Wireshark · Wireshark-dev: Re: [Wireshark-dev] Wireshark-dev Digest, Vol 23, Issue 11

[Philip Frey1 <PHF@xxxxxxxxxxxxxx>]

Hi Jaap,

thanks for the pointer. I have created
a new bug report and added the diff there.
I hope it worked. Can you see my request?

Many thanks,
 Philip

"Jaap Keuter" <jaap.keuter@xxxxxxxxx>
Sent by: wireshark-dev-bounces@xxxxxxxxxxxxx

04.04.2008 20:28

Please respond to
Developer support list for Wireshark <wireshark-dev@xxxxxxxxxxxxx>

To	"'Developer support list for Wireshark'" <wireshark-dev@xxxxxxxxxxxxx>
cc
Subject	Re: [Wireshark-dev] Wireshark-dev Digest, Vol 23, Issue 11

Hi,
 
Please adhere to the patch submission
policy: http://wiki.wireshark.org/SendingFilesToWireshark
That ensures things are picked
up and tracked.
 
Thanx,
Jaap

---

From: wireshark-dev-bounces@xxxxxxxxxxxxx
[mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] On Behalf Of Philip
Frey1
Sent: 2008-Apr-04 18:23
To: wireshark-dev@xxxxxxxxxxxxx
Cc: geyves@xxxxxxxxxxxxxxx
Subject: Re: [Wireshark-dev] Wireshark-dev Digest, Vol 23, Issue 11


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_______________________________________________
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