From: Florin Coras <fcoras@cisco.com>
Date: Thu, 13 Dec 2018 03:25:43 +0000 (-0800)
Subject: tcp: fix handling of no wscale in syns
X-Git-Tag: v19.04-rc0~178
X-Git-Url: https://gerrit.fd.io/r/gitweb?a=commitdiff_plain;h=refs%2Fchanges%2F53%2F16453%2F2;p=vpp.git

tcp: fix handling of no wscale in syns

Change-Id: I7219a8d315b312812acafd9d2709fba8b4a2a679
Signed-off-by: Florin Coras <fcoras@cisco.com>
---

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 395943739e8..fc1aff40747 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -2480,6 +2480,8 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
       if (tcp_opts_wscale (&new_tc0->rcv_opts))
 	new_tc0->snd_wscale = new_tc0->rcv_opts.wscale;
+      else
+	new_tc0->rcv_wscale = 0;
 
       new_tc0->snd_wnd = clib_net_to_host_u16 (tcp0->window)
 	<< new_tc0->snd_wscale;
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 7cee34995e3..113fb148c37 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -126,7 +126,10 @@ tcp_initial_window_to_advertise (tcp_connection_t * tc)
    * scale to be computed in the same way */
   max_fifo = tm->max_rx_fifo ? tm->max_rx_fifo : TCP_MAX_RX_FIFO_SIZE;
 
-  tc->rcv_wscale = tcp_window_compute_scale (max_fifo);
+  /* Compute rcv wscale only if peer advertised support for it */
+  if (tc->state != TCP_STATE_SYN_RCVD || tcp_opts_wscale (&tc->rcv_opts))
+    tc->rcv_wscale = tcp_window_compute_scale (max_fifo);
+
   tc->rcv_wnd = tcp_initial_wnd_unscaled (tc);
 
   return clib_min (tc->rcv_wnd, TCP_WND_MAX);