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, 1579 insertions, 0 deletions

diff --git a/src/plugins/nat/nat44-ed/nat44_ed_in2out.c b/src/plugins/nat/nat44-ed/nat44_ed_in2out.c
new file mode 100644
index 00000000000..784dea0faf6
--- /dev/null
+++ b/src/plugins/nat/nat44-ed/nat44_ed_in2out.c
@@ -0,0 +1,1579 @@
+/*
+ * Copyright (c) 2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * @file
+ * @brief NAT44 endpoint-dependent inside to outside network translation
+ */
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/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/nat_inlines.h>
+#include <nat/lib/ipfix_logging.h>
+
+#include <nat/nat44-ed/nat44_ed.h>
+#include <nat/nat44-ed/nat44_ed_inlines.h>
+
+/* number of attempts to get a port for ED overloading algorithm, if rolling
+ * a dice this many times doesn't produce a free port, it's treated
+ * as if there were no free ports available to conserve resources */
+#define ED_PORT_ALLOC_ATTEMPTS (10)
+
+static char *nat_in2out_ed_error_strings[] = {
+#define _(sym,string) string,
+  foreach_nat_in2out_ed_error
+#undef _
+};
+
+typedef struct
+{
+  u32 sw_if_index;
+  u32 next_index;
+  u32 session_index;
+  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;
+} nat_in2out_ed_trace_t;
+
+static u8 *
+format_nat_in2out_ed_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  nat_in2out_ed_trace_t *t = va_arg (*args, nat_in2out_ed_trace_t *);
+  char *tag;
+
+  tag =
+    t->is_slow_path ? "NAT44_IN2OUT_ED_SLOW_PATH" :
+    "NAT44_IN2OUT_ED_FAST_PATH";
+
+  s = format (s, "%s: sw_if_index %d, next index %d, session %d", tag,
+	      t->sw_if_index, t->next_index, t->session_index);
+  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;
+}
+
+/**
+ * @brief Check if packet should be translated
+ *
+ * Packets aimed at outside interface and external address with active session
+ * should be translated.
+ *
+ * @param sm            NAT main
+ * @param rt            NAT runtime data
+ * @param sw_if_index0  index of the inside interface
+ * @param ip0           IPv4 header
+ * @param proto0        NAT protocol
+ * @param rx_fib_index0 RX FIB index
+ *
+ * @returns 0 if packet should be translated otherwise 1
+ */
+static inline int
+snat_not_translate_fast (snat_main_t *sm, vlib_node_runtime_t *node,
+			 u32 sw_if_index0, ip4_header_t *ip0, u32 proto0,
+			 u32 rx_fib_index0)
+{
+  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
+  nat_outside_fib_t *outside_fib;
+  fib_prefix_t pfx = {
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_len = 32,
+    .fp_addr = {
+		.ip4.as_u32 = ip0->dst_address.as_u32,
+		}
+    ,
+  };
+
+  /* Don't NAT packet aimed at the intfc address */
+  if (PREDICT_FALSE (
+	is_interface_addr (sm, node, sw_if_index0, ip0->dst_address.as_u32)))
+    return 1;
+
+  fei = fib_table_lookup (rx_fib_index0, &pfx);
+  if (FIB_NODE_INDEX_INVALID != fei)
+    {
+      u32 sw_if_index = fib_entry_get_resolving_interface (fei);
+      if (sw_if_index == ~0)
+	{
+	  vec_foreach (outside_fib, sm->outside_fibs)
+	    {
+	      fei = fib_table_lookup (outside_fib->fib_index, &pfx);
+	      if (FIB_NODE_INDEX_INVALID != fei)
+		{
+		  sw_if_index = fib_entry_get_resolving_interface (fei);
+		  if (sw_if_index != ~0)
+		    break;
+		}
+	    }
+	}
+      if (sw_if_index == ~0)
+	return 1;
+
+      snat_interface_t *i;
+      pool_foreach (i, sm->interfaces)
+	{
+	  /* NAT packet aimed at outside interface */
+	  if ((nat_interface_is_outside (i)) &&
+	      (sw_if_index == i->sw_if_index))
+	    return 0;
+	}
+    }
+
+  return 1;
+}
+
+static int
+nat_ed_alloc_addr_and_port (snat_main_t *sm, u32 rx_fib_index, u32 nat_proto,
+			    u32 thread_index, ip4_address_t r_addr, u16 r_port,
+			    u8 proto, u16 port_per_thread,
+			    u32 snat_thread_index, snat_session_t *s,
+			    ip4_address_t *outside_addr, u16 *outside_port)
+{
+  int i;
+  snat_address_t *a, *ga = 0;
+
+  const u16 port_thread_offset = (port_per_thread * snat_thread_index) + 1024;
+
+  for (i = 0; i < vec_len (sm->addresses); i++)
+    {
+      a = sm->addresses + i;
+      switch (nat_proto)
+	{
+#define _(N, j, n, unused)                                                    \
+  case NAT_PROTOCOL_##N:                                                      \
+    if (a->fib_index == rx_fib_index)                                         \
+      {                                                                       \
+	s->o2i.match.daddr = a->addr;                                         \
