Merge pull request #9880 from yyforyongyu/accessman

Improve access control in peer connections

accessman.go

@@ -21,20 +21,24 @@ type accessMan struct {
 	// the server mutex.
 	banScoreMtx sync.RWMutex
 
-	// peerCounts is a mapping from remote public key to {bool, uint64}
-	// where the bool indicates that we have an open/closed channel with
-	// the peer and where the uint64 indicates the number of pending-open
+	// peerChanInfo is a mapping from remote public key to {bool, uint64}
+	// where the bool indicates that we have an open/closed channel with the
+	// peer and where the uint64 indicates the number of pending-open
 	// channels we currently have with them. This mapping will be used to
 	// determine access permissions for the peer. The map key is the
 	// string-version of the serialized public key.
 	//
 	// NOTE: This MUST be accessed with the banScoreMtx held.
-	peerCounts map[string]channeldb.ChanCount
+	peerChanInfo map[string]channeldb.ChanCount
 
 	// peerScores stores each connected peer's access status. The map key
 	// is the string-version of the serialized public key.
 	//
 	// NOTE: This MUST be accessed with the banScoreMtx held.
+	//
+	// TODO(yy): unify `peerScores` and `peerChanInfo` - there's no need to
+	// create two maps tracking essentially the same info. `numRestricted`
+	// can also be derived from `peerChanInfo`.
 	peerScores map[string]peerSlotStatus
 
 	// numRestricted tracks the number of peers with restricted access in
@@ -44,7 +48,7 @@ type accessMan struct {
 
 type accessManConfig struct {
 	// initAccessPerms checks the channeldb for initial access permissions
-	// and then populates the peerCounts and peerScores maps.
+	// and then populates the peerChanInfo and peerScores maps.
 	initAccessPerms func() (map[string]channeldb.ChanCount, error)
 
 	// shouldDisconnect determines whether we should disconnect a peer or
@@ -57,9 +61,9 @@ type accessManConfig struct {
 
 func newAccessMan(cfg *accessManConfig) (*accessMan, error) {
 	a := &accessMan{
-		cfg:        cfg,
-		peerCounts: make(map[string]channeldb.ChanCount),
-		peerScores: make(map[string]peerSlotStatus),
+		cfg:          cfg,
+		peerChanInfo: make(map[string]channeldb.ChanCount),
+		peerScores:   make(map[string]peerSlotStatus),
 	}
 
 	counts, err := a.cfg.initAccessPerms()
@@ -67,16 +71,58 @@ func newAccessMan(cfg *accessManConfig) (*accessMan, error) {
 		return nil, err
 	}
 
-	// We'll populate the server's peerCounts map with the counts fetched
+	// We'll populate the server's peerChanInfo map with the counts fetched
 	// via initAccessPerms. Also note that we haven't yet connected to the
 	// peers.
-	maps.Copy(a.peerCounts, counts)
+	maps.Copy(a.peerChanInfo, counts)
 
 	acsmLog.Info("Access Manager initialized")
 
 	return a, nil
 }
 
+// hasPeer checks whether a given peer already exists in the internal maps.
+func (a *accessMan) hasPeer(ctx context.Context,
+	pub string) (peerAccessStatus, bool) {
+
+	// Lock banScoreMtx for reading so that we can read the banning maps
+	// below.
+	a.banScoreMtx.RLock()
+	defer a.banScoreMtx.RUnlock()
+
+	count, found := a.peerChanInfo[pub]
+	if found {
+		if count.HasOpenOrClosedChan {
+			acsmLog.DebugS(ctx, "Peer has open/closed channel, "+
+				"assigning protected access")
+
+			// Exit early if the peer is no longer restricted.
+			return peerStatusProtected, true
+		}
+
+		if count.PendingOpenCount != 0 {
+			acsmLog.DebugS(ctx, "Peer has pending channel(s), "+
+				"assigning temporary access")
+
+			// Exit early if the peer is no longer restricted.
+			return peerStatusTemporary, true
+		}
+
+		return peerStatusRestricted, true
+	}
+
+	// Check if the peer is found in the scores map.
+	status, found := a.peerScores[pub]
+	if found {
+		acsmLog.DebugS(ctx, "Peer already has access", "access",
+			status.state)
+
+		return status.state, true
+	}
+
+	return peerStatusRestricted, false
+}
+
 // assignPeerPerms assigns a new peer its permissions. This does not track the
 // access in the maps. This is intentional.
 func (a *accessMan) assignPeerPerms(remotePub *btcec.PublicKey) (
@@ -91,31 +137,15 @@ func (a *accessMan) assignPeerPerms(remotePub *btcec.PublicKey) (
 	acsmLog.DebugS(ctx, "Assigning permissions")
 
 	// Default is restricted unless the below filters say otherwise.
-	access := peerStatusRestricted
+	access, peerExist := a.hasPeer(ctx, peerMapKey)
 
-	// Lock banScoreMtx for reading so that we can update the banning maps
-	// below.
-	a.banScoreMtx.RLock()
-	if count, found := a.peerCounts[peerMapKey]; found {
-		if count.HasOpenOrClosedChan {
-			acsmLog.DebugS(ctx, "Peer has open/closed channel, "+
-				"assigning protected access")
-
-			access = peerStatusProtected
-		} else if count.PendingOpenCount != 0 {
-			acsmLog.DebugS(ctx, "Peer has pending channel(s), "+
-				"assigning temporary access")
-
-			access = peerStatusTemporary
-		}
-	}
-	a.banScoreMtx.RUnlock()
-
-	// Exit early if the peer status is no longer restricted.
+	// Exit early if the peer is not restricted.
 	if access != peerStatusRestricted {
 		return access, nil
 	}
 
+	// If we are here, it means the peer has peerStatusRestricted.
+	//
 	// Check whether this peer is banned.
 	shouldDisconnect, err := a.cfg.shouldDisconnect(remotePub)
 	if err != nil {
@@ -138,6 +168,12 @@ func (a *accessMan) assignPeerPerms(remotePub *btcec.PublicKey) (
 	// peer.
 	acsmLog.DebugS(ctx, "Peer has no channels, assigning restricted access")
 
+	// If this is an existing peer, there's no need to check for slot limit.
+	if peerExist {
+		acsmLog.DebugS(ctx, "Skipped slot check for existing peer")
+		return access, nil
+	}
+
 	a.banScoreMtx.RLock()
 	defer a.banScoreMtx.RUnlock()
 
@@ -187,11 +223,11 @@ func (a *accessMan) newPendingOpenChan(remotePub *btcec.PublicKey) error {
 
 	case peerStatusTemporary:
 		// If this peer's access status is temporary, we'll need to
-		// update the peerCounts map. The peer's access status will stay
-		// temporary.
-		peerCount, found := a.peerCounts[peerMapKey]
+		// update the peerChanInfo map. The peer's access status will
+		// stay temporary.
+		peerCount, found := a.peerChanInfo[peerMapKey]
 		if !found {
-			// Error if we did not find any info in peerCounts.
+			// Error if we did not find any info in peerChanInfo.
 			acsmLog.ErrorS(ctx, "Pending peer info not found",
 				ErrNoPendingPeerInfo)
 
@@ -200,7 +236,7 @@ func (a *accessMan) newPendingOpenChan(remotePub *btcec.PublicKey) error {
 
 		// Increment the pending channel amount.
 		peerCount.PendingOpenCount += 1
-		a.peerCounts[peerMapKey] = peerCount
+		a.peerChanInfo[peerMapKey] = peerCount
 
 		acsmLog.DebugS(ctx, "Peer is temporary, incremented "+
 			"pending count",
@@ -210,13 +246,13 @@ func (a *accessMan) newPendingOpenChan(remotePub *btcec.PublicKey) error {
 		// If the peer's access status is restricted, then we can
 		// transition it to a temporary-access peer. We'll need to
 		// update numRestricted and also peerScores. We'll also need to
-		// update peerCounts.
+		// update peerChanInfo.
 		peerCount := channeldb.ChanCount{
 			HasOpenOrClosedChan: false,
 			PendingOpenCount:    1,
 		}
 
-		a.peerCounts[peerMapKey] = peerCount
+		a.peerChanInfo[peerMapKey] = peerCount
 
 		// A restricted-access slot has opened up.
 		oldRestricted := a.numRestricted
@@ -277,12 +313,12 @@ func (a *accessMan) newPendingCloseChan(remotePub *btcec.PublicKey) error {
 	case peerStatusTemporary:
 		// If this peer is temporary, we need to check if it will
 		// revert to a restricted-access peer.
-		peerCount, found := a.peerCounts[peerMapKey]
+		peerCount, found := a.peerChanInfo[peerMapKey]
 		if !found {
 			acsmLog.ErrorS(ctx, "Pending peer info not found",
 				ErrNoPendingPeerInfo)
 
-			// Error if we did not find any info in peerCounts.
+			// Error if we did not find any info in peerChanInfo.
 			return ErrNoPendingPeerInfo
 		}
 
@@ -293,8 +329,8 @@ func (a *accessMan) newPendingCloseChan(remotePub *btcec.PublicKey) error {
 			"pending_count", currentNumPending)
 
 		if currentNumPending == 0 {
-			// Remove the entry from peerCounts.
-			delete(a.peerCounts, peerMapKey)
+			// Remove the entry from peerChanInfo.
+			delete(a.peerChanInfo, peerMapKey)
 
 			// If this is the only pending-open channel for this
 			// peer and it's getting removed, attempt to demote
@@ -334,7 +370,7 @@ func (a *accessMan) newPendingCloseChan(remotePub *btcec.PublicKey) error {
 		// Else, we don't need to demote this peer since it has other
 		// pending-open channels with us.
 		peerCount.PendingOpenCount = currentNumPending
-		a.peerCounts[peerMapKey] = peerCount
+		a.peerChanInfo[peerMapKey] = peerCount
 
 		acsmLog.DebugS(ctx, "Peer still has other pending channels",
 			"pending_count", currentNumPending)
@@ -394,9 +430,9 @@ func (a *accessMan) newOpenChan(remotePub *btcec.PublicKey) error {
 	case peerStatusTemporary:
 		// If the peer's state is temporary, we'll upgrade the peer to
 		// a protected peer.
-		peerCount, found := a.peerCounts[peerMapKey]
+		peerCount, found := a.peerChanInfo[peerMapKey]
 		if !found {
-			// Error if we did not find any info in peerCounts.
+			// Error if we did not find any info in peerChanInfo.
 			acsmLog.ErrorS(ctx, "Pending peer info not found",
 				ErrNoPendingPeerInfo)
 
