nat: Final NAT44 EI/ED split patch

This patch achieves complete separation of
endpoint-dependent and endpoint-independent IPv4 NAT
features. Some common stuff is also moved to NAT
library.

Type: refactor

Change-Id: I52468b7e2b5ac28958a2baf8e2ea01787322e801
Signed-off-by: Filip Varga <fivarga@cisco.com>

1 files changed, 3610 insertions, 0 deletions

diff --git a/src/plugins/nat/nat44-ed/nat44_ed.c b/src/plugins/nat/nat44-ed/nat44_ed.c
new file mode 100644
index 00000000000..d9d35fc55bc
--- /dev/null
+++ b/src/plugins/nat/nat44-ed/nat44_ed.c
@@ -0,0 +1,3610 @@
+/*
+ * snat.c - simple nat plugin
+ *
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vpp/app/version.h>
+
+#include <vnet/vnet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/ip/ip4.h>
+#include <vnet/ip/ip_table.h>
+#include <vnet/ip/reass/ip4_sv_reass.h>
+#include <vnet/fib/fib_table.h>
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/plugin/plugin.h>
+#include <vppinfra/bihash_16_8.h>
+
+#include <nat/lib/log.h>
+#include <nat/lib/nat_syslog.h>
+#include <nat/lib/nat_inlines.h>
+#include <nat/lib/ipfix_logging.h>
+
+#include <nat/nat44-ed/nat44_ed.h>
+#include <nat/nat44-ed/nat44_ed_affinity.h>
+#include <nat/nat44-ed/nat44_ed_inlines.h>
+
+snat_main_t snat_main;
+
+static_always_inline void nat_validate_interface_counters (snat_main_t *sm,
+							   u32 sw_if_index);
+
+#define skip_if_disabled()                                                    \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (!sm->enabled))                                       \
+	return;                                                               \
+    }                                                                         \
+  while (0)
+
+#define fail_if_enabled()                                                     \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (sm->enabled))                                        \
+	{                                                                     \
+	  nat_log_err ("plugin enabled");                                     \
+	  return 1;                                                           \
+	}                                                                     \
+    }                                                                         \
+  while (0)
+
+#define fail_if_disabled()                                                    \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (!sm->enabled))                                       \
+	{                                                                     \
+	  nat_log_err ("plugin disabled");                                    \
+	  return 1;                                                           \
+	}                                                                     \
+    }                                                                         \
+  while (0)
+
+/* *INDENT-OFF* */
+/* Hook up input features */
+VNET_FEATURE_INIT (nat_pre_in2out, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat-pre-in2out",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa",
+			       "ip4-sv-reassembly-feature"),
+};
+VNET_FEATURE_INIT (nat_pre_out2in, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat-pre-out2in",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa",
+                               "ip4-dhcp-client-detect",
+			       "ip4-sv-reassembly-feature"),
+};
+VNET_FEATURE_INIT (snat_in2out_worker_handoff, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-in2out-worker-handoff",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa"),
+};
+VNET_FEATURE_INIT (snat_out2in_worker_handoff, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-out2in-worker-handoff",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa",
+                               "ip4-dhcp-client-detect"),
+};
+VNET_FEATURE_INIT (ip4_snat_in2out, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-in2out",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
+};
+VNET_FEATURE_INIT (ip4_snat_out2in, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-out2in",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature",
+                               "ip4-dhcp-client-detect"),
+};
+VNET_FEATURE_INIT (ip4_nat44_ed_in2out, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-ed-in2out",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
+};
+VNET_FEATURE_INIT (ip4_nat44_ed_out2in, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-ed-out2in",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature",
+                               "ip4-dhcp-client-detect"),
+};
+VNET_FEATURE_INIT (ip4_nat44_ed_classify, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-ed-classify",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
+};
+VNET_FEATURE_INIT (ip4_nat_handoff_classify, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-handoff-classify",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
+};
+VNET_FEATURE_INIT (ip4_snat_in2out_fast, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-in2out-fast",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
+};
+VNET_FEATURE_INIT (ip4_snat_out2in_fast, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "nat44-out2in-fast",
+  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature",
+                               "ip4-dhcp-client-detect"),
+};
+
+/* Hook up output features */
+VNET_FEATURE_INIT (ip4_snat_in2out_output, static) = {
+  .arc_name = "ip4-output",
+  .node_name = "nat44-in2out-output",
+  .runs_after = VNET_FEATURES ("acl-plugin-out-ip4-fa","ip4-sv-reassembly-output-feature"),
+};
+VNET_FEATURE_INIT (ip4_snat_in2out_output_worker_handoff, static) = {
+  .arc_name = "ip4-output",
+  .node_name = "nat44-in2out-output-worker-handoff",
+  .runs_after = VNET_FEATURES ("acl-plugin-out-ip4-fa","ip4-sv-reassembly-output-feature"),
+};
+VNET_FEATURE_INIT (nat_pre_in2out_output, static) = {
+  .arc_name = "ip4-output",
+  .node_name = "nat-pre-in2out-output",
+  .runs_after = VNET_FEATURES ("ip4-sv-reassembly-output-feature"),
+  .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
+};
+VNET_FEATURE_INIT (ip4_nat44_ed_in2out_output, static) = {
+  .arc_name = "ip4-output",
+  .node_name = "nat44-ed-in2out-output",
+  .runs_after = VNET_FEATURES ("ip4-sv-reassembly-output-feature"),
+  .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
+};
+
+VLIB_PLUGIN_REGISTER () = {
+    .version = VPP_BUILD_VER,
+    .description = "Network Address Translation (NAT)",
+};
+/* *INDENT-ON* */
+
+static void nat44_ed_db_init (u32 translations, u32 translation_buckets);
+
+static void nat44_ed_db_free ();
+
+static u32
+nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
+			       u32 rx_fib_index, u8 is_output);
+
+static u32
+nat44_ed_get_worker_in2out_cb (ip4_header_t * ip, u32 rx_fib_index,
+			       u8 is_output);
+
+u32 nat_calc_bihash_buckets (u32 n_elts);
+
+u8 *
+format_session_kvp (u8 * s, va_list * args)
+{
+  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
+
+  s = format (s, "%U thread-index %llu session-index %llu", format_snat_key,
+	      v->key, nat_value_get_thread_index (v),
+	      nat_value_get_session_index (v));
+
+  return s;
+}
+
+u8 *
+format_static_mapping_kvp (u8 * s, va_list * args)
+{
+  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
+
+  s = format (s, "%U static-mapping-index %llu",
+	      format_snat_key, v->key, v->value);
+
+  return s;
+}
+
+u8 *
+format_ed_session_kvp (u8 * s, va_list * args)
+{
+  clib_bihash_kv_16_8_t *v = va_arg (*args, clib_bihash_kv_16_8_t *);
+
+  u8 proto;
+  u16 r_port, l_port;
+  ip4_address_t l_addr, r_addr;
+  u32 fib_index;
+
+  split_ed_kv (v, &l_addr, &r_addr, &proto, &fib_index, &l_port, &r_port);
+  s = format (s,
+	      "local %U:%d remote %U:%d proto %U fib %d thread-index %u "
+	      "session-index %u",
+	      format_ip4_address, &l_addr, clib_net_to_host_u16 (l_port),
+	      format_ip4_address, &r_addr, clib_net_to_host_u16 (r_port),
+	      format_ip_protocol, proto, fib_index,
+	      ed_value_get_thread_index (v), ed_value_get_session_index (v));
+
+  return s;
+}
+
+void
+nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index,
+		       u8 is_ha)
+{
+      per_vrf_sessions_unregister_session (s, thread_index);
+
+      if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 0))
+	nat_elog_warn (sm, "flow hash del failed");
+
+      if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 0))
+	nat_elog_warn (sm, "flow hash del failed");
+
+  if (is_fwd_bypass_session (s))
+    {
+      return;
+    }
+
+      if (is_affinity_sessions (s))
+	nat_affinity_unlock (s->ext_host_addr, s->out2in.addr,
+			     s->nat_proto, s->out2in.port);
+
+      if (!is_ha)
+	nat_syslog_nat44_sdel (
+	  0, 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->nat_proto,
+	  is_twice_nat_session (s));
+
+  if (snat_is_unk_proto_session (s))
+    return;
+
+  if (!is_ha)
+    {
+      /* log NAT event */
+      nat_ipfix_logging_nat44_ses_delete (thread_index,
+					  s->in2out.addr.as_u32,
+					  s->out2in.addr.as_u32,
+					  s->nat_proto,
+					  s->in2out.port,
+					  s->out2in.port,
+					  s->in2out.fib_index);
+    }
+
+  /* Twice NAT address and port for external host */
+  if (is_twice_nat_session (s))
+    {
+      snat_free_outside_address_and_port (sm->twice_nat_addresses,
+					  thread_index,
+					  &s->ext_host_nat_addr,
+					  s->ext_host_nat_port, s->nat_proto);
+    }
+
+  if (snat_is_session_static (s))
+    return;
+
+  snat_free_outside_address_and_port (sm->addresses, thread_index,
+				      &s->out2in.addr, s->out2in.port,
+				      s->nat_proto);
+}
+
+void
+snat_add_del_addr_to_fib (ip4_address_t * addr, u8 p_len, u32 sw_if_index,
+			  int is_add)
+{
+  snat_main_t *sm = &snat_main;
+  fib_prefix_t prefix = {
+    .fp_len = p_len,
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_addr = {
+		.ip4.as_u32 = addr->as_u32,
+		},
+  };
+  u32 fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);
+
+  if (is_add)
+    fib_table_entry_update_one_path (fib_index,
+				     &prefix,
+				     sm->fib_src_low,
+				     (FIB_ENTRY_FLAG_CONNECTED |
+				      FIB_ENTRY_FLAG_LOCAL |
+				      FIB_ENTRY_FLAG_EXCLUSIVE),
+				     DPO_PROTO_IP4,
+				     NULL,
+				     sw_if_index,
+				     ~0, 1, NULL, FIB_ROUTE_PATH_FLAG_NONE);
+  else
+    fib_table_entry_delete (fib_index, &prefix, sm->fib_src_low);
+}
+
+int
+snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
+		  u8 twice_nat)
+{
+  snat_address_t *ap;
+  snat_interface_t *i;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+
+  /* Check if address already exists */
+  /* *INDENT-OFF* */
+  vec_foreach (ap, twice_nat ? sm->twice_nat_addresses : sm->addresses)
+    {
+      if (ap->addr.as_u32 == addr->as_u32)
+        {
+          nat_log_err ("address exist");
+          return VNET_API_ERROR_VALUE_EXIST;
+        }
+    }
+  /* *INDENT-ON* */
+
+  if (twice_nat)
+    vec_add2 (sm->twice_nat_addresses, ap, 1);
+  else
+    vec_add2 (sm->addresses, ap, 1);
+
+  ap->addr = *addr;
+  if (vrf_id != ~0)
+    ap->fib_index =
+      fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
+					 sm->fib_src_low);
+  else
+    ap->fib_index = ~0;
+
+  /* *INDENT-OFF* */
+  #define _(N, i, n, s) \
+    clib_memset(ap->busy_##n##_port_refcounts, 0, sizeof(ap->busy_##n##_port_refcounts));\
+    ap->busy_##n##_ports = 0; \
+    ap->busy_##n##_ports_per_thread = 0;\
+    vec_validate_init_empty (ap->busy_##n##_ports_per_thread, tm->n_vlib_mains - 1, 0);
+    foreach_nat_protocol
+  #undef _
+  /* *INDENT-ON* */
+
+  if (twice_nat)
+    return 0;
+
+  /* Add external address to FIB */
+  /* *INDENT-OFF* */
+  pool_foreach (i, sm->interfaces)
+   {
+     if (nat_interface_is_inside (i))
+       continue;
+
+     snat_add_del_addr_to_fib (addr, 32, i->sw_if_index, 1);
+     break;
+  }
+  pool_foreach (i, sm->output_feature_interfaces)
+   {
+     if (nat_interface_is_inside (i))
+       continue;
+
+     snat_add_del_addr_to_fib (addr, 32, i->sw_if_index, 1);
+     break;
+  }
+  /* *INDENT-ON* */
+
+  return 0;
+}
+
+static int
+is_snat_address_used_in_static_mapping (snat_main_t * sm, ip4_address_t addr)
+{
+  snat_static_mapping_t *m;
+  /* *INDENT-OFF* */
+  pool_foreach (m, sm->static_mappings)
+   {
+      if (is_addr_only_static_mapping (m) ||
+          is_out2in_only_static_mapping (m) ||
+          is_identity_static_mapping (m))
+        continue;
+      if (m->external_addr.as_u32 == addr.as_u32)
+        return 1;
+  }
+  /* *INDENT-ON* */
+
+  return 0;
+}
+
+static void
+snat_add_static_mapping_when_resolved (snat_main_t *sm, ip4_address_t l_addr,
+				       u16 l_port, u32 sw_if_index, u16 e_port,
+				       u32 vrf_id, nat_protocol_t proto,
+				       int addr_only, u8 *tag, int twice_nat,
+				       int out2in_only, int identity_nat,
+				       ip4_address_t pool_addr, int exact)
+{
+  snat_static_map_resolve_t *rp;
+
+  vec_add2 (sm->to_resolve, rp, 1);
+  rp->l_addr.as_u32 = l_addr.as_u32;
+  rp->l_port = l_port;
+  rp->sw_if_index = sw_if_index;
+  rp->e_port = e_port;
+  rp->vrf_id = vrf_id;
+  rp->proto = proto;
+  rp->addr_only = addr_only;
+  rp->twice_nat = twice_nat;
+  rp->out2in_only = out2in_only;
+  rp->identity_nat = identity_nat;
+  rp->tag = vec_dup (tag);
+  rp->pool_addr = pool_addr;
+  rp->exact = exact;
+}
+
+u32
+get_thread_idx_by_port (u16 e_port)
+{
+  snat_main_t *sm = &snat_main;
+  u32 thread_idx = sm->num_workers;
+  if (sm->num_workers > 1)
+    {
+      thread_idx =
+	sm->first_worker_index +
+	sm->workers[(e_port - 1024) / sm->port_per_thread];
+    }
+  return thread_idx;
+}
+
+void
+nat_ed_static_mapping_del_sessions (snat_main_t * sm,
+				    snat_main_per_thread_data_t * tsm,
+				    ip4_address_t l_addr,
+				    u16 l_port,
+				    u8 protocol,
+				    u32 fib_index, int addr_only,
+				    ip4_address_t e_addr, u16 e_port)
+{
+  snat_session_t *s;
+  u32 *indexes_to_free = NULL;
+  /* *INDENT-OFF* */
+  pool_foreach (s, tsm->sessions) {
+    if (s->in2out.fib_index != fib_index ||
+        s->in2out.addr.as_u32 != l_addr.as_u32)
+      {
+        continue;
+      }
+    if (!addr_only)
+      {
+        if ((s->out2in.addr.as_u32 != e_addr.as_u32) ||
+            s->out2in.port != e_port ||
+            s->in2out.port != l_port ||
+            s->nat_proto != protocol)
+          continue;
+      }
+
+    if (is_lb_session (s))
+      continue;
+    if (!snat_is_session_static (s))
+      continue;
+    nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
+    vec_add1 (indexes_to_free, s - tsm->sessions);
+    if (!addr_only)
+      break;
+  }
+  /* *INDENT-ON* */
+  u32 *ses_index;
+  vec_foreach (ses_index, indexes_to_free)
+  {
+    s = pool_elt_at_index (tsm->sessions, *ses_index);
+    nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+  }
+  vec_free (indexes_to_free);
+}
+
+int
+snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+			 u16 l_port, u16 e_port, u32 vrf_id, int addr_only,
+			 u32 sw_if_index, nat_protocol_t proto, int is_add,
+			 twice_nat_type_t twice_nat, u8 out2in_only, u8 *tag,
+			 u8 identity_nat, ip4_address_t pool_addr, int exact)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_mapping_t *m;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_address_t *a = 0;
+  u32 fib_index = ~0;
+  snat_interface_t *interface;
+  snat_main_per_thread_data_t *tsm;
+  snat_static_map_resolve_t *rp, *rp_match = 0;
+  nat44_lb_addr_port_t *local;
+  u32 find = ~0;
+  int i;
+
+  /* If the external address is a specific interface address */
+  if (sw_if_index != ~0)
+    {
+      ip4_address_t *first_int_addr;
+
+      for (i = 0; i < vec_len (sm->to_resolve); i++)
+	{
+	  rp = sm->to_resolve + i;
+	  if (rp->sw_if_index != sw_if_index ||
+	      rp->l_addr.as_u32 != l_addr.as_u32 ||
+	      rp->vrf_id != vrf_id || rp->addr_only != addr_only)
+	    continue;
+
+	  if (!addr_only)
+	    {
+	      if ((rp->l_port != l_port && rp->e_port != e_port)
+		  || rp->proto != proto)
+		continue;
+	    }
+
+	  rp_match = rp;
+	  break;
+	}
+
+      /* Might be already set... */
+      first_int_addr = ip4_interface_first_address
+	(sm->ip4_main, sw_if_index, 0 /* just want the address */ );
+
+      if (is_add)
+	{
+	  if (rp_match)
+	    return VNET_API_ERROR_VALUE_EXIST;
+
+	  snat_add_static_mapping_when_resolved (
+	    sm, l_addr, l_port, sw_if_index, e_port, vrf_id, proto, addr_only,
+	    tag, twice_nat, out2in_only, identity_nat, pool_addr, exact);
+
+	  /* DHCP resolution required? */
+	  if (first_int_addr == 0)
+	    {
+	      return 0;
+	    }
+	  else
+	    {
+	      e_addr.as_u32 = first_int_addr->as_u32;
+	      /* Identity mapping? */
+	      if (l_addr.as_u32 == 0)
+		l_addr.as_u32 = e_addr.as_u32;
+	    }
+	}
+      else
+	{
+	  if (!rp_match)
+	    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+	  vec_del1 (sm->to_resolve, i);
+
+	  if (first_int_addr)
+	    {
+	      e_addr.as_u32 = first_int_addr->as_u32;
+	      /* Identity mapping? */
+	      if (l_addr.as_u32 == 0)
+		l_addr.as_u32 = e_addr.as_u32;
+	    }
+	  else
+	    return 0;
+	}
+    }
+
+  init_nat_k (&kv, e_addr, addr_only ? 0 : e_port, 0, addr_only ? 0 : proto);
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    m = 0;
+  else
+    m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (is_add)
+    {
+      if (m)
+	{
+	  if (is_identity_static_mapping (m))
+	    {
+              /* *INDENT-OFF* */
+              pool_foreach (local, m->locals)
+               {
+                if (local->vrf_id == vrf_id)
+                  return VNET_API_ERROR_VALUE_EXIST;
+              }
+              /* *INDENT-ON* */
+	      pool_get (m->locals, local);
+	      local->vrf_id = vrf_id;
+	      local->fib_index =
+		fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
+						   sm->fib_src_low);
+	      init_nat_kv (&kv, m->local_addr, m->local_port, local->fib_index,
+			   m->proto, 0, m - sm->static_mappings);
+	      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+	      return 0;
+	    }
+	  else
+	    return VNET_API_ERROR_VALUE_EXIST;
+	}
+
+      if (twice_nat && addr_only)
+	return VNET_API_ERROR_UNSUPPORTED;
+
+      /* Convert VRF id to FIB index */
+      if (vrf_id != ~0)
+	fib_index =
+	  fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
+					     sm->fib_src_low);
+      /* If not specified use inside VRF id from SNAT plugin startup config */
+      else
+	{
+	  fib_index = sm->inside_fib_index;
+	  vrf_id = sm->inside_vrf_id;
+	  fib_table_lock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+	}
+
+      if (!(out2in_only || identity_nat))
+	{
+	  init_nat_k (&kv, l_addr, addr_only ? 0 : l_port, fib_index,
+		      addr_only ? 0 : proto);
+	  if (!clib_bihash_search_8_8
+	      (&sm->static_mapping_by_local, &kv, &value))
+	    return VNET_API_ERROR_VALUE_EXIST;
+	}
+
+      /* Find external address in allocated addresses and reserve port for
+         address and port pair mapping when dynamic translations enabled */
+      if (!(addr_only || sm->static_mapping_only || out2in_only))
+	{
+	  for (i = 0; i < vec_len (sm->addresses); i++)
+	    {
+	      if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+		{
+		  a = sm->addresses + i;
+		  /* External port must be unused */
+		  switch (proto)
+		    {
+#define _(N, j, n, s) \
+                    case NAT_PROTOCOL_##N: \
+                      if (a->busy_##n##_port_refcounts[e_port]) \
+                        return VNET_API_ERROR_INVALID_VALUE; \
+                      ++a->busy_##n##_port_refcounts[e_port]; \
+                      if (e_port > 1024) \
+                        { \
+                          a->busy_##n##_ports++; \
+                          a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]++; \
+                        } \
+                      break;
+		      foreach_nat_protocol
+#undef _
+			default : nat_elog_info (sm, "unknown protocol");
+		      return VNET_API_ERROR_INVALID_VALUE_2;
+		    }
+		  break;
+		}
+	    }
+	  /* External address must be allocated */
+	  if (!a && (l_addr.as_u32 != e_addr.as_u32))
+	    {
+	      if (sw_if_index != ~0)
+		{
+		  for (i = 0; i < vec_len (sm->to_resolve); i++)
+		    {
+		      rp = sm->to_resolve + i;
+		      if (rp->addr_only)
+			continue;
+		      if (rp->sw_if_index != sw_if_index &&
+			  rp->l_addr.as_u32 != l_addr.as_u32 &&
+			  rp->vrf_id != vrf_id && rp->l_port != l_port &&
+			  rp->e_port != e_port && rp->proto != proto)
+			continue;
+
+		      vec_del1 (sm->to_resolve, i);
+		      break;
+		    }
+		}
+	      return VNET_API_ERROR_NO_SUCH_ENTRY;
+	    }
+	}
+
+      pool_get (sm->static_mappings, m);
+      clib_memset (m, 0, sizeof (*m));
+      m->tag = vec_dup (tag);
+      m->local_addr = l_addr;
+      m->external_addr = e_addr;
+      m->twice_nat = twice_nat;
+
+      if (twice_nat == TWICE_NAT && exact)
+	{
+	  m->flags |= NAT_STATIC_MAPPING_FLAG_EXACT_ADDRESS;
+	  m->pool_addr = pool_addr;
+	}
+
+      if (out2in_only)
+	m->flags |= NAT_STATIC_MAPPING_FLAG_OUT2IN_ONLY;
+      if (addr_only)
+	m->flags |= NAT_STATIC_MAPPING_FLAG_ADDR_ONLY;
+      if (identity_nat)
+	{
+	  m->flags |= NAT_STATIC_MAPPING_FLAG_IDENTITY_NAT;
+	  pool_get (m->locals, local);
+	  local->vrf_id = vrf_id;
+	  local->fib_index = fib_index;
+	}
+      else
+	{
+	  m->vrf_id = vrf_id;
+	  m->fib_index = fib_index;
+	}
+      if (!addr_only)
+	{
+	  m->local_port = l_port;
+	  m->external_port = e_port;
+	  m->proto = proto;
+	}
+
+      if (sm->num_workers > 1)
+	{
+	  ip4_header_t ip = {
+	    .src_address = m->local_addr,
+	  };
+	  vec_add1 (m->workers, sm->worker_in2out_cb (&ip, m->fib_index, 0));
+	  tsm = vec_elt_at_index (sm->per_thread_data, m->workers[0]);
+	}
+      else
+	tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+      if (!out2in_only)
+	{
+	  init_nat_kv (&kv, m->local_addr, m->local_port, fib_index, m->proto,
+		       0, m - sm->static_mappings);
+	  clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+	}
+
+      init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto, 0,
+		   m - sm->static_mappings);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1);
+    }
+  else
+    {
+      if (!m)
+	{
+	  if (sw_if_index != ~0)
+	    return 0;
+	  else
+	    return VNET_API_ERROR_NO_SUCH_ENTRY;
+	}
+
+      if (identity_nat)
+	{
+	  if (vrf_id == ~0)
+	    vrf_id = sm->inside_vrf_id;
+
+          /* *INDENT-OFF* */
+          pool_foreach (local, m->locals)
+           {
+	    if (local->vrf_id == vrf_id)
+              find = local - m->locals;
+	  }
+          /* *INDENT-ON* */
+	  if (find == ~0)
+	    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+	  local = pool_elt_at_index (m->locals, find);
+	  fib_index = local->fib_index;
+	  pool_put (m->locals, local);
+	}
+      else
+	fib_index = m->fib_index;
+
+      /* Free external address port */
+      if (!(addr_only || sm->static_mapping_only || out2in_only))
+	{
+	  for (i = 0; i < vec_len (sm->addresses); i++)
+	    {
+	      if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+		{
+		  a = sm->addresses + i;
+		  switch (proto)
+		    {
+#define _(N, j, n, s) \
+                    case NAT_PROTOCOL_##N: \
+                      --a->busy_##n##_port_refcounts[e_port]; \
+                      if (e_port > 1024) \
+                        { \
+                          a->busy_##n##_ports--; \
+                          a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]--; \
+                        } \
+                      break;
+		      foreach_nat_protocol
+#undef _
+			default : nat_elog_info (sm, "unknown protocol");
+		      return VNET_API_ERROR_INVALID_VALUE_2;
+		    }
+		  break;
+		}
+	    }
+	}
+
+      if (sm->num_workers > 1)
+	tsm = vec_elt_at_index (sm->per_thread_data, m->workers[0]);
+      else
+	tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+      init_nat_k (&kv, m->local_addr, m->local_port, fib_index, m->proto);
+      if (!out2in_only)
+	clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0);
+
+      /* Delete session(s) for static mapping if exist */
+      if (!(sm->static_mapping_only) ||
+	  (sm->static_mapping_only && sm->static_mapping_connection_tracking))
+	{
+	  nat_ed_static_mapping_del_sessions (
+	    sm, tsm, m->local_addr, m->local_port, m->proto, fib_index,
+	    addr_only, e_addr, e_port);
+	}
+
+      fib_table_unlock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+      if (pool_elts (m->locals))
+	return 0;
+
+      init_nat_k (&kv, m->external_addr, m->external_port, 0, m->proto);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0);
+
+      vec_free (m->tag);
+      vec_free (m->workers);
+      /* Delete static mapping from pool */
+      pool_put (sm->static_mappings, m);
+    }
+
+  if (!addr_only || (l_addr.as_u32 == e_addr.as_u32))
+    return 0;
+
