason(reason) if err != nil { return nil, err } exclChan := &clientrpc.Disqualified{ Reason: autoloopReason, ChannelId: id.ToUint64(), } resp.Disqualified = append(resp.Disqualified, exclChan) } for pubkey, reason := range suggestions.DisqualifiedPeers { autoloopReason, err := rpcAutoloopReason(reason) if err != nil { return nil, err } exclChan := &clientrpc.Disqualified{ Reason: autoloopReason, Pubkey: pubkey[:], } resp.Disqualified = append(resp.Disqualified, exclChan) } return resp, nil } func rpcAutoloopReason(reason liquidity.Reason) (clientrpc.AutoReason, error) { switch reason { case liquidity.ReasonNone: return clientrpc.AutoReason_AUTO_REASON_UNKNOWN, nil case liquidity.ReasonBudgetNotStarted: return clientrpc.AutoReason_AUTO_REASON_BUDGET_NOT_STARTED, nil case liquidity.ReasonSweepFees: return clientrpc.AutoReason_AUTO_REASON_SWEEP_FEES, nil case liquidity.ReasonBudgetElapsed: return clientrpc.AutoReason_AUTO_REASON_BUDGET_ELAPSED, nil case liquidity.ReasonInFlight: return clientrpc.AutoReason_AUTO_REASON_IN_FLIGHT, nil case liquidity.ReasonSwapFee: return clientrpc.AutoReason_AUTO_REASON_SWAP_FEE, nil case liquidity.ReasonMinerFee: return clientrpc.AutoReason_AUTO_REASON_MINER_FEE, nil case liquidity.ReasonPrepay: return clientrpc.AutoReason_AUTO_REASON_PREPAY, nil case liquidity.ReasonFailureBackoff: return clientrpc.AutoReason_AUTO_REASON_FAILURE_BACKOFF, nil case liquidity.ReasonLoopOut: return clientrpc.AutoReason_AUTO_REASON_LOOP_OUT, nil case liquidity.ReasonLoopIn: return clientrpc.AutoReason_AUTO_REASON_LOOP_IN, nil case liquidity.ReasonLiquidityOk: return clientrpc.AutoReason_AUTO_REASON_LIQUIDITY_OK, nil case liquidity.ReasonBudgetInsufficient: return clientrpc.AutoReason_AUTO_REASON_BUDGET_INSUFFICIENT, nil case liquidity.ReasonFeePPMInsufficient: return clientrpc.AutoReason_AUTO_REASON_SWAP_FEE, nil default: return 0, fmt.Errorf("unknown autoloop reason: %v", reason) } } // processStatusUpdates reads updates on the status channel and processes them. // // NOTE: This must run inside a goroutine as it blocks until the main context // shuts down. func (s *swapClientServer) processStatusUpdates(mainCtx context.Context) { for { select { // On updates, refresh the server's in-memory state and inform // subscribers about the changes. case swp := <-s.statusChan: s.swapsLock.Lock() s.swaps[swp.SwapHash] = swp for _, subscriber := range s.subscribers { select { case subscriber <- swp: case <-mainCtx.Done(): s.swapsLock.Unlock() return } } s.swapsLock.Unlock() // Server is shutting down. case <-mainCtx.Done(): return } } } // validateConfTarget ensures the given confirmation target is valid. If one // isn't specified (0 value), then the default target is used. func validateConfTarget(target, defaultTarget int32) (int32, error) { switch { case target == 0: return defaultTarget, nil // Ensure the target respects our minimum threshold. case target < minConfTarget: return 0, fmt.Errorf("%w: A confirmation target of at "+ "least %v must be provided", errConfTargetTooLow, minConfTarget) default: return target, nil } } // validateLoopInRequest fails if the mutually exclusive conf target and // external parameters are both set. func validateLoopInRequest(htlcConfTarget int32, external bool) (int32, error) { // If the htlc is going to be externally set, the htlcConfTarget should // not be set, because it has no relevance when the htlc is external. if external && htlcConfTarget != 0 { return 0, errors.New("external and htlc conf target cannot " + "both be set") } // If the htlc is being externally published, we do not need to set a // confirmation target. if external { return 0, nil } return