From: Florin Coras <fcoras@cisco.com>
Date: Fri, 11 Apr 2025 03:55:26 +0000 (-0400)
Subject: tcp: do not scale syn-ack window
X-Git-Tag: v25.10-rc0~104
X-Git-Url: https://gerrit.fd.io/r/gitweb?a=commitdiff_plain;h=409e3e3d5d64f0e87c818e0b938774f7805994c2;p=vpp.git

tcp: do not scale syn-ack window

Type: fix

Change-Id: I1d677a8d80065644a1ddfb3884d99feee04c4756
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 15b2c92dcf1..2d43cf0f01f 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -1883,8 +1883,8 @@ tcp46_syn_sent_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
       else
 	new_tc->rcv_wscale = 0;
 
-      new_tc->snd_wnd = clib_net_to_host_u16 (tcp->window)
-			<< new_tc->snd_wscale;
+      /* RFC7323 sec 2.2: Window field in a syn segment must not be scaled */
+      new_tc->snd_wnd = clib_net_to_host_u16 (tcp->window);
       new_tc->snd_wl1 = seq;
       new_tc->snd_wl2 = ack;