+	/* first try port suggested by caller */                              \
+	u16 port = clib_net_to_host_u16 (*outside_port);                      \
+	u16 port_offset = port - port_thread_offset;                          \
+	if (port <= port_thread_offset ||                                     \
+	    port > port_thread_offset + port_per_thread)                      \
+	  {                                                                   \
+	    /* need to pick a different port, suggested port doesn't fit in   \
+	     * this thread's port range */                                    \
+	    port_offset = snat_random_port (0, port_per_thread - 1);          \
+	    port = port_thread_offset + port_offset;                          \
+	  }                                                                   \
+	u16 attempts = ED_PORT_ALLOC_ATTEMPTS;                                \
+	do                                                                    \
+	  {                                                                   \
+	    if (NAT_PROTOCOL_ICMP == nat_proto)                               \
+	      {                                                               \
+		s->o2i.match.sport = clib_host_to_net_u16 (port);             \
+	      }                                                               \
+	    s->o2i.match.dport = clib_host_to_net_u16 (port);                 \
+	    if (0 ==                                                          \
+		nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 2))    \
+	      {                                                               \
+		++a->busy_##n##_port_refcounts[port];                         \
+		a->busy_##n##_ports_per_thread[thread_index]++;               \
+		a->busy_##n##_ports++;                                        \
+		*outside_addr = a->addr;                                      \
+		*outside_port = clib_host_to_net_u16 (port);                  \
+		return 0;                                                     \
+	      }                                                               \
+	    port_offset = snat_random_port (0, port_per_thread - 1);          \
+	    port = port_thread_offset + port_offset;                          \
+	    --attempts;                                                       \
+	  }                                                                   \
+	while (attempts > 0);                                                 \
+      }                                                                       \
+    else if (a->fib_index == ~0)                                              \
+      {                                                                       \
+	ga = a;                                                               \
+      }                                                                       \
+    break;
+
+	  foreach_nat_protocol;
+	default:
+	  nat_elog_info (sm, "unknown protocol");
+	  return 1;
+	}
+    }
+
+  if (ga)
+    {
+      /* fake fib_index to reuse macro */
+      rx_fib_index = ~0;
+      a = ga;
+      switch (nat_proto)
+	{
+	  foreach_nat_protocol;
+	default:
+	  nat_elog_info (sm, "unknown protocol");
+	  return 1;
+	}
+    }
+
+#undef _
+
+  /* Totally out of translations to use... */
+  nat_ipfix_logging_addresses_exhausted (thread_index, 0);
+  return 1;
+}
+
+static_always_inline u32
+nat_outside_fib_index_lookup (snat_main_t * sm, ip4_address_t addr)
+{
+  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
+  nat_outside_fib_t *outside_fib;
+  fib_prefix_t pfx = {
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_len = 32,
+    .fp_addr = {.ip4.as_u32 = addr.as_u32,}
+    ,
+  };
+  // TODO: multiple vrfs none can resolve addr
+  vec_foreach (outside_fib, sm->outside_fibs)
+    {
+      fei = fib_table_lookup (outside_fib->fib_index, &pfx);
+      if (FIB_NODE_INDEX_INVALID != fei)
+        {
+          if (fib_entry_get_resolving_interface (fei) != ~0)
+            {
+              return outside_fib->fib_index;
+            }
+        }
+    }
+  return ~0;
+}
+
+static_always_inline int
+nat44_ed_external_sm_lookup (snat_main_t *sm, ip4_address_t match_addr,
+			     u16 match_port, nat_protocol_t match_protocol,
+			     u32 match_fib_index, ip4_address_t *daddr,
+			     u16 *dport)
+{
+  clib_bihash_kv_8_8_t kv, value;
+  init_nat_k (&kv, match_addr, match_port, match_fib_index, match_protocol);
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    {
+      /* Try address only mapping */
+      init_nat_k (&kv, match_addr, 0, 0, 0);
+      if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv,
+				  &value))
+	return 0;
+    }
+
+  snat_static_mapping_t *m =
+    pool_elt_at_index (sm->static_mappings, value.value);
+  *daddr = m->local_addr;
+  if (dport)
+    {
+      /* Address only mapping doesn't change port */
+      *dport = is_addr_only_static_mapping (m) ? match_port : m->local_port;
+    }
+  return 1;
+}
+
+static u32
+slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
+	      ip4_address_t r_addr, u16 l_port, u16 r_port, u8 proto,
+	      u32 rx_fib_index, snat_session_t **sessionp,
+	      vlib_node_runtime_t *node, u32 next, u32 thread_index, f64 now)
+{
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  ip4_address_t outside_addr;
+  u16 outside_port;
+  u32 outside_fib_index;
+  u8 is_identity_nat;
+
+  u32 nat_proto = ip_proto_to_nat_proto (proto);
+  snat_session_t *s = NULL;
+  lb_nat_type_t lb = 0;
+  ip4_address_t daddr = r_addr;
+  u16 dport = r_port;
+
+  if (PREDICT_TRUE (nat_proto == NAT_PROTOCOL_TCP))
+    {
+      if (PREDICT_FALSE
+	  (!tcp_flags_is_init
+	   (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags)))
+	{
+	  b->error = node->errors[NAT_IN2OUT_ED_ERROR_NON_SYN];
+	  return NAT_NEXT_DROP;
+	}
+    }
+
+  if (PREDICT_FALSE
+      (nat44_ed_maximum_sessions_exceeded (sm, rx_fib_index, thread_index)))
+    {
+      if (!nat_lru_free_one (sm, thread_index, now))
+	{
+	  b->error = node->errors[NAT_IN2OUT_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+	  nat_ipfix_logging_max_sessions (thread_index,
+					  sm->max_translations_per_thread);
+	  nat_elog_notice (sm, "maximum sessions exceeded");
+	  return NAT_NEXT_DROP;
+	}
+    }
+
+  outside_fib_index = sm->outside_fib_index;
+
+  switch (vec_len (sm->outside_fibs))
+    {
+    case 0:
+      outside_fib_index = sm->outside_fib_index;
+      break;
+    case 1:
+      outside_fib_index = sm->outside_fibs[0].fib_index;
+      break;
+    default:
+      outside_fib_index = nat_outside_fib_index_lookup (sm, r_addr);
+      break;
+    }
+
+  ip4_address_t sm_addr;
+  u16 sm_port;
+  u32 sm_fib_index;
+  /* First try to match static mapping by local address and port */
+  int is_sm;
+  if (snat_static_mapping_match (sm, l_addr, l_port, rx_fib_index, nat_proto,
+				 &sm_addr, &sm_port, &sm_fib_index, 0, 0, 0,
+				 &lb, 0, &is_identity_nat, 0))
+    {
+      is_sm = 0;
+    }
+  else
+    {
+      is_sm = 1;
+    }
+
+  if (PREDICT_FALSE (is_sm && is_identity_nat))
+    {
+      *sessionp = NULL;
+      return next;
+    }
+
+  s = nat_ed_session_alloc (sm, thread_index, now, proto);
+  ASSERT (s);
+
+  if (!is_sm)
+    {
+      s->in2out.addr = l_addr;
+      s->in2out.port = l_port;
+      s->nat_proto = nat_proto;
+      s->in2out.fib_index = rx_fib_index;
+      s->out2in.fib_index = outside_fib_index;
+
+      // suggest using local port to allocation function
+      outside_port = l_port;
+
+      // hairpinning?
+      int is_hairpinning = nat44_ed_external_sm_lookup (
+	sm, r_addr, r_port, nat_proto, outside_fib_index, &daddr, &dport);
+      s->flags |= is_hairpinning * SNAT_SESSION_FLAG_HAIRPINNING;
+
+      // destination addr/port updated with real values in
+      // nat_ed_alloc_addr_and_port
+      nat_6t_o2i_flow_init (sm, thread_index, s, daddr, dport, daddr, 0,
+			    s->out2in.fib_index, proto);
+      nat_6t_flow_daddr_rewrite_set (&s->o2i, l_addr.as_u32);
+      if (NAT_PROTOCOL_ICMP == nat_proto)
+	{
+	  nat_6t_flow_icmp_id_rewrite_set (&s->o2i, l_port);
+	}
+      else
+	{
+	  nat_6t_flow_dport_rewrite_set (&s->o2i, l_port);
+	}
+      nat_6t_flow_txfib_rewrite_set (&s->o2i, rx_fib_index);
+
+      if (nat_ed_alloc_addr_and_port (
+	    sm, rx_fib_index, nat_proto, thread_index, daddr, dport, proto,
+	    sm->port_per_thread, tsm->snat_thread_index, s, &outside_addr,
+	    &outside_port))
+	{
+	  nat_elog_notice (sm, "addresses exhausted");
+	  b->error = node->errors[NAT_IN2OUT_ED_ERROR_OUT_OF_PORTS];
+	  nat_ed_session_delete (sm, s, thread_index, 1);
+	  return NAT_NEXT_DROP;
+	}
+      s->out2in.addr = outside_addr;
+      s->out2in.port = outside_port;
+    }
+  else
+    {
+      // static mapping
+      s->out2in.addr = outside_addr = sm_addr;
+      s->out2in.port = outside_port = sm_port;
+      s->in2out.addr = l_addr;
+      s->in2out.port = l_port;
+      s->nat_proto = nat_proto;
+      s->in2out.fib_index = rx_fib_index;
+      s->out2in.fib_index = outside_fib_index;
+      s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
+
+      // hairpinning?
