in2out_ed.c

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/*
 * Copyright (c) 2018 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.
 */
/**
 * @file
 * @brief NAT44 endpoint-dependent inside to outside network translation
 */

#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vnet/ip/ip.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/fib/ip4_fib.h>
#include <vnet/udp/udp.h>
#include <vppinfra/error.h>
#include <nat/nat.h>
#include <nat/nat_ipfix_logging.h>
#include <nat/nat_inlines.h>
#include <nat/nat44_inlines.h>
#include <nat/nat_syslog.h>
#include <nat/nat_ha.h>

static char *nat_in2out_ed_error_strings[] = {
#define _(sym,string) string,
  foreach_nat_in2out_ed_error
#undef _
};

typedef struct
{
  u32 sw_if_index;
  u32 next_index;
  u32 session_index;
  u32 is_slow_path;
} nat_in2out_ed_trace_t;

static u8 *
format_nat_in2out_ed_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  nat_in2out_ed_trace_t *t = va_arg (*args, nat_in2out_ed_trace_t *);
  char *tag;

  tag =
    t->is_slow_path ? "NAT44_IN2OUT_ED_SLOW_PATH" :
    "NAT44_IN2OUT_ED_FAST_PATH";

  s = format (s, "%s: sw_if_index %d, next index %d, session %d", tag,
              t->sw_if_index, t->next_index, t->session_index);

  return s;
}

#ifndef CLIB_MARCH_VARIANT
int
nat44_i2o_ed_is_idle_session_cb (clib_bihash_kv_16_8_t * kv, void *arg)
{
  snat_main_t *sm = &snat_main;
  nat44_is_idle_session_ctx_t *ctx = arg;
  snat_session_t *s;
  u64 sess_timeout_time;
  nat_ed_ses_key_t ed_key;
  clib_bihash_kv_16_8_t ed_kv;
  int i;
  snat_address_t *a;
  snat_session_key_t key;
  snat_main_per_thread_data_t *tsm = vec_elt_at_index (sm->per_thread_data,
                                                       ctx->thread_index);

  s = pool_elt_at_index (tsm->sessions, kv->value);
  sess_timeout_time = s->last_heard + (f64) nat44_session_get_timeout (sm, s);
  if (ctx->now >= sess_timeout_time)
    {
      if (is_fwd_bypass_session (s))
        goto delete;

      ed_key.l_addr = s->out2in.addr;
      ed_key.r_addr = s->ext_host_addr;
      ed_key.fib_index = s->out2in.fib_index;
      if (snat_is_unk_proto_session (s))
        {
          ed_key.proto = s->in2out.port;
          ed_key.r_port = 0;
          ed_key.l_port = 0;
        }
      else
        {
          ed_key.proto = snat_proto_to_ip_proto (s->in2out.protocol);
          ed_key.l_port = s->out2in.port;
          ed_key.r_port = s->ext_host_port;
        }
      ed_kv.key[0] = ed_key.as_u64[0];
      ed_kv.key[1] = ed_key.as_u64[1];
      if (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &ed_kv, 0))
        nat_elog_warn ("out2in_ed key del failed");

      if (snat_is_unk_proto_session (s))
        goto delete;

      snat_ipfix_logging_nat44_ses_delete (ctx->thread_index,
                                           s->in2out.addr.as_u32,
                                           s->out2in.addr.as_u32,
                                           s->in2out.protocol,
                                           s->in2out.port,
                                           s->out2in.port,
                                           s->in2out.fib_index);

      nat_syslog_nat44_sdel (s->user_index, s->in2out.fib_index,
                             &s->in2out.addr, s->in2out.port,
                             &s->ext_host_nat_addr, s->ext_host_nat_port,
                             &s->out2in.addr, s->out2in.port,
                             &s->ext_host_addr, s->ext_host_port,
                             s->in2out.protocol, is_twice_nat_session (s));

      nat_ha_sdel (&s->out2in.addr, s->out2in.port, &s->ext_host_addr,
                   s->ext_host_port, s->out2in.protocol, s->out2in.fib_index,
                   ctx->thread_index);

      if (is_twice_nat_session (s))
        {
          for (i = 0; i < vec_len (sm->twice_nat_addresses); i++)
            {
              key.protocol = s->in2out.protocol;
              key.port = s->ext_host_nat_port;
              a = sm->twice_nat_addresses + i;
              if (a->addr.as_u32 == s->ext_host_nat_addr.as_u32)
                {
                  snat_free_outside_address_and_port (sm->twice_nat_addresses,
                                                      ctx->thread_index,
                                                      &key);
                  break;
                }
            }
        }

      if (snat_is_session_static (s))
        goto delete;

      snat_free_outside_address_and_port (sm->addresses, ctx->thread_index,
                                          &s->out2in);
    delete:
      nat44_delete_session (sm, s, ctx->thread_index);
      return 1;
    }

  return 0;
}
#endif

static inline u32
icmp_in2out_ed_slow_path (snat_main_t * sm, vlib_buffer_t * b0,
                          ip4_header_t * ip0, icmp46_header_t * icmp0,
                          u32 sw_if_index0, u32 rx_fib_index0,
                          vlib_node_runtime_t * node, u32 next0, f64 now,
                          u32 thread_index, snat_session_t ** p_s0)
{
  next0 = icmp_in2out (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
                       next0, thread_index, p_s0, 0);
  snat_session_t *s0 = *p_s0;
  if (PREDICT_TRUE (next0 != NAT_NEXT_DROP && s0))
    {
      /* Accounting */
      nat44_session_update_counters (s0, now,
                                     vlib_buffer_length_in_chain
                                     (sm->vlib_main, b0), thread_index);
      /* Per-user LRU list maintenance */
      nat44_session_update_lru (sm, s0, thread_index);
    }
  return next0;
}

static u32
slow_path_ed (snat_main_t * sm,
              vlib_buffer_t * b,
              u32 rx_fib_index,
              clib_bihash_kv_16_8_t * kv,
              snat_session_t ** sessionp,
              vlib_node_runtime_t * node, u32 next, u32 thread_index, f64 now)
{
  snat_session_t *s = 0;
  snat_user_t *u;
  snat_session_key_t key0, key1;
  lb_nat_type_t lb = 0, is_sm = 0;
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
  nat_ed_ses_key_t *key = (nat_ed_ses_key_t *) kv->key;
  u32 proto = ip_proto_to_snat_proto (key->proto);
  nat_outside_fib_t *outside_fib;
  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
  u8 identity_nat;
  fib_prefix_t pfx = {
    .fp_proto = FIB_PROTOCOL_IP4,
    .fp_len = 32,
    .fp_addr = {
                .ip4.as_u32 = key->r_addr.as_u32,
                },
  };
  nat44_is_idle_session_ctx_t ctx;

  nat44_session_try_cleanup (&key->l_addr, rx_fib_index, thread_index, now);

  if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
    {
      b->error = node->errors[NAT_IN2OUT_ED_ERROR_MAX_SESSIONS_EXCEEDED];
      nat_ipfix_logging_max_sessions (thread_index, sm->max_translations);
      nat_elog_notice ("maximum sessions exceeded");
      return NAT_NEXT_DROP;
    }

