Wireshark Lua Dissector - 如何使用 TAP？

我想在我的 Lua Dissector 中解析自定义协议的数据，然后进行一些分析。我试图这样做：

myproto_proto = Proto("myproto", "Myproto Protocol")
m_dest = ProtoField.uint16("myproto.dest", "Destination", base.HEX)
m_src = ProtoField.uint16("myproto.src", "Source", base.HEX)
myproto_proto.fields = { sm_dest, sm_src }

dofile(MYPROTO_PROTO_PATH.."parser.lua")

function myproto_proto.dissector(buffer, pinfo, tree)
   pinfo.cols.protocol = "MYPROTO"

   local subtree = tree:add(myproto_proto, buffer(), "Myproto Protocol Data")
   parse_msg(buffer, pinfo, subtree) -- does the actual parsing and sets the fields
end

udp_table = DissectorTable.get("udp.port")
udp_table:add(9000,myproto_proto)

-- LISTENER / TAP

f_test = Field.new("myproto.dest") -- fails because "field does not exist"
local function my_tap()
   local window = TextWindow.new("Myproto Tap")
   local tap = Listener.new(nil, "myproto")

   local counter = 0
   function remove()
      tap:remove()
   end

   window:set_atclose(remove)

   function tap.packet(pinfo, buffer)
      counter = counter + 1
   end

   function tap.draw(t)
      window:append("Counter: \t" .. counter .. "\n")
   end

   function tap.reset()
      window:clear()
      counter = 0
   end
   retap_packets()
end

register_menu("My Tap", my_tap, MENU_TOOLS_UNSORTED)

我的问题是，我无法使用字段提取器访问解析的数据。那么我该如何在我的 Lua Tap 中获得解析的数据呢？

预先感谢您的帮助。