loop out: allow outbound channel set for multi-loops

client.go

@@ -359,9 +359,8 @@ func (s *Client) resumeSwaps(ctx context.Context,
 func (s *Client) LoopOut(globalCtx context.Context,
 	request *OutRequest) (*lntypes.Hash, btcutil.Address, error) {
 
-	log.Infof("LoopOut %v to %v (channel: %v)",
-		request.Amount, request.DestAddr,
-		request.LoopOutChannel,
+	log.Infof("LoopOut %v to %v (channels: %v)",
+		request.Amount, request.DestAddr, request.OutgoingChanSet,
 	)
 
 	if err := s.waitForInitialized(globalCtx); err != nil {

cmd/loop/loopout.go

@@ -3,6 +3,8 @@ package main
 import (
 	"context"
 	"fmt"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/btcsuite/btcutil"
@@ -25,10 +27,10 @@ var loopOutCommand = cli.Command{
 	Optionally a BASE58/bech32 encoded bitcoin destination address may be
 	specified. If not specified, a new wallet address will be generated.`,
 	Flags: []cli.Flag{
-		cli.Uint64Flag{
+		cli.StringFlag{
 			Name: "channel",
-			Usage: "the 8-byte compact channel ID of the channel " +
-				"to loop out",
+			Usage: "the comma-separated list of short " +
+				"channel IDs of the channels to loop out",
 		},
 		cli.StringFlag{
 			Name: "addr",
@@ -87,6 +89,17 @@ func loopOut(ctx *cli.Context) error {
 		return err
 	}
 
+	// Parse outgoing channel set.
+	chanStrings := strings.Split(ctx.String("channel"), ",")
+	var outgoingChanSet []uint64
+	for _, chanString := range chanStrings {
+		chanID, err := strconv.ParseUint(chanString, 10, 64)
+		if err != nil {
+			return err
+		}
+		outgoingChanSet = append(outgoingChanSet, chanID)
+	}
+
 	var destAddr string
 	switch {
 	case ctx.IsSet("addr"):
@@ -145,11 +158,6 @@ func loopOut(ctx *cli.Context) error {
 		return err
 	}
 
-	var unchargeChannel uint64
-	if ctx.IsSet("channel") {
-		unchargeChannel = ctx.Uint64("channel")
-	}
-
 	resp, err := client.LoopOut(context.Background(), &looprpc.LoopOutRequest{
 		Amt:                     int64(amt),
 		Dest:                    destAddr,
@@ -158,7 +166,7 @@ func loopOut(ctx *cli.Context) error {
 		MaxSwapFee:              int64(limits.maxSwapFee),
 		MaxPrepayRoutingFee:     int64(*limits.maxPrepayRoutingFee),
 		MaxSwapRoutingFee:       int64(*limits.maxSwapRoutingFee),
-		LoopOutChannel:          unchargeChannel,
+		OutgoingChanSet:         outgoingChanSet,
 		SweepConfTarget:         sweepConfTarget,
 		SwapPublicationDeadline: uint64(swapDeadline.Unix()),
 	})

go.mod

@@ -1,7 +1,7 @@
 module github.com/lightninglabs/loop
 
 require (
-	github.com/btcsuite/btcd v0.20.1-beta
+	github.com/btcsuite/btcd v0.20.1-beta.0.20200515232429-9f0179fd2c46
 	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f
 	github.com/btcsuite/btcutil v1.0.2
 	github.com/coreos/bbolt v1.3.3
@@ -11,7 +11,7 @@ require (
 	github.com/grpc-ecosystem/grpc-gateway v1.12.2
 	github.com/jessevdk/go-flags v1.4.0
 	github.com/lightninglabs/protobuf-hex-display v1.3.3-0.20191212020323-b444784ce75d
-	github.com/lightningnetwork/lnd v0.10.0-beta.rc5
+	github.com/lightningnetwork/lnd v0.10.1-beta.rc1
 	github.com/lightningnetwork/lnd/queue v1.0.3
 	github.com/urfave/cli v1.20.0
 	golang.org/x/net v0.0.0-20191002035440-2ec189313ef0

