From: Daniel Borkmann <daniel@iogearbox.net>
To: "Panneman, J.J. (Jeffrey)" <jeffrey.panneman@tno.nl>
Cc: "xdp-newbies@vger.kernel.org" <xdp-newbies@vger.kernel.org>
Subject: Re: UDP checksum calculation
Date: Wed, 28 Jun 2017 11:18:11 +0200 [thread overview]
Message-ID: <59537453.6080407@iogearbox.net> (raw)
In-Reply-To: <7784F3C775469047B0E8C3B494DB28BEB1B143@EXC-MBX03.tsn.tno.nl>
On 06/28/2017 10:46 AM, Panneman, J.J. (Jeffrey) wrote:
> Hi All,
>
> I posted this question in the Cillium Slack too, but I figured posting it here might help other people too.
> I checked out the Cillium source(from what I see makes use of the provided tc-helpers: https://github.com/cilium/cilium/blob/master/bpf/lib/csum.h), but is there an appropriate way to do checksum (re)calculation for UDP with XDP ? Since it does not really like long loops that much and the payload possibly being quite long. I don't really see a way to loop over the payload to recalculate the checksum, would anyone perhaps have a code snippet for this ?
Depends on the use-case, are you rewriting also UDP payload
in XDP? If not, why is [1] not sufficient resp. a variant of
that which calcs the diff? csum_diff() could be an option, but
why not doing it in BPF itself?
[1] http://lingrok.org/xref/linux-net-next/tools/testing/selftests/bpf/test_xdp.c#141
prev parent reply other threads:[~2017-06-28 9:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <7784F3C775469047B0E8C3B494DB28BEB1B126@EXC-MBX03.tsn.tno.nl>
2017-06-28 8:46 ` UDP checksum calculation Panneman, J.J. (Jeffrey)
2017-06-28 9:18 ` Daniel Borkmann [this message]
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