  key0.addr = key->l_addr;
  key0.port = key->l_port;
  key1.protocol = key0.protocol = proto;
  key0.fib_index = rx_fib_index;
  key1.fib_index = sm->outside_fib_index;
  /* First try to match static mapping by local address and port */
  if (snat_static_mapping_match
      (sm, key0, &key1, 0, 0, 0, &lb, 0, &identity_nat))
    {
      /* Try to create dynamic translation */
      if (snat_alloc_outside_address_and_port (sm->addresses, rx_fib_index,
                                               thread_index, &key1,
                                               sm->port_per_thread,
                                               tsm->snat_thread_index))
        {
          nat_elog_notice ("addresses exhausted");
          b->error = node->errors[NAT_IN2OUT_ED_ERROR_OUT_OF_PORTS];
          return NAT_NEXT_DROP;
        }
    }
  else
    {
      if (PREDICT_FALSE (identity_nat))
        {
          *sessionp = s;
          return next;
        }

      is_sm = 1;
    }

  if (proto == SNAT_PROTOCOL_TCP)
    {
      if (!tcp_flags_is_init
          (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags))
        {
          b->error = node->errors[NAT_IN2OUT_ED_ERROR_NON_SYN];
          return NAT_NEXT_DROP;
        }
    }

  u = nat_user_get_or_create (sm, &key->l_addr, rx_fib_index, thread_index);
  if (!u)
    {
      nat_elog_warn ("create NAT user failed");
      if (!is_sm)
        snat_free_outside_address_and_port (sm->addresses,
                                            thread_index, &key1);
      return NAT_NEXT_DROP;
    }

  s = nat_ed_session_alloc (sm, u, thread_index, now);
  if (!s)
    {
      nat44_delete_user_with_no_session (sm, u, thread_index);
      nat_elog_warn ("create NAT session failed");
      if (!is_sm)
        snat_free_outside_address_and_port (sm->addresses,
                                            thread_index, &key1);
      return NAT_NEXT_DROP;
    }

  user_session_increment (sm, u, is_sm);
  if (is_sm)
    s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
  if (lb)
    s->flags |= SNAT_SESSION_FLAG_LOAD_BALANCING;
  s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
  s->ext_host_addr = key->r_addr;
  s->ext_host_port = key->r_port;
  s->in2out = key0;
  s->out2in = key1;
  s->out2in.protocol = key0.protocol;

  switch (vec_len (sm->outside_fibs))
    {
    case 0:
      s->out2in.fib_index = sm->outside_fib_index;
      break;
    case 1:
      s->out2in.fib_index = sm->outside_fibs[0].fib_index;
      break;
    default:
      /* *INDENT-OFF* */
      vec_foreach (outside_fib, sm->outside_fibs)
       {
          fei = fib_table_lookup (outside_fib->fib_index, &pfx);
          if (FIB_NODE_INDEX_INVALID != fei)
            {
              if (fib_entry_get_resolving_interface (fei) != ~0)
                {
                  s->out2in.fib_index = outside_fib->fib_index;
                  break;
                }
            }
        }
      /* *INDENT-ON* */
      break;
    }

  /* Add to lookup tables */
  kv->value = s - tsm->sessions;
  ctx.now = now;
  ctx.thread_index = thread_index;
  if (clib_bihash_add_or_overwrite_stale_16_8 (&tsm->in2out_ed, kv,
                                               nat44_i2o_ed_is_idle_session_cb,
                                               &ctx))
    nat_elog_notice ("in2out-ed key add failed");

  make_ed_kv (kv, &key1.addr, &key->r_addr, key->proto, s->out2in.fib_index,
              key1.port, key->r_port);
  kv->value = s - tsm->sessions;
  if (clib_bihash_add_or_overwrite_stale_16_8 (&tsm->out2in_ed, kv,
                                               nat44_o2i_ed_is_idle_session_cb,
                                               &ctx))
    nat_elog_notice ("out2in-ed key add failed");

  *sessionp = s;

  /* log NAT event */
  snat_ipfix_logging_nat44_ses_create (thread_index,
                                       s->in2out.addr.as_u32,
                                       s->out2in.addr.as_u32,
                                       s->in2out.protocol,
                                       s->in2out.port,
                                       s->out2in.port, s->in2out.fib_index);

  nat_syslog_nat44_sadd (s->user_index, s->in2out.fib_index,
                         &s->in2out.addr, s->in2out.port,
                         &s->ext_host_nat_addr, s->ext_host_nat_port,
                         &s->out2in.addr, s->out2in.port,
                         &s->ext_host_addr, s->ext_host_port,
                         s->in2out.protocol, 0);

  nat_ha_sadd (&s->in2out.addr, s->in2out.port, &s->out2in.addr,
               s->out2in.port, &s->ext_host_addr, s->ext_host_port,
               &s->ext_host_nat_addr, s->ext_host_nat_port,
               s->in2out.protocol, s->in2out.fib_index, s->flags,
               thread_index, 0);

  return next;
}

static_always_inline int
nat44_ed_not_translate (snat_main_t * sm, vlib_node_runtime_t * node,
                        u32 sw_if_index, ip4_header_t * ip, u32 proto,
                        u32 rx_fib_index, u32 thread_index)
{
  udp_header_t *udp = ip4_next_header (ip);
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
  clib_bihash_kv_16_8_t kv, value;
  snat_session_key_t key0, key1;

  make_ed_kv (&kv, &ip->dst_address, &ip->src_address, ip->protocol,
              sm->outside_fib_index, udp->dst_port, udp->src_port);

  /* NAT packet aimed at external address if */
  /* has active sessions */
  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv, &value))
    {
      key0.addr = ip->dst_address;
      key0.port = udp->dst_port;
      key0.protocol = proto;
      key0.fib_index = sm->outside_fib_index;
      /* or is static mappings */
      if (!snat_static_mapping_match (sm, key0, &key1, 1, 0, 0, 0, 0, 0))
        return 0;
    }
  else
    return 0;

  if (sm->forwarding_enabled)
    return 1;

  return snat_not_translate_fast (sm, node, sw_if_index, ip, proto,
                                  rx_fib_index);
}

static_always_inline int
nat_not_translate_output_feature_fwd (snat_main_t * sm, ip4_header_t * ip,
                                      u32 thread_index, f64 now,
                                      vlib_main_t * vm, vlib_buffer_t * b)
{
  nat_ed_ses_key_t key;
  clib_bihash_kv_16_8_t kv, value;
  snat_session_t *s = 0;
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];

  if (!sm->forwarding_enabled)
    return 0;

  if (ip->protocol == IP_PROTOCOL_ICMP)
    {
      key.as_u64[0] = key.as_u64[1] = 0;
      if (get_icmp_i2o_ed_key (b, ip, &key))
        return 0;
      key.fib_index = 0;
      kv.key[0] = key.as_u64[0];
      kv.key[1] = key.as_u64[1];
    }
  else if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
    {
      make_ed_kv (&kv, &ip->src_address, &ip->dst_address, ip->protocol, 0,
                  vnet_buffer (b)->ip.reass.l4_src_port,
                  vnet_buffer (b)->ip.reass.l4_dst_port);
    }
  else
    {
      make_ed_kv (&kv, &ip->src_address, &ip->dst_address, ip->protocol, 0, 0,
                  0);
    }

