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Commit bc26ccd8 authored by Andrey Vagin's avatar Andrey Vagin Committed by David S. Miller
Browse files

tcp: restore rcv_wscale in a repair mode (v2) 



rcv_wscale is a symetric parameter with snd_wscale.

Both this parameters are set on a connection handshake.

Without this value a remote window size can not be interpreted correctly,
because a value from a packet should be shifted on rcv_wscale.

And one more thing is that wscale_ok should be set too.

This patch doesn't break a backward compatibility.
If someone uses it in a old scheme, a rcv window
will be restored with the same bug (rcv_wscale = 0).

v2: Save backward compatibility on big-endian system. Before
    the first two bytes were snd_wscale and the second two bytes were
    rcv_wscale. Now snd_wscale is opt_val & 0xFFFF and rcv_wscale >> 16.
    This approach is independent on byte ordering.

Cc: David S. Miller <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
CC: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarAndrew Vagin <avagin@openvz.org>
Acked-by: default avatarPavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8ea853fd

net/ipv4/tcp.c

+10 −3
Original line number Diff line number Diff line
@@ -2331,10 +2331,17 @@ static int tcp_repair_options_est(struct tcp_sock *tp, 
			tp->rx_opt.mss_clamp = opt.opt_val;

			break;

		case TCPOPT_WINDOW:

			if (opt.opt_val > 14)

			{

				u16 snd_wscale = opt.opt_val & 0xFFFF;

				u16 rcv_wscale = opt.opt_val >> 16;



				if (snd_wscale > 14 || rcv_wscale > 14)

					return -EFBIG;



			tp->rx_opt.snd_wscale = opt.opt_val;

				tp->rx_opt.snd_wscale = snd_wscale;

				tp->rx_opt.rcv_wscale = rcv_wscale;

				tp->rx_opt.wscale_ok = 1;

			}

			break;

		case TCPOPT_SACK_PERM:

			if (opt.opt_val != 0)