@@ -404,7 +440,9 @@ func (a *accessMan) newOpenChan(remotePub *btcec.PublicKey) error {
 		}
 
 		peerCount.HasOpenOrClosedChan = true
-		a.peerCounts[peerMapKey] = peerCount
+		peerCount.PendingOpenCount -= 1
+
+		a.peerChanInfo[peerMapKey] = peerCount
 
 		newStatus := peerSlotStatus{
 			state: peerStatusProtected,
@@ -443,11 +481,15 @@ func (a *accessMan) newOpenChan(remotePub *btcec.PublicKey) error {
 	}
 }
 
-// checkIncomingConnBanScore checks whether, given the remote's public hex-
+// checkAcceptIncomingConn checks whether, given the remote's public hex-
 // encoded key, we should not accept this incoming connection or immediately
 // disconnect. This does not assign to the server's peerScores maps. This is
 // just an inbound filter that the brontide listeners use.
-func (a *accessMan) checkIncomingConnBanScore(remotePub *btcec.PublicKey) (
+//
+// TODO(yy): We should also consider removing this `checkAcceptIncomingConn`
+// check as a) it doesn't check for ban score; and b) we should, and already
+// have this check when we handle incoming connection in `InboundPeerConnected`.
+func (a *accessMan) checkAcceptIncomingConn(remotePub *btcec.PublicKey) (
 	bool, error) {
 
 	ctx := btclog.WithCtx(
@@ -461,42 +503,51 @@ func (a *accessMan) checkIncomingConnBanScore(remotePub *btcec.PublicKey) (
 	a.banScoreMtx.RLock()
 	defer a.banScoreMtx.RUnlock()
 
-	if _, found := a.peerCounts[peerMapKey]; !found {
-		acsmLog.DebugS(ctx, "Peer not found in counts, "+
-			"checking restricted slots")
+	_, found := a.peerChanInfo[peerMapKey]
 
-		// Check numRestricted to see if there is an available slot. In
-		// the future, it's possible to add better heuristics.
-		if a.numRestricted < a.cfg.maxRestrictedSlots {
-			// There is an available slot.
-			acsmLog.DebugS(ctx, "Restricted slot available, "+
-				"accepting",
-				"num_restricted", a.numRestricted,
-				"max_restricted", a.cfg.maxRestrictedSlots)
+	// Exit early if found.
+	if found {
+		acsmLog.DebugS(ctx, "Peer found (protected/temporary), "+
+			"accepting")
 
-			return true, nil
-		}
-
-		// If there are no slots left, then we reject this connection.
-		acsmLog.WarnS(ctx, "No restricted slots available, "+
-			"rejecting",
-			ErrNoMoreRestrictedAccessSlots,
-			"num_restricted", a.numRestricted,
-			"max_restricted", a.cfg.maxRestrictedSlots)
-
-		return false, ErrNoMoreRestrictedAccessSlots
+		return true, nil
 	}
 
-	// Else, the peer is either protected or temporary.
-	acsmLog.DebugS(ctx, "Peer found (protected/temporary), accepting")
+	_, found = a.peerScores[peerMapKey]
 
-	return true, nil
+	// Exit early if found.
+	if found {
+		acsmLog.DebugS(ctx, "Found existing peer, accepting")
+
+		return true, nil
+	}
+
+	acsmLog.DebugS(ctx, "Peer not found in counts, checking restricted "+
+		"slots")
+
+	// Check numRestricted to see if there is an available slot. In
+	// the future, it's possible to add better heuristics.
+	if a.numRestricted < a.cfg.maxRestrictedSlots {
+		// There is an available slot.
+		acsmLog.DebugS(ctx, "Restricted slot available, accepting ",
+			"num_restricted", a.numRestricted, "max_restricted",
+			a.cfg.maxRestrictedSlots)
+
+		return true, nil
+	}
+
+	// If there are no slots left, then we reject this connection.
+	acsmLog.WarnS(ctx, "No restricted slots available, rejecting ",
+		ErrNoMoreRestrictedAccessSlots, "num_restricted",
+		a.numRestricted, "max_restricted", a.cfg.maxRestrictedSlots)
+
+	return false, ErrNoMoreRestrictedAccessSlots
 }
 
 // addPeerAccess tracks a peer's access in the maps. This should be called when
 // the peer has fully connected.
 func (a *accessMan) addPeerAccess(remotePub *btcec.PublicKey,
-	access peerAccessStatus) {
+	access peerAccessStatus, inbound bool) {
 
 	ctx := btclog.WithCtx(
 		context.TODO(), lnutils.LogPubKey("peer", remotePub),
@@ -510,34 +561,64 @@ func (a *accessMan) addPeerAccess(remotePub *btcec.PublicKey,
 
 	peerMapKey := string(remotePub.SerializeCompressed())
 
+	// Exit early if this is an existing peer, which means it won't take
+	// another slot.
+	_, found := a.peerScores[peerMapKey]
+	if found {
+		acsmLog.DebugS(ctx, "Skipped taking restricted slot for "+
+			"existing peer")
+
+		return
+	}
+
 	a.peerScores[peerMapKey] = peerSlotStatus{state: access}
 
-	// Increment numRestricted.
-	if access == peerStatusRestricted {
+	// Exit early if this is not a restricted peer.
+	if access != peerStatusRestricted {
+		acsmLog.DebugS(ctx, "Skipped taking restricted slot as peer "+
+			"already has access", "access", access)
+
+		return
+	}
+
+	// Increment numRestricted if this is an inbound connection.
+	if inbound {
 		oldRestricted := a.numRestricted
 		a.numRestricted++
 
 		acsmLog.DebugS(ctx, "Incremented restricted slots",
 			"old_restricted", oldRestricted,
 			"new_restricted", a.numRestricted)
+
+		return
 	}
+
+	// Otherwise, this is a newly created outbound connection. We won't
+	// place any restriction on it, instead, we will do a hot upgrade here
+	// to move it from restricted to temporary.
+	peerCount := channeldb.ChanCount{
+		HasOpenOrClosedChan: false,
+		PendingOpenCount:    0,
+	}
+
+	a.peerChanInfo[peerMapKey] = peerCount
+	a.peerScores[peerMapKey] = peerSlotStatus{
+		state: peerStatusTemporary,
+	}
+
+	acsmLog.InfoS(ctx, "Upgraded outbound peer: restricted -> temporary")
 }
 
 // removePeerAccess removes the peer's access from the maps. This should be
 // called when the peer has been disconnected.
-func (a *accessMan) removePeerAccess(remotePub *btcec.PublicKey) {
+func (a *accessMan) removePeerAccess(peerPubKey string) {
+	ctx := btclog.WithCtx(context.TODO(), "peer", peerPubKey)
+	acsmLog.DebugS(ctx, "Removing access:")
+
 	a.banScoreMtx.Lock()
 	defer a.banScoreMtx.Unlock()
 
-	ctx := btclog.WithCtx(
-		context.TODO(), lnutils.LogPubKey("peer", remotePub),
-	)
-
-	acsmLog.DebugS(ctx, "Removing peer access")
-
-	peerMapKey := string(remotePub.SerializeCompressed())
-
-	status, found := a.peerScores[peerMapKey]
+	status, found := a.peerScores[peerPubKey]
 	if !found {
 		acsmLog.InfoS(ctx, "Peer score not found during removal")
 		return
@@ -554,7 +635,31 @@ func (a *accessMan) removePeerAccess(remotePub *btcec.PublicKey) {
 			"new_restricted", a.numRestricted)
 	}
 
-	acsmLog.TraceS(ctx, "Deleting peer from peerScores")
+	acsmLog.TraceS(ctx, "Deleting from peerScores:")
 
-	delete(a.peerScores, peerMapKey)
+	delete(a.peerScores, peerPubKey)
+
+	// We now check whether this peer has channels with us or not.
+	info, found := a.peerChanInfo[peerPubKey]
+	if !found {
+		acsmLog.DebugS(ctx, "Chan info not found during removal:")
+		return
+	}
+
+	// Exit early if the peer has channel(s) with us.
+	if info.HasOpenOrClosedChan {
+		acsmLog.DebugS(ctx, "Skipped removing peer with channels:")
+		return
+	}
+
+	// Skip removing the peer if it has pending open/close with us.
+	if info.PendingOpenCount != 0 {
+		acsmLog.DebugS(ctx, "Skipped removing peer with pending "+
+			"channels:")
+		return
+	}
+
+	// Given this peer has no channels with us, we can now remove it.
+	delete(a.peerChanInfo, peerPubKey)
+	acsmLog.TraceS(ctx, "Removed peer from peerChanInfo:")
 }

accessman_test.go

@@ -1,6 +1,7 @@
 package lnd
 
 import (
+	"context"
 	"testing"
 
 	"github.com/btcsuite/btcd/btcec/v2"
@@ -15,7 +16,7 @@ func assertInboundConnection(t *testing.T, a *accessMan,
 
 	remotePubSer := string(remotePub.SerializeCompressed())
 
-	isSlotAvailable, err := a.checkIncomingConnBanScore(remotePub)
+	isSlotAvailable, err := a.checkAcceptIncomingConn(remotePub)
 	require.NoError(t, err)
 	require.True(t, isSlotAvailable)
 
@@ -23,7 +24,7 @@ func assertInboundConnection(t *testing.T, a *accessMan,
 	require.NoError(t, err)
 	require.Equal(t, status, peerAccess)
 
-	a.addPeerAccess(remotePub, peerAccess)
+	a.addPeerAccess(remotePub, peerAccess, true)
 	peerScore, ok := a.peerScores[remotePubSer]
 	require.True(t, ok)
 	require.Equal(t, status, peerScore.state)
@@ -63,18 +64,25 @@ func TestAccessManRestrictedSlots(t *testing.T) {
 	peerKey3 := peerPriv3.PubKey()
 	peerKeySer3 := string(peerKey3.SerializeCompressed())
 
+	var (
+		peer1PendingCount = 0
+		peer2PendingCount = 1
+		peer3PendingCount = 1
+	)
+
 	initPerms := func() (map[string]channeldb.ChanCount, error) {
 		return map[string]channeldb.ChanCount{
 			peerKeySer1: {
 				HasOpenOrClosedChan: true,
+				PendingOpenCount:    uint64(peer1PendingCount),
 			},
 			peerKeySer2: {
 				HasOpenOrClosedChan: true,
-				PendingOpenCount:    1,
+				PendingOpenCount:    uint64(peer2PendingCount),
 			},
 			peerKeySer3: {
 				HasOpenOrClosedChan: false,
-				PendingOpenCount:    1,
+				PendingOpenCount:    uint64(peer3PendingCount),
 			},
 		}, nil
 	}
@@ -92,25 +100,25 @@ func TestAccessManRestrictedSlots(t *testing.T) {
 	a, err := newAccessMan(cfg)
 	require.NoError(t, err)
 