go.sum

@@ -24,6 +24,9 @@ github.com/btcsuite/btcd v0.0.0-20190629003639-c26ffa870fd8/go.mod h1:3J08xEfcug
 github.com/btcsuite/btcd v0.0.0-20190824003749-130ea5bddde3/go.mod h1:3J08xEfcugPacsc34/LKRU2yO7YmuT8yt28J8k2+rrI=
 github.com/btcsuite/btcd v0.20.1-beta h1:Ik4hyJqN8Jfyv3S4AGBOmyouMsYE3EdYODkMbQjwPGw=
 github.com/btcsuite/btcd v0.20.1-beta/go.mod h1:wVuoA8VJLEcwgqHBwHmzLRazpKxTv13Px/pDuV7OomQ=
+github.com/btcsuite/btcd v0.20.1-beta.0.20200513120220-b470eee47728/go.mod h1:wVuoA8VJLEcwgqHBwHmzLRazpKxTv13Px/pDuV7OomQ=
+github.com/btcsuite/btcd v0.20.1-beta.0.20200515232429-9f0179fd2c46 h1:QyTpiR5nQe94vza2qkvf7Ns8XX2Rjh/vdIhO3RzGj4o=
+github.com/btcsuite/btcd v0.20.1-beta.0.20200515232429-9f0179fd2c46/go.mod h1:Yktc19YNjh/Iz2//CX0vfRTS4IJKM/RKO5YZ9Fn+Pgo=
 github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f h1:bAs4lUbRJpnnkd9VhRV3jjAVU7DJVjMaK+IsvSeZvFo=
 github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f/go.mod h1:TdznJufoqS23FtqVCzL0ZqgP5MqXbb4fg/WgDys70nA=
 github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d h1:yJzD/yFppdVCf6ApMkVy8cUxV0XrxdP9rVf6D87/Mng=
@@ -34,6 +37,8 @@ github.com/btcsuite/btcutil/psbt v1.0.2 h1:gCVY3KxdoEVU7Q6TjusPO+GANIwVgr9yTLqM+
 github.com/btcsuite/btcutil/psbt v1.0.2/go.mod h1:LVveMu4VaNSkIRTZu2+ut0HDBRuYjqGocxDMNS1KuGQ=
 github.com/btcsuite/btcwallet v0.11.1-0.20200403222202-ada7ca077ebb h1:kkq2SSCy+OrC7GVZLIqutoHVR2yW4SJQdX70jtmuLDI=
 github.com/btcsuite/btcwallet v0.11.1-0.20200403222202-ada7ca077ebb/go.mod h1:9fJNm1aXi4q9P5Nk23mmqppCy1Le3f2/JMWj9UXKkCc=
+github.com/btcsuite/btcwallet v0.11.1-0.20200515224913-e0e62245ecbe h1:0m9uXDcnUc3Fv72635O/MfLbhbW+0hfSVgRiWezpkHU=
+github.com/btcsuite/btcwallet v0.11.1-0.20200515224913-e0e62245ecbe/go.mod h1:9+AH3V5mcTtNXTKe+fe63fDLKGOwQbZqmvOVUef+JFE=
 github.com/btcsuite/btcwallet/wallet/txauthor v1.0.0 h1:KGHMW5sd7yDdDMkCZ/JpP0KltolFsQcB973brBnfj4c=
 github.com/btcsuite/btcwallet/wallet/txauthor v1.0.0/go.mod h1:VufDts7bd/zs3GV13f/lXc/0lXrPnvxD/NvmpG/FEKU=
 github.com/btcsuite/btcwallet/wallet/txrules v1.0.0 h1:2VsfS0sBedcM5KmDzRMT3+b6xobqWveZGvjb+jFez5w=
@@ -46,6 +51,8 @@ github.com/btcsuite/btcwallet/walletdb v1.3.1 h1:lW1Ac3F1jJY4K11P+YQtRNcP5jFk27A
