lnwallet: make second level sigs using sighash single|anyonecanpay

lnwallet/commitment.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/btcsuite/btcd/blockchain"
 	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/channeldb"
@@ -224,6 +225,16 @@ func CommitScriptToRemote(chanType channeldb.ChannelType,
 	}, 0, nil
 }
 
+// HtlcSigHashType returns the sighash type to use for HTLC success and timeout
+// transactions given the channel type.
+func HtlcSigHashType(chanType channeldb.ChannelType) txscript.SigHashType {
+	if chanType.HasAnchors() {
+		return txscript.SigHashSingle | txscript.SigHashAnyOneCanPay
+	}
+
+	return txscript.SigHashAll
+}
+
 // CommitWeight returns the base commitment weight before adding HTLCs.
 func CommitWeight(chanType channeldb.ChannelType) int64 {
 	// If this commitment has anchors, it will be slightly heavier.