lnwire: fix MilliSatoshi Record Size

In this commit we start validating TLV blobs when we decode them. This
exposed a bug where the incorrect size was being used for the
MilliSatoshi TLV record type. So this is fixed here too.

Author: ellemouton

channeldb/migration/lnwire21/msat.go

@@ -55,8 +55,10 @@ func (m MilliSatoshi) String() string {
 // 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 {
+	msat := uint64(*m)
+
 	return tlv.MakeDynamicRecord(
-		0, m, tlv.SizeBigSize(m), encodeMilliSatoshis,
+		0, m, tlv.SizeBigSize(&msat), encodeMilliSatoshis,
 		decodeMilliSatoshis,
 	)
 }

lnwire/extra_bytes.go

@@ -60,6 +60,17 @@ func (e *ExtraOpaqueData) Decode(r io.Reader) error {
 		*e = make([]byte, 0)
 	}
 
+	tlvStream, err := tlv.NewStream()
+	if err != nil {
+		return err
+	}
+
+	// Ensure that the TLV stream is valid by attempting to decode it.
+	_, err = tlvStream.DecodeWithParsedTypesP2P(bytes.NewReader(*e))
+	if err != nil {
+		return fmt.Errorf("invalid TLV stream: %w: %v", err, *e)
+	}
+
 	return nil
 }
 

lnwire/msat.go

@@ -55,8 +55,10 @@ func (m MilliSatoshi) String() string {
 // 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 {
+	msat := uint64(*m)
+
 	return tlv.MakeDynamicRecord(
-		0, m, tlv.SizeBigSize(m), encodeMilliSatoshis,
+		0, m, tlv.SizeBigSize(&msat), encodeMilliSatoshis,
 		decodeMilliSatoshis,
 	)
 }