+  /* Add/delete external address to FIB */
+  /* *INDENT-OFF* */
+  pool_foreach (interface, sm->interfaces)
+   {
+     if (nat_interface_is_inside (interface))
+       continue;
+
+     snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, is_add);
+     break;
+  }
+  pool_foreach (interface, sm->output_feature_interfaces)
+   {
+     if (nat_interface_is_inside (interface))
+       continue;
+
+     snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, is_add);
+     break;
+  }
+  /* *INDENT-ON* */
+
+  return 0;
+}
+
+int
+nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
+				 nat_protocol_t proto,
+				 nat44_lb_addr_port_t * locals, u8 is_add,
+				 twice_nat_type_t twice_nat, u8 out2in_only,
+				 u8 * tag, u32 affinity)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_mapping_t *m;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_address_t *a = 0;
+  int i;
+  nat44_lb_addr_port_t *local;
+  snat_main_per_thread_data_t *tsm;
+  snat_session_t *s;
+  uword *bitmap = 0;
+
+  init_nat_k (&kv, e_addr, e_port, 0, proto);
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    m = 0;
+  else
+    m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (is_add)
+    {
+      if (m)
+	return VNET_API_ERROR_VALUE_EXIST;
+
+      if (vec_len (locals) < 2)
+	return VNET_API_ERROR_INVALID_VALUE;
+
+      /* Find external address in allocated addresses and reserve port for
+         address and port pair mapping when dynamic translations enabled */
+      if (!(sm->static_mapping_only || out2in_only))
+	{
+	  for (i = 0; i < vec_len (sm->addresses); i++)
+	    {
+	      if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+		{
+		  a = sm->addresses + i;
+		  /* External port must be unused */
+		  switch (proto)
+		    {
+#define _(N, j, n, s) \
+                    case NAT_PROTOCOL_##N: \
+                      if (a->busy_##n##_port_refcounts[e_port]) \
+                        return VNET_API_ERROR_INVALID_VALUE; \
+                      ++a->busy_##n##_port_refcounts[e_port]; \
+                      if (e_port > 1024) \
+                        { \
+                          a->busy_##n##_ports++; \
+                          a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]++; \
+                        } \
+                      break;
+		      foreach_nat_protocol
+#undef _
+			default : nat_elog_info (sm, "unknown protocol");
+		      return VNET_API_ERROR_INVALID_VALUE_2;
+		    }
+		  break;
+		}
+	    }
+	  /* External address must be allocated */
+	  if (!a)
+	    return VNET_API_ERROR_NO_SUCH_ENTRY;
+	}
+
+      pool_get (sm->static_mappings, m);
+      clib_memset (m, 0, sizeof (*m));
+      m->tag = vec_dup (tag);
+      m->external_addr = e_addr;
+      m->external_port = e_port;
+      m->proto = proto;
+      m->twice_nat = twice_nat;
+      m->flags |= NAT_STATIC_MAPPING_FLAG_LB;
+      if (out2in_only)
+	m->flags |= NAT_STATIC_MAPPING_FLAG_OUT2IN_ONLY;
+      m->affinity = affinity;
+
+      if (affinity)
+	m->affinity_per_service_list_head_index =
+	  nat_affinity_get_per_service_list_head_index ();
+      else
+	m->affinity_per_service_list_head_index = ~0;
+
+      init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto, 0,
+		   m - sm->static_mappings);
+      if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1))
+	{
+	  nat_elog_err (sm, "static_mapping_by_external key add failed");
+	  return VNET_API_ERROR_UNSPECIFIED;
+	}
+
+      for (i = 0; i < vec_len (locals); i++)
+	{
+	  locals[i].fib_index =
+	    fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4,
+					       locals[i].vrf_id,
+					       sm->fib_src_low);
+	  if (!out2in_only)
+	    {
+	      init_nat_kv (&kv, locals[i].addr, locals[i].port,
+			   locals[i].fib_index, m->proto, 0,
+			   m - sm->static_mappings);
+	      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+	    }
+	  locals[i].prefix = (i == 0) ? locals[i].probability :
+	    (locals[i - 1].prefix + locals[i].probability);
+	  pool_get (m->locals, local);
+	  *local = locals[i];
+	  if (sm->num_workers > 1)
+	    {
+	      ip4_header_t ip = {
+		.src_address = locals[i].addr,
+	      };
+	      bitmap =
+		clib_bitmap_set (bitmap,
+				 sm->worker_in2out_cb (&ip, m->fib_index, 0),
+				 1);
+	    }
+	}
+
+      /* Assign workers */
+      if (sm->num_workers > 1)
+	{
+          /* *INDENT-OFF* */
+          clib_bitmap_foreach (i, bitmap)
+             {
+               vec_add1(m->workers, i);
+            }
+          /* *INDENT-ON* */
+	}
+    }
+  else
+    {
+      if (!m)
+	return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+      if (!is_lb_static_mapping (m))
+	return VNET_API_ERROR_INVALID_VALUE;
+
+      /* Free external address port */
+      if (!(sm->static_mapping_only || out2in_only))
+	{
+	  for (i = 0; i < vec_len (sm->addresses); i++)
+	    {
+	      if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+		{
+		  a = sm->addresses + i;
+		  switch (proto)
+		    {
+#define _(N, j, n, s) \
+                    case NAT_PROTOCOL_##N: \
+                      --a->busy_##n##_port_refcounts[e_port]; \
+                      if (e_port > 1024) \
+                        { \
+                          a->busy_##n##_ports--; \
+                          a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]--; \
+                        } \
+                      break;
+		      foreach_nat_protocol
+#undef _
+			default : nat_elog_info (sm, "unknown protocol");
+		      return VNET_API_ERROR_INVALID_VALUE_2;
+		    }
+		  break;
+		}
+	    }
+	}
+
+      init_nat_k (&kv, m->external_addr, m->external_port, 0, m->proto);
+      if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0))
+	{
+	  nat_elog_err (sm, "static_mapping_by_external key del failed");
+	  return VNET_API_ERROR_UNSPECIFIED;
+	}
+
+      /* *INDENT-OFF* */
+      pool_foreach (local, m->locals)
+      {
+          fib_table_unlock (local->fib_index, FIB_PROTOCOL_IP4,
+                            sm->fib_src_low);
+          if (!out2in_only)
+            {
+init_nat_k(&              kv, local->addr, local->port, local->fib_index, m->proto);
+              if (clib_bihash_add_del_8_8(&sm->static_mapping_by_local, &kv, 0))
+                {
+		  nat_elog_err (sm, "static_mapping_by_local key del failed");
+		  return VNET_API_ERROR_UNSPECIFIED;
+		}
+	    }
+
+	  if (sm->num_workers > 1)
+	    {
+	      ip4_header_t ip = {
+		.src_address = local->addr,
+	      };
+	      tsm =
+		vec_elt_at_index (sm->per_thread_data,
+				  sm->worker_in2out_cb (&ip, m->fib_index, 0));
+	    }
+	  else
+	    tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+	  /* Delete sessions */
+	  pool_foreach (s, tsm->sessions)
+	    {
+	      if (!(is_lb_session (s)))
+		continue;
+
+	      if ((s->in2out.addr.as_u32 != local->addr.as_u32) ||
+		  s->in2out.port != local->port)
+		continue;
+
+	      nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
+	      nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+	    }
+      }
+      /* *INDENT-ON* */
+      if (m->affinity)
+	nat_affinity_flush_service (m->affinity_per_service_list_head_index);
+      pool_free (m->locals);
+      vec_free (m->tag);
+      vec_free (m->workers);
+
+      pool_put (sm->static_mappings, m);
+    }
+
+  return 0;
+}
+
+int
+nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
+				       ip4_address_t l_addr, u16 l_port,
+				       nat_protocol_t proto, u32 vrf_id,
+				       u8 probability, u8 is_add)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_mapping_t *m = 0;
+  clib_bihash_kv_8_8_t kv, value;
+  nat44_lb_addr_port_t *local, *prev_local, *match_local = 0;
+  snat_main_per_thread_data_t *tsm;
+  snat_session_t *s;
+  u32 *locals = 0;
+  uword *bitmap = 0;
+  int i;
+
+  init_nat_k (&kv, e_addr, e_port, 0, proto);
+  if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (!m)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+  if (!is_lb_static_mapping (m))
+    return VNET_API_ERROR_INVALID_VALUE;
+
+  /* *INDENT-OFF* */
+  pool_foreach (local, m->locals)
+   {
+    if ((local->addr.as_u32 == l_addr.as_u32) && (local->port == l_port) &&
+        (local->vrf_id == vrf_id))
+      {
+        match_local = local;
+        break;
+      }
+  }
+  /* *INDENT-ON* */
+
+  if (is_add)
+    {
+      if (match_local)
+	return VNET_API_ERROR_VALUE_EXIST;
+
+      pool_get (m->locals, local);
+      clib_memset (local, 0, sizeof (*local));
+      local->addr.as_u32 = l_addr.as_u32;
+      local->port = l_port;
+      local->probability = probability;
+      local->vrf_id = vrf_id;
+      local->fib_index =
+	fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
+					   sm->fib_src_low);
+
+      if (!is_out2in_only_static_mapping (m))
+	{
+	  init_nat_kv (&kv, l_addr, l_port, local->fib_index, proto, 0,
+		       m - sm->static_mappings);
+	  if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1))
+	    nat_elog_err (sm, "static_mapping_by_local key add failed");
+	}
+    }
+  else
+    {
+      if (!match_local)
+	return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+      if (pool_elts (m->locals) < 3)
+	return VNET_API_ERROR_UNSPECIFIED;
+
+      fib_table_unlock (match_local->fib_index, FIB_PROTOCOL_IP4,
+			sm->fib_src_low);
+
+      if (!is_out2in_only_static_mapping (m))
+	{
+	  init_nat_k (&kv, l_addr, l_port, match_local->fib_index, proto);
+	  if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0))
+	    nat_elog_err (sm, "static_mapping_by_local key del failed");
+	}
+
+      if (sm->num_workers > 1)
+	{
+	  ip4_header_t ip = {
+	    .src_address = local->addr,
+	  };
+	  tsm = vec_elt_at_index (sm->per_thread_data,
+				  sm->worker_in2out_cb (&ip, m->fib_index,
+							0));
+	}
+      else
+	tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+      /* Delete sessions */
+      /* *INDENT-OFF* */
+      pool_foreach (s, tsm->sessions) {
+        if (!(is_lb_session (s)))
+          continue;
+
+        if ((s->in2out.addr.as_u32 != match_local->addr.as_u32) ||
+            s->in2out.port != match_local->port)
+          continue;
+
+        nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
+        nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+      }
+      /* *INDENT-ON* */
+
+      pool_put (m->locals, match_local);
+    }
+
+  vec_free (m->workers);
+
+  /* *INDENT-OFF* */
+  pool_foreach (local, m->locals)
+   {
+    vec_add1 (locals, local - m->locals);
+    if (sm->num_workers > 1)
+      {
+        ip4_header_t ip;
+        ip.src_address.as_u32 = local->addr.as_u32,
+        bitmap = clib_bitmap_set (bitmap,
+                                  sm->worker_in2out_cb (&ip, local->fib_index, 0),
+                                  1);
+      }
+  }
+  /* *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++)
+    {
+      local = pool_elt_at_index (m->locals, locals[i]);
+      prev_local = pool_elt_at_index (m->locals, locals[i - 1]);
+      local->prefix = local->probability + prev_local->prefix;
+    }
+
+  /* Assign workers */
+  if (sm->num_workers > 1)
+    {
+      /* *INDENT-OFF* */
+      clib_bitmap_foreach (i, bitmap)  { vec_add1(m->workers, i); }
+      /* *INDENT-ON* */
+    }
+
+  return 0;
+}
+
+int
+snat_del_address (snat_main_t * sm, ip4_address_t addr, u8 delete_sm,
+		  u8 twice_nat)
+{
+  snat_address_t *a = 0;
+  snat_session_t *ses;
+  u32 *ses_to_be_removed = 0, *ses_index;
+  snat_main_per_thread_data_t *tsm;
+  snat_static_mapping_t *m;
+  snat_interface_t *interface;
+  int i;
+  snat_address_t *addresses =
+    twice_nat ? sm->twice_nat_addresses : sm->addresses;
+
+  /* Find SNAT address */
+  for (i = 0; i < vec_len (addresses); i++)
+    {
+      if (addresses[i].addr.as_u32 == addr.as_u32)
+	{
+	  a = addresses + i;
+	  break;
+	}
+    }
+  if (!a)
+    {
+      nat_log_err ("no such address");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
+
+  if (delete_sm)
+    {
+      ip4_address_t pool_addr = { 0 };
+      /* *INDENT-OFF* */
+      pool_foreach (m, sm->static_mappings)
+       {
+          if (m->external_addr.as_u32 == addr.as_u32)
+            (void) snat_add_static_mapping (m->local_addr, m->external_addr,
+                                            m->local_port, m->external_port,
+                                            m->vrf_id,
+                                            is_addr_only_static_mapping(m), ~0,
+                                            m->proto, 0 /* is_add */,
+                                            m->twice_nat,
+                                            is_out2in_only_static_mapping(m),
+                                            m->tag,
+                                            is_identity_static_mapping(m),
+                                            pool_addr, 0);
+      }
+      /* *INDENT-ON* */
+    }
+  else
+    {
+      /* Check if address is used in some static mapping */
+      if (is_snat_address_used_in_static_mapping (sm, addr))
+	{
+	  nat_log_err ("address used in static mapping");
+	  return VNET_API_ERROR_UNSPECIFIED;
+	}
+    }
+
+  if (a->fib_index != ~0)
+    fib_table_unlock (a->fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+
+  /* Delete sessions using address */
+  if (a->busy_tcp_ports || a->busy_udp_ports || a->busy_icmp_ports)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+      {
+        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, 0);
+              vec_add1 (ses_to_be_removed, ses - tsm->sessions);
+            }
+        }
+
+	    vec_foreach (ses_index, ses_to_be_removed)
+	    {
+	      ses = pool_elt_at_index (tsm->sessions, ses_index[0]);
+	      nat_ed_session_delete (sm, ses, tsm - sm->per_thread_data, 1);
+	    }
+
+	vec_free (ses_to_be_removed);
+      }
+    }
+
+#define _(N, i, n, s) \
+  vec_free (a->busy_##n##_ports_per_thread);
+  foreach_nat_protocol
+#undef _
+
+    if (twice_nat)
+  {
+    vec_del1 (sm->twice_nat_addresses, i);
+    return 0;
+  }
+  else vec_del1 (sm->addresses, i);
+
+  /* Delete external address from FIB */
+  pool_foreach (interface, sm->interfaces)
+    {
+      if (nat_interface_is_inside (interface))
+	continue;
+
+      snat_add_del_addr_to_fib (&addr, 32, interface->sw_if_index, 0);
+      break;
+    }
+  pool_foreach (interface, sm->output_feature_interfaces)
+   {
+     if (nat_interface_is_inside (interface))
+       continue;
+
+     snat_add_del_addr_to_fib (&addr, 32, interface->sw_if_index, 0);
+     break;
+  }
+
+  return 0;
+}
+
+void
+expire_per_vrf_sessions (u32 fib_index)
+{
+  per_vrf_sessions_t *per_vrf_sessions;
+  snat_main_per_thread_data_t *tsm;
+  snat_main_t *sm = &snat_main;
+
+  /* *INDENT-OFF* */
+  vec_foreach (tsm, sm->per_thread_data)
+    {
+      vec_foreach (per_vrf_sessions, tsm->per_vrf_sessions_vec)
+        {
+          if ((per_vrf_sessions->rx_fib_index == fib_index) ||
+              (per_vrf_sessions->tx_fib_index == fib_index))
+            {
+              per_vrf_sessions->expired = 1;
+            }
+        }
+    }
+  /* *INDENT-ON* */
+}
+
+void
+update_per_vrf_sessions_vec (u32 fib_index, int is_del)
+{
+  snat_main_t *sm = &snat_main;
+  nat_fib_t *fib;
+
+  // we don't care if it is outside/inside fib
+  // we just care about their ref_count
+  // if it reaches 0 sessions should expire
+  // because the fib isn't valid for NAT anymore
+
+  vec_foreach (fib, sm->fibs)
+  {
+    if (fib->fib_index == fib_index)
+      {
+	if (is_del)
+	  {
+	    fib->ref_count--;
+	    if (!fib->ref_count)
+	      {
+		vec_del1 (sm->fibs, fib - sm->fibs);
+		expire_per_vrf_sessions (fib_index);
+	      }
+	    return;
+	  }
+	else
+	  fib->ref_count++;
+      }
+  }
+  if (!is_del)
+    {
+      vec_add2 (sm->fibs, fib, 1);
+      fib->ref_count = 1;
+      fib->fib_index = fib_index;
+    }
+}
+
+int
+snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
+{
+  snat_main_t *sm = &snat_main;
+  snat_interface_t *i;
+  const char *feature_name, *del_feature_name;
+  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->enabled)
+    {
+      nat_log_err ("nat44 is disabled");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
+
+  /* *INDENT-OFF* */
+  pool_foreach (i, sm->output_feature_interfaces)
+   {
+    if (i->sw_if_index == sw_if_index)
+      {
+        nat_log_err ("error interface already configured");
+        return VNET_API_ERROR_VALUE_EXIST;
+      }
+  }
+  /* *INDENT-ON* */
+
+  if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
+    feature_name = is_inside ? "nat44-in2out-fast" : "nat44-out2in-fast";
+  else
+    {
+      if (sm->num_workers > 1)
+	feature_name =
+	  is_inside ? "nat44-in2out-worker-handoff" :
+	  "nat44-out2in-worker-handoff";
+      else
+	feature_name = is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+    }
+
+  ASSERT (sm->frame_queue_nelts > 0);
+
+  if (sm->fq_in2out_index == ~0 && sm->num_workers > 1)
+    sm->fq_in2out_index = vlib_frame_queue_main_init (sm->in2out_node_index,
+						      sm->frame_queue_nelts);
+
+  if (sm->fq_out2in_index == ~0 && sm->num_workers > 1)
+    sm->fq_out2in_index = vlib_frame_queue_main_init (sm->out2in_node_index,
+						      sm->frame_queue_nelts);
+
+  update_per_vrf_sessions_vec (fib_index, is_del);
+
+  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:
+  /* *INDENT-OFF* */
+  pool_foreach (i, sm->interfaces)
+   {
+    if (i->sw_if_index == sw_if_index)
+      {
+        if (is_del)
+          {
+            if (nat_interface_is_inside(i) && nat_interface_is_outside(i))
+              {
+                if (is_inside)
+                  i->flags &= ~NAT_INTERFACE_FLAG_IS_INSIDE;
+                else
+                  i->flags &= ~NAT_INTERFACE_FLAG_IS_OUTSIDE;
+
+                if (sm->num_workers > 1)
+                  {
+                    del_feature_name = "nat44-handoff-classify";
+                    feature_name = !is_inside ?  "nat44-in2out-worker-handoff" :
+                                                 "nat44-out2in-worker-handoff";
+                  }
+		else
+		  {
+		    del_feature_name = "nat44-ed-classify";
+		    feature_name =
+		      !is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+		  }
+
+		int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
+		if (rv)
+		  return rv;
+                vnet_feature_enable_disable ("ip4-unicast", del_feature_name,
+                                             sw_if_index, 0, 0, 0);
+                vnet_feature_enable_disable ("ip4-unicast", feature_name,
+                                             sw_if_index, 1, 0, 0);
+	      }
+	    else
+	      {
+		int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
+		if (rv)
+		  return rv;
+                vnet_feature_enable_disable ("ip4-unicast", feature_name,
+                                             sw_if_index, 0, 0, 0);
+                pool_put (sm->interfaces, i);
+	      }
+	  }
+	else
+	  {
+	    if ((nat_interface_is_inside (i) && is_inside) ||
+		(nat_interface_is_outside (i) && !is_inside))
+	      return 0;
+
+	    if (sm->num_workers > 1)
+	      {
+		del_feature_name = !is_inside ? "nat44-in2out-worker-handoff" :
+						"nat44-out2in-worker-handoff";
+		feature_name = "nat44-handoff-classify";
+	      }
+	    else
+	      {
+		del_feature_name =
+		  !is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+
+		feature_name = "nat44-ed-classify";
+	      }
+
+	    int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
+	    if (rv)
+	      return rv;
+            vnet_feature_enable_disable ("ip4-unicast", del_feature_name,
+                                         sw_if_index, 0, 0, 0);
+            vnet_feature_enable_disable ("ip4-unicast", feature_name,
+                                         sw_if_index, 1, 0, 0);
+	    goto set_flags;
+	  }
+
+	goto fib;
+      }
+  }
+  /* *INDENT-ON* */
+
+  if (is_del)
+    {
+      nat_log_err ("error interface couldn't be found");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
+
+  pool_get (sm->interfaces, i);
+  i->sw_if_index = sw_if_index;
+  i->flags = 0;
+  nat_validate_interface_counters (sm, sw_if_index);
+
+  vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index, 1, 0,
+			       0);
+
+  int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
+  if (rv)
+    return rv;
+
+set_flags:
+  if (is_inside)
+    {
+      i->flags |= NAT_INTERFACE_FLAG_IS_INSIDE;
+      return 0;
+    }
+  else
+    i->flags |= NAT_INTERFACE_FLAG_IS_OUTSIDE;
+
+  /* Add/delete external addresses to FIB */
+fib:
+  /* *INDENT-OFF* */
+  vec_foreach (ap, sm->addresses)
+    snat_add_del_addr_to_fib(&ap->addr, 32, sw_if_index, !is_del);
+
+  pool_foreach (m, sm->static_mappings)
+   {
+    if (!(is_addr_only_static_mapping(m)) || (m->local_addr.as_u32 == m->external_addr.as_u32))
+      continue;
+
+    snat_add_del_addr_to_fib(&m->external_addr, 32, sw_if_index, !is_del);
+  }
+  /* *INDENT-ON* */
+
+  return 0;
+}
+
+int
+snat_interface_add_del_output_feature (u32 sw_if_index,
+				       u8 is_inside, int is_del)
+{
+  snat_main_t *sm = &snat_main;
+  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->enabled)
+    {
+      nat_log_err ("nat44 is disabled");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
+
+  if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
+    {
+      nat_log_err ("error unsupported");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
+
+  /* *INDENT-OFF* */
+  pool_foreach (i, sm->interfaces)
+   {
+    if (i->sw_if_index == sw_if_index)
+      {
+        nat_log_err ("error interface already configured");
+        return VNET_API_ERROR_VALUE_EXIST;
+      }
+  }
+  /* *INDENT-ON* */
+
+  update_per_vrf_sessions_vec (fib_index, is_del);
+
+  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)
+    {
+	  int rv =
+	    ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, !is_del);
+	  if (rv)
+	    return rv;
+	  rv =
+	    ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index,
+							    !is_del);
+	  if (rv)
+	    return rv;
+      goto fq;
+    }
+
+  if (sm->num_workers > 1)
+    {
+      int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, !is_del);
+      if (rv)
+	return rv;
+      rv =
+	ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index, !is_del);
+      if (rv)
+	return rv;
+      vnet_feature_enable_disable ("ip4-unicast",
+				   "nat44-out2in-worker-handoff",
+				   sw_if_index, !is_del, 0, 0);
+      vnet_feature_enable_disable ("ip4-output",
+				   "nat44-in2out-output-worker-handoff",
+				   sw_if_index, !is_del, 0, 0);
+    }
+  else
+    {
+	  int rv =
+	    ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, !is_del);
+	  if (rv)
+	    return rv;
+	  rv =
+	    ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index,
+							    !is_del);
+	  if (rv)
+	    return rv;
+	  vnet_feature_enable_disable ("ip4-unicast", "nat-pre-out2in",
+				       sw_if_index, !is_del, 0, 0);
+	  vnet_feature_enable_disable ("ip4-output", "nat-pre-in2out-output",
+				       sw_if_index, !is_del, 0, 0);
+    }
+
+fq:
+  if (sm->fq_in2out_output_index == ~0 && sm->num_workers > 1)
+    sm->fq_in2out_output_index =
+      vlib_frame_queue_main_init (sm->in2out_output_node_index, 0);
+
+  if (sm->fq_out2in_index == ~0 && sm->num_workers > 1)
+    sm->fq_out2in_index =
+      vlib_frame_queue_main_init (sm->out2in_node_index, 0);
+
+  /* *INDENT-OFF* */
+  pool_foreach (i, sm->output_feature_interfaces)
+   {
+    if (i->sw_if_index == sw_if_index)
+      {
+        if (is_del)
+          pool_put (sm->output_feature_interfaces, i);
+        else
+          return VNET_API_ERROR_VALUE_EXIST;
+
+        goto fib;
+      }
+  }
+  /* *INDENT-ON* */
+
+  if (is_del)
+    {
+      nat_log_err ("error interface couldn't be found");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
+
+  pool_get (sm->output_feature_interfaces, i);
+  i->sw_if_index = sw_if_index;
+  i->flags = 0;
+  nat_validate_interface_counters (sm, sw_if_index);
+  if (is_inside)
+    i->flags |= NAT_INTERFACE_FLAG_IS_INSIDE;
+  else
+    i->flags |= NAT_INTERFACE_FLAG_IS_OUTSIDE;
+
+  /* Add/delete external addresses to FIB */
+fib:
+  if (is_inside)
+    return 0;
+
+  /* *INDENT-OFF* */
+  vec_foreach (ap, sm->addresses)
+    snat_add_del_addr_to_fib(&ap->addr, 32, sw_if_index, !is_del);
+
+  pool_foreach (m, sm->static_mappings)
+   {
+    if (!((is_addr_only_static_mapping(m)))  || (m->local_addr.as_u32 == m->external_addr.as_u32))
+      continue;
+
+    snat_add_del_addr_to_fib(&m->external_addr, 32, sw_if_index, !is_del);
+  }
+  /* *INDENT-ON* */
+
+  return 0;
+}
+
+int
+snat_set_workers (uword * bitmap)
+{
+  snat_main_t *sm = &snat_main;
+  int i, j = 0;
+
+  if (sm->num_workers < 2)
+    return VNET_API_ERROR_FEATURE_DISABLED;
+
+  if (clib_bitmap_last_set (bitmap) >= sm->num_workers)
+    return VNET_API_ERROR_INVALID_WORKER;
+
+  vec_free (sm->workers);
+  /* *INDENT-OFF* */
+  clib_bitmap_foreach (i, bitmap)
+    {
+      vec_add1(sm->workers, i);
+      sm->per_thread_data[sm->first_worker_index + i].snat_thread_index = j;
+      sm->per_thread_data[sm->first_worker_index + i].thread_index = i;
+      j++;
+    }
+  /* *INDENT-ON* */
+
+  sm->port_per_thread = (0xffff - 1024) / _vec_len (sm->workers);
+
+  return 0;
+}
+
+int
+nat44_ed_set_frame_queue_nelts (u32 frame_queue_nelts)
+{
+  fail_if_enabled ();
+  snat_main_t *sm = &snat_main;
+  sm->frame_queue_nelts = frame_queue_nelts;
+  return 0;
+}
+
+static void
+snat_update_outside_fib (ip4_main_t * im, uword opaque,
+			 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;
+  u8 match = 0;
+
+  if (!sm->enabled || (new_fib_index == old_fib_index)
+      || (!vec_len (sm->outside_fibs)))
+    {
+      return;
+    }
+
+  /* *INDENT-OFF* */
+  pool_foreach (i, sm->interfaces)
+     {
+      if (i->sw_if_index == sw_if_index)
+        {
+          if (!(nat_interface_is_outside (i)))
+	    return;
+          match = 1;
+        }
+    }
+
+  pool_foreach (i, sm->output_feature_interfaces)
+     {
+      if (i->sw_if_index == sw_if_index)
+        {
+          if (!(nat_interface_is_outside (i)))
+	    return;
+          match = 1;
+        }
+    }
+  /* *INDENT-ON* */
+
+  if (!match)
+    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_update_outside_fib (ip4_main_t * im, uword opaque,
+			 u32 sw_if_index, u32 new_fib_index,
+			 u32 old_fib_index);
+
+static void
+snat_ip4_add_del_interface_address_cb (ip4_main_t * im,
+				       uword opaque,
+				       u32 sw_if_index,
+				       ip4_address_t * address,
+				       u32 address_length,
+				       u32 if_address_index, u32 is_delete);
+
+static void
+nat_ip4_add_del_addr_only_sm_cb (ip4_main_t * im,
+				 uword opaque,
+				 u32 sw_if_index,
+				 ip4_address_t * address,
+				 u32 address_length,
+				 u32 if_address_index, u32 is_delete);
+
+void
+test_key_calc_split ()
+{
+  ip4_address_t l_addr;
+  l_addr.as_u8[0] = 1;
+  l_addr.as_u8[1] = 1;
+  l_addr.as_u8[2] = 1;
+  l_addr.as_u8[3] = 1;
+  ip4_address_t r_addr;
+  r_addr.as_u8[0] = 2;
+  r_addr.as_u8[1] = 2;
+  r_addr.as_u8[2] = 2;
+  r_addr.as_u8[3] = 2;
+  u16 l_port = 40001;
+  u16 r_port = 40301;
+  u8 proto = 9;
+  u32 fib_index = 9000001;
+  u32 thread_index = 3000000001;
+  u32 session_index = 3000000221;
+  clib_bihash_kv_16_8_t kv;
+  init_ed_kv (&kv, l_addr, l_port, r_addr, r_port, fib_index, proto,
+	      thread_index, session_index);
+  ip4_address_t l_addr2;
+  ip4_address_t r_addr2;
+  clib_memset (&l_addr2, 0, sizeof (l_addr2));
+  clib_memset (&r_addr2, 0, sizeof (r_addr2));
+  u16 l_port2 = 0;
+  u16 r_port2 = 0;
+  u8 proto2 = 0;
+  u32 fib_index2 = 0;
+  split_ed_kv (&kv, &l_addr2, &r_addr2, &proto2, &fib_index2, &l_port2,
+	       &r_port2);
+  ASSERT (l_addr.as_u32 == l_addr2.as_u32);
+  ASSERT (r_addr.as_u32 == r_addr2.as_u32);
+  ASSERT (l_port == l_port2);
+  ASSERT (r_port == r_port2);
+  ASSERT (proto == proto2);
+  ASSERT (fib_index == fib_index2);
+  ASSERT (thread_index == ed_value_get_thread_index (&kv));
+  ASSERT (session_index == ed_value_get_session_index (&kv));
+
+  fib_index = 7001;
+  proto = 5;
+  nat_protocol_t proto3 = ~0;
+  u64 key = calc_nat_key (l_addr, l_port, fib_index, proto);
+  split_nat_key (key, &l_addr2, &l_port2, &fib_index2, &proto3);
+  ASSERT (l_addr.as_u32 == l_addr2.as_u32);
+  ASSERT (l_port == l_port2);
+  ASSERT (proto == proto3);
+  ASSERT (fib_index == fib_index2);
+}
+
+static clib_error_t *
+nat_ip_table_add_del (vnet_main_t * vnm, u32 table_id, u32 is_add)
+{
+  u32 fib_index;
+
+      // TODO: consider removing all NAT interfaces
+      if (!is_add)
+	{
+	  fib_index = ip4_fib_index_from_table_id (table_id);
+	  if (fib_index != ~0)
+	    expire_per_vrf_sessions (fib_index);
+	}
+  return 0;
+}
+
+VNET_IP_TABLE_ADD_DEL_FUNCTION (nat_ip_table_add_del);
+
+void
+nat44_set_node_indexes (snat_main_t * sm, vlib_main_t * vm)
+{
+  vlib_node_t *node;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-out2in");
+  sm->in2out_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out");
+  sm->out2in_node_index = node->index;
+
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out-output");
+  sm->in2out_output_node_index = node->index;
+}
+
+#define nat_validate_simple_counter(c, i)                                     \
+  do                                                                          \
+    {                                                                         \
+      vlib_validate_simple_counter (&c, i);                                   \
+      vlib_zero_simple_counter (&c, i);                                       \
+    }                                                                         \
+  while (0);
+
+#define nat_init_simple_counter(c, n, sn)                                     \
+  do                                                                          \
+    {                                                                         \
+      c.name = n;                                                             \
+      c.stat_segment_name = sn;                                               \
+      nat_validate_simple_counter (c, 0);                                     \
+    }                                                                         \
+  while (0);
+
+static_always_inline void
+nat_validate_interface_counters (snat_main_t *sm, u32 sw_if_index)
+{
+#define _(x)                                                                  \
+  nat_validate_simple_counter (sm->counters.fastpath.in2out.x, sw_if_index);  \
+  nat_validate_simple_counter (sm->counters.fastpath.out2in.x, sw_if_index);  \
+  nat_validate_simple_counter (sm->counters.slowpath.in2out.x, sw_if_index);  \
+  nat_validate_simple_counter (sm->counters.slowpath.out2in.x, sw_if_index);
+  foreach_nat_counter;
+#undef _
+  nat_validate_simple_counter (sm->counters.hairpinning, sw_if_index);
+}
+
+static clib_error_t *
+nat_init (vlib_main_t * vm)
+{
+  snat_main_t *sm = &snat_main;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+  vlib_thread_registration_t *tr;
+  ip4_add_del_interface_address_callback_t cbi = { 0 };
+  ip4_table_bind_callback_t cbt = { 0 };
+  u32 i, num_threads = 0;
+  uword *p, *bitmap = 0;
+
+  clib_memset (sm, 0, sizeof (*sm));
+
+  // required
+  sm->vnet_main = vnet_get_main ();
+  // convenience
+  sm->ip4_main = &ip4_main;
+  sm->api_main = vlibapi_get_main ();
+  sm->ip4_lookup_main = &ip4_main.lookup_main;
+
+  // frame queue indices used for handoff
+  sm->fq_out2in_index = ~0;
+  sm->fq_in2out_index = ~0;
+  sm->fq_in2out_output_index = ~0;
+
+  sm->log_level = NAT_LOG_ERROR;
+
+  nat44_set_node_indexes (sm, vm);
+  sm->log_class = vlib_log_register_class ("nat", 0);
+  nat_ipfix_logging_init (vm);
+
+  nat_init_simple_counter (sm->total_sessions, "total-sessions",
+			   "/nat44-ed/total-sessions");
+
+#define _(x)                                                                  \
+  nat_init_simple_counter (sm->counters.fastpath.in2out.x, #x,                \
+			   "/nat44-ed/in2out/fastpath/" #x);                  \
+  nat_init_simple_counter (sm->counters.fastpath.out2in.x, #x,                \
+			   "/nat44-ed/out2in/fastpath/" #x);                  \
+  nat_init_simple_counter (sm->counters.slowpath.in2out.x, #x,                \
+			   "/nat44-ed/in2out/slowpath/" #x);                  \
+  nat_init_simple_counter (sm->counters.slowpath.out2in.x, #x,                \
+			   "/nat44-ed/out2in/slowpath/" #x);
+  foreach_nat_counter;
+#undef _
+  nat_init_simple_counter (sm->counters.hairpinning, "hairpinning",
+			   "/nat44-ed/hairpinning");
+
+  p = hash_get_mem (tm->thread_registrations_by_name, "workers");
+  if (p)
+    {
+      tr = (vlib_thread_registration_t *) p[0];
+      if (tr)
+	{
+	  sm->num_workers = tr->count;
+	  sm->first_worker_index = tr->first_index;
+	}
+    }
+  num_threads = tm->n_vlib_mains - 1;
+  sm->port_per_thread = 0xffff - 1024;
+  vec_validate (sm->per_thread_data, num_threads);
+
+  /* Use all available workers by default */
+  if (sm->num_workers > 1)
+    {
+
+      for (i = 0; i < sm->num_workers; i++)
+	bitmap = clib_bitmap_set (bitmap, i, 1);
+      snat_set_workers (bitmap);
+      clib_bitmap_free (bitmap);
+    }
+  else
+    sm->per_thread_data[0].snat_thread_index = 0;
+
+  /* callbacks to call when interface address changes. */
+  cbi.function = snat_ip4_add_del_interface_address_cb;
+  vec_add1 (sm->ip4_main->add_del_interface_address_callbacks, cbi);
+  cbi.function = nat_ip4_add_del_addr_only_sm_cb;
+  vec_add1 (sm->ip4_main->add_del_interface_address_callbacks, cbi);
+
+  /* callbacks to call when interface to table biding changes */
+  cbt.function = snat_update_outside_fib;
+  vec_add1 (sm->ip4_main->table_bind_callbacks, cbt);
+
+  sm->fib_src_low =
+    fib_source_allocate ("nat-low", FIB_SOURCE_PRIORITY_LOW,
+			 FIB_SOURCE_BH_SIMPLE);
+  sm->fib_src_hi =
+    fib_source_allocate ("nat-hi", FIB_SOURCE_PRIORITY_HI,
+			 FIB_SOURCE_BH_SIMPLE);
+
+  nat_affinity_init (vm);
+  test_key_calc_split ();
+
+  return nat44_api_hookup (vm);
+}
+
+VLIB_INIT_FUNCTION (nat_init);
+
+int
+nat44_plugin_enable (nat44_config_t c)
+{
+  snat_main_t *sm = &snat_main;
+
+  fail_if_enabled ();
+
+  // UPDATE based on these appropriate API/CLI
+  // c.static_mapping_only + c.connection_tracking
+  //  - supported in NAT EI & NAT ED
+  // c.out2in_dpo, c.static_mapping_only
+  //  - supported in NAT EI
+
+  if (c.static_mapping_only && !c.connection_tracking)
+    {
+      nat_log_err ("unsupported combination of configuration");
+      return 1;
+    }
+
+  // nat44 feature configuration
+  sm->static_mapping_only = c.static_mapping_only;
+  sm->static_mapping_connection_tracking = c.connection_tracking;
+
+  sm->forwarding_enabled = 0;
+  sm->mss_clamping = 0;
+  sm->pat = (!c.static_mapping_only ||
+	     (c.static_mapping_only && c.connection_tracking));
+
+  if (!c.sessions)
+    c.sessions = 63 * 1024;
+
+  sm->max_translations_per_thread = c.sessions;
+  sm->translation_buckets = nat_calc_bihash_buckets (c.sessions);
+
+  // ED only feature
+  vec_add1 (sm->max_translations_per_fib, sm->max_translations_per_thread);
+
+  sm->inside_vrf_id = c.inside_vrf;
+  sm->inside_fib_index =
+    fib_table_find_or_create_and_lock
+    (FIB_PROTOCOL_IP4, c.inside_vrf, sm->fib_src_hi);
+
+  sm->outside_vrf_id = c.outside_vrf;
+  sm->outside_fib_index = fib_table_find_or_create_and_lock (
+    FIB_PROTOCOL_IP4, c.outside_vrf, sm->fib_src_hi);
+
+  sm->worker_in2out_cb = nat44_ed_get_worker_in2out_cb;
+  sm->worker_out2in_cb = nat44_ed_get_worker_out2in_cb;
+
+  nat44_ed_db_init (sm->max_translations_per_thread, sm->translation_buckets);
+
+  nat_affinity_enable ();
+
+  nat_reset_timeouts (&sm->timeouts);
+
+  vlib_zero_simple_counter (&sm->total_sessions, 0);
+
+  if (!sm->frame_queue_nelts)
+    sm->frame_queue_nelts = NAT_FQ_NELTS_DEFAULT;
+
+  sm->enabled = 1;
+  sm->rconfig = c;
+
+  return 0;
+}
+
+void
+nat44_addresses_free (snat_address_t ** addresses)
+{
+  snat_address_t *ap;
+  vec_foreach (ap, *addresses)
+    {
+    #define _(N, i, n, s) \
+      vec_free (ap->busy_##n##_ports_per_thread);
+      foreach_nat_protocol
+    #undef _
+    }
+  vec_free (*addresses);
+  *addresses = 0;
+}
+
+int
+nat44_plugin_disable ()
+{
+  snat_main_t *sm = &snat_main;
+  snat_interface_t *i, *vec;
+  int error = 0;
+
+  fail_if_disabled ();
+
+  // first unregister all nodes from interfaces
+  vec = vec_dup (sm->interfaces);
+  vec_foreach (i, vec)
+    {
+      if (nat_interface_is_inside(i))
+        error = snat_interface_add_del (i->sw_if_index, 1, 1);
+      if (nat_interface_is_outside(i))
+        error = snat_interface_add_del (i->sw_if_index, 0, 1);
+
+      if (error)
+        {
+          nat_log_err ("error occurred while removing interface %u",
+                       i->sw_if_index);
+        }
+    }
+  vec_free (vec);
+  sm->interfaces = 0;
+
+  vec = vec_dup (sm->output_feature_interfaces);
+  vec_foreach (i, vec)
+    {
+      if (nat_interface_is_inside(i))
+        error = snat_interface_add_del_output_feature (i->sw_if_index, 1, 1);
+      if (nat_interface_is_outside(i))
+        error = snat_interface_add_del_output_feature (i->sw_if_index, 0, 1);
+
+      if (error)
+        {
+          nat_log_err ("error occurred while removing interface %u",
+                       i->sw_if_index);
+        }
+    }
+  vec_free (vec);
+  sm->output_feature_interfaces = 0;
+
+  vec_free (sm->max_translations_per_fib);
+
+  nat44_ed_db_free ();
+
+  nat44_addresses_free (&sm->addresses);
+  nat44_addresses_free (&sm->twice_nat_addresses);
+
+  vec_free (sm->to_resolve);
+  vec_free (sm->auto_add_sw_if_indices);
+  vec_free (sm->auto_add_sw_if_indices_twice_nat);
+
+  sm->to_resolve = 0;
+  sm->auto_add_sw_if_indices = 0;
+  sm->auto_add_sw_if_indices_twice_nat = 0;
+
+  sm->forwarding_enabled = 0;
+
+  sm->enabled = 0;
+  clib_memset (&sm->rconfig, 0, sizeof (sm->rconfig));
+
+  return 0;
+}
+
+void
+nat44_ed_forwarding_enable_disable (u8 is_enable)
+{
+  snat_main_per_thread_data_t *tsm;
+  snat_main_t *sm = &snat_main;
+  snat_session_t *s;
+
+  u32 *ses_to_be_removed = 0, *ses_index;
+
+  sm->forwarding_enabled = is_enable != 0;
+
+  if (is_enable)
+    return;
+
+  vec_foreach (tsm, sm->per_thread_data)
+    {
+      pool_foreach (s, tsm->sessions)
+	{
+	  if (is_fwd_bypass_session (s))
+	    {
+	      vec_add1 (ses_to_be_removed, s - tsm->sessions);
+	    }
+	}
+      vec_foreach (ses_index, ses_to_be_removed)
+	{
+	  s = pool_elt_at_index (tsm->sessions, ses_index[0]);
+	  nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
+	  nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+	}
+
+      vec_free (ses_to_be_removed);
+    }
+}
+
+void
+snat_free_outside_address_and_port (snat_address_t *addresses,
+				    u32 thread_index, ip4_address_t *addr,
+				    u16 port, nat_protocol_t protocol)
+{
+  snat_main_t *sm = &snat_main;
+  snat_address_t *a;
+  u32 address_index;
+  u16 port_host_byte_order = clib_net_to_host_u16 (port);
+
+  for (address_index = 0; address_index < vec_len (addresses);
+       address_index++)
+    {
+      if (addresses[address_index].addr.as_u32 == addr->as_u32)
+	break;
+    }
+
+  ASSERT (address_index < vec_len (addresses));
+
+  a = addresses + address_index;
+
+  switch (protocol)
+    {
+#define _(N, i, n, s) \
+    case NAT_PROTOCOL_##N: \
+      ASSERT (a->busy_##n##_port_refcounts[port_host_byte_order] >= 1); \
+      --a->busy_##n##_port_refcounts[port_host_byte_order]; \
+      a->busy_##n##_ports--; \
+      a->busy_##n##_ports_per_thread[thread_index]--; \
+      break;
+      foreach_nat_protocol
+#undef _
+	default : nat_elog_info (sm, "unknown protocol");
+      return;
+    }
+}
+
+int
+nat_set_outside_address_and_port (snat_address_t *addresses, u32 thread_index,
+				  ip4_address_t addr, u16 port,
+				  nat_protocol_t protocol)
+{
+  snat_main_t *sm = &snat_main;
+  snat_address_t *a = 0;
+  u32 address_index;
+  u16 port_host_byte_order = clib_net_to_host_u16 (port);
+
+  for (address_index = 0; address_index < vec_len (addresses);
+       address_index++)
+    {
+      if (addresses[address_index].addr.as_u32 != addr.as_u32)
+	continue;
+
+      a = addresses + address_index;
+      switch (protocol)
+	{
+#define _(N, j, n, s) \
+        case NAT_PROTOCOL_##N: \
+          if (a->busy_##n##_port_refcounts[port_host_byte_order]) \
+            return VNET_API_ERROR_INSTANCE_IN_USE; \
+	  ++a->busy_##n##_port_refcounts[port_host_byte_order]; \
+          a->busy_##n##_ports_per_thread[thread_index]++; \
+          a->busy_##n##_ports++; \
+          return 0;
+	  foreach_nat_protocol
+#undef _
+	    default : nat_elog_info (sm, "unknown protocol");
+	  return 1;
+	}
+    }
+
+  return VNET_API_ERROR_NO_SUCH_ENTRY;
+}
+
+int
+snat_static_mapping_match (snat_main_t * sm,
+			   ip4_address_t match_addr,
+			   u16 match_port,
+			   u32 match_fib_index,
+			   nat_protocol_t match_protocol,
+			   ip4_address_t * mapping_addr,
+			   u16 * mapping_port,
+			   u32 * mapping_fib_index,
+			   u8 by_external,
+			   u8 * is_addr_only,
+			   twice_nat_type_t * twice_nat,
+			   lb_nat_type_t * lb, ip4_address_t * ext_host_addr,
+			   u8 * is_identity_nat, snat_static_mapping_t ** out)
+{
+  clib_bihash_kv_8_8_t kv, value;
+  clib_bihash_8_8_t *mapping_hash;
+  snat_static_mapping_t *m;
+  u32 rand, lo = 0, hi, mid, *tmp = 0, i;
+  nat44_lb_addr_port_t *local;
+  u8 backend_index;
+
+  if (!by_external)
+    {
+      mapping_hash = &sm->static_mapping_by_local;
+      init_nat_k (&kv, match_addr, match_port, match_fib_index,
+		  match_protocol);
+      if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+	{
+	  /* Try address only mapping */
+	  init_nat_k (&kv, match_addr, 0, match_fib_index, 0);
+	  if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+	    return 1;
+	}
+    }
+  else
+    {
+      mapping_hash = &sm->static_mapping_by_external;
+      init_nat_k (&kv, match_addr, match_port, 0, match_protocol);
+      if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+	{
+	  /* Try address only mapping */
+	  init_nat_k (&kv, match_addr, 0, 0, 0);
+	  if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+	    return 1;
+	}
+    }
+
+  m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (by_external)
+    {
+      if (is_lb_static_mapping (m))
+	{
+	  if (PREDICT_FALSE (lb != 0))
+	    *lb = m->affinity ? AFFINITY_LB_NAT : LB_NAT;
+	  if (m->affinity && !nat_affinity_find_and_lock (ext_host_addr[0],
+							  match_addr,
+							  match_protocol,
+							  match_port,
+							  &backend_index))
+	    {
+	      local = pool_elt_at_index (m->locals, backend_index);
+	      *mapping_addr = local->addr;
+	      *mapping_port = local->port;
+	      *mapping_fib_index = local->fib_index;
+	      goto end;
+	    }
+	  // pick locals matching this worker
+	  if (PREDICT_FALSE (sm->num_workers > 1))
+	    {
+	      u32 thread_index = vlib_get_thread_index ();
+              pool_foreach_index (i, m->locals)
+               {
+                local = pool_elt_at_index (m->locals, i);
+
+                ip4_header_t ip = {
+		  .src_address = local->addr,
+	        };
+
+	        if (sm->worker_in2out_cb (&ip, m->fib_index, 0) ==
+		    thread_index)
+                  {
+                    vec_add1 (tmp, i);
+                  }
+              }
+	      ASSERT (vec_len (tmp) != 0);
+	    }
+	  else
+	    {
+              pool_foreach_index (i, m->locals)
+               {
+                vec_add1 (tmp, i);
+              }
+	    }
+	  hi = vec_len (tmp) - 1;
+	  local = pool_elt_at_index (m->locals, tmp[hi]);
+	  rand = 1 + (random_u32 (&sm->random_seed) % local->prefix);
+	  while (lo < hi)
+	    {
+	      mid = ((hi - lo) >> 1) + lo;
+	      local = pool_elt_at_index (m->locals, tmp[mid]);
+	      (rand > local->prefix) ? (lo = mid + 1) : (hi = mid);
+	    }
+	  local = pool_elt_at_index (m->locals, tmp[lo]);
+	  if (!(local->prefix >= rand))
+	    return 1;
+	  *mapping_addr = local->addr;
+	  *mapping_port = local->port;
+	  *mapping_fib_index = local->fib_index;
+	  if (m->affinity)
+	    {
+	      if (nat_affinity_create_and_lock (ext_host_addr[0], match_addr,
+						match_protocol, match_port,
+						tmp[lo], m->affinity,
+						m->affinity_per_service_list_head_index))
+		nat_elog_info (sm, "create affinity record failed");
+	    }
+	  vec_free (tmp);
+	}
+      else
+	{
+	  if (PREDICT_FALSE (lb != 0))
+	    *lb = NO_LB_NAT;
+	  *mapping_fib_index = m->fib_index;
+	  *mapping_addr = m->local_addr;
+	  /* Address only mapping doesn't change port */
+	  *mapping_port = is_addr_only_static_mapping (m) ? match_port
+	    : m->local_port;
+	}
+    }
+  else
+    {
+      *mapping_addr = m->external_addr;
+      /* Address only mapping doesn't change port */
+      *mapping_port = is_addr_only_static_mapping (m) ? match_port
+	: m->external_port;
+      *mapping_fib_index = sm->outside_fib_index;
+    }
+
+end:
+  if (PREDICT_FALSE (is_addr_only != 0))
+    *is_addr_only = is_addr_only_static_mapping (m);
+
+  if (PREDICT_FALSE (twice_nat != 0))
+    *twice_nat = m->twice_nat;
+
+  if (PREDICT_FALSE (is_identity_nat != 0))
+    *is_identity_nat = is_identity_static_mapping (m);
+
+  if (out != 0)
+    *out = m;
+
+  return 0;
+}
+
+static u32
+nat44_ed_get_worker_in2out_cb (ip4_header_t *ip, u32 rx_fib_index,
+			       u8 is_output)
+{
+  snat_main_t *sm = &snat_main;
+  u32 next_worker_index = sm->first_worker_index;
+  u32 hash;
+
+  clib_bihash_kv_16_8_t kv16, value16;
+  snat_main_per_thread_data_t *tsm;
+  udp_header_t *udp;
+
+  if (PREDICT_FALSE (is_output))
+    {
+      u32 fib_index = sm->outside_fib_index;
+      nat_outside_fib_t *outside_fib;
+      fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
+      fib_prefix_t pfx = {
+	.fp_proto = FIB_PROTOCOL_IP4,
+	.fp_len = 32,
+	.fp_addr = {
+		    .ip4.as_u32 = ip->dst_address.as_u32,
+		    }
+	,
+      };
+
+      udp = ip4_next_header (ip);
+
+      switch (vec_len (sm->outside_fibs))
+	{
+	case 0:
+	  fib_index = sm->outside_fib_index;
+	  break;
+	case 1:
+	  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)
+                      {
+                        fib_index = outside_fib->fib_index;
+                        break;
+                      }
+                  }
+              }
+            /* *INDENT-ON* */
+	  break;
+	}
+
+      init_ed_k (&kv16, ip->src_address, udp->src_port, ip->dst_address,
+		 udp->dst_port, fib_index, ip->protocol);
+
+      if (PREDICT_TRUE (
+	    !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+	{
+	  tsm =
+	    vec_elt_at_index (sm->per_thread_data,
+			      ed_value_get_thread_index (&value16));
+	  next_worker_index += tsm->thread_index;
+
+	  nat_elog_debug_handoff (
+	    sm, "HANDOFF IN2OUT-OUTPUT-FEATURE (session)", next_worker_index,
+	    fib_index, clib_net_to_host_u32 (ip->src_address.as_u32),
+	    clib_net_to_host_u32 (ip->dst_address.as_u32));
+
+	  return next_worker_index;
+	}
+    }
+
+  hash = ip->src_address.as_u32 + (ip->src_address.as_u32 >> 8) +
+    (ip->src_address.as_u32 >> 16) + (ip->src_address.as_u32 >> 24);
+
+  if (PREDICT_TRUE (is_pow2 (_vec_len (sm->workers))))
+    next_worker_index += sm->workers[hash & (_vec_len (sm->workers) - 1)];
+  else
+    next_worker_index += sm->workers[hash % _vec_len (sm->workers)];
+
+  if (PREDICT_TRUE (!is_output))
+    {
+      nat_elog_debug_handoff (sm, "HANDOFF IN2OUT", next_worker_index,
+			      rx_fib_index,
+			      clib_net_to_host_u32 (ip->src_address.as_u32),
+			      clib_net_to_host_u32 (ip->dst_address.as_u32));
+    }
+  else
+    {
+      nat_elog_debug_handoff (sm, "HANDOFF IN2OUT-OUTPUT-FEATURE",
+			      next_worker_index, rx_fib_index,
+			      clib_net_to_host_u32 (ip->src_address.as_u32),
+			      clib_net_to_host_u32 (ip->dst_address.as_u32));
+    }
+
+  return next_worker_index;
+}
+
+static u32
+nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
+			       u32 rx_fib_index, u8 is_output)
+{
+  snat_main_t *sm = &snat_main;
+  clib_bihash_kv_8_8_t kv, value;
+  clib_bihash_kv_16_8_t kv16, value16;
+  snat_main_per_thread_data_t *tsm;
+
+  u32 proto, next_worker_index = 0;
+  udp_header_t *udp;
+  u16 port;
+  snat_static_mapping_t *m;
+  u32 hash;
+
+  proto = ip_proto_to_nat_proto (ip->protocol);
+
+  if (PREDICT_TRUE (proto == NAT_PROTOCOL_UDP || proto == NAT_PROTOCOL_TCP))
+    {
+      udp = ip4_next_header (ip);
+
+      init_ed_k (&kv16, ip->dst_address, udp->dst_port, ip->src_address,
+		 udp->src_port, rx_fib_index, ip->protocol);
+
+      if (PREDICT_TRUE (
+	    !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+	{
+	  tsm =
+	    vec_elt_at_index (sm->per_thread_data,
+			      ed_value_get_thread_index (&value16));
+	  vnet_buffer2 (b)->nat.cached_session_index =
+	    ed_value_get_session_index (&value16);
+	  next_worker_index = sm->first_worker_index + tsm->thread_index;
+	  nat_elog_debug_handoff (
+	    sm, "HANDOFF OUT2IN (session)", next_worker_index, rx_fib_index,
+	    clib_net_to_host_u32 (ip->src_address.as_u32),
+	    clib_net_to_host_u32 (ip->dst_address.as_u32));
+	  return next_worker_index;
+	}
+    }
+  else if (proto == NAT_PROTOCOL_ICMP)
+    {
+      ip4_address_t lookup_saddr, lookup_daddr;
+      u16 lookup_sport, lookup_dport;
+      u8 lookup_protocol;
+      if (!nat_get_icmp_session_lookup_values (
+	    b, ip, &lookup_saddr, &lookup_sport, &lookup_daddr, &lookup_dport,
+	    &lookup_protocol))
+	{
+	  init_ed_k (&kv16, lookup_saddr, lookup_sport, lookup_daddr,
+		     lookup_dport, rx_fib_index, lookup_protocol);
+	  if (PREDICT_TRUE (
+		!clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+	    {
+	      tsm =
+		vec_elt_at_index (sm->per_thread_data,
+				  ed_value_get_thread_index (&value16));