 github.com/btcsuite/btcwallet/walletdb v1.3.1/go.mod h1:9cwc1Yyg4uvd4ZdfdoMnALji+V9gfWSMfxEdLdR5Vwc=
 github.com/btcsuite/btcwallet/wtxmgr v1.0.0 h1:aIHgViEmZmZfe0tQQqF1xyd2qBqFWxX5vZXkkbjtbeA=
 github.com/btcsuite/btcwallet/wtxmgr v1.0.0/go.mod h1:vc4gBprll6BP0UJ+AIGDaySoc7MdAmZf8kelfNb8CFY=
+github.com/btcsuite/btcwallet/wtxmgr v1.1.1-0.20200515224913-e0e62245ecbe h1:yQbJVYfsKbdqDQNLxd4hhiLSiMkIygefW5mSHMsdKpc=
+github.com/btcsuite/btcwallet/wtxmgr v1.1.1-0.20200515224913-e0e62245ecbe/go.mod h1:OwC0W0HhUszbWdvJvH6xvgabKSJ0lXl11YbmmqF9YXQ=
 github.com/btcsuite/fastsha256 v0.0.0-20160815193821-637e65642941 h1:kij1x2aL7VE6gtx8KMIt8PGPgI5GV9LgtHFG5KaEMPY=
 github.com/btcsuite/fastsha256 v0.0.0-20160815193821-637e65642941/go.mod h1:QcFA8DZHtuIAdYKCq/BzELOaznRsCvwf4zTPmaYwaig=
 github.com/btcsuite/go-socks v0.0.0-20170105172521-4720035b7bfd h1:R/opQEbFEy9JGkIguV40SvRY1uliPX8ifOvi6ICsFCw=
@@ -157,6 +164,8 @@ github.com/lightningnetwork/lightning-onion v1.0.1 h1:qChGgS5+aPxFeR6JiUsGvanei1
 github.com/lightningnetwork/lightning-onion v1.0.1/go.mod h1:rigfi6Af/KqsF7Za0hOgcyq2PNH4AN70AaMRxcJkff4=
 github.com/lightningnetwork/lnd v0.10.0-beta.rc5 h1:HcX35Djwk+xoNQe/LA7HnQ11jzbq68TAcpBluhNIKqc=
 github.com/lightningnetwork/lnd v0.10.0-beta.rc5/go.mod h1:mEnmP+sSgiKUFBozT3I5xEOgRAREMEWd/3lcWDrB+5E=
+github.com/lightningnetwork/lnd v0.10.1-beta.rc1 h1:4uBkLHrxeIf6ad5AHlFhGcOhtbvmYwK4iTcDMixmLpw=
+github.com/lightningnetwork/lnd v0.10.1-beta.rc1/go.mod h1:mRd+8n/QOlAiolWVnt1RaTzxVvOyplT3J5uYwUb/EDw=
 github.com/lightningnetwork/lnd/cert v1.0.2/go.mod h1:fmtemlSMf5t4hsQmcprSoOykypAPp+9c+0d0iqTScMo=
 github.com/lightningnetwork/lnd/queue v1.0.1 h1:jzJKcTy3Nj5lQrooJ3aaw9Lau3I0IwvQR5sqtjdv2R0=
 github.com/lightningnetwork/lnd/queue v1.0.1/go.mod h1:vaQwexir73flPW43Mrm7JOgJHmcEFBWWSl9HlyASoms=
@@ -222,6 +231,8 @@ golang.org/x/crypto v0.0.0-20190211182817-74369b46fc67/go.mod h1:6SG95UA2DQfeDnf
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d h1:2+ZP7EfsZV7Vvmx3TIqSlSzATMkTAKqM14YGFPoSKjI=
 golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37 h1:cg5LA/zNPRzIXIWSCxQW10Rvpy94aQh3LT/ShoCpkHw=
+golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/lint v0.0.0-20180702182130-06c8688daad7/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=

