Wireshark-dev: Re: [Wireshark-dev] Byte Ordering in Dissector
From: "Barry Constantine" <[email protected]>
Date: Wed, 30 Apr 2008 10:46:09 -0700
Thanks a bunch folks!!

-Barry

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Guy Harris
Sent: Wednesday, April 30, 2008 1:41 PM
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] Byte Ordering in Dissector

Barry Constantine wrote:

> I am running into a problem because the uint32 of my protocol is not
in 
> network byte order, but is in reverse byte order.
> 
> How can I override the default assumption of network byte order when I

> insert the uint32 into the dissector tree?

You can't...

...because there isn't any default assumption to override!

If you're using proto_tree_add_item(), ptvcursor_add(), or 
ptvcursor_add_no_advance(), just specify TRUE rather than FALSE as the 
last argument, to indicate that the value is little-endian rather than 
big-endian.

If you're using the ptvcursor routines, specify TRUE rather than FALSE 
as the "little_endian" argument.

If you're fetching the value yourself, and the uint32 is *NOT* an IPv4 
addressuse tvb_get_letohl() rather than tvb_get_ntohl() to convert it to

host byte order.

If you're fetching the value yourself, and the uint32 *IS* an IPv4 
address (i.e., an IPv4 address stored, for some mysterious reason, in 
little-endian byte order rather than big-endian network byte order), use

tvb_get_ipv4() and then byte-swap the value with GUINT32_SWAP_LE_BE().
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