+	      next_worker_index = sm->first_worker_index + tsm->thread_index;
+	      nat_elog_debug_handoff (
+		sm, "HANDOFF OUT2IN (session)", next_worker_index,
+		rx_fib_index, clib_net_to_host_u32 (ip->src_address.as_u32),
+		clib_net_to_host_u32 (ip->dst_address.as_u32));
+	      return next_worker_index;
+	    }
+	}
+    }
+
+  /* first try static mappings without port */
+  if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
+    {
+      init_nat_k (&kv, ip->dst_address, 0, 0, 0);
+      if (!clib_bihash_search_8_8
+	  (&sm->static_mapping_by_external, &kv, &value))
+	{
+	  m = pool_elt_at_index (sm->static_mappings, value.value);
+	  next_worker_index = m->workers[0];
+	  goto done;
+	}
+    }
+
+  /* unknown protocol */
+  if (PREDICT_FALSE (proto == NAT_PROTOCOL_OTHER))
+    {
+      /* use current thread */
+      next_worker_index = vlib_get_thread_index ();
+      goto done;
+    }
+
+  udp = ip4_next_header (ip);
+  port = udp->dst_port;
+
+  if (PREDICT_FALSE (ip->protocol == IP_PROTOCOL_ICMP))
+    {
+      icmp46_header_t *icmp = (icmp46_header_t *) udp;
+      icmp_echo_header_t *echo = (icmp_echo_header_t *) (icmp + 1);
+      if (!icmp_type_is_error_message
+	  (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags))
+	port = vnet_buffer (b)->ip.reass.l4_src_port;
+      else
+	{
+	  /* if error message, then it's not fragmented and we can access it */
+	  ip4_header_t *inner_ip = (ip4_header_t *) (echo + 1);
+	  proto = ip_proto_to_nat_proto (inner_ip->protocol);
+	  void *l4_header = ip4_next_header (inner_ip);
+	  switch (proto)
+	    {
+	    case NAT_PROTOCOL_ICMP:
+	      icmp = (icmp46_header_t *) l4_header;
+	      echo = (icmp_echo_header_t *) (icmp + 1);
+	      port = echo->identifier;
+	      break;
+	    case NAT_PROTOCOL_UDP:
+	    case NAT_PROTOCOL_TCP:
+	      port = ((tcp_udp_header_t *) l4_header)->src_port;
+	      break;
+	    default:
+	      next_worker_index = vlib_get_thread_index ();
+	      goto done;
+	    }
+	}
+    }
+
+  /* try static mappings with port */
+  if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
+    {
+      init_nat_k (&kv, ip->dst_address, port, 0, proto);
+      if (!clib_bihash_search_8_8
+	  (&sm->static_mapping_by_external, &kv, &value))
+	{
+	  m = pool_elt_at_index (sm->static_mappings, value.value);
+	  if (!is_lb_static_mapping (m))
+	    {
+	      next_worker_index = m->workers[0];
+	      goto done;
+	    }
+
+	  hash = ip->src_address.as_u32 + (ip->src_address.as_u32 >> 8) +
+	    (ip->src_address.as_u32 >> 16) + (ip->src_address.as_u32 >> 24);
+
+	  if (PREDICT_TRUE (is_pow2 (_vec_len (m->workers))))
+	    next_worker_index =
+	      m->workers[hash & (_vec_len (m->workers) - 1)];
+	  else
+	    next_worker_index = m->workers[hash % _vec_len (m->workers)];
+	  goto done;
+	}
+    }
+
+  /* worker by outside port */
+  next_worker_index = sm->first_worker_index;
+  next_worker_index +=
+    sm->workers[(clib_net_to_host_u16 (port) - 1024) / sm->port_per_thread];
+
+done:
+  nat_elog_debug_handoff (sm, "HANDOFF OUT2IN", next_worker_index,
+			  rx_fib_index,
+			  clib_net_to_host_u32 (ip->src_address.as_u32),
+			  clib_net_to_host_u32 (ip->dst_address.as_u32));
+  return next_worker_index;
+}
+
+u32
+nat44_get_max_session_limit ()
+{
+  snat_main_t *sm = &snat_main;
+  u32 max_limit = 0, len = 0;
+
+  for (; len < vec_len (sm->max_translations_per_fib); len++)
+    {
+      if (max_limit < sm->max_translations_per_fib[len])
+	max_limit = sm->max_translations_per_fib[len];
+    }
+  return max_limit;
+}
+
+int
+nat44_set_session_limit (u32 session_limit, u32 vrf_id)
+{
+  snat_main_t *sm = &snat_main;
+  u32 fib_index = fib_table_find (FIB_PROTOCOL_IP4, vrf_id);
+  u32 len = vec_len (sm->max_translations_per_fib);
+
+  if (len <= fib_index)
+    {
+      vec_validate (sm->max_translations_per_fib, fib_index + 1);
+
+      for (; len < vec_len (sm->max_translations_per_fib); len++)
+	sm->max_translations_per_fib[len] = sm->max_translations_per_thread;
+    }
+
+  sm->max_translations_per_fib[fib_index] = session_limit;
+  return 0;
+}
+
+int
+nat44_update_session_limit (u32 session_limit, u32 vrf_id)
+{
+  snat_main_t *sm = &snat_main;
+
+  if (nat44_set_session_limit (session_limit, vrf_id))
+    return 1;
+  sm->max_translations_per_thread = nat44_get_max_session_limit ();
+
+  sm->translation_buckets =
+    nat_calc_bihash_buckets (sm->max_translations_per_thread);
+
+  nat44_ed_sessions_clear ();
+  return 0;
+}
+
+static void
+nat44_ed_worker_db_init (snat_main_per_thread_data_t *tsm, u32 translations,
+			 u32 translation_buckets)
+{
+  dlist_elt_t *head;
+
+  pool_alloc (tsm->sessions, translations);
+  pool_alloc (tsm->lru_pool, translations);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->tcp_trans_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->tcp_trans_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->tcp_estab_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->tcp_estab_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->udp_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->udp_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->icmp_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->icmp_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->unk_proto_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->unk_proto_lru_head_index);
+}
+
+static void
+reinit_ed_flow_hash ()
+{
+  snat_main_t *sm = &snat_main;
+  // we expect 2 flows per session, so multiply translation_buckets by 2
+  clib_bihash_init_16_8 (
+    &sm->flow_hash, "ed-flow-hash",
+    clib_max (1, sm->num_workers) * 2 * sm->translation_buckets, 0);
+  clib_bihash_set_kvp_format_fn_16_8 (&sm->flow_hash, format_ed_session_kvp);
+}
+
+static void
+nat44_ed_db_init (u32 translations, u32 translation_buckets)
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+  u32 static_mapping_buckets = 1024;
+  u32 static_mapping_memory_size = 64 << 20;
+
+  reinit_ed_flow_hash ();
+
+  clib_bihash_init_8_8 (&sm->static_mapping_by_local,
+			"static_mapping_by_local", static_mapping_buckets,
+			static_mapping_memory_size);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_local,
+				     format_static_mapping_kvp);
+
+  clib_bihash_init_8_8 (&sm->static_mapping_by_external,
+			"static_mapping_by_external", static_mapping_buckets,
+			static_mapping_memory_size);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_external,
+				     format_static_mapping_kvp);
+
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+	  nat44_ed_worker_db_init (tsm, sm->max_translations_per_thread,
+				   sm->translation_buckets);
+	}
+    }
+}
+
+static void
+nat44_ed_worker_db_free (snat_main_per_thread_data_t *tsm)
+{
+  pool_free (tsm->lru_pool);
+  pool_free (tsm->sessions);
+  vec_free (tsm->per_vrf_sessions_vec);
+}
+
+static void
+nat44_ed_db_free ()
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+
+  pool_free (sm->static_mappings);
+  clib_bihash_free_16_8 (&sm->flow_hash);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_local);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_external);
+
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+	  nat44_ed_worker_db_free (tsm);
+	}
+    }
+}
+
+void
+nat44_ed_sessions_clear ()
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+
+  reinit_ed_flow_hash ();
+
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+
+	  nat44_ed_worker_db_free (tsm);
+	  nat44_ed_worker_db_init (tsm, sm->max_translations_per_thread,
+				   sm->translation_buckets);
+	}
+    }
+  vlib_zero_simple_counter (&sm->total_sessions, 0);
+}
+
+static void
+nat_ip4_add_del_addr_only_sm_cb (ip4_main_t * im,
+				 uword opaque,
+				 u32 sw_if_index,
+				 ip4_address_t * address,
+				 u32 address_length,
+				 u32 if_address_index, u32 is_delete)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_map_resolve_t *rp;
+  snat_static_mapping_t *m;
+  clib_bihash_kv_8_8_t kv, value;
+  int i, rv;
+  ip4_address_t l_addr;
+
+  if (!sm->enabled)
+    return;
+
+  for (i = 0; i < vec_len (sm->to_resolve); i++)
+    {
+      rp = sm->to_resolve + i;
+      if (rp->addr_only == 0)
+	continue;
+      if (rp->sw_if_index == sw_if_index)
+	goto match;
+    }
+
+  return;
+
+match:
+  init_nat_k (&kv, *address, rp->addr_only ? 0 : rp->e_port,
+	      sm->outside_fib_index, rp->addr_only ? 0 : rp->proto);
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    m = 0;
+  else
+    m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (!is_delete)
+    {
+      /* Don't trip over lease renewal, static config */
+      if (m)
+	return;
+    }
+  else
+    {
+      if (!m)
+	return;
+    }
+
+  /* Indetity mapping? */
+  if (rp->l_addr.as_u32 == 0)
+    l_addr.as_u32 = address[0].as_u32;
+  else
+    l_addr.as_u32 = rp->l_addr.as_u32;
+  /* Add the static mapping */
+  rv = snat_add_static_mapping (l_addr,
+				address[0],
+				rp->l_port,
+				rp->e_port,
+				rp->vrf_id,
+				rp->addr_only, ~0 /* sw_if_index */ ,
+				rp->proto, !is_delete, rp->twice_nat,
+				rp->out2in_only, rp->tag, rp->identity_nat,
+				rp->pool_addr, rp->exact);
+  if (rv)
+    nat_elog_notice_X1 (sm, "snat_add_static_mapping returned %d", "i4", rv);
+}
+
+static void
+snat_ip4_add_del_interface_address_cb (ip4_main_t * im,
+				       uword opaque,
+				       u32 sw_if_index,
+				       ip4_address_t * address,
+				       u32 address_length,
+				       u32 if_address_index, u32 is_delete)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_map_resolve_t *rp;
+  ip4_address_t l_addr;
+  int i, j;
+  int rv;
+  u8 twice_nat = 0;
+  snat_address_t *addresses = sm->addresses;
+
+  if (!sm->enabled)
+    return;
+
+  for (i = 0; i < vec_len (sm->auto_add_sw_if_indices); i++)
+    {
+      if (sw_if_index == sm->auto_add_sw_if_indices[i])
+	goto match;
+    }
+
+  for (i = 0; i < vec_len (sm->auto_add_sw_if_indices_twice_nat); i++)
+    {
+      twice_nat = 1;
+      addresses = sm->twice_nat_addresses;
+      if (sw_if_index == sm->auto_add_sw_if_indices_twice_nat[i])
+	goto match;
+    }
+
+  return;
+
+match:
+  if (!is_delete)
+    {
+      /* Don't trip over lease renewal, static config */
+      for (j = 0; j < vec_len (addresses); j++)
+	if (addresses[j].addr.as_u32 == address->as_u32)
+	  return;
+
+      (void) snat_add_address (sm, address, ~0, twice_nat);
+      /* Scan static map resolution vector */
+      for (j = 0; j < vec_len (sm->to_resolve); j++)
+	{
+	  rp = sm->to_resolve + j;
+	  if (rp->addr_only)
+	    continue;
+	  /* On this interface? */
+	  if (rp->sw_if_index == sw_if_index)
+	    {
+	      /* Indetity mapping? */
+	      if (rp->l_addr.as_u32 == 0)
+		l_addr.as_u32 = address[0].as_u32;
+	      else
+		l_addr.as_u32 = rp->l_addr.as_u32;
+	      /* Add the static mapping */
+	      rv = snat_add_static_mapping (
+		l_addr, address[0], rp->l_port, rp->e_port, rp->vrf_id,
+		rp->addr_only, ~0 /* sw_if_index */, rp->proto, 1,
+		rp->twice_nat, rp->out2in_only, rp->tag, rp->identity_nat,
+		rp->pool_addr, rp->exact);
+	      if (rv)
+		nat_elog_notice_X1 (sm, "snat_add_static_mapping returned %d",
+				    "i4", rv);
+	    }
+	}
+      return;
+    }
+  else
+    {
+      (void) snat_del_address (sm, address[0], 1, twice_nat);
+      return;
+    }
+}
+
+int
+snat_add_interface_address (snat_main_t * sm, u32 sw_if_index, int is_del,
+			    u8 twice_nat)
+{
+  ip4_main_t *ip4_main = sm->ip4_main;
+  ip4_address_t *first_int_addr;
+  snat_static_map_resolve_t *rp;
+  u32 *indices_to_delete = 0;
+  int i, j;
+  u32 *auto_add_sw_if_indices =
+    twice_nat ? sm->
+    auto_add_sw_if_indices_twice_nat : sm->auto_add_sw_if_indices;
+
+  first_int_addr = ip4_interface_first_address (ip4_main, sw_if_index, 0	/* just want the address */
+    );
+
+  for (i = 0; i < vec_len (auto_add_sw_if_indices); i++)
+    {
+      if (auto_add_sw_if_indices[i] == sw_if_index)
+	{
+	  if (is_del)
+	    {
+	      /* if have address remove it */
+	      if (first_int_addr)
+		(void) snat_del_address (sm, first_int_addr[0], 1, twice_nat);
+	      else
+		{
+		  for (j = 0; j < vec_len (sm->to_resolve); j++)
+		    {
+		      rp = sm->to_resolve + j;
+		      if (rp->sw_if_index == sw_if_index)
+			vec_add1 (indices_to_delete, j);
+		    }
+		  if (vec_len (indices_to_delete))
+		    {
+		      for (j = vec_len (indices_to_delete) - 1; j >= 0; j--)
+			vec_del1 (sm->to_resolve, j);
+		      vec_free (indices_to_delete);
+		    }
+		}
