lnwallet: add error to aux funding controller

Author: guggero

funding/aux_funding.go

@@ -2,6 +2,7 @@ package funding
 
 import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/protofsm"
@@ -17,16 +18,45 @@ type AuxFundingController interface {
 	// handle custom messages specific to the funding type.
 	protofsm.MsgEndpoint
 
-	// DescPendingChanID takes a pending channel ID, that may already be
+	// DescFromPendingChanID takes a pending channel ID, that may already be
 	// known due to prior custom channel messages, and maybe returns an aux
 	// funding desc which can be used to modify how a channel is funded.
-	//
-	// TODO(roasbeef): erorr on validation if fail due to invalid root
-	// match?
-	DescFromPendingChanID(PendingChanID) fn.Option[lnwallet.AuxFundingDesc]
+	DescFromPendingChanID(PendingChanID,
+		*channeldb.OpenChannel, lnwallet.CommitmentKeyRing,
+		bool) (fn.Option[lnwallet.AuxFundingDesc], error)
 
 	// DeriveTapscriptRoot takes a pending channel ID and maybe returns a
 	// tapscript root that should be used when creating any musig2 sessions
 	// for a channel.
-	DeriveTapscriptRoot(PendingChanID) fn.Option[chainhash.Hash]
+	DeriveTapscriptRoot(PendingChanID) (fn.Option[chainhash.Hash], error)
+}
+
+// descFromPendingChanID takes a pending channel ID, that may already be
+// known due to prior custom channel messages, and maybe returns an aux
+// funding desc which can be used to modify how a channel is funded.
+func descFromPendingChanID(controller fn.Option[AuxFundingController],
+	chanID PendingChanID, openChan *channeldb.OpenChannel,
+	keyRing lnwallet.CommitmentKeyRing,
+	initiator bool) (fn.Option[lnwallet.AuxFundingDesc], error) {
+
+	if controller.IsNone() {
+		return fn.None[lnwallet.AuxFundingDesc](), nil
+	}
+
+	return controller.UnsafeFromSome().DescFromPendingChanID(
+		chanID, openChan, keyRing, initiator,
+	)
+}
+
+// deriveTapscriptRoot takes a pending channel ID and maybe returns a
+// tapscript root that should be used when creating any musig2 sessions
+// for a channel.
+func deriveTapscriptRoot(controller fn.Option[AuxFundingController],
+	chanID PendingChanID) (fn.Option[chainhash.Hash], error) {
+
+	if controller.IsNone() {
+		return fn.None[chainhash.Hash](), nil
+	}
+
+	return controller.UnsafeFromSome().DeriveTapscriptRoot(chanID)
 }

funding/manager.go

@@ -1631,11 +1631,14 @@ func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
 	// At this point, if we have an AuxFundingController active, we'll
 	// check to see if we have a special tapscript root to use in our
 	// musig2 funding output.
-	tapscriptRoot := fn.MapOption(
-		func(a AuxFundingController) fn.Option[chainhash.Hash] {
-			return a.DeriveTapscriptRoot(msg.PendingChannelID)
-		},
-	)(f.cfg.AuxFundingController)
+	tapscriptRoot, err := deriveTapscriptRoot(
+		f.cfg.AuxFundingController, msg.PendingChannelID,
+	)
+	if err != nil {
+		err = fmt.Errorf("error deriving tapscript root: %w", err)
+		log.Error(err)
+		f.failFundingFlow(peer, cid, err)
+	}
 
 	req := &lnwallet.InitFundingReserveMsg{
 		ChainHash:        &msg.ChainHash,
@@ -1653,7 +1656,7 @@ func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
 		ZeroConf:         zeroConf,
 		OptionScidAlias:  scid,
 		ScidAliasFeature: scidFeatureVal,
-		TapscriptRoot:    fn.FlattenOption(tapscriptRoot),
+		TapscriptRoot:    tapscriptRoot,
 	}
 
 	reservation, err := f.cfg.Wallet.InitChannelReservation(req)
@@ -4631,11 +4634,14 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
 	// At this point, if we have an AuxFundingController active, we'll
 	// check to see if we have a special tapscript root to use in our
 	// musig2 funding output.
-	tapscriptRoot := fn.MapOption(
-		func(a AuxFundingController) fn.Option[chainhash.Hash] {
-			return a.DeriveTapscriptRoot(chanID)
-		},
-	)(f.cfg.AuxFundingController)
+	tapscriptRoot, err := deriveTapscriptRoot(
+		f.cfg.AuxFundingController, chanID,
+	)
+	if err != nil {
+		err = fmt.Errorf("error deriving tapscript root: %w", err)
+		msg.Err <- err
+		return
+	}
 
 	req := &lnwallet.InitFundingReserveMsg{
 		ChainHash:         &msg.ChainHash,
@@ -4660,7 +4666,7 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
 		OptionScidAlias:   scid,
 		ScidAliasFeature:  scidFeatureVal,
 		Memo:              msg.Memo,
-		TapscriptRoot:     fn.FlattenOption(tapscriptRoot),
+		TapscriptRoot:     tapscriptRoot,
 		CustomChannelData: msg.CustomChannelData,
 	}