funding+lnwallet: finish hook up new aux funding flow

For the initiator, once we get the signal that the PSBT has been
finalized, we'll call into the aux funder to get the funding desc. For
the responder, once we receive the funding_created message, we'll do the
same.

We now also have local+remote aux leaves for the commitment transaction.

Author: Roasbeef

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"
@@ -20,10 +21,10 @@ type AuxFundingController interface {
 	// DescPendingChanID 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(pid PendingChanID,
+		openChan *channeldb.OpenChannel,
+		localKeyRing, remoteKeyRing lnwallet.CommitmentKeyRing,
+		initiator bool) fn.Option[lnwallet.AuxFundingDesc]
 
 	// DeriveTapscriptRoot takes a pending channel ID and maybe returns a
 	// tapscript root that should be used when creating any musig2 sessions

funding/manager.go

@@ -99,7 +99,6 @@ const (
 	// you and limitless channel size (apart from 21 million cap).
 	MaxBtcFundingAmountWumbo = btcutil.Amount(1000000000)
 
-	// TODO(roasbeef): tune.
 	msgBufferSize = 50
 
 	// MaxWaitNumBlocksFundingConf is the maximum number of blocks to wait
@@ -2232,10 +2231,29 @@ func (f *Manager) waitForPsbt(intent *chanfunding.PsbtIntent,
 			return
 		}
 
+		// At this point, we'll see if there's an AuxFundingDesc we
+		// need to deliver so the funding process can continue
+		// properly.
+		chanState := resCtx.reservation.ChanState()
+		localKeys, remoteKeys := resCtx.reservation.CommitmentKeyRings()
+		auxFundingDesc := fn.MapOption(
+			func(a AuxFundingController) fn.Option[lnwallet.AuxFundingDesc] {
+				return a.DescFromPendingChanID(
+					cid.tempChanID, chanState, *localKeys,
+					*remoteKeys, true,
+				)
+			},
+		)(f.cfg.AuxFundingController)
+
 		// A non-nil error means we can continue the funding flow.
 		// Notify the wallet so it can prepare everything we need to
 		// continue.
-		err = resCtx.reservation.ProcessPsbt()
+		//
+		// We'll also pass along the aux funding controller as well,
+		// which may be used to help process the finalized PSBT.
+		err = resCtx.reservation.ProcessPsbt(
+			fn.FlattenOption(auxFundingDesc),
+		)
 		if err != nil {
 			failFlow("error continuing PSBT flow", err)
 			return
@@ -2299,6 +2317,10 @@ func (f *Manager) continueFundingAccept(resCtx *reservationWithCtx,
 	// funding flow fails.
 	cid.setChanID(channelID)
 
+	// Now that we're ready to resume the funding flow, we'll call into the
+	// aux controller with the final funding details so we can obtain the
+	// funding descs we need.
+
 	// Send the FundingCreated msg.
 	fundingCreated := &lnwire.FundingCreated{
 		PendingChannelID: cid.tempChanID,
@@ -2361,7 +2383,6 @@ func (f *Manager) fundeeProcessFundingCreated(peer lnpeer.Peer,
 	// final funding transaction, as well as a signature for our version of
 	// the commitment transaction. So at this point, we can validate the
 	// initiator's commitment transaction, then send our own if it's valid.
-	// TODO(roasbeef): make case (p vs P) consistent throughout
 	fundingOut := msg.FundingPoint
 	log.Infof("completing pending_id(%x) with ChannelPoint(%v)",
 		pendingChanID[:], fundingOut)
@@ -2393,16 +2414,32 @@ func (f *Manager) fundeeProcessFundingCreated(peer lnpeer.Peer,
 		}
 	}
 
+	// At this point, we'll see if there's an AuxFundingDesc we need to
+	// deliver so the funding process can continue properly.
+	chanState := resCtx.reservation.ChanState()
+	localKeys, remoteKeys := resCtx.reservation.CommitmentKeyRings()
+	auxFundingDesc := fn.MapOption(
+		func(a AuxFundingController) fn.Option[lnwallet.AuxFundingDesc] {
+			return a.DescFromPendingChanID(
+				cid.tempChanID, chanState, *localKeys,
+				*remoteKeys, true,
+			)
+		},
+	)(f.cfg.AuxFundingController)
+
 	// With all the necessary data available, attempt to advance the
 	// funding workflow to the next stage. If this succeeds then the
 	// funding transaction will broadcast after our next message.
 	// CompleteReservationSingle will also mark the channel as 'IsPending'
 	// in the database.
+	//
+	// We'll also directly pass in the AuxFundiner controller as well,
+	// which may be used by the reservation system to finalize funding our
+	// our side.
 	completeChan, err := resCtx.reservation.CompleteReservationSingle(
-		&fundingOut, commitSig,
+		&fundingOut, commitSig, fn.FlattenOption(auxFundingDesc),
 	)
 	if err != nil {
-		// TODO(roasbeef): better error logging: peerID, channelID, etc.
 		log.Errorf("unable to complete single reservation: %v", err)
 		f.failFundingFlow(peer, cid, err)
 		return
@@ -2713,9 +2750,6 @@ func (f *Manager) funderProcessFundingSigned(peer lnpeer.Peer,
 
 	// Send an update to the upstream client that the negotiation process
 	// is over.
-	//
-	// TODO(roasbeef): add abstraction over updates to accommodate
-	// long-polling, or SSE, etc.
 	upd := &lnrpc.OpenStatusUpdate{
 		Update: &lnrpc.OpenStatusUpdate_ChanPending{
 			ChanPending: &lnrpc.PendingUpdate{
@@ -4420,7 +4454,6 @@ func (f *Manager) announceChannel(localIDKey, remoteIDKey *btcec.PublicKey,
 
 // InitFundingWorkflow sends a message to the funding manager instructing it
 // to initiate a single funder workflow with the source peer.
-// TODO(roasbeef): re-visit blocking nature..
 func (f *Manager) InitFundingWorkflow(msg *InitFundingMsg) {
 	f.fundingRequests <- msg
 }

lnwallet/reservation.go

@@ -612,12 +612,15 @@ func (r *ChannelReservation) IsCannedShim() bool {
 }
 
 // ProcessPsbt continues a previously paused funding flow that involves PSBT to
-// construct the funding transaction. This method can be called once the PSBT is
-// finalized and the signed transaction is available.
-func (r *ChannelReservation) ProcessPsbt() error {
+// construct the funding transaction. This method can be called once the PSBT
+// is finalized and the signed transaction is available.
+func (r *ChannelReservation) ProcessPsbt(
+	auxFundingDesc fn.Option[AuxFundingDesc]) error {
+
 	errChan := make(chan error, 1)
 
 	r.wallet.msgChan <- &continueContributionMsg{
+		auxFundingDesc:   auxFundingDesc,
 		pendingFundingID: r.reservationID,
 		err:              errChan,
 	}
@@ -719,8 +722,10 @@ func (r *ChannelReservation) CompleteReservation(fundingInputScripts []*input.Sc
 // available via the .OurSignatures() method. As this method should only be
 // called as a response to a single funder channel, only a commitment signature
 // will be populated.
-func (r *ChannelReservation) CompleteReservationSingle(fundingPoint *wire.OutPoint,
-	commitSig input.Signature) (*channeldb.OpenChannel, error) {
+func (r *ChannelReservation) CompleteReservationSingle(
+	fundingPoint *wire.OutPoint, commitSig input.Signature,
+	auxFundingDesc fn.Option[AuxFundingDesc],
+) (*channeldb.OpenChannel, error) {
 
 	errChan := make(chan error, 1)
 	completeChan := make(chan *channeldb.OpenChannel, 1)
@@ -730,6 +735,7 @@ func (r *ChannelReservation) CompleteReservationSingle(fundingPoint *wire.OutPoi
 		fundingOutpoint:    fundingPoint,
 		theirCommitmentSig: commitSig,
 		completeChan:       completeChan,
+		auxFundingDesc:     auxFundingDesc,
 		err:                errChan,
 	}
 
@@ -815,6 +821,36 @@ func (r *ChannelReservation) Cancel() error {
 	return <-errChan
 }
 
+// ChanState the current open channel state.
+func (r *ChannelReservation) ChanState() *channeldb.OpenChannel {
+	r.RLock()
+	defer r.RUnlock()
+	return r.partialState
+}
+
+// CommitmentKeyRings returns the local+remote key ring used for the very first
+// commitment transaction both parties.
+func (r *ChannelReservation) CommitmentKeyRings() (*CommitmentKeyRing, *CommitmentKeyRing) {
+	r.RLock()
+	defer r.RUnlock()
+
+	chanType := r.partialState.ChanType
+	ourChanCfg := r.ourContribution.ChannelConfig
+	theirChanCfg := r.theirContribution.ChannelConfig
+
+	localKeys := DeriveCommitmentKeys(
+		r.ourContribution.FirstCommitmentPoint, true, chanType,
+		ourChanCfg, theirChanCfg,
+	)
+
+	remoteKeys := DeriveCommitmentKeys(
+		r.theirContribution.FirstCommitmentPoint, false, chanType,
+		ourChanCfg, theirChanCfg,
+	)
+
+	return localKeys, remoteKeys
+}
+
 // VerifyConstraints is a helper function that can be used to check the sanity
 // of various channel constraints.
 func VerifyConstraints(c *channeldb.ChannelConstraints,

