nat: sessions get expired when fib table removed

fib table removal would leave lingering sessions in vpp
this patch is aimed at solving this issue by grouping
sessions by source and destionation fib. if one of the
fibs gets removed this grouping is tagged as expired
and session won't be passed to non existing fib table

Ticket: VPPSUPP-93
Type: improvement

Change-Id: I45b1205a8b58d91f174e6feb862554ec2f6cffad
Signed-off-by: Filip Varga <fivarga@cisco.com>

1 files changed, 111 insertions, 0 deletions

diff --git a/src/plugins/nat/nat44/ed_inlines.h b/src/plugins/nat/nat44/ed_inlines.h
index 37212f36bf5..1b4df4d02fd 100644
--- a/src/plugins/nat/nat44/ed_inlines.h
+++ b/src/plugins/nat/nat44/ed_inlines.h
@@ -141,4 +141,115 @@ nat_ed_session_alloc (snat_main_t * sm, u32 thread_index, f64 now, u8 proto)
   return s;
 }
 
+// slow path
+static_always_inline void
+per_vrf_sessions_cleanup (u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm =
+    vec_elt_at_index (sm->per_thread_data, thread_index);
+  per_vrf_sessions_t *per_vrf_sessions;
+  u32 *to_free = 0, *i;
+
+  vec_foreach (per_vrf_sessions, tsm->per_vrf_sessions_vec)
+  {
+    if (per_vrf_sessions->expired)
+      {
+	if (per_vrf_sessions->ses_count == 0)
+	  {
+	    vec_add1 (to_free, per_vrf_sessions - tsm->per_vrf_sessions_vec);
+	  }
+      }
+  }
+
+  if (vec_len (to_free))
+    {
+      vec_foreach (i, to_free)
+      {
+	vec_del1 (tsm->per_vrf_sessions_vec, *i);
+      }
+    }
+
+  vec_free (to_free);
+}
+
+// slow path
+static_always_inline void
+per_vrf_sessions_register_session (snat_session_t * s, u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm =
+    vec_elt_at_index (sm->per_thread_data, thread_index);
+  per_vrf_sessions_t *per_vrf_sessions;
+
+  per_vrf_sessions_cleanup (thread_index);
+
+  // s->per_vrf_sessions_index == ~0 ... reuse of old session
+
+  vec_foreach (per_vrf_sessions, tsm->per_vrf_sessions_vec)
+  {
+    // ignore already expired registrations
+    if (per_vrf_sessions->expired)
+      continue;
+
+    if ((s->in2out.fib_index == per_vrf_sessions->rx_fib_index) &&
+	(s->out2in.fib_index == per_vrf_sessions->tx_fib_index))
+      {
+	goto done;
+      }
+    if ((s->in2out.fib_index == per_vrf_sessions->tx_fib_index) &&
+	(s->out2in.fib_index == per_vrf_sessions->rx_fib_index))
+      {
+	goto done;
+      }
+  }
+
+  // create a new registration
+  vec_add2 (tsm->per_vrf_sessions_vec, per_vrf_sessions, 1);
+  clib_memset (per_vrf_sessions, 0, sizeof (*per_vrf_sessions));
+
+  per_vrf_sessions->rx_fib_index = s->in2out.fib_index;
+  per_vrf_sessions->tx_fib_index = s->out2in.fib_index;
+
+done:
+  s->per_vrf_sessions_index = per_vrf_sessions - tsm->per_vrf_sessions_vec;
+  per_vrf_sessions->ses_count++;
+}
+
+// fast path
+static_always_inline void
+per_vrf_sessions_unregister_session (snat_session_t * s, u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+  per_vrf_sessions_t *per_vrf_sessions;
+
+  ASSERT (s->per_vrf_sessions_index != ~0);
+  
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+  per_vrf_sessions = vec_elt_at_index (tsm->per_vrf_sessions_vec,
+                                       s->per_vrf_sessions_index);
+
+  ASSERT (per_vrf_sessions->ses_count != 0);
+
+  per_vrf_sessions->ses_count--;
+  s->per_vrf_sessions_index = ~0;
+}
+
+// fast path
+static_always_inline u8
+per_vrf_sessions_is_expired (snat_session_t * s, u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+  per_vrf_sessions_t *per_vrf_sessions;
+
+  ASSERT (s->per_vrf_sessions_index != ~0);
+
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+  per_vrf_sessions = vec_elt_at_index (tsm->per_vrf_sessions_vec,
+                                       s->per_vrf_sessions_index);
+  return per_vrf_sessions->expired;
+}
+
 #endif