nat44_ed_inlines.h

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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.
 */
/**
 * @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);
    }

  ASSERT (thread_idx == s->thread_index);
  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);
    }
  ASSERT (thread_idx == s->thread_index);
  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));
#if CLIB_ASSERT_ENABLE
  s->thread_index = thread_index;
#endif
  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:
 */