From f41dd862d06642f15cb47fac21227f3ab88d07fe Mon Sep 17 00:00:00 2001
From: Olaoluwa Osuntokun <laolu32@gmail.com>
Date: Thu, 29 Aug 2024 21:19:31 -0500
Subject: [PATCH] htlcswitch+lnwallet: use CustomRecords for aux sig blobs

In this commit, we start to use the set of CustomRecords instead of ExtraData for the aux sig blobs.
---
 htlcswitch/link.go  | 27 +++++++++++++++++++++------
 lnwallet/channel.go | 35 +++++++++++++++++++++++++++--------
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/htlcswitch/link.go b/htlcswitch/link.go
index 468eba131..a59cedf06 100644
--- a/htlcswitch/link.go
+++ b/htlcswitch/link.go
@@ -2164,11 +2164,21 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 		// We just received a new updates to our local commitment
 		// chain, validate this new commitment, closing the link if
 		// invalid.
+		auxSigBlob, err := msg.CustomRecords.Serialize()
+		if err != nil {
+			l.fail(
+				LinkFailureError{code: ErrInternalError},
+				"unable to serialize custom records: %v",
+				err,
+			)
+
+			return
+		}
 		err = l.channel.ReceiveNewCommitment(&lnwallet.CommitSigs{
 			CommitSig:  msg.CommitSig,
 			HtlcSigs:   msg.HtlcSigs,
 			PartialSig: msg.PartialSig,
-			AuxSigBlob: msg.ExtraData,
+			AuxSigBlob: auxSigBlob,
 		})
 		if err != nil {
 			// If we were unable to reconstruct their proposed
@@ -2577,12 +2587,17 @@ func (l *channelLink) updateCommitTx() error {
 	default:
 	}
 
+	auxBlobRecords, err := lnwire.ParseCustomRecords(newCommit.AuxSigBlob)
+	if err != nil {
+		return fmt.Errorf("error parsing aux sigs: %w", err)
+	}
+
 	commitSig := &lnwire.CommitSig{
-		ChanID:     l.ChanID(),
-		CommitSig:  newCommit.CommitSig,
-		HtlcSigs:   newCommit.HtlcSigs,
-		PartialSig: newCommit.PartialSig,
-		ExtraData:  newCommit.AuxSigBlob,
+		ChanID:        l.ChanID(),
+		CommitSig:     newCommit.CommitSig,
+		HtlcSigs:      newCommit.HtlcSigs,
+		PartialSig:    newCommit.PartialSig,
+		CustomRecords: auxBlobRecords,
 	}
 	l.cfg.Peer.SendMessage(false, commitSig)
 
diff --git a/lnwallet/channel.go b/lnwallet/channel.go
index 0c3e4c9ce..b420b6134 100644
--- a/lnwallet/channel.go
+++ b/lnwallet/channel.go
@@ -4028,6 +4028,10 @@ func (lc *LightningChannel) createCommitDiff(newCommit *commitment,
 	if err != nil {
 		return nil, fmt.Errorf("error packing aux sigs: %w", err)
 	}
+	auxBlobRecords, err := lnwire.ParseCustomRecords(auxSigBlob)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing aux sigs: %w", err)
+	}
 
 	return &channeldb.CommitDiff{
 		Commitment: *diskCommit,
@@ -4035,9 +4039,9 @@ func (lc *LightningChannel) createCommitDiff(newCommit *commitment,
 			ChanID: lnwire.NewChanIDFromOutPoint(
 				lc.channelState.FundingOutpoint,
 			),
-			CommitSig: commitSig,
-			HtlcSigs:  htlcSigs,
-			ExtraData: auxSigBlob,
+			CommitSig:     commitSig,
+			HtlcSigs:      htlcSigs,
+			CustomRecords: auxBlobRecords,
 		},
 		LogUpdates:        logUpdates,
 		OpenedCircuitKeys: openCircuitKeys,
@@ -4737,12 +4741,18 @@ func (lc *LightningChannel) SignNextCommitment() (*NewCommitState, error) {
 	// latest commitment update.
 	lc.remoteCommitChain.addCommitment(newCommitView)
 
+	auxSigBlob, err := commitDiff.CommitSig.CustomRecords.Serialize()
+	if err != nil {
+		return nil, fmt.Errorf("unable to serialize aux sig "+
+			"blob: %v", err)
+	}
+
 	return &NewCommitState{
 		CommitSigs: &CommitSigs{
 			CommitSig:  sig,
 			HtlcSigs:   htlcSigs,
 			PartialSig: lnwire.MaybePartialSigWithNonce(partialSig),
-			AuxSigBlob: commitDiff.CommitSig.ExtraData,
+			AuxSigBlob: auxSigBlob,
 		},
 		PendingHTLCs: commitDiff.Commitment.Htlcs,
 	}, nil
@@ -4960,14 +4970,23 @@ func (lc *LightningChannel) ProcessChanSyncMsg(
 			// If we signed this state, then we'll accumulate
 			// another update to send over.
 			case err == nil:
+				blobRecords, err := lnwire.ParseCustomRecords(
+					newCommit.AuxSigBlob,
+				)
+				if err != nil {
+					sErr := fmt.Errorf("error parsing "+
+						"aux sigs: %w", err)
+					return nil, nil, nil, sErr
+				}
+
 				commitSig := &lnwire.CommitSig{
 					ChanID: lnwire.NewChanIDFromOutPoint(
 						lc.channelState.FundingOutpoint,
 					),
-					CommitSig:  newCommit.CommitSig,
-					HtlcSigs:   newCommit.HtlcSigs,
-					PartialSig: newCommit.PartialSig,
-					ExtraData:  newCommit.AuxSigBlob,
+					CommitSig:     newCommit.CommitSig,
+					HtlcSigs:      newCommit.HtlcSigs,
+					PartialSig:    newCommit.PartialSig,
+					CustomRecords: blobRecords,
 				}
 
 				updates = append(updates, commitSig)