+      int is_hairpinning = nat44_ed_external_sm_lookup (
+	sm, r_addr, r_port, nat_proto, outside_fib_index, &daddr, &dport);
+      s->flags |= is_hairpinning * SNAT_SESSION_FLAG_HAIRPINNING;
+
+      if (NAT_PROTOCOL_ICMP == nat_proto)
+	{
+	  nat_6t_o2i_flow_init (sm, thread_index, s, daddr, sm_port, sm_addr,
+				sm_port, s->out2in.fib_index, proto);
+	  nat_6t_flow_icmp_id_rewrite_set (&s->o2i, l_port);
+	}
+      else
+	{
+	  nat_6t_o2i_flow_init (sm, thread_index, s, daddr, dport, sm_addr,
+				sm_port, s->out2in.fib_index, proto);
+	  nat_6t_flow_dport_rewrite_set (&s->o2i, l_port);
+	}
+      nat_6t_flow_daddr_rewrite_set (&s->o2i, l_addr.as_u32);
+      nat_6t_flow_txfib_rewrite_set (&s->o2i, rx_fib_index);
+      if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 2))
+	{
+	  nat_elog_notice (sm, "out2in key add failed");
+	  goto error;
+	}
+    }
+
+  if (lb)
+    s->flags |= SNAT_SESSION_FLAG_LOAD_BALANCING;
+  s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
+  s->ext_host_addr = r_addr;
+  s->ext_host_port = r_port;
+
+  nat_6t_i2o_flow_init (sm, thread_index, s, l_addr, l_port, r_addr, r_port,
+			rx_fib_index, proto);
+  nat_6t_flow_saddr_rewrite_set (&s->i2o, outside_addr.as_u32);
+  nat_6t_flow_daddr_rewrite_set (&s->i2o, daddr.as_u32);
+  if (NAT_PROTOCOL_ICMP == nat_proto)
+    {
+      nat_6t_flow_icmp_id_rewrite_set (&s->i2o, outside_port);
+    }
+  else
+    {
+      nat_6t_flow_sport_rewrite_set (&s->i2o, outside_port);
+      nat_6t_flow_dport_rewrite_set (&s->i2o, dport);
+    }
+  nat_6t_flow_txfib_rewrite_set (&s->i2o, outside_fib_index);
+
+  if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 1))
+    {
+      nat_elog_notice (sm, "in2out key add failed");
+      goto error;
+    }
+
+  /* log NAT event */
+  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, 0);
+
+  per_vrf_sessions_register_session (s, thread_index);
+
+  *sessionp = s;
+  return next;
+error:
+  if (s)
+    {
+      if (!is_sm)
+	{
+	  snat_free_outside_address_and_port (sm->addresses, thread_index,
+					      &outside_addr, outside_port,
+					      nat_proto);
+	}
+      nat_ed_session_delete (sm, s, thread_index, 1);
+    }
+  *sessionp = s = NULL;
+  return NAT_NEXT_DROP;
+}
+
+static_always_inline int
+nat44_ed_not_translate (snat_main_t * sm, vlib_node_runtime_t * node,
+			u32 sw_if_index, ip4_header_t * ip, u32 proto,
+			u32 rx_fib_index, u32 thread_index)
+{
+  udp_header_t *udp = ip4_next_header (ip);
+  clib_bihash_kv_16_8_t kv, value;
+
+  init_ed_k (&kv, ip->dst_address, udp->dst_port, ip->src_address,
+	     udp->src_port, sm->outside_fib_index, ip->protocol);
+
+  /* NAT packet aimed at external address if has active sessions */
+  if (clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
+    {
+      /* or is static mappings */
+      ip4_address_t placeholder_addr;
+      u16 placeholder_port;
+      u32 placeholder_fib_index;
+      if (!snat_static_mapping_match
+	  (sm, ip->dst_address, udp->dst_port, sm->outside_fib_index, proto,
+	   &placeholder_addr, &placeholder_port, &placeholder_fib_index, 1, 0,
+	   0, 0, 0, 0, 0))
+	return 0;
+    }
+  else
+    return 0;
+
+  if (sm->forwarding_enabled)
+    return 1;
+
+  return snat_not_translate_fast (sm, node, sw_if_index, ip, proto,
+				  rx_fib_index);
+}
+
+static_always_inline int
+nat_not_translate_output_feature_fwd (snat_main_t * sm, ip4_header_t * ip,
+				      u32 thread_index, f64 now,
+				      vlib_main_t * vm, vlib_buffer_t * b)
+{
+  clib_bihash_kv_16_8_t kv, value;
+  snat_session_t *s = 0;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+
+  if (!sm->forwarding_enabled)
+    return 0;
+
+  if (ip->protocol == IP_PROTOCOL_ICMP)
+    {
+      ip4_address_t lookup_saddr, lookup_daddr;
+      u16 lookup_sport, lookup_dport;
+      u8 lookup_protocol;
+      if (nat_get_icmp_session_lookup_values (b, ip, &lookup_saddr,
+					      &lookup_sport, &lookup_daddr,
+					      &lookup_dport, &lookup_protocol))
+	return 0;
+      init_ed_k (&kv, lookup_saddr, lookup_sport, lookup_daddr, lookup_dport,
+		 0, lookup_protocol);
+    }
+  else if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
+    {
+      init_ed_k (&kv, ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
+		 ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port, 0,
+		 ip->protocol);
+    }
+  else
+    {
+      init_ed_k (&kv, ip->src_address, 0, ip->dst_address, 0, 0,
+		 ip->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));
+
+      if (is_fwd_bypass_session (s))
+	{
+	  if (ip->protocol == IP_PROTOCOL_TCP)
+	    {
+	      nat44_set_tcp_session_state_i2o (sm, now, s, b, 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 1;
+	}
+      else
+	return 0;
+    }
+
+  return 0;
+}
+
+static_always_inline int
+nat44_ed_not_translate_output_feature (snat_main_t * sm, ip4_header_t * ip,
+				       u16 src_port, u16 dst_port,
+				       u32 thread_index, u32 rx_sw_if_index,
+				       u32 tx_sw_if_index, f64 now)
+{
+  clib_bihash_kv_16_8_t kv, value;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  snat_interface_t *i;