+	      if (twice_nat)
+		vec_del1 (sm->auto_add_sw_if_indices_twice_nat, i);
+	      else
+		vec_del1 (sm->auto_add_sw_if_indices, i);
+	    }
+	  else
+	    return VNET_API_ERROR_VALUE_EXIST;
+
+	  return 0;
+	}
+    }
+
+  if (is_del)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+  /* add to the auto-address list */
+  if (twice_nat)
+    vec_add1 (sm->auto_add_sw_if_indices_twice_nat, sw_if_index);
+  else
+    vec_add1 (sm->auto_add_sw_if_indices, sw_if_index);
+
+  /* If the address is already bound - or static - add it now */
+  if (first_int_addr)
+    (void) snat_add_address (sm, first_int_addr, ~0, twice_nat);
+
+  return 0;
+}
+
+int
+nat44_del_ed_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
+		      ip4_address_t * eh_addr, u16 eh_port, u8 proto,
+		      u32 vrf_id, int is_in)
+{
+  ip4_header_t ip;
+  clib_bihash_kv_16_8_t kv, value;
+  u32 fib_index = fib_table_find (FIB_PROTOCOL_IP4, vrf_id);
+  snat_session_t *s;
+  snat_main_per_thread_data_t *tsm;
+
+  ip.dst_address.as_u32 = ip.src_address.as_u32 = addr->as_u32;
+  if (sm->num_workers > 1)
+    tsm =
+      vec_elt_at_index (sm->per_thread_data,
+			sm->worker_in2out_cb (&ip, fib_index, 0));
+  else
+    tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+  init_ed_k (&kv, *addr, port, *eh_addr, eh_port, fib_index, proto);
+  if (clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
+    {
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
+
+  if (pool_is_free_index (tsm->sessions, ed_value_get_session_index (&value)))
+    return VNET_API_ERROR_UNSPECIFIED;
+  s = pool_elt_at_index (tsm->sessions, ed_value_get_session_index (&value));
+  nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
+  nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+  return 0;
+}
+
+VLIB_NODE_FN (nat_default_node) (vlib_main_t * vm,
+				 vlib_node_runtime_t * node,
+				 vlib_frame_t * frame)
+{
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat_default_node) = {
+  .name = "nat-default",
+  .vector_size = sizeof (u32),
+  .format_trace = 0,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = 0,
+  .n_next_nodes = NAT_N_NEXT,
+  .next_nodes = {
+    [NAT_NEXT_DROP] = "error-drop",
+    [NAT_NEXT_ICMP_ERROR] = "ip4-icmp-error",
+    [NAT_NEXT_IN2OUT_ED_FAST_PATH] = "nat44-ed-in2out",
+    [NAT_NEXT_IN2OUT_ED_SLOW_PATH] = "nat44-ed-in2out-slowpath",
+    [NAT_NEXT_IN2OUT_ED_OUTPUT_FAST_PATH] = "nat44-ed-in2out-output",
+    [NAT_NEXT_IN2OUT_ED_OUTPUT_SLOW_PATH] = "nat44-ed-in2out-output-slowpath",
+    [NAT_NEXT_OUT2IN_ED_FAST_PATH] = "nat44-ed-out2in",
+    [NAT_NEXT_OUT2IN_ED_SLOW_PATH] = "nat44-ed-out2in-slowpath",
+    [NAT_NEXT_IN2OUT_CLASSIFY] = "nat44-in2out-worker-handoff",
+    [NAT_NEXT_OUT2IN_CLASSIFY] = "nat44-out2in-worker-handoff",
+  },
+};
+/* *INDENT-ON* */
+
+void
+nat_6t_l3_l4_csum_calc (nat_6t_flow_t *f)
+{
+  f->l3_csum_delta = 0;
+  f->l4_csum_delta = 0;
+  if (f->ops & NAT_FLOW_OP_SADDR_REWRITE &&
+      f->rewrite.saddr.as_u32 != f->match.saddr.as_u32)
+    {
+      f->l3_csum_delta =
+	ip_csum_add_even (f->l3_csum_delta, f->rewrite.saddr.as_u32);
+      f->l3_csum_delta =
+	ip_csum_sub_even (f->l3_csum_delta, f->match.saddr.as_u32);
+    }
+  else
+    {
+      f->rewrite.saddr.as_u32 = f->match.saddr.as_u32;
+    }
+  if (f->ops & NAT_FLOW_OP_DADDR_REWRITE &&
+      f->rewrite.daddr.as_u32 != f->match.daddr.as_u32)
+    {
+      f->l3_csum_delta =
+	ip_csum_add_even (f->l3_csum_delta, f->rewrite.daddr.as_u32);
+      f->l3_csum_delta =
+	ip_csum_sub_even (f->l3_csum_delta, f->match.daddr.as_u32);
+    }
+  else
+    {
+      f->rewrite.daddr.as_u32 = f->match.daddr.as_u32;
+    }
+  if (f->ops & NAT_FLOW_OP_SPORT_REWRITE && f->rewrite.sport != f->match.sport)
+    {
+      f->l4_csum_delta = ip_csum_add_even (f->l4_csum_delta, f->rewrite.sport);
+      f->l4_csum_delta = ip_csum_sub_even (f->l4_csum_delta, f->match.sport);
+    }
+  else
+    {
+      f->rewrite.sport = f->match.sport;
+    }
+  if (f->ops & NAT_FLOW_OP_DPORT_REWRITE && f->rewrite.dport != f->match.dport)
+    {
+      f->l4_csum_delta = ip_csum_add_even (f->l4_csum_delta, f->rewrite.dport);
+      f->l4_csum_delta = ip_csum_sub_even (f->l4_csum_delta, f->match.dport);
+    }
+  else
+    {
+      f->rewrite.dport = f->match.dport;
+    }
+  if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE &&
+      f->rewrite.icmp_id != f->match.icmp_id)
+    {
+      f->l4_csum_delta =
+	ip_csum_add_even (f->l4_csum_delta, f->rewrite.icmp_id);
+      f->l4_csum_delta = ip_csum_sub_even (f->l4_csum_delta, f->match.icmp_id);
+    }
+  else
+    {
+      f->rewrite.icmp_id = f->match.icmp_id;
+    }
+  if (f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
+    {
+    }
+  else
+    {
+      f->rewrite.fib_index = f->match.fib_index;
+    }
+}
+
+static_always_inline int nat_6t_flow_icmp_translate (snat_main_t *sm,
+						     vlib_buffer_t *b,
+						     ip4_header_t *ip,
+						     nat_6t_flow_t *f);
+
+static_always_inline void
+nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
+			   nat_6t_flow_t *f, nat_protocol_t proto,
+			   int is_icmp_inner_ip4)
+{
+  udp_header_t *udp = ip4_next_header (ip);
+  tcp_header_t *tcp = (tcp_header_t *) udp;
+
+  if ((NAT_PROTOCOL_TCP == proto || NAT_PROTOCOL_UDP == proto) &&
+      !vnet_buffer (b)->ip.reass.is_non_first_fragment)
+    {
+      if (!is_icmp_inner_ip4)
+	{ // regular case
+	  ip->src_address = f->rewrite.saddr;
+	  ip->dst_address = f->rewrite.daddr;
+	  udp->src_port = f->rewrite.sport;
+	  udp->dst_port = f->rewrite.dport;
+	}
+      else
+	{ // icmp inner ip4 - reversed saddr/daddr
+	  ip->src_address = f->rewrite.daddr;
+	  ip->dst_address = f->rewrite.saddr;
+	  udp->src_port = f->rewrite.dport;
+	  udp->dst_port = f->rewrite.sport;
+	}
+
+      if (NAT_PROTOCOL_TCP == proto)
+	{
+	  ip_csum_t tcp_sum = tcp->checksum;
+	  tcp_sum = ip_csum_sub_even (tcp_sum, f->l3_csum_delta);
+	  tcp_sum = ip_csum_sub_even (tcp_sum, f->l4_csum_delta);
+	  mss_clamping (sm->mss_clamping, tcp, &tcp_sum);
+	  tcp->checksum = ip_csum_fold (tcp_sum);
+	}
+      else if (proto == NAT_PROTOCOL_UDP && udp->checksum)
+	{
+	  ip_csum_t udp_sum = udp->checksum;
+	  udp_sum = ip_csum_sub_even (udp_sum, f->l3_csum_delta);
+	  udp_sum = ip_csum_sub_even (udp_sum, f->l4_csum_delta);
+	  udp->checksum = ip_csum_fold (udp_sum);
+	}
+    }
+  else
+    {
+      if (!is_icmp_inner_ip4)
+	{ // regular case
+	  ip->src_address = f->rewrite.saddr;
+	  ip->dst_address = f->rewrite.daddr;
+	}
+      else
+	{ // icmp inner ip4 - reversed saddr/daddr
+	  ip->src_address = f->rewrite.daddr;
+	  ip->dst_address = f->rewrite.saddr;
+	}
+    }
+
+  ip_csum_t ip_sum = ip->checksum;
+  ip_sum = ip_csum_sub_even (ip_sum, f->l3_csum_delta);
+  ip->checksum = ip_csum_fold (ip_sum);
+  ASSERT (ip->checksum == ip4_header_checksum (ip));
+}
+
+static_always_inline int
+nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
+			    ip4_header_t *ip, nat_6t_flow_t *f)
+{
+  if (IP_PROTOCOL_ICMP != ip->protocol)
+    return NAT_ED_TRNSL_ERR_TRANSLATION_FAILED;
+
+  icmp46_header_t *icmp = ip4_next_header (ip);
+  icmp_echo_header_t *echo = (icmp_echo_header_t *) (icmp + 1);
+
+  if ((!vnet_buffer (b)->ip.reass.is_non_first_fragment))
+    {
+      if (icmp->checksum == 0)
+	icmp->checksum = 0xffff;
+
+      if (!icmp_type_is_error_message (icmp->type))
+	{
+	  if ((f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE) &&
+	      (f->rewrite.icmp_id != echo->identifier))
+	    {
+	      ip_csum_t sum = icmp->checksum;
+	      sum = ip_csum_update (sum, echo->identifier, f->rewrite.icmp_id,
+				    icmp_echo_header_t,
+				    identifier /* changed member */);
+	      echo->identifier = f->rewrite.icmp_id;
+	      icmp->checksum = ip_csum_fold (sum);
+	    }
+	}
+      else
+	{
+	  // errors are not fragmented
+	  ip4_header_t *inner_ip = (ip4_header_t *) (echo + 1);
+
+	  if (!ip4_header_checksum_is_valid (inner_ip))
+	    {
+	      return NAT_ED_TRNSL_ERR_TRANSLATION_FAILED;
+	    }
+
+	  nat_protocol_t inner_proto =
+	    ip_proto_to_nat_proto (inner_ip->protocol);
+
+	  ip_csum_t icmp_sum = icmp->checksum;
+
+	  switch (inner_proto)
+	    {
+	    case NAT_PROTOCOL_UDP:
+	    case NAT_PROTOCOL_TCP:
+	      nat_6t_flow_ip4_translate (sm, b, inner_ip, f, inner_proto,
+					 1 /* is_icmp_inner_ip4 */);
+	      icmp_sum = ip_csum_sub_even (icmp_sum, f->l3_csum_delta);
+	      icmp->checksum = ip_csum_fold (icmp_sum);
+	      break;
+	    case NAT_PROTOCOL_ICMP:
+	      if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE)
+		{
+		  icmp46_header_t *inner_icmp = ip4_next_header (inner_ip);
+		  icmp_echo_header_t *inner_echo =
+		    (icmp_echo_header_t *) (inner_icmp + 1);
+		  if (f->rewrite.icmp_id != inner_echo->identifier)
+		    {
+		      ip_csum_t sum = icmp->checksum;
+		      sum = ip_csum_update (
+			sum, inner_echo->identifier, f->rewrite.icmp_id,
+			icmp_echo_header_t, identifier /* changed member */);
+		      icmp->checksum = ip_csum_fold (sum);
+		      ip_csum_t inner_sum = inner_icmp->checksum;
+		      inner_sum = ip_csum_update (
+			sum, inner_echo->identifier, f->rewrite.icmp_id,
+			icmp_echo_header_t, identifier /* changed member */);
+		      inner_icmp->checksum = ip_csum_fold (inner_sum);
+		      inner_echo->identifier = f->rewrite.icmp_id;
+		    }
+		}
+	      break;
+	    default:
+	      clib_warning ("unexpected NAT protocol value `%d'", inner_proto);
+	      return NAT_ED_TRNSL_ERR_TRANSLATION_FAILED;
+	    }
+	}
+    }
+  return NAT_ED_TRNSL_ERR_SUCCESS;
+}
+
+nat_translation_error_e
+nat_6t_flow_buf_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
+			   nat_6t_flow_t *f, nat_protocol_t proto,
+			   int is_output_feature)
+{
+  if (!is_output_feature && f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
+    {
+      vnet_buffer (b)->sw_if_index[VLIB_TX] = f->rewrite.fib_index;
+    }
+
+  nat_6t_flow_ip4_translate (sm, b, ip, f, proto, 0 /* is_icmp_inner_ip4 */);
+
+  if (NAT_PROTOCOL_ICMP == proto)
+    {
+      return nat_6t_flow_icmp_translate (sm, b, ip, f);
+    }
+
+  return NAT_ED_TRNSL_ERR_SUCCESS;
+}
+
+u8 *
+format_nat_6t (u8 *s, va_list *args)
+{
+  nat_6t_t *t = va_arg (*args, nat_6t_t *);
+
+  s = format (s, "saddr %U sport %u daddr %U dport %u proto %U fib_idx %u",
+	      format_ip4_address, t->saddr.as_u8,
+	      clib_net_to_host_u16 (t->sport), format_ip4_address,
+	      t->daddr.as_u8, clib_net_to_host_u16 (t->dport),
+	      format_ip_protocol, t->proto, t->fib_index);
+  return s;
+}
+
+u8 *
+format_nat_ed_translation_error (u8 *s, va_list *args)
+{
+  nat_translation_error_e e = va_arg (*args, nat_translation_error_e);
+
+  switch (e)
+    {
+    case NAT_ED_TRNSL_ERR_SUCCESS:
+      s = format (s, "success");
+      break;
+    case NAT_ED_TRNSL_ERR_TRANSLATION_FAILED:
+      s = format (s, "translation-failed");
+      break;
+    case NAT_ED_TRNSL_ERR_FLOW_MISMATCH:
+      s = format (s, "flow-mismatch");
+      break;
+    }
+  return s;
+}
+
+u8 *
+format_nat_6t_flow (u8 *s, va_list *args)
+{
+  nat_6t_flow_t *f = va_arg (*args, nat_6t_flow_t *);
+
+  s = format (s, "match: %U ", format_nat_6t, &f->match);
+  int r = 0;
+  if (f->ops & NAT_FLOW_OP_SADDR_REWRITE)
+    {
+      s = format (s, "rewrite: saddr %U ", format_ip4_address,
+		  f->rewrite.saddr.as_u8);
+      r = 1;
+    }
+  if (f->ops & NAT_FLOW_OP_SPORT_REWRITE)
+    {
+      if (!r)
+	{
+	  s = format (s, "rewrite: ");
+	  r = 1;
+	}
+      s = format (s, "sport %u ", clib_net_to_host_u16 (f->rewrite.sport));
+    }
+  if (f->ops & NAT_FLOW_OP_DADDR_REWRITE)
+    {
+      if (!r)
+	{
+	  s = format (s, "rewrite: ");
+	  r = 1;
+	}
+      s = format (s, "daddr %U ", format_ip4_address, f->rewrite.daddr.as_u8);
+    }
+  if (f->ops & NAT_FLOW_OP_DPORT_REWRITE)
+    {
+      if (!r)
+	{
+	  s = format (s, "rewrite: ");
+	  r = 1;
+	}
+      s = format (s, "dport %u ", clib_net_to_host_u16 (f->rewrite.dport));
+    }
+  if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE)
+    {
+      if (!r)
+	{
+	  s = format (s, "rewrite: ");
+	  r = 1;
+	}
+      s = format (s, "icmp-id %u ", clib_net_to_host_u16 (f->rewrite.icmp_id));
+    }
+  if (f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
+    {
+      if (!r)
+	{
+	  s = format (s, "rewrite: ");
+	  r = 1;
+	}
+      s = format (s, "txfib %u ", f->rewrite.fib_index);
+    }
+  return s;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */