Wireshark-dev: Re: [Wireshark-dev] Invitation to discuss possible dissector for SCSI-OSD
Hi,
There is an initial dissector for SCSI OSD in current SVN that
dissects some CDBs.
While implementing this i uncovered some flaws with the iscsi
dissector that did not handle AHS properly, but it should work now.
There is still a bug in the iscsi dissector where it fails to
automatically detect that there is a HEADER DIGEST provided in the
PDU, which leads to the dissector of DATA IN/OUT starting off at the
wrong offset (4 bytes to early).
I can not look into this HEADER DIGEST autodetection regression right
now so for the time being I would suggest just focusing on the CDBs
and ignoring the DATA dissection.
I will look into why the autodetection doesnt work later.
A temporary workaround for this issue is to force the iscsi dissector
to always use crc32 header digests which can be done by changing the
line (in packet-iscsi.c)
iscsi_session->header_digest=ISCSI_HEADER_DIGEST_AUTO;
into
iscsi_session->header_digest=ISCSI_HEADER_DIGEST_CRC32;
On 9/29/06, Joe Breher <linux@xxxxxxxxxxx> wrote:
Ronnie -
Some example traces should be in your personal inbox. I need to do some
checking to see whether I am at liberty to release them to the public at
large. I'll find some way to make that happen.
For those who may be following along:
I guess I've committed to the task of adding some SCSI-OSD-specific info
to the wiki. I've never edited a wiki before, so please be patient.
It sounds like Ronnie may be willing to at least advise me on design
decisions within the SCSI dissector - or perhaps even actively
contribute to the coding. Such would be very appreciated, as I do not
yet know where to start on this task.
ronnie sahlberg wrote:
> Hi,
>
> Since there are many opcodes in OSD that are from SPC I think the best
> solution would probably be to
> implement everything except opcode 0x7f in the existing dissector and
> implement the OSD specific bits (opcode 0x7f)
> in a new packet-scsi-osd.c
>
>
> Adding an initial dissector for OSD that at least includes all the
> opcodes that are shared from SPC would be trivial and I can do that
> tonight.
>
>
> Do you have example captures with OSD traffic you can share?
>
>
>
>
> On 9/28/06, *Joe Breher* <linux@xxxxxxxxxxx
> <mailto:linux@xxxxxxxxxxx>> wrote:
>
> With much embarrassment, I note that I neglected to change the Subject
> of my last post (quoted herein). This reply should be near my last
> post
> in the digest, thereby hopefully eliminating some confusion.
>
> Joe Breher wrote:
> > ronnie sahlberg wrote:
> >
> >> Please do so. It would be very nice to add one more transport
> for our
> >> SCSI dissector.
> >>
> >>
> > Ronnie (et al) -
> >
> > It may be time for me to go public with the reason for my desire to
> > become involved with wireshark development. In essence, I am in
> need of
> > a dissector for SCSI-OSD. This is an INCITS T10 Technical Committee
> > ratified Standard for a command set for Object-based Storage
> Devices.
> > This is a full command layer as SBC, SMC, etc, that are already
> > supported in the wireshark SCSI dissector.
> >
> > I still am not familiar enough with the wireshark SCSI dissector
> code to
> > have opinions on the matter. Accordingly, now is probably an
> opportune
> > time for discussion ;-).
> >
> > It is unclear to me at this point whether it makes more sense to
> extend
> > the current SCSI dissector, or to develop a new one for OSD. I'd
> like to
> > extend the current one. However, there are several unique
> challenges in
> > OSD that do not exist in any of the command sets that the current
> > dissector in packet-scsi.c currently handles. Among these are :
> > - Variable Length CDBs
> > - 'opcode' is x7F for all commands - the 'effective opcode' is
> actually
> > a two-byte Service Action in bytes CDB[9..8]
> > - bidirectional data transfers - Data In *and* Data Out 'phases'
> ('IUs',
> > 'PDUs', whatever) during the execution of a *single* command.
> > the list goes on.
> >
> > I would love to hear from anyone who either has an interest in these
> > aspects of SCSI, or has insight into the design decisions behind the
> > current SCSI dissector.
> > _______________________________________________
> > Wireshark-dev mailing list
> > Wireshark-dev@xxxxxxxxxxxxx <mailto:Wireshark-dev@xxxxxxxxxxxxx>
> > http://www.wireshark.org/mailman/listinfo/wireshark-dev
> <http://www.wireshark.org/mailman/listinfo/wireshark-dev>
> >
>
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