nat44_ed.c

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/*
 * 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>

#include <vpp/stats/stat_segment.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)

/* 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 ("ip4-sv-reassembly-output-feature"),
  .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
};
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 ("ip4-sv-reassembly-output-feature"),
  .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
};
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)",
};

static void nat44_ed_db_init (u32 translations, u32 translation_buckets);

static void nat44_ed_db_free ();

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 */
  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;
        }
    }

  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;

  #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 _

  if (twice_nat)
    return 0;

  /* Add external address to FIB */
  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;
  }

  return 0;
}

static int
is_snat_address_used_in_static_mapping (snat_main_t * sm, ip4_address_t addr)
{
  snat_static_mapping_t *m;
  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;
  }

  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;
  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;
  }
  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))
            {
              pool_foreach (local, m->locals)
               {
                if (local->vrf_id == vrf_id)
                  return VNET_API_ERROR_VALUE_EXIST;
              }
              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, nat44_ed_get_in2out_worker_index (
                                  0, &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;

          pool_foreach (local, m->locals)
           {
            if (local->vrf_id == vrf_id)
              find = local - m->locals;
          }
          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 */
  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;
  }

  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,
                nat44_ed_get_in2out_worker_index (0, &ip, m->fib_index, 0), 1);
            }
        }

      /* Assign workers */
      if (sm->num_workers > 1)
        {
          clib_bitmap_foreach (i, bitmap)
             {
               vec_add1(m->workers, i);
            }
        }
    }
  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;
        }

      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,
                nat44_ed_get_in2out_worker_index (0, &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);
            }
      }
      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;

  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;
      }
  }

  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,
            nat44_ed_get_in2out_worker_index (0, &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 != 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);
      }

      pool_put (m->locals, match_local);
    }

  vec_free (m->workers);

  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,
          nat44_ed_get_in2out_worker_index (0, &ip, local->fib_index, 0), 1);
      }
  }

  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)
    {
      clib_bitmap_foreach (i, bitmap)  { vec_add1(m->workers, i); }
    }

  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 };
      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);
      }
    }
  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;

  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;
            }
        }
    }
}

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;
    }

  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;
      }
  }

  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)
    {
      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;
            }
        }
      if (!is_del)
        {
          vec_add2 (sm->outside_fibs, outside_fib, 1);
          outside_fib->refcount = 1;
          outside_fib->fib_index = fib_index;
        }
    }

feature_set:
  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;
      }
  }

  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:
  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);
  }

  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;
    }

  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;
      }
  }

  update_per_vrf_sessions_vec (fib_index, is_del);

  if (!is_inside)
    {
      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;
            }
        }
      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);

  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;
      }
  }

  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;

  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);
  }

  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);
  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++;
    }

  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;
    }

  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;
        }
    }

  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->out2in_node_index = node->index;

  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out");
  sm->in2out_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");
  sm->max_cfg_sessions_gauge = stat_segment_new_entry (
    (u8 *) "/nat44-ed/max-cfg-sessions", STAT_DIR_TYPE_SCALAR_INDEX);

#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;
  stat_segment_set_state_counter (sm->max_cfg_sessions_gauge,
                                  sm->max_translations_per_thread);
  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);

  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 (vlib_main_t *vm, 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 (
                               vm, 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 (nat44_ed_get_in2out_worker_index (0, &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;
}

u32
nat44_ed_get_in2out_worker_index (vlib_buffer_t *b, 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;

  u32 fib_index = rx_fib_index;
  if (b)
    {
      if (PREDICT_FALSE (is_output))
        {
          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,
                  } ,
          };

          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:
              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;
                        }
                    }
                }
              break;
            }
        }

      init_ed_k (&kv16, ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
                 ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
                 fib_index, ip->protocol);

      if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16))
        {
          next_worker_index = ed_value_get_thread_index (&value16);
          vnet_buffer2 (b)->nat.cached_session_index =
            ed_value_get_session_index (&value16);
          goto out;
        }

      // dst NAT
      init_ed_k (&kv16, ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
                 ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
                 rx_fib_index, ip->protocol);
      if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16))
        {
          next_worker_index = ed_value_get_thread_index (&value16);
          vnet_buffer2 (b)->nat.cached_dst_nat_session_index =
            ed_value_get_session_index (&value16);
          goto out;
        }
    }

  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)];

out:
  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;
}

u32
nat44_ed_get_out2in_worker_index (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;

  u32 proto, next_worker_index = 0;
  u16 port;
  snat_static_mapping_t *m;
  u32 hash;

  proto = ip_proto_to_nat_proto (ip->protocol);

  if (PREDICT_FALSE (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)))
            {
              next_worker_index = ed_value_get_thread_index (&value16);
              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;
            }
        }
    }

  init_ed_k (&kv16, ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
             ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
             rx_fib_index, ip->protocol);

  if (PREDICT_TRUE (
        !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
    {
      vnet_buffer2 (b)->nat.cached_session_index =
        ed_value_get_session_index (&value16);
      next_worker_index = ed_value_get_thread_index (&value16);
      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;
    }

  port = vnet_buffer (b)->ip.reass.l4_dst_port;

  if (PREDICT_FALSE (ip->protocol == IP_PROTOCOL_ICMP))
    {
      udp_header_t *udp = ip4_next_header (ip);
      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 ();

  stat_segment_set_state_counter (sm->max_cfg_sessions_gauge,
                                  sm->max_translations_per_thread);

  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,
      nat44_ed_get_in2out_worker_index (0, &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;
}

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",
  },
};

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.sport)
    {
      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.sport);
    }
  else
    {
      f->rewrite.icmp_id = f->match.sport;
    }
  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);
  if (0xffff == ip->checksum)
    ip->checksum = 0;
  ASSERT (ip4_header_checksum_is_valid (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:
 */