Re: [Wireshark-commits] master fe195c0: Don't throw for offset at end of TVB with len -1.

[Guy Harris <guy () alum mit edu>]

On Apr 25, 2014, at 2:48 PM, Evan Huus <eapache () gmail com> wrote:

> I think conceptually what we need is a way to say "this item isn't
> associated with any bytes at all, so don't do any bounds checks etc".
> Negative offsets are already taken in the general case; do we need to
> special-define a length of -2 for this?

I'd actually like to see lengths become *unsigned*; currently, we need to do some hackery to make sure that

        length = tvb_get_ntohl(tvb, offset);

                ...

        offset += 4;

                ...

        proto_tree_add_whatever(..., offset, length, ...);

to handle the case where the length has the uppermost bit set.

Perhaps there needs to be a call or calls to add items that don't correspond to packet data; those calls might take 
neither an offset argument nor a length argument (nor even a tvbuff argument?), and would not do any bounds checking.  
Obviously, they'd have to take an argument corresponding to the value of the item.

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