htlcswitch: expose custom channel blob from link

htlcswitch/interfaces.go

@@ -13,6 +13,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/record"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 // InvoiceDatabase is an interface which represents the persistent subsystem
@@ -278,6 +279,16 @@ type ChannelLink interface {
 	// have buffered messages.
 	AttachMailBox(MailBox)
 
+	// FundingCustomBlob returns the custom funding blob of the channel that
+	// this link is associated with. The funding blob represents static
+	// information about the channel that was created at channel funding
+	// time.
+	FundingCustomBlob() fn.Option[tlv.Blob]
+
+	// CommitmentCustomBlob returns the custom blob of the current local
+	// commitment of the channel that this link is associated with.
+	CommitmentCustomBlob() fn.Option[tlv.Blob]
+
 	// Start/Stop are used to initiate the start/stop of the channel link
 	// functioning.
 	Start() error

htlcswitch/link.go

@@ -31,6 +31,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/queue"
 	"github.com/lightningnetwork/lnd/ticker"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 func init() {
@@ -4105,3 +4106,28 @@ func (l *channelLink) failf(linkErr LinkFailureError, format string,
 	l.failed = true
 	l.cfg.OnChannelFailure(l.ChanID(), l.ShortChanID(), linkErr)
 }
+
+// FundingCustomBlob returns the custom funding blob of the channel that this
+// link is associated with. The funding blob represents static information about
+// the channel that was created at channel funding time.
+func (l *channelLink) FundingCustomBlob() fn.Option[tlv.Blob] {
+	if l.channel == nil {
+		return fn.None[tlv.Blob]()
+	}
+
+	if l.channel.State() == nil {
+		return fn.None[tlv.Blob]()
+	}
+
+	return l.channel.State().CustomBlob
+}
+
+// CommitmentCustomBlob returns the custom blob of the current local commitment
+// of the channel that this link is associated with.
+func (l *channelLink) CommitmentCustomBlob() fn.Option[tlv.Blob] {
+	if l.channel == nil {
+		return fn.None[tlv.Blob]()
+	}
+
+	return l.channel.LocalCommitmentBlob()
+}

htlcswitch/mock.go

@@ -35,6 +35,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/ticker"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 func isAlias(scid lnwire.ShortChannelID) bool {
@@ -950,6 +951,14 @@ func (f *mockChannelLink) OnCommitOnce(LinkDirection, func()) {
 	// TODO(proofofkeags): Implement
 }
 
+func (f *mockChannelLink) FundingCustomBlob() fn.Option[tlv.Blob] {
+	return fn.None[tlv.Blob]()
+}
+
+func (f *mockChannelLink) CommitmentCustomBlob() fn.Option[tlv.Blob] {
+	return fn.None[tlv.Blob]()
+}
+
 var _ ChannelLink = (*mockChannelLink)(nil)
 
 func newDB() (*channeldb.DB, func(), error) {