-- b-CAP.lua
--
-- a basic Wireshark's LUA dissector for Binary Controller Access Protocol
-- see README for installation and usage
--
-- Copyright (C) 2014 DENSO WAVE INCORPORATED
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.

-- b-CAP definition
bCAP_proto = Proto("b-cap", "b-CAP", "Binary Controller Access Protocol")

-- function: main
function bCAP_proto.dissector(buffer, pinfo, tree)
	pinfo.cols.protocol = "b-CAP"	
	local subtree = tree:add(bCAP_proto, buffer(), "b-CAP Packet")
	
	if buffer(0, 1):uint() ~= 1 or buffer(buffer:len() - 1, 1):uint() ~= 4 then
		subtree:add(buffer(), "Error: Message length is too long")
		return
	end

	-- pinfo.port_type -> tcp: 2, udp: 3 (maybe)
	if buffer(buffer:len() - 2, 1):uint() == 1 then
		subtree:add(buffer(), "Error: This message compressed by ZIP")
		return
	end
	
	subtree:add(buffer(1, 4), "Message length: " .. buffer(1, 4):le_uint())
	subtree:add(buffer(5, 2), "Serial number: " .. buffer(5, 2):le_uint())
	subtree:add(buffer(7, 2), "Version or Retry: " .. buffer(7, 2):le_uint())
	subtree:add(buffer(9, 4), "Function ID or Return code: " .. buffer(9, 4):le_int())
	
	local num = buffer(13, 2):le_uint()
	subtree:add(buffer(13, 2), "Number of Args: " .. num)
	
	-- tvb -> Variant array
	tvb2VariantArray(subtree, buffer, 15, num, true)
end

-- load table of udp.port
udp_table = DissectorTable.get("udp.port")
udp_table:add(5007, bCAP_proto)

-- load table of tcp.port
tcp_table = DissectorTable.get("tcp.port")
tcp_table:add(5007, bCAP_proto)

-- function: tvb -> Variant arrray
function tvb2VariantArray(tree, buffer, offset, num, first)
	local tmp = offset

	for i = 0, (num - 1) do
		local subtree
		if first then
			subtree = tree:add(buffer(offset, buffer(offset, 4):le_int() + 4), "Arg" .. i)
			offset = offset + 4
		else
			subtree = tree:add("Arg" .. i)
		end
		
		-- Data type
		local type = buffer(offset, 2):le_int()
		subtree:add(buffer(offset, 2), "Data type: " .. DataType2String(type))
		offset = offset + 2
		
		-- The number of arrays
		local ary = buffer(offset, 4):le_uint()
		subtree:add(buffer(offset, 4), "The number of arrays: " .. ary)
		offset = offset + 4
		
		-- Variant
		offset = offset + tvb2Variant(subtree, buffer, offset, type, ary)
	end
	
	return offset - tmp
end

-- function: tvb -> Variant
function tvb2Variant(tree, buffer, offset, type, ary)
	local tmp = offset
	local str

	if type >= 0x2000 then
		type = type - 0x2000
		
		if type == 17 then -- UI1 | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 1):le_uint()
				else
					str = str .. ", " .. buffer(offset + i, 1):le_uint()
				end
			end
			tree:add(buffer(offset, ary), "Data: " .. str)
			offset = offset + ary
		elseif type == 2 then -- I2 | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 2):le_uint()
				else
					str = str .. ", " .. buffer(offset + 2 * i, 2):le_int()
				end
			end
			tree:add(buffer(offset, 2 * ary), "Data: " .. str)
			offset = offset + 2 * ary
		elseif type == 18 then -- UI2 | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 2):le_uint()
				else
					str = str .. ", " .. buffer(offset + 2 * i, 2):le_uint()
				end
			end
			tree:add(buffer(offset, 2 * ary), "Data: " .. str)
			offset = offset + 2 * ary
		elseif type == 3 then -- I4 | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 4):le_uint()
				else
					str = str .. ", " .. buffer(offset + 4 * i, 4):le_int()
				end
			end
			tree:add(buffer(offset, 4 * ary), "Data: " .. str)
			offset = offset + 4 * ary
		elseif type == 19 then -- UI4 | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 4):le_uint()
				else
					str = str .. ", " .. buffer(offset + 4 * i, 4):le_uint()
				end
			end
			tree:add(buffer(offset, 4 * ary), "Data: " .. str)
			offset = offset + 4 * ary
		elseif type == 4 then -- R4 | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 4):le_float()
				else
					str = str .. ", " .. buffer(offset + 4 * i, 4):le_float()
				end
			end
			tree:add(buffer(offset, 4 * ary), "Data: " .. str)
			offset = offset + 4 * ary
		elseif type == 5 then -- R8 | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 8):le_float()
				else
					str = str .. ", " .. buffer(offset + 8 * i, 8):le_float()
				end
			end
			tree:add(buffer(offset, 8 * ary), "Data: " .. str)
			offset = offset + 8 * ary
		elseif type == 6 then -- CY | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 8):le_int64()
				else
					str = str .. ", " .. buffer(offset + 8 * i, 8):le_int64()
				end
			end
			tree:add(buffer(offset, 8 * ary), "Data: " .. str)
			offset = offset + 8 * ary
		elseif type == 7 then -- DATE | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					str = buffer(offset, 8):le_float()
				else
					str = str .. ", " .. buffer(offset + 8 * i, 8):le_float()
				end
			end
			tree:add(buffer(offset, 8 * ary), "Data: " .. str)
			offset = offset + 8 * ary
		elseif type == 11 then -- BOOL | ARRAY
			for i = 0, (ary - 1) do
				if i == 0 then
					if buffer(offset, 2):le_int() == 0 then
						str = "False"
					else
						str = "True"
					end
				else
					if buffer(offset + 2 * i, 2):le_int() == 0 then
						str = str .. ", False"
					else
						str = str .. ", True"
					end
				end
			end
			tree:add(buffer(offset, 2 * ary), "Data: " .. str)
			offset = offset + 2 * ary
		elseif type == 8 then -- BSTR | ARRAY
			local len, mem
			mem = offset
			for i = 0, (ary - 1) do
				len = buffer(offset, 4):le_uint()
				if i == 0 then
					if len > 0 then
						str = buffer(offset + 4, len):le_ustring()
					else
						str = ""
					end
				else
					str = str .. ", "
					if len > 0 then
						str = str .. buffer(offset + 4, len):le_ustring()
					end
				end
				offset = offset + 4 + len
			end
			tree:add(buffer(mem, offset - mem), "Data: " .. str)
		elseif type == 12 then -- VARIANT | ARRAY
			local len = tvb2VariantArray(tree, buffer, offset, ary, false)
			offset = offset + len
		end
	else
		if type == 10 then -- ERROR
			str = buffer(offset, 4):le_int()
			tree:add(buffer(offset, 4), "Data: " .. str)
			offset = offset + 4
		elseif type == 17 then -- UI1
			str = buffer(offset, 1):le_uint()
			tree:add(buffer(offset, 1), "Data: " .. str)
			offset = offset + 1
		elseif type == 2 then -- I2
			str = buffer(offset, 2):le_int()
			tree:add(buffer(offset, 2), "Data: " .. str)
			offset = offset + 2
		elseif type == 18 then -- UI2
			str = buffer(offset, 2):le_uint()
			tree:add(buffer(offset, 2), "Data: " .. str)
			offset = offset + 2
		elseif type == 3 then -- I4
			str = buffer(offset, 4):le_int()
			tree:add(buffer(offset, 4), "Data: " .. str)
			offset = offset + 4
		elseif type == 19 then -- UI4
			str = buffer(offset, 4):le_uint()
			tree:add(buffer(offset, 4), "Data: " .. str)
			offset = offset + 4
		elseif type == 4 then -- R4
			str = buffer(offset, 4):le_float()
			tree:add(buffer(offset, 4), "Data: " .. str)
			offset = offset + 4
		elseif type == 5 then -- R8
			str = buffer(offset, 8):le_float()
			tree:add(buffer(offset, 8), "Data: " .. str)
			offset = offset + 8
		elseif type == 6 then -- CY
			str = buffer(offset, 8):le_int64()
			tree:add(buffer(offset, 8), "Data: " .. str)
			offset = offset + 8
		elseif type == 7 then -- DATE
			str = buffer(offset, 8):le_float()
			tree:add(buffer(offset, 8), "Data: " .. str)
			offset = offset + 8
		elseif type == 11 then -- BOOL
			if buffer(offset, 2):le_int() == 0 then
				str = "False"
			else
				str = "True"
			end
			tree:add(buffer(offset, 2), "Data: " .. str)
			offset = offset + 2
		elseif type == 8 then -- BSTR
			local len = buffer(offset, 4):le_uint()
			if len > 0 then
				str = buffer(offset + 4, len):le_ustring()
			else
				str = ""
			end
			tree:add(buffer(offset, 4 + len), "Data: " .. str)
			offset = offset + 4 + len
		end
	end
	
	return offset - tmp
end

-- Data type string
function DataType2String(type)
	local strReturn = ""
	
	if type >= 0x2000 then
		strReturn = "VT_ARRAY | "
		type = type - 0x2000
	end
	
	if type == 0 then
		strReturn = strReturn .. "VT_EMPTY"
	elseif type == 1 then
		strReturn = strReturn .. "VT_NULL"
	elseif type == 10 then
		strReturn = strReturn .. "VT_ERROR"
	elseif type == 17 then
		strReturn = strReturn .. "VT_UI1"
	elseif type == 2 then
		strReturn = strReturn .. "VT_I2"
	elseif type == 18 then
		strReturn = strReturn .. "VT_UI2"
	elseif type == 3 then
		strReturn = strReturn .. "VT_I4"
	elseif type == 19 then
		strReturn = strReturn .. "VT_UI4"
	elseif type == 4 then
		strReturn = strReturn .. "VT_R4"
	elseif type == 5 then
		strReturn = strReturn .. "VT_R8"
	elseif type == 6 then
		strReturn = strReturn .. "VT_CY"
	elseif type == 7 then
		strReturn = strReturn .. "VT_DATE"
	elseif type == 11 then
		strReturn = strReturn .. "VT_BOOL"
	elseif type == 8 then
		strReturn = strReturn .. "VT_BSTR"
	elseif type == 12 then
		strReturn = strReturn .. "VT_VARIANT"
	end
	
	return strReturn
end