Re: Reading a zero-terminated string in Lua dissector

[Jeff Morriss <jeff.morriss.ws () gmail com>]

Carsten Fuchs wrote:
> Hi Jeff,
>
> thanks for your reply.
>
> Am 2012-06-01 23:47, schrieb Jeff Morriss:
> > To use 'string' fields you'll need to determine the string length first.
> >
> > 'stringz' fields are strings that you're sure are NULL-terminated and 
> > so you should be
> > able to use a length of -1 (which means "continue to the NULL 
> > terminator") but I'm not
> > sure how that can be done in the Lua API (maybe you can just past -1 
> > to the length in
> > buffer()?).
>
> Well, as I need the string length in order to progress my read offset 
> into the buffer, I now just loop until I find the terminating NULL 
> character, counting loop iterations.
>
> It's not particularly elegant (at least it feels so, remember that I'm 
> still new to writing Wireshark dissectors), but I've now used it for a 
> while and it works very well.

Hmm, yeah, that does seem a bit silly; there should be a better way. 
Maybe the Lua API needs an equivalent of tvb_strsize().  I don't know a 
lot about Lua so I wouldn't hazard such an enhancement so you might want 
to open a bug report (https://bugs.wireshark.org) so someone who does 
know it might code it up.
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