Ethereal-dev: [Ethereal-dev] Re: Asn.1 and indefinite length. ->FTAM ASN.1 Spec.
Hi The ASN.1 spec of FTAM is available at:
http://www.itu.int/ITU-T/asn1/database/iso/8571-4/1988/
Best regards
Anders
>The handling of indefinite length is very incomplete in packet-ber.
>Mainly due to that indefinite length encodings are very uncommon in
>those protocols that mainly use packet-ber.c
>
>I would definitely be interested in refining packet-ber so that it
>starts doing proper handling of indefinite length fields the correct
>way but will not have time to do so in the next few weeks.
>
>Please ping me in two weeks time and i can start looking at it.
>
>I would also need an example capture with several indefinite lengths
>in it, as your example you describe plus the ASN specification for the
>protocol.
>(ill then hack up a quick test asn2eth generated version of the
>protocol for testing the indefinite length handling but not check in
>that autogenerated protocol)
>
>
>>On 5/20/05, Yuriy Sidelnikov <YSidelnikov@xxxxxxxx> wrote:
>> Anders Broman wrote:
>> Let's say we've sequence:
>>
>> af - tag 1
>> 80 - len1
>> 72 - tag2
>> 80 - len2
>> ... something related to tag2
>> ... something related to tag1
>> 0000 - first delimeter(end of tag2)
>> 0000 - second delimiter(end of tag1)
>> a1 - another tags
>> 8101
>> 01
>> a2
>> 820001
>> 01
>> end of tvb.
>>
>> Both API will return wrong length, for example, for x'af' tag from x'72'
>to
>>
>> the end of tvb buffer.But correct value will be from x'72' to the second
>> delimeter.
>>
>> Regards,
>> Yuriy.
>>
>>
>> >>Hi,
>> >>analyzing some new ftam trace files I found that the indefinite length
>in
>> >>the ASN.1 is not so rare thing as I thought.
>> >>So I would like to have correct ASN.1 API.
>> >>The question is that neither obsolete asn1.c nor new packet-ber.c can
>> >>handle with the indefinite length in asn.1 stream.
>> >>So what is the better:
>> >>1.Add support for the indefinite length say "over" asn1.c.It is not
>very
>> >>hard so we'll have working dissector pretty soon.Really I need only one
>> >>thing more - to get correct length in case of the indefinite length.
>> >>2.Try to use new api in the packet-ftam/acse/pres keeping in mind that
>> >>somebody will be so kind to add the support for the indefinite length.
>> It's
>> >>not very easy way to go.
>> >>
>> >>Regards,
>> >>Yuriy Sidelnikov
>> >
>> > As far as I know both packet-ber.c and the asn1.c handle at least some
>> > indefinite lengths, what exactly is it you are missing?
>> >
>> > Best regards
>> > Anders
>> >
>> >
