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We are looking to update the model for source generating common electronic exchanges protocols.

Currently a message may look like this:

-- Calculate size of: Trade Report Message
n24x_equities_memoirlastsale_sbe_v1_3_size_of.trade_report_message = function(buffer, offset)
  local index = 0

  index = index + n24x_equities_memoirlastsale_sbe_v1_3_size_of.timestamp

  index = index + n24x_equities_memoirlastsale_sbe_v1_3_size_of.security_id

  index = index + n24x_equities_memoirlastsale_sbe_v1_3_size_of.trade_id

  index = index + n24x_equities_memoirlastsale_sbe_v1_3_size_of.trade_qty

  index = index + n24x_equities_memoirlastsale_sbe_v1_3_size_of.trade_price

  return index
end

-- Display: Trade Report Message
n24x_equities_memoirlastsale_sbe_v1_3_display.trade_report_message = function(buffer, offset, size, packet, parent)
  return ""
end

-- Dissect Fields: Trade Report Message
n24x_equities_memoirlastsale_sbe_v1_3_dissect.trade_report_message_fields = function(buffer, offset, packet, parent)
  local index = offset

  -- Timestamp: 8 Byte Unsigned Fixed Width Integer
  index, timestamp = n24x_equities_memoirlastsale_sbe_v1_3_dissect.timestamp(buffer, index, packet, parent)

  -- Security Id: 2 Byte Unsigned Fixed Width Integer
  index, security_id = n24x_equities_memoirlastsale_sbe_v1_3_dissect.security_id(buffer, index, packet, parent)

  -- Trade Id: 8 Byte Unsigned Fixed Width Integer
  index, trade_id = n24x_equities_memoirlastsale_sbe_v1_3_dissect.trade_id(buffer, index, packet, parent)

  -- Trade Qty: 4 Byte Unsigned Fixed Width Integer
  index, trade_qty = n24x_equities_memoirlastsale_sbe_v1_3_dissect.trade_qty(buffer, index, packet, parent)

  -- Trade Price: 8 Byte Signed Fixed Width Integer
  index, trade_price = n24x_equities_memoirlastsale_sbe_v1_3_dissect.trade_price(buffer, index, packet, parent)

  return index
end

-- Dissect: Trade Report Message
n24x_equities_memoirlastsale_sbe_v1_3_dissect.trade_report_message = function(buffer, offset, packet, parent)
  -- Optionally add struct element to protocol tree
  if show.trade_report_message then
    local length = n24x_equities_memoirlastsale_sbe_v1_3_size_of.trade_report_message(buffer, offset)
    local range = buffer(offset, length)
    local display = n24x_equities_memoirlastsale_sbe_v1_3_display.trade_report_message(buffer, packet, parent)
    parent = parent:add(n24x_equities_memoirlastsale_sbe_v1_3.fields.trade_report_message, range, display)
  end

  return n24x_equities_memoirlastsale_sbe_v1_3_dissect.trade_report_message_fields(buffer, offset, packet, parent)
end

In the cases where the source generated inputs do not match the packet capture, the above code errors out on the line:

local range = buffer(offset, length)

This is a fundamental flaw when testing source generated dissectors because Wireshark errors out at the message level. It would be preferred to dissect as many message fields as possible first to see how close the binary data model is to the actual data.

Can I give the add a dummy buffer and set it after? Or is there another preferred solution?

Thanks in advance