text: /*
   * 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.
   */
  /**
   * @brief The NAT inline functions
   */
  
  #ifndef __included_nat44_ed_inlines_h__
  #define __included_nat44_ed_inlines_h__
  
  #include <float.h>
  #include <vppinfra/clib.h>
  #include <vnet/fib/ip4_fib.h>
  
  #include <nat/lib/log.h>
  #include <nat/nat44-ed/nat44_ed.h>
  
  always_inline u64
  calc_nat_key (ip4_address_t addr, u16 port, u32 fib_index, u8 proto)
  {
    ASSERT (fib_index <= (1 << 14) - 1);
    ASSERT (proto <= (1 << 3) - 1);
    return (u64) addr.as_u32 << 32 | (u64) port << 16 | fib_index << 3 |
  	 (proto & 0x7);
  }
  
  always_inline void
  split_nat_key (u64 key, ip4_address_t *addr, u16 *port, u32 *fib_index,
  	       nat_protocol_t *proto)
  {
    if (addr)
      {
        addr->as_u32 = key >> 32;
      }
    if (port)
      {
        *port = (key >> 16) & (u16) ~0;
      }
    if (fib_index)
      {
        *fib_index = key >> 3 & ((1 << 13) - 1);
      }
    if (proto)
      {
        *proto = key & 0x7;
      }
  }
  
  always_inline void
  init_nat_k (clib_bihash_kv_8_8_t *kv, ip4_address_t addr, u16 port,
  	    u32 fib_index, nat_protocol_t proto)
  {
    kv->key = calc_nat_key (addr, port, fib_index, proto);
    kv->value = ~0ULL;
  }
  
  always_inline void
  init_nat_kv (clib_bihash_kv_8_8_t *kv, ip4_address_t addr, u16 port,
  	     u32 fib_index, nat_protocol_t proto, u32 thread_index,
  	     u32 session_index)
  {
    init_nat_k (kv, addr, port, fib_index, proto);
    kv->value = (u64) thread_index << 32 | session_index;
  }
  
  always_inline void
  init_nat_i2o_k (clib_bihash_kv_8_8_t *kv, snat_session_t *s)
  {
    return init_nat_k (kv, s->in2out.addr, s->in2out.port, s->in2out.fib_index,
  		     s->nat_proto);
  }
  
  always_inline void
  init_nat_i2o_kv (clib_bihash_kv_8_8_t *kv, snat_session_t *s, u32 thread_index,
  		 u32 session_index)
  {
    init_nat_k (kv, s->in2out.addr, s->in2out.port, s->in2out.fib_index,
  	      s->nat_proto);
    kv->value = (u64) thread_index << 32 | session_index;
  }
  
  always_inline void
  init_nat_o2i_k (clib_bihash_kv_8_8_t *kv, snat_session_t *s)
  {
    return init_nat_k (kv, s->out2in.addr, s->out2in.port, s->out2in.fib_index,
  		     s->nat_proto);
  }
  
  always_inline void
  init_nat_o2i_kv (clib_bihash_kv_8_8_t *kv, snat_session_t *s, u32 thread_index,
  		 u32 session_index)
  {
    init_nat_k (kv, s->out2in.addr, s->out2in.port, s->out2in.fib_index,
  	      s->nat_proto);
    kv->value = (u64) thread_index << 32 | session_index;
  }
  
  always_inline u32
  nat_value_get_thread_index (clib_bihash_kv_8_8_t *value)
  {
    return value->value >> 32;
  }
  
  always_inline u32
  nat_value_get_session_index (clib_bihash_kv_8_8_t *value)
  {
    return value->value & ~(u32) 0;
  }
  
  always_inline void
  init_ed_k (clib_bihash_kv_16_8_t *kv, ip4_address_t l_addr, u16 l_port,
  	   ip4_address_t r_addr, u16 r_port, u32 fib_index, u8 proto)
  {
    kv->key[0] = (u64) r_addr.as_u32 << 32 | l_addr.as_u32;
    kv->key[1] =
      (u64) r_port << 48 | (u64) l_port << 32 | fib_index << 8 | proto;
  }
  
  always_inline void
  init_ed_kv (clib_bihash_kv_16_8_t *kv, ip4_address_t l_addr, u16 l_port,
  	    ip4_address_t r_addr, u16 r_port, u32 fib_index, u8 proto,
  	    u32 thread_index, u32 session_index)
  {
    init_ed_k (kv, l_addr, l_port, r_addr, r_port, fib_index, proto);
    kv->value = (u64) thread_index << 32 | session_index;
  }
  
