channeldb: define a single AddrSource interface

Our aim is to completely remove the `channeldb.DB`'s direct dependence
on the `graphdb.ChannelGraph` pointer. The only place where it still
depends on this pointer is in the `(DB).AddrsForNode(..)` method where
it queries both the channel DB and the graph db for the known addresses
for the node in question and then combines the results. So, to separate
these out, we will define an AddrsForNodes interface in this commit
which we will later let both the ChannelGraph and channeldb.DB both
implement and we will merge these results outside of the channeldb
package.

All this commit does is to unify the `AddrSource` interface since this
has been defined separately in a couple of places.

chanbackup/backup.go

@@ -2,9 +2,7 @@ package chanbackup
 
 import (
 	"fmt"
-	"net"
 
-	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/fn"
@@ -24,19 +22,11 @@ type LiveChannelSource interface {
 		*channeldb.OpenChannel, error)
 }
 
-// AddressSource is an interface that allows us to query for the set of
-// addresses a node can be connected to.
-type AddressSource interface {
-	// AddrsForNode returns all known addresses for the target node public
-	// key.
-	AddrsForNode(nodePub *btcec.PublicKey) ([]net.Addr, error)
-}
-
 // assembleChanBackup attempts to assemble a static channel backup for the
 // passed open channel. The backup includes all information required to restore
 // the channel, as well as addressing information so we can find the peer and
 // reconnect to them to initiate the protocol.
-func assembleChanBackup(addrSource AddressSource,
+func assembleChanBackup(addrSource channeldb.AddrSource,
 	openChan *channeldb.OpenChannel) (*Single, error) {
 
 	log.Debugf("Crafting backup for ChannelPoint(%v)",
@@ -100,7 +90,7 @@ func buildCloseTxInputs(
 // the target channel identified by its channel point. If we're unable to find
 // the target channel, then an error will be returned.
 func FetchBackupForChan(chanPoint wire.OutPoint, chanSource LiveChannelSource,
-	addrSource AddressSource) (*Single, error) {
+	addrSource channeldb.AddrSource) (*Single, error) {
 
 	// First, we'll query the channel source to see if the channel is known
 	// and open within the database.
@@ -124,7 +114,7 @@ func FetchBackupForChan(chanPoint wire.OutPoint, chanSource LiveChannelSource,
 // FetchStaticChanBackups will return a plaintext static channel back up for
 // all known active/open channels within the passed channel source.
 func FetchStaticChanBackups(chanSource LiveChannelSource,
-	addrSource AddressSource) ([]Single, error) {
+	addrSource channeldb.AddrSource) ([]Single, error) {
 
 	// First, we'll query the backup source for information concerning all
 	// currently open and available channels.

channel_notifier.go

@@ -2,24 +2,13 @@ package lnd
 
 import (
 	"fmt"
-	"net"
 
-	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/chanbackup"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channelnotifier"
 )
 
-// addrSource is an interface that allow us to get the addresses for a target
-// node. We'll need this in order to be able to properly proxy the
-// notifications to create SCBs.
-type addrSource interface {
-	// AddrsForNode returns all known addresses for the target node public
-	// key.
-	AddrsForNode(nodePub *btcec.PublicKey) ([]net.Addr, error)
-}
-
 // channelNotifier is an implementation of the chanbackup.ChannelNotifier
 // interface using the existing channelnotifier.ChannelNotifier struct. This
 // implementation allows us to satisfy all the dependencies of the
@@ -32,7 +21,7 @@ type channelNotifier struct {
 	// addrs is an implementation of the addrSource interface that allows
 	// us to get the latest set of addresses for a given node. We'll need
 	// this to be able to create an SCB for new channels.
-	addrs addrSource
+	addrs channeldb.AddrSource
 }
 
 // SubscribeChans requests a new channel subscription relative to the initial

channeldb/addr_source.go

@@ -0,0 +1,15 @@
+package channeldb
+
+import (
+	"net"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+)
+
+// AddrSource is an interface that allow us to get the addresses for a target
+// node. It may combine the results of multiple address sources.
+type AddrSource interface {
+	// AddrsForNode returns all known addresses for the target node public
+	// key.
+	AddrsForNode(nodePub *btcec.PublicKey) ([]net.Addr, error)
+}

server.go

@@ -263,7 +263,7 @@ type server struct {
 
 	chanStateDB *channeldb.ChannelStateDB
 
-	addrSource chanbackup.AddressSource
+	addrSource channeldb.AddrSource
 
 	// miscDB is the DB that contains all "other" databases within the main
 	// channel DB that haven't been separated out yet.