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, 1443 insertions, 0 deletions

diff --git a/src/plugins/nat/nat44-ed/nat44_ed_out2in.c b/src/plugins/nat/nat44-ed/nat44_ed_out2in.c
new file mode 100644
index 00000000000..4d354d3e8ec
--- /dev/null
+++ b/src/plugins/nat/nat44-ed/nat44_ed_out2in.c
@@ -0,0 +1,1443 @@
+/*
+ * 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 outside to inside network translation
+ */
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/udp/udp_local.h>
+#include <vppinfra/error.h>
+
+#include <nat/lib/nat_syslog.h>
+#include <nat/lib/ipfix_logging.h>
+
+#include <nat/nat44-ed/nat44_ed.h>
+#include <nat/nat44-ed/nat44_ed_inlines.h>
+
+static char *nat_out2in_ed_error_strings[] = {
+#define _(sym,string) string,
+  foreach_nat_out2in_ed_error
+#undef _
+};
+
+typedef struct
+{
+  u32 sw_if_index;
+  u32 next_index;
+  u32 session_index;
+  nat_translation_error_e translation_error;
+  nat_6t_flow_t i2of;
+  nat_6t_flow_t o2if;
+  clib_bihash_kv_16_8_t search_key;
+  u8 is_slow_path;
+  u8 translation_via_i2of;
+  u8 lookup_skipped;
+} nat44_ed_out2in_trace_t;
+
+static u8 *
+format_nat44_ed_out2in_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 *);
+  nat44_ed_out2in_trace_t *t = va_arg (*args, nat44_ed_out2in_trace_t *);
+  char *tag;
+
+  tag =
+    t->is_slow_path ? "NAT44_OUT2IN_ED_SLOW_PATH" :
+    "NAT44_OUT2IN_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);
+  if (~0 != t->session_index)
+    {
+      s = format (s, ", translation result '%U' via %s",
+		  format_nat_ed_translation_error, t->translation_error,
+		  t->translation_via_i2of ? "i2of" : "o2if");
+      s = format (s, "\n  i2of %U", format_nat_6t_flow, &t->i2of);
+      s = format (s, "\n  o2if %U", format_nat_6t_flow, &t->o2if);
+    }
+  if (!t->is_slow_path)
+    {
+      if (t->lookup_skipped)
+	{
+	  s = format (s, "\n lookup skipped - cached session index used");
+	}
+      else
+	{
+	  s = format (s, "\n  search key %U", format_ed_session_kvp,
+		      &t->search_key);
+	}
+    }
+
+  return s;
+}
+
+static int
+next_src_nat (snat_main_t *sm, ip4_header_t *ip, u16 src_port, u16 dst_port,
+	      u32 thread_index, u32 rx_fib_index)
+{
+  clib_bihash_kv_16_8_t kv, value;
+
+  init_ed_k (&kv, ip->src_address, src_port, ip->dst_address, dst_port,
+	     rx_fib_index, ip->protocol);
+  if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
+    return 1;
+
+  return 0;
+}
+
+static void create_bypass_for_fwd (snat_main_t *sm, vlib_buffer_t *b,
+				   snat_session_t *s, ip4_header_t *ip,
+				   u32 rx_fib_index, u32 thread_index);
+
+static snat_session_t *create_session_for_static_mapping_ed (
+  snat_main_t *sm, vlib_buffer_t *b, ip4_address_t i2o_addr, u16 i2o_port,
+  u32 i2o_fib_index, ip4_address_t o2i_addr, u16 o2i_port, u32 o2i_fib_index,
+  nat_protocol_t nat_proto, vlib_node_runtime_t *node, u32 rx_fib_index,
+  u32 thread_index, twice_nat_type_t twice_nat, lb_nat_type_t lb_nat, f64 now,
+  snat_static_mapping_t *mapping);
+
+static inline u32
+icmp_out2in_ed_slow_path (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
+			  icmp46_header_t *icmp, u32 sw_if_index,
+			  u32 rx_fib_index, vlib_node_runtime_t *node,
+			  u32 next, f64 now, u32 thread_index,
+			  snat_session_t **s_p)
+{
+  vlib_main_t *vm = vlib_get_main ();
+
+  ip_csum_t sum;
+  u16 checksum;
+
+  snat_session_t *s = 0;
+  u8 is_addr_only, identity_nat;
+  ip4_address_t sm_addr;
+  u16 sm_port;
+  u32 sm_fib_index;
+  snat_static_mapping_t *m;
+  u8 lookup_protocol;
+  ip4_address_t lookup_saddr, lookup_daddr;
+  u16 lookup_sport, lookup_dport;
+
+  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);
+
+  if (nat_get_icmp_session_lookup_values (b, ip, &lookup_saddr, &lookup_sport,
+					  &lookup_daddr, &lookup_dport,
+					  &lookup_protocol))
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_UNSUPPORTED_PROTOCOL];
+      next = NAT_NEXT_DROP;
+      goto out;
+    }
+
+  if (snat_static_mapping_match (
+	sm, ip->dst_address, lookup_sport, rx_fib_index,
+	ip_proto_to_nat_proto (ip->protocol), &sm_addr, &sm_port,
+	&sm_fib_index, 1, &is_addr_only, 0, 0, 0, &identity_nat, &m))
+    {
+      // static mapping not matched
+      if (!sm->forwarding_enabled)
+	{
+	  /* Don't NAT packet aimed at the intfc address */
+	  if (!is_interface_addr (sm, node, sw_if_index,
+				  ip->dst_address.as_u32))
+	    {
+	      b->error = node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
+	      next = NAT_NEXT_DROP;
+	    }
+	}
+      else
+	{
+	  if (next_src_nat (sm, ip, lookup_sport, lookup_dport, thread_index,
+			    rx_fib_index))
+	    {
+	      next = NAT_NEXT_IN2OUT_ED_FAST_PATH;
+	    }
+	  else
+	    {
+	      create_bypass_for_fwd (sm, b, s, ip, rx_fib_index, thread_index);
+	    }
+	}
+      goto out;
+    }
+
+  if (PREDICT_FALSE (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
+		       ICMP4_echo_reply &&
+		     (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
+			ICMP4_echo_request ||
+		      !is_addr_only)))