lnwallet/wallet.go

@@ -280,6 +280,8 @@ type addContributionMsg struct {
 type continueContributionMsg struct {
 	pendingFundingID uint64
 
+	auxFundingDesc fn.Option[AuxFundingDesc]
+
 	// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
 	err chan error
 }
@@ -335,6 +337,8 @@ type addCounterPartySigsMsg struct {
 type addSingleFunderSigsMsg struct {
 	pendingFundingID uint64
 
+	auxFundingDesc fn.Option[AuxFundingDesc]
+
 	// fundingOutpoint is the outpoint of the completed funding
 	// transaction as assembled by the workflow initiator.
 	fundingOutpoint *wire.OutPoint
@@ -1475,7 +1479,8 @@ func (l *LightningWallet) handleFundingCancelRequest(req *fundingReserveCancelMs
 // createCommitOpts is a struct that holds the options for creating a a new
 // commitment transaction.
 type createCommitOpts struct {
-	auxLeaves fn.Option[CommitAuxLeaves]
+	localAuxLeaves  fn.Option[CommitAuxLeaves]
+	remoteAuxLeaves fn.Option[CommitAuxLeaves]
 }
 
 // defaultCommitOpts returns a new createCommitOpts with default values.
@@ -1485,11 +1490,12 @@ func defaultCommitOpts() createCommitOpts {
 
 // WithAuxLeaves is a functional option that can be used to set the aux leaves
 // for a new commitment transaction.
-//
-// TODO(roasbeef): local+remote  leaves
-func WithAuxLeaves(leaves fn.Option[CommitAuxLeaves]) CreateCommitOpt {
+func WithAuxLeaves(localLeaves, remoteLeaves fn.Option[CommitAuxLeaves],
+) CreateCommitOpt {
+
 	return func(o *createCommitOpts) {
-		o.auxLeaves = leaves
+		o.localAuxLeaves = localLeaves
+		o.remoteAuxLeaves = remoteLeaves
 	}
 }
 
@@ -1523,7 +1529,7 @@ func CreateCommitmentTxns(localBalance, remoteBalance btcutil.Amount,
 	ourCommitTx, err := CreateCommitTx(
 		chanType, fundingTxIn, localCommitmentKeys, ourChanCfg,
 		theirChanCfg, localBalance, remoteBalance, 0, initiator,
-		leaseExpiry, options.auxLeaves,
+		leaseExpiry, options.localAuxLeaves,
 	)
 	if err != nil {
 		return nil, nil, err
@@ -1537,7 +1543,7 @@ func CreateCommitmentTxns(localBalance, remoteBalance btcutil.Amount,
 	theirCommitTx, err := CreateCommitTx(
 		chanType, fundingTxIn, remoteCommitmentKeys, theirChanCfg,
 		ourChanCfg, remoteBalance, localBalance, 0, !initiator,
-		leaseExpiry, options.auxLeaves,
+		leaseExpiry, options.remoteAuxLeaves,
 	)
 	if err != nil {
 		return nil, nil, err
@@ -1816,6 +1822,24 @@ func (l *LightningWallet) handleChanPointReady(req *continueContributionMsg) {
 		return
 	}
 
+	chanState := pendingReservation.partialState
+
+	// If we have an aux funding desc, then we can use it to populate some
+	// of the optional, but opaque TLV blobs we'll carry for the channel.
+	chanState.CustomBlob = fn.MapOption(func(desc AuxFundingDesc) tlv.Blob {
+		return desc.CustomFundingBlob
+	})(req.auxFundingDesc)
+	chanState.LocalCommitment.CustomBlob = fn.MapOption(
+		func(desc AuxFundingDesc) tlv.Blob {
+			return desc.CustomLocalCommitBlob
+		},
+	)(req.auxFundingDesc)
+	chanState.RemoteCommitment.CustomBlob = fn.MapOption(
+		func(desc AuxFundingDesc) tlv.Blob {
+			return desc.CustomRemoteCommitBlob
+		},
+	)(req.auxFundingDesc)
+
 	ourContribution := pendingReservation.ourContribution
 	theirContribution := pendingReservation.theirContribution
 	chanPoint := pendingReservation.partialState.FundingOutpoint
@@ -1874,7 +1898,6 @@ func (l *LightningWallet) handleChanPointReady(req *continueContributionMsg) {
 	// Store their current commitment point. We'll need this after the
 	// first state transition in order to verify the authenticity of the
 	// revocation.
-	chanState := pendingReservation.partialState
 	chanState.RemoteCurrentRevocation = theirContribution.FirstCommitmentPoint
 
