session: allow closed transports to send

Type:fix

Transports like tcp may notify session layer of a close but they may
defer the connection's deletion (e.g., tcp time-wait). During that time,
transports may still want to send packets. So, unless the session has no
transport (transport-deleted state), allow the transport to send.

Change-Id: I3ae335c7b951ff64be8529a5e3f3ad790feddc84
Signed-off-by: Florin Coras <fcoras@cisco.com>

diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index c2e3dd0..5af54a8 100644 (file)
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -512,12 +512,21 @@ session_tx_not_ready (session_t * s, u8 peek_data)
 {
   if (peek_data)
     {
+      if (PREDICT_TRUE (s->session_state == SESSION_STATE_READY))
+       return 0;
       /* Can retransmit for closed sessions but can't send new data if
        * session is not ready or closed */
-      if (s->session_state < SESSION_STATE_READY)
+      else if (s->session_state < SESSION_STATE_READY)
        return 1;
-      if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED)
-       return 2;
+      else if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED)
+       {
+         /* Allow closed transports to still send custom packets.
+          * For instance, tcp may want to send acks in time-wait. */
+         if (s->session_state != SESSION_STATE_TRANSPORT_DELETED
+             && (s->flags & SESSION_F_CUSTOM_TX))
+           return 0;
+         return 2;
+       }
     }
   return 0;
 }
@@ -639,7 +648,6 @@ session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
   tp = session_get_transport_proto (ctx->s);
   ctx->transport_vft = transport_protocol_get_vft (tp);
   ctx->tc = session_tx_get_transport (ctx, peek_data);
-  ctx->snd_mss = ctx->transport_vft->send_mss (ctx->tc);
 
   if (PREDICT_FALSE (e->event_type == SESSION_IO_EVT_TX_FLUSH))
     {
@@ -653,6 +661,9 @@ session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
       ctx->s->flags &= ~SESSION_F_CUSTOM_TX;
       n_custom_tx = ctx->transport_vft->custom_tx (ctx->tc, max_burst);
       *n_tx_packets += n_custom_tx;
+      if (PREDICT_FALSE
+         (ctx->s->session_state >= SESSION_STATE_TRANSPORT_CLOSED))
+       return SESSION_TX_OK;
       max_burst -= n_custom_tx;
       if (!max_burst)
        {
@@ -661,6 +672,7 @@ session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
        }
     }
 
+  ctx->snd_mss = ctx->transport_vft->send_mss (ctx->tc);
   ctx->snd_space = transport_connection_snd_space (ctx->tc,
                                                   vm->clib_time.
                                                   last_cpu_time,