From bc26ccd8fc756749de95606d28314efd0ce5aec3 Mon Sep 17 00:00:00 2001 From: Andrey Vagin Date: Wed, 19 Sep 2012 09:40:00 +0000 Subject: 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 Cc: Alexey Kuznetsov Cc: James Morris Cc: Hideaki YOSHIFUJI Cc: Patrick McHardy CC: Pavel Emelyanov Signed-off-by: Andrew Vagin Acked-by: Pavel Emelyanov Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index bf9a8ab29459..5f6419341821 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -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) - return -EFBIG; + { + 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) -- cgit v1.2.1