public void openBook(ItemStack book, Player p) {
        int slot = p.getInventory().getHeldItemSlot();
        ItemStack old = p.getInventory().getItem(slot);
        p.getInventory().setItem(slot, book);

       ByteBuf buf = Unpooled.buffer(256);
       buf.setByte(0, (byte)0);
       buf.writerIndex(1);

        PacketPlayOutCustomPayload packet = new PacketPlayOutCustomPayload("MC|BOpen", new PacketDataSerializer(buf));
        ((CraftPlayer)p).getHandle().playerConnection.sendPacket(packet);
        p.getInventory().setItem(slot, old);
    }