  always_inline u32
  ed_value_get_thread_index (clib_bihash_kv_16_8_t *value)
  {
    return value->value >> 32;
  }
  
  always_inline u32
  ed_value_get_session_index (clib_bihash_kv_16_8_t *value)
  {
    return value->value & ~(u32) 0;
  }
  
  always_inline void
  split_ed_kv (clib_bihash_kv_16_8_t *kv, ip4_address_t *l_addr,
  	     ip4_address_t *r_addr, u8 *proto, u32 *fib_index, u16 *l_port,
  	     u16 *r_port)
  {
    if (l_addr)
      {
        l_addr->as_u32 = kv->key[0] & (u32) ~0;
      }
    if (r_addr)
      {
        r_addr->as_u32 = kv->key[0] >> 32;
      }
    if (r_port)
      {
        *r_port = kv->key[1] >> 48;
      }
    if (l_port)
      {
        *l_port = (kv->key[1] >> 32) & (u16) ~0;
      }
    if (fib_index)
      {
        *fib_index = (kv->key[1] >> 8) & ((1 << 24) - 1);
      }
    if (proto)
      {
        *proto = kv->key[1] & (u8) ~0;
      }
  }
  
  static_always_inline int
  nat_get_icmp_session_lookup_values (vlib_buffer_t *b, ip4_header_t *ip0,
  				    ip4_address_t *lookup_saddr,
  				    u16 *lookup_sport,
  				    ip4_address_t *lookup_daddr,
  				    u16 *lookup_dport, u8 *lookup_protocol)
  {
    icmp46_header_t *icmp0;
    icmp_echo_header_t *echo0, *inner_echo0 = 0;
    ip4_header_t *inner_ip0 = 0;
    void *l4_header = 0;
    icmp46_header_t *inner_icmp0;
  
    icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
    echo0 = (icmp_echo_header_t *) (icmp0 + 1);
  
    // avoid warning about unused variables in caller by setting to bogus values
    *lookup_sport = 0;
    *lookup_dport = 0;
  
    if (!icmp_type_is_error_message (
  	vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags))
      {
        *lookup_protocol = IP_PROTOCOL_ICMP;
        lookup_saddr->as_u32 = ip0->src_address.as_u32;
        *lookup_sport = vnet_buffer (b)->ip.reass.l4_src_port;
        lookup_daddr->as_u32 = ip0->dst_address.as_u32;
        *lookup_dport = vnet_buffer (b)->ip.reass.l4_dst_port;
      }
    else
      {
        inner_ip0 = (ip4_header_t *) (echo0 + 1);
        l4_header = ip4_next_header (inner_ip0);
        *lookup_protocol = inner_ip0->protocol;
        lookup_saddr->as_u32 = inner_ip0->dst_address.as_u32;
        lookup_daddr->as_u32 = inner_ip0->src_address.as_u32;
        switch (ip_proto_to_nat_proto (inner_ip0->protocol))
  	{
  	case NAT_PROTOCOL_ICMP:
  	  inner_icmp0 = (icmp46_header_t *) l4_header;
  	  inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
  	  *lookup_sport = inner_echo0->identifier;
  	  *lookup_dport = inner_echo0->identifier;
  	  break;
  	case NAT_PROTOCOL_UDP:
  	case NAT_PROTOCOL_TCP:
  	  *lookup_sport = ((tcp_udp_header_t *) l4_header)->dst_port;
  	  *lookup_dport = ((tcp_udp_header_t *) l4_header)->src_port;
  	  break;
  	default:
  	  return NAT_IN2OUT_ED_ERROR_UNSUPPORTED_PROTOCOL;
  	}
      }
    return 0;
  }
  
  always_inline u32
  nat44_session_get_timeout (snat_main_t *sm, snat_session_t *s)
  {
    switch (s->nat_proto)
      {
      case NAT_PROTOCOL_ICMP:
        return sm->timeouts.icmp;
      case NAT_PROTOCOL_UDP:
        return sm->timeouts.udp;
      case NAT_PROTOCOL_TCP:
        {
  	if (s->state)
  	  return sm->timeouts.tcp.transitory;
  	else
  	  return sm->timeouts.tcp.established;
        }
      default:
        return sm->timeouts.udp;
      }
  
