tcp: fix retransmit with no sacks

Type: fix

Change-Id: I6f7df0d358f57f7feadb9b7a3fcffb99558b2af8
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 4b0a0dd..f403887 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -882,7 +882,8 @@
   if (tcp_opts_sack_permitted (&tc->rcv_opts))
     return tc->sack_sb.sacked_bytes + tc->sack_sb.lost_bytes;
   else
-    return tc->rcv_dupacks * tc->snd_mss;
+    return clib_min (tc->rcv_dupacks * tc->snd_mss,
+		     tc->snd_nxt - tc->snd_una);
 }
 
 /**