lnwire: add ChannelUpdate2

Add the new ChannelUpdate2 message and ensure that it implements the
ChannelUpdate interface.

lnwire/msat.go

@@ -2,8 +2,10 @@ package lnwire
 
 import (
 	"fmt"
+	"io"
 
 	"github.com/btcsuite/btcd/btcutil"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 const (
@@ -49,3 +51,40 @@ func (m MilliSatoshi) String() string {
 }
 
 // TODO(roasbeef): extend with arithmetic operations?
+
+// Record returns a TLV record that can be used to encode/decode a MilliSatoshi
+// to/from a TLV stream.
+func (m *MilliSatoshi) Record() tlv.Record {
+	return tlv.MakeDynamicRecord(
+		0, m, tlv.SizeBigSize(m), encodeMilliSatoshis,
+		decodeMilliSatoshis,
+	)
+}
+
+func encodeMilliSatoshis(w io.Writer, val interface{}, buf *[8]byte) error {
+	if v, ok := val.(*MilliSatoshi); ok {
+		bigSize := uint64(*v)
+
+		return tlv.EBigSize(w, &bigSize, buf)
+	}
+
+	return tlv.NewTypeForEncodingErr(val, "lnwire.MilliSatoshi")
+}
+
+func decodeMilliSatoshis(r io.Reader, val interface{}, buf *[8]byte,
+	l uint64) error {
+
+	if v, ok := val.(*MilliSatoshi); ok {
+		var bigSize uint64
+		err := tlv.DBigSize(r, &bigSize, buf, l)
+		if err != nil {
+			return err
+		}
+
+		*v = MilliSatoshi(bigSize)
+
+		return nil
+	}
+
+	return tlv.NewTypeForDecodingErr(val, "lnwire.MilliSatoshi", l, l)
+}