exo_sw_dissectors/Dissector/ftci_dissector.lua

function ftci_dissector(buffer, pinfo, tree, FTCI_protocol, offset)

    -- Define ProtoFields for each of the fields in the structure

    -- Control Field 1 (1 byte)
    local f_session_id = ProtoField.uint8("FileTransfer.session_id", "File Transfer Session ID", base.DEC)
    local f_resume_context_mode = ProtoField.uint8("FileTransfer.resume_context_mode", "Resume Context Mode", base.DEC)
    local f_seq_loss_detection_mode = ProtoField.string("FileTransfer.seq_loss_detection_mode", "Seq Loss Detection Mode")
    local f_file_id = ProtoField.uint8("FileTransfer.file_id", "File ID", base.DEC)
 

    -- Control Field 2 (1 byte)
    local f_transfer_mode = ProtoField.uint8("FileTransfer.transfer_mode", "Transfer Mode (TXM)", base.DEC)
    local f_file_format = ProtoField.uint8("FileTransfer.file_format", "File Format", base.HEX)
    local f_unit_size = ProtoField.uint8("FileTransfer.unit_size", "Unit Size", base.DEC)
    local f_size_field_type = ProtoField.uint8("FileTransfer.size_field_type", "Size Field Type", base.HEX)

    -- Other fields
    local f_checksum = ProtoField.uint32("FileTransfer.checksum", "Checksum",base.HEX)
    local f_mtu_size = ProtoField.uint16("FileTransfer.mtu_size", "MTU Size", base.DEC)
    local f_rx_con_fail_timeout = ProtoField.uint16("FileTransfer.rx_con_fail_timeout", "Receiver Connection Fail Timeout", base.DEC)
    local f_major_version = ProtoField.uint8("FileTransfer.major_version", "Major Version", base.DEC)
    local f_minor_version = ProtoField.uint8("FileTransfer.minor_version", "Minor Version", base.DEC)
    local f_sct_instance_key = ProtoField.uint32("FileTransfer.sct_instance_key", "SCT Instance Key", base.DEC)
    local f_file_mem_size = ProtoField.bytes("FileTransfer.file_mem_size", "File/Mem Size")
    local f_dest_storage = ProtoField.uint8("FileTransfer.dest_storage", "Destination Storage", base.DEC)
    local f_dest_mem_address = ProtoField.uint32("FileTransfer.dest_mem_address", "Destination Memory Address", base.HEX)
    local f_file_path_len = ProtoField.uint8("FileTransfer.file_path_len", "File /Name Length", base.DEC)
    local f_file_path = ProtoField.string("FileTransfer.file_path", "File /Name")

    -- Add fields to protocol
    FTCI_protocol.fields = {
        f_session_id, f_resume_context_mode, f_seq_loss_detection_mode, f_file_id,
        f_transfer_mode, f_file_format, f_unit_size, f_size_field_type,
        f_checksum, f_mtu_size, f_rx_con_fail_timeout, f_major_version, f_minor_version, 
        f_sct_instance_key, f_file_mem_size, f_dest_storage, f_dest_mem_address, 
        f_file_path_len, f_file_path
    }

    -- Loop through the data instances
   -- for i = 1, num_of_instance do
        -- Add the new structure data as a subtree
        local subtree = tree:add( FTCI_protocol, buffer(), "FTCI")

        -- dissect CONTROL FIELD 1 (1 byte)
	local w=0
        local control_field1 = buffer(offset, 1):le_uint()
        local session_id = control_field1 & 0x07
        local resume_context_mode = (control_field1 >>3) & 0x01
        local seq_loss_detection_mode = (control_field1 >> 4) & 0x01
        local file_id = (control_field1 >>5) & 0x07
        subtree:add(f_session_id, session_id)
        subtree:add(f_resume_context_mode, resume_context_mode)
	if seq_loss_detection_mode == 0 then
        	subtree:add(f_seq_loss_detection_mode, "UNACK")
	else
		subtree:add(f_seq_loss_detection_mode, "ACK")
	end
        subtree:add(f_file_id, file_id)
        offset = offset + 1

        -- dissect CONTROL FIELD 2 (1 byte)
        local control_field2 = buffer(offset, 1):le_uint()
        local transfer_mode = (control_field2 >>0) & 0x01 --txm
        local file_format = (control_field2 >>1) & 0x07
        local unit_size = (control_field2 >>4) & 0x03
        local size_field_type = (control_field2 >>6) & 0x03
	if size_field_type == 0x01 then
		w=0
	elseif size_field_type == 0x02 then
		w=1
	elseif size_field_type > 0x02 then
		w=2
	end
        subtree:add(f_transfer_mode, transfer_mode)
        subtree:add(f_file_format, file_format)
        subtree:add(f_unit_size, unit_size)
        subtree:add(f_size_field_type, size_field_type)
        
	offset = offset + 1
	-- dissect MTU Size (2 bytes)
        local mtu_size = buffer(offset, 2):le_uint()
        subtree:add(f_mtu_size, mtu_size)
        offset = offset + 2

        -- dissect Checksum (4 bytes)
        local checksum = buffer(offset, 4):le_uint()
        subtree:add(f_checksum, checksum)
        offset = offset + 4

        

        -- dissect RX Connection Fail Timeout (2 bytes)
        local rx_con_fail_timeout = buffer(offset, 2):le_uint()
        subtree:add(f_rx_con_fail_timeout, rx_con_fail_timeout)
        offset = offset + 2

        -- dissect Major Version (1 byte)
        local major_version = buffer(offset, 1):le_uint()
        subtree:add(f_major_version, major_version)
        offset = offset + 1

        -- dissect Minor Version (1 byte)
        local minor_version = buffer(offset, 1):le_uint()
        subtree:add(f_minor_version, minor_version)
        offset = offset + 1

        -- dissect SCT Instance Key (4 bytes)
        local sct_instance_key = buffer(offset, 4):le_uint()
        subtree:add(f_sct_instance_key, sct_instance_key)
        offset = offset + 4

        -- dissect File/Mem Size (1-5 bytes, variable size)
	--if unit_size then
        	local file_mem_size_len = unit_size
        	local file_mem_size = buffer(offset , file_mem_size_len)
        	subtree:add(f_file_mem_size, file_mem_size)
        	offset = offset + file_mem_size_len
	--end

        -- dissect Destination Storage (1 byte)
	if transfer_mode == 0x01 then
        	local dest_storage = buffer(offset, 1):le_uint()
        	subtree:add(f_dest_storage, dest_storage)
        	offset = offset + 1
	
        	-- dissect Destination Memory Address (4 bytes)
        	local dest_mem_address = buffer(offset, 4):le_uint()
        	subtree:add(f_dest_mem_address, dest_mem_address)
        	offset = offset + 4
	end

        -- dissect File Path Length (1 byte)
        local file_path_len = buffer(offset + w, 1):le_uint()
        subtree:add(f_file_path_len, file_path_len)
	--file_path_len=200
	offset = offset + 1

        -- dissect File Path/Name (variable length)
	local substring_start = 0
	local count = 0
        local file_path = buffer(offset, file_path_len):string()
	for i = file_path_len-1, 1, -1 do
    		local char=string.sub(file_path, i, i) 
		 if char:match("\\.") then
        		substring_start = i
			if count == 1 then 
       			 break  -- Exit the loop once we find a special character
			end
		count = count +1
    		end
        end
	
	local new_string = string.sub(file_path, substring_start + 1)
        subtree:add(f_file_path, new_string)
        offset = offset + file_path_len
   -- end
end