crtp-dissector.lua

-- declare our protocol
crtp = Proto("CrazyRealTimeTProtocol", "Crazy Real Time Protocol")

-- General CRTP packet fields
local f_crtp_port = ProtoField.uint8("crtp.port", "Port")
local f_crtp_channel = ProtoField.uint8("crtp.channel", "Channel")
local f_crtp_size = ProtoField.uint8("crtp.size", "Size")
local f_crtp_undecoded = ProtoField.string("crtp.undecoded", "Undecoded")

-- Specialized CRTP service fields
local f_crtp_console_text = ProtoField.string("crtp.console_text", "Text", base.ASCII)
local f_crtp_parameter_varid = ProtoField.uint16("crtp.parameter_varid", "Variable Id")
local f_crtp_parameter_type = ProtoField.string("crtp.parameter_type", "Parameter Type")
local f_crtp_parameter_group = ProtoField.string("crtp.parameter_group", "Parameter Group")
local f_crtp_parameter_name = ProtoField.string("crtp.parameter_name", "Parameter Name")
local f_crtp_parameter_count = ProtoField.uint16("crtp.parameter_count", "Parameter Count")
local f_crtp_parameter_crc = ProtoField.string("crtp.parameter_crc", "Parameter CRC")
local f_crtp_parameter_val_uint = ProtoField.uint32("crtp.parameter_val_uint", "Value uint")
local f_crtp_parameter_val_int = ProtoField.int32("crtp.parameter_val_int", "Value int")
local f_crtp_parameter_val_float = ProtoField.float("crtp.parameter_val_float", "Value float")

local f_crtp_log_varid = ProtoField.uint16("crtp.log_varid", "Variable Id")
local f_crtp_log_type = ProtoField.string("crtp.log_type", "Log Type")
local f_crtp_log_group = ProtoField.string("crtp.log_group", "Log Group")
local f_crtp_log_name = ProtoField.string("crtp.log_name", "Log Name")
local f_crtp_log_count = ProtoField.uint16("crtp.log_count", "Log Count")
local f_crtp_log_crc = ProtoField.string("crtp.log_crc", "Log CRC")

local f_crtp_setpoint_hl_command = ProtoField.string("crtp.setpoint_hl_command", "Command")
local f_crtp_setpoint_hl_retval = ProtoField.uint8("crtp.setpoint_hl_retval", "Return Value")

local f_crtp_setpoint_hl_groupmask = ProtoField.uint8("crtp.setpoint_hl_groupmask", "Group Mask")
local f_crtp_setpoint_hl_id = ProtoField.uint8("crtp.setpoint_hl_id", "Trajectory Id")

local f_crtp_setpoint_hl_height = ProtoField.float("crtp.setpoint_hl_height", "Height")
local f_crtp_setpoint_hl_yaw = ProtoField.float("crtp.setpoint_hl_yaw", "Yaw")
local f_crtp_setpoint_hl_use_yaw = ProtoField.bool("crtp.setpoint_hl_use_yaw", "Use Current Yaw")
local f_crtp_setpoint_hl_relative = ProtoField.bool("crtp.setpoint_hl_relative", "Relative")
local f_crtp_setpoint_hl_duration = ProtoField.float("crtp.setpoint_hl_duration", "Duration")
local f_crtp_setpoint_hl_timescale = ProtoField.float("crtp.setpoint_hl_timescale", "Timescale")

local f_crtp_setpoint_hl_x = ProtoField.float("crtp.setpoint_hl_x", "X")
local f_crtp_setpoint_hl_y = ProtoField.float("crtp.setpoint_hl_y", "Y")
local f_crtp_setpoint_hl_z = ProtoField.float("crtp.setpoint_hl_z", "Z")

local f_crtp_echo_data = ProtoField.uint32("crtp.echo_data", "Echo Data")

-- All possible fields registred
crtp.fields = {
	f_crtp_port,
	f_crtp_channel,
	f_crtp_console_text,
	f_crtp_size,
	f_crtp_parameter_varid,
	f_crtp_parameter_val_uint,
	f_crtp_parameter_val_int,
	f_crtp_parameter_val_float,
	f_crtp_parameter_name,
	f_crtp_parameter_group,
	f_crtp_parameter_type,
	f_crtp_parameter_count,
	f_crtp_parameter_crc,
	f_crtp_log_varid,
	f_crtp_log_name,
	f_crtp_log_group,
	f_crtp_log_type,
	f_crtp_log_count,
	f_crtp_log_crc,
	f_crtp_setpoint_hl_command,
	f_crtp_setpoint_hl_retval,
	f_crtp_setpoint_hl_use_yaw,
	f_crtp_setpoint_hl_yaw,
	f_crtp_setpoint_hl_groupmask,
	f_crtp_setpoint_hl_duration,
	f_crtp_setpoint_hl_height,
	f_crtp_setpoint_hl_relative,
	f_crtp_setpoint_hl_x,
	f_crtp_setpoint_hl_y,
	f_crtp_setpoint_hl_z,
	f_crtp_setpoint_hl_id,
	f_crtp_setpoint_hl_timescale,
	f_crtp_echo_data,
	f_crtp_undecoded,
}

local param_toc = {}
local log_toc = {}

local Links = {
	UNKNOWN = 0,
	RADIO = 1,
	USB = 2,
}

local link = Links.UNKNOWN
local undecoded = 0
local crtp_start = 0

-- Analye port and channel and figure what service (port name / channel name)
-- we are dealing with

local Ports = {
	Console = 0x0,
	Parameters = 0x2,
	Commander = 0x3,
	Memory = 0x4,
	Logging = 0x5,
	Localization = 0x6,
	Commander_Generic = 0x7,
	Setpoint_Highlevel = 0x8,
	Platform = 0xD,
	LinkControl = 0xF,
	ALL = 0xFF
}

function get_crtp_port_channel_names(port, channel)
	local port_name = "Unknown"
	local channel_name = nil

	if port == Ports.Console and channel == 0 then
		port_name = "Console"
	elseif port == 0x02 then
		port_name = "Parameters"
		if channel == 0 then
			channel_name = "Table Of Contents"
		elseif channel == 1 then
			channel_name = "Read"
		elseif channel == 2 then
			channel_name = "Write"
		elseif channel == 3 then
			channel_name = "Misc"
		end
	elseif port == 0x03 then
		port_name = "Commander"
	elseif port == 0x04 then
		port_name = "Memory"
		if channel == 0 then
			channel_name = "Information"
		elseif channel == 1 then
			channel_name = "Read"
		elseif channel == 2 then
			channel_name = "Write"
		end
	elseif port == 0x05 then
		port_name = "Logging"
		if channel == 0 then
			channel_name = "Table Of Contents"
		elseif channel == 1 then
			channel_name = "Settings"
		elseif channel == 2 then
			channel_name = "Log data"
		end
	elseif port == 0x06 then
		port_name = "Localization"
		if channel == 0 then
			channel_name = "Position"
		elseif channel == 1 then
			channel_name = "Generic"
		end
	elseif port == 0x07 then
		port_name = "Commander Generic"
	elseif port == 0x08 then
		port_name = "Setpoint Highlevel"
	elseif port == 0x0D then
		port_name = "Platform"
		if channel == 0 then
			channel_name = "Platform Command"
		elseif channel == 1 then
			channel_name = "Version Command"
		elseif channel == 2 then
			channel_name = "App Layer"
		end
	elseif port == 0x0F then
		port_name = "Link Control"
		if channel == 0 then
			channel_name = "Echo"
		elseif channel == 1 then
			channel_name = "Link Service Source"
		end
	elseif port == 0xFF then
		port_name = "ALL"
	end

	return port_name, channel_name
end

function format_address(buffer)
	if link == Links.RADIO then
		addr = buffer(2, 5):bytes():tohex()
		port = buffer(7, 1):uint()

		addr = addr:gsub("..", ":%0"):sub(2)
		port = tostring(port)

		return addr .. " (" .. port .. ")"
	elseif link == Links.USB then
		return buffer(2, 12):bytes():tohex()
	end
end

function format_device(buffer)
	if link == Links.RADIO then
		devid = buffer(8, 1):uint()
		return "Radio #" .. tostring(devid)
	elseif link == Links.USB then
		devid = buffer(15, 1):uint()
		return "USB #" .. tostring(devid)
	end
end

function handle_setpoint_highlevel(tree, receive, buffer, channel, size)
	local Commands = {
		COMMAND_SET_GROUP_MASK = 0,
		COMMAND_TAKEOFF = 1,
		COMMAND_LAND = 2,
		COMMAND_STOP = 3,
		COMMAND_GO_TO = 4,
		COMMAND_START_TRAJECTORY = 5,
		COMMAND_DEFINE_TRAJECTORY = 6,
		COMMAND_TAKEOFF_2 = 7,
		COMMAND_LAND_2 = 8,
		COMMAND_TAKEOFF_WITH_VELOCITY = 9,
		COMMAND_LAND_WITH_VELOCITY = 10,
	}

	local height = nil
	local duration = nil
	local yaw = nil
	local group_mask = nil
	local use_yaw = nil
	local relative = nil
	local x = nil
	local y = nil
	local z = nil
	local id = nil
	local timescale = nil

	local port_tree = tree:add(crtp, port_name)

	local cmd = buffer(crtp_start + 1, 1):uint()
	local cmd_str = "Unknown"

	if cmd == Commands.COMMAND_SET_GROUP_MASK then
		cmd_str = "Set Group Mask"

		-- struct data_set_group_mask {
		--    uint8_t groupMask;        // mask for which CFs this should apply to
		--  } __attribute__((packed));
		if receive == 0 then
			group_mask = buffer(11, 1):uint()
		end
	elseif cmd == Commands.COMMAND_TAKEOFF then
		cmd_str = "Take Off (deprecated)"
	elseif cmd == Commands.COMMAND_LAND then
		cmd_str = "Land (deprecated)"
	elseif cmd == Commands.COMMAND_STOP then
		cmd_str = "Stop"

		-- struct data_stop {
		--    uint8_t groupMask;        // mask for which CFs this should apply to
		--  } __attribute__((packed));
		if receive == 0 then
			group_mask = buffer(crtp_start + 2, 1):uint()
		end
		undecoded = undecoded - 1
	elseif cmd == Commands.COMMAND_GO_TO then
		cmd_str = "Go To"

		-- struct data_go_to {
		--    uint8_t groupMask; // mask for which CFs this should apply to
		--    uint8_t relative;  // set to true, if position/yaw are relative to current setpoint
		--    float x; // m
		--    float y; // m
		--    float z; // m
		--    float yaw; // rad
		--    float duration; // sec
		--  } __attribute__((packed));
		if receive == 0 then
			group_mask = buffer(crtp_start + 2, 1):uint()
			relative = buffer(crtp_start + 3, 1):uint()
			x = buffer(crtp_start + 4, 4):le_float()
			y = buffer(crtp_start + 8, 4):le_float()
			z = buffer(crtp_start + 12, 4):le_float()
			yaw = buffer(crtp_start + 16, 4):le_float()
			duration = buffer(crtp_start + 20, 4):le_float()
			undecoded = undecoded - 24
		end
	elseif cmd == Commands.COMMAND_START_TRAJECTORY then
		cmd_str = "Start Trajectory"

		-- struct data_start_trajectory {
		--   uint8_t groupMask; // mask for which CFs this should apply to
		--   uint8_t relative;  // set to true, if trajectory should be shifted to current setpoint
		--   uint8_t reversed;  // set to true, if trajectory should be executed in reverse
		--   uint8_t trajectoryId; // id of the trajectory (previously defined by COMMAND_DEFINE_TRAJECTORY)
		--   float timescale; // time factor; 1 = original speed; >1: slower; <1: faster
		--  } __attribute__((packed));
		if receive == 0 then
			group_mask = buffer(crtp_start + 2, 1):uint()
			relative = buffer(crtp_start + 3, 1):uint()
			reversed = buffer(crtp_start + 4, 1):uint()
			id = buffer(crtp_start + 5, 1):uint()
			timescale = buffer(crtp_start + 6):float()
			undecoded = undecoded - 10
		end
	elseif cmd == Commands.COMMAND_DEFINE_TRAJECTORY then
		cmd_str = "Define Trajectory"

		-- struct data_define_trajectory {
		--    uint8_t trajectoryId;
		--    struct trajectoryDescription description;
		--  } __attribute__((packed));
		if receive == 0 then
			id = buffer(crtp_start + 2, 1):uint()
			undecoded = undecoded - 1
		end
	elseif cmd == Commands.COMMAND_TAKEOFF_2 then
		cmd_str = "Take Off"

		-- struct data_takeoff_2 {
		-- uint8_t groupMask;        // mask for which CFs this should apply to
		-- float height;             // m (absolute)
		-- float yaw;                // rad
		-- bool useCurrentYaw;       // If true, use the current yaw (ignore the yaw parameter)
		-- float duration;           // s (time it should take until target height is reached)
		-- } __attribute__((packed));
		if receive == 0 then
			group_mask = buffer(crtp_start + 2, 1):uint()
			height = buffer(crtp_start + 3, 4):le_float()
			yaw = buffer(crtp_start + 7, 4):le_float()
			use_yaw = buffer(crtp_start + 11, 1):uint()
			duration = buffer(crtp_start + 12, 4):le_float()
			undecoded = undecoded - 16
		end
	elseif cmd == Commands.COMMAND_LAND_2 then
		cmd_str = "Land"
		-- struct data_land_2 {
		-- uint8_t groupMask;        // mask for which CFs this should apply to
		-- float height;             // m (absolute)
		-- float yaw;                // rad
		-- bool useCurrentYaw;       // If true, use the current yaw (ignore the yaw parameter)
		-- float duration;           // s (time it should take until target height is reached)
		-- } __attribute__((packed));
		if receive == 0 then
			group_mask = buffer(crtp_start + 2, 1):uint()
			height = buffer(crtp_start + 3, 4):le_float()
			yaw = buffer(crtp_start + 7, 4):le_float()
			use_yaw = buffer(crtp_start + 11, 1):uint()
			duration = buffer(crtp_start + 12, 4):le_float()
			undecoded = undecoded - 16
		end
	elseif cmd == Commands.COMMAND_TAKEOFF_WITH_VELOCITY then
		cmd_str = "Take Off With Velocity"
	elseif cmd == Commands.COMMAND_LAND_WITH_VELOCITY then
		cmd_str = "Land With Velocity"
	end

	port_tree:add_le(f_crtp_setpoint_hl_command, cmd_str)
	local success = true
	if receive == 1 then
		retval = buffer(crtp_start + 4):uint()
		local success = (retval == 0) and "Success" or "Failure"
		port_tree:add_le(f_crtp_setpoint_hl_retval, retval):append_text(" (" .. success .. ")")
		undecoded = undecoded - 4
	end

	if id then
		port_tree:add_le(f_crtp_setpoint_hl_id, id)
	end
	if timescale then
		port_tree:add_le(f_crtp_setpoint_hl_timescale, timescale)
	end
	if group_mask then
		port_tree:add_le(f_crtp_setpoint_hl_groupmask, group_mask)
	end
	if relative then
		port_tree:add_le(f_crtp_setpoint_hl_relative, relative)
	end
	if height then
		port_tree:add_le(f_crtp_setpoint_hl_height, height):append_text(" (m)")
	end
	if x then
		port_tree:add_le(f_crtp_setpoint_hl_x, x)
	end
	if y then
		port_tree:add_le(f_crtp_setpoint_hl_y, y)
	end
	if z then
		port_tree:add_le(f_crtp_setpoint_hl_z, z)
	end
	if yaw then
		port_tree:add_le(f_crtp_setpoint_hl_yaw, yaw)
	end
	if use_yaw then
		port_tree:add_le(f_crtp_setpoint_hl_use_yaw, use_yaw)
	end
	if duration then
		port_tree:add_le(f_crtp_setpoint_hl_duration, duration):append_text(" (s)")
	end
end

function append_param_type(str, type)
	if #str == 0 then
		return type
	else
		return str .. " | " .. type
	end
end

function get_log_types(byte)
	type = ""

	local core = 0x20
	local byfunc = 0x40
	local group = 0x80

	num_types_map = {
		"LOG_UINT8",
		"LOG_UINT16",
		"LOG_UINT32",
		"LOG_INT8",
		"LOG_INT16",
		"LOG_INT32",
		"LOG_FLOAT",
		"LOG_FP16",
	}

	num_type = bit.band(byte, 0x0F)
	type = num_types_map[num_type]

	if bit.band(byte, core) ~= 0 then
		type = append_param_type(type, "LOG_CORE")
	end

	if bit.band(byte, byfunc) ~= 0 then
		type = append_param_type(type, "LOG_BYFUNC")
	end

	if bit.band(byte, group) ~= 0 then
		type = append_param_type(type, "LOG_GROUP")
	end

	return byte .. " (" .. type .. ")"
end

function get_param_types(byte)
	type = ""

	local ext = bit.lshift(1, 4)
	local core = bit.lshift(1, 5)
	local ronly = bit.lshift(1, 6)
	local group = bit.lshift(1, 7)

	num_type = bit.band(byte, 0x0F)
	if num_type == 0 then
		type = "PARAM_INT8"
	elseif num_type == bit.lshift(0x1, 3) then
		type = "PARAM_UINT8"
	elseif num_type == bit.bor(0x1, bit.lshift(0x1, 3)) then
		type = "PARAM_UINT16"
	elseif num_type == 0x1 then
		type = "PARAM_INT16"
	elseif num_type == 0x2 then
		type = "PARAM_INT32"
	elseif num_type == bit.bor(0x2, bit.lshift(0x1, 3)) then
		type = "PARAM_UINT32"
	elseif num_type == bit.bor(0x2, bit.lshift(0x1, 2)) then
		type = "PARAM_FLOAT"
	end

	if bit.band(byte, core) ~= 0 then
		type = append_param_type(type, "PARAM_CORE")
	end

	if bit.band(byte, ronly) ~= 0 then
		type = append_param_type(type, "PARAM_RONLY")
	end

	if bit.band(byte, group) ~= 0 then
		type = append_param_type(type, "PARAM_GROUP")
	end

	if bit.band(byte, ext) ~= 0 then
		type = append_param_type(type, "PARAM_EXTENDED")
	end

	return byte .. " (" .. type .. ")"
end

function handle_logging_port(tree, receive, buffer, channel, size)
	local port_tree = tree:add(crtp, port_name)

	-- TOC
	if channel == 0 then
		message_id = buffer(crtp_start + 1, 1):le_uint()
		if message_id == 3 and receive == 1 then
			port_tree:add_le(f_crtp_log_count, buffer(crtp_start + 2, 2):le_uint())
			port_tree:add_le(f_crtp_log_crc, buffer(crtp_start + 4):bytes():tohex())
		end
		if message_id == 2 then
			-- GET_ITEM
			item = {}
			item["varid"] = buffer(crtp_start + 2, 2):le_uint()
			port_tree:add_le(f_crtp_log_varid, item["varid"])

			if receive == 1 then
				item["type"] = get_log_types(buffer(crtp_start + 4, 1):le_uint())
				item["group"] = ""
				item["name"] = ""
				full_name = buffer(crtp_start + 5):string()

				stored_group = false
				for i = 1, #full_name do
					local c = full_name:sub(i, i)
					if string.byte(c) == 0 and not stored_group then
						stored_group = true
					else
						if stored_group then
							item["name"] = item["name"] .. c
						else
							item["group"] = item["group"] .. c
						end
					end
				end

				log_toc[item["varid"]] = item
				port_tree:add_le(f_crtp_log_type, item["type"])
				port_tree:add_le(f_crtp_log_group, item["group"])
				port_tree:add_le(f_crtp_log_name, item["name"])
			end
		end
	end
end

function handle_parameter_port(tree, receive, buffer, channel, size)
	local port_tree = tree:add(crtp, port_name)

	-- Read or Write
	if (channel == 1 or channel == 2) and size > 2 then
		if channel == 1 then
			value_start = 4
		else
			value_start = 3
		end

		-- Add variable id
		local var_id = buffer(crtp_start + 1, 2):le_uint()
		port_tree:add_le(f_crtp_parameter_varid, var_id)

		item = param_toc[var_id]
		port_tree:add_le(f_crtp_parameter_group, item["group"])
		port_tree:add_le(f_crtp_parameter_name, item["name"])

		-- Add value
		if size > 3 then
			port_tree:add_le(f_crtp_parameter_val_uint, buffer(crtp_start + value_start):le_uint())
			port_tree:add_le(f_crtp_parameter_val_int, buffer(crtp_start + value_start):le_int())
		end
		if size >= 7 then
			port_tree:add_le(f_crtp_parameter_val_float, buffer(crtp_start + value_start):le_float())
		end
		undecoded = 0
	end
	-- TOC
	if channel == 0 then
		message_id = buffer(crtp_start + 1, 1):le_uint()
		if message_id == 3 and receive == 1 then
			port_tree:add_le(f_crtp_parameter_count, buffer(crtp_start + 2, 2):le_uint())
			port_tree:add_le(f_crtp_parameter_crc, buffer(crtp_start + 4):bytes():tohex())
		end
		if message_id == 2 then
			-- GET_ITEM
			item = {}
			item["varid"] = buffer(crtp_start + 2, 2):le_uint()
			port_tree:add_le(f_crtp_parameter_varid, item["varid"])

			if receive == 1 then
				item["type"] = get_param_types(buffer(crtp_start + 4, 1):le_uint())
				item["group"] = ""
				item["name"] = ""
				full_name = buffer(crtp_start + 5):string()

				stored_group = false
				for i = 1, #full_name do
					local c = full_name:sub(i, i)
					if string.byte(c) == 0 and not stored_group then
						stored_group = true
					else
						if stored_group then
							item["name"] = item["name"] .. c
						else
							item["group"] = item["group"] .. c
						end
					end
				end

				param_toc[item["varid"]] = item
				port_tree:add_le(f_crtp_parameter_type, item["type"])
				port_tree:add_le(f_crtp_parameter_group, item["group"])
				port_tree:add_le(f_crtp_parameter_name, item["name"])
			end
		end
	end
end

-- create a function to dissect it, layout:
-- | link_type | receive| address       | channel | radio devid | crtp header | crtp data |
-- | 1 byte    | 1 byte | 5 or 12 bytes |  1 byte |    1 byte   |    1 byte   |   n bytes |
function crtp.dissector(buffer, pinfo, tree)
	pinfo.cols.protocol = "CRTP"

	link = buffer(0, 1):uint()
	if link == Links.RADIO then
		crtp_start = 9
	elseif link == Links.USB then
		crtp_start = 16
	end

	if buffer:len() <= crtp_start then
		return
	end

	local receive = buffer(1, 1):uint()
	if receive == 1 then
		pinfo.cols.dst = format_device(buffer)
		pinfo.cols.src = format_address(buffer)
	else
		pinfo.cols.dst = format_address(buffer)
		pinfo.cols.src = format_device(buffer)
	end

	local subtree = tree:add(crtp, "CRTP Packet")
	local header = bit.band(buffer(crtp_start, 1):uint(), 0xF3)
	local crtp_port = bit.rshift(bit.band(header, 0xF0), 4)
	local crtp_channel = bit.band(header, 0x03)

	-- Add CRTP packet size:
	-- receive_byte + address + channel + devid = 8
	-- Rest is CRTP packet
	local crtp_size = buffer:len() - crtp_start
	subtree:add_le(f_crtp_size, crtp_size)

	undecoded = crtp_size - 1

	-- Check for safelink packet
	if crtp_size == 3 and header == 0xF3 and buffer(crtp_start + 1, 1):uint() == 0x05 then
		pinfo.cols.info = "SafeLink"
		return
	end

	-- Get port and channel name
	port_name, channel_name = get_crtp_port_channel_names(crtp_port, crtp_channel)

	-- Display port in info column
	pinfo.cols.info = port_name

	-- Add to CRTP tree
	subtree:add_le(f_crtp_port, crtp_port):append_text(" (" .. port_name .. ")")
	if channel_name then
		subtree:add_le(f_crtp_channel, crtp_channel):append_text(" (" .. channel_name .. ")")
	else
		subtree:add_le(f_crtp_channel, crtp_channel)
	end

	-- Check for special handling

	-- Console, we can add text
	if crtp_port == Ports.Console then
		local port_tree = tree:add(crtp, port_name)
		port_tree:add_le(f_crtp_console_text, buffer(crtp_start + 1):string())
		undecoded = 0
	end

	if crtp_port == Ports.LinkControl then
		if crtp_channel == 0 then -- Echo
			local port_tree = tree:add(crtp, channel_name)
			port_tree:add_le(f_crtp_echo_data, buffer(crtp_start + 1):le_uint())
			undecoded = 0
		end
	end

	if crtp_port == Ports.Parameters then
		handle_parameter_port(tree, receive, buffer, crtp_channel, crtp_size)
	end

	if crtp_port == Ports.Logging then
		handle_logging_port(tree, receive, buffer, crtp_channel, crtp_size)
	end

	if crtp_port == Ports.Setpoint_Highlevel then
		handle_setpoint_highlevel(tree, receive, buffer, crtp_channel, crtp_size)
	end

	if undecoded > 0 then
		local from = crtp_start + (crtp_size - undecoded)
		subtree:add_le(f_crtp_undecoded, buffer(from, undecoded):bytes():tohex())
	end
end

wtap_encap = DissectorTable.get("wtap_encap")
wtap_encap:add(wtap.USER15, crtp)