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_BAD_ICMP_TYPE];
+      next = NAT_NEXT_DROP;
+      goto out;
+    }
+
+  if (PREDICT_FALSE (identity_nat))
+    {
+      goto out;
+    }
+
+  /* Create session initiated by host from external network */
+  s = create_session_for_static_mapping_ed (
+    sm, b, sm_addr, sm_port, sm_fib_index, ip->dst_address, lookup_sport,
+    rx_fib_index, ip_proto_to_nat_proto (lookup_protocol), node, rx_fib_index,
+    thread_index, 0, 0, vlib_time_now (vm), m);
+  if (!s)
+    next = NAT_NEXT_DROP;
+
+  if (PREDICT_TRUE (!ip4_is_fragment (ip)))
+    {
+      sum = ip_incremental_checksum_buffer (
+	vm, b, (u8 *) icmp - (u8 *) vlib_buffer_get_current (b),
+	ntohs (ip->length) - ip4_header_bytes (ip), 0);
+      checksum = ~ip_csum_fold (sum);
+      if (checksum != 0 && checksum != 0xffff)
+	{
+	  next = NAT_NEXT_DROP;
+	  goto out;
+	}
+    }
+
+  if (PREDICT_TRUE (next != NAT_NEXT_DROP && s))
+    {
+      /* 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);
+    }
+out:
+  if (NAT_NEXT_DROP == next && s)
+    {
+      nat_ed_session_delete (sm, s, thread_index, 1);
+      s = 0;
+    }
+  *s_p = s;
+  return next;
+}
+
+// allocate exact address based on preference
+static_always_inline int
+nat_alloc_addr_and_port_exact (snat_address_t * a,
+			       u32 thread_index,
+			       nat_protocol_t proto,
+			       ip4_address_t * addr,
+			       u16 * port,
+			       u16 port_per_thread, u32 snat_thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  u32 portnum;
+
+  switch (proto)
+    {
+#define _(N, j, n, s) \
+    case NAT_PROTOCOL_##N: \
+      if (a->busy_##n##_ports_per_thread[thread_index] < port_per_thread) \
+        { \
+          while (1) \
+            { \
+              portnum = (port_per_thread * \
+                snat_thread_index) + \
+                snat_random_port(0, port_per_thread - 1) + 1024; \
+              if (a->busy_##n##_port_refcounts[portnum]) \
+                continue; \
+	      --a->busy_##n##_port_refcounts[portnum]; \
+              a->busy_##n##_ports_per_thread[thread_index]++; \
+              a->busy_##n##_ports++; \
+              *addr = a->addr; \
+              *port = clib_host_to_net_u16(portnum); \
+              return 0; \
+            } \
+        } \
+      break;
+      foreach_nat_protocol
+#undef _
+	default : nat_elog_info (sm, "unknown protocol");
+      return 1;
+    }
+
+  /* Totally out of translations to use... */
+  nat_ipfix_logging_addresses_exhausted (thread_index, 0);
+  return 1;
+}
+
+static_always_inline int
+nat44_ed_alloc_outside_addr_and_port (snat_address_t *addresses, u32 fib_index,
+				      u32 thread_index, nat_protocol_t proto,
+				      ip4_address_t *addr, u16 *port,
+				      u16 port_per_thread,
+				      u32 snat_thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_address_t *a, *ga = 0;
+  u32 portnum;
+  int i;
+
+  for (i = 0; i < vec_len (addresses); i++)
+    {
+      a = addresses + i;
+      switch (proto)
+	{
+#define _(N, j, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    if (a->busy_##n##_ports_per_thread[thread_index] < port_per_thread)       \
+      {                                                                       \
+	if (a->fib_index == fib_index)                                        \
+	  {                                                                   \
+	    while (1)                                                         \
+	      {                                                               \
+		portnum = (port_per_thread * snat_thread_index) +             \
+			  snat_random_port (0, port_per_thread - 1) + 1024;   \
+		if (a->busy_##n##_port_refcounts[portnum])                    \
+		  continue;                                                   \
+		--a->busy_##n##_port_refcounts[portnum];                      \
+		a->busy_##n##_ports_per_thread[thread_index]++;               \
+		a->busy_##n##_ports++;                                        \
+		*addr = a->addr;                                              \
+		*port = clib_host_to_net_u16 (portnum);                       \
+		return 0;                                                     \
+	      }                                                               \
+	  }                                                                   \
+	else if (a->fib_index == ~0)                                          \
+	  {                                                                   \
+	    ga = a;                                                           \
+	  }                                                                   \
+      }                                                                       \
+    break;
+	  foreach_nat_protocol
+#undef _
+	    default : nat_elog_info (sm, "unknown protocol");
+	  return 1;
+	}
+    }
+
+  if (ga)
+    {
+      a = ga;
+      switch (proto)
+	{
+#define _(N, j, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    while (1)                                                                 \
+      {                                                                       \
+	portnum = (port_per_thread * snat_thread_index) +                     \
+		  snat_random_port (0, port_per_thread - 1) + 1024;           \
+	if (a->busy_##n##_port_refcounts[portnum])                            \
+	  continue;                                                           \
+	++a->busy_##n##_port_refcounts[portnum];                              \
+	a->busy_##n##_ports_per_thread[thread_index]++;                       \
+	a->busy_##n##_ports++;                                                \
+	*addr = a->addr;                                                      \
+	*port = clib_host_to_net_u16 (portnum);                               \
+	return 0;                                                             \
+      }
+	  break;
+	  foreach_nat_protocol
+#undef _
+	    default : nat_elog_info (sm, "unknown protocol");
+	  return 1;
+	}
+    }
+
+  /* Totally out of translations to use... */
+  nat_ipfix_logging_addresses_exhausted (thread_index, 0);
+  return 1;
+}
+
+static snat_session_t *
+create_session_for_static_mapping_ed (
+  snat_main_t *sm, vlib_buffer_t *b, ip4_address_t i2o_addr, u16 i2o_port,
+  u32 i2o_fib_index, ip4_address_t o2i_addr, u16 o2i_port, u32 o2i_fib_index,
+  nat_protocol_t nat_proto, vlib_node_runtime_t *node, u32 rx_fib_index,
+  u32 thread_index, twice_nat_type_t twice_nat, lb_nat_type_t lb_nat, f64 now,
+  snat_static_mapping_t *mapping)
+{
+  snat_session_t *s;
+  ip4_header_t *ip;
+  udp_header_t *udp;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+
+  if (PREDICT_FALSE
+      (nat44_ed_maximum_sessions_exceeded (sm, rx_fib_index, thread_index)))
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_elog_notice (sm, "maximum sessions exceeded");
+      return 0;
+    }
+
+  s = nat_ed_session_alloc (sm, thread_index, now, nat_proto);
+  if (!s)
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_elog_warn (sm, "create NAT session failed");
+      return 0;
+    }
+
+  ip = vlib_buffer_get_current (b);
+  udp = ip4_next_header (ip);
+
+  s->ext_host_addr.as_u32 = ip->src_address.as_u32;
+  s->ext_host_port = nat_proto == NAT_PROTOCOL_ICMP ? 0 : udp->src_port;
+  s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
+  if (lb_nat)
+    s->flags |= SNAT_SESSION_FLAG_LOAD_BALANCING;
+  if (lb_nat == AFFINITY_LB_NAT)
+    s->flags |= SNAT_SESSION_FLAG_AFFINITY;
+  s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
+  s->out2in.addr = o2i_addr;
+  s->out2in.port = o2i_port;
+  s->out2in.fib_index = o2i_fib_index;
+  s->in2out.addr = i2o_addr;
+  s->in2out.port = i2o_port;
+  s->in2out.fib_index = i2o_fib_index;
+  s->nat_proto = nat_proto;
+
+  if (NAT_PROTOCOL_ICMP == nat_proto)
+    {
+      nat_6t_o2i_flow_init (sm, thread_index, s, s->ext_host_addr, o2i_port,
+			    o2i_addr, o2i_port, o2i_fib_index, ip->protocol);
+      nat_6t_flow_icmp_id_rewrite_set (&s->o2i, i2o_port);
+    }
+  else
+    {
+      nat_6t_o2i_flow_init (sm, thread_index, s, s->ext_host_addr,
+			    s->ext_host_port, o2i_addr, o2i_port,
+			    o2i_fib_index, ip->protocol);
+      nat_6t_flow_dport_rewrite_set (&s->o2i, i2o_port);
+    }
+  nat_6t_flow_daddr_rewrite_set (&s->o2i, i2o_addr.as_u32);
+  nat_6t_flow_txfib_rewrite_set (&s->o2i, i2o_fib_index);
+
+  if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 1))
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_HASH_ADD_FAILED];
+      nat_ed_session_delete (sm, s, thread_index, 1);
+      nat_elog_warn (sm, "out2in flow hash add failed");
+      return 0;
+    }
+
+  if (twice_nat == TWICE_NAT || (twice_nat == TWICE_NAT_SELF &&
+				 ip->src_address.as_u32 == i2o_addr.as_u32))
+    {
+      int rc = 0;
+      snat_address_t *filter = 0;
+
+      // if exact address is specified use this address
+      if (is_exact_address (mapping))
+	{
+	  snat_address_t *ap;
+	  vec_foreach (ap, sm->twice_nat_addresses)
+	  {
+	    if (mapping->pool_addr.as_u32 == ap->addr.as_u32)
+	      {
+		filter = ap;
+		break;
+	      }
+	  }
+	}
+
+      if (filter)
+	{
+	  rc = nat_alloc_addr_and_port_exact (filter,
+					      thread_index,
+					      nat_proto,
+					      &s->ext_host_nat_addr,
+					      &s->ext_host_nat_port,
+					      sm->port_per_thread,
+					      tsm->snat_thread_index);
+	  s->flags |= SNAT_SESSION_FLAG_EXACT_ADDRESS;
+	}
+      else
+	{
+	  rc = nat44_ed_alloc_outside_addr_and_port (
+	    sm->twice_nat_addresses, 0, thread_index, nat_proto,
+	    &s->ext_host_nat_addr, &s->ext_host_nat_port, sm->port_per_thread,
+	    tsm->snat_thread_index);
+	}
+
+      if (rc)
+	{
+	  b->error = node->errors[NAT_OUT2IN_ED_ERROR_OUT_OF_PORTS];
+	  if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 0))
+	    {
+	      nat_elog_warn (sm, "out2in flow hash del failed");
+	    }
+	  snat_free_outside_address_and_port (
+	    sm->twice_nat_addresses, thread_index, &s->ext_host_nat_addr,
+	    s->ext_host_nat_port, s->nat_proto);
