From: Florin Coras <fcoras@cisco.com>
Date: Sat, 14 Oct 2023 22:16:18 +0000 (-0700)
Subject: tcp: allow fins in syns in syn-rcvd
X-Git-Tag: v24.06-rc0~209
X-Git-Url: https://gerrit.fd.io/r/gitweb?p=vpp.git;a=commitdiff_plain;h=da2ae9af61fbdb3b68eb72f8d35294fdb3720303

tcp: allow fins in syns in syn-rcvd

Also make sure connection is properly cleaned up.

Type: fix

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I02f83e9a1e17cbbbd2ee74044d02049b2fd2f21c
---

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 1602b49b910..1494fd84b6b 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -2123,7 +2123,7 @@ tcp46_rcv_process_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 	case TCP_STATE_SYN_RCVD:
 
 	  /* Make sure the segment is exactly right */
-	  if (tc->rcv_nxt != vnet_buffer (b[0])->tcp.seq_number || is_fin)
+	  if (tc->rcv_nxt != vnet_buffer (b[0])->tcp.seq_number)
 	    {
 	      tcp_send_reset_w_pkt (tc, b[0], thread_index, is_ip4);
 	      error = TCP_ERROR_SEGMENT_INVALID;
@@ -2143,6 +2143,10 @@ tcp46_rcv_process_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 	      goto drop;
 	    }
 
+	  /* Avoid notifying app if connection is about to be closed */
+	  if (PREDICT_FALSE (is_fin))
+	    break;
+
 	  /* Update rtt and rto */
 	  tcp_estimate_initial_rtt (tc);
 	  tcp_connection_tx_pacer_update (tc);
@@ -2363,15 +2367,15 @@ tcp46_rcv_process_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 			    tcp_cfg.closewait_time);
 	  break;
 	case TCP_STATE_SYN_RCVD:
-	  /* Send FIN-ACK, enter LAST-ACK and because the app was not
-	   * notified yet, set a cleanup timer instead of relying on
-	   * disconnect notify and the implicit close call. */
+	  /* Send FIN-ACK and enter TIME-WAIT, as opposed to LAST-ACK,
+	   * because the app was not notified yet and we want to avoid
+	   * session state transitions to ensure cleanup does not
+	   * propagate to app. */
 	  tcp_connection_timers_reset (tc);
 	  tc->rcv_nxt += 1;
 	  tcp_send_fin (tc);
-	  tcp_connection_set_state (tc, TCP_STATE_LAST_ACK);
-	  tcp_timer_set (&wrk->timer_wheel, tc, TCP_TIMER_WAITCLOSE,
-			 tcp_cfg.lastack_time);
+	  tcp_connection_set_state (tc, TCP_STATE_TIME_WAIT);
+	  tcp_program_cleanup (wrk, tc);
 	  break;
 	case TCP_STATE_CLOSE_WAIT:
 	case TCP_STATE_CLOSING: