netdev - Re: [PATCH net] tcp: properly scale window in tcp_v[46]_reqsk_send

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Date:   Mon, 22 Aug 2016 14:59:10 -0400
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Yuchung Cheng <ycheng@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net] tcp: properly scale window in tcp_v[46]_reqsk_send_ack()

On Mon, Aug 22, 2016 at 2:31 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> When sending an ack in SYN_RECV state, we must scale the offered
> window if wscale option was negotiated and accepted.
>
> Tested:
>  Following packetdrill test demonstrates the issue :
>
> 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
> +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
>
> +0 bind(3, ..., ...) = 0
> +0 listen(3, 1) = 0
>
> // Establish a connection.
> +0 < S 0:0(0) win 20000 <mss 1000,sackOK,wscale 7, nop, TS val 100 ecr 0>
> +0 > S. 0:0(0) ack 1 win 28960 <mss 1460,sackOK, TS val 100 ecr 100, nop, wscale 7>
>
> +0 < . 1:11(10) ack 1 win 156 <nop,nop,TS val 99 ecr 100>
> // check that window is properly scaled !
> +0 > . 1:1(0) ack 1 win 226 <nop,nop,TS val 200 ecr 100>
>
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Yuchung Cheng <ycheng@...gle.com>
> Cc: Neal Cardwell <ncardwell@...gle.com>
> ---

Acked-by: Neal Cardwell <ncardwell@...gle.com>

Nice.

neal