-	// Check that the peerCounts map is correctly populated with three
+	// Check that the peerChanInfo map is correctly populated with three
 	// peers.
 	require.Equal(t, 0, int(a.numRestricted))
-	require.Equal(t, 3, len(a.peerCounts))
+	require.Equal(t, 3, len(a.peerChanInfo))
 
-	peerCount1, ok := a.peerCounts[peerKeySer1]
+	peerCount1, ok := a.peerChanInfo[peerKeySer1]
 	require.True(t, ok)
 	require.True(t, peerCount1.HasOpenOrClosedChan)
-	require.Equal(t, 0, int(peerCount1.PendingOpenCount))
+	require.Equal(t, peer1PendingCount, int(peerCount1.PendingOpenCount))
 
-	peerCount2, ok := a.peerCounts[peerKeySer2]
+	peerCount2, ok := a.peerChanInfo[peerKeySer2]
 	require.True(t, ok)
 	require.True(t, peerCount2.HasOpenOrClosedChan)
-	require.Equal(t, 1, int(peerCount2.PendingOpenCount))
+	require.Equal(t, peer2PendingCount, int(peerCount2.PendingOpenCount))
 
-	peerCount3, ok := a.peerCounts[peerKeySer3]
+	peerCount3, ok := a.peerChanInfo[peerKeySer3]
 	require.True(t, ok)
 	require.False(t, peerCount3.HasOpenOrClosedChan)
-	require.Equal(t, 1, int(peerCount3.PendingOpenCount))
+	require.Equal(t, peer3PendingCount, int(peerCount3.PendingOpenCount))
 
 	// We'll now start to connect the peers. We'll add a new fourth peer
 	// that will take up the restricted slot. The first three peers should
@@ -120,7 +128,7 @@ func TestAccessManRestrictedSlots(t *testing.T) {
 	peerKey4 := peerPriv4.PubKey()
 
 	// Follow the normal process of an incoming connection. We check if we
-	// can accommodate this peer in checkIncomingConnBanScore and then we
+	// can accommodate this peer in checkAcceptIncomingConn and then we
 	// assign its access permissions and then insert into the map.
 	assertInboundConnection(t, a, peerKey4, peerStatusRestricted)
 
@@ -134,11 +142,26 @@ func TestAccessManRestrictedSlots(t *testing.T) {
 	require.NoError(t, err)
 	assertAccessState(t, a, peerKey4, peerStatusTemporary)
 
+	// Assert that accessman's internal state is updated with peer4. We
+	// expect this new peer to have 1 pending open count.
+	peerCount4, ok := a.peerChanInfo[string(peerKey4.SerializeCompressed())]
+	require.True(t, ok)
+	require.False(t, peerCount4.HasOpenOrClosedChan)
+	require.Equal(t, 1, int(peerCount4.PendingOpenCount))
+
 	// Check that an open channel promotes the temporary peer.
 	err = a.newOpenChan(peerKey3)
 	require.NoError(t, err)
 	assertAccessState(t, a, peerKey3, peerStatusProtected)
 
+	// Assert that accessman's internal state is updated with peer3. We
+	// expect this existing peer to decrement its pending open count and the
+	// flag `HasOpenOrClosedChan` should be true.
+	peerCount3, ok = a.peerChanInfo[peerKeySer3]
+	require.True(t, ok)
+	require.True(t, peerCount3.HasOpenOrClosedChan)
+	require.Equal(t, peer3PendingCount-1, int(peerCount3.PendingOpenCount))
+
 	// We should be able to accommodate a new peer.
 	peerPriv5, err := btcec.NewPrivateKey()
 	require.NoError(t, err)
@@ -150,6 +173,10 @@ func TestAccessManRestrictedSlots(t *testing.T) {
 	// peer.
 	err = a.newPendingCloseChan(peerKey4)
 	require.ErrorIs(t, err, ErrNoMoreRestrictedAccessSlots)
+
+	// Assert that peer4 is removed.
+	_, ok = a.peerChanInfo[string(peerKey4.SerializeCompressed())]
+	require.False(t, ok)
 }
 
 // TestAssignPeerPerms asserts that the peer's access status is correctly
@@ -250,9 +277,8 @@ func TestAssignPeerPerms(t *testing.T) {
 			expectedErr:      ErrGossiperBan,
 		},
 		// peer6 has no channel with us, and we expect it to have a
-		// restricted status. We also expect the error
-		// `ErrNoMoreRestrictedAccessSlots` to be returned given
-		// we only allow 1 restricted peer in this test.
+		// restricted status. Since this peer is seen, we don't expect
+		// the error `ErrNoMoreRestrictedAccessSlots` to be returned.
 		{
 			name:    "peer with no channels and restricted",
 			peerPub: genPeerPub(),
@@ -264,7 +290,7 @@ func TestAssignPeerPerms(t *testing.T) {
 			numRestricted:    1,
 
 			expectedStatus: peerStatusRestricted,
-			expectedErr:    ErrNoMoreRestrictedAccessSlots,
+			expectedErr:    nil,
 		},
 	}
 
@@ -394,3 +420,394 @@ func TestAssignPeerPermsBypassRestriction(t *testing.T) {
 		})
 	}
 }
+
+// TestAssignPeerPermsBypassExisting asserts that when the peer is a
+// pre-existing peer, it won't be restricted.
+func TestAssignPeerPermsBypassExisting(t *testing.T) {
+	t.Parallel()
+
+	// genPeerPub is a helper closure that generates a random public key.
+	genPeerPub := func() *btcec.PublicKey {
+		peerPriv, err := btcec.NewPrivateKey()
+		require.NoError(t, err)
+
+		return peerPriv.PubKey()
+	}
+
+	// peer1 exists in `peerChanInfo` map.
+	peer1 := genPeerPub()
+	peer1Str := string(peer1.SerializeCompressed())
+
+	// peer2 exists in `peerScores` map.
+	peer2 := genPeerPub()
+	peer2Str := string(peer2.SerializeCompressed())
+
+	// peer3 is a new peer.
+	peer3 := genPeerPub()
+
+	// Create params to init the accessman.
+	initPerms := func() (map[string]channeldb.ChanCount, error) {
+		return map[string]channeldb.ChanCount{
+			peer1Str: {},
+		}, nil
+	}
+
+	disconnect := func(*btcec.PublicKey) (bool, error) {
+		return false, nil
+	}
+
+	cfg := &accessManConfig{
+		initAccessPerms:    initPerms,
+		shouldDisconnect:   disconnect,
+		maxRestrictedSlots: 0,
+	}
+
+	a, err := newAccessMan(cfg)
+	require.NoError(t, err)
+
+	// Add peer2 to the `peerScores`.
+	a.peerScores[peer2Str] = peerSlotStatus{
+		state: peerStatusTemporary,
+	}
+
+	// Assigning to peer1 should not return an error.
+	status, err := a.assignPeerPerms(peer1)
+	require.NoError(t, err)
+	require.Equal(t, peerStatusRestricted, status)
+
+	// Assigning to peer2 should not return an error.
+	status, err = a.assignPeerPerms(peer2)
+	require.NoError(t, err)
+	require.Equal(t, peerStatusTemporary, status)
+
+	// Assigning to peer3 should return an error.
+	status, err = a.assignPeerPerms(peer3)
+	require.ErrorIs(t, err, ErrNoMoreRestrictedAccessSlots)
+	require.Equal(t, peerStatusRestricted, status)
+}
+
+// TestHasPeer asserts `hasPeer` returns the correct results.
+func TestHasPeer(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+
+	// Create a testing accessMan.
+	a := &accessMan{
+		peerChanInfo: make(map[string]channeldb.ChanCount),
+		peerScores:   make(map[string]peerSlotStatus),
+	}
+
+	// peer1 exists with an open channel.
+	peer1 := "peer1"
+	a.peerChanInfo[peer1] = channeldb.ChanCount{
+		HasOpenOrClosedChan: true,
+	}
+	peer1Access := peerStatusProtected
+
+	// peer2 exists with a pending channel.
+	peer2 := "peer2"
+	a.peerChanInfo[peer2] = channeldb.ChanCount{
+		PendingOpenCount: 1,
+	}
+	peer2Access := peerStatusTemporary
+
+	// peer3 exists without any channels.
+	peer3 := "peer3"
+	a.peerChanInfo[peer3] = channeldb.ChanCount{}
+	peer3Access := peerStatusRestricted
+
+	// peer4 exists with a score.
+	peer4 := "peer4"
+	peer4Access := peerStatusTemporary
+	a.peerScores[peer4] = peerSlotStatus{state: peer4Access}
+
+	// peer5 doesn't exist.
+	peer5 := "peer5"
+
+	// We now assert `hasPeer` returns the correct results.
+	//
+	// peer1 should be found with peerStatusProtected.
+	access, found := a.hasPeer(ctx, peer1)
+	require.True(t, found)
+	require.Equal(t, peer1Access, access)
+
+	// peer2 should be found with peerStatusTemporary.
+	access, found = a.hasPeer(ctx, peer2)
+	require.True(t, found)
+	require.Equal(t, peer2Access, access)
+
+	// peer3 should be found with peerStatusRestricted.
+	access, found = a.hasPeer(ctx, peer3)
+	require.True(t, found)
+	require.Equal(t, peer3Access, access)
+
+	// peer4 should be found with peerStatusTemporary.
+	access, found = a.hasPeer(ctx, peer4)
+	require.True(t, found)
+	require.Equal(t, peer4Access, access)
+
+	// peer5 should NOT be found.
+	access, found = a.hasPeer(ctx, peer5)
+	require.False(t, found)
+	require.Equal(t, peerStatusRestricted, access)
+}
+
+// TestAddPeerAccessInbound asserts the num of slots is correctly incremented
+// only for a new inbound peer with restricted access.
+func TestAddPeerAccessInbound(t *testing.T) {
+	t.Parallel()
+
+	// Create a testing accessMan.
+	a := &accessMan{
+		peerChanInfo: make(map[string]channeldb.ChanCount),
+		peerScores:   make(map[string]peerSlotStatus),
+	}
+
+	// Create a testing key.
+	priv, err := btcec.NewPrivateKey()
+	require.NoError(t, err)
+	pub := priv.PubKey()
+	pubStr := string(pub.SerializeCompressed())
+
+	// Add this peer as an inbound peer with peerStatusRestricted.
+	a.addPeerAccess(pub, peerStatusRestricted, true)
+
+	// Assert the accessMan's internal state.
+	//
+	// We expect to see one peer found in the score map, and one slot is
+	// taken, and this peer is not found in the counts map.
+	require.Len(t, a.peerScores, 1)
+	require.Equal(t, int64(1), a.numRestricted)
+	require.NotContains(t, a.peerChanInfo, pubStr)
+
+	// The peer should be found in the score map.
+	score, ok := a.peerScores[pubStr]
+	require.True(t, ok)
+
+	expecedScore := peerSlotStatus{state: peerStatusRestricted}
+	require.Equal(t, expecedScore, score)
+
+	// Add this peer again, we expect the available slots to stay unchanged.
+	a.addPeerAccess(pub, peerStatusRestricted, true)
+
+	// Assert the internal state is not changed.
+	require.Len(t, a.peerScores, 1)
+	require.Equal(t, int64(1), a.numRestricted)
+	require.NotContains(t, a.peerChanInfo, pubStr)
+
+	// Reset the accessMan.
+	a = &accessMan{
+		peerChanInfo: make(map[string]channeldb.ChanCount),
+		peerScores:   make(map[string]peerSlotStatus),
+	}
+
+	// Add this peer as an inbound peer with peerStatusTemporary.
+	a.addPeerAccess(pub, peerStatusTemporary, true)
+
+	// Assert the accessMan's internal state.
+	//
+	// We expect to see one peer found in the score map, and no slot is
+	// taken since this peer is not restricted.
+	require.Len(t, a.peerScores, 1)
+	require.Equal(t, int64(0), a.numRestricted)
+
+	// NOTE: in reality this is not possible as the peer must have been put
+	// into the map `peerChanInfo` before its perm can be upgraded.
+	require.NotContains(t, a.peerChanInfo, pubStr)
+
+	// The peer should be found in the score map.
+	score, ok = a.peerScores[pubStr]
+	require.True(t, ok)
+
+	expecedScore = peerSlotStatus{state: peerStatusTemporary}
+	require.Equal(t, expecedScore, score)
+}
+
+// TestAddPeerAccessOutbound asserts that outbound peer is not restricted and
+// its perm is upgraded when it has peerStatusRestricted.
+func TestAddPeerAccessOutbound(t *testing.T) {
+	t.Parallel()
+
+	// Create a testing accessMan.
+	a := &accessMan{
+		peerChanInfo: make(map[string]channeldb.ChanCount),
+		peerScores:   make(map[string]peerSlotStatus),
+	}
+
+	// Create a testing key.
+	priv, err := btcec.NewPrivateKey()
+	require.NoError(t, err)
+	pub := priv.PubKey()
+	pubStr := string(pub.SerializeCompressed())
+
+	// Add this peer as an outbound peer with peerStatusRestricted.
+	a.addPeerAccess(pub, peerStatusRestricted, false)
+
+	// Assert the accessMan's internal state.
+	//
+	// We expect to see one peer found in the score map, and no slot is
+	// taken, and this peer is found in the counts map.
+	require.Len(t, a.peerScores, 1)
+	require.Equal(t, int64(0), a.numRestricted)
+	require.Contains(t, a.peerChanInfo, pubStr)
+
+	// The peer should be found in the score map.
+	score, ok := a.peerScores[pubStr]
+	require.True(t, ok)
+
+	// Its perm should be upgraded to temporary.
+	expecedScore := peerSlotStatus{state: peerStatusTemporary}
+	require.Equal(t, expecedScore, score)
+
+	// The peer should be found in the peer counts map.
+	count, ok := a.peerChanInfo[pubStr]
+	require.True(t, ok)
+
+	// The peer's count should be initialized correctly.
+	require.Zero(t, count.PendingOpenCount)
+	require.False(t, count.HasOpenOrClosedChan)
+
+	// Add this peer again, we expect the available slots to stay unchanged.
+	a.addPeerAccess(pub, peerStatusRestricted, true)
+
+	// Assert the internal state is not changed.
+	require.Len(t, a.peerScores, 1)
+	require.Equal(t, int64(0), a.numRestricted)
+	require.Contains(t, a.peerChanInfo, pubStr)
+
+	// Reset the accessMan.
+	a = &accessMan{
+		peerChanInfo: make(map[string]channeldb.ChanCount),
+		peerScores:   make(map[string]peerSlotStatus),
+	}
+
+	// Add this peer as an inbound peer with peerStatusTemporary.
+	a.addPeerAccess(pub, peerStatusTemporary, true)
+
+	// Assert the accessMan's internal state.
+	//
+	// We expect to see one peer found in the score map, and no slot is
+	// taken since this peer is not restricted.
+	require.Len(t, a.peerScores, 1)
+	require.Equal(t, int64(0), a.numRestricted)
+
+	// NOTE: in reality this is not possible as the peer must have been put
+	// into the map `peerChanInfo` before its perm can be upgraded.
+	require.NotContains(t, a.peerChanInfo, pubStr)
+
+	// The peer should be found in the score map.
+	score, ok = a.peerScores[pubStr]
+	require.True(t, ok)
+
+	expecedScore = peerSlotStatus{state: peerStatusTemporary}
+	require.Equal(t, expecedScore, score)
+}
+
+// TestRemovePeerAccess asserts `removePeerAccess` correctly update the
+// accessman's internal state based on the peer's status.
+func TestRemovePeerAccess(t *testing.T) {
+	t.Parallel()
+
+	// Create a testing accessMan.
+	a := &accessMan{
+		peerChanInfo: make(map[string]channeldb.ChanCount),
+		peerScores:   make(map[string]peerSlotStatus),
+	}
+
+	// numRestrictedExpected specifies the final value to expect once the
+	// test finishes.
+	var numRestrictedExpected int
+
+	// peer1 exists with an open channel, which should not be removed. Since
+	// it has protected status, the numRestricted should stay unchanged.
+	peer1 := "peer1"
+	a.peerChanInfo[peer1] = channeldb.ChanCount{
+		HasOpenOrClosedChan: true,
+	}
+	peer1Access := peerStatusProtected
+	a.peerScores[peer1] = peerSlotStatus{state: peer1Access}
+
+	// peer2 exists with a pending channel, which should not be removed.
+	// Since it has temporary status, the numRestricted should stay
+	// unchanged.
+	peer2 := "peer2"
+	a.peerChanInfo[peer2] = channeldb.ChanCount{
+		PendingOpenCount: 1,
+	}
+	peer2Access := peerStatusTemporary
+	a.peerScores[peer2] = peerSlotStatus{state: peer2Access}
+
+	// peer3 exists without any channels, which will be removed. Since it
+	// has restricted status, the numRestricted should be decremented.
+	peer3 := "peer3"
+	a.peerChanInfo[peer3] = channeldb.ChanCount{}
+	peer3Access := peerStatusRestricted
+	a.peerScores[peer3] = peerSlotStatus{state: peer3Access}
+	numRestrictedExpected--
+
+	// peer4 exists with a score and a temporary status, which will be
+	// removed.
+	peer4 := "peer4"
+	peer4Access := peerStatusTemporary
+	a.peerScores[peer4] = peerSlotStatus{state: peer4Access}
+
+	// peer5 doesn't exist, removing it will be a NOOP.
+	peer5 := "peer5"
+
+	// We now assert `removePeerAccess` behaves as expected.
+	//
+	// Remove peer1 should change nothing.
+	a.removePeerAccess(peer1)
+
+	// peer1 should be removed from peerScores but not peerChanInfo.
+	_, found := a.peerScores[peer1]
+	require.False(t, found)
+	_, found = a.peerChanInfo[peer1]
+	require.True(t, found)
+
+	// Remove peer2 should change nothing.
+	a.removePeerAccess(peer2)
+
+	// peer2 should be removed from peerScores but not peerChanInfo.
+	_, found = a.peerScores[peer2]
+	require.False(t, found)
+	_, found = a.peerChanInfo[peer2]
+	require.True(t, found)
+
+	// Remove peer3 should remove it from the maps.
+	a.removePeerAccess(peer3)
+
+	// peer3 should be removed from peerScores and peerChanInfo.
+	_, found = a.peerScores[peer3]
+	require.False(t, found)
+	_, found = a.peerChanInfo[peer3]
+	require.False(t, found)
+
+	// Remove peer4 should remove it from the maps.
+	a.removePeerAccess(peer4)
+
+	// peer4 should be removed from peerScores and NOT be found in
+	// peerChanInfo.
+	_, found = a.peerScores[peer4]
+	require.False(t, found)
+	_, found = a.peerChanInfo[peer4]
+	require.False(t, found)
+
+	// Remove peer5 should be NOOP.
+	a.removePeerAccess(peer5)
+
+	// peer5 should NOT be found.
+	_, found = a.peerScores[peer5]
+	require.False(t, found)
+	_, found = a.peerChanInfo[peer5]
+	require.False(t, found)
+
+	// Finally, assert the numRestricted is decremented as expected. Given
+	// we only have peer3 which has restricted access, it should decrement
+	// once.
+	//
+	// NOTE: The value is actually negative here, which is allowed in
+	// accessman.
+	require.EqualValues(t, numRestrictedExpected, a.numRestricted)
+}

channeldb/db.go

@@ -743,7 +743,7 @@ type ChanCount struct {
 func (c *ChannelStateDB) FetchPermAndTempPeers(
 	chainHash []byte) (map[string]ChanCount, error) {
 
-	peerCounts := make(map[string]ChanCount)
+	peerChanInfo := make(map[string]ChanCount)
 
 	err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
 		openChanBucket := tx.ReadBucket(openChannelBucket)
@@ -829,7 +829,7 @@ func (c *ChannelStateDB) FetchPermAndTempPeers(
 				HasOpenOrClosedChan: isPermPeer,
 				PendingOpenCount:    pendingOpenCount,
 			}
-			peerCounts[string(nodePub)] = peerCount
+			peerChanInfo[string(nodePub)] = peerCount
 
 			return nil
 		})
@@ -893,15 +893,15 @@ func (c *ChannelStateDB) FetchPermAndTempPeers(
 				remoteSer := remotePub.SerializeCompressed()
 				remoteKey := string(remoteSer)
 
-				count, exists := peerCounts[remoteKey]
+				count, exists := peerChanInfo[remoteKey]
 				if exists {
 					count.HasOpenOrClosedChan = true
-					peerCounts[remoteKey] = count
+					peerChanInfo[remoteKey] = count
 				} else {
 					peerCount := ChanCount{
 						HasOpenOrClosedChan: true,
 					}
-					peerCounts[remoteKey] = peerCount
+					peerChanInfo[remoteKey] = peerCount
 				}
 			}
 
@@ -913,10 +913,10 @@ func (c *ChannelStateDB) FetchPermAndTempPeers(
 
 		return nil
 	}, func() {
-		clear(peerCounts)
+		clear(peerChanInfo)
 	})
 
-	return peerCounts, err
+	return peerChanInfo, err
 }
 
 // channelSelector describes a function that takes a chain-hash bucket from

channeldb/db_test.go

@@ -770,16 +770,16 @@ func TestFetchPermTempPeer(t *testing.T) {
 	)
 
 	// Fetch the ChanCount for our peers.
-	peerCounts, err := cdb.FetchPermAndTempPeers(key[:])
+	peerChanInfo, err := cdb.FetchPermAndTempPeers(key[:])
 	require.NoError(t, err, "unable to fetch perm and temp peers")
 
 	// There should only be three entries.
-	require.Len(t, peerCounts, 3)
+	require.Len(t, peerChanInfo, 3)
 
 	// The first entry should have OpenClosed set to true and Pending set
 	// to 0.
-	count1, found := peerCounts[string(pubKey1.SerializeCompressed())]
-	require.True(t, found, "unable to find peer 1 in peerCounts")
+	count1, found := peerChanInfo[string(pubKey1.SerializeCompressed())]
+	require.True(t, found, "unable to find peer 1 in peerChanInfo")
 	require.True(
 		t, count1.HasOpenOrClosedChan,
 		"couldn't find peer 1's channels",
@@ -789,15 +789,15 @@ func TestFetchPermTempPeer(t *testing.T) {
 		"peer 1 doesn't have 0 pending-open",
 	)
 
-	count2, found := peerCounts[string(pubKey2.SerializeCompressed())]
-	require.True(t, found, "unable to find peer 2 in peerCounts")
+	count2, found := peerChanInfo[string(pubKey2.SerializeCompressed())]
+	require.True(t, found, "unable to find peer 2 in peerChanInfo")
 	require.False(
 		t, count2.HasOpenOrClosedChan, "found erroneous channels",
 	)
 	require.Equal(t, uint64(1), count2.PendingOpenCount)
 
-	count3, found := peerCounts[string(pubKey3.SerializeCompressed())]
-	require.True(t, found, "unable to find peer 3 in peerCounts")
+	count3, found := peerChanInfo[string(pubKey3.SerializeCompressed())]
+	require.True(t, found, "unable to find peer 3 in peerChanInfo")
 	require.True(
 		t, count3.HasOpenOrClosedChan,
 		"couldn't find peer 3's channels",

config.go

@@ -238,8 +238,9 @@ const (
 	// defaultHTTPHeaderTimeout is the default timeout for HTTP requests.
 	DefaultHTTPHeaderTimeout = 5 * time.Second
 
-	// DefaultNumRestrictedSlots is the default number of restricted slots
-	// we'll allocate in the server.
+	// DefaultNumRestrictedSlots is the default max number of incoming
+	// connections allowed in the server. Outbound connections are not
+	// restricted.
 	DefaultNumRestrictedSlots = 100
 
 	// BitcoinChainName is a string that represents the Bitcoin blockchain.
@@ -529,9 +530,9 @@ type Config struct {
 	// before timing out reading the headers of an HTTP request.
 	HTTPHeaderTimeout time.Duration `long:"http-header-timeout" description:"The maximum duration that the server will wait before timing out reading the headers of an HTTP request."`
 
-	// NumRestrictedSlots is the number of restricted slots we'll allocate
-	// in the server.
-	NumRestrictedSlots uint64 `long:"num-restricted-slots" description:"The number of restricted slots we'll allocate in the server."`
+	// NumRestrictedSlots is the max number of incoming connections allowed
+	// in the server. Outbound connections are not restricted.
+	NumRestrictedSlots uint64 `long:"num-restricted-slots" description:"The max number of incoming connections allowed in the server. Outbound connections are not restricted."`
 
 	// NoDisconnectOnPongFailure controls if we'll disconnect if a peer
 	// doesn't respond to a pong in time.

docs/release-notes/release-notes-0.19.2.md

@@ -41,6 +41,10 @@
 
 ## Functional Updates
 
+- [Improved](https://github.com/lightningnetwork/lnd/pull/9880) the connection
+  restriction logic enforced by `accessman`. In addition, the restriction placed
+  on outbound connections is now lifted.
+
 ## RPC Updates
 
 ## lncli Updates
@@ -71,5 +75,4 @@ much more slowly.
 ## Tooling and Documentation
 
 # Contributors (Alphabetical Order)
-
 * Yong Yu

funding/manager.go

@@ -511,7 +511,7 @@ type Config struct {
 
 	// NotifyOpenChannelEvent informs the ChannelNotifier when channels
 	// transition from pending open to open.
-	NotifyOpenChannelEvent func(wire.OutPoint, *btcec.PublicKey) error
+	NotifyOpenChannelEvent func(wire.OutPoint, *btcec.PublicKey)
 
 	// OpenChannelPredicate is a predicate on the lnwire.OpenChannel message
 	// and on the requesting node's public key that returns a bool which
@@ -521,13 +521,13 @@ type Config struct {
 	// NotifyPendingOpenChannelEvent informs the ChannelNotifier when
 	// channels enter a pending state.
 	NotifyPendingOpenChannelEvent func(wire.OutPoint,
-		*channeldb.OpenChannel, *btcec.PublicKey) error
+		*channeldb.OpenChannel, *btcec.PublicKey)
 
 	// NotifyFundingTimeout informs the ChannelNotifier when a pending-open
 	// channel times out because the funding transaction hasn't confirmed.
 	// This is only called for the fundee and only if the channel is
 	// zero-conf.
-	NotifyFundingTimeout func(wire.OutPoint, *btcec.PublicKey) error
+	NotifyFundingTimeout func(wire.OutPoint, *btcec.PublicKey)
 
 	// EnableUpfrontShutdown specifies whether the upfront shutdown script
 	// is enabled.
@@ -1319,13 +1319,9 @@ func (f *Manager) advancePendingChannelState(channel *channeldb.OpenChannel,
 
 		// Inform the ChannelNotifier that the channel has transitioned
 		// from pending open to open.
-		if err := f.cfg.NotifyOpenChannelEvent(
+		f.cfg.NotifyOpenChannelEvent(
 			channel.FundingOutpoint, channel.IdentityPub,
-		); err != nil {
-			log.Errorf("Unable to notify open channel event for "+
-				"ChannelPoint(%v): %v",
-				channel.FundingOutpoint, err)
-		}
+		)
 
 		// Find and close the discoverySignal for this channel such
 		// that ChannelReady messages will be processed.
@@ -2666,12 +2662,9 @@ func (f *Manager) fundeeProcessFundingCreated(peer lnpeer.Peer,
 
 	// Inform the ChannelNotifier that the channel has entered
 	// pending open state.
-	if err := f.cfg.NotifyPendingOpenChannelEvent(
+	f.cfg.NotifyPendingOpenChannelEvent(
 		fundingOut, completeChan, completeChan.IdentityPub,
-	); err != nil {
-		log.Errorf("Unable to send pending-open channel event for "+
-			"ChannelPoint(%v) %v", fundingOut, err)
-	}
+	)
 
 	// At this point we have sent our last funding message to the
 	// initiating peer before the funding transaction will be broadcast.
@@ -2891,13 +2884,9 @@ func (f *Manager) funderProcessFundingSigned(peer lnpeer.Peer,
 	case resCtx.updates <- upd:
 		// Inform the ChannelNotifier that the channel has entered
 		// pending open state.
-		if err := f.cfg.NotifyPendingOpenChannelEvent(
+		f.cfg.NotifyPendingOpenChannelEvent(
 			*fundingPoint, completeChan, completeChan.IdentityPub,
-		); err != nil {
-			log.Errorf("Unable to send pending-open channel "+
-				"event for ChannelPoint(%v) %v", fundingPoint,
-				err)
-		}
+		)
 
 	case <-f.quit:
 		return
@@ -2955,11 +2944,7 @@ func (f *Manager) fundingTimeout(c *channeldb.OpenChannel,
 	}
 
 	// Notify other subsystems about the funding timeout.
-	err := f.cfg.NotifyFundingTimeout(c.FundingOutpoint, c.IdentityPub)
-	if err != nil {
-		log.Errorf("failed to notify of funding timeout for "+
-			"ChanPoint(%v): %v", c.FundingOutpoint, err)
-	}
+	f.cfg.NotifyFundingTimeout(c.FundingOutpoint, c.IdentityPub)
 
 	timeoutErr := fmt.Errorf("timeout waiting for funding tx (%v) to "+
 		"confirm", c.FundingOutpoint)
@@ -3341,13 +3326,9 @@ func (f *Manager) handleFundingConfirmation(
 
 	// Inform the ChannelNotifier that the channel has transitioned from
 	// pending open to open.
-	if err := f.cfg.NotifyOpenChannelEvent(
+	f.cfg.NotifyOpenChannelEvent(
 		completeChan.FundingOutpoint, completeChan.IdentityPub,
-	); err != nil {
-		log.Errorf("Unable to notify open channel event for "+
-			"ChannelPoint(%v): %v", completeChan.FundingOutpoint,
-			err)
-	}
+	)
 
 	// Close the discoverySignal channel, indicating to a separate
 	// goroutine that the channel now is marked as open in the database

funding/manager_test.go

@@ -232,29 +232,23 @@ type mockChanEvent struct {
 }
 
 func (m *mockChanEvent) NotifyOpenChannelEvent(outpoint wire.OutPoint,
-	remotePub *btcec.PublicKey) error {
+	remotePub *btcec.PublicKey) {
 
 	m.openEvent <- outpoint
-
-	return nil
 }
 
 func (m *mockChanEvent) NotifyPendingOpenChannelEvent(outpoint wire.OutPoint,
 	pendingChannel *channeldb.OpenChannel,
-	remotePub *btcec.PublicKey) error {
+	remotePub *btcec.PublicKey) {
 
 	m.pendingOpenEvent <- channelnotifier.PendingOpenChannelEvent{
 		ChannelPoint:   &outpoint,
 		PendingChannel: pendingChannel,
 	}
-
-	return nil
 }
 
 func (m *mockChanEvent) NotifyFundingTimeout(outpoint wire.OutPoint,
-	remotePub *btcec.PublicKey) error {
-
-	return nil
+	remotePub *btcec.PublicKey) {
 }
 
 // mockZeroConfAcceptor always accepts the channel open request for zero-conf

itest/list_on_test.go

@@ -691,10 +691,6 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "funding manager funding timeout",
 		TestFunc: testFundingManagerFundingTimeout,
 	},
-	{
-		Name:     "access perm",
-		TestFunc: testAccessPerm,
-	},
 	{
 		Name:     "rbf coop close",
 		TestFunc: testCoopCloseRbf,
@@ -782,6 +778,9 @@ func init() {
 		"coop close with external delivery", allTestCases,
 		coopCloseWithExternalTestCases,
 	)
+	allTestCases = appendPrefixed(
+		"peer conn", allTestCases, peerConnTestCases,
+	)
 
 	// Prepare the test cases for windows to exclude some of the flaky
 	// ones.

itest/lnd_access_perm_test.go

@@ -1,93 +1,341 @@
 package itest
 
 import (
-	"strconv"
-
-	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lntest"
+	"github.com/stretchr/testify/require"
 )
 