interface.go

@@ -64,9 +64,9 @@ type OutRequest struct {
 	// client sweep tx.
 	SweepConfTarget int32
 
-	// LoopOutChannel optionally specifies the short channel id of the
-	// channel to loop out.
-	LoopOutChannel *uint64
+	// OutgoingChanSet optionally specifies the short channel ids of the
+	// channels that may be used to loop out.
+	OutgoingChanSet loopdb.ChannelSet
 
 	// SwapPublicationDeadline can be set by the client to allow the server
 	// delaying publication of the swap HTLC to save on chain fees.

lndclient/lnd_services.go

@@ -31,7 +31,7 @@ var (
 	minimalCompatibleVersion = &verrpc.Version{
 		AppMajor: 0,
 		AppMinor: 10,
-		AppPatch: 0,
+		AppPatch: 1,
 		BuildTags: []string{
 			"signrpc", "walletrpc", "chainrpc", "invoicesrpc",
 		},

lndclient/router_client.go

@@ -64,10 +64,20 @@ type SendPaymentRequest struct {
 	// are only processed when the Invoice field is empty.
 	Invoice string
 
-	MaxFee          btcutil.Amount
-	MaxCltv         *int32
-	OutgoingChannel *uint64
-	Timeout         time.Duration
+	// MaxFee is the fee limit for this payment.
+	MaxFee btcutil.Amount
+
+	// MaxCltv is the maximum timelock for this payment. If nil, there is no
+	// maximum.
+	MaxCltv *int32
+
+	// OutgoingChanIds is a restriction on the set of possible outgoing
+	// channels. If nil or empty, there is no restriction.
+	OutgoingChanIds []uint64
+
+	// Timeout is the payment loop timeout. After this time, no new payment
+	// attempts will be started.
+	Timeout time.Duration
 
 	// Target is the node in which the payment should be routed towards.
 	Target route.Vertex
@@ -126,17 +136,16 @@ func (r *routerClient) SendPayment(ctx context.Context,
 
 	rpcCtx := r.routerKitMac.WithMacaroonAuth(ctx)
 	rpcReq := &routerrpc.SendPaymentRequest{
-		FeeLimitSat:    int64(request.MaxFee),
-		PaymentRequest: request.Invoice,
-		TimeoutSeconds: int32(request.Timeout.Seconds()),
-		MaxParts:       request.MaxParts,
+		FeeLimitSat:     int64(request.MaxFee),
+		PaymentRequest:  request.Invoice,
+		TimeoutSeconds:  int32(request.Timeout.Seconds()),
+		MaxParts:        request.MaxParts,
+		OutgoingChanIds: request.OutgoingChanIds,
 	}
 	if request.MaxCltv != nil {
 		rpcReq.CltvLimit = *request.MaxCltv
 	}
-	if request.OutgoingChannel != nil {
-		rpcReq.OutgoingChanId = *request.OutgoingChannel
-	}
+
 	if request.LastHopPubkey != nil {
 		rpcReq.LastHopPubkey = request.LastHopPubkey[:]
 	}

loopd/start.go

@@ -24,7 +24,7 @@ var (
 	LoopMinRequiredLndVersion = &verrpc.Version{
 		AppMajor: 0,
 		AppMinor: 10,
-		AppPatch: 0,
+		AppPatch: 1,
 		BuildTags: []string{
 			"signrpc", "walletrpc", "chainrpc", "invoicesrpc",
 		},

loopd/swapclient_server.go

@@ -89,9 +89,19 @@ func (s *swapClientServer) LoopOut(ctx context.Context,
 			int64(in.SwapPublicationDeadline), 0,
 		),
 	}
-	if in.LoopOutChannel != 0 {
-		req.LoopOutChannel = &in.LoopOutChannel
+
+	switch {
+	case in.LoopOutChannel != 0 && len(in.OutgoingChanSet) > 0:
+		return nil, errors.New("loop_out_channel and outgoing_" +
+			"chan_ids are mutually exclusive")
+
+	case in.LoopOutChannel != 0:
+		req.OutgoingChanSet = loopdb.ChannelSet{in.LoopOutChannel}
+
+	default:
+		req.OutgoingChanSet = in.OutgoingChanSet
 	}
+
 	hash, htlc, err := s.impl.LoopOut(ctx, req)
 	if err != nil {
 		log.Errorf("LoopOut: %v", err)

loopd/view.go

@@ -2,7 +2,6 @@ package loopd
 
 import (
 	"fmt"
-	"strconv"
 
