watchtower/multi: send connection features + chain hash in Init

watchtower/wtwire/wtwire.go

@@ -6,8 +6,10 @@ import (
 	"io"
 
 	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/watchtower/blob"
 )
 
@@ -86,6 +88,20 @@ func WriteElement(w io.Writer, element interface{}) error {
 			return err
 		}
 
+	case chainhash.Hash:
+		if _, err := w.Write(e[:]); err != nil {
+			return err
+		}
+
+	case *lnwire.RawFeatureVector:
+		if e == nil {
+			return fmt.Errorf("cannot write nil feature vector")
+		}
+
+		if err := e.Encode(w); err != nil {
+			return err
+		}
+
 	case *btcec.PublicKey:
 		if e == nil {
 			return fmt.Errorf("cannot write nil pubkey")
@@ -192,6 +208,20 @@ func ReadElement(r io.Reader, element interface{}) error {
 		}
 		*e = ErrorCode(binary.BigEndian.Uint16(b[:]))
 
+	case *chainhash.Hash:
+		if _, err := io.ReadFull(r, e[:]); err != nil {
+			return err
+		}
+
+	case **lnwire.RawFeatureVector:
+		f := lnwire.NewRawFeatureVector()
+		err := f.Decode(r)
+		if err != nil {
+			return err
+		}
+
+		*e = f
+
 	case **btcec.PublicKey:
 		var b [btcec.PubKeyBytesLenCompressed]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {