Merge pull request #8270 from ProofOfKeags/feature/stfu

DynComms [1/n]: Implement Quiescence Protocol

docs/release-notes/release-notes-0.19.0.md

@@ -67,6 +67,10 @@
   signal relay was added. This signal has *no impact* on routing, and
   is deployed experimentally to assist ongoing channel jamming research.
 
+* Add initial support for [quiescence](https://github.com/lightningnetwork/lnd/pull/8270).
+  This is a protocol gadget required for Dynamic Commitments and Splicing that
+  will be added later.
+
 ## Functional Enhancements
 * [Add ability](https://github.com/lightningnetwork/lnd/pull/8998) to paginate 
  wallet transactions.
@@ -216,6 +220,7 @@ The underlying functionality between those two options remain the same.
 * Elle Mouton
 * George Tsagkarelis
 * hieblmi
+* Keagan McClelland
 * Oliver Gugger
 * Pins
 * Viktor Tigerström

feature/default_sets.go

@@ -84,6 +84,10 @@ var defaultSetDesc = setDesc{
 		SetNodeAnn: {}, // N
 		SetInvoice: {}, // 9
 	},
+	lnwire.QuiescenceOptional: {
+		SetInit:    {}, // I
+		SetNodeAnn: {}, // N
+	},
 	lnwire.ShutdownAnySegwitOptional: {
 		SetInit:    {}, // I
 		SetNodeAnn: {}, // N

feature/manager.go

@@ -63,6 +63,9 @@ type Config struct {
 	// NoRouteBlinding unsets route blinding feature bits.
 	NoRouteBlinding bool
 
+	// NoQuiescence unsets quiescence feature bits.
+	NoQuiescence bool
+
 	// NoTaprootOverlay unsets the taproot overlay channel feature bits.
 	NoTaprootOverlay bool
 
@@ -199,6 +202,9 @@ func newManager(cfg Config, desc setDesc) (*Manager, error) {
 			raw.Unset(lnwire.Bolt11BlindedPathsOptional)
 			raw.Unset(lnwire.Bolt11BlindedPathsRequired)
 		}
+		if cfg.NoQuiescence {
+			raw.Unset(lnwire.QuiescenceOptional)
+		}
 		if cfg.NoTaprootOverlay {
 			raw.Unset(lnwire.SimpleTaprootOverlayChansOptional)
 			raw.Unset(lnwire.SimpleTaprootOverlayChansRequired)

go.mod

@@ -36,7 +36,7 @@ require (
 	github.com/lightningnetwork/lightning-onion v1.2.1-0.20240712235311-98bd56499dfb
 	github.com/lightningnetwork/lnd/cert v1.2.2
 	github.com/lightningnetwork/lnd/clock v1.1.1
-	github.com/lightningnetwork/lnd/fn v1.2.3
+	github.com/lightningnetwork/lnd/fn v1.2.5
 	github.com/lightningnetwork/lnd/healthcheck v1.2.6
 	github.com/lightningnetwork/lnd/kvdb v1.4.11
 	github.com/lightningnetwork/lnd/queue v1.1.1

go.sum

@@ -456,8 +456,8 @@ github.com/lightningnetwork/lnd/cert v1.2.2 h1:71YK6hogeJtxSxw2teq3eGeuy4rHGKcFf
 github.com/lightningnetwork/lnd/cert v1.2.2/go.mod h1:jQmFn/Ez4zhDgq2hnYSw8r35bqGVxViXhX6Cd7HXM6U=
 github.com/lightningnetwork/lnd/clock v1.1.1 h1:OfR3/zcJd2RhH0RU+zX/77c0ZiOnIMsDIBjgjWdZgA0=
 github.com/lightningnetwork/lnd/clock v1.1.1/go.mod h1:mGnAhPyjYZQJmebS7aevElXKTFDuO+uNFFfMXK1W8xQ=
-github.com/lightningnetwork/lnd/fn v1.2.3 h1:Q1OrgNSgQynVheBNa16CsKVov1JI5N2AR6G07x9Mles=
-github.com/lightningnetwork/lnd/fn v1.2.3/go.mod h1:SyFohpVrARPKH3XVAJZlXdVe+IwMYc4OMAvrDY32kw0=
+github.com/lightningnetwork/lnd/fn v1.2.5 h1:pGMz0BDUxrhvOtShD4FIysdVy+ulfFAnFvTKjZO5Pp8=
+github.com/lightningnetwork/lnd/fn v1.2.5/go.mod h1:SyFohpVrARPKH3XVAJZlXdVe+IwMYc4OMAvrDY32kw0=
 github.com/lightningnetwork/lnd/healthcheck v1.2.6 h1:1sWhqr93GdkWy4+6U7JxBfcyZIE78MhIHTJZfPx7qqI=
 github.com/lightningnetwork/lnd/healthcheck v1.2.6/go.mod h1:Mu02um4CWY/zdTOvFje7WJgJcHyX2zq/FG3MhOAiGaQ=
 github.com/lightningnetwork/lnd/kvdb v1.4.11 h1:fk1HMVFrsVK3xqU7q+JWHRgBltw/a2qIg1E3zazMb/8=

htlcswitch/interfaces.go

@@ -170,6 +170,18 @@ type ChannelUpdateHandler interface {
 	// will only ever be called once. If no CommitSig is owed in the
 	// argument's LinkDirection, then we will call this hook immediately.
 	OnCommitOnce(LinkDirection, func())
+
+	// InitStfu allows us to initiate quiescence on this link. It returns
+	// a receive only channel that will block until quiescence has been
+	// achieved, or definitively fails. The return value is the
+	// ChannelParty who holds the role of initiator or Err if the operation
+	// fails.
+	//
+	// This operation has been added to allow channels to be quiesced via
+	// RPC. It may be removed or reworked in the future as RPC initiated
+	// quiescence is a holdover until we have downstream protocols that use
+	// it.
+	InitStfu() <-chan fn.Result[lntypes.ChannelParty]
 }
 
 // CommitHookID is a value that is used to uniquely identify hooks in the

htlcswitch/link.go

@@ -283,6 +283,10 @@ type ChannelLinkConfig struct {
 	// invalid.
 	DisallowRouteBlinding bool
 
+	// DisallowQuiescence is a flag that can be used to disable the
+	// quiescence protocol.
+	DisallowQuiescence bool
+
 	// MaxFeeExposure is the threshold in milli-satoshis after which we'll
 	// restrict the flow of HTLCs and fee updates.
 	MaxFeeExposure lnwire.MilliSatoshi
@@ -392,6 +396,15 @@ type channelLink struct {
 	// our next CommitSig.
 	incomingCommitHooks hookMap
 
+	// quiescer is the state machine that tracks where this channel is with
+	// respect to the quiescence protocol.
+	quiescer Quiescer
+
+	// quiescenceReqs is a queue of requests to quiesce this link. The
+	// members of the queue are send-only channels we should call back with
+	// the result.
+	quiescenceReqs chan StfuReq
+
 	// ContextGuard is a helper that encapsulates a wait group and quit
 	// channel and allows contexts that either block or cancel on those
 	// depending on the use case.
@@ -467,6 +480,29 @@ func NewChannelLink(cfg ChannelLinkConfig,
 		cfg.MaxFeeExposure = DefaultMaxFeeExposure
 	}
 
+	var qsm Quiescer
+	if !cfg.DisallowQuiescence {
+		qsm = NewQuiescer(QuiescerCfg{
+			chanID: lnwire.NewChanIDFromOutPoint(
+				channel.ChannelPoint(),
+			),
+			channelInitiator: channel.Initiator(),
+			sendMsg: func(s lnwire.Stfu) error {
+				return cfg.Peer.SendMessage(false, &s)
+			},
+			timeoutDuration: defaultQuiescenceTimeout,
+			onTimeout: func() {
+				cfg.Peer.Disconnect(ErrQuiescenceTimeout)
+			},
+		})
+	} else {
+		qsm = &quiescerNoop{}
+	}
+
+	quiescenceReqs := make(
+		chan fn.Req[fn.Unit, fn.Result[lntypes.ChannelParty]], 1,
+	)
+
 	return &channelLink{
 		cfg:                 cfg,
 		channel:             channel,
@@ -476,6 +512,8 @@ func NewChannelLink(cfg ChannelLinkConfig,
 		flushHooks:          newHookMap(),
 		outgoingCommitHooks: newHookMap(),
 		incomingCommitHooks: newHookMap(),
+		quiescer:            qsm,
+		quiescenceReqs:      quiescenceReqs,
 		ContextGuard:        fn.NewContextGuard(),
 	}
 }
@@ -628,20 +666,37 @@ func (l *channelLink) WaitForShutdown() {
 // actively accept requests to forward HTLC's. We're able to forward HTLC's if
 // we are eligible to update AND the channel isn't currently flushing the
 // outgoing half of the channel.
+//
+// NOTE: MUST NOT be called from the main event loop.
 func (l *channelLink) EligibleToForward() bool {
-	return l.EligibleToUpdate() &&
-		!l.IsFlushing(Outgoing)
+	l.RLock()
+	defer l.RUnlock()
+
+	return l.eligibleToForward()
 }
 
-// EligibleToUpdate returns a bool indicating if the channel is able to update
+// eligibleToForward returns a bool indicating if the channel is able to
+// actively accept requests to forward HTLC's. We're able to forward HTLC's if
+// we are eligible to update AND the channel isn't currently flushing the
+// outgoing half of the channel.
+//
+// NOTE: MUST be called from the main event loop.
+func (l *channelLink) eligibleToForward() bool {
+	return l.eligibleToUpdate() && !l.IsFlushing(Outgoing)
+}
+
+// eligibleToUpdate returns a bool indicating if the channel is able to update
 // channel state. We're able to update channel state if we know the remote
 // party's next revocation point. Otherwise, we can't initiate new channel
 // state. We also require that the short channel ID not be the all-zero source
 // ID, meaning that the channel has had its ID finalized.
-func (l *channelLink) EligibleToUpdate() bool {
+//
+// NOTE: MUST be called from the main event loop.
+func (l *channelLink) eligibleToUpdate() bool {
 	return l.channel.RemoteNextRevocation() != nil &&
-		l.ShortChanID() != hop.Source &&
-		l.isReestablished()
+		l.channel.ShortChanID() != hop.Source &&
+		l.isReestablished() &&
+		l.quiescer.CanSendUpdates()
 }
 
 // EnableAdds sets the ChannelUpdateHandler state to allow UpdateAddHtlc's in
@@ -705,6 +760,27 @@ func (l *channelLink) OnCommitOnce(direction LinkDirection, hook func()) {
 	}
 }
 
+// InitStfu allows us to initiate quiescence on this link. It returns a receive
+// only channel that will block until quiescence has been achieved, or
+// definitively fails.
+//
+// This operation has been added to allow channels to be quiesced via RPC. It
+// may be removed or reworked in the future as RPC initiated quiescence is a
+// holdover until we have downstream protocols that use it.
+func (l *channelLink) InitStfu() <-chan fn.Result[lntypes.ChannelParty] {
+	req, out := fn.NewReq[fn.Unit, fn.Result[lntypes.ChannelParty]](
+		fn.Unit{},
+	)
+
+	select {
+	case l.quiescenceReqs <- req:
+	case <-l.Quit:
+		req.Resolve(fn.Err[lntypes.ChannelParty](ErrLinkShuttingDown))
+	}
+
+	return out
+}
+
 // isReestablished returns true if the link has successfully completed the
 // channel reestablishment dance.
 func (l *channelLink) isReestablished() bool {
@@ -1450,6 +1526,20 @@ func (l *channelLink) htlcManager() {
 				)
 			}
 