+  snat_session_t *s;
+  u32 rx_fib_index = ip4_fib_table_get_index_for_sw_if_index (rx_sw_if_index);
+  u32 tx_fib_index = ip4_fib_table_get_index_for_sw_if_index (tx_sw_if_index);
+
+  /* src NAT check */
+  init_ed_k (&kv, ip->src_address, src_port, ip->dst_address, dst_port,
+	     tx_fib_index, ip->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));
+      if (nat44_is_ses_closed (s)
+	  && (!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, 1);
+	}
+      return 1;
+    }
+
+  /* dst NAT check */
+  init_ed_k (&kv, ip->dst_address, dst_port, ip->src_address, src_port,
+	     rx_fib_index, ip->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));
+
+      if (is_fwd_bypass_session (s))
+	return 0;
+
+      /* hairpinning */
+      pool_foreach (i, sm->output_feature_interfaces)
+       {
+        if ((nat_interface_is_inside (i)) && (rx_sw_if_index == i->sw_if_index))
+           return 0;
+      }
+      return 1;
+    }
+
+  return 0;
+}
+
+static inline u32
+icmp_in2out_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,
+			  nat_protocol_t nat_proto, snat_session_t **s_p)
+{
+  vlib_main_t *vm = vlib_get_main ();
+  u16 checksum;
+  int err;
+  snat_session_t *s = NULL;
+  u8 lookup_protocol = ip->protocol;
+  u16 lookup_sport, lookup_dport;
+  ip4_address_t lookup_saddr, lookup_daddr;
+
+  err = nat_get_icmp_session_lookup_values (b, ip, &lookup_saddr,
+					    &lookup_sport, &lookup_daddr,
+					    &lookup_dport, &lookup_protocol);
+  if (err != 0)
+    {
+      b->error = node->errors[err];
+      return NAT_NEXT_DROP;
+    }
+
+  if (vnet_buffer (b)->sw_if_index[VLIB_TX] != ~0)
+    {
+      if (PREDICT_FALSE (nat44_ed_not_translate_output_feature (
+	    sm, ip, lookup_sport, lookup_dport, thread_index, sw_if_index,
+	    vnet_buffer (b)->sw_if_index[VLIB_TX], now)))
+	{
+	  return next;
+	}
+    }
+  else
+    {
+      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node, sw_if_index, ip,
+						 NAT_PROTOCOL_ICMP,
+						 rx_fib_index, thread_index)))
+	{
+	  return next;
+	}
+    }
+
+  if (PREDICT_FALSE (icmp_type_is_error_message (
+	vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags)))
+    {
+      b->error = node->errors[NAT_IN2OUT_ED_ERROR_BAD_ICMP_TYPE];
+      return NAT_NEXT_DROP;
+    }
+
+  next = slow_path_ed (sm, b, ip->src_address, ip->dst_address, lookup_sport,
+		       lookup_dport, ip->protocol, rx_fib_index, &s, node,
+		       next, thread_index, vlib_time_now (vm));
+
+  if (NAT_NEXT_DROP == next)
+    goto out;
+
+  if (PREDICT_TRUE (!ip4_is_fragment (ip)))
+    {
+      ip_csum_t 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 (PREDICT_FALSE (checksum != 0 && checksum != 0xffff))
+	{
+	  next = NAT_NEXT_DROP;
+	  goto out;
+	}
+    }
+
+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);
+    }
+  *s_p = s;
+  return next;
+}
+
+static snat_session_t *
+nat44_ed_in2out_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;
+  clib_bihash_kv_16_8_t s_kv, s_value;
+  snat_static_mapping_t *m = NULL;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  snat_session_t *s = NULL;
+  u32 outside_fib_index = sm->outside_fib_index;
+  int i;
+  ip4_address_t new_src_addr = { 0 };
+  ip4_address_t new_dst_addr = ip->dst_address;
+
+  if (PREDICT_FALSE (
+	nat44_ed_maximum_sessions_exceeded (sm, rx_fib_index, thread_index)))
+    {
+      b->error = node->errors[NAT_IN2OUT_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_ipfix_logging_max_sessions (thread_index,
+				      sm->max_translations_per_thread);
+      nat_elog_notice (sm, "maximum sessions exceeded");
+      return 0;
+    }
+
+  switch (vec_len (sm->outside_fibs))
+    {
+    case 0:
+      outside_fib_index = sm->outside_fib_index;
+      break;
+    case 1:
+      outside_fib_index = sm->outside_fibs[0].fib_index;
+      break;
+    default:
+      outside_fib_index = nat_outside_fib_index_lookup (sm, ip->dst_address);
+      break;
+    }
+
+  init_nat_k (&kv, ip->src_address, 0, rx_fib_index, 0);
+
+  /* Try to find static mapping first */
+  if (!clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv, &value))
+    {
+      m = pool_elt_at_index (sm->static_mappings, value.value);
+      new_src_addr = m->external_addr;
+    }
+  else
+    {
+      pool_foreach (s, tsm->sessions)
+	{
+	  if (s->ext_host_addr.as_u32 == ip->dst_address.as_u32)
+	    {
+	      init_ed_k (&s_kv, s->out2in.addr, 0, ip->dst_address, 0,
+			 outside_fib_index, ip->protocol);
+	      if (clib_bihash_search_16_8 (&sm->flow_hash, &s_kv, &s_value))
+		{
+		  new_src_addr = s->out2in.addr;
+		}
+	      break;
+	    }
+	}
+
+      if (!new_src_addr.as_u32)
+	{
+	  for (i = 0; i < vec_len (sm->addresses); i++)
+	    {
+	      init_ed_k (&s_kv, sm->addresses[i].addr, 0, ip->dst_address, 0,
+			 outside_fib_index, ip->protocol);
+	      if (clib_bihash_search_16_8 (&sm->flow_hash, &s_kv, &s_value))
+		{
+		  new_src_addr = sm->addresses[i].addr;
+		}
+	    }
+	}
+    }
+
+  if (!new_src_addr.as_u32)
+    {
+      // could not allocate address for translation ...
+      return 0;
+    }
+
+  s = nat_ed_session_alloc (sm, thread_index, now, ip->protocol);
+  if (!s)
+    {
+      b->error = node->errors[NAT_IN2OUT_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_elog_warn (sm, "create NAT session failed");
+      return 0;
+    }
+
+  nat_6t_i2o_flow_init (sm, thread_index, s, ip->src_address, 0,
+			ip->dst_address, 0, rx_fib_index, ip->protocol);
+  nat_6t_flow_saddr_rewrite_set (&s->i2o, new_src_addr.as_u32);
+  nat_6t_flow_txfib_rewrite_set (&s->i2o, outside_fib_index);
+
+  // hairpinning?
+  int is_hairpinning =
+    nat44_ed_external_sm_lookup (sm, ip->dst_address, 0, NAT_PROTOCOL_OTHER,
+				 outside_fib_index, &new_dst_addr, NULL);
+  s->flags |= is_hairpinning * SNAT_SESSION_FLAG_HAIRPINNING;
+
+  nat_6t_flow_daddr_rewrite_set (&s->i2o, new_dst_addr.as_u32);
+  nat_6t_flow_txfib_rewrite_set (&s->i2o, outside_fib_index);
+
+  nat_6t_o2i_flow_init (sm, thread_index, s, new_dst_addr, 0, new_src_addr, 0,
+			outside_fib_index, ip->protocol);
+  nat_6t_flow_saddr_rewrite_set (&s->o2i, ip->dst_address.as_u32);
+  nat_6t_flow_daddr_rewrite_set (&s->o2i, ip->src_address.as_u32);
+  nat_6t_flow_txfib_rewrite_set (&s->o2i, rx_fib_index);
+
+  s->ext_host_addr.as_u32 = ip->dst_address.as_u32;
+  s->flags |= SNAT_SESSION_FLAG_UNKNOWN_PROTO;
+  s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
+  s->out2in.addr.as_u32 = new_src_addr.as_u32;
+  s->out2in.fib_index = outside_fib_index;
+  s->in2out.addr.as_u32 = ip->src_address.as_u32;
+  s->in2out.fib_index = rx_fib_index;
+  s->in2out.port = s->out2in.port = ip->protocol;
+  if (m)
+    s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
+
+  if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 1))
+    {
+      nat_elog_notice (sm, "in2out flow hash add failed");
+      nat_ed_session_delete (sm, s, thread_index, 1);
+      return NULL;
+    }
+
+  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_in2out_fast_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame,
+					  int is_output_feature)
+{
+  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];
+  u32 def_slow = is_output_feature ? NAT_NEXT_IN2OUT_ED_OUTPUT_SLOW_PATH
+    : NAT_NEXT_IN2OUT_ED_SLOW_PATH;
+
+  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, iph_offset0 = 0;
+      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++;
+
+      /* 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);
+	}
+
+      if (is_output_feature)
+	{
+	  iph_offset0 = vnet_buffer (b0)->ip.reass.save_rewrite_length;
+	}
+
+      next[0] = vnet_buffer2 (b0)->nat.arc_next;
+
+      ip0 =
+	(ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0) + iph_offset0);
+
+      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+      rx_fib_index0 =
+	fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index0);
+
+      if (PREDICT_FALSE (ip0->ttl == 1))
+	{
+	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+	  icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  next[0] = NAT_NEXT_ICMP_ERROR;
+	  goto trace0;
+	}
+
+      proto0 = ip_proto_to_nat_proto (ip0->protocol);
+
+      if (is_output_feature)
+	{
+	  if (PREDICT_FALSE
+	      (nat_not_translate_output_feature_fwd
+	       (sm, ip0, thread_index, now, vm, b0)))
+	    goto trace0;
+	}
+
+      if (PREDICT_FALSE (proto0 == 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_IN2OUT_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_protocol = ip0->protocol;
+	  lookup_saddr = ip0->src_address;
+	  lookup_daddr = ip0->dst_address;
+	  lookup_sport = vnet_buffer (b0)->ip.reass.l4_src_port;
+	  lookup_dport = vnet_buffer (b0)->ip.reass.l4_dst_port;
+	}
+
+      /* 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->i2o, b0, lookup_saddr, lookup_sport,
+				   lookup_daddr, lookup_dport, lookup_protocol,
+				   rx_fib_index0)
+		// for some hairpinning cases there are two "i2i" flows instead
+		// of i2o and o2i as both hosts are on inside
+		|| (s0->flags & SNAT_SESSION_FLAG_HAIRPINNING &&
+		    nat_6t_flow_match (
+		      &s0->o2i, 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, ip0->src_address, lookup_sport, ip0->dst_address,
+		 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] = def_slow;
+	  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] = def_slow;
+	    }
+	  else
+	    {
+	      // session in transitory timeout, drop
+	      b0->error = node->errors[NAT_IN2OUT_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)
+	{
+	  nat_free_session_data (sm, s0, thread_index, 0);
+	  nat_ed_session_delete (sm, s0, thread_index, 1);
