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

Author: Roasbeef

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"
@@ -699,6 +700,21 @@ func (l *channelLink) syncChanStates() error {
 			"ChannelPoint(%v)", l.channel.ChannelPoint())
 	}
 
+	// If this is a tarpoot channel, then in addition to the normal reest
+	// message, we'll also send our local+remote nonces as well.
+	//
+	// TODO(roasbeef): move into ChanSyncMsg
+	if chanState.ChanType.IsTaproot() {
+		localNonce, err := l.channel.GenMusigNonces()
+		if err != nil {
+			return fmt.Errorf("unable to generate nonce "+
+				"pair for chan: %w", err)
+		}
+		localChanSyncMsg.LocalNonce = (*lnwire.Musig2Nonce)(
+			&localNonce.PubNonce,
+		)
+	}
+
 	if err := l.cfg.Peer.SendMessage(true, localChanSyncMsg); err != nil {
 		return fmt.Errorf("unable to send chan sync message for "+
 			"ChannelPoint(%v): %v", l.channel.ChannelPoint(), err)
@@ -766,6 +782,22 @@ 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")
+
+			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")
 
@@ -1932,6 +1964,7 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 		err = l.channel.ReceiveNewCommitment(&lnwallet.CommitSigs{
 			CommitSig:  msg.CommitSig,
 			HtlcSigs:   msg.HtlcSigs,
+			PartialSig: msg.PartialSig,
 		})
 		if err != nil {
 			// If we were unable to reconstruct their proposed
@@ -2312,6 +2345,7 @@ func (l *channelLink) updateCommitTx() error {
 		ChanID:     l.ChanID(),
 		CommitSig:  newCommit.CommitSig,
 		HtlcSigs:   newCommit.HtlcSigs,
+		PartialSig: newCommit.PartialSig,
 	}
 	l.cfg.Peer.SendMessage(false, commitSig)
 

htlcswitch/mock.go

@@ -666,7 +666,7 @@ func (s *mockServer) Address() net.Addr {
 	return nil
 }
 
-func (s *mockServer) AddNewChannel(channel *channeldb.OpenChannel,
+func (s *mockServer) AddNewChannel(channel *lnpeer.NewChannel,
 	cancel <-chan struct{}) error {
 
 	return nil