From 18ab274af32dd0e8410fb0b5e13f841da57545db Mon Sep 17 00:00:00 2001
From: goldsimon <goldsimon>
Date: Thu, 22 Oct 2009 13:37:44 +0000
Subject: [PATCH] Fixed bug #26251: RST process in TIME_WAIT TCP state

---
 CHANGELOG         |  3 +++
 src/core/tcp_in.c | 12 ++++++------
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 861423f5..b2a12a43 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -43,6 +43,9 @@ HISTORY
 
   ++ Bugfixes:
 
+  2009-10-22: Simon Goldschmidt
+  * tcp_in.c: Fixed bug #26251: RST process in TIME_WAIT TCP state
+
   2009-10-21: Simon Goldschmidt
   * tcp_in.c: Fixed bug #27215: TCP sent() callback gives leading and
     trailing 1 byte len (SYN/FIN)
diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index 5fcb4cac..febafff0 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -480,13 +480,13 @@ tcp_listen_input(struct tcp_pcb_listen *pcb)
 static err_t
 tcp_timewait_input(struct tcp_pcb *pcb)
 {
-  if (TCP_SEQ_GT(seqno + tcplen, pcb->rcv_nxt)) {
-    pcb->rcv_nxt = seqno + tcplen;
+  u16_t flags = TCPH_FLAGS(tcphdr);
+  /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
+  if (((flags & TCP_RST) == 0) && ((flags & TCP_FIN) || (tcplen > 0)))  {
+    pcb->flags |= TF_ACK_NOW;
+    return tcp_output(pcb);
   }
-  if (tcplen > 0) {
-    tcp_ack_now(pcb);
-  }
-  return tcp_output(pcb);
+  return ERR_OK;
 }
 
 /**