package liquidity import ( "context" "github.com/btcsuite/btcd/btcutil" "github.com/lightninglabs/loop" "github.com/lightninglabs/loop/labels" "github.com/lightninglabs/loop/loopdb" "github.com/lightninglabs/loop/swap" "github.com/lightningnetwork/lnd/lnwire" "github.com/lightningnetwork/lnd/routing/route" ) // Compile-time assertion that loopOutBuilder satisfies the swapBuilder // interface. var _ swapBuilder = (*loopOutBuilder)(nil) func newLoopOutBuilder(cfg *Config) *loopOutBuilder { return &loopOutBuilder{ cfg: cfg, } } type loopOutBuilder struct { // cfg contains all the external functionality we require to create // swaps. cfg *Config } // swapType returns the swap type that the builder is responsible for creating. func (b *loopOutBuilder) swapType() swap.Type { return swap.TypeOut } // maySwap checks whether we can currently execute a swap, examining the // current on-chain fee conditions relevant to our swap type against our fee // restrictions. // // For loop out, we check whether the fees required for our on-chain sweep // transaction exceed our fee limits. func (b *loopOutBuilder) maySwap(ctx context.Context, params Parameters) error { estimate, err := b.cfg.Lnd.WalletKit.EstimateFeeRate( ctx, params.SweepConfTarget, ) if err != nil { return err } return params.FeeLimit.mayLoopOut(estimate) } // inUse examines our current swap traffic to determine whether we should // we can perform a swap for the peer/ channels provided. func (b *loopOutBuilder) inUse(traffic *swapTraffic, peer route.Vertex, channels []lnwire.ShortChannelID) error { for _, chanID := range channels { lastFail, recentFail := traffic.failedLoopOut[chanID] if recentFail { log.Debugf("Channel: %v not eligible for suggestions, "+ "was part of a failed swap at: %v", chanID, lastFail) return newReasonError(ReasonFailureBackoff) } if traffic.ongoingLoopOut[chanID] { log.Debugf("Channel: %v not eligible for suggestions, "+ "ongoing loop out utilizing channel", chanID) return newReasonError(ReasonLoopOut) } } if traffic.ongoingLoopIn[peer] { log.Debugf("Peer: %x not eligible for suggestions ongoing "+ "loop in utilizing peer", peer) return newReasonError(ReasonLoopIn) } return nil } // buildSwap creates a swap for the target peer/channels provided. The autoloop // boolean indicates whether this swap will actually be executed, because there // are some calls we can leave out if this swap is just for a dry run (ie, when // we are just demonstrating the actions that autoloop _would_ take, but not // actually executing the swap). // // For loop out, we don't bother generating a new wallet address if this is a // dry-run, and we do not add the autoloop label to the recommended swap. func (b *loopOutBuilder) buildSwap(ctx context.Context, pubkey route.Vertex, channels []lnwire.ShortChannelID, amount btcutil.Amount, autoloop bool, params Parameters) (swapSuggestion, error) { quote, err := b.cfg.LoopOutQuote( ctx, &loop.LoopOutQuoteRequest{ Amount: amount, SweepConfTarget: params.SweepConfTarget, SwapPublicationDeadline: b.cfg.Clock.Now(), }, ) if err != nil { return nil, err } log.Debugf("quote for suggestion: %v, swap fee: %v, "+ "miner fee: %v, prepay: %v", amount, quote.SwapFee, quote.MinerFee, quote.PrepayAmount) // Check that the estimated fees for the suggested swap are below the // fee limits configured. if err := params.FeeLimit.loopOutLimits(amount, quote); err != nil { return nil, err } // Break down our fees into appropriate categories for our swap. Our // quote does not provide any off-chain routing estimates for us, so // we just set our fees from the amounts that we expect to route. We // don't have any off-chain fee estimation, so we just use the exact // prepay, swap and miner fee provided by the server and split our // remaining fees up from there. prepayMaxFee, routeMaxFee, minerFee := params.FeeLimit.loopOutFees( amount, quote, ) var chanSet loopdb.ChannelSet for _, channel := range channels { chanSet = append(chanSet, channel.ToUint64()) } // Create a request with our calculated routing fees. We can use the // swap fee, prepay amount and miner fee from the quote because we have // already validated them. request := loop.OutRequest{ Amount: amount, OutgoingChanSet: chanSet, MaxPrepayRoutingFee: prepayMaxFee, MaxSwapRoutingFee: routeMaxFee, MaxMinerFee: minerFee, MaxSwapFee: quote.SwapFee, MaxPrepayAmount: quote.PrepayAmount, SweepConfTarget: params.SweepConfTarget, Initiator: autoloopSwapInitiator, } if autoloop { request.Label = labels.AutoloopLabel(swap.TypeOut) addr, err := b.cfg.Lnd.WalletKit.NextAddr(ctx) if err != nil { return nil, err } request.DestAddr = addr } return &loopOutSwapSuggestion{ OutRequest: request, }, nil }