Merge pull request #9072 from lightningnetwork/extract-part3-from-staging-branch

[custom channels 3/5]: Extract PART3 from mega staging branch

funding/aux_funding.go

@@ -0,0 +1,51 @@
+package funding
+
+import (
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/lightningnetwork/lnd/msgmux"
+)
+
+// AuxFundingDescResult is a type alias for a function that returns an optional
+// aux funding desc.
+type AuxFundingDescResult = fn.Result[fn.Option[lnwallet.AuxFundingDesc]]
+
+// AuxTapscriptResult is a type alias for a function that returns an optional
+// tapscript root.
+type AuxTapscriptResult = fn.Result[fn.Option[chainhash.Hash]]
+
+// AuxFundingController permits the implementation of the funding of custom
+// channels types. The controller serves as a MsgEndpoint which allows it to
+// intercept custom messages, or even the regular funding messages. The
+// controller might also pass along an aux funding desc based on an existing
+// pending channel ID.
+type AuxFundingController interface {
+	// Endpoint is the embedded interface that signals that the funding
+	// controller is also a message endpoint. This'll allow it to handle
+	// custom messages specific to the funding type.
+	msgmux.Endpoint
+
+	// 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.
+	DescFromPendingChanID(pid PendingChanID, openChan lnwallet.AuxChanState,
+		keyRing lntypes.Dual[lnwallet.CommitmentKeyRing],
+		initiator bool) AuxFundingDescResult
+
+	// 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) AuxTapscriptResult
+
+	// ChannelReady is called when a channel has been fully opened (multiple
+	// confirmations) and is ready to be used. This can be used to perform
+	// any final setup or cleanup.
+	ChannelReady(openChan lnwallet.AuxChanState) error
+
+	// ChannelFinalized is called when a channel has been fully finalized.
+	// In this state, we've received the commitment sig from the remote
+	// party, so we are safe to broadcast the funding transaction.
+	ChannelFinalized(PendingChanID) error
+}

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
@@ -549,6 +548,16 @@ type Config struct {
 	// AuxLeafStore is an optional store that can be used to store auxiliary
 	// leaves for certain custom channel types.
 	AuxLeafStore fn.Option[lnwallet.AuxLeafStore]
+
+	// AuxFundingController is an optional controller that can be used to
+	// modify the way we handle certain custom channel types. It's also
+	// able to automatically handle new custom protocol messages related to
+	// the funding process.
+	AuxFundingController fn.Option[AuxFundingController]
+
+	// AuxSigner is an optional signer that can be used to sign auxiliary
+	// leaves for certain custom channel types.
+	AuxSigner fn.Option[lnwallet.AuxSigner]
 }
 
 // Manager acts as an orchestrator/bridge between the wallet's
@@ -1078,6 +1087,9 @@ func (f *Manager) advanceFundingState(channel *channeldb.OpenChannel,
 	f.cfg.AuxLeafStore.WhenSome(func(s lnwallet.AuxLeafStore) {
 		chanOpts = append(chanOpts, lnwallet.WithLeafStore(s))
 	})
+	f.cfg.AuxSigner.WhenSome(func(s lnwallet.AuxSigner) {
+		chanOpts = append(chanOpts, lnwallet.WithAuxSigner(s))
+	})
 
 	// We create the state-machine object which wraps the database state.
 	lnChannel, err := lnwallet.NewLightningChannel(
@@ -1256,8 +1268,8 @@ func (f *Manager) stateStep(channel *channeldb.OpenChannel,
 
 // advancePendingChannelState waits for a pending channel's funding tx to
 // confirm, and marks it open in the database when that happens.
-func (f *Manager) advancePendingChannelState(
-	channel *channeldb.OpenChannel, pendingChanID PendingChanID) error {
+func (f *Manager) advancePendingChannelState(channel *channeldb.OpenChannel,
+	pendingChanID PendingChanID) error {
 
 	if channel.IsZeroConf() {
 		// Persist the alias to the alias database.
@@ -1626,6 +1638,23 @@ func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
 		return
 	}
 
