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From: Stefano Brivio <sbrivio@redhat.com>
To: passt-dev@passt.top
Cc: Paul Holzinger <pholzing@redhat.com>,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH] checksum: Fix calculation for ICMP checksum on IPv4
Date: Tue, 25 Oct 2022 19:25:41 +0200	[thread overview]
Message-ID: <20221025192541.18e837af@elisabeth> (raw)
In-Reply-To: <20221025160713.1024373-1-sbrivio@redhat.com>

On Tue, 25 Oct 2022 18:07:13 +0200
Stefano Brivio <sbrivio@redhat.com> wrote:

> We need to zero out the checksum field before calculating the
> checksum, of course. I have no idea how this passed the "icmp" test
> set, looking into it.

That's because the version of ping(8) I use on my test machine, from
'iputils', ignores a failed checksum in the reply:

  https://github.com/iputils/iputils/blob/59908434d7505ef574c2e0811ad1d5edb671845a/ping/ping.c#L1544

...the parameter 'csfailed' in gather_statistics() is just passed as 0
here. The checksum was actually wrong in the CI test run.

Forcing a specific version (e.g. from GNU inetutils) looks rather messy
and non-portable, so I'm afraid there isn't much we can do for this,
other than being careful.

-- 
Stefano


  reply	other threads:[~2022-10-25 17:25 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-25 16:07 [PATCH] checksum: Fix calculation for ICMP checksum on IPv4 Stefano Brivio
2022-10-25 17:25 ` Stefano Brivio [this message]
2022-10-26  0:06 ` David Gibson
     [not found]   ` <CAFsF8v+x-c=Rk6z+-hwwFWt0PvEu10u-rpkQ4F=Z2jbfAJPoww@mail.gmail.com>
2022-10-26 12:57     ` Stefano Brivio
     [not found]       ` <CAFsF8vLk_Qyva32Z5pH5Jic+NeFKrnaPLm_pw_QDARfjdiXQvQ@mail.gmail.com>
2022-10-26 13:40         ` Stefano Brivio
2022-10-26 14:28           ` Stefano Brivio

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