Hi,
Sounds good to me, I've been considering if we need
Different proto_tree_add_bits_ret_val()s
for 8 16 32 and 64 bits what do you think?
Regards
Anders
-----Ursprungligt meddelande-----
Från: wireshark-dev-bounces@xxxxxxxxxxxxx
[mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] För Richard van der Hoff
Skickat: den 15 april 2008 19:43
Till: Developer support list for Wireshark
Ämne: Re: [Wireshark-dev] New proto_add_bits function (Was:rev
21556:/trunk/epan//tr...)
Hi all, and Anders in particular:
Anders Broman (AL/EAB) wrote:
> Hi,
> I have used it in the h263 dissector with a h263 prefix unfortunatly there
is only short sequences
> Beeing dissected most being the same in all h263 frames :(
> Perhaps it can be used in the PER dissector but I didn't want to use it
before we had agreed on a format to
> avoid to many changes.
> Regrads
> Anders
I've just been investigating why packet colouring and display-filters
weren't working on h263 picture headers. It turns out that the problem
was that proto_tree_add_bits_ret_val extracts the value, returning 0 or
1 (for a 1-bit field); proto_tree_set_uint then applies the bitmask
specified in the hf_field definition - giving 0 for most fields.
It seems to me that the bitmask should be 0 for all fields intended for
use with proto_tree_add_bits_*.
I've fixed this for h263 in r25050, but I'm concerned that there will
other cases, both now (h264, maybe?) and in the future - and that such
bugs will once again lie dormant until somebody tries to filter on the
offending fields.
I'd therefore like to propose adding this to proto_tree_add_bits_ret_val:
+ if(hf_field -> bitmask != 0) {
+ REPORT_DISSECTOR_BUG(ep_strdup_printf("Incompatible use
of proto_tree_add_bits_ret_val with field '%s' (%s) with bitmask != 0",
+
hf_field->abbrev, hf_field->name));
+ }
+
Comments?
Cheers
Richard
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