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From: Stephen Hemminger <stephen@networkplumber.org>
To: guohongzhi <guohongzhi1@huawei.com>
Cc: <dev@dpdk.org>, <stable@dpdk.org>, <olivier.matz@6wind.com>,
	<mb@smartsharesystems.com>, <konstantin.ananyev@intel.com>,
	<jiayu.hu@intel.com>, <ferruh.yigit@intel.com>,
	<nicolas.chautru@intel.com>, <cristian.dumitrescu@intel.com>,
	<zhoujingbin@huawei.com>, <chenchanghu@huawei.com>,
	<jerry.lilijun@huawei.com>, <haifeng.lin@huawei.com>
Subject: Re: [dpdk-dev] [PATCH] bugfix: udptcp_checksum should tread tcp and udp differently
Date: Wed, 27 May 2020 08:02:42 -0700
Message-ID: <20200527080242.16dceeae@hermes.lan> (raw)
In-Reply-To: <20200527144127.5792-1-guohongzhi1@huawei.com>

On Wed, 27 May 2020 22:41:27 +0800
guohongzhi <guohongzhi1@huawei.com> wrote:

> +	/* For Udp, if the computed checksum is zero,
> +	 * it is transmitted as all ones.RFC768
> +	 */
> +	if (cksum == 0 && ipv4_hdr->next_proto_id == IPPROTO_UDP)
>  		cksum = 0xffff;
>  


The comment should be reformatted to be clearer.

Maybe:
	/*
	 * Per RFC768:
	 * If the computed  checksum  is zero,it is transmitted  as all ones
	 * (the equivalent  in one's complement  arithmetic).
	 */

There is no special case required here, it is true for TCP as well.
In TCP it appears 0 is allowed but not generally used. Most implementations
use common checksum for both TCP and UDP

  reply	other threads:[~2020-05-27 15:02 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27 14:41 guohongzhi
2020-05-27 15:02 ` Stephen Hemminger [this message]
2020-05-27 15:36   ` Morten Brørup
2020-07-06  7:58     ` Olivier Matz
  -- strict thread matches above, loose matches on Subject: below --
2020-05-27 14:40 guohongzhi

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