loopd: quoting for static address loop-ins

Author: hieblmi

client.go

@@ -645,9 +645,9 @@ func (s *Client) LoopIn(globalCtx context.Context,
 	return swapInfo, nil
 }
 
-// LoopInQuote takes an amount and returns a break down of estimated
-// costs for the client. Both the swap server and the on-chain fee estimator are
-// queried to get to build the quote response.
+// LoopInQuote takes an amount and returns a breakdown of estimated costs for
+// the client. Both the swap server and the on-chain fee estimator are queried
+// to get to build the quote response.
 func (s *Client) LoopInQuote(ctx context.Context,
 	request *LoopInQuoteRequest) (*LoopInQuote, error) {
 
@@ -693,7 +693,7 @@ func (s *Client) LoopInQuote(ctx context.Context,
 
 	quote, err := s.Server.GetLoopInQuote(
 		ctx, request.Amount, s.lndServices.NodePubkey, request.LastHop,
-		request.RouteHints, request.Initiator,
+		request.RouteHints, request.Initiator, request.NumDeposits,
 	)
 	if err != nil {
 		return nil, err
@@ -703,7 +703,9 @@ func (s *Client) LoopInQuote(ctx context.Context,
 
 	// We don't calculate the on-chain fee if the HTLC is going to be
 	// published externally.
-	if request.ExternalHtlc {
+	// We also don't calculate the on-chain fee if the loop in is funded by
+	// static address deposits because we don't publish the HTLC on-chain.
+	if request.ExternalHtlc || request.NumDeposits > 0 {
 		return &LoopInQuote{
 			SwapFee:  swapFee,
 			MinerFee: 0,

interface.go

@@ -288,6 +288,12 @@ type LoopInQuoteRequest struct {
 	// initiated the swap (loop CLI, autolooper, LiT UI and so on) and is
 	// appended to the user agent string.
 	Initiator string
+
+	// The number of static address deposits the client wants to quote for.
+	// If the number of deposits exceeds one the server will apply a
+	// per-input service fee. This is to cover for the increased on-chain
+	// fee the server has to pay when the sweeping transaction is broadcast.
+	NumDeposits uint32
 }
 
 // LoopInQuote contains estimates for the fees making up the total swap cost

loopd/swapclient_server.go

@@ -748,13 +748,31 @@ func (s *swapClientServer) GetLoopInQuote(ctx context.Context,
 
 	log.Infof("Loop in quote request received")
 
+	var (
+		numDeposits = uint32(len(req.DepositOutpoints))
+		err         error
+	)
+
 	htlcConfTarget, err := validateLoopInRequest(
-		req.ConfTarget, req.ExternalHtlc,
+		req.ConfTarget, req.ExternalHtlc, numDeposits, req.Amt,
 	)
 	if err != nil {
 		return nil, err
 	}
 
+	// Retrieve deposits to calculate their total value.
+	var summary *clientrpc.StaticAddressSummaryResponse
+	if len(req.DepositOutpoints) > 0 {
+		summary, err = s.GetStaticAddressSummary(
+			ctx, &clientrpc.StaticAddressSummaryRequest{
+				Outpoints: req.DepositOutpoints,
+			},
+		)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	var (
 		routeHints [][]zpay32.HopHint
 		lastHop    *route.Vertex
@@ -777,14 +795,26 @@ func (s *swapClientServer) GetLoopInQuote(ctx context.Context,
 		}
 	}
 
+	// The requested amount is 0 here if the request contained deposit
+	// outpoints. In case we quote for deposits we send the server both the
+	// total value and the number of deposits. This is so the server can
+	// probe the total amount and calculate the per input fee.
+	amount := btcutil.Amount(req.Amt)
+	if amount == 0 && len(summary.FilteredDeposits) > 0 {
+		for _, deposit := range summary.FilteredDeposits {
+			amount += btcutil.Amount(deposit.Value)
+		}
+	}
+
 	quote, err := s.impl.LoopInQuote(ctx, &loop.LoopInQuoteRequest{
-		Amount:         btcutil.Amount(req.Amt),
+		Amount:         amount,
 		HtlcConfTarget: htlcConfTarget,
 		ExternalHtlc:   req.ExternalHtlc,
 		LastHop:        lastHop,
 		RouteHints:     routeHints,
 		Private:        req.Private,
 		Initiator:      defaultLoopdInitiator,
+		NumDeposits:    numDeposits,
 	})
 	if err != nil {
 		return nil, err
@@ -881,7 +911,7 @@ func (s *swapClientServer) LoopIn(ctx context.Context,
 	log.Infof("Loop in request received")
 
 	htlcConfTarget, err := validateLoopInRequest(
-		in.HtlcConfTarget, in.ExternalHtlc,
+		in.HtlcConfTarget, in.ExternalHtlc, 0, in.Amt,
 	)
 	if err != nil {
 		return nil, err
@@ -1710,7 +1740,13 @@ func validateConfTarget(target, defaultTarget int32) (int32, error) {
 
 // validateLoopInRequest fails if the mutually exclusive conf target and
 // external parameters are both set.
-func validateLoopInRequest(htlcConfTarget int32, external bool) (int32, error) {
+func validateLoopInRequest(htlcConfTarget int32, external bool,
+	numDeposits uint32, amount int64) (int32, error) {
+
+	if amount == 0 && numDeposits == 0 {
+		return 0, errors.New("either amount or deposits must be set")
+	}
+
 	// 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 {
@@ -1724,6 +1760,12 @@ func validateLoopInRequest(htlcConfTarget int32, external bool) (int32, error) {
 		return 0, nil
 	}
 
