trivial-retbytes.lua

-- trivial protocol example
-- inspired by http://wiki.wireshark.org/Lua/Dissectors

-- declare our protocol
trivial_proto = Proto("trivial","Trivial Protocol")
-- create a function to dissect it
function trivial_proto.dissector(buffer,pinfo,tree)	
	local trivial_pdu_len = 4
	
	pinfo.cols.protocol = "TRIVIAL"
	local subtree = tree:add(trivial_proto,buffer(),"Trivial Protocol Data")
	subtree:add(buffer(0,2),"The first two bytes: " .. buffer(0,2):uint())
	subtree = subtree:add(buffer(2,2),"The next two bytes")
	subtree:add(buffer(2,1),"The 3rd byte: " .. buffer(2,1):uint())
	subtree:add(buffer(3,1),"The 4th byte: " .. buffer(3,1):uint())
	
	-- return number of bytes consumed so that more trivial PDUs can be discovered
	return trivial_pdu_len

end

-- load the tcp.port table
tcp_table = DissectorTable.get("tcp.port")
-- register our protocol to handle udp port 7777
tcp_table:add(7777,trivial_proto)