  if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &kv, &value))
    {
      s = pool_elt_at_index (tsm->sessions, value.value);
      if (is_fwd_bypass_session (s))
        {
          if (ip->protocol == IP_PROTOCOL_TCP)
            {
              if (nat44_set_tcp_session_state_i2o (sm, s, b, thread_index))
                return 1;
            }
          /* Accounting */
          nat44_session_update_counters (s, now,
                                         vlib_buffer_length_in_chain (vm, b),
                                         thread_index);
          /* Per-user LRU list maintenance */
          nat44_session_update_lru (sm, s, thread_index);
          return 1;
        }
      else
        return 0;
    }

  return 0;
}

static_always_inline int
nat44_ed_not_translate_output_feature (snat_main_t * sm, ip4_header_t * ip,
                                       u8 proto, u16 src_port, u16 dst_port,
                                       u32 thread_index, u32 rx_sw_if_index,
                                       u32 tx_sw_if_index)
{
  clib_bihash_kv_16_8_t kv, value;
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
  snat_interface_t *i;
  snat_session_t *s;
  u32 rx_fib_index = ip4_fib_table_get_index_for_sw_if_index (rx_sw_if_index);
  u32 tx_fib_index = ip4_fib_table_get_index_for_sw_if_index (tx_sw_if_index);

  /* src NAT check */
  make_ed_kv (&kv, &ip->src_address, &ip->dst_address, proto, tx_fib_index,
              src_port, dst_port);
  if (!clib_bihash_search_16_8 (&tsm->out2in_ed, &kv, &value))
    {
      s = pool_elt_at_index (tsm->sessions, value.value);
      if (nat44_is_ses_closed (s))
        {
          nat_free_session_data (sm, s, thread_index, 0);
          nat44_delete_session (sm, s, thread_index);
        }
      else
        s->flags |= SNAT_SESSION_FLAG_OUTPUT_FEATURE;
      return 1;
    }

  /* dst NAT check */
  make_ed_kv (&kv, &ip->dst_address, &ip->src_address, proto, rx_fib_index,
              dst_port, src_port);
  if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &kv, &value))
    {
      s = pool_elt_at_index (tsm->sessions, value.value);
      if (is_fwd_bypass_session (s))
        return 0;

      /* hairpinning */
      /* *INDENT-OFF* */
      pool_foreach (i, sm->output_feature_interfaces,
      ({
        if ((nat_interface_is_inside (i)) && (rx_sw_if_index == i->sw_if_index))
           return 0;
      }));
      /* *INDENT-ON* */
      return 1;
    }

  return 0;
}

#ifndef CLIB_MARCH_VARIANT
u32
icmp_match_in2out_ed (snat_main_t * sm, vlib_node_runtime_t * node,
                      u32 thread_index, vlib_buffer_t * b, ip4_header_t * ip,
                      u8 * p_proto, snat_session_key_t * p_value,
                      u8 * p_dont_translate, void *d, void *e)
{
  u32 sw_if_index;
  u32 rx_fib_index;
  nat_ed_ses_key_t key;
  snat_session_t *s = 0;
  u8 dont_translate = 0;
  clib_bihash_kv_16_8_t kv, value;
  u32 next = ~0;
  int err;
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];

  sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
  rx_fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);

  key.as_u64[0] = key.as_u64[1] = 0;
  err = get_icmp_i2o_ed_key (b, ip, &key);
  if (err != 0)
    {
      b->error = node->errors[err];
      next = NAT_NEXT_DROP;
      goto out;
    }
  key.fib_index = rx_fib_index;

  kv.key[0] = key.as_u64[0];
  kv.key[1] = key.as_u64[1];

  if (clib_bihash_search_16_8 (&tsm->in2out_ed, &kv, &value))
    {
      if (vnet_buffer (b)->sw_if_index[VLIB_TX] != ~0)
        {
          if (PREDICT_FALSE
              (nat44_ed_not_translate_output_feature
               (sm, ip, key.proto, key.l_port, key.r_port, thread_index,
                sw_if_index, vnet_buffer (b)->sw_if_index[VLIB_TX])))
            {
              dont_translate = 1;
              goto out;
            }
        }
      else
        {
          if (PREDICT_FALSE (nat44_ed_not_translate (sm, node, sw_if_index,
                                                     ip, SNAT_PROTOCOL_ICMP,
                                                     rx_fib_index,
                                                     thread_index)))
            {
              dont_translate = 1;
              goto out;
            }
        }

      if (PREDICT_FALSE
          (icmp_type_is_error_message
           (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags)))
        {
          b->error = node->errors[NAT_IN2OUT_ED_ERROR_BAD_ICMP_TYPE];
          next = NAT_NEXT_DROP;
          goto out;
        }

      next = slow_path_ed (sm, b, rx_fib_index, &kv, &s, node, next,
                           thread_index, vlib_time_now (sm->vlib_main));

      if (PREDICT_FALSE (next == NAT_NEXT_DROP))
        goto out;

      if (!s)
        {
          dont_translate = 1;
          goto out;
        }
    }
  else
    {
      if (PREDICT_FALSE
          (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
           ICMP4_echo_request
           && vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
           ICMP4_echo_reply
           && !icmp_type_is_error_message (vnet_buffer (b)->ip.
                                           reass.icmp_type_or_tcp_flags)))
        {
          b->error = node->errors[NAT_IN2OUT_ED_ERROR_BAD_ICMP_TYPE];
          next = NAT_NEXT_DROP;
          goto out;
        }

      s = pool_elt_at_index (tsm->sessions, value.value);
    }

  *p_proto = ip_proto_to_snat_proto (key.proto);
out:
  if (s)
    *p_value = s->out2in;
  *p_dont_translate = dont_translate;
  if (d)
    *(snat_session_t **) d = s;
  return next;
}
#endif

static snat_session_t *
nat44_ed_in2out_unknown_proto (snat_main_t * sm,
                               vlib_buffer_t * b,
                               ip4_header_t * ip,
                               u32 rx_fib_index,
                               u32 thread_index,
                               f64 now,
                               vlib_main_t * vm, vlib_node_runtime_t * node)
{
  clib_bihash_kv_8_8_t kv, value;
  clib_bihash_kv_16_8_t s_kv, s_value;
  snat_static_mapping_t *m;
  u32 old_addr, new_addr = 0;
  ip_csum_t sum;
  snat_user_t *u;
  dlist_elt_t *head, *elt;
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
  u32 elt_index, head_index, ses_index;
  snat_session_t *s;
  u32 outside_fib_index = sm->outside_fib_index;
  int i;
  u8 is_sm = 0;
  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:
      outside_fib_index = sm->outside_fib_index;
      break;
    case 1:
      outside_fib_index = sm->outside_fibs[0].fib_index;
      break;
    default:
      /* *INDENT-OFF* */
      vec_foreach (outside_fib, sm->outside_fibs)
        {
          fei = fib_table_lookup (outside_fib->fib_index, &pfx);
          if (FIB_NODE_INDEX_INVALID != fei)
            {
              if (fib_entry_get_resolving_interface (fei) != ~0)
                {
                  outside_fib_index = outside_fib->fib_index;
                  break;
                }
            }
        }
      /* *INDENT-ON* */
      break;
    }
  old_addr = ip->src_address.as_u32;

