Wireshark · Ethereal-dev: Re: [Ethereal-dev] Re: New dissectors: H.223 and friends

[Richard van der Hoff <richardv@xxxxxxxxxxxxx>]

Guy Harris wrote:
> Richard van der Hoff wrote:
>
> > However, I've spotted a bug in the new desegmentation in iax2, which 
> > means that higher-level PDUs aren't dissected when they ought to be, 
> > but tend to be grouped together in later packets - I've attached a 
> > patch against svn r16110 to fix this; it also makes the code a bit 
> > clearer...
>
>
> Are those higher-level PDUs always in order, so that there's no sequence 
> number in them?  If so, then you should be using "fragment_add_seq_next()".

You may well be right - I'm not entirely sure why Jeff chose 
fragment_add(), but I imagine it was because he based the code on the 
TCP dissector.

However, I'm not clear on what "id" is used for in 
fragment_add_seq_next() - it doesn't seem to be mentioned in the 
comments. Could you explain?

> That would probably be a good thing, as the code currently will, on the 
> first pass, set "complete" to TRUE even if the "fragment_add()" call 
> returns NULL, causing a null pointer dereference crash, at least with 
> some captures, when it tries to use "fd_head" to point to values to use 
> as arguments to "tvb_new_real_data()".
>
> See bugs 515 through 519.

Indeed, I'd spotted those over the weekend and flagged them for 
attention this morning :).

Richard


--
Richard van der Hoff <richardv@xxxxxxxxxxxxx>
Systems Analyst
Tel: +44 (0) 845 666 7778
http://www.mxtelecom.com