NAT44: improve expired sessions reuse (VPP-1503)

[vpp.git] / src / plugins / nat / nat.c

diff --git a/src/plugins/nat/nat.c b/src/plugins/nat/nat.c
index e7d59f7..b7ade88 100755 (executable)
--- a/src/plugins/nat/nat.c
+++ b/src/plugins/nat/nat.c
@@ -397,64 +397,67 @@ nat_ed_session_alloc (snat_main_t * sm, snat_user_t * u, u32 thread_index,
   u32 oldest_index;
   u64 sess_timeout_time;
 
-  if ((u->nsessions + u->nstaticsessions) >= sm->max_translations_per_user)
+  if (PREDICT_FALSE (!(u->nsessions) && !(u->nstaticsessions)))
+    goto alloc_new;
+
+  oldest_index =
+    clib_dlist_remove_head (tsm->list_pool,
+                           u->sessions_per_user_list_head_index);
+  oldest_elt = pool_elt_at_index (tsm->list_pool, oldest_index);
+  s = pool_elt_at_index (tsm->sessions, oldest_elt->value);
+  sess_timeout_time = s->last_heard + (f64) nat44_session_get_timeout (sm, s);
+  if (now >= sess_timeout_time)
     {
-      oldest_index =
-       clib_dlist_remove_head (tsm->list_pool,
-                               u->sessions_per_user_list_head_index);
-      oldest_elt = pool_elt_at_index (tsm->list_pool, oldest_index);
-      s = pool_elt_at_index (tsm->sessions, oldest_elt->value);
-      sess_timeout_time =
-       s->last_heard + (f64) nat44_session_get_timeout (sm, s);
-      if (now >= sess_timeout_time)
-       {
-         clib_dlist_addtail (tsm->list_pool,
-                             u->sessions_per_user_list_head_index,
-                             oldest_index);
-         nat_free_session_data (sm, s, thread_index);
-         if (snat_is_session_static (s))
-           u->nstaticsessions--;
-         else
-           u->nsessions--;
-         s->flags = 0;
-         s->total_bytes = 0;
-         s->total_pkts = 0;
-         s->state = 0;
-         s->ext_host_addr.as_u32 = 0;
-         s->ext_host_port = 0;
-         s->ext_host_nat_addr.as_u32 = 0;
-         s->ext_host_nat_port = 0;
-       }
+      clib_dlist_addtail (tsm->list_pool,
+                         u->sessions_per_user_list_head_index, oldest_index);
+      nat_free_session_data (sm, s, thread_index);
+      if (snat_is_session_static (s))
+       u->nstaticsessions--;
       else
+       u->nsessions--;
+      s->flags = 0;
+      s->total_bytes = 0;
+      s->total_pkts = 0;
+      s->state = 0;
+      s->ext_host_addr.as_u32 = 0;
+      s->ext_host_port = 0;
+      s->ext_host_nat_addr.as_u32 = 0;
+      s->ext_host_nat_port = 0;
+    }
+  else
+    {
+      clib_dlist_addhead (tsm->list_pool,
+                         u->sessions_per_user_list_head_index, oldest_index);
+      if ((u->nsessions + u->nstaticsessions) >=
+         sm->max_translations_per_user)
        {
-         clib_dlist_addhead (tsm->list_pool,
-                             u->sessions_per_user_list_head_index,
-                             oldest_index);
          nat_log_warn ("max translations per user %U", format_ip4_address,
                        &u->addr);
          snat_ipfix_logging_max_entries_per_user
            (sm->max_translations_per_user, u->addr.as_u32);
          return 0;
        }
-    }
-  else
-    {
-      pool_get (tsm->sessions, s);
-      clib_memset (s, 0, sizeof (*s));
+      else
+       {
+       alloc_new:
+         pool_get (tsm->sessions, s);
+         clib_memset (s, 0, sizeof (*s));
 
-      /* Create list elts */
-      pool_get (tsm->list_pool, per_user_translation_list_elt);
-      clib_dlist_init (tsm->list_pool,
-                      per_user_translation_list_elt - tsm->list_pool);
+         /* Create list elts */
+         pool_get (tsm->list_pool, per_user_translation_list_elt);
+         clib_dlist_init (tsm->list_pool,
+                          per_user_translation_list_elt - tsm->list_pool);
 
-      per_user_translation_list_elt->value = s - tsm->sessions;
-      s->per_user_index = per_user_translation_list_elt - tsm->list_pool;
-      s->per_user_list_head_index = u->sessions_per_user_list_head_index;
+         per_user_translation_list_elt->value = s - tsm->sessions;
+         s->per_user_index = per_user_translation_list_elt - tsm->list_pool;
+         s->per_user_list_head_index = u->sessions_per_user_list_head_index;
 
-      clib_dlist_addtail (tsm->list_pool,
-                         s->per_user_list_head_index,
-                         per_user_translation_list_elt - tsm->list_pool);
+         clib_dlist_addtail (tsm->list_pool,
+                             s->per_user_list_head_index,
+                             per_user_translation_list_elt - tsm->list_pool);
+       }
     }
+
   return s;
 }