  make_ed_kv (&s_kv, &ip->src_address, &ip->dst_address, ip->protocol,
              rx_fib_index, 0, 0);

  if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &s_kv, &s_value))
    {
      s = pool_elt_at_index (tsm->sessions, s_value.value);
      new_addr = ip->src_address.as_u32 = s->out2in.addr.as_u32;
    }
  else
    {
      if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
        {
          b->error = node->errors[NAT_IN2OUT_ED_ERROR_MAX_SESSIONS_EXCEEDED];
          nat_ipfix_logging_max_sessions (thread_index, sm->max_translations);
          nat_elog_notice ("maximum sessions exceeded");
          return 0;
        }

      u = nat_user_get_or_create (sm, &ip->src_address, rx_fib_index,
                                  thread_index);
      if (!u)
        {
          nat_elog_warn ("create NAT user failed");
          return 0;
        }

      make_sm_kv (&kv, &ip->src_address, 0, rx_fib_index, 0);

      /* Try to find static mapping first */
      if (!clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv, &value))
        {
          m = pool_elt_at_index (sm->static_mappings, value.value);
          new_addr = ip->src_address.as_u32 = m->external_addr.as_u32;
          is_sm = 1;
          goto create_ses;
        }
      /* Fallback to 3-tuple key */
      else
        {
          /* Choose same out address as for TCP/UDP session to same destination */
          head_index = u->sessions_per_user_list_head_index;
          head = pool_elt_at_index (tsm->list_pool, head_index);
          elt_index = head->next;
          if (PREDICT_FALSE (elt_index == ~0))
            ses_index = ~0;
          else
            {
              elt = pool_elt_at_index (tsm->list_pool, elt_index);
              ses_index = elt->value;
            }

          while (ses_index != ~0)
            {
              s = pool_elt_at_index (tsm->sessions, ses_index);
              elt_index = elt->next;
              elt = pool_elt_at_index (tsm->list_pool, elt_index);
              ses_index = elt->value;

              if (s->ext_host_addr.as_u32 == ip->dst_address.as_u32)
                {
                  new_addr = ip->src_address.as_u32 = s->out2in.addr.as_u32;

                  make_ed_kv (&s_kv, &s->out2in.addr, &ip->dst_address,
                              ip->protocol, outside_fib_index, 0, 0);
                  if (clib_bihash_search_16_8
                      (&tsm->out2in_ed, &s_kv, &s_value))
                    goto create_ses;

                  break;
                }
            }

          for (i = 0; i < vec_len (sm->addresses); i++)
            {
              make_ed_kv (&s_kv, &sm->addresses[i].addr, &ip->dst_address,
                          ip->protocol, outside_fib_index, 0, 0);
              if (clib_bihash_search_16_8 (&tsm->out2in_ed, &s_kv, &s_value))
                {
                  new_addr = ip->src_address.as_u32 =
                    sm->addresses[i].addr.as_u32;
                  goto create_ses;
                }
            }
          return 0;
        }

    create_ses:
      s = nat_ed_session_alloc (sm, u, thread_index, now);
      if (!s)
        {
          nat44_delete_user_with_no_session (sm, u, thread_index);
          nat_elog_warn ("create NAT session failed");
          return 0;
        }

      s->ext_host_addr.as_u32 = ip->dst_address.as_u32;
      s->flags |= SNAT_SESSION_FLAG_UNKNOWN_PROTO;
      s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
      s->out2in.addr.as_u32 = new_addr;
      s->out2in.fib_index = outside_fib_index;
      s->in2out.addr.as_u32 = old_addr;
      s->in2out.fib_index = rx_fib_index;
      s->in2out.port = s->out2in.port = ip->protocol;
      if (is_sm)
        s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
      user_session_increment (sm, u, is_sm);

      /* Add to lookup tables */
      make_ed_kv (&s_kv, &s->in2out.addr, &ip->dst_address, ip->protocol,
                  rx_fib_index, 0, 0);
      s_kv.value = s - tsm->sessions;
      if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &s_kv, 1))
        nat_elog_notice ("in2out key add failed");

      make_ed_kv (&s_kv, &s->out2in.addr, &ip->dst_address, ip->protocol,
                  outside_fib_index, 0, 0);
      s_kv.value = s - tsm->sessions;
      if (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &s_kv, 1))
        nat_elog_notice ("out2in key add failed");
    }

  /* Update IP checksum */
  sum = ip->checksum;
  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, src_address);
  ip->checksum = ip_csum_fold (sum);

  /* Accounting */
  nat44_session_update_counters (s, now, vlib_buffer_length_in_chain (vm, b),
                                 thread_index);
  /* Per-user LRU list maintenance */
  nat44_session_update_lru (sm, s, thread_index);

  /* Hairpinning */
  if (vnet_buffer (b)->sw_if_index[VLIB_TX] == ~0)
    nat44_ed_hairpinning_unknown_proto (sm, b, ip);

  if (vnet_buffer (b)->sw_if_index[VLIB_TX] == ~0)
    vnet_buffer (b)->sw_if_index[VLIB_TX] = outside_fib_index;

  return s;
}

static inline uword
nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
                                vlib_node_runtime_t * node,
                                vlib_frame_t * frame, int is_slow_path,
                                int is_output_feature)
{
  u32 n_left_from, *from, *to_next, pkts_processed = 0, stats_node_index;
  nat_next_t next_index;
  snat_main_t *sm = &snat_main;
  f64 now = vlib_time_now (vm);
  u32 thread_index = vm->thread_index;
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
  u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
    0, def_slow;

  def_slow = is_output_feature ? NAT_NEXT_IN2OUT_ED_OUTPUT_SLOW_PATH :
    NAT_NEXT_IN2OUT_ED_SLOW_PATH;

  stats_node_index = is_slow_path ? sm->ed_in2out_slowpath_node_index :
    sm->ed_in2out_node_index;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from >= 4 && n_left_to_next >= 2)
        {
          u32 bi0, bi1;
          vlib_buffer_t *b0, *b1;
          u32 next0, sw_if_index0, rx_fib_index0, iph_offset0 = 0, proto0,
            new_addr0, old_addr0;
          u32 next1, sw_if_index1, rx_fib_index1, iph_offset1 = 0, proto1,
            new_addr1, old_addr1;
          u16 old_port0, new_port0, old_port1, new_port1;
          ip4_header_t *ip0, *ip1;
          udp_header_t *udp0, *udp1;
          tcp_header_t *tcp0, *tcp1;
          icmp46_header_t *icmp0, *icmp1;
          snat_session_t *s0 = 0, *s1 = 0;
          clib_bihash_kv_16_8_t kv0, value0, kv1, value1;
          ip_csum_t sum0, sum1;

          /* Prefetch next iteration. */
          {
            vlib_buffer_t *p2, *p3;

            p2 = vlib_get_buffer (vm, from[2]);
            p3 = vlib_get_buffer (vm, from[3]);

            vlib_prefetch_buffer_header (p2, LOAD);
            vlib_prefetch_buffer_header (p3, LOAD);

            CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
            CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
          }

          /* speculatively enqueue b0 and b1 to the current next frame */
          to_next[0] = bi0 = from[0];
          to_next[1] = bi1 = from[1];
          from += 2;
          to_next += 2;
          n_left_from -= 2;
          n_left_to_next -= 2;

          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);

          if (is_output_feature)
            {
              // output feature fast path is enabled on the arc
              // we need new arc_next feature
              if (PREDICT_TRUE (!is_slow_path))
                {
                  vnet_feature_next (&nat_buffer_opaque (b0)->arc_next, b0);
                  vnet_feature_next (&nat_buffer_opaque (b1)->arc_next, b1);
                }

              iph_offset0 = vnet_buffer (b0)->ip.reass.save_rewrite_length;
              iph_offset1 = vnet_buffer (b1)->ip.reass.save_rewrite_length;
            }

          next0 = nat_buffer_opaque (b0)->arc_next;
          next1 = nat_buffer_opaque (b1)->arc_next;

          ip0 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0) +
                                  iph_offset0);

          sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
          rx_fib_index0 =
            fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
                                                 sw_if_index0);

          if (PREDICT_FALSE (ip0->ttl == 1))
            {
              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
                                           0);
              next0 = NAT_NEXT_ICMP_ERROR;
              goto trace00;
            }

          udp0 = ip4_next_header (ip0);
          tcp0 = (tcp_header_t *) udp0;
          icmp0 = (icmp46_header_t *) udp0;
          proto0 = ip_proto_to_snat_proto (ip0->protocol);

          if (is_slow_path)
            {
              if (PREDICT_FALSE (proto0 == ~0))
                {
                  s0 = nat44_ed_in2out_unknown_proto (sm, b0, ip0,
                                                      rx_fib_index0,
                                                      thread_index, now, vm,
                                                      node);
                  if (!s0)
                    next0 = NAT_NEXT_DROP;
                  other_packets++;
                  goto trace00;
                }

              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                {
                  next0 = icmp_in2out_ed_slow_path
                    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
                     next0, now, thread_index, &s0);
                  icmp_packets++;
                  goto trace00;
                }
            }
          else
            {
              if (PREDICT_FALSE (proto0 == ~0))
                {
                  next0 = def_slow;
                  goto trace00;
                }

              if (is_output_feature)
                {
                  if (PREDICT_FALSE
                      (nat_not_translate_output_feature_fwd
                       (sm, ip0, thread_index, now, vm, b0)))
                    goto trace00;
                }

              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                {
                  next0 = def_slow;
                  goto trace00;
                }
            }

          make_ed_kv (&kv0, &ip0->src_address, &ip0->dst_address,
                      ip0->protocol, rx_fib_index0,
                      vnet_buffer (b0)->ip.reass.l4_src_port,
                      vnet_buffer (b0)->ip.reass.l4_dst_port);

          if (clib_bihash_search_16_8 (&tsm->in2out_ed, &kv0, &value0))
            {
              if (is_slow_path)
                {
                  if (is_output_feature)
                    {
                      if (PREDICT_FALSE
                          (nat44_ed_not_translate_output_feature
                           (sm, ip0, ip0->protocol,
                            vnet_buffer (b0)->ip.reass.l4_src_port,
                            vnet_buffer (b0)->ip.reass.l4_dst_port,
                            thread_index, sw_if_index0,
                            vnet_buffer (b0)->sw_if_index[VLIB_TX])))
                        goto trace00;

                      /*
                       * Send DHCP packets to the ipv4 stack, or we won't
                       * be able to use dhcp client on the outside interface
                       */
                      if (PREDICT_FALSE
                          ((b0->flags & VNET_BUFFER_F_LOCALLY_ORIGINATED)
                           && proto0 == SNAT_PROTOCOL_UDP
                           && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
                               clib_host_to_net_u16
                               (UDP_DST_PORT_dhcp_to_server))))
                        goto trace00;
                    }
                  else
                    {
                      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node,
                                                                 sw_if_index0,
                                                                 ip0, proto0,
                                                                 rx_fib_index0,
                                                                 thread_index)))
                        goto trace00;
                    }

                  next0 =
                    slow_path_ed (sm, b0, rx_fib_index0, &kv0, &s0, node,
                                  next0, thread_index, now);

                  if (PREDICT_FALSE (next0 == NAT_NEXT_DROP))
                    goto trace00;

                  if (PREDICT_FALSE (!s0))
                    goto trace00;
                }
              else
                {
                  next0 = def_slow;
                  goto trace00;
                }
            }
          else
            {
              s0 = pool_elt_at_index (tsm->sessions, value0.value);
            }

          b0->flags |= VNET_BUFFER_F_IS_NATED;

          if (!is_output_feature)
            vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index;

          old_addr0 = ip0->src_address.as_u32;
          new_addr0 = ip0->src_address.as_u32 = s0->out2in.addr.as_u32;
          sum0 = ip0->checksum;
          sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                 src_address);
          if (PREDICT_FALSE (is_twice_nat_session (s0)))
            sum0 = ip_csum_update (sum0, ip0->dst_address.as_u32,
                                   s0->ext_host_addr.as_u32, ip4_header_t,
                                   dst_address);
          ip0->checksum = ip_csum_fold (sum0);

          old_port0 = vnet_buffer (b0)->ip.reass.l4_src_port;

          if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
            {
              if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
                {
                  new_port0 = udp0->src_port = s0->out2in.port;
                  sum0 = tcp0->checksum;
                  sum0 =
                    ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                    dst_address);
                  sum0 =
                    ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
                                    length);
                  if (PREDICT_FALSE (is_twice_nat_session (s0)))
                    {
                      sum0 = ip_csum_update (sum0, ip0->dst_address.as_u32,
                                             s0->ext_host_addr.as_u32,
                                             ip4_header_t, dst_address);
                      sum0 =
                        ip_csum_update (sum0,
                                        vnet_buffer (b0)->ip.
                                        reass.l4_dst_port, s0->ext_host_port,
                                        ip4_header_t, length);
                      tcp0->dst_port = s0->ext_host_port;
                      ip0->dst_address.as_u32 = s0->ext_host_addr.as_u32;
                    }
                  mss_clamping (sm, tcp0, &sum0);
                  tcp0->checksum = ip_csum_fold (sum0);
                }
              tcp_packets++;
              if (nat44_set_tcp_session_state_i2o (sm, s0, b0, thread_index))
                goto trace00;
            }
          else if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment
                   && udp0->checksum)
            {
              new_port0 = udp0->src_port = s0->out2in.port;
              sum0 = udp0->checksum;
              sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                     dst_address);
              sum0 = ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
                                     length);
              if (PREDICT_FALSE (is_twice_nat_session (s0)))
                {
                  sum0 = ip_csum_update (sum0, ip0->dst_address.as_u32,
                                         s0->ext_host_addr.as_u32,
                                         ip4_header_t, dst_address);
                  sum0 =
                    ip_csum_update (sum0,
                                    vnet_buffer (b0)->ip.reass.l4_dst_port,
                                    s0->ext_host_port, ip4_header_t, length);
                  udp0->dst_port = s0->ext_host_port;
                  ip0->dst_address.as_u32 = s0->ext_host_addr.as_u32;
                }
              udp0->checksum = ip_csum_fold (sum0);
              udp_packets++;
            }
          else
            {
              if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
                {
                  new_port0 = udp0->src_port = s0->out2in.port;
                  if (PREDICT_FALSE (is_twice_nat_session (s0)))
                    {
                      udp0->dst_port = s0->ext_host_port;
                      ip0->dst_address.as_u32 = s0->ext_host_addr.as_u32;
                    }
                  udp_packets++;
                }
            }

          /* Accounting */
          nat44_session_update_counters (s0, now,
                                         vlib_buffer_length_in_chain (vm,
                                                                      b0),
                                         thread_index);
          /* Per-user LRU list maintenance */
          nat44_session_update_lru (sm, s0, thread_index);

        trace00:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat_in2out_ed_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->is_slow_path = is_slow_path;
              t->sw_if_index = sw_if_index0;
              t->next_index = next0;
              t->session_index = ~0;
              if (s0)
                t->session_index = s0 - tsm->sessions;
            }

          pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;

          ip1 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b1) +
                                  iph_offset1);

          sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
          rx_fib_index1 =
            fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
                                                 sw_if_index1);

          if (PREDICT_FALSE (ip1->ttl == 1))
            {
              vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
              icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
                                           0);
              next1 = NAT_NEXT_ICMP_ERROR;
              goto trace01;
            }

          udp1 = ip4_next_header (ip1);
          tcp1 = (tcp_header_t *) udp1;
          icmp1 = (icmp46_header_t *) udp1;
          proto1 = ip_proto_to_snat_proto (ip1->protocol);

          if (is_slow_path)
            {
              if (PREDICT_FALSE (proto1 == ~0))
                {
                  s1 = nat44_ed_in2out_unknown_proto (sm, b1, ip1,
                                                      rx_fib_index1,
                                                      thread_index, now,
                                                      vm, node);
                  if (!s1)
                    next1 = NAT_NEXT_DROP;
                  other_packets++;
                  goto trace01;
                }

              if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
                {
                  next1 = icmp_in2out_ed_slow_path
                    (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1,
                     node, next1, now, thread_index, &s1);
                  icmp_packets++;
                  goto trace01;
                }
            }
          else
            {
              if (PREDICT_FALSE (proto1 == ~0))
                {
                  next1 = def_slow;
                  goto trace01;
                }

              if (is_output_feature)
                {
                  if (PREDICT_FALSE
                      (nat_not_translate_output_feature_fwd
                       (sm, ip1, thread_index, now, vm, b1)))
                    goto trace01;
                }

              if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
                {
                  next1 = def_slow;
                  goto trace01;
                }
            }

          make_ed_kv (&kv1, &ip1->src_address, &ip1->dst_address,
                      ip1->protocol, rx_fib_index1,
                      vnet_buffer (b1)->ip.reass.l4_src_port,
                      vnet_buffer (b1)->ip.reass.l4_dst_port);

          if (clib_bihash_search_16_8 (&tsm->in2out_ed, &kv1, &value1))
            {
              if (is_slow_path)
                {
                  if (is_output_feature)
                    {
                      if (PREDICT_FALSE
                          (nat44_ed_not_translate_output_feature
                           (sm, ip1, ip1->protocol,
                            vnet_buffer (b1)->ip.reass.l4_src_port,
                            vnet_buffer (b1)->ip.reass.l4_dst_port,
                            thread_index, sw_if_index1,
                            vnet_buffer (b1)->sw_if_index[VLIB_TX])))
                        goto trace01;

                      /*
                       * Send DHCP packets to the ipv4 stack, or we won't
                       * be able to use dhcp client on the outside interface
                       */
                      if (PREDICT_FALSE
                          ((b1->flags & VNET_BUFFER_F_LOCALLY_ORIGINATED)
                           && proto1 == SNAT_PROTOCOL_UDP
                           && (vnet_buffer (b1)->ip.reass.l4_dst_port ==
                               clib_host_to_net_u16
                               (UDP_DST_PORT_dhcp_to_server))))
                        goto trace01;
                    }
                  else
                    {
                      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node,
                                                                 sw_if_index1,
                                                                 ip1,
                                                                 proto1,
                                                                 rx_fib_index1,
                                                                 thread_index)))
                        goto trace01;
                    }

                  next1 =
                    slow_path_ed (sm, b1, rx_fib_index1, &kv1, &s1, node,
                                  next1, thread_index, now);

                  if (PREDICT_FALSE (next1 == NAT_NEXT_DROP))
                    goto trace01;

                  if (PREDICT_FALSE (!s1))
                    goto trace01;
                }
              else
                {
                  next1 = def_slow;
                  goto trace01;
                }
            }
          else
            {
              s1 = pool_elt_at_index (tsm->sessions, value1.value);
            }

          b1->flags |= VNET_BUFFER_F_IS_NATED;

          if (!is_output_feature)
            vnet_buffer (b1)->sw_if_index[VLIB_TX] = s1->out2in.fib_index;

          old_addr1 = ip1->src_address.as_u32;
          new_addr1 = ip1->src_address.as_u32 = s1->out2in.addr.as_u32;
          sum1 = ip1->checksum;
          sum1 = ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
                                 src_address);
          if (PREDICT_FALSE (is_twice_nat_session (s1)))
            sum1 = ip_csum_update (sum1, ip1->dst_address.as_u32,
                                   s1->ext_host_addr.as_u32, ip4_header_t,
                                   dst_address);
          ip1->checksum = ip_csum_fold (sum1);

          old_port1 = vnet_buffer (b1)->ip.reass.l4_src_port;

          if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
            {
              if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
                {
                  new_port1 = udp1->src_port = s1->out2in.port;
                  sum1 = tcp1->checksum;
                  sum1 =
                    ip_csum_update (sum1, old_addr1, new_addr1,
                                    ip4_header_t, dst_address);
                  sum1 =
                    ip_csum_update (sum1, old_port1, new_port1,
                                    ip4_header_t, length);
                  if (PREDICT_FALSE (is_twice_nat_session (s1)))
                    {
                      sum1 =
                        ip_csum_update (sum1, ip1->dst_address.as_u32,
                                        s1->ext_host_addr.as_u32,
                                        ip4_header_t, dst_address);
                      sum1 =
                        ip_csum_update (sum1,
                                        vnet_buffer (b1)->ip.
                                        reass.l4_dst_port, s1->ext_host_port,
                                        ip4_header_t, length);
                      tcp1->dst_port = s1->ext_host_port;
                      ip1->dst_address.as_u32 = s1->ext_host_addr.as_u32;
                    }
                  tcp1->checksum = ip_csum_fold (sum1);
                  mss_clamping (sm, tcp1, &sum1);
                }
              tcp_packets++;
              if (nat44_set_tcp_session_state_i2o (sm, s1, b1, thread_index))
                goto trace01;
            }
          else if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment
                   && udp1->checksum)
            {
              new_port1 = udp1->src_port = s1->out2in.port;
              sum1 = udp1->checksum;
              sum1 =
                ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
                                dst_address);
              sum1 =
                ip_csum_update (sum1, old_port1, new_port1, ip4_header_t,
                                length);

              if (PREDICT_FALSE (is_twice_nat_session (s1)))
                {
                  sum1 = ip_csum_update (sum1, ip1->dst_address.as_u32,
                                         s1->ext_host_addr.as_u32,
                                         ip4_header_t, dst_address);
                  sum1 =
                    ip_csum_update (sum1,
                                    vnet_buffer (b1)->ip.reass.l4_dst_port,
                                    s1->ext_host_port, ip4_header_t, length);
                  udp1->dst_port = s1->ext_host_port;
                  ip1->dst_address.as_u32 = s1->ext_host_addr.as_u32;
                }
              udp1->checksum = ip_csum_fold (sum1);
              udp_packets++;
            }
          else
            {
              if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment)
                {
                  new_port1 = udp1->src_port = s1->out2in.port;
                  if (PREDICT_FALSE (is_twice_nat_session (s1)))
                    {
                      udp1->dst_port = s1->ext_host_port;
                      ip1->dst_address.as_u32 = s1->ext_host_addr.as_u32;
                    }
                }
              udp_packets++;
            }

          /* Accounting */
          nat44_session_update_counters (s1, now,
                                         vlib_buffer_length_in_chain (vm,
                                                                      b1),
                                         thread_index);
          /* Per-user LRU list maintenance */
          nat44_session_update_lru (sm, s1, thread_index);

        trace01:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b1->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat_in2out_ed_trace_t *t =
                vlib_add_trace (vm, node, b1, sizeof (*t));
              t->is_slow_path = is_slow_path;
              t->sw_if_index = sw_if_index1;
              t->next_index = next1;
              t->session_index = ~0;
              if (s1)
                t->session_index = s1 - tsm->sessions;
            }

          pkts_processed += next1 == nat_buffer_opaque (b1)->arc_next;


          /* verify speculative enqueues, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, bi1, next0, next1);
        }

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t *b0;
          u32 next0, sw_if_index0, rx_fib_index0, iph_offset0 = 0, proto0,
            new_addr0, old_addr0;
          u16 old_port0, new_port0;
          ip4_header_t *ip0;
          udp_header_t *udp0;
          tcp_header_t *tcp0;
          icmp46_header_t *icmp0;
          snat_session_t *s0 = 0;
          clib_bihash_kv_16_8_t kv0, value0;
          ip_csum_t sum0;

          /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);

          if (is_output_feature)
            {
              // output feature fast path is enabled on the arc
              // we need new arc_next feature
              if (PREDICT_TRUE (!is_slow_path))
                vnet_feature_next (&nat_buffer_opaque (b0)->arc_next, b0);

              iph_offset0 = vnet_buffer (b0)->ip.reass.save_rewrite_length;
            }

          next0 = nat_buffer_opaque (b0)->arc_next;

          ip0 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0) +
                                  iph_offset0);

          sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
          rx_fib_index0 =
            fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
                                                 sw_if_index0);

          if (PREDICT_FALSE (ip0->ttl == 1))
            {
              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
                                           0);
              next0 = NAT_NEXT_ICMP_ERROR;
              goto trace0;
            }

          udp0 = ip4_next_header (ip0);
          tcp0 = (tcp_header_t *) udp0;
          icmp0 = (icmp46_header_t *) udp0;
          proto0 = ip_proto_to_snat_proto (ip0->protocol);

          if (is_slow_path)
            {
              if (PREDICT_FALSE (proto0 == ~0))
                {
                  s0 = nat44_ed_in2out_unknown_proto (sm, b0, ip0,
                                                      rx_fib_index0,
                                                      thread_index, now,
                                                      vm, node);
                  if (!s0)
                    next0 = NAT_NEXT_DROP;
                  other_packets++;
                  goto trace0;
                }

              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                {
                  next0 = icmp_in2out_ed_slow_path
                    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0,
                     node, next0, now, thread_index, &s0);
                  icmp_packets++;
                  goto trace0;
                }
            }
          else
            {
              if (PREDICT_FALSE (proto0 == ~0))
                {
                  next0 = def_slow;
                  goto trace0;
                }

              if (is_output_feature)
                {
                  if (PREDICT_FALSE
                      (nat_not_translate_output_feature_fwd
                       (sm, ip0, thread_index, now, vm, b0)))
                    goto trace0;
                }

              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                {
                  next0 = def_slow;
                  goto trace0;
                }
            }

          make_ed_kv (&kv0, &ip0->src_address, &ip0->dst_address,
                      ip0->protocol, rx_fib_index0,
                      vnet_buffer (b0)->ip.reass.l4_src_port,
                      vnet_buffer (b0)->ip.reass.l4_dst_port);

          if (clib_bihash_search_16_8 (&tsm->in2out_ed, &kv0, &value0))
            {
              if (is_slow_path)
                {
                  if (is_output_feature)
                    {
                      if (PREDICT_FALSE
                          (nat44_ed_not_translate_output_feature
                           (sm, ip0, ip0->protocol,
                            vnet_buffer (b0)->ip.reass.l4_src_port,
                            vnet_buffer (b0)->ip.reass.l4_dst_port,
                            thread_index, sw_if_index0,
                            vnet_buffer (b0)->sw_if_index[VLIB_TX])))
                        goto trace0;

                      /*
                       * Send DHCP packets to the ipv4 stack, or we won't
                       * be able to use dhcp client on the outside interface
                       */
                      if (PREDICT_FALSE
                          ((b0->flags & VNET_BUFFER_F_LOCALLY_ORIGINATED)
                           && proto0 == SNAT_PROTOCOL_UDP
                           && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
                               clib_host_to_net_u16
                               (UDP_DST_PORT_dhcp_to_server))))
                        goto trace0;
                    }
                  else
                    {
                      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node,
                                                                 sw_if_index0,
                                                                 ip0,
                                                                 proto0,
                                                                 rx_fib_index0,
                                                                 thread_index)))
                        goto trace0;
                    }

                  next0 =
                    slow_path_ed (sm, b0, rx_fib_index0, &kv0, &s0, node,
                                  next0, thread_index, now);

                  if (PREDICT_FALSE (next0 == NAT_NEXT_DROP))
                    goto trace0;

                  if (PREDICT_FALSE (!s0))
                    goto trace0;
                }
              else
                {
                  next0 = def_slow;
                  goto trace0;
                }
            }
          else
            {
              s0 = pool_elt_at_index (tsm->sessions, value0.value);
            }

          b0->flags |= VNET_BUFFER_F_IS_NATED;

          if (!is_output_feature)
            vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index;

          old_addr0 = ip0->src_address.as_u32;
          new_addr0 = ip0->src_address.as_u32 = s0->out2in.addr.as_u32;
          sum0 = ip0->checksum;
          sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                 src_address);
          if (PREDICT_FALSE (is_twice_nat_session (s0)))
            sum0 = ip_csum_update (sum0, ip0->dst_address.as_u32,
                                   s0->ext_host_addr.as_u32, ip4_header_t,
                                   dst_address);
          ip0->checksum = ip_csum_fold (sum0);

