Add XFindBaseLocalChanAlias RPC

aliasmgr/aliasmgr.go

@@ -239,14 +239,43 @@ func (m *Manager) populateMaps() error {
 	return nil
 }
 
+// addAliasCfg is a struct that hosts various options related to adding a local
+// alias to the alias manager.
+type addAliasCfg struct {
+	// baseLookup signals that the alias should also store a reverse look-up
+	// to the base scid.
+	baseLookup bool
+}
+
+// AddLocalAliasOption is a functional option that modifies the configuration
+// for adding a local alias.
+type AddLocalAliasOption func(cfg *addAliasCfg)
+
+// WithBaseLookup is a functional option that controls whether a reverse lookup
+// will be stored from the alias to the base scid.
+func WithBaseLookup() AddLocalAliasOption {
+	return func(cfg *addAliasCfg) {
+		cfg.baseLookup = true
+	}
+}
+
 // 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 linkUpdate
-// flag is used to signal whether this function should also trigger an update
-// on the htlcswitch scid alias maps.
+// flag is used to signal whether this function should also trigger an update on
+// the htlcswitch scid alias maps.
+//
+// NOTE: The following aliases will not be persisted (will be lost on restart):
+//   - Aliases that were created without gossip flag.
+//   - Aliases that correspond to confirmed channels.
 func (m *Manager) AddLocalAlias(alias, baseScid lnwire.ShortChannelID,
-	gossip, linkUpdate bool) error {
+	gossip, linkUpdate bool, opts ...AddLocalAliasOption) error {
+
+	cfg := addAliasCfg{}
+	for _, opt := range opts {
+		opt(&cfg)
+	}
 
 	// 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
@@ -302,8 +331,9 @@ func (m *Manager) AddLocalAlias(alias, baseScid lnwire.ShortChannelID,
 	// Update the aliasToBase and baseToSet maps.
 	m.baseToSet[baseScid] = append(m.baseToSet[baseScid], alias)
 
-	// Only store the gossiper map if gossip is true.
-	if gossip {
+	// Only store the gossiper map if gossip is true, or if the caller
+	// explicitly asked to store this reverse mapping.
+	if gossip || cfg.baseLookup {
 		m.aliasToBase[alias] = baseScid
 	}
 
@@ -342,7 +372,9 @@ func (m *Manager) GetAliases(
 }
 
 // FindBaseSCID finds the base SCID for a given alias. This is used in the
-// gossiper to find the correct SCID to lookup in the graph database.
+// gossiper to find the correct SCID to lookup in the graph database. It can
+// also be used to look up the base for manual aliases that were added over the
+// RPC.
 func (m *Manager) FindBaseSCID(
 	alias lnwire.ShortChannelID) (lnwire.ShortChannelID, error) {
 
@@ -446,7 +478,7 @@ func (m *Manager) DeleteLocalAlias(alias,
 	}
 
 	// Finally, we'll delete the aliasToBase mapping from the Manager's
-	// cache (but this is only set if we gossip the alias).
+	// cache.
 	delete(m.aliasToBase, alias)
 
 	// We definitely need to unlock the Manager before calling the link

aliasmgr/aliasmgr_test.go

@@ -179,10 +179,19 @@ func TestAliasLifecycle(t *testing.T) {
 	require.Equal(t, StartingAlias, firstRequested)
 
 	// We now manually add the next alias from the range as a custom alias.
+	// This time we also use the base lookup option, in order to be able to
+	// go from alias back to the base scid.
 	secondAlias := getNextScid(firstRequested)
-	err = aliasStore.AddLocalAlias(secondAlias, baseScid, false, true)
+	err = aliasStore.AddLocalAlias(
+		secondAlias, baseScid, false, true, WithBaseLookup(),
+	)
+	require.NoError(t, err)
+
+	baseLookup, err := aliasStore.FindBaseSCID(secondAlias)
 	require.NoError(t, err)
 
+	require.Equal(t, baseScid, baseLookup)
+
 	// When we now request another alias from the allocation list, we expect
 	// the third one (tx position 2) to be returned.
 	thirdRequested, err := aliasStore.RequestAlias()

docs/release-notes/release-notes-0.20.0.md

@@ -62,6 +62,12 @@ a certain amount of msats.
 - Added support for [P2TR Fallback Addresses](
   https://github.com/lightningnetwork/lnd/pull/9975) in BOLT-11 invoices.
 
+- A new experimental RPC endpoint
+  [XFindBaseLocalChanAlias](https://github.com/lightningnetwork/lnd/pull/10133)
+  was added for looking up the base scid for an scid alias. Aliases that were
+  manually created via the `XAddLocalChanAliases` endpoint will get lost on
+  restart.
+
 ## Functional Enhancements
 * [Add](https://github.com/lightningnetwork/lnd/pull/9677)
   `ConfirmationsUntilActive` and `ConfirmationHeight` field to the

funding/interfaces.go

@@ -1,6 +1,7 @@
 package funding
 
 import (
+	"github.com/lightningnetwork/lnd/aliasmgr"
 	"github.com/lightningnetwork/lnd/lnpeer"
 	"github.com/lightningnetwork/lnd/lnwire"
 )
@@ -36,8 +37,8 @@ type aliasHandler interface {
 	GetPeerAlias(lnwire.ChannelID) (lnwire.ShortChannelID, error)
 
 	// AddLocalAlias persists an alias to an underlying alias store.
-	AddLocalAlias(lnwire.ShortChannelID, lnwire.ShortChannelID, bool,
-		bool) error
+	AddLocalAlias(lnwire.ShortChannelID, lnwire.ShortChannelID, bool, bool,
+		...aliasmgr.AddLocalAliasOption) 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_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcwallet/wallet"
+	"github.com/lightningnetwork/lnd/aliasmgr"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/chainreg"
 	acpt "github.com/lightningnetwork/lnd/chanacceptor"
@@ -162,7 +163,8 @@ func (m *mockAliasMgr) GetPeerAlias(lnwire.ChannelID) (lnwire.ShortChannelID,
 }
 
 func (m *mockAliasMgr) AddLocalAlias(lnwire.ShortChannelID,
-	lnwire.ShortChannelID, bool, bool) error {
+	lnwire.ShortChannelID, bool, bool,
+	...aliasmgr.AddLocalAliasOption) error {
 
 	return nil
 }