Declaring fields of chained dissectors in lua

Question

Hi,

I started to make a lua port of the PTP/IP dissector split into the PTP/IP part and an dependent an PTP part. The idea is the PTP/IP dissector parses the IP specific structure parts (length, packet type) and then passes these to an PTP packet dissector.

However, in the PTP dissector I can not declare the 'imported' fields of the PTP/IP dissector:

top level

local length_field = Field.new("ptp.length")
local packet_type_field = Field.new("ptp.pktType")   
local header_offset_field = Field.new("ptp.headerOffset") -- protocol specific offset from the PTP/IP or PTP dissector

results in an error message bad argument #1 to 'new' (Field new: a field with this name must exist).

When I move it to function ptp_proto.dissector(tvb,pinfo,tree) the error message is (Field new: A Field extractor must be defined before Taps or Dissectors are called)

Accepted Answer

Maybe this is due to the order which Wireshark finds & executes your .lua files. Try creating a new script that initializes your dissectors in correct order.

Renaming your files in alphabetical order could also work .. if sorting order of read .lua files is the issue.