Hi,
That ensures things are picked up and
tracked.
Thanx,
Jaap
Hi Guy, > Message: 2
> Date: Fri, 04 Apr 2008 02:17:34 -0700
>
From: Guy Harris <guy@xxxxxxxxxxxx>
> Subject: Re: [Wireshark-dev]
Share CRC32C code between MPA and iSCSI
> To: Developer support list for
Wireshark <wireshark-dev@xxxxxxxxxxxxx>
> Cc: markb@xxxxxxxxxx,
geyves@xxxxxxxxxxxxxxx
> Message-ID:
<47F5F22E.2040102@xxxxxxxxxxxx>
> Content-Type: text/plain;
charset=ISO-8859-1; format=flowed
>
> Philip Frey1 wrote:
>
> > we have developed a dissector for the MPA (Marker PDU Aligned
Framing)
> > protocol which is part of the iWARP stack.
> >
Since we also need to do some CRC32C calculations (same as iSCSI),
>
> ...and, it appears, SCTP.
Good
catch.
> The SCTP dissector has the same
CRC table; its CRC routine starts with
> 0xFFFFFFFF - which, when
byte-swapped, is unchanged - and then adds in
> to the CRC a bunch of
bytes and 0's, flips the bits in the result, and
> then swaps the bytes.
Your CRC32 routine doesn't flip the bits, so the
> right way to
combine them might be to:
>
> export the CRC32 table
from crc32c.c, declaring it in crc32.h;
>
> moving the
CRC32C macro from packet-sctp.c to crc32.h;
>
> moving
the CRC32C_SWAP macro from crc32c.c to crc32.h (or see whether
> GLib
1.2.x and 2.x define something equivalent, and use that);
>
>
have calculate_crc32() use the CRC32C macro:
>
>
guint32 calculate_crc32(const void *buf, int len, guint32 crc)
> {
>
const guint8 *p = (const guint8 *)buf;
> crc =
CRC32C_SWAP(crc);
> while (len-- > 0) {
>
CRC32C(crc, *p++);
> }
>
return CRC32C_SWAP(crc);
> }
>
> have
sctp_crc32c() use CRC32C_PRELOAD instead of ~0L.
>
> There might be
some other merging that could be done.
I
have implemented exactly as you suggested (assuming I understood your
suggestion correctly). :-D
Please find attached the modified files:
(I merged everything into the crc32-files and got rid of
the crc32c files) If that is what
you had in mind, then I will contribute it by sending my diff
to the bug-list of wireshark (as suggested in the
README.developer). Cheers,
Phil
