loopd: receive external HTLC flag in loop in quote request

client.go

@@ -470,6 +470,15 @@ func (s *Client) LoopInQuote(ctx context.Context,
 		request.Amount*btcutil.Amount(terms.SwapFeeRate)/
 			btcutil.Amount(swap.FeeRateTotalParts)
 
+	// We don't calculate the on-chain fee if the HTLC is going to be
+	// published externally.
+	if request.ExternalHtlc {
+		return &LoopInQuote{
+			SwapFee:  swapFee,
+			MinerFee: 0,
+		}, nil
+	}
+	
 	// Get estimate for miner fee.
 	minerFee, err := s.lndServices.Client.EstimateFeeToP2WSH(
 		ctx, request.Amount, request.HtlcConfTarget,

cmd/loopd/swapclient_server.go

@@ -306,6 +306,7 @@ func (s *swapClientServer) GetLoopInQuote(ctx context.Context,
 	quote, err := s.impl.LoopInQuote(ctx, &loop.LoopInQuoteRequest{
 		Amount:         btcutil.Amount(req.Amt),
 		HtlcConfTarget: defaultConfTarget,
+		ExternalHtlc:   req.ExternalHtlc,
 	})
 	if err != nil {
 		return nil, err

interface.go

@@ -224,6 +224,10 @@ type LoopInQuoteRequest struct {
 	// HtlcConfTarget specifies the targeted confirmation target for the
 	// client sweep tx.
 	HtlcConfTarget int32
+
+	// ExternalHtlc specifies whether the htlc is published by an external
+	// source.
+	ExternalHtlc bool
 }
 
 // LoopInQuote contains estimates for the fees making up the total swap cost