litd: register tapd as aux component of lnd

This commit represents the main integration between lnd running in
integrated mode and tapd providing auxiliary components for custom
channels.

Author: guggero

config.go

@@ -31,6 +31,7 @@ import (
 	"github.com/lightningnetwork/lnd/cert"
 	"github.com/lightningnetwork/lnd/lncfg"
 	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/signal"
 	"github.com/mwitkow/go-conntrack/connhelpers"
 	"golang.org/x/crypto/acme/autocert"
@@ -614,6 +615,19 @@ func loadConfigFile(preCfg *Config, interceptor signal.Interceptor) (*Config,
 	// configuration is fully valid. This also sets up the main logger that
 	// logs to a sub-directory in the .lnd folder.
 	case ModeIntegrated:
+		// For the integration of tapd with lnd, we need to allow tapd
+		// to send custom error messages to peers through the
+		// SendCustomMessage RPC in lnd. Since the error messages aren't
+		// in the custom range, we explicitly need to allow them. This
+		// isn't currently needed in remote mode, because custom
+		// channels are only available if both lnd and tapd are running
+		// in integrated mode. We need to set this value before we call
+		// lnd.ValidateConfig() below, because that's what's going to
+		// inject these values into the lnwire package.
+		cfg.Lnd.ProtocolOptions.CustomMessage = append(
+			cfg.Lnd.ProtocolOptions.CustomMessage, lnwire.MsgError,
+		)
+
 		var err error
 		cfg.Lnd, err = lnd.ValidateConfig(
 			*cfg.Lnd, interceptor, fileParser, flagParser,

go.mod

@@ -25,6 +25,7 @@ require (
 	github.com/lightninglabs/taproot-assets v0.4.2-0.20241031160301-588e58bfae6c
 	github.com/lightningnetwork/lnd v0.18.3-beta.rc3.0.20241025090009-615f3d633e61
 	github.com/lightningnetwork/lnd/cert v1.2.2
+	github.com/lightningnetwork/lnd/fn v1.2.3
 	github.com/lightningnetwork/lnd/kvdb v1.4.10
 	github.com/lightningnetwork/lnd/tlv v1.2.6
 	github.com/lightningnetwork/lnd/tor v1.1.2
@@ -136,7 +137,6 @@ require (
 	github.com/lightninglabs/neutrino/cache v1.1.2 // indirect
 	github.com/lightningnetwork/lightning-onion v1.2.1-0.20240712235311-98bd56499dfb // indirect
 	github.com/lightningnetwork/lnd/clock v1.1.1 // indirect
-	github.com/lightningnetwork/lnd/fn v1.2.3 // indirect
 	github.com/lightningnetwork/lnd/healthcheck v1.2.5 // indirect
 	github.com/lightningnetwork/lnd/queue v1.1.1 // indirect
 	github.com/lightningnetwork/lnd/sqldb v1.0.4 // indirect

terminal.go

@@ -34,9 +34,12 @@ import (
 	"github.com/lightninglabs/lightning-terminal/status"
 	"github.com/lightninglabs/lightning-terminal/subservers"
 	"github.com/lightninglabs/lndclient"
+	taprootassets "github.com/lightninglabs/taproot-assets"
 	"github.com/lightningnetwork/lnd"
 	"github.com/lightningnetwork/lnd/build"
 	"github.com/lightningnetwork/lnd/chainreg"
+	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/funding"
 	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lncfg"
 	"github.com/lightningnetwork/lnd/lnrpc"
@@ -49,10 +52,15 @@ import (
 	"github.com/lightningnetwork/lnd/lnrpc/walletrpc"
 	"github.com/lightningnetwork/lnd/lnrpc/watchtowerrpc"
 	"github.com/lightningnetwork/lnd/lnrpc/wtclientrpc"
+	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwallet/btcwallet"
+	"github.com/lightningnetwork/lnd/lnwallet/chancloser"
 	"github.com/lightningnetwork/lnd/macaroons"
+	"github.com/lightningnetwork/lnd/msgmux"
+	"github.com/lightningnetwork/lnd/routing"
 	"github.com/lightningnetwork/lnd/rpcperms"
 	"github.com/lightningnetwork/lnd/signal"
+	"github.com/lightningnetwork/lnd/sweep"
 	grpcProxy "github.com/mwitkow/grpc-proxy/proxy"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
@@ -507,13 +515,33 @@ func (g *LightningTerminal) start() error {
 			}},
 		}
 
+		var auxComponents lnd.AuxComponents
+		switch g.cfg.TaprootAssetsMode {
+		case ModeRemote, ModeDisable:
+			log.Warnf("Taproot Assets daemon is either disabled " +
+				"or running in remote mode. Taproot Asset " +
+				"channel functionality will NOT be " +
+				"available. To enable, set Taproot Assets " +
+				"mode to 'integrated' in the config file.")
+
+		case ModeIntegrated:
+			components, err := g.buildAuxComponents()
+			if err != nil {
+				return fmt.Errorf("could not build aux "+
+					"components: %w", err)
+			}
+
+			auxComponents = *components
+		}
+
 		implCfg := &lnd.ImplementationCfg{
 			GrpcRegistrar:       g,
 			RestRegistrar:       g,
 			ExternalValidator:   g,
 			DatabaseBuilder:     g.defaultImplCfg.DatabaseBuilder,
 			WalletConfigBuilder: g,
 			ChainControlBuilder: g.defaultImplCfg.ChainControlBuilder,
+			AuxComponents:       auxComponents,
 		}
 
 		g.wg.Add(1)
@@ -1293,6 +1321,59 @@ func (g *LightningTerminal) BuildWalletConfig(ctx context.Context,
 	)
 }
 
+// buildAuxComponent builds the auxiliary components required by lnd when
+// running in integrated mode with tapd being the service that provides the
+// aux component implementations.
+func (g *LightningTerminal) buildAuxComponents() (*lnd.AuxComponents, error) {
+	errNotAvailable := fmt.Errorf("tapd is not available, both lnd and " +
+		"tapd must be started in integrated mode for Taproot " +
+		"Assets Channels to be available")
+
+	tapdWrapper, available := g.subServerMgr.GetServer(subservers.TAP)
+	if !available {
+		return nil, errNotAvailable
+	}
+
+	if tapdWrapper.Remote() {
+		return nil, errNotAvailable
+	}
+
+	tapdOpt := tapdWrapper.Impl()
+	tapdAny, err := tapdOpt.UnwrapOrErr(errors.New("tapd not available"))
+	if err != nil {
+		return nil, err
+	}
+
+	tapd, ok := tapdAny.(*taprootassets.Server)
+	if !ok {
+		return nil, fmt.Errorf("tapd is not of the expected type")
+	}
+
+	router := msgmux.NewMultiMsgRouter()
+	router.Start()
+	err = router.RegisterEndpoint(tapd)
+	if err != nil {
+		return nil, fmt.Errorf("error registering tapd endpoint: %w",
+			err)
+	}
+
+	return &lnd.AuxComponents{
+		AuxLeafStore: fn.Some[lnwallet.AuxLeafStore](tapd),
+		MsgRouter:    fn.Some[msgmux.Router](router),
+		AuxFundingController: fn.Some[funding.AuxFundingController](
+			tapd,
+		),
+		AuxSigner:     fn.Some[lnwallet.AuxSigner](tapd),
+		TrafficShaper: fn.Some[routing.TlvTrafficShaper](tapd),
+		AuxDataParser: fn.Some[lnd.AuxDataParser](tapd),
+		AuxChanCloser: fn.Some[chancloser.AuxChanCloser](tapd),
+		AuxSweeper:    fn.Some[sweep.AuxSweeper](tapd),
+		AuxContractResolver: fn.Some[lnwallet.AuxContractResolver](
+			tapd,
+		),
+	}, nil
+}
+
 // shutdownSubServers stops all subservers that were started and attached to
 // lnd.
 func (g *LightningTerminal) shutdownSubServers() error {