[PATCHv4 6/7] Allow to turn off TCP window scale opt per route
From: Gilad Ben-Yossef <hidden>
Date: 2009-10-28 14:15:30
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
Add and use no window scale bit in the features field. Note that this is not the same as setting a window scale of 0 as would happen with window limit on route. Signed-off-by: Gilad Ben-Yossef <redacted> Sigend-off-by: Ori Finkelman [off-list ref] Sigend-off-by: Yony Amit [off-list ref] --- include/linux/rtnetlink.h | 1 + net/ipv4/tcp_input.c | 3 ++- net/ipv4/tcp_output.c | 6 ++++-- 3 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 2ab8c75..6784b34 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h@@ -380,6 +380,7 @@ enum #define RTAX_FEATURE_NO_SACK 0x00000002 #define RTAX_FEATURE_NO_TSTAMP 0x00000004 #define RTAX_FEATURE_ALLFRAG 0x00000008 +#define RTAX_FEATURE_NO_WSCALE 0x00000010 struct rta_session {
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d2f9742..4f5e914 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c@@ -3739,7 +3739,8 @@ void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx, break; case TCPOPT_WINDOW: if (opsize == TCPOLEN_WINDOW && th->syn && - !estab && sysctl_tcp_window_scaling) { + !estab && sysctl_tcp_window_scaling && + !dst_feature(dst, RTAX_FEATURE_NO_WSCALE)) { __u8 snd_wscale = *(__u8 *)ptr; opt_rx->wscale_ok = 1; if (snd_wscale > 14) {
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8f30c18..ff60a21 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c@@ -496,7 +496,8 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb, opts->tsecr = tp->rx_opt.ts_recent; size += TCPOLEN_TSTAMP_ALIGNED; } - if (likely(sysctl_tcp_window_scaling)) { + if (likely(sysctl_tcp_window_scaling && + !dst_feature(dst, RTAX_FEATURE_NO_WSCALE))) { opts->ws = tp->rx_opt.rcv_wscale; opts->options |= OPTION_WSCALE; size += TCPOLEN_WSCALE_ALIGNED;
@@ -2347,7 +2348,8 @@ static void tcp_connect_init(struct sock *sk) tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), &tp->rcv_wnd, &tp->window_clamp, - sysctl_tcp_window_scaling, + (sysctl_tcp_window_scaling && + !dst_feature(dst, RTAX_FEATURE_NO_WSCALE)), &rcv_wscale); tp->rx_opt.rcv_wscale = rcv_wscale;
--
1.5.6.3