+	  // session is closed, go slow path
+	  next[0] = def_slow;
+	  goto trace0;
+	}
+
+      b0->flags |= VNET_BUFFER_F_IS_NATED;
+
+      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 if (s0->flags & SNAT_SESSION_FLAG_HAIRPINNING &&
+	       nat_6t_flow_match (&s0->o2i, b0, lookup_saddr, lookup_sport,
+				  lookup_daddr, lookup_dport, lookup_protocol,
+				  rx_fib_index0))
+	{
+	  f = &s0->o2i;
+	}
+      else
+	{
+	  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, is_output_feature)))
+	{
+	  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;
+	}
+
+      switch (proto0)
+	{
+	case NAT_PROTOCOL_TCP:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.in2out.tcp,
+					 thread_index, sw_if_index0, 1);
+	  nat44_set_tcp_session_state_i2o (sm, now, s0, b0, thread_index);
+	  break;
+	case NAT_PROTOCOL_UDP:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.in2out.udp,
+					 thread_index, sw_if_index0, 1);
+	  break;
+	case NAT_PROTOCOL_ICMP:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.in2out.icmp,
+					 thread_index, sw_if_index0, 1);
+	  break;
+	case NAT_PROTOCOL_OTHER:
+	  vlib_increment_simple_counter (&sm->counters.fastpath.in2out.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)))
+	{
+	  nat_in2out_ed_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;
+	  t->lookup_skipped = lookup_skipped;
+	  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));
+	      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.in2out.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_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame,
+					  int is_output_feature)
+{
+  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, iph_offset0 = 0;
+      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;
+      int translation_error = NAT_ED_TRNSL_ERR_SUCCESS;
+
+      b0 = *b;
+
+      if (is_output_feature)
+	iph_offset0 = vnet_buffer (b0)->ip.reass.save_rewrite_length;
+
+      next[0] = vnet_buffer2 (b0)->nat.arc_next;
+
+      ip0 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0) +
+			      iph_offset0);
+
+      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+      rx_fib_index0 =
+	fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index0);
+
+      if (PREDICT_FALSE (ip0->ttl == 1))
+	{
+	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+	  icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  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_in2out_slowpath_unknown_proto (
+	    sm, b0, ip0, rx_fib_index0, thread_index, now, vm, node);
+	  if (!s0)
+	    next[0] = NAT_NEXT_DROP;
+
+	  if (NAT_ED_TRNSL_ERR_SUCCESS !=
+	      (translation_error = nat_6t_flow_buf_translate (
+		 sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
+	    {
+	      goto trace0;
+	    }
+
+	  vlib_increment_simple_counter (&sm->counters.slowpath.in2out.other,
+					 thread_index, sw_if_index0, 1);
+	  goto trace0;
+	}
+
+      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
+	{
+	  next[0] = icmp_in2out_ed_slow_path (sm, b0, ip0, icmp0, sw_if_index0,
+					      rx_fib_index0, node, next[0],
+					      now, thread_index, proto0, &s0);
+	  if (NAT_NEXT_DROP != next[0] && s0 &&
+	      NAT_ED_TRNSL_ERR_SUCCESS !=
+		(translation_error = nat_6t_flow_buf_translate (
+		   sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
+	    {
+	      goto trace0;
+	    }
+
+	  vlib_increment_simple_counter (&sm->counters.slowpath.in2out.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);
+      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)
+	{
+	  if (is_output_feature)
+	    {
+	      if (PREDICT_FALSE
+		  (nat44_ed_not_translate_output_feature
+		   (sm, ip0, vnet_buffer (b0)->ip.reass.l4_src_port,
+		    vnet_buffer (b0)->ip.reass.l4_dst_port, thread_index,
+		    sw_if_index0, vnet_buffer (b0)->sw_if_index[VLIB_TX],
+		    now)))
+		goto trace0;
+
+	      /*
+	       * Send DHCP packets to the ipv4 stack, or we won't
+	       * be able to use dhcp client on the outside interface
+	       */
+	      if (PREDICT_FALSE
+		  (proto0 == NAT_PROTOCOL_UDP
+		   && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
+		       clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_server))
+		   && ip0->dst_address.as_u32 == 0xffffffff))
+		goto trace0;
+	    }
+	  else
+	    {
+	      if (PREDICT_FALSE
+		  (nat44_ed_not_translate
+		   (sm, node, sw_if_index0, ip0, proto0, rx_fib_index0,
+		    thread_index)))
+		goto trace0;
+	    }
+
+	  next[0] =
+	    slow_path_ed (sm, b0, ip0->src_address, ip0->dst_address,
+			  vnet_buffer (b0)->ip.reass.l4_src_port,
+			  vnet_buffer (b0)->ip.reass.l4_dst_port,
+			  ip0->protocol, rx_fib_index0, &s0, node, next[0],
+			  thread_index, now);
+
+	  if (PREDICT_FALSE (next[0] == NAT_NEXT_DROP))
+	    goto trace0;
+
+	  if (PREDICT_FALSE (!s0))
+	    goto trace0;
+
+	}
+
+      b0->flags |= VNET_BUFFER_F_IS_NATED;
+
+      if (NAT_ED_TRNSL_ERR_SUCCESS !=
+	  (translation_error = nat_6t_flow_buf_translate (
+	     sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
+	{
+	  nat_free_session_data (sm, s0, thread_index, 0);
+	  nat_ed_session_delete (sm, s0, thread_index, 1);
+	  s0 = NULL;
+	  goto trace0;
+	}
+
+      if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
+	{
+	  vlib_increment_simple_counter (&sm->counters.slowpath.in2out.tcp,
+					 thread_index, sw_if_index0, 1);
+	  nat44_set_tcp_session_state_i2o (sm, now, s0, b0, thread_index);
+	}
+      else
+	{
+	  vlib_increment_simple_counter (&sm->counters.slowpath.in2out.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)))
+	{
+	  nat_in2out_ed_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));
+	      t->translation_via_i2of = 1;
+	    }
+
+	  else
+	    {
+	      t->session_index = ~0;
+	    }
+	}
+
+      if (next[0] == NAT_NEXT_DROP)
+	{
+	  vlib_increment_simple_counter (&sm->counters.slowpath.in2out.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_in2out_node) (vlib_main_t * vm,
+				     vlib_node_runtime_t * node,
+				     vlib_frame_t * frame)
+{
+  return nat44_ed_in2out_fast_path_node_fn_inline (vm, node, frame, 0);
+}
+
+VLIB_REGISTER_NODE (nat44_ed_in2out_node) = {
+  .name = "nat44-ed-in2out",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_in2out_ed_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
+  .error_strings = nat_in2out_ed_error_strings,
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+};
+
+VLIB_NODE_FN (nat44_ed_in2out_output_node) (vlib_main_t * vm,
+					    vlib_node_runtime_t * node,
+					    vlib_frame_t * frame)
+{
+  return nat44_ed_in2out_fast_path_node_fn_inline (vm, node, frame, 1);
+}
+
+VLIB_REGISTER_NODE (nat44_ed_in2out_output_node) = {
+  .name = "nat44-ed-in2out-output",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_in2out_ed_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
+  .error_strings = nat_in2out_ed_error_strings,
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+};
+
+VLIB_NODE_FN (nat44_ed_in2out_slowpath_node) (vlib_main_t * vm,
+					      vlib_node_runtime_t *
+					      node, vlib_frame_t * frame)
+{
+  return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 0);
+}
+
+VLIB_REGISTER_NODE (nat44_ed_in2out_slowpath_node) = {
+  .name = "nat44-ed-in2out-slowpath",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_in2out_ed_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
+  .error_strings = nat_in2out_ed_error_strings,
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+};
+
+VLIB_NODE_FN (nat44_ed_in2out_output_slowpath_node) (vlib_main_t * vm,
+						     vlib_node_runtime_t
+						     * node,
+						     vlib_frame_t * frame)
+{
+  return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 1);
+}
+
+VLIB_REGISTER_NODE (nat44_ed_in2out_output_slowpath_node) = {
+  .name = "nat44-ed-in2out-output-slowpath",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_in2out_ed_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN (nat_in2out_ed_error_strings),
+  .error_strings = nat_in2out_ed_error_strings,
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+};
+
+static u8 *
+format_nat_pre_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  nat_pre_trace_t *t = va_arg (*args, nat_pre_trace_t *);
+  return format (s, "in2out next_index %d arc_next_index %d", t->next_index,
+		 t->arc_next_index);
+}
+
+VLIB_NODE_FN (nat_pre_in2out_node)
+  (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  return nat_pre_node_fn_inline (vm, node, frame,
+				 NAT_NEXT_IN2OUT_ED_FAST_PATH);
+}
+
+VLIB_NODE_FN (nat_pre_in2out_output_node)
+  (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  return nat_pre_node_fn_inline (vm, node, frame,
+				 NAT_NEXT_IN2OUT_ED_OUTPUT_FAST_PATH);
+}
+
+VLIB_REGISTER_NODE (nat_pre_in2out_node) = {
+  .name = "nat-pre-in2out",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_pre_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = 0,
+};
+
+VLIB_REGISTER_NODE (nat_pre_in2out_output_node) = {
+  .name = "nat-pre-in2out-output",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_pre_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = 0,
+};
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */