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From: Hyong Youb Kim <hyonkim@cisco.com>
To: Olivier Matz <olivier.matz@6wind.com>
Cc: Ferruh Yigit <ferruh.yigit@intel.com>,
	Shyam Shrivastav <shrivastav.shyam@gmail.com>,
	lidejun1@huawei.com, users <users@dpdk.org>,
	dev@dpdk.org, lichunhe@huawei.com, zhangxufeng4@huawei.com
Subject: Re: [dpdk-users] [dpdk-dev] IPV4/IPV6 TCP/UDP Pseudo Header Checksum APIs
Date: Thu, 29 Nov 2018 00:07:19 +0900	[thread overview]
Message-ID: <20181128150718.GA25832@HYONKIM-7R0DR.cisco.com> (raw)
In-Reply-To: <20181023090158.z5w3gtvdzax247w6@platinum>

On Tue, Oct 23, 2018 at 11:01:58AM +0200, Olivier Matz wrote:
> Hi,
> 
> You are right, the current code does not take IP or IPv6 options
> in account. I think this should be considered as a bug.
> 
> The fix for IPv4 is not complicated, I did a quick draft here:
> http://git.droids-corp.org/?p=dpdk.git;a=commitdiff;h=96a6978ef6814e1450e1bd65fbce91c3d85b3121
> 
> For IPv6, it is more complex than expected:
> https://tools.ietf.org/html/rfc2460.html#section-8.1
> 
> - we need to skip extension headers
> - we need to parse routing headers and use the proper destination
>   address in the pseudo header checksum
> 
> This makes me think that the API is not adequate. Asking the user
> to provide the headers in a contiguous memory without specifying
> the length is quite dangerous, especially if the header comes from
> outside, as it can trigger out of bound accesses.
> 
> I wonder if we shouldn't switch to a mbuf based API instead, and
> deprecate the old one.
> 
> Thoughts?
> Olivier
> 

I have been looking into a similar issue because
rte_net_intel_cksum_prepare(), which is used by most tx_pkt_prepare
handlers, does not work when ipv6 extensions are present. That
function is using rte_ipv6_phdr_cksum(). And this makes
rte_eth_tx_prepare() kinda useless for any workloads that encounter
ipv6 extensions.

There are 2 routing header types now (2 and 3).

https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#ipv6-parameters-3

In addition to these routing headers, there is also ipv6
mobility. Pseudo header's source address is supposed to be the address
in the Home Address option.

https://tools.ietf.org/html/rfc6275#page-36

Who knows there may be future extensions that affect pseudo
header.. We can probably make rte_ipv6_phdr_cksum() to understand all
existing headers that affect pseudo header, but it will still not be future
proof. Should at least document the limitations for rte_ipv6_phdr_cksum()..

-Hyong

      parent reply	other threads:[~2018-11-28 15:07 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-20  3:32 [dpdk-users] " lidejun
2018-10-20  5:12 ` [dpdk-users] [dpdk-dev] " Shyam Shrivastav
2018-10-20  5:22   ` Shyam Shrivastav
2018-10-20  6:14     ` [dpdk-users] 答复: " lidejun
2018-10-20  6:30       ` [dpdk-users] " Shyam Shrivastav
2018-10-22  8:03         ` Ferruh Yigit
2018-10-23  9:01           ` Olivier Matz
2018-10-23 10:53             ` Shyam Shrivastav
2018-11-28 15:07             ` Hyong Youb Kim [this message]

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