htlcswitch: add awareness of new partial sig fields and musig2 nonces

htlcswitch/link.go

@@ -10,6 +10,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btclog"
@@ -772,6 +773,26 @@ func (l *channelLink) syncChanStates() error {
 			}
 		}
 
+		// Before we process the ChanSync message, if this is a taproot
+		// channel, then we'll init our musig2 nonces state.
+		if chanState.ChanType.IsTaproot() {
+			l.log.Infof("initializing musig2 nonces")
+
+			if remoteChanSyncMsg.LocalNonce == nil {
+				return fmt.Errorf("remote nonce is nil")
+			}
+
+			syncMsg := remoteChanSyncMsg
+			remoteNonce := &musig2.Nonces{
+				PubNonce: *syncMsg.LocalNonce,
+			}
+			err := l.channel.InitRemoteMusigNonces(remoteNonce)
+			if err != nil {
+				return fmt.Errorf("unable to init musig2 "+
+					"nonces: %w", err)
+			}
+		}
+
 		// In any case, we'll then process their ChanSync message.
 		l.log.Info("received re-establishment message from remote side")
 
@@ -1936,8 +1957,9 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 		// chain, validate this new commitment, closing the link if
 		// invalid.
 		err = l.channel.ReceiveNewCommitment(&lnwallet.CommitSigs{
-			CommitSig: msg.CommitSig,
-			HtlcSigs:  msg.HtlcSigs,
+			CommitSig:  msg.CommitSig,
+			HtlcSigs:   msg.HtlcSigs,
+			PartialSig: msg.PartialSig,
 		})
 		if err != nil {
 			// If we were unable to reconstruct their proposed
@@ -2315,9 +2337,10 @@ func (l *channelLink) updateCommitTx() error {
 	}
 
 	commitSig := &lnwire.CommitSig{
-		ChanID:    l.ChanID(),
-		CommitSig: newCommit.CommitSig,
-		HtlcSigs:  newCommit.HtlcSigs,
+		ChanID:     l.ChanID(),
+		CommitSig:  newCommit.CommitSig,
+		HtlcSigs:   newCommit.HtlcSigs,
+		PartialSig: newCommit.PartialSig,
 	}
 	l.cfg.Peer.SendMessage(false, commitSig)