          old_port0 = vnet_buffer (b0)->ip.reass.l4_src_port;

          if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
            {
              if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
                {
                  new_port0 = udp0->src_port = s0->out2in.port;
                  sum0 = tcp0->checksum;
                  sum0 =
                    ip_csum_update (sum0, old_addr0, new_addr0,
                                    ip4_header_t, dst_address);
                  sum0 =
                    ip_csum_update (sum0, old_port0, new_port0,
                                    ip4_header_t, length);
                  if (PREDICT_FALSE (is_twice_nat_session (s0)))
                    {
                      sum0 =
                        ip_csum_update (sum0, ip0->dst_address.as_u32,
                                        s0->ext_host_addr.as_u32,
                                        ip4_header_t, dst_address);
                      sum0 =
                        ip_csum_update (sum0,
                                        vnet_buffer (b0)->ip.
                                        reass.l4_dst_port, s0->ext_host_port,
                                        ip4_header_t, length);
                      tcp0->dst_port = s0->ext_host_port;
                      ip0->dst_address.as_u32 = s0->ext_host_addr.as_u32;
                    }
                  mss_clamping (sm, tcp0, &sum0);
                  tcp0->checksum = ip_csum_fold (sum0);
                }
              tcp_packets++;
              if (nat44_set_tcp_session_state_i2o (sm, s0, b0, thread_index))
                goto trace0;
            }
          else if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment
                   && udp0->checksum)
            {
              new_port0 = udp0->src_port = s0->out2in.port;
              sum0 = udp0->checksum;
              sum0 =
                ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                dst_address);
              sum0 =
                ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
                                length);
              if (PREDICT_FALSE (is_twice_nat_session (s0)))
                {
                  sum0 = ip_csum_update (sum0, ip0->dst_address.as_u32,
                                         s0->ext_host_addr.as_u32,
                                         ip4_header_t, dst_address);
                  sum0 =
                    ip_csum_update (sum0,
                                    vnet_buffer (b0)->ip.reass.l4_dst_port,
                                    s0->ext_host_port, ip4_header_t, length);
                  udp0->dst_port = s0->ext_host_port;
                  ip0->dst_address.as_u32 = s0->ext_host_addr.as_u32;
                }
              udp0->checksum = ip_csum_fold (sum0);
              udp_packets++;
            }
          else
            {
              if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
                {
                  new_port0 = udp0->src_port = s0->out2in.port;
                  if (PREDICT_FALSE (is_twice_nat_session (s0)))
                    {
                      udp0->dst_port = s0->ext_host_port;
                      ip0->dst_address.as_u32 = s0->ext_host_addr.as_u32;
                    }
                  udp_packets++;
                }
            }

          /* Accounting */
          nat44_session_update_counters (s0, now,
                                         vlib_buffer_length_in_chain
                                         (vm, b0), thread_index);
          /* Per-user LRU list maintenance */
          nat44_session_update_lru (sm, s0, thread_index);

        trace0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat_in2out_ed_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->is_slow_path = is_slow_path;
              t->sw_if_index = sw_if_index0;
              t->next_index = next0;
              t->session_index = ~0;
              if (s0)
                t->session_index = s0 - tsm->sessions;
            }

          pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;

          /* verify speculative enqueue, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, next0);
        }

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  vlib_node_increment_counter (vm, stats_node_index,
                               NAT_IN2OUT_ED_ERROR_IN2OUT_PACKETS,
                               pkts_processed);
  vlib_node_increment_counter (vm, stats_node_index,
                               NAT_IN2OUT_ED_ERROR_TCP_PACKETS, tcp_packets);
  vlib_node_increment_counter (vm, stats_node_index,
                               NAT_IN2OUT_ED_ERROR_UDP_PACKETS, udp_packets);
  vlib_node_increment_counter (vm, stats_node_index,
                               NAT_IN2OUT_ED_ERROR_ICMP_PACKETS,
                               icmp_packets);
  vlib_node_increment_counter (vm, stats_node_index,
                               NAT_IN2OUT_ED_ERROR_OTHER_PACKETS,
                               other_packets);
  return frame->n_vectors;
}

VLIB_NODE_FN (nat44_ed_in2out_node) (vlib_main_t * vm,
                                     vlib_node_runtime_t * node,
                                     vlib_frame_t * frame)
{
  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 0, 0);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_ed_in2out_node) = {
  .name = "nat44-ed-in2out",
  .vector_size = sizeof (u32),
  .sibling_of = "nat-default",
  .format_trace = format_nat_in2out_ed_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
  .error_strings = nat_in2out_ed_error_strings,
  .runtime_data_bytes = sizeof (snat_runtime_t),
};
/* *INDENT-ON* */

VLIB_NODE_FN (nat44_ed_in2out_output_node) (vlib_main_t * vm,
                                            vlib_node_runtime_t * node,
                                            vlib_frame_t * frame)
{
  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 0, 1);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_ed_in2out_output_node) = {
  .name = "nat44-ed-in2out-output",
  .vector_size = sizeof (u32),
  .sibling_of = "nat-default",
  .format_trace = format_nat_in2out_ed_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
  .error_strings = nat_in2out_ed_error_strings,
  .runtime_data_bytes = sizeof (snat_runtime_t),
};
/* *INDENT-ON* */

VLIB_NODE_FN (nat44_ed_in2out_slowpath_node) (vlib_main_t * vm,
                                              vlib_node_runtime_t *
                                              node, vlib_frame_t * frame)
{
  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 1, 0);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_ed_in2out_slowpath_node) = {
  .name = "nat44-ed-in2out-slowpath",
  .vector_size = sizeof (u32),
  .sibling_of = "nat-default",
  .format_trace = format_nat_in2out_ed_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
  .error_strings = nat_in2out_ed_error_strings,
  .runtime_data_bytes = sizeof (snat_runtime_t),
};
/* *INDENT-ON* */

VLIB_NODE_FN (nat44_ed_in2out_output_slowpath_node) (vlib_main_t * vm,
                                                     vlib_node_runtime_t
                                                     * node,
                                                     vlib_frame_t * frame)
{
  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 1, 1);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_ed_in2out_output_slowpath_node) = {
  .name = "nat44-ed-in2out-output-slowpath",
  .vector_size = sizeof (u32),
  .sibling_of = "nat-default",
  .format_trace = format_nat_in2out_ed_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
  .error_strings = nat_in2out_ed_error_strings,
  .runtime_data_bytes = sizeof (snat_runtime_t),
};
/* *INDENT-ON* */

static u8 *
format_nat_pre_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  nat_pre_trace_t *t = va_arg (*args, nat_pre_trace_t *);
  return format (s, "in2out next_index %d", t->next_index);
}

VLIB_NODE_FN (nat_pre_in2out_node)
  (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  return nat_pre_node_fn_inline (vm, node, frame,
                                 NAT_NEXT_IN2OUT_ED_FAST_PATH);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat_pre_in2out_node) = {
  .name = "nat-pre-in2out",
  .vector_size = sizeof (u32),
  .sibling_of = "nat-default",
  .format_trace = format_nat_pre_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = 0,
};
/* *INDENT-ON* */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */