nat: Final NAT44 EI/ED split patch

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

Type: refactor

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

1 files changed, 869 insertions, 0 deletions

diff --git a/src/plugins/nat/nat44-ed/nat44_ed_inlines.h b/src/plugins/nat/nat44-ed/nat44_ed_inlines.h
new file mode 100644
index 00000000000..0623940cb6d
--- /dev/null
+++ b/src/plugins/nat/nat44-ed/nat44_ed_inlines.h
@@ -0,0 +1,869 @@
+/*
+ * 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_flow_match (nat_6t_flow_t *f, vlib_buffer_t *b, ip4_address_t saddr,
+		   u16 sport, ip4_address_t daddr, u16 dport, u8 protocol,
+		   u32 fib_index)
+{
+  return f->match.daddr.as_u32 == daddr.as_u32 &&
+	 f->match.dport == vnet_buffer (b)->ip.reass.l4_dst_port &&
+	 f->match.proto == protocol && f->match.fib_index == fib_index &&
+	 f->match.saddr.as_u32 == saddr.as_u32 &&
+	 f->match.sport == vnet_buffer (b)->ip.reass.l4_src_port;
+}
+
+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:
+ */