commit 81cb8e4092991d3fd1e24f0862c12548a2d4c714
author Florin Coras <fcoras@cisco.com> Tue Oct 22 19:44:45 2019 -0700
committer Damjan Marion <dmarion@me.com> Wed Oct 23 07:45:00 2019 +0000
tree f5d6470fec183a9738d534db9837c9929a002eb5
parent 386ebb6e2baa7d3b2535d646c04ccf852f859869

tcp: fix sack retransmit beyond snd_nxt

Type: fix

Ensure that sack retransmit logic does not try to inadvertently send new
data.

Change-Id: Idfda19643577d9c1b58e2af8d8283cabfbaf98e6
Signed-off-by: Florin Coras <fcoras@cisco.com>

src/vnet/tcp/tcp_output.c

diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index e3228c0..0047f3c 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -1392,6 +1392,8 @@
   max_deq_bytes = clib_min (available_bytes, max_deq_bytes);
 
   start = tc->snd_una + offset;
+  ASSERT (seq_leq (start + max_deq_bytes, tc->snd_nxt));
+
   n_bytes = tcp_prepare_segment (wrk, tc, offset, max_deq_bytes, b);
   if (!n_bytes)
     return 0;
@@ -1521,7 +1523,8 @@
 
       /* Send the first unacked segment. If we're short on buffers, return
        * as soon as possible */
-      n_bytes = tcp_prepare_retransmit_segment (wrk, tc, 0, tc->snd_mss, &b);
+      n_bytes = clib_min (tc->snd_mss, tc->snd_nxt - tc->snd_una);
+      n_bytes = tcp_prepare_retransmit_segment (wrk, tc, 0, n_bytes, &b);
       if (!n_bytes)
 	{
 	  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT, 1);
@@ -1922,7 +1925,7 @@
 
   while (snd_space > 0 && n_segs < burst_size)
     {
-      hole = scoreboard_next_rxt_hole (sb, hole, max_deq, &can_rescue,
+      hole = scoreboard_next_rxt_hole (sb, hole, max_deq != 0, &can_rescue,
 				       &snd_limited);
       if (!hole)
 	{
@@ -1990,6 +1993,8 @@
       tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
 
       sb->high_rxt += n_written;
+      ASSERT (seq_leq (sb->high_rxt, tc->snd_nxt));
+
       snd_space -= n_written;
       n_segs += 1;
     }