+	  nat_ed_session_delete (sm, s, thread_index, 1);
+	  return 0;
+	}
+
+      s->flags |= SNAT_SESSION_FLAG_TWICE_NAT;
+
+      nat_6t_flow_saddr_rewrite_set (&s->o2i, s->ext_host_nat_addr.as_u32);
+      if (NAT_PROTOCOL_ICMP == nat_proto)
+	{
+	  nat_6t_flow_icmp_id_rewrite_set (&s->o2i, s->ext_host_nat_port);
+	}
+      else
+	{
+	  nat_6t_flow_sport_rewrite_set (&s->o2i, s->ext_host_nat_port);
+	}
+
+      nat_6t_l3_l4_csum_calc (&s->o2i);
+
+      nat_6t_i2o_flow_init (sm, thread_index, s, i2o_addr, i2o_port,
+			    s->ext_host_nat_addr, s->ext_host_nat_port,
+			    i2o_fib_index, ip->protocol);
+      nat_6t_flow_daddr_rewrite_set (&s->i2o, s->ext_host_addr.as_u32);
+      if (NAT_PROTOCOL_ICMP == nat_proto)
+	{
+	  nat_6t_flow_icmp_id_rewrite_set (&s->i2o, s->ext_host_port);
+	}
+      else
+	{
+	  nat_6t_flow_dport_rewrite_set (&s->i2o, s->ext_host_port);
+	}
+    }
+  else
+    {
+      if (NAT_PROTOCOL_ICMP == nat_proto)
+	{
+	  nat_6t_i2o_flow_init (sm, thread_index, s, i2o_addr, i2o_port,
+				s->ext_host_addr, i2o_port, i2o_fib_index,
+				ip->protocol);
+	}
+      else
+	{
+	  nat_6t_i2o_flow_init (sm, thread_index, s, i2o_addr, i2o_port,
+				s->ext_host_addr, s->ext_host_port,
+				i2o_fib_index, ip->protocol);
+	}
+    }
+
+  nat_6t_flow_saddr_rewrite_set (&s->i2o, o2i_addr.as_u32);
+  if (NAT_PROTOCOL_ICMP == nat_proto)
+    {
+      nat_6t_flow_icmp_id_rewrite_set (&s->i2o, o2i_port);
+    }
+  else
+    {
+      nat_6t_flow_sport_rewrite_set (&s->i2o, o2i_port);
+    }
+
+  if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 1))
+    {
+      nat_elog_notice (sm, "in2out flow hash add failed");
+      if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 0))
+	{
+	  nat_elog_warn (sm, "out2in flow hash del failed");
+	}
+      nat_ed_session_delete (sm, s, thread_index, 1);
+      return 0;
+    }
+
+  nat_ipfix_logging_nat44_ses_create (thread_index,
+				      s->in2out.addr.as_u32,
+				      s->out2in.addr.as_u32,
+				      s->nat_proto,
+				      s->in2out.port,
+				      s->out2in.port, s->in2out.fib_index);
+
+  nat_syslog_nat44_sadd (0, s->in2out.fib_index, &s->in2out.addr,
+			 s->in2out.port, &s->ext_host_nat_addr,
+			 s->ext_host_nat_port, &s->out2in.addr, s->out2in.port,
+			 &s->ext_host_addr, s->ext_host_port, s->nat_proto,
+			 is_twice_nat_session (s));
+
+  per_vrf_sessions_register_session (s, thread_index);
+
+  return s;
+}
+
+static void
+create_bypass_for_fwd (snat_main_t *sm, vlib_buffer_t *b, snat_session_t *s,
+		       ip4_header_t *ip, u32 rx_fib_index, u32 thread_index)
+{
+  clib_bihash_kv_16_8_t kv, value;
+  udp_header_t *udp;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  vlib_main_t *vm = vlib_get_main ();
+  f64 now = vlib_time_now (vm);
+  u16 lookup_sport, lookup_dport;
+  u8 lookup_protocol;
+  ip4_address_t lookup_saddr, lookup_daddr;
+
+  if (ip->protocol == IP_PROTOCOL_ICMP)
+    {
+      if (nat_get_icmp_session_lookup_values (b, ip, &lookup_saddr,
+					      &lookup_sport, &lookup_daddr,
+					      &lookup_dport, &lookup_protocol))
+	return;
+    }
+  else
+    {
+      if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
+	{
+	  udp = ip4_next_header (ip);
+	  lookup_sport = udp->dst_port;
+	  lookup_dport = udp->src_port;
+	}
+      else
+	{
+	  lookup_sport = 0;
+	  lookup_dport = 0;
+	}
+      lookup_saddr.as_u32 = ip->dst_address.as_u32;
+      lookup_daddr.as_u32 = ip->src_address.as_u32;
+      lookup_protocol = ip->protocol;
+    }
+
+  init_ed_k (&kv, lookup_saddr, lookup_sport, lookup_daddr, lookup_dport,
+	     rx_fib_index, lookup_protocol);
+
+  if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
+    {
+      ASSERT (thread_index == ed_value_get_thread_index (&value));
+      s =
+	pool_elt_at_index (tsm->sessions,
+			   ed_value_get_session_index (&value));
+    }
+  else if (ip->protocol == IP_PROTOCOL_ICMP &&
+	   icmp_type_is_error_message
+	   (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags))
+    {
+      return;
+    }
+  else
+    {
+      u32 proto;
+
+      if (PREDICT_FALSE
+	  (nat44_ed_maximum_sessions_exceeded
+	   (sm, rx_fib_index, thread_index)))
+	return;
+
+      s = nat_ed_session_alloc (sm, thread_index, now, ip->protocol);
+      if (!s)
+	{
+	  nat_elog_warn (sm, "create NAT session failed");
+	  return;
+	}
+
+      proto = ip_proto_to_nat_proto (ip->protocol);
+
+      s->ext_host_addr = ip->src_address;
+      s->ext_host_port = lookup_dport;
+      s->flags |= SNAT_SESSION_FLAG_FWD_BYPASS;
+      s->out2in.addr = ip->dst_address;
+      s->out2in.port = lookup_sport;
+      s->nat_proto = proto;
+      if (proto == NAT_PROTOCOL_OTHER)
+	{
+	  s->flags |= SNAT_SESSION_FLAG_UNKNOWN_PROTO;
+	  s->out2in.port = ip->protocol;
+	}
+      s->out2in.fib_index = rx_fib_index;
+      s->in2out.addr = s->out2in.addr;
+      s->in2out.port = s->out2in.port;
+      s->in2out.fib_index = s->out2in.fib_index;
+
+      nat_6t_i2o_flow_init (sm, thread_index, s, ip->dst_address, lookup_sport,
+			    ip->src_address, lookup_dport, rx_fib_index,
+			    ip->protocol);
+      nat_6t_flow_txfib_rewrite_set (&s->i2o, rx_fib_index);
+      if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 1))
+	{
+	  nat_elog_notice (sm, "in2out flow add failed");
+	  nat_ed_session_delete (sm, s, thread_index, 1);
+	  return;
+	}
+
+      per_vrf_sessions_register_session (s, thread_index);
+    }
+
+  if (ip->protocol == IP_PROTOCOL_TCP)
+    {
+      tcp_header_t *tcp = ip4_next_header (ip);
+      nat44_set_tcp_session_state_o2i (sm, now, s, tcp->flags,
+				       tcp->ack_number, tcp->seq_number,
+				       thread_index);
+    }
+
+  /* Accounting */
+  nat44_session_update_counters (s, now, 0, thread_index);
+  /* Per-user LRU list maintenance */
+  nat44_session_update_lru (sm, s, thread_index);
+}
+
+static snat_session_t *
+nat44_ed_out2in_slowpath_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;
+  snat_static_mapping_t *m;
+  snat_session_t *s;
+
+  if (PREDICT_FALSE (
+	nat44_ed_maximum_sessions_exceeded (sm, rx_fib_index, thread_index)))
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_elog_notice (sm, "maximum sessions exceeded");
+      return 0;
+    }
+
+  init_nat_k (&kv, ip->dst_address, 0, 0, 0);
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
+      return 0;
+    }
+
+  m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  /* Create a new session */
+  s = nat_ed_session_alloc (sm, thread_index, now, ip->protocol);
+  if (!s)
+    {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_elog_warn (sm, "create NAT session failed");
+      return 0;
+    }
+
+  s->ext_host_addr.as_u32 = ip->src_address.as_u32;
+  s->flags |= SNAT_SESSION_FLAG_UNKNOWN_PROTO;
+  s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
+  s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
+  s->out2in.addr.as_u32 = ip->dst_address.as_u32;
+  s->out2in.fib_index = rx_fib_index;
+  s->in2out.addr.as_u32 = m->local_addr.as_u32;
+  s->in2out.fib_index = m->fib_index;
+  s->in2out.port = s->out2in.port = ip->protocol;
+
+  nat_6t_o2i_flow_init (sm, thread_index, s, ip->dst_address, 0,
+			ip->src_address, 0, m->fib_index, ip->protocol);
+  nat_6t_flow_saddr_rewrite_set (&s->i2o, ip->dst_address.as_u32);
+  if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 1))
+    {
+      nat_elog_notice (sm, "in2out key add failed");
+      nat_ed_session_delete (sm, s, thread_index, 1);
+      return NULL;
+    }
+
+  nat_6t_o2i_flow_init (sm, thread_index, s, ip->src_address, 0,
+			ip->dst_address, 0, rx_fib_index, ip->protocol);
+  nat_6t_flow_daddr_rewrite_set (&s->o2i, m->local_addr.as_u32);
+  nat_6t_flow_txfib_rewrite_set (&s->o2i, m->fib_index);
+  if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 1))
+    {
+      nat_elog_notice (sm, "out2in flow hash add failed");
+      nat_ed_session_delete (sm, s, thread_index, 1);
+      return NULL;
+    }
+
+  per_vrf_sessions_register_session (s, thread_index);
+
+  /* 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 s;
+}
+
+static inline uword
+nat44_ed_out2in_fast_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame,
+					  int is_multi_worker)
+{
+  u32 n_left_from, *from;
+  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];
+
+  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 > 0)
+    {
+      vlib_buffer_t *b0;
+      u32 sw_if_index0, rx_fib_index0;
+      nat_protocol_t proto0;
+      ip4_header_t *ip0;
+      snat_session_t *s0 = 0;
+      clib_bihash_kv_16_8_t kv0, value0;
+      nat_translation_error_e translation_error = NAT_ED_TRNSL_ERR_SUCCESS;
+      nat_6t_flow_t *f = 0;
+      ip4_address_t lookup_saddr, lookup_daddr;
+      u16 lookup_sport, lookup_dport;
+      u8 lookup_protocol;
+      int lookup_skipped = 0;
+
+      b0 = *b;
+      b++;
+
+      lookup_sport = vnet_buffer (b0)->ip.reass.l4_src_port;
+      lookup_dport = vnet_buffer (b0)->ip.reass.l4_dst_port;
+
+      /* Prefetch next iteration. */
+      if (PREDICT_TRUE (n_left_from >= 2))
+	{
+	  vlib_buffer_t *p2;
+
+	  p2 = *b;
+
+	  vlib_prefetch_buffer_header (p2, LOAD);
+
+	  CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, LOAD);
+	}
+
+      next[0] = vnet_buffer2 (b0)->nat.arc_next;
+
+      vnet_buffer (b0)->snat.flags = 0;
+      ip0 = vlib_buffer_get_current (b0);
+
+      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);
+	  next[0] = NAT_NEXT_ICMP_ERROR;
+	  goto trace0;
+	}
+
+      proto0 = ip_proto_to_nat_proto (ip0->protocol);
+
+      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
+	{
+	  if (vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
+		ICMP4_echo_request &&
+	      vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
+		ICMP4_echo_reply &&
+	      !icmp_type_is_error_message (
+		vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags))
+	    {
+	      b0->error = node->errors[NAT_OUT2IN_ED_ERROR_BAD_ICMP_TYPE];
+	      next[0] = NAT_NEXT_DROP;
+	      goto trace0;
+	    }
+	  int err = nat_get_icmp_session_lookup_values (
+	    b0, ip0, &lookup_saddr, &lookup_sport, &lookup_daddr,
+	    &lookup_dport, &lookup_protocol);
+	  if (err != 0)
+	    {
+	      b0->error = node->errors[err];
+	      next[0] = NAT_NEXT_DROP;
+	      goto trace0;
+	    }
+	}
+      else
+	{
+	  lookup_saddr.as_u32 = ip0->src_address.as_u32;
+	  lookup_daddr.as_u32 = ip0->dst_address.as_u32;
+	  lookup_protocol = ip0->protocol;
+	}
+
+      /* there might be a stashed index in vnet_buffer2 from handoff or
+       * classify node, see if it can be used */
+      if (!pool_is_free_index (tsm->sessions,
+			       vnet_buffer2 (b0)->nat.cached_session_index))
+	{
+	  s0 = pool_elt_at_index (tsm->sessions,
+				  vnet_buffer2 (b0)->nat.cached_session_index);
+	  if (PREDICT_TRUE (
+		nat_6t_flow_match (&s0->o2i, b0, lookup_saddr, lookup_sport,
+				   lookup_daddr, lookup_dport, lookup_protocol,
+				   rx_fib_index0) ||
+		(s0->flags & SNAT_SESSION_FLAG_TWICE_NAT &&
+		 nat_6t_flow_match (&s0->i2o, b0, lookup_saddr, lookup_sport,
+				    lookup_daddr, lookup_dport,
+				    lookup_protocol, rx_fib_index0))))
+	    {
+	      /* yes, this is the droid we're looking for */
+	      lookup_skipped = 1;
+	      goto skip_lookup;
+	    }
+	  s0 = NULL;
+	}
+
+      init_ed_k (&kv0, lookup_saddr, lookup_sport, lookup_daddr, lookup_dport,
+		 rx_fib_index0, lookup_protocol);
+
+      // lookup flow
+      if (clib_bihash_search_16_8 (&sm->flow_hash, &kv0, &value0))
+	{
+	  // flow does not exist go slow path
+	  next[0] = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+	  goto trace0;
+	}
+      ASSERT (thread_index == ed_value_get_thread_index (&value0));
+      s0 =
+	pool_elt_at_index (tsm->sessions,
+			   ed_value_get_session_index (&value0));
+    skip_lookup:
+
+      if (PREDICT_FALSE (per_vrf_sessions_is_expired (s0, thread_index)))
+	{
+	  // session is closed, go slow path
+	  nat_free_session_data (sm, s0, thread_index, 0);
+	  nat_ed_session_delete (sm, s0, thread_index, 1);
+	  next[0] = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+	  goto trace0;
+	}
+
+      if (s0->tcp_closed_timestamp)
+	{
+	  if (now >= s0->tcp_closed_timestamp)
+	    {
+	      // session is closed, go slow path, freed in slow path
+	      next[0] = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+	    }
+	  else
+	    {
+	      // session in transitory timeout, drop
+	      b0->error = node->errors[NAT_OUT2IN_ED_ERROR_TCP_CLOSED];
+	      next[0] = NAT_NEXT_DROP;
+	    }
+	  goto trace0;
+	}
+
+      // drop if session expired
+      u64 sess_timeout_time;
+      sess_timeout_time =
+	s0->last_heard + (f64) nat44_session_get_timeout (sm, s0);
+      if (now >= sess_timeout_time)
+	{
+	  // session is closed, go slow path
+	  nat_free_session_data (sm, s0, thread_index, 0);
+	  nat_ed_session_delete (sm, s0, thread_index, 1);
+	  next[0] = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+	  goto trace0;
+	}
+
+      if (nat_6t_flow_match (&s0->o2i, b0, lookup_saddr, lookup_sport,
+			     lookup_daddr, lookup_dport, lookup_protocol,
+			     rx_fib_index0))
+	{
+	  f = &s0->o2i;
+	}
+      else if (s0->flags & SNAT_SESSION_FLAG_TWICE_NAT &&
+	       nat_6t_flow_match (&s0->i2o, b0, lookup_saddr, lookup_sport,
+				  lookup_daddr, lookup_dport, lookup_protocol,
+				  rx_fib_index0))
+	{
+	  f = &s0->i2o;
+	}
+      else
+	{
+	  /*
+	   * Send DHCP packets to the ipv4 stack, or we won't
+	   * be able to use dhcp client on the outside interface
+	   */
+	  if (PREDICT_FALSE (
+		proto0 == NAT_PROTOCOL_UDP &&
+		(vnet_buffer (b0)->ip.reass.l4_dst_port ==
+		 clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_client))))
+	    {
+	      goto trace0;
+	    }
+
+	  if (!sm->forwarding_enabled)
+	    {
+	      b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
+	      next[0] = NAT_NEXT_DROP;
+	      goto trace0;
+	    }
+	  else
+	    {
+	      if (nat_6t_flow_match (&s0->i2o, b0, lookup_saddr, lookup_sport,
+				     lookup_daddr, lookup_dport,
+				     lookup_protocol, rx_fib_index0))
+		{
+		  f = &s0->i2o;
+		}
+	      else
+		{
+		  // FIXME TODO bypass ???
+		  //  create_bypass_for_fwd (sm, b0, s0, ip0, rx_fib_index0,
+		  //                       thread_index);
+		  translation_error = NAT_ED_TRNSL_ERR_FLOW_MISMATCH;
+		  nat_free_session_data (sm, s0, thread_index, 0);
+		  nat_ed_session_delete (sm, s0, thread_index, 1);
+		  next[0] = NAT_NEXT_DROP;
+		  goto trace0;
+		}
+	    }
+	}
+
+      if (NAT_ED_TRNSL_ERR_SUCCESS !=
+	  (translation_error = nat_6t_flow_buf_translate (
+	     sm, b0, ip0, f, proto0, 0 /* is_output_feature */)))
+	{
+	  next[0] = NAT_NEXT_DROP;
+	  goto trace0;
+	}
+
+      switch (proto0)
+	{
+	case NAT_PROTOCOL_TCP:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.out2in.tcp,
+					 thread_index, sw_if_index0, 1);
+	  nat44_set_tcp_session_state_o2i (sm, now, s0,
+					   vnet_buffer (b0)->ip.
+					   reass.icmp_type_or_tcp_flags,
+					   vnet_buffer (b0)->ip.
+					   reass.tcp_ack_number,
+					   vnet_buffer (b0)->ip.
+					   reass.tcp_seq_number,
+					   thread_index);
+	  break;
+	case NAT_PROTOCOL_UDP:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.out2in.udp,
+					 thread_index, sw_if_index0, 1);
+	  break;
+	case NAT_PROTOCOL_ICMP:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.out2in.icmp,
+					 thread_index, sw_if_index0, 1);
+	  break;
+	case NAT_PROTOCOL_OTHER:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.out2in.other,
+					 thread_index, sw_if_index0, 1);
+	  break;
+	}
+
+      /* 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)))
+	{
+	  nat44_ed_out2in_trace_t *t =
+	    vlib_add_trace (vm, node, b0, sizeof (*t));
+	  t->sw_if_index = sw_if_index0;
+	  t->next_index = next[0];
+	  t->is_slow_path = 0;
+	  t->translation_error = translation_error;
+	  clib_memcpy (&t->search_key, &kv0, sizeof (t->search_key));
+	  t->lookup_skipped = lookup_skipped;
+
+	  if (s0)
+	    {
+	      t->session_index = s0 - tsm->sessions;
+	      clib_memcpy (&t->i2of, &s0->i2o, sizeof (t->i2of));
+	      clib_memcpy (&t->o2if, &s0->o2i, sizeof (t->o2if));
+	      t->translation_via_i2of = (&s0->i2o == f);
+	    }
+	  else
+	    {
+	      t->session_index = ~0;
+	    }
+	}
+
+      if (next[0] == NAT_NEXT_DROP)
+	{
+	  vlib_increment_simple_counter (&sm->counters.fastpath.out2in.drops,
+					 thread_index, sw_if_index0, 1);
+	}
+
+      n_left_from--;
+      next++;
+    }
+
+  vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
+			       frame->n_vectors);
+  return frame->n_vectors;
+}
+
+static inline uword
+nat44_ed_out2in_slow_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame)
+{
+  u32 n_left_from, *from;
+  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];
+  snat_static_mapping_t *m;
+
+  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 > 0)
+    {
+      vlib_buffer_t *b0;
+      u32 sw_if_index0, rx_fib_index0;
+      nat_protocol_t proto0;
+      ip4_header_t *ip0;
+      udp_header_t *udp0;
+      icmp46_header_t *icmp0;
+      snat_session_t *s0 = 0;
+      clib_bihash_kv_16_8_t kv0, value0;
+      lb_nat_type_t lb_nat0;
+      twice_nat_type_t twice_nat0;
+      u8 identity_nat0;
+      ip4_address_t sm_addr;
+      u16 sm_port;
+      u32 sm_fib_index;
+      nat_translation_error_e translation_error = NAT_ED_TRNSL_ERR_SUCCESS;
+
+      b0 = *b;
+      next[0] = vnet_buffer2 (b0)->nat.arc_next;
+
+      vnet_buffer (b0)->snat.flags = 0;
+      ip0 = vlib_buffer_get_current (b0);
+
+      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);
+	  next[0] = NAT_NEXT_ICMP_ERROR;
+	  goto trace0;
+	}
+
+      udp0 = ip4_next_header (ip0);
+      icmp0 = (icmp46_header_t *) udp0;
+      proto0 = ip_proto_to_nat_proto (ip0->protocol);
+
+      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_OTHER))
+	{
+	  s0 = nat44_ed_out2in_slowpath_unknown_proto (
+	    sm, b0, ip0, rx_fib_index0, thread_index, now, vm, node);
+	  if (!sm->forwarding_enabled)
+	    {
+	      if (!s0)
+		next[0] = NAT_NEXT_DROP;
+	    }
+	  if (NAT_NEXT_DROP != next[0] &&
+	      NAT_ED_TRNSL_ERR_SUCCESS !=
+		(translation_error = nat_6t_flow_buf_translate (
+		   sm, b0, ip0, &s0->o2i, proto0, 0 /* is_output_feature */)))
+	    {
+	      goto trace0;
+	    }
+
+	  vlib_increment_simple_counter (&sm->counters.slowpath.out2in.other,
+					 thread_index, sw_if_index0, 1);
+	  goto trace0;
+	}
+
+      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
+	{
+	  next[0] = icmp_out2in_ed_slow_path
+	    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+	     next[0], now, thread_index, &s0);
+
+	  if (NAT_NEXT_DROP != next[0] && s0 &&
+	      NAT_ED_TRNSL_ERR_SUCCESS !=
+		(translation_error = nat_6t_flow_buf_translate (
+		   sm, b0, ip0, &s0->o2i, proto0, 0 /* is_output_feature */)))
+	    {
+	      goto trace0;
+	    }
+
+	  vlib_increment_simple_counter (&sm->counters.slowpath.out2in.icmp,
+					 thread_index, sw_if_index0, 1);
+	  goto trace0;
+	}
+
+      init_ed_k (&kv0, ip0->src_address,
+		 vnet_buffer (b0)->ip.reass.l4_src_port, ip0->dst_address,
+		 vnet_buffer (b0)->ip.reass.l4_dst_port, rx_fib_index0,
+		 ip0->protocol);
+
+      s0 = NULL;
+      if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv0, &value0))
+	{
+	  ASSERT (thread_index == ed_value_get_thread_index (&value0));
+	  s0 =
+	    pool_elt_at_index (tsm->sessions,
+			       ed_value_get_session_index (&value0));
+
+	  if (s0->tcp_closed_timestamp && now >= s0->tcp_closed_timestamp)
+	    {
+	      nat_free_session_data (sm, s0, thread_index, 0);
+	      nat_ed_session_delete (sm, s0, thread_index, 1);
+	      s0 = NULL;
+	    }
+	}
+
+      if (!s0)
+	{
+	  /* Try to match static mapping by external address and port,
+	     destination address and port in packet */
+
+	  if (snat_static_mapping_match
+	      (sm, ip0->dst_address,
+	       vnet_buffer (b0)->ip.reass.l4_dst_port, rx_fib_index0,
+	       proto0, &sm_addr, &sm_port, &sm_fib_index, 1, 0,
+	       &twice_nat0, &lb_nat0, &ip0->src_address, &identity_nat0, &m))
+	    {
+	      /*
+	       * Send DHCP packets to the ipv4 stack, or we won't
+	       * be able to use dhcp client on the outside interface
+	       */
+	      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_UDP
+				 && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
+				     clib_host_to_net_u16
+				     (UDP_DST_PORT_dhcp_to_client))))
+		{
+		  goto trace0;
+		}
+
+	      if (!sm->forwarding_enabled)
+		{
+		  b0->error =
+		    node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
+		  next[0] = NAT_NEXT_DROP;
+		}
+	      else
+		{
+		  if (next_src_nat
+		      (sm, ip0, vnet_buffer (b0)->ip.reass.l4_src_port,
+		       vnet_buffer (b0)->ip.reass.l4_dst_port,
+		       thread_index, rx_fib_index0))
+		    {
+		      next[0] = NAT_NEXT_IN2OUT_ED_FAST_PATH;
+		    }
+		  else
+		    {
+		      create_bypass_for_fwd (sm, b0, s0, ip0, rx_fib_index0,
+					     thread_index);
+		    }
+		}
+	      goto trace0;
+	    }
+
+	  if (PREDICT_FALSE (identity_nat0))
+	    goto trace0;
+
+	  if ((proto0 == NAT_PROTOCOL_TCP)
+	      && !tcp_flags_is_init (vnet_buffer (b0)->ip.
+				     reass.icmp_type_or_tcp_flags))
+	    {
+	      b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+	      next[0] = NAT_NEXT_DROP;
+	      goto trace0;
+	    }
+
+	  /* Create session initiated by host from external network */
+	  s0 = create_session_for_static_mapping_ed (sm, b0,
+						     sm_addr, sm_port,
+						     sm_fib_index,
+						     ip0->dst_address,
+						     vnet_buffer (b0)->
+						     ip.reass.l4_dst_port,
+						     rx_fib_index0, proto0,
+						     node, rx_fib_index0,
+						     thread_index, twice_nat0,
+						     lb_nat0, now, m);
+	  if (!s0)
+	    {
+	      next[0] = NAT_NEXT_DROP;
+	      goto trace0;
+	    }
+	}
+
+      if (NAT_ED_TRNSL_ERR_SUCCESS !=
+	  (translation_error = nat_6t_flow_buf_translate (
+	     sm, b0, ip0, &s0->o2i, proto0, 0 /* is_output_feature */)))
+	{
+	  next[0] = NAT_NEXT_DROP;
+	  goto trace0;
+	}
+
+      if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
+	{
+	  vlib_increment_simple_counter (&sm->counters.slowpath.out2in.tcp,
+					 thread_index, sw_if_index0, 1);
+	  nat44_set_tcp_session_state_o2i (sm, now, s0,
+					   vnet_buffer (b0)->ip.
+					   reass.icmp_type_or_tcp_flags,
+					   vnet_buffer (b0)->ip.
+					   reass.tcp_ack_number,
+					   vnet_buffer (b0)->ip.
+					   reass.tcp_seq_number,
+					   thread_index);
+	}
+      else
+	{
+	  vlib_increment_simple_counter (&sm->counters.slowpath.out2in.udp,
+					 thread_index, sw_if_index0, 1);
+	}
+
+      /* 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)))
+	{
+	  nat44_ed_out2in_trace_t *t =
+	    vlib_add_trace (vm, node, b0, sizeof (*t));
+	  t->sw_if_index = sw_if_index0;
+	  t->next_index = next[0];
+	  t->is_slow_path = 1;
+	  t->translation_error = translation_error;
+	  clib_memcpy (&t->search_key, &kv0, sizeof (t->search_key));
+
+	  if (s0)
+	    {
+	      t->session_index = s0 - tsm->sessions;
+	      clib_memcpy (&t->i2of, &s0->i2o, sizeof (t->i2of));
+	      clib_memcpy (&t->o2if, &s0->o2i, sizeof (t->o2if));
+	    }
+	  else
+	    {
+	      t->session_index = ~0;
+	    }
+	}
+
+      if (next[0] == NAT_NEXT_DROP)
+	{
+	  vlib_increment_simple_counter (&sm->counters.slowpath.out2in.drops,
+					 thread_index, sw_if_index0, 1);
+	}
+
+      n_left_from--;
+      next++;
+      b++;
+    }
+
+  vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
+			       frame->n_vectors);
+
+  return frame->n_vectors;
+}
+
+VLIB_NODE_FN (nat44_ed_out2in_node) (vlib_main_t * vm,
+				     vlib_node_runtime_t * node,
+				     vlib_frame_t * frame)
+{
+  if (snat_main.num_workers > 1)
+    {
+      return nat44_ed_out2in_fast_path_node_fn_inline (vm, node, frame, 1);
+    }
+  else
+    {
+      return nat44_ed_out2in_fast_path_node_fn_inline (vm, node, frame, 0);
+    }
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat44_ed_out2in_node) = {
+  .name = "nat44-ed-out2in",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat44_ed_out2in_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN(nat_out2in_ed_error_strings),
+  .error_strings = nat_out2in_ed_error_strings,
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+};
+/* *INDENT-ON* */
+
+VLIB_NODE_FN (nat44_ed_out2in_slowpath_node) (vlib_main_t * vm,
+					      vlib_node_runtime_t * node,
+					      vlib_frame_t * frame)
+{
+  return nat44_ed_out2in_slow_path_node_fn_inline (vm, node, frame);
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat44_ed_out2in_slowpath_node) = {
+  .name = "nat44-ed-out2in-slowpath",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat44_ed_out2in_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN(nat_out2in_ed_error_strings),
+  .error_strings = nat_out2in_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, "out2in next_index %d arc_next_index %d", t->next_index,
+		 t->arc_next_index);
+}
+
+VLIB_NODE_FN (nat_pre_out2in_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_OUT2IN_ED_FAST_PATH);
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat_pre_out2in_node) = {
+  .name = "nat-pre-out2in",
+  .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:
+ */