Hiya Mike,
My guess would be that you're using volatility-2.0, but the packetscan
prototype that I put on issue 233 is only suitable for use with the
latest trunk (which will hopefully become volatility-2.1 in the next
month or two).
If you're intending to write your own scanner then it should be a
relatively suitable template to work from. I would recommend keeping
your structures as vtypes if they're simple enough. If they require
particularly complex parsing (conditionals, etc), then you may want to
just extract the appropriate amount of data and have a separate parser
that handles them.
Hope that helps? Do let me know on issue 233 if you have any other
problems with the packetscan prototype. It doesn't do everything yet,
but hopefully won't require too much work to be useful...
Mike 5:)