Add capability-id and context-id rlp list in header-data for Parity compatibility

eth/p2p/rlpxcrypt.nim

@@ -141,6 +141,13 @@ proc encryptMsg*(msg: openarray[byte], secrets: var SecretState): seq[byte] =
   header[1] = byte((msg.len shr 8) and 0xFF)
   header[2] = byte(msg.len and 0xFF)
 
+  # This is the  [capability-id, context-id] in header-data
+  # While not really used, this is checked in the Parity client.
+  # Same as rlp.encode((0, 0))
+  header[3] = 0xc2
+  header[4] = 0x80
+  header[5] = 0x80
+
   # XXX:
   # This would be safer if we use a thread-local sequ for the temporary buffer
   result = newSeq[byte](encryptedLength(msg.len))