    return 0;
  }
  
  static_always_inline u8
  nat44_ed_maximum_sessions_exceeded (snat_main_t *sm, u32 fib_index,
  				    u32 thread_index)
  {
    u32 translations;
    translations = pool_elts (sm->per_thread_data[thread_index].sessions);
    if (vec_len (sm->max_translations_per_fib) <= fib_index)
      fib_index = 0;
    return translations >= sm->max_translations_per_fib[fib_index];
  }
  
  static_always_inline int
  nat_ed_lru_insert (snat_main_per_thread_data_t *tsm, snat_session_t *s,
  		   f64 now, u8 proto)
  {
    dlist_elt_t *lru_list_elt;
    pool_get (tsm->lru_pool, lru_list_elt);
    s->lru_index = lru_list_elt - tsm->lru_pool;
    switch (proto)
      {
      case IP_PROTOCOL_UDP:
        s->lru_head_index = tsm->udp_lru_head_index;
        break;
      case IP_PROTOCOL_TCP:
        s->lru_head_index = tsm->tcp_trans_lru_head_index;
        break;
      case IP_PROTOCOL_ICMP:
        s->lru_head_index = tsm->icmp_lru_head_index;
        break;
      default:
        s->lru_head_index = tsm->unk_proto_lru_head_index;
        break;
      }
    clib_dlist_addtail (tsm->lru_pool, s->lru_head_index, s->lru_index);
    lru_list_elt->value = s - tsm->sessions;
    s->last_lru_update = now;
    return 1;
  }
  
  static_always_inline void
  nat_6t_flow_to_ed_k (clib_bihash_kv_16_8_t *kv, nat_6t_flow_t *f)
  {
    init_ed_k (kv, f->match.saddr, f->match.sport, f->match.daddr,
  	     f->match.dport, f->match.fib_index, f->match.proto);
  }
  
  static_always_inline void
  nat_6t_flow_to_ed_kv (clib_bihash_kv_16_8_t *kv, nat_6t_flow_t *f,
  		      u32 thread_idx, u32 session_idx)
  {
    init_ed_kv (kv, f->match.saddr, f->match.sport, f->match.daddr,
  	      f->match.dport, f->match.fib_index, f->match.proto, thread_idx,
  	      session_idx);
  }
  
  static_always_inline int
  nat_ed_ses_i2o_flow_hash_add_del (snat_main_t *sm, u32 thread_idx,
  				  snat_session_t *s, int is_add)
  {
    snat_main_per_thread_data_t *tsm =
      vec_elt_at_index (sm->per_thread_data, thread_idx);
    clib_bihash_kv_16_8_t kv;
    if (0 == is_add)
      {
        nat_6t_flow_to_ed_k (&kv, &s->i2o);
      }
    else
      {
        nat_6t_flow_to_ed_kv (&kv, &s->i2o, thread_idx, s - tsm->sessions);
        nat_6t_l3_l4_csum_calc (&s->i2o);
      }
    return clib_bihash_add_del_16_8 (&sm->flow_hash, &kv, is_add);
  }
  
  static_always_inline int
  nat_ed_ses_o2i_flow_hash_add_del (snat_main_t *sm, u32 thread_idx,
  				  snat_session_t *s, int is_add)
  {
    snat_main_per_thread_data_t *tsm =
      vec_elt_at_index (sm->per_thread_data, thread_idx);
    clib_bihash_kv_16_8_t kv;
    if (0 == is_add)
      {
        nat_6t_flow_to_ed_k (&kv, &s->o2i);
      }
    else
      {
        nat_6t_flow_to_ed_kv (&kv, &s->o2i, thread_idx, s - tsm->sessions);
        nat_6t_l3_l4_csum_calc (&s->o2i);
      }
    return clib_bihash_add_del_16_8 (&sm->flow_hash, &kv, is_add);
  }
  
  always_inline void
  nat_ed_session_delete (snat_main_t *sm, snat_session_t *ses, u32 thread_index,
  		       int lru_delete
  		       /* delete from global LRU list */)
  {
    snat_main_per_thread_data_t *tsm =
      vec_elt_at_index (sm->per_thread_data, thread_index);
  
    if (lru_delete)
      {
        clib_dlist_remove (tsm->lru_pool, ses->lru_index);
      }
    pool_put_index (tsm->lru_pool, ses->lru_index);
    if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, ses, 0))
      nat_elog_warn (sm, "flow hash del failed");
    if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, ses, 0))
      nat_elog_warn (sm, "flow hash del failed");
    pool_put (tsm->sessions, ses);
    vlib_set_simple_counter (&sm->total_sessions, thread_index, 0,
  			   pool_elts (tsm->sessions));
  }
  
