I’m not sure what you’re trying to do, but there’s already a Wireshark built-in
dissector for GeoNetworking[1].
If you’re trying to replace it for some reason, then you may either need to
disable that one or remove it completely. And if you’re trying to implement in
Lua, then you’ll need to register it as a heuristic dissector using
register_heuristic[2]. However, it seems that there might be a bug with
respect to this function[3], as the following simple Lua script seems to
indicate:
local p_gnw = Proto("gnwHdr", "GeoNetworkingHdr")
function p_gnw.dissector(tvbuf, pinfo, tree)
local ethertype = tvbuf(12, 2):uint()
if ethertype == 35143 then
pinfo.cols.protocol:set("GNW")
return true
else
return false
end
end
p_gnw.register_heuristic("eth", p_gnw.dissector)
When Wireshark is started with this gnw.lua script loaded, the following error
message is encountered:
Lua: Error during loading:
path\to\gnw.lua:14:bad
argument #1 to ‘register_heuristic’ (userdata expected, got string)
stack traceback:
[C]: in function ‘register_heuristic’
path\to\gnw.lua:14:
in main chunk
- Chris
[1]:
https://code.wireshark.org/review/gitweb?p=wireshark.git;a=blob;f=epan/dissectors/packet-geonw.c;h=21290a3b179c8974483a2f762cbe512fbec67103;hb=HEAD
[2]: https://www.wireshark.org/docs/wsdg_html_chunked/lua_module_Proto.html
(Section 11.6.5.3)
[3]:
https://osqa-ask.wireshark.org/questions/54158/register-heuristic-function-for-multiple-heuristic-list-names-in-lua
From: Wireshark-dev <wireshark-dev-boun...@wireshark.org> On Behalf Of sandip
gangakhedkar
Sent: Wednesday, February 12, 2020 4:46 PM
To: wireshark-dev@wireshark.org
Subject: [Wireshark-dev] Unable to detect custom protocol dissector
Hi,
I am using a Custom protocol dissector (Lua script) for the GeoNetworking
header. I have build wireshark 3.2.1 from source on Ubuntu 18.04 and placed the
Lua script in the Global plugins directory. However, the script fails when to
find the Geonetworking protocol when I invoke it in the script:
Dissector.get("gnw"):call(newTvb, pkt, root)
So I tried another approach:
gnw_dissector = DissectorTable.get("ethertype"):get_dissector(35143)
The protocol gnw (GeoNetworking) corresponds to an EtherType of 35143 in my
Wireshark protocols configuration. However, this also fails to find the "gnw"
protocol.
How can I get wireshark to detect the GeoNetworking protocol from my custom Lua
script?
Thanks in advance.
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