channeldb: add persistance of the onion blob

In this commit htlc channeldb representation have been augmented
with onion blob field, and (de)serialisaion functions have been changed
to make the onion blob persistant.

channeldb/channel.go

@@ -532,6 +532,10 @@ type HTLC struct {
 	// Incoming denotes whether we're the receiver or the sender of this
 	// HTLC.
 	Incoming bool
+
+	// OnionBlob is an opaque blob which is used to complete multi-hop
+	// routing.
+	OnionBlob []byte
 }
 
 // Copy returns a full copy of the target HTLC.
@@ -2084,17 +2088,27 @@ func serializeHTLC(w io.Writer, h *HTLC) error {
 		return err
 	}
 
+	var onionLength [2]byte
+	byteOrder.PutUint16(onionLength[:], uint16(len(h.OnionBlob)))
+	if _, err := w.Write(onionLength[:]); err != nil {
+		return err
+	}
+
+	if _, err := w.Write(h.OnionBlob); err != nil {
+		return err
+	}
+
 	return nil
 }
 
 func deserializeHTLC(r io.Reader) (*HTLC, error) {
 	h := &HTLC{}
+	var err error
 
-	sigBytes, err := wire.ReadVarBytes(r, 0, 80, "")
+	h.Signature, err = wire.ReadVarBytes(r, 0, 80, "")
 	if err != nil {
 		return nil, err
 	}
-	h.Signature = sigBytes
 
 	if _, err := io.ReadFull(r, h.RHash[:]); err != nil {
 		return nil, err
@@ -2115,12 +2129,25 @@ func deserializeHTLC(r io.Reader) (*HTLC, error) {
 		return nil, err
 	}
 
-	if scratch[0] == 1 {
+	if boolByte[0] == 1 {
 		h.Incoming = true
 	} else {
 		h.Incoming = false
 	}
 
+	var onionLength [2]byte
+	if _, err := r.Read(onionLength[:]); err != nil {
+		return nil, err
+	}
+
+	l := byteOrder.Uint16(onionLength[:])
+	if l != 0 {
+		h.OnionBlob = make([]byte, l)
+		if _, err := io.ReadFull(r, h.OnionBlob); err != nil {
+			return nil, err
+		}
+	}
+
 	return h, nil
 }
 

channeldb/channel_test.go

@@ -207,6 +207,7 @@ func TestOpenChannelPutGetDelete(t *testing.T) {
 			Amt:           10,
 			RHash:         key,
 			RefundTimeout: 1,
+			OnionBlob:       []byte("onionblob"),
 		},
 	}
 	if err := state.FullSync(); err != nil {