multi: allow loop in last hop restriction

Author: joostjager

cmd/loop/loopin.go

@@ -7,27 +7,36 @@ import (
 	"github.com/btcsuite/btcutil"
 	"github.com/lightninglabs/loop/looprpc"
 	"github.com/lightninglabs/loop/swap"
+	"github.com/lightningnetwork/lnd/routing/route"
 	"github.com/urfave/cli"
 )
 
-var loopInCommand = cli.Command{
-	Name:      "in",
-	Usage:     "perform an on-chain to off-chain swap (loop in)",
-	ArgsUsage: "amt",
-	Description: `
+var (
+	lastHopFlag = cli.StringFlag{
+		Name:  "last_hop",
+		Usage: "the pubkey of the last hop to use for this swap",
+	}
+
+	loopInCommand = cli.Command{
+		Name:      "in",
+		Usage:     "perform an on-chain to off-chain swap (loop in)",
+		ArgsUsage: "amt",
+		Description: `
 		Send the amount in satoshis specified by the amt argument off-chain.`,
-	Flags: []cli.Flag{
-		cli.Uint64Flag{
-			Name:  "amt",
-			Usage: "the amount in satoshis to loop in",
-		},
-		cli.BoolFlag{
-			Name:  "external",
-			Usage: "expect htlc to be published externally",
+		Flags: []cli.Flag{
+			cli.Uint64Flag{
+				Name:  "amt",
+				Usage: "the amount in satoshis to loop in",
+			},
+			cli.BoolFlag{
+				Name:  "external",
+				Usage: "expect htlc to be published externally",
+			},
+			lastHopFlag,
 		},
-	},
-	Action: loopIn,
-}
+		Action: loopIn,
+	}
+)
 
 func loopIn(ctx *cli.Context) error {
 	args := ctx.Args()
@@ -73,12 +82,25 @@ func loopIn(ctx *cli.Context) error {
 		return err
 	}
 
-	resp, err := client.LoopIn(context.Background(), &looprpc.LoopInRequest{
+	req := &looprpc.LoopInRequest{
 		Amt:          int64(amt),
 		MaxMinerFee:  int64(limits.maxMinerFee),
 		MaxSwapFee:   int64(limits.maxSwapFee),
 		ExternalHtlc: external,
-	})
+	}
+
+	if ctx.IsSet(lastHopFlag.Name) {
+		lastHop, err := route.NewVertexFromStr(
+			ctx.String(lastHopFlag.Name),
+		)
+		if err != nil {
+			return err
+		}
+
+		req.LastHop = lastHop[:]
+	}
+
+	resp, err := client.LoopIn(context.Background(), req)
 	if err != nil {
 		return err
 	}

loopin.go

@@ -114,7 +114,7 @@ func newLoopInSwap(globalCtx context.Context, cfg *swapConfig,
 	// htlc.
 	log.Infof("Initiating swap request at height %v", currentHeight)
 	swapResp, err := cfg.server.NewLoopInSwap(globalCtx, swapHash,
-		request.Amount, senderKey, swapInvoice,
+		request.Amount, senderKey, swapInvoice, request.LastHop,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("cannot initiate swap: %v", err)

looprpc/server.pb.go

@@ -78,6 +78,7 @@ message ServerLoopInRequest {
     bytes swap_hash = 2;
     uint64 amt = 3;
     string swap_invoice = 4;
+    bytes last_hop = 5;
 }
 
 message ServerLoopInResponse {

looprpc/server.proto

@@ -11,6 +11,7 @@ import (
 	"github.com/lightninglabs/loop/test"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/routing/route"
 	"github.com/lightningnetwork/lnd/zpay32"
 )
 
@@ -127,7 +128,7 @@ func getInvoice(hash lntypes.Hash, amt btcutil.Amount, memo string) (string, err
 
 func (s *serverMock) NewLoopInSwap(ctx context.Context,
 	swapHash lntypes.Hash, amount btcutil.Amount,
-	senderKey [33]byte, swapInvoice string) (
+	senderKey [33]byte, swapInvoice string, lastHop *route.Vertex) (
 	*newLoopInResponse, error) {
 
 	_, receiverKey := test.CreateKey(101)

server_mock_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/lightninglabs/loop/looprpc"
 	"github.com/lightninglabs/loop/lsat"
 	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/routing/route"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 )
@@ -40,7 +41,7 @@ type swapServerClient interface {
 
 	NewLoopInSwap(ctx context.Context,
 		swapHash lntypes.Hash, amount btcutil.Amount,
-		senderKey [33]byte, swapInvoice string) (
+		senderKey [33]byte, swapInvoice string, lastHop *route.Vertex) (
 		*newLoopInResponse, error)
 }
 
@@ -203,18 +204,22 @@ func (s *grpcSwapServerClient) NewLoopOutSwap(ctx context.Context,
 
 func (s *grpcSwapServerClient) NewLoopInSwap(ctx context.Context,
 	swapHash lntypes.Hash, amount btcutil.Amount, senderKey [33]byte,
-	swapInvoice string) (*newLoopInResponse, error) {
+	swapInvoice string, lastHop *route.Vertex) (*newLoopInResponse, error) {
 
 	rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout)
 	defer rpcCancel()
-	swapResp, err := s.server.NewLoopInSwap(rpcCtx,
-		&looprpc.ServerLoopInRequest{
-			SwapHash:    swapHash[:],
-			Amt:         uint64(amount),
-			SenderKey:   senderKey[:],
-			SwapInvoice: swapInvoice,
-		},
-	)
+
+	req := &looprpc.ServerLoopInRequest{
+		SwapHash:    swapHash[:],
+		Amt:         uint64(amount),
+		SenderKey:   senderKey[:],
+		SwapInvoice: swapInvoice,
+	}
+	if lastHop != nil {
+		req.LastHop = lastHop[:]
+	}
+
+	swapResp, err := s.server.NewLoopInSwap(rpcCtx, req)
 	if err != nil {
 		return nil, err
 	}