+	// 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
+	// MuSig funding output.
+	tapscriptRoot, err := fn.MapOptionZ(
+		f.cfg.AuxFundingController,
+		func(c AuxFundingController) AuxTapscriptResult {
+			return c.DeriveTapscriptRoot(msg.PendingChannelID)
+		},
+	).Unpack()
+	if err != nil {
+		err = fmt.Errorf("error deriving tapscript root: %w", err)
+		log.Error(err)
+		f.failFundingFlow(peer, cid, err)
+
+		return
+	}
+
 	req := &lnwallet.InitFundingReserveMsg{
 		ChainHash:        &msg.ChainHash,
 		PendingChanID:    msg.PendingChannelID,
@@ -1642,6 +1671,7 @@ func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
 		ZeroConf:         zeroConf,
 		OptionScidAlias:  scid,
 		ScidAliasFeature: scidFeatureVal,
+		TapscriptRoot:    tapscriptRoot,
 	}
 
 	reservation, err := f.cfg.Wallet.InitChannelReservation(req)
@@ -1898,6 +1928,8 @@ func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
 	log.Debugf("Remote party accepted commitment rendering params: %v",
 		lnutils.SpewLogClosure(params))
 
+	reservation.SetState(lnwallet.SentAcceptChannel)
+
 	// With the initiator's contribution recorded, respond with our
 	// contribution in the next message of the workflow.
 	fundingAccept := lnwire.AcceptChannel{
@@ -1958,6 +1990,10 @@ func (f *Manager) funderProcessAcceptChannel(peer lnpeer.Peer,
 	// Update the timestamp once the fundingAcceptMsg has been handled.
 	defer resCtx.updateTimestamp()
 
+	if resCtx.reservation.State() != lnwallet.SentOpenChannel {
+		return
+	}
+
 	log.Infof("Recv'd fundingResponse for pending_id(%x)",
 		pendingChanID[:])
 
@@ -2261,10 +2297,34 @@ 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.
+		auxFundingDesc, err := fn.MapOptionZ(
+			f.cfg.AuxFundingController,
+			func(c AuxFundingController) AuxFundingDescResult {
+				return c.DescFromPendingChanID(
+					cid.tempChanID,
+					lnwallet.NewAuxChanState(
+						resCtx.reservation.ChanState(),
+					),
+					resCtx.reservation.CommitmentKeyRings(),
+					true,
+				)
+			},
+		).Unpack()
+		if err != nil {
+			failFlow("error continuing PSBT flow", err)
+			return
+		}
+
 		// 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(auxFundingDesc)
 		if err != nil {
 			failFlow("error continuing PSBT flow", err)
 			return
@@ -2359,6 +2419,8 @@ func (f *Manager) continueFundingAccept(resCtx *reservationWithCtx,
 		}
 	}
 
+	resCtx.reservation.SetState(lnwallet.SentFundingCreated)
+
 	if err := resCtx.peer.SendMessage(true, fundingCreated); err != nil {
 		log.Errorf("Unable to send funding complete message: %v", err)
 		f.failFundingFlow(resCtx.peer, cid, err)
@@ -2390,11 +2452,14 @@ 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)
 
+	if resCtx.reservation.State() != lnwallet.SentAcceptChannel {
+		return
+	}
+
 	// Create the channel identifier without setting the active channel ID.
 	cid := newChanIdentifier(pendingChanID)
 
@@ -2422,16 +2487,38 @@ 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.
+	auxFundingDesc, err := fn.MapOptionZ(
+		f.cfg.AuxFundingController,
+		func(c AuxFundingController) AuxFundingDescResult {
+			return c.DescFromPendingChanID(
+				cid.tempChanID, lnwallet.NewAuxChanState(
+					resCtx.reservation.ChanState(),
+				), resCtx.reservation.CommitmentKeyRings(),
+				true,
+			)
+		},
+	).Unpack()
+	if err != nil {
+		log.Errorf("error continuing PSBT flow: %v", err)
+		f.failFundingFlow(peer, cid, err)
+		return
+	}
+
 	// 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 AuxFunding controller as well,
+	// which may be used by the reservation system to finalize funding our
+	// side.
 	completeChan, err := resCtx.reservation.CompleteReservationSingle(
-		&fundingOut, commitSig,
+		&fundingOut, commitSig, 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
@@ -2632,6 +2719,14 @@ func (f *Manager) funderProcessFundingSigned(peer lnpeer.Peer,
 		return
 	}
 
+	if resCtx.reservation.State() != lnwallet.SentFundingCreated {
+		err := fmt.Errorf("unable to find reservation for chan_id=%x",
+			msg.ChanID)
+		f.failFundingFlow(peer, cid, err)
+
+		return
+	}
+
 	// Create an entry in the local discovery map so we can ensure that we
 	// process the channel confirmation fully before we receive a
 	// channel_ready message.
@@ -2727,6 +2822,21 @@ func (f *Manager) funderProcessFundingSigned(peer lnpeer.Peer,
 		}
 	}
 
+	// Before we proceed, if we have a funding hook that wants a
+	// notification that it's safe to broadcast the funding transaction,
+	// then we'll send that now.
+	err = fn.MapOptionZ(
+		f.cfg.AuxFundingController,
+		func(controller AuxFundingController) error {
+			return controller.ChannelFinalized(cid.tempChanID)
+		},
+	)
+	if err != nil {
+		log.Errorf("Failed to inform aux funding controller about "+
+			"ChannelPoint(%v) being finalized: %v", fundingPoint,
+			err)
+	}
+
 	// Now that we have a finalized reservation for this funding flow,
 	// we'll send the to be active channel to the ChainArbitrator so it can
 	// watch for any on-chain actions before the channel has fully
@@ -2742,9 +2852,6 @@ 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{
@@ -3450,6 +3557,7 @@ func (f *Manager) addToGraph(completeChan *channeldb.OpenChannel,
 	errChan := f.cfg.SendAnnouncement(
 		ann.chanAnn, discovery.ChannelCapacity(completeChan.Capacity),
 		discovery.ChannelPoint(completeChan.FundingOutpoint),
+		discovery.TapscriptRoot(completeChan.TapscriptRoot),
 	)
 	select {
 	case err := <-errChan:
@@ -3646,7 +3754,7 @@ func (f *Manager) annAfterSixConfs(completeChan *channeldb.OpenChannel,
 
 // waitForZeroConfChannel is called when the state is addedToGraph with
 // a zero-conf channel. This will wait for the real confirmation, add the
-// confirmed SCID to the graph, and then announce after six confs.
+// confirmed SCID to the router graph, and then announce after six confs.
 func (f *Manager) waitForZeroConfChannel(c *channeldb.OpenChannel) error {
 	// First we'll check whether the channel is confirmed on-chain. If it
 	// is already confirmed, the chainntnfs subsystem will return with the
@@ -3977,6 +4085,26 @@ func (f *Manager) handleChannelReady(peer lnpeer.Peer, //nolint:funlen
 				PubNonce: remoteNonce,
 			}),
 		)
+
+		// Inform the aux funding controller that the liquidity in the
+		// custom channel is now ready to be advertised. We potentially
+		// haven't sent our own channel ready message yet, but other
+		// than that the channel is ready to count toward available
+		// liquidity.
+		err = fn.MapOptionZ(
+			f.cfg.AuxFundingController,
+			func(controller AuxFundingController) error {
+				return controller.ChannelReady(
+					lnwallet.NewAuxChanState(channel),
+				)
+			},
+		)
+		if err != nil {
+			cid := newChanIdentifier(msg.ChanID)
+			f.sendWarning(peer, cid, err)
+
+			return
+		}
 	}
 
 	// The channel_ready message contains the next commitment point we'll
@@ -4063,6 +4191,19 @@ func (f *Manager) handleChannelReadyReceived(channel *channeldb.OpenChannel,
 	log.Debugf("Channel(%v) with ShortChanID %v: successfully "+
 		"added to graph", chanID, scid)
 
+	err = fn.MapOptionZ(
+		f.cfg.AuxFundingController,
+		func(controller AuxFundingController) error {
+			return controller.ChannelReady(
+				lnwallet.NewAuxChanState(channel),
+			)
+		},
+	)
+	if err != nil {
+		return fmt.Errorf("failed notifying aux funding controller "+
+			"about channel ready: %w", err)
+	}
+
 	// Give the caller a final update notifying them that the channel is
 	fundingPoint := channel.FundingOutpoint
 	cp := &lnrpc.ChannelPoint{
@@ -4376,9 +4517,9 @@ func (f *Manager) announceChannel(localIDKey, remoteIDKey *btcec.PublicKey,
 	//
 	// We can pass in zeroes for the min and max htlc policy, because we
 	// only use the channel announcement message from the returned struct.
-	ann, err := f.newChanAnnouncement(localIDKey, remoteIDKey,
-		localFundingKey, remoteFundingKey, shortChanID, chanID,
-		0, 0, nil, chanType,
+	ann, err := f.newChanAnnouncement(
+		localIDKey, remoteIDKey, localFundingKey, remoteFundingKey,
+		shortChanID, chanID, 0, 0, nil, chanType,
 	)
 	if err != nil {
 		log.Errorf("can't generate channel announcement: %v", err)
@@ -4444,7 +4585,6 @@ 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
 }
@@ -4634,6 +4774,23 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
 		scidFeatureVal = true
 	}
 
+	// 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, err := fn.MapOptionZ(
+		f.cfg.AuxFundingController,
+		func(c AuxFundingController) AuxTapscriptResult {
+			return c.DeriveTapscriptRoot(chanID)
+		},
+	).Unpack()
+	if err != nil {
+		err = fmt.Errorf("error deriving tapscript root: %w", err)
+		log.Error(err)
+		msg.Err <- err
+
+		return
+	}
+
 	req := &lnwallet.InitFundingReserveMsg{
 		ChainHash:         &msg.ChainHash,
 		PendingChanID:     chanID,
@@ -4673,6 +4830,7 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
 		OptionScidAlias:  scid,
 		ScidAliasFeature: scidFeatureVal,
 		Memo:             msg.Memo,
+		TapscriptRoot:    tapscriptRoot,
 	}
 
 	reservation, err := f.cfg.Wallet.InitChannelReservation(req)
@@ -4824,6 +4982,8 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
 	log.Infof("Starting funding workflow with %v for pending_id(%x), "+
 		"committype=%v", msg.Peer.Address(), chanID, commitType)
 
+	reservation.SetState(lnwallet.SentOpenChannel)
+
 	fundingOpen := lnwire.OpenChannel{
 		ChainHash:             *f.cfg.Wallet.Cfg.NetParams.GenesisHash,
 		PendingChannelID:      chanID,

funding/manager_test.go

@@ -567,6 +567,9 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 		AuxLeafStore: fn.Some[lnwallet.AuxLeafStore](
 			&lnwallet.MockAuxLeafStore{},
 		),
+		AuxSigner: fn.Some[lnwallet.AuxSigner](
+			&lnwallet.MockAuxSigner{},
+		),
 	}
 
 	for _, op := range options {
@@ -677,6 +680,7 @@ func recreateAliceFundingManager(t *testing.T, alice *testNode) {
 		DeleteAliasEdge:       oldCfg.DeleteAliasEdge,
 		AliasManager:          oldCfg.AliasManager,
 		AuxLeafStore:          oldCfg.AuxLeafStore,
+		AuxSigner:             oldCfg.AuxSigner,
 	})
 	require.NoError(t, err, "failed recreating aliceFundingManager")