validateConfTarget(htlcConfTarget, loop.DefaultHtlcConfTarget) } // validateLoopOutRequest validates the confirmation target, destination // address and label of the loop out request. It also checks that the requested // loop amount is valid given the available balance. func validateLoopOutRequest(ctx context.Context, lnd lndclient.LightningClient, chainParams *chaincfg.Params, req *clientrpc.LoopOutRequest, sweepAddr btcutil.Address, maxParts uint32) (int32, error) { // Check that the provided destination address has the correct format // for the active network. if !sweepAddr.IsForNet(chainParams) { return 0, fmt.Errorf("%w: Current active network is %s", errIncorrectChain, chainParams.Name) } // Check that the provided destination address is a supported // address format. switch sweepAddr.(type) { case *btcutil.AddressWitnessScriptHash, *btcutil.AddressWitnessPubKeyHash, *btcutil.AddressScriptHash, *btcutil.AddressPubKeyHash: default: return 0, errInvalidAddress } // Check that the label is valid. if err := labels.Validate(req.Label); err != nil { return 0, err } channels, err := lnd.ListChannels(ctx, false, false) if err != nil { return 0, err } unlimitedChannels := len(req.OutgoingChanSet) == 0 outgoingChanSetMap := make(map[uint64]bool) for _, chanID := range req.OutgoingChanSet { outgoingChanSetMap[chanID] = true } var activeChannelSet []lndclient.ChannelInfo for _, c := range channels { // Don't bother looking at inactive channels. if !c.Active { continue } // If no outgoing channel set was specified then all active // channels are considered. However, if a channel set was // specified then only the specified channels are considered. if unlimitedChannels || outgoingChanSetMap[c.ChannelID] { activeChannelSet = append(activeChannelSet, c) } } // Determine if the loop out request is theoretically possible given // the amount requested, the maximum possible routing fees, // the available channel set and the fact that equal splitting is // used for MPP. requiredBalance := btcutil.Amount(req.Amt + req.MaxSwapRoutingFee) isRoutable, _ := hasBandwidth(activeChannelSet, requiredBalance, int(maxParts)) if !isRoutable { return 0, fmt.Errorf("%w: Requested swap amount of %d "+ "sats along with the maximum routing fee of %d sats "+ "is more than what can be routed given current state "+ "of the channel set", errBalanceTooLow, req.Amt, req.MaxSwapRoutingFee) } return validateConfTarget( req.SweepConfTarget, loop.DefaultSweepConfTarget, ) } // hasBandwidth simulates the MPP splitting logic that will be used by LND when // attempting to route the payment. This function is used to evaluate if a // payment will be routable given the splitting logic used by LND. // It returns true if the amount is routable given the channel set and the // maximum number of shards allowed. If the amount is routable then the number // of shards used is also returned. This function makes an assumption that the // minimum loop amount divided by max parts will not be less than the minimum // shard amount. If the MPP logic changes, then this function should be updated. func hasBandwidth(channels []lndclient.ChannelInfo, amt btcutil.Amount, maxParts int) (bool, int) { scratch := make([]btcutil.Amount, len(channels)) var totalBandwidth btcutil.Amount for i, channel := range channels { scratch[i] = channel.LocalBalance totalBandwidth += channel.LocalBalance } if totalBandwidth < amt { return false, 0 } split := amt for shard := 0; shard <= maxParts; { paid := false for i := 0; i < len(scratch); i++ { if scratch[i] >= split { scratch[i] -= split amt -= split paid = true shard++ break } } if amt == 0 { return true, shard } if !paid { split /= 2 } else { split = amt } } return false, 0 }