I have packet with trailer data after the packet as in ixia timestamp trailer. I am trying to write a dissector for Wireshark that is quite the same as ixia-packet_trailer plugin. https://raw.githubusercontent.com/boundary/wireshark/master/epan/dissectors/packet-ixiatrailer.c
But i wanted to write in Lua, so it is easiest to change.
I did the lua as heuristic with the function is_my_trailer (as proposed in Wireshark Lua dissector plugin table error), it now stop to show the trailer in ethernet tree so i believe it recognize the pattern 0xae12, but it doesn't show my "my trailer" tree
-- Header fields
local timestamp = ProtoField.uint64 ("my_trailer_proto.timestamp", "timestamp", base.HEX)
local proto_flag = ProtoField.uint8 ("my_trailer_proto.proto_flag", "protoFlag", base.HEX)
local msg_id = ProtoField.uint16("my_trailer_proto.msg_id" , "msdId" , base.HEX)
my_trailer_proto.fields = { timestamp, proto_flag, msg_id }
-- does this packet contains a trailer
local function is_my_trailer(buffer,pinfo,tree)
local length = buffer:len()
if length < 12 then return 1 end
local type = buffer(length-12, 2):uint()
if type == 0xae12 then return true end
return false
end
function my_trailer_proto.dissector(buffer, pinfo, tree)
length = buffer:len()
if length == 0 then return end
local subtree = tree:add(my_trailer_proto, buffer(), "my trailer")
-- Header
subtree:add(timestamp, buffer(length-10,8))
subtree:add(proto_flag, buffer(length-3,1))
subtree:add(msg_id, buffer(length-2,2))
pinfo.cols.protocol = my_trailer_proto.name
pinfo.cols.protocol:set("proto_flag")
pinfo.cols.info:set("proto_flag: " .. proto_flag)
end
my_trailer_proto:register_heuristic("eth.trailer", is_my_trailer)
