Wireshark-dev: Re: [Wireshark-dev] [resend]MMS dissector bug?
From: "Anders Broman" <[email protected]>
Date: Tue, 21 Nov 2006 23:24:10 +0100
Hi,
I have reverted the changes to have named bits in the generic bitstring
defined in mms asn1 for Data.

I don’t think its possible to do a generic solution in packet-ber.c because
of the clause:

8.6.2.4	Where ITU-T Rec. X.680 | ISO/IEC 8824-1, 21.7, applies a BER
encoder/decoder can add or remove trailing 0 bits from the value.
NOTE – If a bitstring value has no 1 bits, then an encoder (as a sender's
option) may encode the value with a length of 1 and with an initial octet
set to 0 or may encode it as a bitstring with one or more 0 bits following
the initial octet.

It's not so easy to do something generic in the mms dissector as the bit
string can have an arbitrary length.
BR
Anders


________________________________________
Från: [email protected]
[mailto:[email protected]] För ronnie sahlberg
Skickat: den 21 november 2006 07:43
Till: Developer support list for Wireshark
Ämne: Re: [Wireshark-dev] [resend]MMS dissector bug?

what needs to be done is likely to check the length of the encoded bitstring
in the ber encoding and abort once all the encoded bits have been consumed
instead of continuing until the end of the ASN definition.


On 11/21/06, Anders Broman <[email protected]> wrote:
Hi,
That section was added on request. I have forgotten the reason.
But I think it was discussed on the mailing list.

The original ASN1 can be found at:
http://www.sisconet.com/downloads/mms_abstract_syntax.txt

BR
Anders
P.S
The check in message was:

Revision 18974 - (view) (download) (as text) - [select for diffs]
Modified Mon Aug 21 13:32:07 2006 UTC (3 months ago) by sahlberg 
File length: 67109 byte(s)
Diff to previous 18214
from Angel de Juan

make mms bitstrings easier to read


--
Hi, this is my new mms with some changes in order to display some data in
binary instead of hex. 

Excuse me because is not a diff from the repository, but I don't know how to
create a diff.

I also have the compiled packet-mms.c and packet-mms.h if you want it only
mail me.


-----Ursprungligt meddelande----- 
Från: [email protected]
[mailto:[email protected]] För Stephen Fisher 
Skickat: den 21 november 2006 00:40
Till: [email protected]; Developer support list for Wireshark
Ämne: Re: [Wireshark-dev] [resend]MMS dissector bug?

On Mon, Nov 20, 2006 at 11:59:32AM -0700, Steve Schaeffer wrote:

> It seems to me that an 8-bit "bit-string" should only show 8 entries
> in the packet details, not 512 as in packet #497 in the attachment to 
> bug #1229:
>                         success: bit-string (4)
>                             Padding: 3
>                             bit-string: 80 (offset0)
>                                 1... .... = offset0: True 

>                                 .... ...0 = offset511: False

I'm not familiar with the protocol, but it looks like all 512 are hard
coded into the dissector.  Does the bit-string need to be only 8 bits 
long?  Do you have access to the standards documents by chance?


Steve

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