-// testAccessPerm tests that the number of restricted slots is upheld when
-// connecting to the server from a restrictedd peer.
-func testAccessPerm(ht *lntest.HarnessTest) {
-	args := []string{
-		"--minbackoff=5m",
-		"--maxbackoff=5m",
-		"--num-restricted-slots=5",
-	}
+var peerConnTestCases = []*lntest.TestCase{
+	{
+		Name:     "restricted on inbound",
+		TestFunc: testPeerConnRestrictedOnInbound,
+	},
+	{
+		Name:     "already connected",
+		TestFunc: testPeerConnAlreadyConnected,
+	},
+	{
+		Name:     "unlimited outbound",
+		TestFunc: testPeerConnUnlimitedOutbound,
+	},
+	{
+		Name:     "upgrade access perm",
+		TestFunc: testPeerConnUpgradeAccessPerm,
+	},
+	{
+		Name:     "node restart",
+		TestFunc: testPeerConnNodeRestart,
+	},
+	{
+		Name:     "peer reconnect",
+		TestFunc: testPeerConnPeerReconnect,
+	},
+}
 
-	alice := ht.NewNodeWithCoins("Alice", args)
-	bob := ht.NewNodeWithCoins("Bob", args)
-	ht.ConnectNodes(alice, bob)
+// testPeerConnRestrictedOnInbound checks that when the `num-restricted-slots`
+// is reached, no more inbound connection is allowed. In addition, when a slot
+// becomes available, new inbound connection should be allowed.
+func testPeerConnRestrictedOnInbound(ht *lntest.HarnessTest) {
+	args := []string{"--num-restricted-slots=1"}
 
-	// Open a confirmed channel to Bob. Bob will have protected access.
-	chanPoint1 := ht.OpenChannel(
-		alice, bob, lntest.OpenChannelParams{
-			Amt: chanAmt,
-		},
-	)
-	defer ht.CloseChannel(alice, chanPoint1)
+	// Create a new node with only one slot available.
+	alice := ht.NewNode("Alice", args)
 
-	// Open and close channel to Carol. Carol will have protected access.
-	carol := ht.NewNodeWithCoins("Carol", args)
-	ht.ConnectNodes(alice, carol)
+	// Create two nodes Bob and Carol. Bob will connect to Alice first,
+	// taking up Alice's only slot, and we expect the connection from Carol
+	// to Alice to be failed.
+	bob := ht.NewNode("Bob", nil)
+	carol := ht.NewNode("Carol", nil)
 
-	chanPoint2 := ht.OpenChannel(
-		alice, carol, lntest.OpenChannelParams{
-			Amt: chanAmt,
-		},
-	)
-
-	ht.CloseChannel(alice, chanPoint2)
-
-	// Make a pending channel with Dave.
-	dave := ht.NewNodeWithCoins("Dave", args)
-	ht.ConnectNodes(alice, dave)
-
-	ht.OpenChannelAssertStream(
-		dave, alice, lntest.OpenChannelParams{
-			Amt: chanAmt,
-		},
-	)
-
-	// Disconnect Bob, Carol, and Dave.
-	ht.DisconnectNodes(alice, bob)
-	ht.AssertNotConnected(alice, bob)
-
-	ht.DisconnectNodes(alice, carol)
-	ht.AssertNotConnected(alice, carol)
-
-	ht.DisconnectNodes(alice, dave)
-	ht.AssertNotConnected(alice, dave)
-
-	// Connect 5 times to Alice. All of these connections should be
-	// successful.
-	for i := 0; i < 5; i++ {
-		peer := ht.NewNode("Peer"+strconv.Itoa(i), args)
-		ht.ConnectNodes(peer, alice)
-		ht.AssertConnected(peer, alice)
-	}
-
-	// Connect an additional time to Alice. This should fail.
-	failedPeer := ht.NewNode("FailedPeer", args)
-	req := &lnrpc.ConnectPeerRequest{
-		Addr: &lnrpc.LightningAddress{
-			Pubkey: alice.RPC.GetInfo().IdentityPubkey,
-			Host:   alice.Cfg.P2PAddr(),
-		},
-	}
-	_ = failedPeer.RPC.ConnectPeer(req)
-	ht.AssertNotConnected(failedPeer, alice)
-
-	// Connect nodes and assert access status.
-	ht.ConnectNodes(alice, bob)
+	// Bob now connects to Alice - from Alice's PoV, this is her inbound
+	// connection from Bob. We expect Bob to connect to Alice successfully.
+	_, err := ht.ConnectNodesNoAssert(bob, alice)
+	require.NoError(ht, err)
 	ht.AssertConnected(alice, bob)
 
-	ht.ConnectNodes(alice, carol)
+	// Carol now connects to Alice - from Alice's PoV, this is her inbound
+	// connection from Carol. Carol's connection should be failed.
+	_, err = ht.ConnectNodesNoAssert(carol, alice)
+	require.NoError(ht, err)
+	ht.AssertNotConnected(alice, carol)
+
+	// Bob now disconnects, which will free up Alice's slot.
+	ht.DisconnectNodes(bob, alice)
+
+	// Carol connects again - since Alice's slot is freed, this connection
+	// should succeed.
+	_, err = ht.ConnectNodesNoAssert(carol, alice)
+	require.NoError(ht, err)
+
+	ht.AssertConnected(alice, carol)
+	ht.AssertNotConnected(alice, bob)
+}
+
+// testPeerConnAlreadyConnected checks that when there's already a connection
+// alive, another attempt to connect doesn't take up the slot or kill the
+// existing connection, in specific,
+//   - When Alice has an inbound connection from Bob, another inbound connection
+//     from Bob will be noop.
+//   - When Bob has an outbound connection to Alice, another outbound connection
+//     to Alice will be noop.
+//
+// In this test we will create nodes using the dev flag `unsafeconnect` to mimic
+// the behaviour of persistent/permanent peer connections, where it's likely
+// inbound and outbound connections are happening at the same time.
+func testPeerConnAlreadyConnected(ht *lntest.HarnessTest) {
+	args := []string{
+		"--num-restricted-slots=1",
+	}
+
+	// Create a new node with two slots available.
+	alice := ht.NewNode("Alice", args)
+	bob := ht.NewNode("Bob", []string{"--dev.unsafeconnect"})
+	carol := ht.NewNode("Carol", nil)
+
+	// Bob now connects to Alice - from Alice's PoV, this is her inbound
+	// connection from Bob. We expect Bob to connect to Alice successfully.
+	_, err := ht.ConnectNodesNoAssert(bob, alice)
+	require.NoError(ht, err)
+	ht.AssertConnected(alice, bob)
+
+	// Assert Alice's slot has been filled up by connecting Carol to Alice.
+	_, err = ht.ConnectNodesNoAssert(carol, alice)
+	require.NoError(ht, err)
+	ht.AssertNotConnected(alice, carol)
+
+	// Bob connects to Alice again - from Alice's PoV, she already has an
+	// inbound connection from Bob so this connection attempt should be
+	// noop. We expect Alice and Bob to stay connected.
+	//
+	// TODO(yy): There's no way to assert the connection stays the same atm,
+	// need to update the RPC to return the socket port. As for now we need
+	// to visit the logs to check the connection is the same or not.
+	_, err = ht.ConnectNodesNoAssert(bob, alice)
+	require.NoError(ht, err)
+	ht.AssertConnected(alice, bob)
+}
+
+// testPeerConnUnlimitedOutbound checks that for outbound connections, they are
+// not restricted by the `num-restricted-slots` config.
+func testPeerConnUnlimitedOutbound(ht *lntest.HarnessTest) {
+	args := []string{"--num-restricted-slots=1"}
+
+	// Create a new node with one slot available.
+	alice := ht.NewNode("Alice", args)
+
+	// Create three nodes. Alice will have an inbound connection with Bob
+	// and outbound connections with Carol and Dave.
+	bob := ht.NewNode("Bob", args)
+	carol := ht.NewNode("Carol", args)
+	dave := ht.NewNode("Dave", args)
+
+	// Bob now connects to Alice - from Alice's PoV, this is her inbound
+	// connection from Bob. We expect Bob to connect to Alice successfully.
+	_, err := ht.ConnectNodesNoAssert(bob, alice)
+	require.NoError(ht, err)
+	ht.AssertConnected(alice, bob)
+
+	// Assert Alice's slot has been filled up by connecting Carol to Alice.
+	_, err = ht.ConnectNodesNoAssert(carol, alice)
+	require.NoError(ht, err)
+	ht.AssertNotConnected(alice, carol)
+
+	// Now let Alice make an outbound connection to Carol and assert it's
+	// succeeded.
+	_, err = ht.ConnectNodesNoAssert(alice, carol)
+	require.NoError(ht, err)
 	ht.AssertConnected(alice, carol)
 
-	ht.ConnectNodes(alice, dave)
+	// Alice can also make an outbound connection to Dave and assert it's
+	// succeeded since outbound connection is not restricted.
+	_, err = ht.ConnectNodesNoAssert(alice, dave)
+	require.NoError(ht, err)
 	ht.AssertConnected(alice, dave)
-
-	ht.MineBlocksAndAssertNumTxes(1, 1)
+}
+
+// testPeerConnUpgradeAccessPerm checks that when a peer has, or used to have a
+// channel with Alice, it won't use her restricted slots.
+func testPeerConnUpgradeAccessPerm(ht *lntest.HarnessTest) {
+	args := []string{"--num-restricted-slots=1"}
+
+	// Create a new node with one slot available.
+	alice := ht.NewNodeWithCoins("Alice", args)
+	bob := ht.NewNode("Bob", nil)
+	carol := ht.NewNodeWithCoins("Carol", nil)
+	dave := ht.NewNode("Dave", nil)
+	eve := ht.NewNode("Eve", nil)
+
+	// Connect Bob to Alice, which will use Alice's available slot.
+	ht.ConnectNodes(bob, alice)
+
+	// Assert Alice's slot has been filled up by connecting Carol to Alice.
+	_, err := ht.ConnectNodesNoAssert(carol, alice)
+	require.NoError(ht, err)
+	ht.AssertNotConnected(alice, carol)
+
+	// Open a channel from Alice to Bob and let it stay pending.
+	p := lntest.OpenChannelParams{
+		Amt: chanAmt,
+	}
+	pendingUpdate := ht.OpenChannelAssertPending(alice, bob, p)
+	cpAB := lntest.ChanPointFromPendingUpdate(pendingUpdate)
+
+	// Connect Carol to Alice - since Bob now has a pending channel with
+	// Alice, there's a slot available for Carol to connect.
+	ht.ConnectNodes(carol, alice)
+
+	// Open a channel from Carol to Alice and let it stay pending.
+	pendingUpdate = ht.OpenChannelAssertPending(carol, alice, p)
+	cpCA := lntest.ChanPointFromPendingUpdate(pendingUpdate)
+
+	// Mine the funding txns.
+	ht.MineBlocksAndAssertNumTxes(1, 2)
+
+	// Dave should be able to connect to Alice.
+	ht.ConnectNodes(dave, alice)
+
+	// Open a channel from Alice to Dave, which will free up Alice's slot.
+	cpAD := ht.OpenChannel(alice, dave, p)
+
+	// Close the channels.
+	ht.CloseChannel(bob, cpAB)
+	ht.CloseChannel(carol, cpCA)
+	ht.CloseChannel(dave, cpAD)
+
+	// Alice should have one slot available, connect Eve to Alice now.
+	ht.ConnectNodes(eve, alice)
+}
+
+// testPeerConnNodeRestart checks that when a peer has or used to have a channel
+// with Alice, when Alice restarts, she should still have the available slot for
+// more inbound connections.
+func testPeerConnNodeRestart(ht *lntest.HarnessTest) {
+	args := []string{"--num-restricted-slots=1"}
+
+	// Create a new node with one slot available.
+	alice := ht.NewNodeWithCoins("Alice", args)
+	bob := ht.NewNode("Bob", []string{"--dev.unsafeconnect"})
+	carol := ht.NewNode("Carol", nil)
+
+	// Connect Bob to Alice, which will use Alice's available slot.
+	ht.ConnectNodes(bob, alice)
+
+	// Assert Alice's slot has been filled up by connecting Carol to Alice.
+	_, err := ht.ConnectNodesNoAssert(carol, alice)
+	require.NoError(ht, err)
+	ht.AssertNotConnected(alice, carol)
+
+	// Restart Alice, which will reset her current slots, allowing Bob to
+	// connect to her again.
+	ht.RestartNode(alice)
+	ht.ConnectNodes(bob, alice)
+
+	// Open a channel from Alice to Bob and let it stay pending.
+	p := lntest.OpenChannelParams{
+		Amt: chanAmt,
+	}
+	pendingUpdate := ht.OpenChannelAssertPending(alice, bob, p)
+	cp := lntest.ChanPointFromPendingUpdate(pendingUpdate)
+
+	// Restart Alice and let Bob connect to her - since Bob has a pending
+	// channel, it shouldn't take any slot.
+	ht.RestartNode(alice)
+	ht.ConnectNodes(bob, alice)
+
+	// Connect Carol to Alice since Alice has a free slot.
+	ht.ConnectNodes(carol, alice)
+
+	// Mine the funding tx.
+	ht.MineBlocksAndAssertNumTxes(1, 1)
+
+	// Restart Alice and let Bob connect to her - since Bob has an open
+	// channel, it shouldn't take any slot.
+	ht.RestartNode(alice)
+	ht.ConnectNodes(bob, alice)
+
+	// Connect Carol to Alice since Alice has a free slot.
+	ht.ConnectNodes(carol, alice)
+
+	// Close the channel.
+	ht.CloseChannel(alice, cp)
+
+	// Restart Alice and let Bob connect to her - since Bob has a closed
+	// channel, it shouldn't take any slot.
+	ht.RestartNode(alice)
+	ht.ConnectNodes(bob, alice)
+
+	// Connect Carol to Alice since Alice has a free slot.
+	ht.ConnectNodes(carol, alice)
+}
+
+// testPeerConnPeerReconnect checks that when a peer has or used to have a
+// channel with Alice, it will not account for the restricted slot during
+// reconnection.
+func testPeerConnPeerReconnect(ht *lntest.HarnessTest) {
+	args := []string{"--num-restricted-slots=1"}
+
+	// Create a new node with one slot available.
+	alice := ht.NewNodeWithCoins("Alice", args)
+	bob := ht.NewNode("Bob", []string{"--dev.unsafeconnect"})
+	carol := ht.NewNode("Carol", nil)
+
+	// Connect Bob to Alice, which will use Alice's available slot.
+	ht.ConnectNodes(bob, alice)
+
+	// Let Bob connect to Alice again, which put Bob in Alice's
+	// `scheduledPeerConnection` map.
+	ht.ConnectNodes(bob, alice)
+
+	// Assert Alice's slot has been filled up by connecting Carol to Alice.
+	_, err := ht.ConnectNodesNoAssert(carol, alice)
+	require.NoError(ht, err)
+	ht.AssertNotConnected(alice, carol)
+
+	// Open a channel from Alice to Bob and let it stay pending.
+	p := lntest.OpenChannelParams{
+		Amt: chanAmt,
+	}
+	pendingUpdate := ht.OpenChannelAssertPending(alice, bob, p)
+	cp := lntest.ChanPointFromPendingUpdate(pendingUpdate)
+
+	// Bob now perform a reconnection - since Bob has a pending channel, it
+	// shouldn't take any slot.
+	ht.DisconnectNodes(bob, alice)
+	ht.AssertNotConnected(alice, bob)
+	ht.ConnectNodes(bob, alice)
+
+	// Connect Carol to Alice since Alice has a free slot.
+	ht.ConnectNodes(carol, alice)
+
+	// Once the above connection succeeded we let Carol disconnect to free
+	// the slot.
+	ht.DisconnectNodes(carol, alice)
+
+	// Mine the funding tx.
+	ht.MineBlocksAndAssertNumTxes(1, 1)
+
+	// Bob now perform a reconnection - since Bob has a pending channel, it
+	// shouldn't take any slot.
+	ht.DisconnectNodes(bob, alice)
+	ht.AssertNotConnected(alice, bob)
+	ht.ConnectNodes(bob, alice)
+
+	// Connect Carol to Alice since Alice has a free slot.
+	ht.ConnectNodes(carol, alice)
+
+	// Once the above connection succeeded we let Carol disconnect to free
+	// the slot.
+	ht.DisconnectNodes(carol, alice)
+
+	// Close the channel.
+	ht.CloseChannel(alice, cp)
+
+	// Bob now perform a reconnection - since Bob has a pending channel, it
+	// shouldn't take any slot.
+	ht.DisconnectNodes(bob, alice)
+	ht.AssertNotConnected(alice, bob)
+	ht.ConnectNodes(bob, alice)
+
+	// Connect Carol to Alice since Alice has a free slot.
+	ht.ConnectNodes(carol, alice)
 }

lncfg/dev.go

@@ -52,3 +52,9 @@ func (d *DevConfig) GetZombieSweeperInterval() time.Duration {
 func (d *DevConfig) GetMaxWaitNumBlocksFundingConf() uint32 {
 	return DefaultMaxWaitNumBlocksFundingConf
 }
+
+// GetUnsafeConnect returns the config value `UnsafeConnect`, which is always
+// false for production build.
+func (d *DevConfig) GetUnsafeConnect() bool {
+	return false
+}

lncfg/dev_integration.go

@@ -26,6 +26,7 @@ type DevConfig struct {
 	ZombieSweeperInterval       time.Duration `long:"zombiesweeperinterval" description:"The time interval at which channel opening flows are evaluated for zombie status."`
 	UnsafeDisconnect            bool          `long:"unsafedisconnect" description:"Allows the rpcserver to intentionally disconnect from peers with open channels."`
 	MaxWaitNumBlocksFundingConf uint32        `long:"maxwaitnumblocksfundingconf" description:"Maximum blocks to wait for funding confirmation before discarding non-initiated channels."`
+	UnsafeConnect               bool          `long:"unsafeconnect" description:"Allow the rpcserver to connect to a peer even if there's already a connection."`
 }
 
 // ChannelReadyWait returns the config value `ProcessChannelReadyWait`.
@@ -51,7 +52,7 @@ func (d *DevConfig) GetZombieSweeperInterval() time.Duration {
 	return d.ZombieSweeperInterval
 }
 
-// ChannelReadyWait returns the config value `UnsafeDisconnect`.
+// GetUnsafeDisconnect returns the config value `UnsafeDisconnect`.
 func (d *DevConfig) GetUnsafeDisconnect() bool {
 	return d.UnsafeDisconnect
 }
@@ -65,3 +66,8 @@ func (d *DevConfig) GetMaxWaitNumBlocksFundingConf() uint32 {
 
 	return d.MaxWaitNumBlocksFundingConf
 }
+
+// GetUnsafeConnect returns the config value `UnsafeConnect`.
+func (d *DevConfig) GetUnsafeConnect() bool {
+	return d.UnsafeConnect
+}

lntest/harness_assertion.go

@@ -119,7 +119,7 @@ func (h *HarnessTest) ConnectNodes(a, b *node.HarnessNode) {
 		},
 	}
 	a.RPC.ConnectPeer(req)
-	h.AssertPeerConnected(a, b)
+	h.AssertConnected(a, b)
 }
 
 // ConnectNodesPerm creates a persistent connection between the two nodes and
@@ -240,6 +240,24 @@ func (h *HarnessTest) EnsureConnected(a, b *node.HarnessNode) {
 	h.AssertPeerConnected(b, a)
 }
 
+// ConnectNodesNoAssert creates a connection from node A to node B.
+func (h *HarnessTest) ConnectNodesNoAssert(a, b *node.HarnessNode) (
+	*lnrpc.ConnectPeerResponse, error) {
+
+	bobInfo := b.RPC.GetInfo()
+
+	req := &lnrpc.ConnectPeerRequest{
+		Addr: &lnrpc.LightningAddress{
+			Pubkey: bobInfo.IdentityPubkey,
+			Host:   b.Cfg.P2PAddr(),
+		},
+	}
+	ctxt, cancel := context.WithTimeout(h.runCtx, DefaultTimeout)
+	defer cancel()
+
+	return a.RPC.LN.ConnectPeer(ctxt, req)
+}
+
 // AssertNumEdges checks that an expected number of edges can be found in the
 // node specified.
 func (h *HarnessTest) AssertNumEdges(hn *node.HarnessNode,
@@ -1669,6 +1687,11 @@ func (h *HarnessTest) AssertPeerNotConnected(a, b *node.HarnessNode) {
 
 // AssertNotConnected asserts that two peers are not connected.
 func (h *HarnessTest) AssertNotConnected(a, b *node.HarnessNode) {
+	// Sleep one second before the assertion to make sure that when there's
+	// a RPC call to connect, that RPC call is finished before the
+	// assertion.
+	time.Sleep(1 * time.Second)
+
 	h.AssertPeerNotConnected(a, b)
 	h.AssertPeerNotConnected(b, a)
 }

sample-lnd.conf

@@ -566,7 +566,8 @@
 ; the headers of an HTTP request.
 ; http-header-timeout=5s
 
-; The number of restricted slots the server will allocate for peers.
+; The max number of incoming connections allowed in the server. Outbound
+; connections are not restricted.
 ; num-restricted-slots=100
 
 ; If true, a peer will *not* be disconnected if a pong is not received in time

server.go

@@ -193,6 +193,23 @@ const (
 	peerStatusProtected
 )
 
+// String returns a human-readable representation of the status code.
+func (p peerAccessStatus) String() string {
+	switch p {
+	case peerStatusRestricted:
+		return "restricted"
+
+	case peerStatusTemporary:
+		return "temporary"
+
+	case peerStatusProtected:
+		return "protected"
+
+	default:
+		return "unknown"
+	}
+}
+
 // peerSlotStatus determines whether a peer gets access to one of our free
 // slots or gets to bypass this safety mechanism.
 type peerSlotStatus struct {
@@ -1891,7 +1908,9 @@ func newServer(ctx context.Context, cfg *Config, listenAddrs []net.Addr,
 		// connection requests when we call NewListener.
 		listeners[i], err = brontide.NewListener(
 			nodeKeyECDH, listenAddr.String(),
-			s.peerAccessMan.checkIncomingConnBanScore,
+			// TODO(yy): remove this check and unify the inbound
+			// connection check inside `InboundPeerConnected`.
+			s.peerAccessMan.checkAcceptIncomingConn,
 		)
 		if err != nil {
 			return nil, err
@@ -4009,22 +4028,6 @@ func (s *server) InboundPeerConnected(conn net.Conn) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	// If the remote node's public key is banned, drop the connection.
-	access, err := s.peerAccessMan.assignPeerPerms(nodePub)
-	if err != nil {
-		// Clean up the persistent peer maps if we're dropping this
-		// connection.
-		s.bannedPersistentPeerConnection(pubStr)
-
-		srvrLog.Debugf("Dropping connection for %x since we are out "+
-			"of restricted-access connection slots: %v.", pubSer,
-			err)
-
-		conn.Close()
-
-		return
-	}
-
 	// If we already have an outbound connection to this peer, then ignore
 	// this new connection.
 	if p, ok := s.outboundPeers[pubStr]; ok {
@@ -4059,7 +4062,7 @@ func (s *server) InboundPeerConnected(conn net.Conn) {
 		// We were unable to locate an existing connection with the
 		// target peer, proceed to connect.
 		s.cancelConnReqs(pubStr, nil)
-		s.peerConnected(conn, nil, true, access)
+		s.peerConnected(conn, nil, true)
 
 	case nil:
 		// We already have a connection with the incoming peer. If the
@@ -4091,7 +4094,7 @@ func (s *server) InboundPeerConnected(conn net.Conn) {
 		s.removePeer(connectedPeer)
 		s.ignorePeerTermination[connectedPeer] = struct{}{}
 		s.scheduledPeerConnection[pubStr] = func() {
-			s.peerConnected(conn, nil, true, access)
+			s.peerConnected(conn, nil, true)
 		}
 	}
 }
@@ -4116,25 +4119,6 @@ func (s *server) OutboundPeerConnected(connReq *connmgr.ConnReq, conn net.Conn)
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	access, err := s.peerAccessMan.assignPeerPerms(nodePub)
-	if err != nil {
-		// Clean up the persistent peer maps if we're dropping this
-		// connection.
-		s.bannedPersistentPeerConnection(pubStr)
-
-		srvrLog.Debugf("Dropping connection for %x since we are out "+
-			"of restricted-access connection slots: %v.", pubSer,
-			err)
-
-		if connReq != nil {
-			s.connMgr.Remove(connReq.ID())
-		}
-
-		conn.Close()
-
-		return
-	}
-
 	// If we already have an inbound connection to this peer, then ignore
 	// this new connection.
 	if p, ok := s.inboundPeers[pubStr]; ok {
@@ -4169,7 +4153,7 @@ func (s *server) OutboundPeerConnected(connReq *connmgr.ConnReq, conn net.Conn)
 		return
 	}
 
-	srvrLog.Infof("Established connection to: %x@%v", pubStr,
+	srvrLog.Infof("Established outbound connection to: %x@%v", pubStr,
 		conn.RemoteAddr())
 
 	if connReq != nil {
@@ -4193,7 +4177,7 @@ func (s *server) OutboundPeerConnected(connReq *connmgr.ConnReq, conn net.Conn)
 	case ErrPeerNotConnected:
 		// We were unable to locate an existing connection with the
 		// target peer, proceed to connect.
-		s.peerConnected(conn, connReq, false, access)
+		s.peerConnected(conn, connReq, false)
 
 	case nil:
 		// We already have a connection with the incoming peer. If the
@@ -4227,7 +4211,7 @@ func (s *server) OutboundPeerConnected(connReq *connmgr.ConnReq, conn net.Conn)
 		s.removePeer(connectedPeer)
 		s.ignorePeerTermination[connectedPeer] = struct{}{}
 		s.scheduledPeerConnection[pubStr] = func() {
-			s.peerConnected(conn, connReq, false, access)
+			s.peerConnected(conn, connReq, false)
 		}
 	}
 }
@@ -4304,43 +4288,48 @@ func (s *server) SubscribeCustomMessages() (*subscribe.Client, error) {
 // notifyOpenChannelPeerEvent updates the access manager's maps and then calls
 // the channelNotifier's NotifyOpenChannelEvent.
 func (s *server) notifyOpenChannelPeerEvent(op wire.OutPoint,
-	remotePub *btcec.PublicKey) error {
+	remotePub *btcec.PublicKey) {
 
 	// Call newOpenChan to update the access manager's maps for this peer.
 	if err := s.peerAccessMan.newOpenChan(remotePub); err != nil {
-		return err
+		srvrLog.Errorf("Failed to update peer[%x] access status after "+
+			"channel[%v] open", remotePub.SerializeCompressed(), op)
 	}
 
 	// Notify subscribers about this open channel event.
 	s.channelNotifier.NotifyOpenChannelEvent(op)
-
-	return nil
 }
 
 // notifyPendingOpenChannelPeerEvent updates the access manager's maps and then
 // calls the channelNotifier's NotifyPendingOpenChannelEvent.
 func (s *server) notifyPendingOpenChannelPeerEvent(op wire.OutPoint,
-	pendingChan *channeldb.OpenChannel, remotePub *btcec.PublicKey) error {
+	pendingChan *channeldb.OpenChannel, remotePub *btcec.PublicKey) {
 
 	// Call newPendingOpenChan to update the access manager's maps for this
 	// peer.
 	if err := s.peerAccessMan.newPendingOpenChan(remotePub); err != nil {
-		return err
+		srvrLog.Errorf("Failed to update peer[%x] access status after "+
+			"channel[%v] pending open",
+			remotePub.SerializeCompressed(), op)
 	}
 
 	// Notify subscribers about this event.
 	s.channelNotifier.NotifyPendingOpenChannelEvent(op, pendingChan)
-
-	return nil
 }
 
 // notifyFundingTimeoutPeerEvent updates the access manager's maps and then
 // calls the channelNotifier's NotifyFundingTimeout.
 func (s *server) notifyFundingTimeoutPeerEvent(op wire.OutPoint,
-	remotePub *btcec.PublicKey) error {
+	remotePub *btcec.PublicKey) {
 
 	// Call newPendingCloseChan to potentially demote the peer.
 	err := s.peerAccessMan.newPendingCloseChan(remotePub)
+	if err != nil {
+		srvrLog.Errorf("Failed to update peer[%x] access status after "+
+			"channel[%v] pending close",
+			remotePub.SerializeCompressed(), op)
+	}
+
 	if errors.Is(err, ErrNoMoreRestrictedAccessSlots) {
 		// If we encounter an error while attempting to disconnect the
 		// peer, log the error.
@@ -4351,8 +4340,6 @@ func (s *server) notifyFundingTimeoutPeerEvent(op wire.OutPoint,
 
 	// Notify subscribers about this event.
 	s.channelNotifier.NotifyFundingTimeout(op)
-
-	return nil
 }
 
 // peerConnected is a function that handles initialization a newly connected
@@ -4360,12 +4347,35 @@ func (s *server) notifyFundingTimeoutPeerEvent(op wire.OutPoint,
 // starting all the goroutines the peer needs to function properly. The inbound
 // boolean should be true if the peer initiated the connection to us.
 func (s *server) peerConnected(conn net.Conn, connReq *connmgr.ConnReq,
-	inbound bool, access peerAccessStatus) {
+	inbound bool) {
 
 	brontideConn := conn.(*brontide.Conn)
 	addr := conn.RemoteAddr()
 	pubKey := brontideConn.RemotePub()
 
+	// Only restrict access for inbound connections, which means if the
+	// remote node's public key is banned or the restricted slots are used
+	// up, we will drop the connection.
+	//
+	// TODO(yy): Consider perform this check in
+	// `peerAccessMan.addPeerAccess`.
+	access, err := s.peerAccessMan.assignPeerPerms(pubKey)
+	if inbound && err != nil {
+		pubSer := pubKey.SerializeCompressed()
+
+		// Clean up the persistent peer maps if we're dropping this
+		// connection.
+		s.bannedPersistentPeerConnection(string(pubSer))
+
+		srvrLog.Debugf("Dropping connection for %x since we are out "+
+			"of restricted-access connection slots: %v.", pubSer,
+			err)
+
+		conn.Close()
+
+		return
+	}
+
 	srvrLog.Infof("Finalizing connection to %x@%s, inbound=%v",
 		pubKey.SerializeCompressed(), addr, inbound)
 
@@ -4503,7 +4513,7 @@ func (s *server) peerConnected(conn net.Conn, connReq *connmgr.ConnReq,
 	p := peer.NewBrontide(pCfg)
 
 	// Update the access manager with the access permission for this peer.
-	s.peerAccessMan.addPeerAccess(pubKey, access)
+	s.peerAccessMan.addPeerAccess(pubKey, access, inbound)
 
 	// TODO(roasbeef): update IP address for link-node
 	//  * also mark last-seen, do it one single transaction?
@@ -4965,7 +4975,8 @@ func (s *server) removePeer(p *peer.Brontide) {
 	}
 
 	// Remove the peer's access permission from the access manager.
-	s.peerAccessMan.removePeerAccess(p.IdentityKey())
+	peerPubStr := string(p.IdentityKey().SerializeCompressed())
+	s.peerAccessMan.removePeerAccess(peerPubStr)
 
 	// Copy the peer's error buffer across to the server if it has any items
 	// in it so that we can restore peer errors across connections.
@@ -4999,7 +5010,11 @@ func (s *server) ConnectToPeer(addr *lnwire.NetAddress,
 
 	// Ensure we're not already connected to this peer.
 	peer, err := s.findPeerByPubStr(targetPub)
-	if err == nil {
+
+	// When there's no error it means we already have a connection with this
+	// peer. If this is a dev environment with the `--unsafeconnect` flag
+	// set, we will ignore the existing connection and continue.
+	if err == nil && !s.cfg.Dev.GetUnsafeConnect() {
 		s.mu.Unlock()
 		return &errPeerAlreadyConnected{peer: peer}
 	}