 	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/lightninglabs/loop"
@@ -64,13 +63,8 @@ func viewOut(swapClient *loop.Client, chainParams *chaincfg.Params) error {
 		fmt.Printf("   Preimage: %v\n", s.Contract.Preimage)
 		fmt.Printf("   Htlc address: %v\n", htlc.Address)
 
-		unchargeChannel := "any"
-		if s.Contract.UnchargeChannel != nil {
-			unchargeChannel = strconv.FormatUint(
-				*s.Contract.UnchargeChannel, 10,
-			)
-		}
-		fmt.Printf("   Uncharge channel: %v\n", unchargeChannel)
+		fmt.Printf("   Uncharge channels: %v\n",
+			s.Contract.OutgoingChanSet)
 		fmt.Printf("   Dest: %v\n", s.Contract.DestAddr)
 		fmt.Printf("   Amt: %v, Expiry: %v\n",
 			s.Contract.AmountRequested, s.Contract.CltvExpiry,

loopdb/loopout.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"encoding/binary"
 	"fmt"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/btcsuite/btcd/chaincfg"
@@ -34,9 +36,9 @@ type LoopOutContract struct {
 	// client sweep tx.
 	SweepConfTarget int32
 
-	// TargetChannel is the channel to loop out. If zero, any channel may
-	// be used.
-	UnchargeChannel *uint64
+	// OutgoingChanSet is the set of short ids of channels that may be used.
+	// If empty, any channel may be used.
+	OutgoingChanSet ChannelSet
 
 	// PrepayInvoice is the invoice that the client should pay to the
 	// server that will be returned if the swap is complete.
@@ -53,6 +55,34 @@ type LoopOutContract struct {
 	SwapPublicationDeadline time.Time
 }
 
+// ChannelSet stores a set of channels.
+type ChannelSet []uint64
+
+// String returns the human-readable representation of a channel set.
+func (c ChannelSet) String() string {
+	channelStrings := make([]string, len(c))
+	for i, chanID := range c {
+		channelStrings[i] = strconv.FormatUint(chanID, 10)
+	}
+	return strings.Join(channelStrings, ",")
+}
+
+// NewChannelSet instantiates a new channel set and verifies that there are no
+// duplicates present.
+func NewChannelSet(set []uint64) (ChannelSet, error) {
+	// Check channel set for duplicates.
+	chanSet := make(map[uint64]struct{})
+	for _, chanID := range set {
+		if _, exists := chanSet[chanID]; exists {
+			return nil, fmt.Errorf("duplicate chan in set: id=%v",
+				chanID)
+		}
+		chanSet[chanID] = struct{}{}
+	}
+
+	return ChannelSet(set), nil
+}
+
 // LoopOut is a combination of the contract and the updates.
 type LoopOut struct {
 	Loop
@@ -161,7 +191,7 @@ func deserializeLoopOutContract(value []byte, chainParams *chaincfg.Params) (
 		return nil, err
 	}
 	if unchargeChannel != 0 {
-		contract.UnchargeChannel = &unchargeChannel
+		contract.OutgoingChanSet = ChannelSet{unchargeChannel}
 	}
 
 	var deadlineNano int64
@@ -248,10 +278,9 @@ func serializeLoopOutContract(swap *LoopOutContract) (
 		return nil, err
 	}
 
-	var unchargeChannel uint64
-	if swap.UnchargeChannel != nil {
-		unchargeChannel = *swap.UnchargeChannel
-	}
+	// Always write no outgoing channel. This field is replaced by an
+	// outgoing channel set.
+	unchargeChannel := uint64(0)
 	if err := binary.Write(&b, byteOrder, unchargeChannel); err != nil {
 		return nil, err
 	}