Merge pull request #8509 from GeorgeTsagk/scid-alias-rpcs

Add more RPCs for scid aliases

Author: guggero

aliasmgr/aliasmgr.go

@@ -10,6 +10,11 @@ import (
 	"github.com/lightningnetwork/lnd/lnwire"
 )
 
+// UpdateLinkAliases locates the active link that matches the given
+// shortID and triggers an update based on the latest values of the
+// alias manager.
+type UpdateLinkAliases func(shortID lnwire.ShortChannelID) error
+
 var (
 	// aliasBucket stores aliases as keys and their base SCIDs as values.
 	// This is used to populate the maps that the Manager uses. The keys
@@ -77,6 +82,10 @@ var (
 type Manager struct {
 	backend kvdb.Backend
 
+	// LinkUpdater is a function used by aliasmgr to facilitate live update
+	// of aliases in other subsystems.
+	LinkUpdater UpdateLinkAliases
+
 	// baseToSet is a mapping from the "base" SCID to the set of aliases
 	// for this channel. This mapping includes all channels that
 	// negotiated the option-scid-alias feature bit.
@@ -98,11 +107,14 @@ type Manager struct {
 }
 
 // NewManager initializes an alias Manager from the passed database backend.
-func NewManager(db kvdb.Backend) (*Manager, error) {
+func NewManager(db kvdb.Backend,
+	linkUpdater UpdateLinkAliases) (*Manager, error) {
+
 	m := &Manager{backend: db}
 	m.baseToSet = make(map[lnwire.ShortChannelID][]lnwire.ShortChannelID)
 	m.aliasToBase = make(map[lnwire.ShortChannelID]lnwire.ShortChannelID)
 	m.peerAlias = make(map[lnwire.ChannelID]lnwire.ShortChannelID)
+	m.LinkUpdater = linkUpdater
 
 	err := m.populateMaps()
 	return m, err
@@ -215,12 +227,22 @@ func (m *Manager) populateMaps() error {
 // AddLocalAlias adds a database mapping from the passed alias to the passed
 // base SCID. The gossip boolean marks whether or not to create a mapping
 // that the gossiper will use. It is set to false for the upgrade path where
-// the feature-bit is toggled on and there are existing channels.
+// the feature-bit is toggled on and there are existing channels. The linkUpdate
+// flag is used to signal whether this function should also trigger an update
+// on the htlcswitch scid alias maps.
 func (m *Manager) AddLocalAlias(alias, baseScid lnwire.ShortChannelID,
-	gossip bool) error {
+	gossip, linkUpdate bool) error {
 
+	// We need to lock the manager for the whole duration of this method,
+	// except for the very last part where we call the link updater. In
+	// order for us to safely use a defer _and_ still be able to manually
+	// unlock, we use a sync.Once.
 	m.Lock()
-	defer m.Unlock()
+	unlockOnce := sync.Once{}
+	unlock := func() {
+		unlockOnce.Do(m.Unlock)
+	}
+	defer unlock()
 
 	err := kvdb.Update(m.backend, func(tx kvdb.RwTx) error {
 		// If the caller does not want to allow the alias to be used
@@ -270,6 +292,18 @@ func (m *Manager) AddLocalAlias(alias, baseScid lnwire.ShortChannelID,
 		m.aliasToBase[alias] = baseScid
 	}
 
+	// We definitely need to unlock the Manager before calling the link
+	// updater. If we don't, we'll deadlock. We use a sync.Once to ensure
+	// that we only unlock once.
+	unlock()
+
+	// Finally, we trigger a htlcswitch update if the flag is set, in order
+	// for any future htlc that references the added alias to be properly
+	// routed.
+	if linkUpdate {
+		return m.LinkUpdater(baseScid)
+	}
+
 	return nil
 }
 
@@ -340,6 +374,72 @@ func (m *Manager) DeleteSixConfs(baseScid lnwire.ShortChannelID) error {
 	return nil
 }
 
+// DeleteLocalAlias removes a mapping from the database and the Manager's maps.
+func (m *Manager) DeleteLocalAlias(alias,
+	baseScid lnwire.ShortChannelID) error {
+
+	// We need to lock the manager for the whole duration of this method,
+	// except for the very last part where we call the link updater. In
+	// order for us to safely use a defer _and_ still be able to manually
+	// unlock, we use a sync.Once.
+	m.Lock()
+	unlockOnce := sync.Once{}
+	unlock := func() {
+		unlockOnce.Do(m.Unlock)
+	}
+	defer unlock()
+
+	err := kvdb.Update(m.backend, func(tx kvdb.RwTx) error {
+		aliasToBaseBucket, err := tx.CreateTopLevelBucket(aliasBucket)
+		if err != nil {
+			return err
+		}
+
+		var aliasBytes [8]byte
+		byteOrder.PutUint64(aliasBytes[:], alias.ToUint64())
+
+		return aliasToBaseBucket.Delete(aliasBytes[:])
+	}, func() {})
+	if err != nil {
+		return err
+	}
+
+	// Now that the database state has been updated, we'll delete the
+	// mapping from the Manager's maps.
+	aliasSet, ok := m.baseToSet[baseScid]
+	if !ok {
+		return nil
+	}
+
+	// We'll iterate through the alias set and remove the alias from the
+	// set.
+	for i, a := range aliasSet {
+		if a.ToUint64() == alias.ToUint64() {
+			aliasSet = append(aliasSet[:i], aliasSet[i+1:]...)
+			break
+		}
+	}
+
+	// If the alias set is empty, we'll delete the base SCID from the
+	// baseToSet map.
+	if len(aliasSet) == 0 {
+		delete(m.baseToSet, baseScid)
+	} else {
+		m.baseToSet[baseScid] = aliasSet
+	}
+
+	// Finally, we'll delete the aliasToBase mapping from the Manager's
+	// cache.
+	delete(m.aliasToBase, alias)
+
+	// We definitely need to unlock the Manager before calling the link
+	// updater. If we don't, we'll deadlock. We use a sync.Once to ensure
+	// that we only unlock once.
+	unlock()
+
+	return m.LinkUpdater(baseScid)
+}
+
 // PutPeerAlias stores the peer's alias SCID once we learn of it in the
 // channel_ready message.
 func (m *Manager) PutPeerAlias(chanID lnwire.ChannelID,

aliasmgr/aliasmgr_test.go

@@ -23,7 +23,11 @@ func TestAliasStorePeerAlias(t *testing.T) {
 	require.NoError(t, err)
 	defer db.Close()
 
-	aliasStore, err := NewManager(db)
+	linkUpdater := func(shortID lnwire.ShortChannelID) error {
+		return nil
+	}
+
+	aliasStore, err := NewManager(db, linkUpdater)
 	require.NoError(t, err)
 
 	var chanID1 [32]byte
@@ -52,7 +56,14 @@ func TestAliasStoreRequest(t *testing.T) {
 	require.NoError(t, err)
 	defer db.Close()
 
-	aliasStore, err := NewManager(db)
+	updateChan := make(chan struct{}, 1)
+
+	linkUpdater := func(shortID lnwire.ShortChannelID) error {
+		updateChan <- struct{}{}
+		return nil
+	}
+
+	aliasStore, err := NewManager(db, linkUpdater)
 	require.NoError(t, err)
 
 	// We'll assert that the very first alias we receive is StartingAlias.
@@ -68,6 +79,88 @@ func TestAliasStoreRequest(t *testing.T) {
 	require.Equal(t, nextAlias, alias2)
 }
 
+// TestAliasLifecycle tests that the aliases can be created and deleted.
+func TestAliasLifecycle(t *testing.T) {
+	t.Parallel()
+
+	// Create the backend database and use this to create the aliasStore.
+	dbPath := filepath.Join(t.TempDir(), "testdb")
+	db, err := kvdb.Create(
+		kvdb.BoltBackendName, dbPath, true, kvdb.DefaultDBTimeout,
+	)
+	require.NoError(t, err)
+	defer db.Close()
+
+	updateChan := make(chan struct{}, 1)
+
+	linkUpdater := func(shortID lnwire.ShortChannelID) error {
+		updateChan <- struct{}{}
+		return nil
+	}
+
+	aliasStore, err := NewManager(db, linkUpdater)
+	require.NoError(t, err)
+
+	const (
+		base  = uint64(123123123)
+		alias = uint64(456456456)
+	)
+
+	// Parse the aliases and base to short channel ID format.
+	baseScid := lnwire.NewShortChanIDFromInt(base)
+	aliasScid := lnwire.NewShortChanIDFromInt(alias)
+	aliasScid2 := lnwire.NewShortChanIDFromInt(alias + 1)
+
+	// Add the first alias.
+	err = aliasStore.AddLocalAlias(aliasScid, baseScid, false, true)
+	require.NoError(t, err)
+
+	// The link updater should be called.
+	<-updateChan
+
+	// Query the aliases and verify the results.
+	aliasList := aliasStore.GetAliases(baseScid)
+	require.Len(t, aliasList, 1)
+	require.Contains(t, aliasList, aliasScid)
+
+	// Add the second alias.
+	err = aliasStore.AddLocalAlias(aliasScid2, baseScid, false, true)
+	require.NoError(t, err)
+
+	// The link updater should be called.
+	<-updateChan
+
+	// Query the aliases and verify the results.
+	aliasList = aliasStore.GetAliases(baseScid)
+	require.Len(t, aliasList, 2)
+	require.Contains(t, aliasList, aliasScid)
+	require.Contains(t, aliasList, aliasScid2)
+
+	// Delete the first alias.
+	err = aliasStore.DeleteLocalAlias(aliasScid, baseScid)
+	require.NoError(t, err)
+
+	// The link updater should be called.
+	<-updateChan
+
+	// Query the aliases and verify that first one doesn't exist anymore.
+	aliasList = aliasStore.GetAliases(baseScid)
+	require.Len(t, aliasList, 1)
+	require.Contains(t, aliasList, aliasScid2)
+	require.NotContains(t, aliasList, aliasScid)
+
+	// Delete the second alias.
+	err = aliasStore.DeleteLocalAlias(aliasScid2, baseScid)
+	require.NoError(t, err)
+
+	// The link updater should be called.
+	<-updateChan
+
+	// Query the aliases and verify that none exists.
+	aliasList = aliasStore.GetAliases(baseScid)
+	require.Len(t, aliasList, 0)
+}
+
 // TestGetNextScid tests that given a current lnwire.ShortChannelID,
 // getNextScid returns the expected alias to use next.
 func TestGetNextScid(t *testing.T) {

docs/release-notes/release-notes-0.18.1.md

@@ -0,0 +1,7 @@
+* Some new experimental [RPCs for managing SCID 
+  aliases](https://github.com/lightningnetwork/lnd/pull/8509) were added under
+  the routerrpc package. These methods allow manually adding and deleting scid 
+  aliases locally to your node.
+  > NOTE: these new RPC methods are marked as experimental 
+        (`XAddLocalChanAliases` & `XDeleteLocalChanAliases`) and upon calling
+        them the aliases will not be communicated with the channel peer. 

funding/interfaces.go

@@ -36,7 +36,8 @@ type aliasHandler interface {
 	GetPeerAlias(lnwire.ChannelID) (lnwire.ShortChannelID, error)
 
 	// AddLocalAlias persists an alias to an underlying alias store.
-	AddLocalAlias(lnwire.ShortChannelID, lnwire.ShortChannelID, bool) error
+	AddLocalAlias(lnwire.ShortChannelID, lnwire.ShortChannelID, bool,
+		bool) error
 
 	// GetAliases returns the set of aliases given the main SCID of a
 	// channel. This SCID will be an alias for zero-conf channels and will

funding/manager.go

@@ -1249,7 +1249,7 @@ func (f *Manager) advancePendingChannelState(
 		// Persist the alias to the alias database.
 		baseScid := channel.ShortChannelID
 		err := f.cfg.AliasManager.AddLocalAlias(
-			baseScid, baseScid, true,
+			baseScid, baseScid, true, false,
 		)
 		if err != nil {
 			return fmt.Errorf("error adding local alias to "+
@@ -3108,7 +3108,7 @@ func (f *Manager) handleFundingConfirmation(
 		}
 
 		err = f.cfg.AliasManager.AddLocalAlias(
-			aliasScid, confChannel.shortChanID, true,
+			aliasScid, confChannel.shortChanID, true, false,
 		)
 		if err != nil {
 			return fmt.Errorf("unable to request alias: %w", err)
@@ -3274,7 +3274,7 @@ func (f *Manager) sendChannelReady(completeChan *channeldb.OpenChannel,
 
 				err = f.cfg.AliasManager.AddLocalAlias(
 					alias, completeChan.ShortChannelID,
-					false,
+					false, false,
 				)
 				if err != nil {
 					return err
@@ -3853,7 +3853,7 @@ func (f *Manager) handleChannelReady(peer lnpeer.Peer, //nolint:funlen
 			}
 
 			err = f.cfg.AliasManager.AddLocalAlias(
-				alias, channel.ShortChannelID, false,
+				alias, channel.ShortChannelID, false, false,
 			)
 			if err != nil {
 				log.Errorf("unable to add local alias: %v",

funding/manager_test.go

@@ -161,7 +161,7 @@ func (m *mockAliasMgr) GetPeerAlias(lnwire.ChannelID) (lnwire.ShortChannelID,
 }
 
 func (m *mockAliasMgr) AddLocalAlias(lnwire.ShortChannelID,
-	lnwire.ShortChannelID, bool) error {
+	lnwire.ShortChannelID, bool, bool) error {
 
 	return nil
 }