From ac638c85f3c204b55bd35123e2df884ecd252d77 Mon Sep 17 00:00:00 2001
From: goldsimon <goldsimon>
Date: Sun, 11 Oct 2009 13:06:44 +0000
Subject: [PATCH] Fixed bug #27504: tcp_enqueue wrongly concatenates segments
 which are not consecutive when retransmitting unacked segments

---
 CHANGELOG          | 4 ++++
 src/core/tcp_out.c | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG b/CHANGELOG
index 045ccffe..c8513d5f 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -43,6 +43,10 @@ HISTORY
 
   ++ Bugfixes:
 
+  2009-10-11 Simon Goldschmidt (Jörg Kesten)
+  * tcp_out.c: Fixed bug #27504: tcp_enqueue wrongly concatenates segments
+    which are not consecutive when retransmitting unacked segments
+
   2009-10-09 Simon Goldschmidt
   * opt.h: Fixed default values of some stats to only be enabled if used
     Fixes bug #27338: sys_stats is defined when NO_SYS = 1
diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index ca72d9dc..bef38b26 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -347,7 +347,9 @@ tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
     /* fit within max seg size */
     (useg->len + queue->len <= pcb->mss) &&
     /* only concatenate segments with the same options */
-    (useg->flags == queue->flags)) {
+    (useg->flags == queue->flags) &&
+    /* segments are consecutive */
+    (ntohl(useg->tcphdr->seqno) + useg->len == ntohl(queue->tcphdr->seqno)) ) {
     /* Remove TCP header from first segment of our to-be-queued list */
     if(pbuf_header(queue->p, -(TCP_HLEN + optlen))) {
       /* Can we cope with this failing?  Just assert for now */