From 881dd9d62d034ce23268e31691aa59c478fada43 Mon Sep 17 00:00:00 2001
From: "chao.an" <anchao@xiaomi.com>
Date: Mon, 7 Dec 2020 14:12:59 +0800
Subject: [PATCH] net/tcp: add a member to record the current receiving window

Change-Id: Ic4c46d643a905fdd3a828e563eab4814da70dbe5
Signed-off-by: chao.an <anchao@xiaomi.com>
---
 net/sixlowpan/sixlowpan_tcpsend.c | 4 ++++
 net/tcp/tcp.h                     | 1 +
 net/tcp/tcp_send.c                | 4 ++++
 3 files changed, 9 insertions(+)

diff --git a/net/sixlowpan/sixlowpan_tcpsend.c b/net/sixlowpan/sixlowpan_tcpsend.c
index b0b0277f8b..29ca5dc5c8 100644
--- a/net/sixlowpan/sixlowpan_tcpsend.c
+++ b/net/sixlowpan/sixlowpan_tcpsend.c
@@ -263,6 +263,10 @@ static int sixlowpan_tcp_header(FAR struct tcp_conn_s *conn,
 
       ipv6tcp->tcp.wnd[0] = recvwndo >> 8;
       ipv6tcp->tcp.wnd[1] = recvwndo & 0xff;
+
+      /* Update the Receiver Window */
+
+      conn->rcv_wnd = recvwndo;
     }
 
   /* Calculate TCP checksum. */
diff --git a/net/tcp/tcp.h b/net/tcp/tcp.h
index fc67f45f21..a3649b88ec 100644
--- a/net/tcp/tcp.h
+++ b/net/tcp/tcp.h
@@ -194,6 +194,7 @@ struct tcp_conn_s
                            * connection */
   uint16_t snd_wnd;       /* Sequence and acknowledgement numbers of last
                            * window update */
+  uint16_t rcv_wnd;       /* Receiver window available */
 #ifdef CONFIG_NET_TCP_WRITE_BUFFERS
   uint32_t tx_unacked;    /* Number bytes sent but not yet ACKed */
 #else
diff --git a/net/tcp/tcp_send.c b/net/tcp/tcp_send.c
index ee82f00383..190d4e6ee9 100644
--- a/net/tcp/tcp_send.c
+++ b/net/tcp/tcp_send.c
@@ -366,6 +366,10 @@ static void tcp_sendcommon(FAR struct net_driver_s *dev,
 
       tcp->wnd[0] = recvwndo >> 8;
       tcp->wnd[1] = recvwndo & 0xff;
+
+      /* Update the Receiver Window */
+
+      conn->rcv_wnd = recvwndo;
     }
 
   /* Finish the IP portion of the message and calculate checksums */