From ec7dc031c9b391a023be4ee72ed7e8a0448d3313 Mon Sep 17 00:00:00 2001
From: George Tsagkarelis <george.tsagkarelis@gmail.com>
Date: Thu, 2 May 2024 16:52:47 +0200
Subject: [PATCH] htlcswitch: expose custom channel blob from link

---
 htlcswitch/interfaces.go | 11 +++++++++++
 htlcswitch/link.go       | 13 +++++++++++++
 htlcswitch/mock.go       | 14 ++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/htlcswitch/interfaces.go b/htlcswitch/interfaces.go
index eda85cfb0..0bada0d10 100644
--- a/htlcswitch/interfaces.go
+++ b/htlcswitch/interfaces.go
@@ -12,6 +12,7 @@ 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
@@ -271,6 +272,16 @@ 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
diff --git a/htlcswitch/link.go b/htlcswitch/link.go
index 8eca0f004..ab4284d62 100644
--- a/htlcswitch/link.go
+++ b/htlcswitch/link.go
@@ -3775,3 +3775,16 @@ func (l *channelLink) fail(linkErr LinkFailureError,
 	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] {
+	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] {
+	return l.channel.LocalCommitmentBlob()
+}
diff --git a/htlcswitch/mock.go b/htlcswitch/mock.go
index a0f38c74f..c56b47548 100644
--- a/htlcswitch/mock.go
+++ b/htlcswitch/mock.go
@@ -27,6 +27,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb/models"
 	"github.com/lightningnetwork/lnd/clock"
 	"github.com/lightningnetwork/lnd/contractcourt"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/htlcswitch/hop"
 	"github.com/lightningnetwork/lnd/invoices"
 	"github.com/lightningnetwork/lnd/lnpeer"
@@ -35,6 +36,7 @@ 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 {
@@ -912,6 +914,10 @@ func (f *mockChannelLink) ChannelPoint() wire.OutPoint {
 	return wire.OutPoint{}
 }
 
+func (f *mockChannelLink) ChannelCustomBlob() fn.Option[tlv.Blob] {
+	return fn.Option[tlv.Blob]{}
+}
+
 func (f *mockChannelLink) Stop()                                        {}
 func (f *mockChannelLink) EligibleToForward() bool                      { return f.eligible }
 func (f *mockChannelLink) MayAddOutgoingHtlc(lnwire.MilliSatoshi) error { return nil }
@@ -942,6 +948,14 @@ 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) {