NAT44: active-passive HA (VPP-1571)
[vpp.git] / src / plugins / nat / nat.c
index c2c812d..3856add 100755 (executable)
@@ -30,6 +30,7 @@
 #include <nat/nat_inlines.h>
 #include <nat/nat_affinity.h>
 #include <nat/nat_syslog.h>
+#include <nat/nat_ha.h>
 #include <vnet/fib/fib_table.h>
 #include <vnet/fib/ip4_fib.h>
 
@@ -175,7 +176,8 @@ VLIB_PLUGIN_REGISTER () = {
 /* *INDENT-ON* */
 
 void
-nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index)
+nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index,
+                      u8 is_ha)
 {
   snat_session_key_t key;
   clib_bihash_kv_8_8_t kv;
@@ -238,12 +240,13 @@ nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index)
       if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &ed_kv, 0))
        nat_log_warn ("in2out_ed key del failed");
 
-      nat_syslog_nat44_sdel (s->user_index, s->in2out.fib_index,
-                            &s->in2out.addr, s->in2out.port,
-                            &s->ext_host_nat_addr, s->ext_host_nat_port,
-                            &s->out2in.addr, s->out2in.port,
-                            &s->ext_host_addr, s->ext_host_port,
-                            s->in2out.protocol, is_twice_nat_session (s));
+      if (!is_ha)
+       nat_syslog_nat44_sdel (s->user_index, s->in2out.fib_index,
+                              &s->in2out.addr, s->in2out.port,
+                              &s->ext_host_nat_addr, s->ext_host_nat_port,
+                              &s->out2in.addr, s->out2in.port,
+                              &s->ext_host_addr, s->ext_host_port,
+                              s->in2out.protocol, is_twice_nat_session (s));
     }
   else
     {
@@ -254,21 +257,31 @@ nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index)
       if (clib_bihash_add_del_8_8 (&tsm->out2in, &kv, 0))
        nat_log_warn ("out2in key del failed");
 
-      nat_syslog_nat44_apmdel (s->user_index, s->in2out.fib_index,
-                              &s->in2out.addr, s->in2out.port,
-                              &s->out2in.addr, s->out2in.port,
-                              s->in2out.protocol);
+      if (!is_ha)
+       nat_syslog_nat44_apmdel (s->user_index, s->in2out.fib_index,
+                                &s->in2out.addr, s->in2out.port,
+                                &s->out2in.addr, s->out2in.port,
+                                s->in2out.protocol);
     }
 
   if (snat_is_unk_proto_session (s))
     return;
 
-  /* log NAT event */
-  snat_ipfix_logging_nat44_ses_delete (s->in2out.addr.as_u32,
-                                      s->out2in.addr.as_u32,
-                                      s->in2out.protocol,
-                                      s->in2out.port,
-                                      s->out2in.port, s->in2out.fib_index);
+  if (!is_ha)
+    {
+      /* log NAT event */
+      snat_ipfix_logging_nat44_ses_delete (thread_index,
+                                          s->in2out.addr.as_u32,
+                                          s->out2in.addr.as_u32,
+                                          s->in2out.protocol,
+                                          s->in2out.port,
+                                          s->out2in.port,
+                                          s->in2out.fib_index);
+
+      nat_ha_sdel (&s->out2in.addr, s->out2in.port, &s->ext_host_addr,
+                  s->ext_host_port, s->out2in.protocol, s->out2in.fib_index,
+                  thread_index);
+    }
 
   /* Twice NAT address and port for external host */
   if (is_twice_nat_session (s))
@@ -336,7 +349,7 @@ nat_user_get_or_create (snat_main_t * sm, ip4_address_t * addr, u32 fib_index,
 
 snat_session_t *
 nat_session_alloc_or_recycle (snat_main_t * sm, snat_user_t * u,
-                             u32 thread_index)
+                             u32 thread_index, f64 now)
 {
   snat_session_t *s;
   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
@@ -367,7 +380,7 @@ nat_session_alloc_or_recycle (snat_main_t * sm, snat_user_t * u,
 
       /* Get the session */
       s = pool_elt_at_index (tsm->sessions, session_index);
-      nat_free_session_data (sm, s, thread_index);
+      nat_free_session_data (sm, s, thread_index, 0);
       if (snat_is_session_static (s))
        u->nstaticsessions--;
       else
@@ -404,6 +417,8 @@ nat_session_alloc_or_recycle (snat_main_t * sm, snat_user_t * u,
                               pool_elts (tsm->sessions));
     }
 
+  s->ha_last_refreshed = now;
+
   return s;
 }
 
@@ -430,7 +445,7 @@ nat_ed_session_alloc (snat_main_t * sm, snat_user_t * u, u32 thread_index,
     {
       clib_dlist_addtail (tsm->list_pool,
                          u->sessions_per_user_list_head_index, oldest_index);
-      nat_free_session_data (sm, s, thread_index);
+      nat_free_session_data (sm, s, thread_index, 0);
       if (snat_is_session_static (s))
        u->nstaticsessions--;
       else
@@ -454,7 +469,7 @@ nat_ed_session_alloc (snat_main_t * sm, snat_user_t * u, u32 thread_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);
+           (thread_index, sm->max_translations_per_user, u->addr.as_u32);
          return 0;
        }
       else
@@ -481,6 +496,8 @@ nat_ed_session_alloc (snat_main_t * sm, snat_user_t * u, u32 thread_index,
                               pool_elts (tsm->sessions));
     }
 
+  s->ha_last_refreshed = now;
+
   return s;
 }
 
@@ -962,7 +979,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
                        continue;
 
                      nat_free_session_data (sm, s,
-                                            tsm - sm->per_thread_data);
+                                            tsm - sm->per_thread_data, 0);
                      nat44_delete_session (sm, s, tsm - sm->per_thread_data);
 
                      if (!addr_only && !sm->endpoint_dependent)
@@ -1086,7 +1103,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
                        continue;
 
                      nat_free_session_data (sm, s,
-                                            tsm - sm->per_thread_data);
+                                            tsm - sm->per_thread_data, 0);
                      nat44_delete_session (sm, s, tsm - sm->per_thread_data);
 
                      if (!addr_only && !sm->endpoint_dependent)
@@ -1395,7 +1412,7 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
                           (clib_net_to_host_u16 (s->in2out.port) != local->port))
                         continue;
 
-                      nat_free_session_data (sm, s, tsm - sm->per_thread_data);
+                      nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
                       nat44_delete_session (sm, s, tsm - sm->per_thread_data);
                     }
                 }
@@ -1549,7 +1566,7 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
                       match_local->port))
                    continue;
 
-                 nat_free_session_data (sm, s, tsm - sm->per_thread_data);
+                 nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
                  nat44_delete_session (sm, s, tsm - sm->per_thread_data);
                }
            }
@@ -1575,6 +1592,8 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
   }));
   /* *INDENT-ON* */
 
+  ASSERT (vec_len (locals) > 1);
+
   local = pool_elt_at_index (m->locals, locals[0]);
   local->prefix = local->probability;
   for (i = 1; i < vec_len (locals); i++)
@@ -1657,7 +1676,7 @@ snat_del_address (snat_main_t * sm, ip4_address_t addr, u8 delete_sm,
           pool_foreach (ses, tsm->sessions, ({
             if (ses->out2in.addr.as_u32 == addr.as_u32)
               {
-                nat_free_session_data (sm, ses, tsm - sm->per_thread_data);
+                nat_free_session_data (sm, ses, tsm - sm->per_thread_data, 0);
                 vec_add1 (ses_to_be_removed, ses - tsm->sessions);
               }
           }));
@@ -1766,7 +1785,7 @@ snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
             {
               if (is_del)
                 {
-                  outside_fib->refcount--;
+                 outside_fib->refcount--;
                   if (!outside_fib->refcount)
                     vec_del1 (sm->outside_fibs, outside_fib - sm->outside_fibs);
                 }
@@ -1966,6 +1985,10 @@ snat_interface_add_del_output_feature (u32 sw_if_index,
   snat_interface_t *i;
   snat_address_t *ap;
   snat_static_mapping_t *m;
+  nat_outside_fib_t *outside_fib;
+  u32 fib_index = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
+                                                      sw_if_index);
+
 
   if (sm->deterministic ||
       (sm->static_mapping_only && !(sm->static_mapping_connection_tracking)))
@@ -1979,6 +2002,34 @@ snat_interface_add_del_output_feature (u32 sw_if_index,
   }));
   /* *INDENT-ON* */
 
+  if (!is_inside)
+    {
+      /* *INDENT-OFF* */
+      vec_foreach (outside_fib, sm->outside_fibs)
+        {
+          if (outside_fib->fib_index == fib_index)
+            {
+              if (is_del)
+                {
+                 outside_fib->refcount--;
+                  if (!outside_fib->refcount)
+                    vec_del1 (sm->outside_fibs, outside_fib - sm->outside_fibs);
+                }
+              else
+                outside_fib->refcount++;
+              goto feature_set;
+            }
+        }
+      /* *INDENT-ON* */
+      if (!is_del)
+       {
+         vec_add2 (sm->outside_fibs, outside_fib, 1);
+         outside_fib->refcount = 1;
+         outside_fib->fib_index = fib_index;
+       }
+    }
+
+feature_set:
   if (is_inside)
     {
       if (sm->endpoint_dependent)
@@ -2109,6 +2160,65 @@ snat_set_workers (uword * bitmap)
   return 0;
 }
 
+static void
+snat_update_outside_fib (u32 sw_if_index, u32 new_fib_index,
+                        u32 old_fib_index)
+{
+  snat_main_t *sm = &snat_main;
+  nat_outside_fib_t *outside_fib;
+  snat_interface_t *i;
+  u8 is_add = 1;
+
+  if (new_fib_index == old_fib_index)
+    return;
+
+  if (!vec_len (sm->outside_fibs))
+    return;
+
+  pool_foreach (i, sm->interfaces, (
+                                    {
+                                    if (i->sw_if_index == sw_if_index)
+                                    {
+                                    if (!(nat_interface_is_outside (i)))
+                                    return;}
+                                    }
+               ));
+  vec_foreach (outside_fib, sm->outside_fibs)
+  {
+    if (outside_fib->fib_index == old_fib_index)
+      {
+       outside_fib->refcount--;
+       if (!outside_fib->refcount)
+         vec_del1 (sm->outside_fibs, outside_fib - sm->outside_fibs);
+       break;
+      }
+  }
+
+  vec_foreach (outside_fib, sm->outside_fibs)
+  {
+    if (outside_fib->fib_index == new_fib_index)
+      {
+       outside_fib->refcount++;
+       is_add = 0;
+       break;
+      }
+  }
+
+  if (is_add)
+    {
+      vec_add2 (sm->outside_fibs, outside_fib, 1);
+      outside_fib->refcount = 1;
+      outside_fib->fib_index = new_fib_index;
+    }
+}
+
+static void
+snat_ip4_table_bind (ip4_main_t * im,
+                    uword opaque,
+                    u32 sw_if_index, u32 new_fib_index, u32 old_fib_index)
+{
+  snat_update_outside_fib (sw_if_index, new_fib_index, old_fib_index);
+}
 
 static void
 snat_ip4_add_del_interface_address_cb (ip4_main_t * im,
@@ -2146,7 +2256,7 @@ snat_init (vlib_main_t * vm)
   uword *bitmap = 0;
   u32 i;
   ip4_add_del_interface_address_callback_t cb4;
-  vlib_node_t *error_drop_node;
+  vlib_node_t *node;
 
   sm->vlib_main = vm;
   sm->vnet_main = vnet_get_main ();
@@ -2168,10 +2278,63 @@ snat_init (vlib_main_t * vm)
   sm->addr_and_port_alloc_alg = NAT_ADDR_AND_PORT_ALLOC_ALG_DEFAULT;
   sm->forwarding_enabled = 0;
   sm->log_class = vlib_log_register_class ("nat", 0);
-  error_drop_node = vlib_get_node_by_name (vm, (u8 *) "error-drop");
-  sm->error_node_index = error_drop_node->index;
   sm->mss_clamping = 0;
 
+  node = vlib_get_node_by_name (vm, (u8 *) "error-drop");
+  sm->error_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out");
+  sm->in2out_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-output");
+  sm->in2out_output_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-fast");
+  sm->in2out_fast_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-slowpath");
+  sm->in2out_slowpath_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-output-slowpath");
+  sm->in2out_slowpath_output_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-reass");
+  sm->in2out_reass_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out");
+  sm->ed_in2out_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out-slowpath");
+  sm->ed_in2out_slowpath_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out-reass");
+  sm->ed_in2out_reass_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-out2in");
+  sm->out2in_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-out2in-fast");
+  sm->out2in_fast_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-out2in-reass");
+  sm->out2in_reass_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-out2in");
+  sm->ed_out2in_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-out2in-slowpath");
+  sm->ed_out2in_slowpath_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-out2in-reass");
+  sm->ed_out2in_reass_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-det-in2out");
+  sm->det_in2out_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-det-out2in");
+  sm->det_out2in_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-hairpinning");
+  sm->hairpinning_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-hairpin-dst");
+  sm->hairpin_dst_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-hairpin-src");
+  sm->hairpin_src_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-hairpinning");
+  sm->ed_hairpinning_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-hairpin-dst");
+  sm->ed_hairpin_dst_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-hairpin-src");
+  sm->ed_hairpin_src_node_index = node->index;
+
   p = hash_get_mem (tm->thread_registrations_by_name, "workers");
   if (p)
     {
@@ -2235,7 +2398,12 @@ snat_init (vlib_main_t * vm)
 
   dslite_init (vm);
 
-  nat66_init ();
+  nat66_init (vm);
+
+  ip4_table_bind_callback_t cbt4 = {
+    .function = snat_ip4_table_bind,
+  };
+  vec_add1 (ip4_main.table_bind_callbacks, cbt4);
 
   /* Init virtual fragmenentation reassembly */
   return nat_reass_init (vm);
@@ -2281,6 +2449,42 @@ snat_free_outside_address_and_port (snat_address_t * addresses,
     }
 }
 
+static int
+nat_set_outside_address_and_port (snat_address_t * addresses,
+                                 u32 thread_index, snat_session_key_t * k)
+{
+  snat_address_t *a = 0;
+  u32 address_index;
+  u16 port_host_byte_order = clib_net_to_host_u16 (k->port);
+
+  for (address_index = 0; address_index < vec_len (addresses);
+       address_index++)
+    {
+      if (addresses[address_index].addr.as_u32 != k->addr.as_u32)
+       continue;
+
+      a = addresses + address_index;
+      switch (k->protocol)
+       {
+#define _(N, j, n, s) \
+        case SNAT_PROTOCOL_##N: \
+          if (clib_bitmap_get_no_check (a->busy_##n##_port_bitmap, port_host_byte_order)) \
+            return VNET_API_ERROR_INSTANCE_IN_USE; \
+          clib_bitmap_set_no_check (a->busy_##n##_port_bitmap, port_host_byte_order, 1); \
+          a->busy_##n##_ports_per_thread[thread_index]++; \
+          a->busy_##n##_ports++; \
+          return 0;
+         foreach_snat_protocol
+#undef _
+       default:
+         nat_log_info ("unknown protocol");
+         return 1;
+       }
+    }
+
+  return VNET_API_ERROR_NO_SUCH_ENTRY;
+}
+
 int
 snat_static_mapping_match (snat_main_t * sm,
                           snat_session_key_t match,
@@ -2523,7 +2727,7 @@ nat_alloc_addr_and_port_default (snat_address_t * addresses,
     }
 
   /* Totally out of translations to use... */
-  snat_ipfix_logging_addresses_exhausted (0);
+  snat_ipfix_logging_addresses_exhausted (thread_index, 0);
   return 1;
 }
 
@@ -2573,7 +2777,7 @@ nat_alloc_addr_and_port_mape (snat_address_t * addresses,
 
 exhausted:
   /* Totally out of translations to use... */
-  snat_ipfix_logging_addresses_exhausted (0);
+  snat_ipfix_logging_addresses_exhausted (thread_index, 0);
   return 1;
 }
 
@@ -2621,7 +2825,7 @@ nat_alloc_addr_and_port_range (snat_address_t * addresses,
 
 exhausted:
   /* Totally out of translations to use... */
-  snat_ipfix_logging_addresses_exhausted (0);
+  snat_ipfix_logging_addresses_exhausted (thread_index, 0);
   return 1;
 }
 
@@ -2763,20 +2967,47 @@ snat_get_worker_out2in_cb (ip4_header_t * ip0, u32 rx_fib_index0)
       if (PREDICT_FALSE (nat_reass_is_drop_frag (0)))
        return vlib_get_thread_index ();
 
-      if (PREDICT_TRUE (!ip4_is_first_fragment (ip0)))
-       {
-         nat_reass_ip4_t *reass;
+      nat_reass_ip4_t *reass;
+      reass = nat_ip4_reass_find (ip0->src_address, ip0->dst_address,
+                                 ip0->fragment_id, ip0->protocol);
 
-         reass = nat_ip4_reass_find (ip0->src_address, ip0->dst_address,
-                                     ip0->fragment_id, ip0->protocol);
+      if (reass && (reass->thread_index != (u32) ~ 0))
+       return reass->thread_index;
 
-         if (reass && (reass->thread_index != (u32) ~ 0))
-           return reass->thread_index;
-         else
-           return vlib_get_thread_index ();
+      if (ip4_is_first_fragment (ip0))
+       {
+         reass =
+           nat_ip4_reass_create (ip0->src_address, ip0->dst_address,
+                                 ip0->fragment_id, ip0->protocol);
+         if (!reass)
+           goto no_reass;
+
+         if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
+           {
+             m_key.addr = ip0->dst_address;
+             m_key.port = clib_net_to_host_u16 (port);
+             m_key.protocol = proto;
+             m_key.fib_index = rx_fib_index0;
+             kv.key = m_key.as_u64;
+             if (!clib_bihash_search_8_8
+                 (&sm->static_mapping_by_external, &kv, &value))
+               {
+                 m = pool_elt_at_index (sm->static_mappings, value.value);
+                 reass->thread_index = m->workers[0];
+                 return reass->thread_index;
+               }
+           }
+         reass->thread_index = sm->first_worker_index;
+         reass->thread_index +=
+           sm->workers[(clib_net_to_host_u16 (port) - 1024) /
+                       sm->port_per_thread];
+         return reass->thread_index;
        }
+      else
+       return vlib_get_thread_index ();
     }
 
+no_reass:
   /* unknown protocol */
   if (PREDICT_FALSE (proto == ~0))
     {
@@ -2928,6 +3159,334 @@ nat44_ed_get_worker_out2in_cb (ip4_header_t * ip, u32 rx_fib_index)
   return next_worker_index;
 }
 
+void
+nat_ha_sadd_cb (ip4_address_t * in_addr, u16 in_port,
+               ip4_address_t * out_addr, u16 out_port,
+               ip4_address_t * eh_addr, u16 eh_port,
+               ip4_address_t * ehn_addr, u16 ehn_port, u8 proto,
+               u32 fib_index, u16 flags, u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_session_key_t key;
+  snat_user_t *u;
+  snat_session_t *s;
+  clib_bihash_kv_8_8_t kv;
+  f64 now = vlib_time_now (sm->vlib_main);
+  nat_outside_fib_t *outside_fib;
+  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
+  snat_main_per_thread_data_t *tsm;
+  fib_prefix_t pfx = {
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_len = 32,
+    .fp_addr = {
+               .ip4.as_u32 = eh_addr->as_u32,
+               },
+  };
+
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+
+  key.addr.as_u32 = out_addr->as_u32;
+  key.port = out_port;
+  key.protocol = proto;
+
+  if (!(flags & SNAT_SESSION_FLAG_STATIC_MAPPING))
+    {
+      if (nat_set_outside_address_and_port
+         (sm->addresses, thread_index, &key))
+       return;
+    }
+
+  u = nat_user_get_or_create (sm, in_addr, fib_index, thread_index);
+  if (!u)
+    return;
+
+  s = nat_session_alloc_or_recycle (sm, u, thread_index, now);
+  if (!s)
+    return;
+
+  s->last_heard = now;
+  s->flags = flags;
+  s->ext_host_addr.as_u32 = eh_addr->as_u32;
+  s->ext_host_port = eh_port;
+  user_session_increment (sm, u, snat_is_session_static (s));
+  switch (vec_len (sm->outside_fibs))
+    {
+    case 0:
+      key.fib_index = sm->outside_fib_index;
+      break;
+    case 1:
+      key.fib_index = sm->outside_fibs[0].fib_index;
+      break;
+    default:
+      /* *INDENT-OFF* */
+      vec_foreach (outside_fib, sm->outside_fibs)
+        {
+          fei = fib_table_lookup (outside_fib->fib_index, &pfx);
+          if (FIB_NODE_INDEX_INVALID != fei)
+            {
+              if (fib_entry_get_resolving_interface (fei) != ~0)
+                {
+                  key.fib_index = outside_fib->fib_index;
+                  break;
+                }
+            }
+        }
+      /* *INDENT-ON* */
+      break;
+    }
+  s->out2in = key;
+  kv.key = key.as_u64;
+  kv.value = s - tsm->sessions;
+  if (clib_bihash_add_del_8_8 (&tsm->out2in, &kv, 1))
+    nat_log_warn ("out2in key add failed");
+
+  key.addr.as_u32 = in_addr->as_u32;
+  key.port = in_port;
+  key.fib_index = fib_index;
+  s->in2out = key;
+  kv.key = key.as_u64;
+  if (clib_bihash_add_del_8_8 (&tsm->in2out, &kv, 1))
+    nat_log_warn ("in2out key add failed");
+}
+
+void
+nat_ha_sdel_cb (ip4_address_t * out_addr, u16 out_port,
+               ip4_address_t * eh_addr, u16 eh_port, u8 proto, u32 fib_index,
+               u32 ti)
+{
+  snat_main_t *sm = &snat_main;
+  snat_session_key_t key;
+  clib_bihash_kv_8_8_t kv, value;
+  u32 thread_index;
+  snat_session_t *s;
+  snat_main_per_thread_data_t *tsm;
+
+  if (sm->num_workers > 1)
+    thread_index =
+      sm->first_worker_index +
+      (sm->workers[(clib_net_to_host_u16 (out_port) -
+                   1024) / sm->port_per_thread]);
+  else
+    thread_index = sm->num_workers;
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+
+  key.addr.as_u32 = out_addr->as_u32;
+  key.port = out_port;
+  key.protocol = proto;
+  key.fib_index = fib_index;
+  kv.key = key.as_u64;
+  if (clib_bihash_search_8_8 (&tsm->out2in, &kv, &value))
+    return;
+
+  s = pool_elt_at_index (tsm->sessions, value.value);
+  nat_free_session_data (sm, s, thread_index, 1);
+  nat44_delete_session (sm, s, thread_index);
+}
+
+void
+nat_ha_sref_cb (ip4_address_t * out_addr, u16 out_port,
+               ip4_address_t * eh_addr, u16 eh_port, u8 proto, u32 fib_index,
+               u32 total_pkts, u64 total_bytes, u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_session_key_t key;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_session_t *s;
+  snat_main_per_thread_data_t *tsm;
+
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+
+  key.addr.as_u32 = out_addr->as_u32;
+  key.port = out_port;
+  key.protocol = proto;
+  key.fib_index = fib_index;
+  kv.key = key.as_u64;
+  if (clib_bihash_search_8_8 (&tsm->out2in, &kv, &value))
+    return;
+
+  s = pool_elt_at_index (tsm->sessions, value.value);
+  s->total_pkts = total_pkts;
+  s->total_bytes = total_bytes;
+}
+
+void
+nat_ha_sadd_ed_cb (ip4_address_t * in_addr, u16 in_port,
+                  ip4_address_t * out_addr, u16 out_port,
+                  ip4_address_t * eh_addr, u16 eh_port,
+                  ip4_address_t * ehn_addr, u16 ehn_port, u8 proto,
+                  u32 fib_index, u16 flags, u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_session_key_t key;
+  snat_user_t *u;
+  snat_session_t *s;
+  clib_bihash_kv_16_8_t kv;
+  f64 now = vlib_time_now (sm->vlib_main);
+  nat_outside_fib_t *outside_fib;
+  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
+  snat_main_per_thread_data_t *tsm;
+  fib_prefix_t pfx = {
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_len = 32,
+    .fp_addr = {
+               .ip4.as_u32 = eh_addr->as_u32,
+               },
+  };
+
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+
+  key.addr.as_u32 = out_addr->as_u32;
+  key.port = out_port;
+  key.protocol = proto;
+
+  if (!(flags & SNAT_SESSION_FLAG_STATIC_MAPPING))
+    {
+      if (nat_set_outside_address_and_port
+         (sm->addresses, thread_index, &key))
+       return;
+    }
+
+  key.addr.as_u32 = ehn_addr->as_u32;
+  key.port = ehn_port;
+  if (flags & SNAT_SESSION_FLAG_TWICE_NAT)
+    {
+      if (nat_set_outside_address_and_port
+         (sm->twice_nat_addresses, thread_index, &key))
+       return;
+    }
+
+  u = nat_user_get_or_create (sm, in_addr, fib_index, thread_index);
+  if (!u)
+    return;
+
+  s = nat_ed_session_alloc (sm, u, thread_index, now);
+  if (!s)
+    return;
+
+  s->last_heard = now;
+  s->flags = flags;
+  s->ext_host_nat_addr.as_u32 = s->ext_host_addr.as_u32 = eh_addr->as_u32;
+  s->ext_host_nat_port = s->ext_host_port = eh_port;
+  if (is_twice_nat_session (s))
+    {
+      s->ext_host_nat_addr.as_u32 = ehn_addr->as_u32;
+      s->ext_host_nat_port = ehn_port;
+    }
+  user_session_increment (sm, u, snat_is_session_static (s));
+  switch (vec_len (sm->outside_fibs))
+    {
+    case 0:
+      key.fib_index = sm->outside_fib_index;
+      break;
+    case 1:
+      key.fib_index = sm->outside_fibs[0].fib_index;
+      break;
+    default:
+      /* *INDENT-OFF* */
+      vec_foreach (outside_fib, sm->outside_fibs)
+        {
+          fei = fib_table_lookup (outside_fib->fib_index, &pfx);
+          if (FIB_NODE_INDEX_INVALID != fei)
+            {
+              if (fib_entry_get_resolving_interface (fei) != ~0)
+                {
+                  key.fib_index = outside_fib->fib_index;
+                  break;
+                }
+            }
+        }
+      /* *INDENT-ON* */
+      break;
+    }
+  key.addr.as_u32 = out_addr->as_u32;
+  key.port = out_port;
+  s->out2in = key;
+  kv.value = s - tsm->sessions;
+
+  key.addr.as_u32 = in_addr->as_u32;
+  key.port = in_port;
+  key.fib_index = fib_index;
+  s->in2out = key;
+
+  make_ed_kv (&kv, in_addr, &s->ext_host_nat_addr,
+             snat_proto_to_ip_proto (proto), fib_index, in_port,
+             s->ext_host_nat_port);
+  if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &kv, 1))
+    nat_log_warn ("in2out key add failed");
+
+  make_ed_kv (&kv, out_addr, eh_addr, snat_proto_to_ip_proto (proto),
+             s->out2in.fib_index, out_port, eh_port);
+  if (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &kv, 1))
+    nat_log_warn ("out2in key add failed");
+}
+
+void
+nat_ha_sdel_ed_cb (ip4_address_t * out_addr, u16 out_port,
+                  ip4_address_t * eh_addr, u16 eh_port, u8 proto,
+                  u32 fib_index, u32 ti)
+{
+  snat_main_t *sm = &snat_main;
+  nat_ed_ses_key_t key;
+  clib_bihash_kv_16_8_t kv, value;
+  u32 thread_index;
+  snat_session_t *s;
+  snat_main_per_thread_data_t *tsm;
+
+  if (sm->num_workers > 1)
+    thread_index =
+      sm->first_worker_index +
+      (sm->workers[(clib_net_to_host_u16 (out_port) -
+                   1024) / sm->port_per_thread]);
+  else
+    thread_index = sm->num_workers;
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+
+  key.l_addr.as_u32 = out_addr->as_u32;
+  key.l_port = out_port;
+  key.r_addr.as_u32 = eh_addr->as_u32;
+  key.r_port = eh_port;
+  key.proto = proto;
+  key.fib_index = fib_index;
+  kv.key[0] = key.as_u64[0];
+  kv.key[1] = key.as_u64[1];
+  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv, &value))
+    return;
+
+  s = pool_elt_at_index (tsm->sessions, value.value);
+  nat_free_session_data (sm, s, thread_index, 1);
+  nat44_delete_session (sm, s, thread_index);
+}
+
+void
+nat_ha_sref_ed_cb (ip4_address_t * out_addr, u16 out_port,
+                  ip4_address_t * eh_addr, u16 eh_port, u8 proto,
+                  u32 fib_index, u32 total_pkts, u64 total_bytes,
+                  u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  nat_ed_ses_key_t key;
+  clib_bihash_kv_16_8_t kv, value;
+  snat_session_t *s;
+  snat_main_per_thread_data_t *tsm;
+
+  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+
+  key.l_addr.as_u32 = out_addr->as_u32;
+  key.l_port = out_port;
+  key.r_addr.as_u32 = eh_addr->as_u32;
+  key.r_port = eh_port;
+  key.proto = proto;
+  key.fib_index = fib_index;
+  kv.key[0] = key.as_u64[0];
+  kv.key[1] = key.as_u64[1];
+  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv, &value))
+    return;
+
+  s = pool_elt_at_index (tsm->sessions, value.value);
+  s->total_pkts = total_pkts;
+  s->total_bytes = total_bytes;
+}
+
 static clib_error_t *
 snat_config (vlib_main_t * vm, unformat_input_t * input)
 {
@@ -3065,6 +3624,8 @@ snat_config (vlib_main_t * vm, unformat_input_t * input)
          sm->icmp_match_in2out_cb = icmp_match_in2out_ed;
          sm->icmp_match_out2in_cb = icmp_match_out2in_ed;
          nat_affinity_init (vm);
+         nat_ha_init (vm, nat_ha_sadd_ed_cb, nat_ha_sdel_ed_cb,
+                      nat_ha_sref_ed_cb);
        }
       else
        {
@@ -3075,6 +3636,7 @@ snat_config (vlib_main_t * vm, unformat_input_t * input)
          sm->out2in_node_index = snat_out2in_node.index;
          sm->icmp_match_in2out_cb = icmp_match_in2out_slow;
          sm->icmp_match_out2in_cb = icmp_match_out2in_slow;
+         nat_ha_init (vm, nat_ha_sadd_cb, nat_ha_sdel_cb, nat_ha_sref_cb);
        }
       if (!static_mapping_only ||
          (static_mapping_only && static_mapping_connection_tracking))
@@ -3395,7 +3957,7 @@ nat44_del_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
        return VNET_API_ERROR_UNSPECIFIED;
 
       s = pool_elt_at_index (tsm->sessions, value.value);
-      nat_free_session_data (sm, s, tsm - sm->per_thread_data);
+      nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
       nat44_delete_session (sm, s, tsm - sm->per_thread_data);
       return 0;
     }
@@ -3442,7 +4004,7 @@ nat44_del_ed_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
   if (pool_is_free_index (tsm->sessions, value.value))
     return VNET_API_ERROR_UNSPECIFIED;
   s = pool_elt_at_index (tsm->sessions, value.value);
-  nat_free_session_data (sm, s, tsm - sm->per_thread_data);
+  nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
   nat44_delete_session (sm, s, tsm - sm->per_thread_data);
   return 0;
 }