  static_always_inline int
  nat_lru_free_one_with_head (snat_main_t *sm, int thread_index, f64 now,
  			    u32 head_index)
  {
    snat_session_t *s = NULL;
    dlist_elt_t *oldest_elt;
    f64 sess_timeout_time;
    u32 oldest_index;
    snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
    oldest_index = clib_dlist_remove_head (tsm->lru_pool, head_index);
    if (~0 != oldest_index)
      {
        oldest_elt = pool_elt_at_index (tsm->lru_pool, oldest_index);
        s = pool_elt_at_index (tsm->sessions, oldest_elt->value);
  
        sess_timeout_time =
  	s->last_heard + (f64) nat44_session_get_timeout (sm, s);
        if (now >= sess_timeout_time ||
  	  (s->tcp_closed_timestamp && now >= s->tcp_closed_timestamp))
  	{
  	  nat_free_session_data (sm, s, thread_index, 0);
  	  nat_ed_session_delete (sm, s, thread_index, 0);
  	  return 1;
  	}
        else
  	{
  	  clib_dlist_addhead (tsm->lru_pool, head_index, oldest_index);
  	}
      }
    return 0;
  }
  
  static_always_inline int
  nat_lru_free_one (snat_main_t *sm, int thread_index, f64 now)
  {
    snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
    int rc = 0;
  #define _(p)                                                                  \
    if ((rc = nat_lru_free_one_with_head (sm, thread_index, now,                \
  					tsm->p##_lru_head_index)))            \
      {                                                                         \
        return rc;                                                              \
      }
    _ (tcp_trans);
    _ (udp);
    _ (unk_proto);
    _ (icmp);
    _ (tcp_estab);
  #undef _
    return 0;
  }
  
  static_always_inline snat_session_t *
  nat_ed_session_alloc (snat_main_t *sm, u32 thread_index, f64 now, u8 proto)
  {
    snat_session_t *s;
    snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
  
    nat_lru_free_one (sm, thread_index, now);
  
    pool_get (tsm->sessions, s);
    clib_memset (s, 0, sizeof (*s));
  
    nat_ed_lru_insert (tsm, s, now, proto);
  
    s->ha_last_refreshed = now;
    vlib_set_simple_counter (&sm->total_sessions, thread_index, 0,
  			   pool_elts (tsm->sessions));
    return s;
  }
  
  // slow path
  static_always_inline void
  per_vrf_sessions_cleanup (u32 thread_index)
  {
    snat_main_t *sm = &snat_main;
    snat_main_per_thread_data_t *tsm =
      vec_elt_at_index (sm->per_thread_data, thread_index);
    per_vrf_sessions_t *per_vrf_sessions;
    u32 *to_free = 0, *i;
  
    vec_foreach (per_vrf_sessions, tsm->per_vrf_sessions_vec)
      {
        if (per_vrf_sessions->expired)
  	{
  	  if (per_vrf_sessions->ses_count == 0)
  	    {
  	      vec_add1 (to_free, per_vrf_sessions - tsm->per_vrf_sessions_vec);
  	    }
  	}
      }
  
    if (vec_len (to_free))
      {
        vec_foreach (i, to_free)
  	{
  	  vec_del1 (tsm->per_vrf_sessions_vec, *i);
  	}
      }
  
    vec_free (to_free);
  }
  
  // slow path
  static_always_inline void
  per_vrf_sessions_register_session (snat_session_t *s, u32 thread_index)
  {
    snat_main_t *sm = &snat_main;
    snat_main_per_thread_data_t *tsm =
      vec_elt_at_index (sm->per_thread_data, thread_index);
    per_vrf_sessions_t *per_vrf_sessions;
  
    per_vrf_sessions_cleanup (thread_index);
  
    // s->per_vrf_sessions_index == ~0 ... reuse of old session
  
    vec_foreach (per_vrf_sessions, tsm->per_vrf_sessions_vec)
      {
        // ignore already expired registrations
        if (per_vrf_sessions->expired)
  	continue;
  
        if ((s->in2out.fib_index == per_vrf_sessions->rx_fib_index) &&
  	  (s->out2in.fib_index == per_vrf_sessions->tx_fib_index))
  	{
  	  goto done;
  	}
        if ((s->in2out.fib_index == per_vrf_sessions->tx_fib_index) &&
  	  (s->out2in.fib_index == per_vrf_sessions->rx_fib_index))
  	{
  	  goto done;
  	}
      }
  
