From: Stephane Ouellette <ouellettes@videotron.ca>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] Is negative offset possible in u32 ?
Date: Tue, 14 Jan 2003 13:22:05 +0000 [thread overview]
Message-ID: <marc-lartc-104255062702115@msgid-missing> (raw)
In-Reply-To: <marc-lartc-104254797731703@msgid-missing>
Eric Leblond wrote:
>Has somebody realyy manage to use the examples given when using negative
>offset in u32 ?
>
>I look at the kernel code, I'm almost a real beginner here so I could
>wrote stupid things :
>
>I saw that in the file cls_u32.c we work with skb and use only
>skb->nh.raw. That's the network header, so we don't have any information
>about Ethernet header (it's in skb->mac.raw that we have the ethernet
>header and that the protocol is given).
>Furthermore (maybe i'm wrong cause of inverted stockage in memory) in
>the skbuf struct the ethernet header union follow the network header
>union so we should read something else.
>Thus we can at least say that negative offset in u32 are really "tricky"
>and really non clean and as seems to show experiment that they don't
>work (?)
>
>
>
Eric,
the following offsets are from a mail previously posted on this list.
I hope it helps.
Stephane Ouellette.
Decimal Ofs Description
-----------------------------------
-14: DST MAC, 6 bytes
-8: SRC MAC, 6 bytes
-2: Eth PROTO, 2 bytes, eg. ETH_P_IP
0: Protocol header (IP Header)
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next prev parent reply other threads:[~2003-01-14 13:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-14 12:40 [LARTC] Is negative offset possible in u32 ? Eric Leblond
2003-01-14 13:22 ` Stephane Ouellette [this message]
2003-01-14 13:28 ` Eric Leblond
2003-01-14 23:34 ` Julian Anastasov
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