+		case qReq := <-l.quiescenceReqs:
+			l.quiescer.InitStfu(qReq)
+
+			if l.noDanglingUpdates(lntypes.Local) {
+				err := l.quiescer.SendOwedStfu()
+				if err != nil {
+					l.stfuFailf(
+						"SendOwedStfu: %s", err.Error(),
+					)
+					res := fn.Err[lntypes.ChannelParty](err)
+					qReq.Resolve(res)
+				}
+			}
+
 		case <-l.Quit:
 			return
 		}
@@ -1584,13 +1674,14 @@ func (l *channelLink) handleDownstreamUpdateAdd(pkt *htlcPacket) error {
 		return errors.New("not an UpdateAddHTLC packet")
 	}
 
-	// If we are flushing the link in the outgoing direction we can't add
-	// new htlcs to the link and we need to bounce it
-	if l.IsFlushing(Outgoing) {
+	// If we are flushing the link in the outgoing direction or we have
+	// already sent Stfu, then we can't add new htlcs to the link and we
+	// need to bounce it.
+	if l.IsFlushing(Outgoing) || !l.quiescer.CanSendUpdates() {
 		l.mailBox.FailAdd(pkt)
 
 		return NewDetailedLinkError(
-			&lnwire.FailPermanentChannelFailure{},
+			&lnwire.FailTemporaryChannelFailure{},
 			OutgoingFailureLinkNotEligible,
 		)
 	}
@@ -1693,6 +1784,15 @@ func (l *channelLink) handleDownstreamUpdateAdd(pkt *htlcPacket) error {
 //
 // TODO(roasbeef): add sync ntfn to ensure switch always has consistent view?
 func (l *channelLink) handleDownstreamPkt(pkt *htlcPacket) {
+	if pkt.htlc.MsgType().IsChannelUpdate() &&
+		!l.quiescer.CanSendUpdates() {
+
+		l.log.Warnf("unable to process channel update. "+
+			"ChannelID=%v is quiescent.", l.ChanID)
+
+		return
+	}
+
 	switch htlc := pkt.htlc.(type) {
 	case *lnwire.UpdateAddHTLC:
 		// Handle add message. The returned error can be ignored,
@@ -1937,6 +2037,13 @@ func (l *channelLink) cleanupSpuriousResponse(pkt *htlcPacket) {
 // updates from the upstream peer. The upstream peer is the peer whom we have a
 // direct channel with, updating our respective commitment chains.
 func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
+	// First check if the message is an update and we are capable of
+	// receiving updates right now.
+	if msg.MsgType().IsChannelUpdate() && !l.quiescer.CanRecvUpdates() {
+		l.stfuFailf("update received after stfu: %T", msg)
+		return
+	}
+
 	switch msg := msg.(type) {
 	case *lnwire.UpdateAddHTLC:
 		if l.IsFlushing(Incoming) {
@@ -2325,6 +2432,15 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 			}
 		}
 
+		// If we need to send out an Stfu, this would be the time to do
+		// so.
+		if l.noDanglingUpdates(lntypes.Local) {
+			err = l.quiescer.SendOwedStfu()
+			if err != nil {
+				l.stfuFailf("sendOwedStfu: %v", err.Error())
+			}
+		}
+
 		// Now that we have finished processing the incoming CommitSig
 		// and sent out our RevokeAndAck, we invoke the flushHooks if
 		// the channel state is clean.
@@ -2391,8 +2507,22 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 			}
 		}
 
+		// If we can send updates then we can process adds in case we
+		// are the exit hop and need to send back resolutions, or in
+		// case there are validity issues with the packets. Otherwise
+		// we defer the action until resume.
+		//
+		// We are free to process the settles and fails without this
+		// check since processing those can't result in further updates
+		// to this channel link.
+		if l.quiescer.CanSendUpdates() {
+			l.processRemoteAdds(fwdPkg)
+		} else {
+			l.quiescer.OnResume(func() {
+				l.processRemoteAdds(fwdPkg)
+			})
+		}
 		l.processRemoteSettleFails(fwdPkg)
-		l.processRemoteAdds(fwdPkg)
 
 		// If the link failed during processing the adds, we must
 		// return to ensure we won't attempted to update the state
@@ -2458,6 +2588,12 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 		// Update the mailbox's feerate as well.
 		l.mailBox.SetFeeRate(fee)
 
+	case *lnwire.Stfu:
+		err := l.handleStfu(msg)
+		if err != nil {
+			l.stfuFailf("handleStfu: %v", err.Error())
+		}
+
 	// In the case where we receive a warning message from our peer, just
 	// log it and move on. We choose not to disconnect from our peer,
 	// although we "MAY" do so according to the specification.
@@ -2490,6 +2626,50 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 
 }
 
+// handleStfu implements the top-level logic for handling the Stfu message from
+// our peer.
+func (l *channelLink) handleStfu(stfu *lnwire.Stfu) error {
+	if !l.noDanglingUpdates(lntypes.Remote) {
+		return ErrPendingRemoteUpdates
+	}
+	err := l.quiescer.RecvStfu(*stfu)
+	if err != nil {
+		return err
+	}
+
+	// If we can immediately send an Stfu response back, we will.
+	if l.noDanglingUpdates(lntypes.Local) {
+		return l.quiescer.SendOwedStfu()
+	}
+
+	return nil
+}
+
+// stfuFailf fails the link in the case where the requirements of the quiescence
+// protocol are violated. In all cases we opt to drop the connection as only
+// link state (as opposed to channel state) is affected.
+func (l *channelLink) stfuFailf(format string, args ...interface{}) {
+	l.failf(LinkFailureError{
+		code:             ErrStfuViolation,
+		FailureAction:    LinkFailureDisconnect,
+		PermanentFailure: false,
+		Warning:          true,
+	}, format, args...)
+}
+
+// noDanglingUpdates returns true when there are 0 updates that were originally
+// issued by whose on either the Local or Remote commitment transaction.
+func (l *channelLink) noDanglingUpdates(whose lntypes.ChannelParty) bool {
+	pendingOnLocal := l.channel.NumPendingUpdates(
+		whose, lntypes.Local,
+	)
+	pendingOnRemote := l.channel.NumPendingUpdates(
+		whose, lntypes.Remote,
+	)
+
+	return pendingOnLocal == 0 && pendingOnRemote == 0
+}
+
 // ackDownStreamPackets is responsible for removing htlcs from a link's mailbox
 // for packets delivered from server, and cleaning up any circuits closed by
 // signing a previous commitment txn. This method ensures that the circuits are
@@ -3293,7 +3473,7 @@ func (l *channelLink) updateChannelFee(feePerKw chainfee.SatPerKWeight) error {
 
 	// We skip sending the UpdateFee message if the channel is not
 	// currently eligible to forward messages.
-	if !l.EligibleToUpdate() {
+	if !l.eligibleToUpdate() {
 		l.log.Debugf("skipping fee update for inactive channel")
 		return nil
 	}

htlcswitch/link_test.go

@@ -7540,3 +7540,92 @@ func TestLinkFlushHooksCalled(t *testing.T) {
 	ctx.receiveRevAndAckAliceToBob()
 	assertHookCalled(true)
 }
+
+// TestLinkQuiescenceExitHopProcessingDeferred ensures that we do not send back
+// htlc resolution messages in the case where the link is quiescent AND we are
+// the exit hop. This is needed because we handle exit hop processing in the
+// link instead of the switch and we process htlc resolutions when we receive
+// a RevokeAndAck. Because of this we need to ensure that we hold off on
+// processing the remote adds when we are quiescent. Later, when the channel
+// update traffic is allowed to resume, we will need to verify that the actions
+// we didn't run during the initial RevokeAndAck are run.
+func TestLinkQuiescenceExitHopProcessingDeferred(t *testing.T) {
+	t.Parallel()
+
+	// Initialize two channel state machines for testing.
+	alice, bob, err := createMirroredChannel(
+		t, btcutil.SatoshiPerBitcoin, btcutil.SatoshiPerBitcoin,
+	)
+	require.NoError(t, err)
+
+	// Build a single edge network to test channel quiescence.
+	network := newTwoHopNetwork(
+		t, alice.channel, bob.channel, testStartingHeight,
+	)
+	aliceLink := network.aliceChannelLink
+	bobLink := network.bobChannelLink
+
+	// Generate an invoice for Bob so that Alice can pay him.
+	htlcID := uint64(0)
+	htlc, invoice := generateHtlcAndInvoice(t, htlcID)
+	err = network.bobServer.registry.AddInvoice(
+		nil, *invoice, htlc.PaymentHash,
+	)
+	require.NoError(t, err)
+
+	// Establish a payment circuit for Alice
+	circuit := &PaymentCircuit{
+		Incoming: CircuitKey{
+			HtlcID: htlcID,
+		},
+		PaymentHash: htlc.PaymentHash,
+	}
+	circuitMap := network.aliceServer.htlcSwitch.circuits
+	_, err = circuitMap.CommitCircuits(circuit)
+	require.NoError(t, err)
+
+	// Add a switch packet to Alice's switch so that she can initialize the
+	// payment attempt.
+	err = aliceLink.handleSwitchPacket(&htlcPacket{
+		incomingHTLCID: htlcID,
+		htlc:           htlc,
+		circuit:        circuit,
+	})
+	require.NoError(t, err)
+
+	// give alice enough time to fire the update_add
+	// TODO(proofofkeags): make this not depend on a flakey sleep.
+	<-time.After(time.Millisecond)
+
+	// bob initiates stfu which he can do immediately since he doesn't have
+	// local updates
+	<-bobLink.InitStfu()
+
+	// wait for other possible messages to play out
+	<-time.After(1 * time.Second)
+
+	ensureNoUpdateAfterStfu := func(t *testing.T, trace []lnwire.Message) {
+		stfuReceived := false
+		for _, msg := range trace {
+			if msg.MsgType() == lnwire.MsgStfu {
+				stfuReceived = true
+				continue
+			}
+
+			if stfuReceived && msg.MsgType().IsChannelUpdate() {
+				t.Fatalf("channel update after stfu: %v",
+					msg.MsgType())
+			}
+		}
+	}
+
+	network.aliceServer.protocolTraceMtx.Lock()
+	ensureNoUpdateAfterStfu(t, network.aliceServer.protocolTrace)
+	network.aliceServer.protocolTraceMtx.Unlock()
+
+	network.bobServer.protocolTraceMtx.Lock()
+	ensureNoUpdateAfterStfu(t, network.bobServer.protocolTrace)
+	network.bobServer.protocolTraceMtx.Unlock()
+
+	// TODO(proofofkeags): make sure these actions are run on resume.
+}

htlcswitch/linkfailure.go

@@ -51,6 +51,12 @@ const (
 	// circuit map. This is non-fatal and will resolve itself (usually
 	// within several minutes).
 	ErrCircuitError
+
+	// ErrStfuViolation indicates that the quiescence protocol has been
+	// violated, either because Stfu has been sent/received at an invalid
+	// time, or that an update has been sent/received while the channel is
+	// quiesced.
+	ErrStfuViolation
 )
 
 // LinkFailureAction is an enum-like type that describes the action that should
@@ -122,6 +128,8 @@ func (e LinkFailureError) Error() string {
 		return "unable to resume channel, recovery required"
 	case ErrCircuitError:
 		return "non-fatal circuit map error"
+	case ErrStfuViolation:
+		return "quiescence protocol executed improperly"
 	default:
 		return "unknown error"
 	}

htlcswitch/mock.go

@@ -153,8 +153,10 @@ type mockServer struct {
 
 	t testing.TB
 
-	name     string
-	messages chan lnwire.Message
+	name             string
+	messages         chan lnwire.Message
+	protocolTraceMtx sync.Mutex
+	protocolTrace    []lnwire.Message
 
 	id         [33]byte
 	htlcSwitch *Switch
@@ -289,6 +291,10 @@ func (s *mockServer) Start() error {
 		for {
 			select {
 			case msg := <-s.messages:
+				s.protocolTraceMtx.Lock()
+				s.protocolTrace = append(s.protocolTrace, msg)
+				s.protocolTraceMtx.Unlock()
+
 				var shouldSkip bool
 
 				for _, interceptor := range s.interceptorFuncs {
@@ -627,6 +633,8 @@ func (s *mockServer) readHandler(message lnwire.Message) error {
 		targetChan = msg.ChanID
 	case *lnwire.UpdateFee:
 		targetChan = msg.ChanID
+	case *lnwire.Stfu:
+		targetChan = msg.ChanID
 	default:
 		return fmt.Errorf("unknown message type: %T", msg)
 	}
@@ -950,6 +958,14 @@ func (f *mockChannelLink) OnFlushedOnce(func()) {
 func (f *mockChannelLink) OnCommitOnce(LinkDirection, func()) {
 	// TODO(proofofkeags): Implement
 }
+func (f *mockChannelLink) InitStfu() <-chan fn.Result[lntypes.ChannelParty] {
+	// TODO(proofofkeags): Implement
+	c := make(chan fn.Result[lntypes.ChannelParty], 1)
+
+	c <- fn.Errf[lntypes.ChannelParty]("InitStfu not implemented")
+
+	return c
+}
 
 func (f *mockChannelLink) FundingCustomBlob() fn.Option[tlv.Blob] {
 	return fn.None[tlv.Blob]()

htlcswitch/quiescer.go

@@ -0,0 +1,575 @@
+package htlcswitch
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/btcsuite/btclog/v2"
+	"github.com/lightningnetwork/lnd/build"
+	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/lnwire"
+)
+
+var (
+	// ErrInvalidStfu indicates that the Stfu we have received is invalid.
+	// This can happen in instances where we have not sent Stfu but we have
+	// received one with the initiator field set to false.
+	ErrInvalidStfu = fmt.Errorf("stfu received is invalid")
+
+	// ErrStfuAlreadySent indicates that this channel has already sent an
+	// Stfu message for this negotiation.
+	ErrStfuAlreadySent = fmt.Errorf("stfu already sent")
+
+	// ErrStfuAlreadyRcvd indicates that this channel has already received
+	// an Stfu message for this negotiation.
+	ErrStfuAlreadyRcvd = fmt.Errorf("stfu already received")
+
+	// ErrNoQuiescenceInitiator indicates that the caller has requested the
+	// quiescence initiator for a channel that is not yet quiescent.
+	ErrNoQuiescenceInitiator = fmt.Errorf(
+		"indeterminate quiescence initiator: channel is not quiescent",
+	)
+
+	// ErrPendingRemoteUpdates indicates that we have received an Stfu while
+	// the remote party has issued updates that are not yet bilaterally
+	// committed.
+	ErrPendingRemoteUpdates = fmt.Errorf(
+		"stfu received with pending remote updates",
+	)
+
+	// ErrPendingLocalUpdates indicates that we are attempting to send an
+	// Stfu while we have issued updates that are not yet bilaterally
+	// committed.
+	ErrPendingLocalUpdates = fmt.Errorf(
+		"stfu send attempted with pending local updates",
+	)
+
+	// ErrQuiescenceTimeout indicates that the quiescer has been quiesced
+	// beyond the allotted time.
+	ErrQuiescenceTimeout = fmt.Errorf(
+		"quiescence timeout",
+	)
+)
+
+const defaultQuiescenceTimeout = 30 * time.Second
+
+type StfuReq = fn.Req[fn.Unit, fn.Result[lntypes.ChannelParty]]
+
+// Quiescer is the public interface of the quiescence mechanism. Callers of the
+// quiescence API should not need any methods besides the ones detailed here.
+type Quiescer interface {
+	// IsQuiescent returns true if the state machine has been driven all the
+	// way to completion. If this returns true, processes that depend on
+	// channel quiescence may proceed.
+	IsQuiescent() bool
+
+	// QuiescenceInitiator determines which ChannelParty is the initiator of
+	// quiescence for the purposes of downstream protocols. If the channel
+	// is not currently quiescent, this method will return
+	// ErrNoDownstreamLeader.
+	QuiescenceInitiator() fn.Result[lntypes.ChannelParty]
+
+	// InitStfu instructs the quiescer that we intend to begin a quiescence
+	// negotiation where we are the initiator. We don't yet send stfu yet
+	// because we need to wait for the link to give us a valid opportunity
+	// to do so.
+	InitStfu(req StfuReq)
+
+	// RecvStfu is called when we receive an Stfu message from the remote.
+	RecvStfu(stfu lnwire.Stfu) error
+
+	// CanRecvUpdates returns true if we haven't yet received an Stfu which
+	// would mark the end of the remote's ability to send updates.
+	CanRecvUpdates() bool
+
+	// CanSendUpdates returns true if we haven't yet sent an Stfu which
+	// would mark the end of our ability to send updates.
+	CanSendUpdates() bool
+
+	// SendOwedStfu sends Stfu if it owes one. It returns an error if the
+	// state machine is in an invalid state.
+	SendOwedStfu() error
+
+	// OnResume accepts a no return closure that will run when the quiescer
+	// is resumed.
+	OnResume(hook func())
+
+	// Resume runs all of the deferred actions that have accumulated while
+	// the channel has been quiescent and then resets the quiescer state to
+	// its initial state.
+	Resume()
+}
+
+// QuiescerCfg is a config structure used to initialize a quiescer giving it the
+// appropriate functionality to interact with the channel state that the
+// quiescer must syncrhonize with.
+type QuiescerCfg struct {
+	// chanID marks what channel we are managing the state machine for. This
+	// is important because the quiescer needs to know the ChannelID to
+	// construct the Stfu message.
+	chanID lnwire.ChannelID
+
+	// channelInitiator indicates which ChannelParty originally opened the
+	// channel. This is used to break ties when both sides of the channel
+	// send Stfu claiming to be the initiator.
+	channelInitiator lntypes.ChannelParty
+
+	// sendMsg is a function that can be used to send an Stfu message over
+	// the wire.
+	sendMsg func(lnwire.Stfu) error
+
+	// timeoutDuration is the Duration that we will wait from the moment the
+	// channel is considered quiescent before we call the onTimeout function
+	timeoutDuration time.Duration
+
+	// onTimeout is a function that will be called in the event that the
+	// Quiescer has not been resumed before the timeout is reached. If
+	// Quiescer.Resume is called before the timeout has been raeached, then
+	// onTimeout will not be called until the quiescer reaches a quiescent
+	// state again.
+	onTimeout func()
+}
+
+// QuiescerLive is a state machine that tracks progression through the
+// quiescence protocol.
+type QuiescerLive struct {
+	cfg QuiescerCfg
+
+	// log is a quiescer-scoped logging instance.
+	log btclog.Logger
+
+	// localInit indicates whether our path through this state machine was
+	// initiated by our node. This can be true or false independently of
+	// remoteInit.
+	localInit bool
+
+	// remoteInit indicates whether we received Stfu from our peer where the
+	// message indicated that the remote node believes it was the initiator.
+	// This can be true or false independently of localInit.
+	remoteInit bool
+
+	// sent tracks whether or not we have emitted Stfu for sending.
+	sent bool
+
+	// received tracks whether or not we have received Stfu from our peer.
+	received bool
+
+	// activeQuiescenceRequest is a possibly None Request that we should
+	// resolve when we complete quiescence.
+	activeQuiescenceReq fn.Option[StfuReq]
+
+	// resumeQueue is a slice of hooks that will be called when the quiescer
+	// is resumed. These are actions that needed to be deferred while the
+	// channel was quiescent.
+	resumeQueue []func()
+
+	// timeoutTimer is a field that is used to hold onto the timeout job
+	// when we reach quiescence.
+	timeoutTimer *time.Timer
+
+	sync.RWMutex
+}
+
+// NewQuiescer creates a new quiescer for the given channel.
+func NewQuiescer(cfg QuiescerCfg) Quiescer {
+	logPrefix := fmt.Sprintf("Quiescer(%v):", cfg.chanID)
+
+	return &QuiescerLive{
+		cfg: cfg,
+		log: build.NewPrefixLog(logPrefix, log),
+	}
+}
+
+// RecvStfu is called when we receive an Stfu message from the remote.
+func (q *QuiescerLive) RecvStfu(msg lnwire.Stfu) error {
+	q.Lock()
+	defer q.Unlock()
+
+	return q.recvStfu(msg)
+}
+
+// recvStfu is called when we receive an Stfu message from the remote.
+func (q *QuiescerLive) recvStfu(msg lnwire.Stfu) error {
+	// At the time of this writing, this check that we have already received
+	// an Stfu is not strictly necessary, according to the specification.
+	// However, it is fishy if we do and it is unclear how we should handle
+	// such a case so we will err on the side of caution.
+	if q.received {
+		return fmt.Errorf("%w for channel %v", ErrStfuAlreadyRcvd,
+			q.cfg.chanID)
+	}
+
+	// We need to check that the Stfu we are receiving is valid.
+	if !q.sent && !msg.Initiator {
+		return fmt.Errorf("%w for channel %v", ErrInvalidStfu,
+			q.cfg.chanID)
+	}
+
+	if !q.canRecvStfu() {
+		return fmt.Errorf("%w for channel %v", ErrPendingRemoteUpdates,
+			q.cfg.chanID)
+	}
+
+	q.received = true
+
+	// If the remote party sets the initiator bit to true then we will
+	// remember that they are making a claim to the initiator role. This
+	// does not necessarily mean they will get it, though.
+	q.remoteInit = msg.Initiator
+
+	// Since we just received an Stfu, we may have a newly quiesced state.
+	// If so, we will try to resolve any outstanding StfuReqs.
+	q.tryResolveStfuReq()
+
+	if q.isQuiescent() {
+		q.startTimeout()
+	}
+
+	return nil
+}
+
+// MakeStfu is called when we are ready to send an Stfu message. It returns the
+// Stfu message to be sent.
+func (q *QuiescerLive) MakeStfu() fn.Result[lnwire.Stfu] {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.makeStfu()
+}
+
+// makeStfu is called when we are ready to send an Stfu message. It returns the
+// Stfu message to be sent.
+func (q *QuiescerLive) makeStfu() fn.Result[lnwire.Stfu] {
+	if q.sent {
+		return fn.Errf[lnwire.Stfu]("%w for channel %v",
+			ErrStfuAlreadySent, q.cfg.chanID)
+	}
+
+	if !q.canSendStfu() {
+		return fn.Errf[lnwire.Stfu]("%w for channel %v",
+			ErrPendingLocalUpdates, q.cfg.chanID)
+	}
+
+	stfu := lnwire.Stfu{
+		ChanID:    q.cfg.chanID,
+		Initiator: q.localInit,
+	}
+
+	return fn.Ok(stfu)
+}
+
+// OweStfu returns true if we owe the other party an Stfu. We owe the remote an
+// Stfu when we have received but not yet sent an Stfu, or we are the initiator
+// but have not yet sent an Stfu.
+func (q *QuiescerLive) OweStfu() bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.oweStfu()
+}
+
+// oweStfu returns true if we owe the other party an Stfu. We owe the remote an
+// Stfu when we have received but not yet sent an Stfu, or we are the initiator
+// but have not yet sent an Stfu.
+func (q *QuiescerLive) oweStfu() bool {
+	return (q.received || q.localInit) && !q.sent
+}
+
+// NeedStfu returns true if the remote owes us an Stfu. They owe us an Stfu when
+// we have sent but not yet received an Stfu.
+func (q *QuiescerLive) NeedStfu() bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.needStfu()
+}
+
+// needStfu returns true if the remote owes us an Stfu. They owe us an Stfu when
+// we have sent but not yet received an Stfu.
+func (q *QuiescerLive) needStfu() bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.sent && !q.received
+}
+
+// IsQuiescent returns true if the state machine has been driven all the way to
+// completion. If this returns true, processes that depend on channel quiescence
+// may proceed.
+func (q *QuiescerLive) IsQuiescent() bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.isQuiescent()
+}
+
+// isQuiescent returns true if the state machine has been driven all the way to
+// completion. If this returns true, processes that depend on channel quiescence
+// may proceed.
+func (q *QuiescerLive) isQuiescent() bool {
+	return q.sent && q.received
+}
+
+// QuiescenceInitiator determines which ChannelParty is the initiator of
+// quiescence for the purposes of downstream protocols. If the channel is not
+// currently quiescent, this method will return ErrNoQuiescenceInitiator.
+func (q *QuiescerLive) QuiescenceInitiator() fn.Result[lntypes.ChannelParty] {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.quiescenceInitiator()
+}
+
+// quiescenceInitiator determines which ChannelParty is the initiator of
+// quiescence for the purposes of downstream protocols. If the channel is not
+// currently quiescent, this method will return ErrNoQuiescenceInitiator.
+func (q *QuiescerLive) quiescenceInitiator() fn.Result[lntypes.ChannelParty] {
+	switch {
+	case !q.isQuiescent():
+		return fn.Err[lntypes.ChannelParty](ErrNoQuiescenceInitiator)
+
+	case q.localInit && q.remoteInit:
+		// In the case of a tie, the channel initiator wins.
+		return fn.Ok(q.cfg.channelInitiator)
+
+	case q.localInit:
+		return fn.Ok(lntypes.Local)
+
+	case q.remoteInit:
+		return fn.Ok(lntypes.Remote)
+	}
+
+	// unreachable
+	return fn.Err[lntypes.ChannelParty](ErrNoQuiescenceInitiator)
+}
+
+// CanSendUpdates returns true if we haven't yet sent an Stfu which would mark
+// the end of our ability to send updates.
+func (q *QuiescerLive) CanSendUpdates() bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.canSendUpdates()
+}
+
+// canSendUpdates returns true if we haven't yet sent an Stfu which would mark
+// the end of our ability to send updates.
+func (q *QuiescerLive) canSendUpdates() bool {
+	return !q.sent && !q.localInit
+}
+
+// CanRecvUpdates returns true if we haven't yet received an Stfu which would
+// mark the end of the remote's ability to send updates.
+func (q *QuiescerLive) CanRecvUpdates() bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.canRecvUpdates()
+}
+
+// canRecvUpdates returns true if we haven't yet received an Stfu which would
+// mark the end of the remote's ability to send updates.
+func (q *QuiescerLive) canRecvUpdates() bool {
+	return !q.received
+}
+
+// CanSendStfu returns true if we can send an Stfu.
+func (q *QuiescerLive) CanSendStfu(numPendingLocalUpdates uint64) bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.canSendStfu()
+}
+
+// canSendStfu returns true if we can send an Stfu.
+func (q *QuiescerLive) canSendStfu() bool {
+	return !q.sent
+}
+
+// CanRecvStfu returns true if we can receive an Stfu.
+func (q *QuiescerLive) CanRecvStfu() bool {
+	q.RLock()
+	defer q.RUnlock()
+
+	return q.canRecvStfu()
+}
+
+// canRecvStfu returns true if we can receive an Stfu.
+func (q *QuiescerLive) canRecvStfu() bool {
+	return !q.received
+}
+
+// SendOwedStfu sends Stfu if it owes one. It returns an error if the state
+// machine is in an invalid state.
+func (q *QuiescerLive) SendOwedStfu() error {
+	q.Lock()
+	defer q.Unlock()
+
+	return q.sendOwedStfu()
+}
+
+// sendOwedStfu sends Stfu if it owes one. It returns an error if the state
+// machine is in an invalid state.
+func (q *QuiescerLive) sendOwedStfu() error {
+	if !q.oweStfu() || !q.canSendStfu() {
+		return nil
+	}
+
+	err := q.makeStfu().Sink(q.cfg.sendMsg)
+
+	if err == nil {
+		q.sent = true
+
+		// Since we just sent an Stfu, we may have a newly quiesced
+		// state. If so, we will try to resolve any outstanding
+		// StfuReqs.
+		q.tryResolveStfuReq()
+
+		if q.isQuiescent() {
+			q.startTimeout()
+		}
+	}
+
+	return err
+}
+
+// TryResolveStfuReq attempts to resolve the active quiescence request if the
+// state machine has reached a quiescent state.
+func (q *QuiescerLive) TryResolveStfuReq() {
+	q.Lock()
+	defer q.Unlock()
+
+	q.tryResolveStfuReq()
+}
+
+// tryResolveStfuReq attempts to resolve the active quiescence request if the
+// state machine has reached a quiescent state.
+func (q *QuiescerLive) tryResolveStfuReq() {
+	q.activeQuiescenceReq.WhenSome(
+		func(req StfuReq) {
+			if q.isQuiescent() {
+				req.Resolve(q.quiescenceInitiator())
+				q.activeQuiescenceReq = fn.None[StfuReq]()
+			}
+		},
+	)
+}
+
+// InitStfu instructs the quiescer that we intend to begin a quiescence
+// negotiation where we are the initiator. We don't yet send stfu yet because
+// we need to wait for the link to give us a valid opportunity to do so.
+func (q *QuiescerLive) InitStfu(req StfuReq) {
+	q.Lock()
+	defer q.Unlock()
+
+	q.initStfu(req)
+}
+
+// initStfu instructs the quiescer that we intend to begin a quiescence
+// negotiation where we are the initiator. We don't yet send stfu yet because
+// we need to wait for the link to give us a valid opportunity to do so.
+func (q *QuiescerLive) initStfu(req StfuReq) {
+	if q.localInit {
+		req.Resolve(fn.Errf[lntypes.ChannelParty](
+			"quiescence already requested",
+		))
+
+		return
+	}
+
+	q.localInit = true
+	q.activeQuiescenceReq = fn.Some(req)
+}
+
+// OnResume accepts a no return closure that will run when the quiescer is
+// resumed.
+func (q *QuiescerLive) OnResume(hook func()) {
+	q.Lock()
+	defer q.Unlock()
+
+	q.onResume(hook)
+}
+
+// onResume accepts a no return closure that will run when the quiescer is
+// resumed.
+func (q *QuiescerLive) onResume(hook func()) {
+	q.resumeQueue = append(q.resumeQueue, hook)
+}
+
+// Resume runs all of the deferred actions that have accumulated while the
+// channel has been quiescent and then resets the quiescer state to its initial
+// state.
+func (q *QuiescerLive) Resume() {
+	q.Lock()
+	defer q.Unlock()
+
+	q.resume()
+}
+
+// resume runs all of the deferred actions that have accumulated while the
+// channel has been quiescent and then resets the quiescer state to its initial
+// state.
+func (q *QuiescerLive) resume() {
+	q.log.Debug("quiescence terminated, resuming htlc traffic")
+
+	// since we are resuming we want to cancel the quiescence timeout
+	// action.
+	q.cancelTimeout()
+
+	for _, hook := range q.resumeQueue {
+		hook()
+	}
+	q.localInit = false
+	q.remoteInit = false
+	q.sent = false
+	q.received = false
+	q.resumeQueue = nil
+}
+
+// startTimeout starts the timeout function that fires if the quiescer remains
+// in a quiesced state for too long. If this function is called multiple times
+// only the last one will have an effect.
+func (q *QuiescerLive) startTimeout() {
+	if q.cfg.onTimeout == nil {
+		return
+	}
+
+	old := q.timeoutTimer
+
+	q.timeoutTimer = time.AfterFunc(q.cfg.timeoutDuration, q.cfg.onTimeout)
+
+	if old != nil {
+		old.Stop()
+	}
+}
+
+// cancelTimeout cancels the timeout function that would otherwise fire if the
+// quiescer remains in a quiesced state too long. If this function is called
+// before startTimeout or after another call to cancelTimeout, the effect will
+// be a noop.
+func (q *QuiescerLive) cancelTimeout() {
+	if q.timeoutTimer != nil {
+		q.timeoutTimer.Stop()
+		q.timeoutTimer = nil
+	}
+}
+
+type quiescerNoop struct{}
+
+var _ Quiescer = (*quiescerNoop)(nil)
+
+func (q *quiescerNoop) InitStfu(req StfuReq) {
+	req.Resolve(fn.Errf[lntypes.ChannelParty]("quiescence not supported"))
+}
+func (q *quiescerNoop) RecvStfu(_ lnwire.Stfu) error { return nil }
+func (q *quiescerNoop) CanRecvUpdates() bool         { return true }
+func (q *quiescerNoop) CanSendUpdates() bool         { return true }
+func (q *quiescerNoop) SendOwedStfu() error          { return nil }
+func (q *quiescerNoop) IsQuiescent() bool            { return false }
+func (q *quiescerNoop) OnResume(hook func())         { hook() }
+func (q *quiescerNoop) Resume()                      {}
+func (q *quiescerNoop) QuiescenceInitiator() fn.Result[lntypes.ChannelParty] {
+	return fn.Err[lntypes.ChannelParty](ErrNoQuiescenceInitiator)
+}

htlcswitch/quiescer_test.go

@@ -0,0 +1,374 @@
+package htlcswitch
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/stretchr/testify/require"
+)
+
+var cid = lnwire.ChannelID(bytes.Repeat([]byte{0x00}, 32))
+
+type quiescerTestHarness struct {
+	quiescer *QuiescerLive
+	conn     <-chan lnwire.Stfu
+}
+
+func initQuiescerTestHarness(
+	channelInitiator lntypes.ChannelParty) *quiescerTestHarness {
+
+	conn := make(chan lnwire.Stfu, 1)
+	harness := &quiescerTestHarness{
+		conn: conn,
+	}
+
+	quiescer, _ := NewQuiescer(QuiescerCfg{
+		chanID:           cid,
+		channelInitiator: channelInitiator,
+		sendMsg: func(msg lnwire.Stfu) error {
+			conn <- msg
+			return nil
+		},
+	}).(*QuiescerLive)
+
+	harness.quiescer = quiescer
+
+	return harness
+}
+
+// TestQuiescerDoubleRecvInvalid ensures that we get an error response when we
+// receive the Stfu message twice during the lifecycle of the quiescer.
+func TestQuiescerDoubleRecvInvalid(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+
+	err := harness.quiescer.RecvStfu(msg)
+	require.NoError(t, err)
+	err = harness.quiescer.RecvStfu(msg)
+	require.Error(t, err, ErrStfuAlreadyRcvd)
+}
+
+// TestQuiescenceRemoteInit ensures that we can successfully traverse the state
+// graph of quiescence beginning with the Remote party initiating quiescence.
+func TestQuiescenceRemoteInit(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+
+	err := harness.quiescer.RecvStfu(msg)
+	require.NoError(t, err)
+
+	err = harness.quiescer.SendOwedStfu()
+	require.NoError(t, err)
+
+	select {
+	case msg := <-harness.conn:
+		require.False(t, msg.Initiator)
+	default:
+		t.Fatalf("stfu not sent when expected")
+	}
+}
+
+func TestQuiescenceLocalInit(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+
+	stfuReq, stfuRes := fn.NewReq[fn.Unit, fn.Result[lntypes.ChannelParty]](
+		fn.Unit{},
+	)
+	harness.quiescer.InitStfu(stfuReq)
+
+	err := harness.quiescer.SendOwedStfu()
+	require.NoError(t, err)
+
+	select {
+	case msg := <-harness.conn:
+		require.True(t, msg.Initiator)
+	default:
+		t.Fatalf("stfu not sent when expected")
+	}
+
+	err = harness.quiescer.RecvStfu(msg)
+	require.NoError(t, err)
+
+	select {
+	case party := <-stfuRes:
+		require.Equal(t, fn.Ok(lntypes.Local), party)
+	default:
+		t.Fatalf("quiescence request not resolved")
+	}
+}
+
+// TestQuiescenceInitiator ensures that the quiescenceInitiator is the Remote
+// party when we have a receive first traversal of the quiescer's state graph.
+func TestQuiescenceInitiator(t *testing.T) {
+	t.Parallel()
+
+	// Remote Initiated
+	harness := initQuiescerTestHarness(lntypes.Local)
+	require.True(t, harness.quiescer.QuiescenceInitiator().IsErr())
+
+	// Receive
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+	require.NoError(t, harness.quiescer.RecvStfu(msg))
+	require.True(t, harness.quiescer.QuiescenceInitiator().IsErr())
+
+	// Send
+	require.NoError(t, harness.quiescer.SendOwedStfu())
+	require.Equal(
+		t, harness.quiescer.QuiescenceInitiator(),
+		fn.Ok(lntypes.Remote),
+	)
+
+	// Local Initiated
+	harness = initQuiescerTestHarness(lntypes.Local)
+	require.True(t, harness.quiescer.quiescenceInitiator().IsErr())
+
+	req, res := fn.NewReq[fn.Unit, fn.Result[lntypes.ChannelParty]](
+		fn.Unit{},
+	)
+	harness.quiescer.initStfu(req)
+	req2, res2 := fn.NewReq[fn.Unit, fn.Result[lntypes.ChannelParty]](
+		fn.Unit{},
+	)
+	harness.quiescer.initStfu(req2)
+	select {
+	case initiator := <-res2:
+		require.True(t, initiator.IsErr())
+	default:
+		t.Fatal("quiescence request not resolved")
+	}
+
+	require.NoError(
+		t, harness.quiescer.sendOwedStfu(),
+	)
+	require.True(t, harness.quiescer.quiescenceInitiator().IsErr())
+
+	msg = lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: false,
+	}
+	require.NoError(t, harness.quiescer.recvStfu(msg))
+	require.True(t, harness.quiescer.quiescenceInitiator().IsOk())
+
+	select {
+	case initiator := <-res:
+		require.Equal(t, fn.Ok(lntypes.Local), initiator)
+	default:
+		t.Fatal("quiescence request not resolved")
+	}
+}
+
+// TestQuiescenceCantReceiveUpdatesAfterStfu tests that we can receive channel
+// updates prior to but not after we receive Stfu.
+func TestQuiescenceCantReceiveUpdatesAfterStfu(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+	require.True(t, harness.quiescer.CanRecvUpdates())
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+	require.NoError(t, harness.quiescer.RecvStfu(msg))
+	require.False(t, harness.quiescer.CanRecvUpdates())
+}
+
+// TestQuiescenceCantSendUpdatesAfterStfu tests that we can send channel updates
+// prior to but not after we send Stfu.
+func TestQuiescenceCantSendUpdatesAfterStfu(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+	require.True(t, harness.quiescer.CanSendUpdates())
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+
+	err := harness.quiescer.RecvStfu(msg)
+	require.NoError(t, err)
+
+	err = harness.quiescer.SendOwedStfu()
+	require.NoError(t, err)
+
+	require.False(t, harness.quiescer.CanSendUpdates())
+}
+
+// TestQuiescenceStfuNotNeededAfterRecv tests that after we receive an Stfu we
+// do not needStfu either before or after receiving it if we do not initiate
+// quiescence.
+func TestQuiescenceStfuNotNeededAfterRecv(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+	require.False(t, harness.quiescer.NeedStfu())
+
+	require.NoError(t, harness.quiescer.RecvStfu(msg))
+
+	require.False(t, harness.quiescer.NeedStfu())
+}
+
+// TestQuiescenceInappropriateMakeStfuReturnsErr ensures that we cannot call
+// makeStfu at times when it would be a protocol violation to send it.
+func TestQuiescenceInappropriateMakeStfuReturnsErr(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+	require.NoError(t, harness.quiescer.RecvStfu(msg))
+	require.True(t, harness.quiescer.MakeStfu().IsOk())
+
+	require.NoError(t, harness.quiescer.SendOwedStfu())
+	require.True(t, harness.quiescer.MakeStfu().IsErr())
+}
+
+// TestQuiescerTieBreaker ensures that if both parties attempt to claim the
+// initiator role that the result of the negotiation breaks the tie using the
+// channel initiator.
+func TestQuiescerTieBreaker(t *testing.T) {
+	t.Parallel()
+
+	for _, initiator := range []lntypes.ChannelParty{
+		lntypes.Local, lntypes.Remote,
+	} {
+		harness := initQuiescerTestHarness(initiator)
+
+		msg := lnwire.Stfu{
+			ChanID:    cid,
+			Initiator: true,
+		}
+
+		req, res := fn.NewReq[fn.Unit, fn.Result[lntypes.ChannelParty]](
+			fn.Unit{},
+		)
+
+		harness.quiescer.InitStfu(req)
+		require.NoError(t, harness.quiescer.RecvStfu(msg))
+		require.NoError(t, harness.quiescer.SendOwedStfu())
+
+		select {
+		case party := <-res:
+			require.Equal(t, fn.Ok(initiator), party)
+		default:
+			t.Fatal("quiescence party unavailable")
+		}
+	}
+}
+
+// TestQuiescerResume ensures that the hooks that are attached to the quiescer
+// are called when we call the resume method and no earlier.
+func TestQuiescerResume(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+
+	require.NoError(t, harness.quiescer.RecvStfu(msg))
+	require.NoError(t, harness.quiescer.SendOwedStfu())
+
+	require.True(t, harness.quiescer.IsQuiescent())
+	var resumeHooksCalled = false
+	harness.quiescer.OnResume(func() {
+		resumeHooksCalled = true
+	})
+	require.False(t, resumeHooksCalled)
+
+	harness.quiescer.Resume()
+	require.True(t, resumeHooksCalled)
+	require.False(t, harness.quiescer.IsQuiescent())
+}
+
+func TestQuiescerTimeoutTriggers(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+
+	timeoutGate := make(chan struct{})
+
+	harness.quiescer.cfg.timeoutDuration = time.Second
+	harness.quiescer.cfg.onTimeout = func() { close(timeoutGate) }
+
+	err := harness.quiescer.RecvStfu(msg)
+	require.NoError(t, err)
+	err = harness.quiescer.SendOwedStfu()
+	require.NoError(t, err)
+
+	select {
+	case <-timeoutGate:
+	case <-time.After(2 * harness.quiescer.cfg.timeoutDuration):
+		t.Fatal("quiescence timeout did not trigger")
+	}
+}
+
+func TestQuiescerTimeoutAborts(t *testing.T) {
+	t.Parallel()
+
+	harness := initQuiescerTestHarness(lntypes.Local)
+
+	msg := lnwire.Stfu{
+		ChanID:    cid,
+		Initiator: true,
+	}
+
+	timeoutGate := make(chan struct{})
+
+	harness.quiescer.cfg.timeoutDuration = time.Second
+	harness.quiescer.cfg.onTimeout = func() { close(timeoutGate) }
+
+	err := harness.quiescer.RecvStfu(msg)
+	require.NoError(t, err)
+	err = harness.quiescer.SendOwedStfu()
+	require.NoError(t, err)
+	harness.quiescer.Resume()
+
+	select {
+	case <-timeoutGate:
+		t.Fatal("quiescence timeout triggered despite being resumed")
+	case <-time.After(2 * harness.quiescer.cfg.timeoutDuration):
+	}
+}

itest/list_on_test.go

@@ -710,4 +710,8 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "experimental endorsement",
 		TestFunc: testExperimentalEndorsement,
 	},
+	{
+		Name:     "quiescence",
+		TestFunc: testQuiescence,
+	},
 }

itest/lnd_quiescence_test.go

@@ -0,0 +1,48 @@
+package itest
+
+import (
+	"github.com/btcsuite/btcd/btcutil"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/devrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
+	"github.com/lightningnetwork/lnd/lntest"
+	"github.com/stretchr/testify/require"
+)
+
+// testQuiescence tests whether we can come to agreement on quiescence of a
+// channel. We initiate quiescence via RPC and if it succeeds we verify that
+// the expected initiator is the resulting initiator.
+//
+// NOTE FOR REVIEW: this could be improved by blasting the channel with HTLC
+// traffic on both sides to increase the surface area of the change under test.
+func testQuiescence(ht *lntest.HarnessTest) {
+	alice, bob := ht.Alice, ht.Bob
+
+	chanPoint := ht.OpenChannel(bob, alice, lntest.OpenChannelParams{
+		Amt: btcutil.Amount(1000000),
+	})
+	defer ht.CloseChannel(bob, chanPoint)
+
+	res := alice.RPC.Quiesce(&devrpc.QuiescenceRequest{
+		ChanId: chanPoint,
+	})
+
+	require.True(ht, res.Initiator)
+
+	req := &routerrpc.SendPaymentRequest{
+		Dest:           ht.Alice.PubKey[:],
+		Amt:            100,
+		PaymentHash:    ht.Random32Bytes(),
+		FinalCltvDelta: finalCltvDelta,
+		TimeoutSeconds: 60,
+		FeeLimitMsat:   noFeeLimitMsat,
+	}
+
+	ht.SendPaymentAssertFail(
+		ht.Bob, req,
+		// This fails with insufficient balance because the bandwidth
+		// manager reports 0 bandwidth if a link is not eligible for
+		// forwarding, which is the case during quiescence.
+		lnrpc.PaymentFailureReason_FAILURE_REASON_INSUFFICIENT_BALANCE,
+	)
+}

lncfg/protocol.go

@@ -141,6 +141,11 @@ func (l *ProtocolOptions) NoExperimentalEndorsement() bool {
 	return l.NoExperimentalEndorsementOption
 }
 
+// NoQuiescence returns true if quiescence is disabled.
+func (l *ProtocolOptions) NoQuiescence() bool {
+	return true
+}
+
 // CustomMessageOverrides returns the set of protocol messages that we override
 // to allow custom handling.
 func (p ProtocolOptions) CustomMessageOverrides() []uint16 {

lncfg/protocol_integration.go

@@ -73,6 +73,9 @@ type ProtocolOptions struct {
 	// NoExperimentalEndorsementOption disables experimental endorsement.
 	NoExperimentalEndorsementOption bool `long:"no-experimental-endorsement" description:"do not forward experimental endorsement signals"`
 
+	// NoQuiescenceOption disables quiescence for all channels.
+	NoQuiescenceOption bool `long:"no-quiescence" description:"do not allow or advertise quiescence for any channel"`
+
 	// CustomMessage allows the custom message APIs to handle messages with
 	// the provided protocol numbers, which fall outside the custom message
 	// number range.
@@ -136,6 +139,11 @@ func (l *ProtocolOptions) NoExperimentalEndorsement() bool {
 	return l.NoExperimentalEndorsementOption
 }
 
+// NoQuiescence returns true if quiescence is disabled.
+func (l *ProtocolOptions) NoQuiescence() bool {
+	return l.NoQuiescenceOption
+}
+
 // CustomMessageOverrides returns the set of protocol messages that we override
 // to allow custom handling.
 func (l ProtocolOptions) CustomMessageOverrides() []uint16 {

lnrpc/devrpc/config_active.go

@@ -6,6 +6,7 @@ package devrpc
 import (
 	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/htlcswitch"
 )
 
 // Config is the primary configuration struct for the DEV RPC server. It
@@ -16,4 +17,5 @@ import (
 type Config struct {
 	ActiveNetParams *chaincfg.Params
 	GraphDB         *channeldb.ChannelGraph
+	Switch          *htlcswitch.Switch
 }

lnrpc/devrpc/dev.pb.go

@@ -59,6 +59,103 @@ func (*ImportGraphResponse) Descriptor() ([]byte, []int) {
 	return file_devrpc_dev_proto_rawDescGZIP(), []int{0}
 }
 
+type QuiescenceRequest struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// The channel point of the channel we wish to quiesce
+	ChanId *lnrpc.ChannelPoint `protobuf:"bytes,1,opt,name=chan_id,json=chanId,proto3" json:"chan_id,omitempty"`
+}
+
+func (x *QuiescenceRequest) Reset() {
+	*x = QuiescenceRequest{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_devrpc_dev_proto_msgTypes[1]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *QuiescenceRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*QuiescenceRequest) ProtoMessage() {}
+
+func (x *QuiescenceRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_devrpc_dev_proto_msgTypes[1]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use QuiescenceRequest.ProtoReflect.Descriptor instead.
+func (*QuiescenceRequest) Descriptor() ([]byte, []int) {
+	return file_devrpc_dev_proto_rawDescGZIP(), []int{1}
+}
+
+func (x *QuiescenceRequest) GetChanId() *lnrpc.ChannelPoint {
+	if x != nil {
+		return x.ChanId
+	}
+	return nil
+}
+
+type QuiescenceResponse struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// Indicates whether or not we hold the initiator role or not once the
+	// negotiation completes
+	Initiator bool `protobuf:"varint,1,opt,name=initiator,proto3" json:"initiator,omitempty"`
+}
+
+func (x *QuiescenceResponse) Reset() {
+	*x = QuiescenceResponse{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_devrpc_dev_proto_msgTypes[2]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *QuiescenceResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*QuiescenceResponse) ProtoMessage() {}
+
+func (x *QuiescenceResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_devrpc_dev_proto_msgTypes[2]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use QuiescenceResponse.ProtoReflect.Descriptor instead.
+func (*QuiescenceResponse) Descriptor() ([]byte, []int) {
+	return file_devrpc_dev_proto_rawDescGZIP(), []int{2}
+}
+
+func (x *QuiescenceResponse) GetInitiator() bool {
+	if x != nil {
+		return x.Initiator
+	}
+	return false
+}
+
 var File_devrpc_dev_proto protoreflect.FileDescriptor
 
 var file_devrpc_dev_proto_rawDesc = []byte{
@@ -66,15 +163,26 @@ var file_devrpc_dev_proto_rawDesc = []byte{
 	0x74, 0x6f, 0x12, 0x06, 0x64, 0x65, 0x76, 0x72, 0x70, 0x63, 0x1a, 0x0f, 0x6c, 0x69, 0x67, 0x68,
 	0x74, 0x6e, 0x69, 0x6e, 0x67, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0x15, 0x0a, 0x13, 0x49,
 	0x6d, 0x70, 0x6f, 0x72, 0x74, 0x47, 0x72, 0x61, 0x70, 0x68, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e,
-	0x73, 0x65, 0x32, 0x46, 0x0a, 0x03, 0x44, 0x65, 0x76, 0x12, 0x3f, 0x0a, 0x0b, 0x49, 0x6d, 0x70,
-	0x6f, 0x72, 0x74, 0x47, 0x72, 0x61, 0x70, 0x68, 0x12, 0x13, 0x2e, 0x6c, 0x6e, 0x72, 0x70, 0x63,
-	0x2e, 0x43, 0x68, 0x61, 0x6e, 0x6e, 0x65, 0x6c, 0x47, 0x72, 0x61, 0x70, 0x68, 0x1a, 0x1b, 0x2e,
-	0x64, 0x65, 0x76, 0x72, 0x70, 0x63, 0x2e, 0x49, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x47, 0x72, 0x61,
-	0x70, 0x68, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x42, 0x2e, 0x5a, 0x2c, 0x67, 0x69,
-	0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x6c, 0x69, 0x67, 0x68, 0x74, 0x6e, 0x69,
-	0x6e, 0x67, 0x6e, 0x65, 0x74, 0x77, 0x6f, 0x72, 0x6b, 0x2f, 0x6c, 0x6e, 0x64, 0x2f, 0x6c, 0x6e,
-	0x72, 0x70, 0x63, 0x2f, 0x64, 0x65, 0x76, 0x72, 0x70, 0x63, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74,
-	0x6f, 0x33,
+	0x73, 0x65, 0x22, 0x41, 0x0a, 0x11, 0x51, 0x75, 0x69, 0x65, 0x73, 0x63, 0x65, 0x6e, 0x63, 0x65,
+	0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x12, 0x2c, 0x0a, 0x07, 0x63, 0x68, 0x61, 0x6e, 0x5f,
+	0x69, 0x64, 0x18, 0x01, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x13, 0x2e, 0x6c, 0x6e, 0x72, 0x70, 0x63,
+	0x2e, 0x43, 0x68, 0x61, 0x6e, 0x6e, 0x65, 0x6c, 0x50, 0x6f, 0x69, 0x6e, 0x74, 0x52, 0x06, 0x63,
+	0x68, 0x61, 0x6e, 0x49, 0x64, 0x22, 0x32, 0x0a, 0x12, 0x51, 0x75, 0x69, 0x65, 0x73, 0x63, 0x65,
+	0x6e, 0x63, 0x65, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x12, 0x1c, 0x0a, 0x09, 0x69,
+	0x6e, 0x69, 0x74, 0x69, 0x61, 0x74, 0x6f, 0x72, 0x18, 0x01, 0x20, 0x01, 0x28, 0x08, 0x52, 0x09,
+	0x69, 0x6e, 0x69, 0x74, 0x69, 0x61, 0x74, 0x6f, 0x72, 0x32, 0x88, 0x01, 0x0a, 0x03, 0x44, 0x65,
+	0x76, 0x12, 0x3f, 0x0a, 0x0b, 0x49, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x47, 0x72, 0x61, 0x70, 0x68,
+	0x12, 0x13, 0x2e, 0x6c, 0x6e, 0x72, 0x70, 0x63, 0x2e, 0x43, 0x68, 0x61, 0x6e, 0x6e, 0x65, 0x6c,
+	0x47, 0x72, 0x61, 0x70, 0x68, 0x1a, 0x1b, 0x2e, 0x64, 0x65, 0x76, 0x72, 0x70, 0x63, 0x2e, 0x49,
+	0x6d, 0x70, 0x6f, 0x72, 0x74, 0x47, 0x72, 0x61, 0x70, 0x68, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e,
+	0x73, 0x65, 0x12, 0x40, 0x0a, 0x07, 0x51, 0x75, 0x69, 0x65, 0x73, 0x63, 0x65, 0x12, 0x19, 0x2e,
+	0x64, 0x65, 0x76, 0x72, 0x70, 0x63, 0x2e, 0x51, 0x75, 0x69, 0x65, 0x73, 0x63, 0x65, 0x6e, 0x63,
+	0x65, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x1a, 0x1a, 0x2e, 0x64, 0x65, 0x76, 0x72, 0x70,
+	0x63, 0x2e, 0x51, 0x75, 0x69, 0x65, 0x73, 0x63, 0x65, 0x6e, 0x63, 0x65, 0x52, 0x65, 0x73, 0x70,
+	0x6f, 0x6e, 0x73, 0x65, 0x42, 0x2e, 0x5a, 0x2c, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63,
+	0x6f, 0x6d, 0x2f, 0x6c, 0x69, 0x67, 0x68, 0x74, 0x6e, 0x69, 0x6e, 0x67, 0x6e, 0x65, 0x74, 0x77,
+	0x6f, 0x72, 0x6b, 0x2f, 0x6c, 0x6e, 0x64, 0x2f, 0x6c, 0x6e, 0x72, 0x70, 0x63, 0x2f, 0x64, 0x65,
+	0x76, 0x72, 0x70, 0x63, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -89,19 +197,25 @@ func file_devrpc_dev_proto_rawDescGZIP() []byte {
 	return file_devrpc_dev_proto_rawDescData
 }
 
-var file_devrpc_dev_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_devrpc_dev_proto_msgTypes = make([]protoimpl.MessageInfo, 3)
 var file_devrpc_dev_proto_goTypes = []interface{}{
 	(*ImportGraphResponse)(nil), // 0: devrpc.ImportGraphResponse
-	(*lnrpc.ChannelGraph)(nil),  // 1: lnrpc.ChannelGraph
+	(*QuiescenceRequest)(nil),   // 1: devrpc.QuiescenceRequest
+	(*QuiescenceResponse)(nil),  // 2: devrpc.QuiescenceResponse
+	(*lnrpc.ChannelPoint)(nil),  // 3: lnrpc.ChannelPoint
+	(*lnrpc.ChannelGraph)(nil),  // 4: lnrpc.ChannelGraph
 }
 var file_devrpc_dev_proto_depIdxs = []int32{
-	1, // 0: devrpc.Dev.ImportGraph:input_type -> lnrpc.ChannelGraph
-	0, // 1: devrpc.Dev.ImportGraph:output_type -> devrpc.ImportGraphResponse
-	1, // [1:2] is the sub-list for method output_type
-	0, // [0:1] is the sub-list for method input_type
-	0, // [0:0] is the sub-list for extension type_name
-	0, // [0:0] is the sub-list for extension extendee
-	0, // [0:0] is the sub-list for field type_name
+	3, // 0: devrpc.QuiescenceRequest.chan_id:type_name -> lnrpc.ChannelPoint
+	4, // 1: devrpc.Dev.ImportGraph:input_type -> lnrpc.ChannelGraph
+	1, // 2: devrpc.Dev.Quiesce:input_type -> devrpc.QuiescenceRequest
+	0, // 3: devrpc.Dev.ImportGraph:output_type -> devrpc.ImportGraphResponse
+	2, // 4: devrpc.Dev.Quiesce:output_type -> devrpc.QuiescenceResponse
+	3, // [3:5] is the sub-list for method output_type
+	1, // [1:3] is the sub-list for method input_type
+	1, // [1:1] is the sub-list for extension type_name
+	1, // [1:1] is the sub-list for extension extendee
+	0, // [0:1] is the sub-list for field type_name
 }
 
 func init() { file_devrpc_dev_proto_init() }
@@ -122,6 +236,30 @@ func file_devrpc_dev_proto_init() {
 				return nil
 			}
 		}
+		file_devrpc_dev_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*QuiescenceRequest); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_devrpc_dev_proto_msgTypes[2].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*QuiescenceResponse); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
 	}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
@@ -129,7 +267,7 @@ func file_devrpc_dev_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_devrpc_dev_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   1,
+			NumMessages:   3,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

lnrpc/devrpc/dev.pb.gw.go

@@ -66,6 +66,40 @@ func local_request_Dev_ImportGraph_0(ctx context.Context, marshaler runtime.Mars
 
 }
 
+func request_Dev_Quiesce_0(ctx context.Context, marshaler runtime.Marshaler, client DevClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq QuiescenceRequest
+	var metadata runtime.ServerMetadata
+
+	newReader, berr := utilities.IOReaderFactory(req.Body)
+	if berr != nil {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", berr)
+	}
+	if err := marshaler.NewDecoder(newReader()).Decode(&protoReq); err != nil && err != io.EOF {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := client.Quiesce(ctx, &protoReq, grpc.Header(&metadata.HeaderMD), grpc.Trailer(&metadata.TrailerMD))
+	return msg, metadata, err
+
+}
+
+func local_request_Dev_Quiesce_0(ctx context.Context, marshaler runtime.Marshaler, server DevServer, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq QuiescenceRequest
+	var metadata runtime.ServerMetadata
+
+	newReader, berr := utilities.IOReaderFactory(req.Body)
+	if berr != nil {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", berr)
+	}
+	if err := marshaler.NewDecoder(newReader()).Decode(&protoReq); err != nil && err != io.EOF {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := server.Quiesce(ctx, &protoReq)
+	return msg, metadata, err
+
+}
+
 // RegisterDevHandlerServer registers the http handlers for service Dev to "mux".
 // UnaryRPC     :call DevServer directly.
 // StreamingRPC :currently unsupported pending https://github.com/grpc/grpc-go/issues/906.
@@ -95,6 +129,29 @@ func RegisterDevHandlerServer(ctx context.Context, mux *runtime.ServeMux, server
 
 	})
 
+	mux.Handle("POST", pattern_Dev_Quiesce_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+		var stream runtime.ServerTransportStream
+		ctx = grpc.NewContextWithServerTransportStream(ctx, &stream)
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		rctx, err := runtime.AnnotateIncomingContext(ctx, mux, req, "/devrpc.Dev/Quiesce", runtime.WithHTTPPathPattern("/v2/dev/quiesce"))
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := local_request_Dev_Quiesce_0(rctx, inboundMarshaler, server, req, pathParams)
+		md.HeaderMD, md.TrailerMD = metadata.Join(md.HeaderMD, stream.Header()), metadata.Join(md.TrailerMD, stream.Trailer())
+		ctx = runtime.NewServerMetadataContext(ctx, md)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_Dev_Quiesce_0(ctx, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
 	return nil
 }
 
@@ -156,13 +213,37 @@ func RegisterDevHandlerClient(ctx context.Context, mux *runtime.ServeMux, client
 
 	})
 
+	mux.Handle("POST", pattern_Dev_Quiesce_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		rctx, err := runtime.AnnotateContext(ctx, mux, req, "/devrpc.Dev/Quiesce", runtime.WithHTTPPathPattern("/v2/dev/quiesce"))
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := request_Dev_Quiesce_0(rctx, inboundMarshaler, client, req, pathParams)
+		ctx = runtime.NewServerMetadataContext(ctx, md)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_Dev_Quiesce_0(ctx, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
 	return nil
 }
 
 var (
 	pattern_Dev_ImportGraph_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2}, []string{"v2", "dev", "importgraph"}, ""))
+
+	pattern_Dev_Quiesce_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2}, []string{"v2", "dev", "quiesce"}, ""))
 )
 
 var (
 	forward_Dev_ImportGraph_0 = runtime.ForwardResponseMessage
+
+	forward_Dev_Quiesce_0 = runtime.ForwardResponseMessage
 )

lnrpc/devrpc/dev.pb.json.go

@@ -46,4 +46,29 @@ func RegisterDevJSONCallbacks(registry map[string]func(ctx context.Context,
 		}
 		callback(string(respBytes), nil)
 	}
+
+	registry["devrpc.Dev.Quiesce"] = func(ctx context.Context,
+		conn *grpc.ClientConn, reqJSON string, callback func(string, error)) {
+
+		req := &QuiescenceRequest{}
+		err := marshaler.Unmarshal([]byte(reqJSON), req)
+		if err != nil {
+			callback("", err)
+			return
+		}
+
+		client := NewDevClient(conn)
+		resp, err := client.Quiesce(ctx, req)
+		if err != nil {
+			callback("", err)
+			return
+		}
+
+		respBytes, err := marshaler.Marshal(resp)
+		if err != nil {
+			callback("", err)
+			return
+		}
+		callback(string(respBytes), nil)
+	}
 }

lnrpc/devrpc/dev.proto

@@ -30,7 +30,25 @@ service Dev {
     used for development.
     */
     rpc ImportGraph (lnrpc.ChannelGraph) returns (ImportGraphResponse);
+
+    /*
+    Quiesce instructs a channel to initiate the quiescence (stfu) protocol. This
+    RPC is for testing purposes only. The commit that adds it will be removed
+    once interop is confirmed.
+    */
+    rpc Quiesce (QuiescenceRequest) returns (QuiescenceResponse);
 }
 
 message ImportGraphResponse {
 }
+
+message QuiescenceRequest {
+    // The channel point of the channel we wish to quiesce
+    lnrpc.ChannelPoint chan_id = 1;
+}
+
+message QuiescenceResponse {
+    // Indicates whether or not we hold the initiator role or not once the
+    // negotiation completes
+    bool initiator = 1;
+}

lnrpc/devrpc/dev.swagger.json

@@ -48,12 +48,63 @@
           "Dev"
         ]
       }
+    },
+    "/v2/dev/quiesce": {
+      "post": {
+        "summary": "Quiesce instructs a channel to initiate the quiescence (stfu) protocol. This\nRPC is for testing purposes only. The commit that adds it will be removed\nonce interop is confirmed.",
+        "operationId": "Dev_Quiesce",
+        "responses": {
+          "200": {
+            "description": "A successful response.",
+            "schema": {
+              "$ref": "#/definitions/devrpcQuiescenceResponse"
+            }
+          },
+          "default": {
+            "description": "An unexpected error response.",
+            "schema": {
+              "$ref": "#/definitions/rpcStatus"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "name": "body",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/devrpcQuiescenceRequest"
+            }
+          }
+        ],
+        "tags": [
+          "Dev"
+        ]
+      }
     }
   },
   "definitions": {
     "devrpcImportGraphResponse": {
       "type": "object"
     },
+    "devrpcQuiescenceRequest": {
+      "type": "object",
+      "properties": {
+        "chan_id": {
+          "$ref": "#/definitions/lnrpcChannelPoint",
+          "title": "The channel point of the channel we wish to quiesce"
+        }
+      }
+    },
+    "devrpcQuiescenceResponse": {
+      "type": "object",
+      "properties": {
+        "initiator": {
+          "type": "boolean",
+          "title": "Indicates whether or not we hold the initiator role or not once the\nnegotiation completes"
+        }
+      }
+    },
     "lnrpcChannelEdge": {
       "type": "object",
       "properties": {
@@ -116,6 +167,25 @@
       },
       "description": "Returns a new instance of the directed channel graph."
     },
+    "lnrpcChannelPoint": {
+      "type": "object",
+      "properties": {
+        "funding_txid_bytes": {
+          "type": "string",
+          "format": "byte",
+          "description": "Txid of the funding transaction. When using REST, this field must be\nencoded as base64."
+        },
+        "funding_txid_str": {
+          "type": "string",
+          "description": "Hex-encoded string representing the byte-reversed hash of the funding\ntransaction."
+        },
+        "output_index": {
+          "type": "integer",
+          "format": "int64",
+          "title": "The index of the output of the funding transaction"
+        }
+      }
+    },
     "lnrpcFeature": {
       "type": "object",
       "properties": {

lnrpc/devrpc/dev.yaml

@@ -6,3 +6,6 @@ http:
     - selector: devrpc.Dev.ImportGraph
       post: "/v2/dev/importgraph"
       body: "*"
+    - selector: devrpc.Dev.Quiesce
+      post: "/v2/dev/quiesce"
+      body: "*"

lnrpc/devrpc/dev_grpc.pb.go

@@ -23,6 +23,10 @@ type DevClient interface {
 	// ImportGraph imports a ChannelGraph into the graph database. Should only be
 	// used for development.
 	ImportGraph(ctx context.Context, in *lnrpc.ChannelGraph, opts ...grpc.CallOption) (*ImportGraphResponse, error)
+	// Quiesce instructs a channel to initiate the quiescence (stfu) protocol. This
+	// RPC is for testing purposes only. The commit that adds it will be removed
+	// once interop is confirmed.
+	Quiesce(ctx context.Context, in *QuiescenceRequest, opts ...grpc.CallOption) (*QuiescenceResponse, error)
 }
 
 type devClient struct {
@@ -42,6 +46,15 @@ func (c *devClient) ImportGraph(ctx context.Context, in *lnrpc.ChannelGraph, opt
 	return out, nil
 }
 
+func (c *devClient) Quiesce(ctx context.Context, in *QuiescenceRequest, opts ...grpc.CallOption) (*QuiescenceResponse, error) {
+	out := new(QuiescenceResponse)
+	err := c.cc.Invoke(ctx, "/devrpc.Dev/Quiesce", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 // DevServer is the server API for Dev service.
 // All implementations must embed UnimplementedDevServer
 // for forward compatibility
@@ -50,6 +63,10 @@ type DevServer interface {
 	// ImportGraph imports a ChannelGraph into the graph database. Should only be
 	// used for development.
 	ImportGraph(context.Context, *lnrpc.ChannelGraph) (*ImportGraphResponse, error)
+	// Quiesce instructs a channel to initiate the quiescence (stfu) protocol. This
+	// RPC is for testing purposes only. The commit that adds it will be removed
+	// once interop is confirmed.
+	Quiesce(context.Context, *QuiescenceRequest) (*QuiescenceResponse, error)
 	mustEmbedUnimplementedDevServer()
 }
 
@@ -60,6 +77,9 @@ type UnimplementedDevServer struct {
 func (UnimplementedDevServer) ImportGraph(context.Context, *lnrpc.ChannelGraph) (*ImportGraphResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method ImportGraph not implemented")
 }
+func (UnimplementedDevServer) Quiesce(context.Context, *QuiescenceRequest) (*QuiescenceResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method Quiesce not implemented")
+}
 func (UnimplementedDevServer) mustEmbedUnimplementedDevServer() {}
 
 // UnsafeDevServer may be embedded to opt out of forward compatibility for this service.
@@ -91,6 +111,24 @@ func _Dev_ImportGraph_Handler(srv interface{}, ctx context.Context, dec func(int
 	return interceptor(ctx, in, info, handler)
 }
 
+func _Dev_Quiesce_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(QuiescenceRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(DevServer).Quiesce(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/devrpc.Dev/Quiesce",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(DevServer).Quiesce(ctx, req.(*QuiescenceRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 // Dev_ServiceDesc is the grpc.ServiceDesc for Dev service.
 // It's only intended for direct use with grpc.RegisterService,
 // and not to be introspected or modified (even as a copy)
@@ -102,6 +140,10 @@ var Dev_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "ImportGraph",
 			Handler:    _Dev_ImportGraph_Handler,
 		},
+		{
+			MethodName: "Quiesce",
+			Handler:    _Dev_Quiesce_Handler,
+		},
 	},
 	Streams:  []grpc.StreamDesc{},
 	Metadata: "devrpc/dev.proto",

lnrpc/devrpc/dev_server.go

@@ -18,8 +18,10 @@ import (
 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channeldb/models"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/lncfg"
 	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"google.golang.org/grpc"
 	"gopkg.in/macaroon-bakery.v2/bakery"
@@ -40,6 +42,10 @@ var (
 			Entity: "offchain",
 			Action: "write",
 		}},
+		"/devrpc.Dev/Quiesce": {{
+			Entity: "offchain",
+			Action: "write",
+		}},
 	}
 )
 
@@ -56,6 +62,7 @@ type ServerShell struct {
 type Server struct {
 	started  int32 // To be used atomically.
 	shutdown int32 // To be used atomically.
+	quit     chan struct{}
 
 	// Required by the grpc-gateway/v2 library for forward compatibility.
 	// Must be after the atomically used variables to not break struct
@@ -78,7 +85,8 @@ func New(cfg *Config) (*Server, lnrpc.MacaroonPerms, error) {
 	// We don't create any new macaroons for this subserver, instead reuse
 	// existing onchain/offchain permissions.
 	server := &Server{
-		cfg: cfg,
+		quit: make(chan struct{}),
+		cfg:  cfg,
 	}
 
 	return server, macPermissions, nil
@@ -103,6 +111,8 @@ func (s *Server) Stop() error {
 		return nil
 	}
 
+	close(s.quit)
+
 	return nil
 }
 
@@ -342,3 +352,33 @@ func (s *Server) ImportGraph(ctx context.Context,
 
 	return &ImportGraphResponse{}, nil
 }
+
+// Quiesce initiates the quiescence process for the channel with the given
+// channel ID. This method will block until the channel is fully quiesced.
+func (s *Server) Quiesce(_ context.Context, in *QuiescenceRequest) (
+	*QuiescenceResponse, error) {
+
+	txid, err := lnrpc.GetChanPointFundingTxid(in.ChanId)
+	if err != nil {
+		return nil, err
+	}
+
+	op := wire.NewOutPoint(txid, in.ChanId.OutputIndex)
+	cid := lnwire.NewChanIDFromOutPoint(*op)
+	ln, err := s.cfg.Switch.GetLink(cid)
+	if err != nil {
+		return nil, err
+	}
+
+	select {
+	case result := <-ln.InitStfu():
+		mkResp := func(b lntypes.ChannelParty) *QuiescenceResponse {
+			return &QuiescenceResponse{Initiator: b.IsLocal()}
+		}
+
+		return fn.MapOk(mkResp)(result).Unpack()
+
+	case <-s.quit:
+		return nil, fmt.Errorf("server shutting down")
+	}
+}

lntest/rpc/harness_rpc.go

@@ -43,7 +43,7 @@ type HarnessRPC struct {
 	ChainKit         chainrpc.ChainKitClient
 	NeutrinoKit      neutrinorpc.NeutrinoKitClient
 	Peer             peersrpc.PeersClient
-	DevRPC           devrpc.DevClient
+	Dev              devrpc.DevClient
 
 	// Name is the HarnessNode's name.
 	Name string
@@ -75,7 +75,7 @@ func NewHarnessRPC(ctxt context.Context, t *testing.T, c *grpc.ClientConn,
 		ChainKit:         chainrpc.NewChainKitClient(c),
 		NeutrinoKit:      neutrinorpc.NewNeutrinoKitClient(c),
 		Peer:             peersrpc.NewPeersClient(c),
-		DevRPC:           devrpc.NewDevClient(c),
+		Dev:              devrpc.NewDevClient(c),
 		Name:             name,
 	}
 

lntest/rpc/lnd.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/devrpc"
 	"github.com/stretchr/testify/require"
 )
 
@@ -730,3 +731,17 @@ func (h *HarnessRPC) LookupHtlcResolutionAssertErr(
 
 	return err
 }
+
+// Quiesce makes an RPC call to the node's Quiesce method and returns the
+// response.
+func (h *HarnessRPC) Quiesce(
+	req *devrpc.QuiescenceRequest) *devrpc.QuiescenceResponse {
+
+	ctx, cancel := context.WithTimeout(h.runCtx, DefaultTimeout)
+	defer cancel()
+
+	res, err := h.Dev.Quiesce(ctx, req)
+	h.NoError(err, "Quiesce returned an error")
+
+	return res
+}

lnwire/features.go

@@ -171,6 +171,16 @@ const (
 	// sender-generated preimages according to BOLT XX.
 	AMPOptional FeatureBit = 31
 
+	// QuiescenceRequired is a required feature bit that denotes that a
+	// connection established with this node must support the quiescence
+	// protocol if it wants to have a channel relationship.
+	QuiescenceRequired FeatureBit = 34
+
+	// QuiescenceOptional is an optional feature bit that denotes that a
+	// connection established with this node is permitted to use the
+	// quiescence protocol.
+	QuiescenceOptional FeatureBit = 35
+
 	// ExplicitChannelTypeRequired is a required bit that denotes that a
 	// connection established with this node is to use explicit channel
 	// commitment types for negotiation instead of the existing implicit
@@ -335,6 +345,8 @@ var Features = map[FeatureBit]string{
 	WumboChannelsOptional:                "wumbo-channels",
 	AMPRequired:                          "amp",
 	AMPOptional:                          "amp",
+	QuiescenceRequired:                   "quiescence",
+	QuiescenceOptional:                   "quiescence",
 	PaymentMetadataOptional:              "payment-metadata",
 	PaymentMetadataRequired:              "payment-metadata",
 	ExplicitChannelTypeOptional:          "explicit-commitment-type",

lnwire/message.go

@@ -63,6 +63,25 @@ const (
 	MsgKickoffSig                          = 777
 )
 
+// IsChannelUpdate is a filter function that discerns channel update messages
+// from the other messages in the Lightning Network Protocol.
+func (t MessageType) IsChannelUpdate() bool {
+	switch t {
+	case MsgUpdateAddHTLC:
+		return true
+	case MsgUpdateFulfillHTLC:
+		return true
+	case MsgUpdateFailHTLC:
+		return true
+	case MsgUpdateFailMalformedHTLC:
+		return true
+	case MsgUpdateFee:
+		return true
+	default:
+		return false
+	}
+}
+
 // ErrorEncodeMessage is used when failed to encode the message payload.
 func ErrorEncodeMessage(err error) error {
 	return fmt.Errorf("failed to encode message to buffer, got %w", err)

peer/brontide.go

@@ -411,6 +411,10 @@ type Config struct {
 	// invalid.
 	DisallowRouteBlinding bool
 
+	// DisallowQuiescence is a flag that indicates whether the Brontide
+	// should have the quiescence feature disabled.
+	DisallowQuiescence bool
+
 	// MaxFeeExposure limits the number of outstanding fees in a channel.
 	// This value will be passed to created links.
 	MaxFeeExposure lnwire.MilliSatoshi
@@ -1324,6 +1328,8 @@ func (p *Brontide) addLink(chanPoint *wire.OutPoint,
 		DisallowRouteBlinding:   p.cfg.DisallowRouteBlinding,
 		MaxFeeExposure:          p.cfg.MaxFeeExposure,
 		ShouldFwdExpEndorsement: p.cfg.ShouldFwdExpEndorsement,
+		DisallowQuiescence: p.cfg.DisallowQuiescence ||
+			!p.remoteFeatures.HasFeature(lnwire.QuiescenceOptional),
 	}
 
 	// Before adding our new link, purge the switch of any pending or live

peer/test_utils.go

@@ -24,6 +24,7 @@ import (
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lntest/channels"
 	"github.com/lightningnetwork/lnd/lntest/mock"
+	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/lnwire"
@@ -477,6 +478,14 @@ func (m *mockUpdateHandler) OnCommitOnce(
 
 	hook()
 }
+func (m *mockUpdateHandler) InitStfu() <-chan fn.Result[lntypes.ChannelParty] {
+	// TODO(proofofkeags): Implement
+	c := make(chan fn.Result[lntypes.ChannelParty], 1)
+
+	c <- fn.Errf[lntypes.ChannelParty]("InitStfu not yet implemented")
+
+	return c
+}
 
 func newMockConn(t *testing.T, expectedMessages int) *mockMessageConn {
 	return &mockMessageConn{

server.go

@@ -587,6 +587,7 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 		NoTaprootOverlay:          !cfg.ProtocolOptions.TaprootOverlayChans,
 		NoRouteBlinding:           cfg.ProtocolOptions.NoRouteBlinding(),
 		NoExperimentalEndorsement: cfg.ProtocolOptions.NoExperimentalEndorsement(),
+		NoQuiescence:              cfg.ProtocolOptions.NoQuiescence(),
 	})
 	if err != nil {
 		return nil, err
@@ -4214,6 +4215,7 @@ func (s *server) peerConnected(conn net.Conn, connReq *connmgr.ConnReq,
 		RequestAlias:           s.aliasMgr.RequestAlias,
 		AddLocalAlias:          s.aliasMgr.AddLocalAlias,
 		DisallowRouteBlinding:  s.cfg.ProtocolOptions.NoRouteBlinding(),
+		DisallowQuiescence:     s.cfg.ProtocolOptions.NoQuiescence(),
 		MaxFeeExposure:         thresholdMSats,
 		Quit:                   s.quit,
 		AuxLeafStore:           s.implCfg.AuxLeafStore,

subrpcserver_config.go

@@ -346,6 +346,10 @@ func (s *subRPCServerConfigs) PopulateDependencies(cfg *Config,
 				reflect.ValueOf(graphDB),
 			)
 
+			subCfgValue.FieldByName("Switch").Set(
+				reflect.ValueOf(htlcSwitch),
+			)
+
 		case *peersrpc.Config:
 			subCfgValue := extractReflectValue(subCfg)