    // create a new registration
    vec_add2 (tsm->per_vrf_sessions_vec, per_vrf_sessions, 1);
    clib_memset (per_vrf_sessions, 0, sizeof (*per_vrf_sessions));
  
    per_vrf_sessions->rx_fib_index = s->in2out.fib_index;
    per_vrf_sessions->tx_fib_index = s->out2in.fib_index;
  
  done:
    s->per_vrf_sessions_index = per_vrf_sessions - tsm->per_vrf_sessions_vec;
    per_vrf_sessions->ses_count++;
  }
  
  // fast path
  static_always_inline void
  per_vrf_sessions_unregister_session (snat_session_t *s, u32 thread_index)
  {
    snat_main_t *sm = &snat_main;
    snat_main_per_thread_data_t *tsm;
    per_vrf_sessions_t *per_vrf_sessions;
  
    ASSERT (s->per_vrf_sessions_index != ~0);
  
    tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
    per_vrf_sessions =
      vec_elt_at_index (tsm->per_vrf_sessions_vec, s->per_vrf_sessions_index);
  
    ASSERT (per_vrf_sessions->ses_count != 0);
  
    per_vrf_sessions->ses_count--;
    s->per_vrf_sessions_index = ~0;
  }
  
  // fast path
  static_always_inline u8
  per_vrf_sessions_is_expired (snat_session_t *s, u32 thread_index)
  {
    snat_main_t *sm = &snat_main;
    snat_main_per_thread_data_t *tsm;
    per_vrf_sessions_t *per_vrf_sessions;
  
    ASSERT (s->per_vrf_sessions_index != ~0);
  
    tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
    per_vrf_sessions =
      vec_elt_at_index (tsm->per_vrf_sessions_vec, s->per_vrf_sessions_index);
    return per_vrf_sessions->expired;
  }
  
  static_always_inline void
  nat_6t_flow_init (nat_6t_flow_t *f, u32 thread_idx, ip4_address_t saddr,
  		  u16 sport, ip4_address_t daddr, u16 dport, u32 fib_index,
  		  u8 proto, u32 session_idx)
  {
    clib_memset (f, 0, sizeof (*f));
    f->match.saddr = saddr;
    f->match.sport = sport;
    f->match.daddr = daddr;
    f->match.dport = dport;
    f->match.proto = proto;
    f->match.fib_index = fib_index;
  }
  
  static_always_inline void
  nat_6t_i2o_flow_init (snat_main_t *sm, u32 thread_idx, snat_session_t *s,
  		      ip4_address_t saddr, u16 sport, ip4_address_t daddr,
  		      u16 dport, u32 fib_index, u8 proto)
  {
    snat_main_per_thread_data_t *tsm =
      vec_elt_at_index (sm->per_thread_data, thread_idx);
    nat_6t_flow_init (&s->i2o, thread_idx, saddr, sport, daddr, dport, fib_index,
  		    proto, s - tsm->sessions);
  }
  
  static_always_inline void
  nat_6t_o2i_flow_init (snat_main_t *sm, u32 thread_idx, snat_session_t *s,
  		      ip4_address_t saddr, u16 sport, ip4_address_t daddr,
  		      u16 dport, u32 fib_index, u8 proto)
  {
    snat_main_per_thread_data_t *tsm =
      vec_elt_at_index (sm->per_thread_data, thread_idx);
    nat_6t_flow_init (&s->o2i, thread_idx, saddr, sport, daddr, dport, fib_index,
  		    proto, s - tsm->sessions);
  }
  
  static_always_inline int
  nat_6t_t_eq (nat_6t_t *t1, nat_6t_t *t2)
  {
    return t1->as_u64[0] == t2->as_u64[0] && t1->as_u64[1] == t2->as_u64[1];
  }
  
  static inline uword
  nat_pre_node_fn_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
  			vlib_frame_t *frame, u32 def_next)
  {
    u32 n_left_from, *from;
  
    from = vlib_frame_vector_args (frame);
    n_left_from = frame->n_vectors;
  
    vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
    u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
    vlib_get_buffers (vm, from, b, n_left_from);
  
    while (n_left_from >= 2)
      {
        u32 next0, next1;
        u32 arc_next0, arc_next1;
        vlib_buffer_t *b0, *b1;
  
        b0 = *b;
        b++;
        b1 = *b;
        b++;
  
        /* Prefetch next iteration. */
        if (PREDICT_TRUE (n_left_from >= 4))
  	{
  	  vlib_buffer_t *p2, *p3;
  
  	  p2 = *b;
  	  p3 = *(b + 1);
  
  	  vlib_prefetch_buffer_header (p2, LOAD);
  	  vlib_prefetch_buffer_header (p3, LOAD);
  
  	  CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, LOAD);
  	  CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, LOAD);
  	}
  
        next0 = def_next;
        next1 = def_next;
  
        vnet_feature_next (&arc_next0, b0);
        vnet_feature_next (&arc_next1, b1);
  
        vnet_buffer2 (b0)->nat.arc_next = arc_next0;
        vnet_buffer2 (b1)->nat.arc_next = arc_next1;
  
        if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
  	{
  	  if (b0->flags & VLIB_BUFFER_IS_TRACED)
  	    {
  	      nat_pre_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
  	      t->next_index = next0;
  	      t->arc_next_index = arc_next0;
  	    }
  	  if (b1->flags & VLIB_BUFFER_IS_TRACED)
  	    {
  	      nat_pre_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
  	      t->next_index = next1;
  	      t->arc_next_index = arc_next1;
  	    }
  	}
  
        n_left_from -= 2;
        next[0] = next0;
        next[1] = next1;
        next += 2;
      }
  
    while (n_left_from > 0)
      {
        u32 next0;
        u32 arc_next0;
        vlib_buffer_t *b0;
  
        b0 = *b;
        b++;
  
        next0 = def_next;
        vnet_feature_next (&arc_next0, b0);
        vnet_buffer2 (b0)->nat.arc_next = arc_next0;
  
        if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
  			 (b0->flags & VLIB_BUFFER_IS_TRACED)))
  	{
  	  nat_pre_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
  	  t->next_index = next0;
  	  t->arc_next_index = arc_next0;
  	}
  
        n_left_from--;
        next[0] = next0;
        next++;
      }
    vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
  			       frame->n_vectors);
  
    return frame->n_vectors;
  }
  
  static_always_inline u16
  snat_random_port (u16 min, u16 max)
  {
    snat_main_t *sm = &snat_main;
    u32 rwide;
    u16 r;
  
    rwide = random_u32 (&sm->random_seed);
    r = rwide & 0xFFFF;
    if (r >= min && r <= max)
      return r;
  
    return min + (rwide % (max - min + 1));
  }
  
  always_inline u8
  is_interface_addr (snat_main_t *sm, vlib_node_runtime_t *node,
  		   u32 sw_if_index0, u32 ip4_addr)
  {
    snat_runtime_t *rt = (snat_runtime_t *) node->runtime_data;
    ip4_address_t *first_int_addr;
  
    if (PREDICT_FALSE (rt->cached_sw_if_index != sw_if_index0))
      {
        first_int_addr = ip4_interface_first_address (
  	sm->ip4_main, sw_if_index0, 0 /* just want the address */);
        rt->cached_sw_if_index = sw_if_index0;
        if (first_int_addr)
  	rt->cached_ip4_address = first_int_addr->as_u32;
        else
  	rt->cached_ip4_address = 0;
      }
  
    if (PREDICT_FALSE (ip4_addr == rt->cached_ip4_address))
      return 1;
    else
      return 0;
  }
  
  always_inline void
  nat44_set_tcp_session_state_i2o (snat_main_t *sm, f64 now, snat_session_t *ses,
  				 vlib_buffer_t *b, u32 thread_index)
  {
    snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
    u8 tcp_flags = vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags;
    u32 tcp_ack_number = vnet_buffer (b)->ip.reass.tcp_ack_number;
    u32 tcp_seq_number = vnet_buffer (b)->ip.reass.tcp_seq_number;
    if ((ses->state == 0) && (tcp_flags & TCP_FLAG_RST))
      ses->state = NAT44_SES_RST;
    if ((ses->state == NAT44_SES_RST) && !(tcp_flags & TCP_FLAG_RST))
      ses->state = 0;
    if ((tcp_flags & TCP_FLAG_ACK) && (ses->state & NAT44_SES_I2O_SYN) &&
        (ses->state & NAT44_SES_O2I_SYN))
      ses->state = 0;
    if (tcp_flags & TCP_FLAG_SYN)
      ses->state |= NAT44_SES_I2O_SYN;
    if (tcp_flags & TCP_FLAG_FIN)
      {
        ses->i2o_fin_seq = clib_net_to_host_u32 (tcp_seq_number);
        ses->state |= NAT44_SES_I2O_FIN;
      }
    if ((tcp_flags & TCP_FLAG_ACK) && (ses->state & NAT44_SES_O2I_FIN))
      {
        if (clib_net_to_host_u32 (tcp_ack_number) > ses->o2i_fin_seq)
  	{
  	  ses->state |= NAT44_SES_O2I_FIN_ACK;
  	  if (nat44_is_ses_closed (ses))
  	    { // if session is now closed, save the timestamp
  	      ses->tcp_closed_timestamp = now + sm->timeouts.tcp.transitory;
  	      ses->last_lru_update = now;
  	    }
  	}
      }
  
    // move the session to proper LRU
    if (ses->state)
      {
        ses->lru_head_index = tsm->tcp_trans_lru_head_index;
      }
    else
      {
        ses->lru_head_index = tsm->tcp_estab_lru_head_index;
      }
    clib_dlist_remove (tsm->lru_pool, ses->lru_index);
    clib_dlist_addtail (tsm->lru_pool, ses->lru_head_index, ses->lru_index);
  }
  
  always_inline void
  nat44_set_tcp_session_state_o2i (snat_main_t *sm, f64 now, snat_session_t *ses,
  				 u8 tcp_flags, u32 tcp_ack_number,
  				 u32 tcp_seq_number, u32 thread_index)
  {
    snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
    if ((ses->state == 0) && (tcp_flags & TCP_FLAG_RST))
      ses->state = NAT44_SES_RST;
    if ((ses->state == NAT44_SES_RST) && !(tcp_flags & TCP_FLAG_RST))
      ses->state = 0;
    if ((tcp_flags & TCP_FLAG_ACK) && (ses->state & NAT44_SES_I2O_SYN) &&
        (ses->state & NAT44_SES_O2I_SYN))
      ses->state = 0;
    if (tcp_flags & TCP_FLAG_SYN)
      ses->state |= NAT44_SES_O2I_SYN;
    if (tcp_flags & TCP_FLAG_FIN)
      {
        ses->o2i_fin_seq = clib_net_to_host_u32 (tcp_seq_number);
        ses->state |= NAT44_SES_O2I_FIN;
      }
    if ((tcp_flags & TCP_FLAG_ACK) && (ses->state & NAT44_SES_I2O_FIN))
      {
        if (clib_net_to_host_u32 (tcp_ack_number) > ses->i2o_fin_seq)
  	ses->state |= NAT44_SES_I2O_FIN_ACK;
        if (nat44_is_ses_closed (ses))
  	{ // if session is now closed, save the timestamp
  	  ses->tcp_closed_timestamp = now + sm->timeouts.tcp.transitory;
  	  ses->last_lru_update = now;
  	}
      }
    // move the session to proper LRU
    if (ses->state)
      {
        ses->lru_head_index = tsm->tcp_trans_lru_head_index;
      }
    else
      {
        ses->lru_head_index = tsm->tcp_estab_lru_head_index;
      }
    clib_dlist_remove (tsm->lru_pool, ses->lru_index);
    clib_dlist_addtail (tsm->lru_pool, ses->lru_head_index, ses->lru_index);
  }
  
  always_inline void
  nat44_session_update_counters (snat_session_t *s, f64 now, uword bytes,
  			       u32 thread_index)
  {
    s->last_heard = now;
    s->total_pkts++;
    s->total_bytes += bytes;
  }
  
  /** \brief Per-user LRU list maintenance */
  always_inline void
  nat44_session_update_lru (snat_main_t *sm, snat_session_t *s, u32 thread_index)
  {
    /* don't update too often - timeout is in magnitude of seconds anyway */
    if (s->last_heard > s->last_lru_update + 1)
      {
        clib_dlist_remove (sm->per_thread_data[thread_index].lru_pool,
  			 s->lru_index);
        clib_dlist_addtail (sm->per_thread_data[thread_index].lru_pool,
  			  s->lru_head_index, s->lru_index);
        s->last_lru_update = s->last_heard;
      }
  }
  
  #endif /* __included_nat44_ed_inlines_h__ */
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  