 	// Create the txin to our commitment transaction; required to construct
@@ -1891,14 +1914,21 @@ func (l *LightningWallet) handleChanPointReady(req *continueContributionMsg) {
 		leaseExpiry = pendingReservation.partialState.ThawHeight
 	}
 
+	localAuxLeaves := fn.MapOption(func(desc AuxFundingDesc) CommitAuxLeaves {
+		return desc.LocalInitAuxLeaves
+	})(req.auxFundingDesc)
+	remoteAuxLeaves := fn.MapOption(func(desc AuxFundingDesc) CommitAuxLeaves {
+		return desc.RemoteInitAuxLeaves
+	})(req.auxFundingDesc)
+
 	ourCommitTx, theirCommitTx, err := CreateCommitmentTxns(
 		localBalance, remoteBalance, ourContribution.ChannelConfig,
 		theirContribution.ChannelConfig,
 		ourContribution.FirstCommitmentPoint,
 		theirContribution.FirstCommitmentPoint, fundingTxIn,
 		pendingReservation.partialState.ChanType,
 		pendingReservation.partialState.IsInitiator, leaseExpiry,
-		WithAuxLeaves(pendingReservation.initAuxLeaves),
+		WithAuxLeaves(localAuxLeaves, remoteAuxLeaves),
 	)
 	if err != nil {
 		req.err <- err
@@ -2314,11 +2344,24 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	pendingReservation.Lock()
 	defer pendingReservation.Unlock()
 
-	// TODO(roasbeef): get funding desc
-	//  * set all blobs
-	//  * get the local+remote commitAux leaves for below commitment txns
-
 	chanState := pendingReservation.partialState
+
+	// If we have an aux funding desc, then we can use it to populate some
+	// of the optional, but opaque TLV blobs we'll carry for the channel.
+	chanState.CustomBlob = fn.MapOption(func(desc AuxFundingDesc) tlv.Blob {
+		return desc.CustomFundingBlob
+	})(req.auxFundingDesc)
+	chanState.LocalCommitment.CustomBlob = fn.MapOption(
+		func(desc AuxFundingDesc) tlv.Blob {
+			return desc.CustomLocalCommitBlob
+		},
+	)(req.auxFundingDesc)
+	chanState.RemoteCommitment.CustomBlob = fn.MapOption(
+		func(desc AuxFundingDesc) tlv.Blob {
+			return desc.CustomRemoteCommitBlob
+		},
+	)(req.auxFundingDesc)
+
 	chanType := pendingReservation.partialState.ChanType
 	chanState.FundingOutpoint = *req.fundingOutpoint
 	fundingTxIn := wire.NewTxIn(req.fundingOutpoint, nil, nil)
@@ -2332,6 +2375,14 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	if pendingReservation.partialState.ChanType.HasLeaseExpiration() {
 		leaseExpiry = pendingReservation.partialState.ThawHeight
 	}
+
+	localAuxLeaves := fn.MapOption(func(desc AuxFundingDesc) CommitAuxLeaves {
+		return desc.LocalInitAuxLeaves
+	})(req.auxFundingDesc)
+	remoteAuxLeaves := fn.MapOption(func(desc AuxFundingDesc) CommitAuxLeaves {
+		return desc.RemoteInitAuxLeaves
+	})(req.auxFundingDesc)
+
 	ourCommitTx, theirCommitTx, err := CreateCommitmentTxns(
 		localBalance, remoteBalance,
 		pendingReservation.ourContribution.ChannelConfig,
@@ -2340,7 +2391,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 		pendingReservation.theirContribution.FirstCommitmentPoint,
 		*fundingTxIn, chanType,
 		pendingReservation.partialState.IsInitiator, leaseExpiry,
-		WithAuxLeaves(pendingReservation.initAuxLeaves),
+		WithAuxLeaves(localAuxLeaves, remoteAuxLeaves),
 	)
 	if err != nil {
 		req.err <- err