+	// If the loop in uses static address deposits, we do not need to set a
+	// confirmation target since the HTLC won't be published by the client.
+	if numDeposits > 0 {
+		return 0, nil
+	}
+
 	return validateConfTarget(htlcConfTarget, loop.DefaultHtlcConfTarget)
 }
 

loopd/swapclient_server_test.go

@@ -145,55 +145,76 @@ func TestValidateConfTarget(t *testing.T) {
 func TestValidateLoopInRequest(t *testing.T) {
 	tests := []struct {
 		name           string
+		amount         int64
+		numDeposits    uint32
 		external       bool
 		confTarget     int32
 		expectErr      bool
 		expectedTarget int32
 	}{
 		{
 			name:           "external and htlc conf set",
+			amount:         100_000,
 			external:       true,
 			confTarget:     1,
 			expectErr:      true,
 			expectedTarget: 0,
 		},
 		{
 			name:           "external and no conf",
+			amount:         100_000,
 			external:       true,
 			confTarget:     0,
 			expectErr:      false,
 			expectedTarget: 0,
 		},
 		{
 			name:           "not external, zero conf",
+			amount:         100_000,
 			external:       false,
 			confTarget:     0,
 			expectErr:      false,
 			expectedTarget: loop.DefaultHtlcConfTarget,
 		},
 		{
 			name:           "not external, bad conf",
+			amount:         100_000,
 			external:       false,
 			confTarget:     1,
 			expectErr:      true,
 			expectedTarget: 0,
 		},
 		{
 			name:           "not external, ok conf",
+			amount:         100_000,
 			external:       false,
 			confTarget:     5,
 			expectErr:      false,
 			expectedTarget: 5,
 		},
+		{
+			name:           "not external, amount no deposit",
+			amount:         100_000,
+			numDeposits:    0,
+			external:       false,
+			expectErr:      false,
+			expectedTarget: loop.DefaultHtlcConfTarget,
+		},
+		{
+			name:        "not external, deposit no amount",
+			amount:      100_000,
+			numDeposits: 1,
+			external:    false,
+			expectErr:   false,
+		},
 	}
 
 	for _, test := range tests {
-		test := test
-
 		t.Run(test.name, func(t *testing.T) {
 			external := test.external
 			conf, err := validateLoopInRequest(
-				test.confTarget, external,
+				test.confTarget, external, test.numDeposits,
+				test.amount,
 			)
 
 			if test.expectErr {

loopin.go

@@ -128,7 +128,7 @@ func newLoopInSwap(globalCtx context.Context, cfg *swapConfig,
 	// hints.
 	quote, err := cfg.server.GetLoopInQuote(
 		globalCtx, request.Amount, cfg.lnd.NodePubkey, request.LastHop,
-		request.RouteHints, request.Initiator,
+		request.RouteHints, request.Initiator, 0,
 	)
 	if err != nil {
 		return nil, wrapGrpcError("loop in terms", err)

server_mock_test.go

@@ -225,7 +225,8 @@ func (s *serverMock) GetLoopInTerms(ctx context.Context, initiator string) (
 }
 
 func (s *serverMock) GetLoopInQuote(context.Context, btcutil.Amount,
-	route.Vertex, *route.Vertex, [][]zpay32.HopHint, string) (*LoopInQuote, error) {
+	route.Vertex, *route.Vertex, [][]zpay32.HopHint, string,
+	uint32) (*LoopInQuote, error) {
 
 	return &LoopInQuote{
 		SwapFee:   testSwapFee,

swap_server_client.go

@@ -82,7 +82,7 @@ type swapServerClient interface {
 	GetLoopInQuote(ctx context.Context, amt btcutil.Amount,
 		pubKey route.Vertex, lastHop *route.Vertex,
 		routeHints [][]zpay32.HopHint,
-		initiator string) (*LoopInQuote, error)
+		initiator string, numDeposits uint32) (*LoopInQuote, error)
 
 	Probe(ctx context.Context, amt btcutil.Amount, target route.Vertex,
 		lastHop *route.Vertex, routeHints [][]zpay32.HopHint) error
@@ -268,7 +268,8 @@ func (s *grpcSwapServerClient) GetLoopInTerms(ctx context.Context,
 
 func (s *grpcSwapServerClient) GetLoopInQuote(ctx context.Context,
 	amt btcutil.Amount, pubKey route.Vertex, lastHop *route.Vertex,
-	routeHints [][]zpay32.HopHint, initiator string) (*LoopInQuote, error) {
+	routeHints [][]zpay32.HopHint, initiator string,
+	numDeposits uint32) (*LoopInQuote, error) {
 
 	err := s.Probe(ctx, amt, pubKey, lastHop, routeHints)
 	if err != nil && status.Code(err) != codes.Unavailable {
@@ -279,10 +280,11 @@ func (s *grpcSwapServerClient) GetLoopInQuote(ctx context.Context,
 	defer rpcCancel()
 
 	req := &looprpc.ServerLoopInQuoteRequest{
-		Amt:             uint64(amt),
-		ProtocolVersion: loopdb.CurrentRPCProtocolVersion(),
-		Pubkey:          pubKey[:],
-		UserAgent:       UserAgent(initiator),
+		Amt:                      uint64(amt),
+		ProtocolVersion:          loopdb.CurrentRPCProtocolVersion(),
+		Pubkey:                   pubKey[:],
+		UserAgent:                UserAgent(initiator),
+		NumStaticAddressDeposits: numDeposits,
 	}
 
 	if lastHop != nil {