/*
 * nat44_ei.c - nat44 endpoint dependent plugin
 * * Copyright (c) 2020 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.
 */

#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/fib/ip4_fib.h>

#include <nat/nat44-ei/nat44_ei.h>
#include <nat/nat44-ei/nat44_ei_inlines.h>
#include <nat/nat44-ei/nat44_ei_hairpinning.h>

/* NAT buffer flags */
#define NAT44_EI_FLAG_HAIRPINNING (1 << 0)

typedef enum
{
  NAT44_EI_HAIRPIN_SRC_NEXT_DROP,
  NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT,
  NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT_WH,
  NAT44_EI_HAIRPIN_SRC_NEXT_INTERFACE_OUTPUT,
  NAT44_EI_HAIRPIN_SRC_N_NEXT,
} nat44_ei_hairpin_src_next_t;

typedef enum
{
  NAT44_EI_HAIRPIN_NEXT_LOOKUP,
  NAT44_EI_HAIRPIN_NEXT_DROP,
  NAT44_EI_HAIRPIN_NEXT_HANDOFF,
  NAT44_EI_HAIRPIN_N_NEXT,
} nat44_ei_hairpin_next_t;

typedef struct
{
  ip4_address_t addr;
  u16 port;
  u32 fib_index;
  u32 session_index;
} nat44_ei_hairpin_trace_t;

static u8 *
format_nat44_ei_hairpin_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_ei_hairpin_trace_t *t = va_arg (*args, nat44_ei_hairpin_trace_t *);

  s = format (s, "new dst addr %U port %u fib-index %u", format_ip4_address,
	      &t->addr, clib_net_to_host_u16 (t->port), t->fib_index);
  if (~0 == t->session_index)
    {
      s = format (s, " is-static-mapping");
    }
  else
    {
      s = format (s, " session-index %u", t->session_index);
    }

  return s;
}

extern vnet_feature_arc_registration_t vnet_feat_arc_ip4_local;

static_always_inline int
nat44_ei_is_hairpinning (nat44_ei_main_t *nm, ip4_address_t *dst_addr)
{
  nat44_ei_address_t *ap;
  clib_bihash_kv_8_8_t kv, value;

  vec_foreach (ap, nm->addresses)
    {
      if (ap->addr.as_u32 == dst_addr->as_u32)
	return 1;
    }

  init_nat_k (&kv, *dst_addr, 0, 0, 0);
  if (!clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv, &value))
    return 1;

  return 0;
}

#ifndef CLIB_MARCH_VARIANT
void
nat44_ei_hairpinning_sm_unknown_proto (nat44_ei_main_t *nm, vlib_buffer_t *b,
				       ip4_header_t *ip)
{
  clib_bihash_kv_8_8_t kv, value;
  nat44_ei_static_mapping_t *m;
  u32 old_addr, new_addr;
  ip_csum_t sum;

  init_nat_k (&kv, ip->dst_address, 0, 0, 0);
  if (clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv, &value))
    return;

  m = pool_elt_at_index (nm->static_mappings, value.value);

  old_addr = ip->dst_address.as_u32;
  new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
  sum = ip->checksum;
  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
  ip->checksum = ip_csum_fold (sum);

  if (vnet_buffer (b)->sw_if_index[VLIB_TX] == ~0)
    vnet_buffer (b)->sw_if_index[VLIB_TX] = m->fib_index;
}
#endif

#ifndef CLIB_MARCH_VARIANT
int
nat44_ei_hairpinning (vlib_main_t *vm, vlib_node_runtime_t *node,
		      nat44_ei_main_t *nm, u32 thread_index, vlib_buffer_t *b0,
		      ip4_header_t *ip0, udp_header_t *udp0,
		      tcp_header_t *tcp0, u32 proto0, int do_trace,
		      u32 *required_thread_index)
{
  nat44_ei_session_t *s0 = NULL;
  clib_bihash_kv_8_8_t kv0, value0;
  ip_csum_t sum0;
  u32 new_dst_addr0 = 0, old_dst_addr0, si = ~0;
  u16 new_dst_port0 = ~0, old_dst_port0;
  int rv;
  ip4_address_t sm0_addr;
  u16 sm0_port;
  u32 sm0_fib_index;
  u32 old_sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_TX];

  /* Check if destination is static mappings */
  if (!nat44_ei_static_mapping_match (
	ip0->dst_address, udp0->dst_port, nm->outside_fib_index, proto0,
	&sm0_addr, &sm0_port, &sm0_fib_index, 1 /* by external */, 0, 0))
    {
      new_dst_addr0 = sm0_addr.as_u32;
      new_dst_port0 = sm0_port;
      vnet_buffer (b0)->sw_if_index[VLIB_TX] = sm0_fib_index;
    }
  /* or active session */
  else
    {
      init_nat_k (&kv0, ip0->dst_address, udp0->dst_port,
		  nm->outside_fib_index, proto0);
      rv = clib_bihash_search_8_8 (&nm->out2in, &kv0, &value0);
      if (rv)
	{
	  rv = 0;
	  goto trace;
	}

      if (thread_index != nat_value_get_thread_index (&value0))
	{
	  *required_thread_index = nat_value_get_thread_index (&value0);
	  return 0;
	}

      si = nat_value_get_session_index (&value0);
      s0 = pool_elt_at_index (nm->per_thread_data[thread_index].sessions, si);
      new_dst_addr0 = s0->in2out.addr.as_u32;
      new_dst_port0 = s0->in2out.port;
      vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
    }

  /* Check if anything has changed and if not, then return 0. This
     helps avoid infinite loop, repeating the three nodes
     nat44-hairpinning-->ip4-lookup-->ip4-local, in case nothing has
     changed. */
  old_dst_addr0 = ip0->dst_address.as_u32;
  old_dst_port0 = tcp0->dst;
  if (new_dst_addr0 == old_dst_addr0 && new_dst_port0 == old_dst_port0 &&
      vnet_buffer (b0)->sw_if_index[VLIB_TX] == old_sw_if_index)
    return 0;

  /* Destination is behind the same NAT, use internal address and port */
  if (new_dst_addr0)
    {
      old_dst_addr0 = ip0->dst_address.as_u32;
      ip0->dst_address.as_u32 = new_dst_addr0;
      sum0 = ip0->checksum;
      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0, ip4_header_t,
			     dst_address);
      ip0->checksum = ip_csum_fold (sum0);

      old_dst_port0 = tcp0->dst;
      if (PREDICT_TRUE (new_dst_port0 != old_dst_port0))
	{
	  if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
	    {
	      tcp0->dst = new_dst_port0;
	      sum0 = tcp0->checksum;
	      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0,
				     ip4_header_t, dst_address);
	      sum0 = ip_csum_update (sum0, old_dst_port0, new_dst_port0,
				     ip4_header_t /* cheat */, length);
	      tcp0->checksum = ip_csum_fold (sum0);
	    }
	  else
	    {
	      udp0->dst_port = new_dst_port0;
	      udp0->checksum = 0;
	    }
	}
      else
	{
	  if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
	    {
	      sum0 = tcp0->checksum;
	      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0,
				     ip4_header_t, dst_address);
	      tcp0->checksum = ip_csum_fold (sum0);
	    }
	}
      rv = 1;
      goto trace;
    }
  rv = 0;
trace:
  if (do_trace && PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
				 (b0->flags & VLIB_BUFFER_IS_TRACED)))
    {
      nat44_ei_hairpin_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
      t->addr.as_u32 = new_dst_addr0;
      t->port = new_dst_port0;
      t->fib_index = vnet_buffer (b0)->sw_if_index[VLIB_TX];
      if (s0)
	{
	  t->session_index = si;
	}
      else
	{
	  t->session_index = ~0;
	}
    }
  return rv;
}
#endif

#ifndef CLIB_MARCH_VARIANT
u32
nat44_ei_icmp_hairpinning (nat44_ei_main_t *nm, vlib_buffer_t *b0,
			   u32 thread_index, ip4_header_t *ip0,
			   icmp46_header_t *icmp0, u32 *required_thread_index)
{
  clib_bihash_kv_8_8_t kv0, value0;
  u32 old_dst_addr0, new_dst_addr0;
  u32 old_addr0, new_addr0;
  u16 old_port0, new_port0;
  u16 old_checksum0, new_checksum0;
  u32 si, ti = 0;
  ip_csum_t sum0;
  nat44_ei_session_t *s0;
  nat44_ei_static_mapping_t *m0;

  if (icmp_type_is_error_message (
	vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags))
    {
      ip4_header_t *inner_ip0 = 0;
      tcp_udp_header_t *l4_header = 0;

      inner_ip0 = (ip4_header_t *) ((icmp_echo_header_t *) (icmp0 + 1) + 1);
      l4_header = ip4_next_header (inner_ip0);
      u32 protocol = ip_proto_to_nat_proto (inner_ip0->protocol);

      if (protocol != NAT_PROTOCOL_TCP && protocol != NAT_PROTOCOL_UDP)
	return 1;

      init_nat_k (&kv0, ip0->dst_address, l4_header->src_port,
		  nm->outside_fib_index, protocol);
      if (clib_bihash_search_8_8 (&nm->out2in, &kv0, &value0))
	return 1;
      ti = nat_value_get_thread_index (&value0);
      if (ti != thread_index)
	{
	  *required_thread_index = ti;
	  return 1;
	}
      si = nat_value_get_session_index (&value0);
      s0 = pool_elt_at_index (nm->per_thread_data[ti].sessions, si);
      new_dst_addr0 = s0->in2out.addr.as_u32;
      vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;

      /* update inner source IP address */
      old_addr0 = inner_ip0->src_address.as_u32;
      inner_ip0->src_address.as_u32 = new_dst_addr0;
      new_addr0 = inner_ip0->src_address.as_u32;
      sum0 = icmp0->checksum;
      sum0 =
	ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t, src_address);
      icmp0->checksum = ip_csum_fold (sum0);

      /* update inner IP header checksum */
      old_checksum0 = inner_ip0->checksum;
      sum0 = inner_ip0->checksum;
      sum0 =
	ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t, src_address);
      inner_ip0->checksum = ip_csum_fold (sum0);
      new_checksum0 = inner_ip0->checksum;
      sum0 = icmp0->checksum;
      sum0 = ip_csum_update (sum0, old_checksum0, new_checksum0, ip4_header_t,
			     checksum);
      icmp0->checksum = ip_csum_fold (sum0);

      /* update inner source port */
      old_port0 = l4_header->src_port;
      l4_header->src_port = s0->in2out.port;
      new_port0 = l4_header->src_port;
      sum0 = icmp0->checksum;
      sum0 = ip_csum_update (sum0, old_port0, new_port0, tcp_udp_header_t,
			     src_port);
      icmp0->checksum = ip_csum_fold (sum0);
    }
  else
    {
      init_nat_k (&kv0, ip0->dst_address, 0, nm->outside_fib_index, 0);
      if (clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv0,
				  &value0))
	{
	  icmp_echo_header_t *echo0 = (icmp_echo_header_t *) (icmp0 + 1);
	  u16 icmp_id0 = echo0->identifier;
	  init_nat_k (&kv0, ip0->dst_address, icmp_id0, nm->outside_fib_index,
		      NAT_PROTOCOL_ICMP);
	  int rv = clib_bihash_search_8_8 (&nm->out2in, &kv0, &value0);
	  if (!rv)
	    {
	      ti = nat_value_get_thread_index (&value0);
	      if (ti != thread_index)
		{
		  *required_thread_index = ti;
		  return 1;
		}
	      si = nat_value_get_session_index (&value0);
	      s0 = pool_elt_at_index (nm->per_thread_data[ti].sessions, si);
	      new_dst_addr0 = s0->in2out.addr.as_u32;
	      vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
	      echo0->identifier = s0->in2out.port;
	      sum0 = icmp0->checksum;
	      sum0 = ip_csum_update (sum0, icmp_id0, s0->in2out.port,
				     icmp_echo_header_t, identifier);
	      icmp0->checksum = ip_csum_fold (sum0);
	      goto change_addr;
	    }

	  return 1;
	}

      m0 = pool_elt_at_index (nm->static_mappings, value0.value);

      new_dst_addr0 = m0->local_addr.as_u32;
      if (vnet_buffer (b0)->sw_if_index[VLIB_TX] == ~0)
	vnet_buffer (b0)->sw_if_index[VLIB_TX] = m0->fib_index;
    }
change_addr:
  /* Destination is behind the same NAT, use internal address and port */
  if (new_dst_addr0)
    {
      old_dst_addr0 = ip0->dst_address.as_u32;
      ip0->dst_address.as_u32 = new_dst_addr0;
      sum0 = ip0->checksum;
      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0, ip4_header_t,
			     dst_address);
      ip0->checksum = ip_csum_fold (sum0);
    }
  return 0;
}
#endif

void nat44_ei_hairpinning_unknown_proto (nat44_ei_main_t *nm, vlib_buffer_t *b,
					 ip4_header_t *ip);

#ifndef CLIB_MARCH_VARIANT
void
nat44_ei_hairpinning_unknown_proto (nat44_ei_main_t *nm, vlib_buffer_t *b,
				    ip4_header_t *ip)
{
  clib_bihash_kv_8_8_t kv, value;
  nat44_ei_static_mapping_t *m;
  u32 old_addr, new_addr;
  ip_csum_t sum;

  init_nat_k (&kv, ip->dst_address, 0, 0, 0);
  if (clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv, &value))
    return;

  m = pool_elt_at_index (nm->static_mappings, value.value);

  old_addr = ip->dst_address.as_u32;
  new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
  sum = ip->checksum;
  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
  ip->checksum = ip_csum_fold (sum);

  if (vnet_buffer (b)->sw_if_index[VLIB_TX] == ~0)
    vnet_buffer (b)->sw_if_index[VLIB_TX] = m->fib_index;
}
#endif

VLIB_NODE_FN (nat44_ei_hairpin_src_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next;
  nat44_ei_hairpin_src_next_t next_index;
  nat44_ei_main_t *nm = &nat44_ei_main;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from > 0 && n_left_to_next > 0)
	{
	  u32 bi0;
	  vlib_buffer_t *b0;
	  u32 next0;
	  nat44_ei_interface_t *i;
	  u32 sw_if_index0;

	  /* speculatively enqueue b0 to the current next frame */
	  bi0 = from[0];
	  to_next[0] = bi0;
	  from += 1;
	  to_next += 1;
	  n_left_from -= 1;
	  n_left_to_next -= 1;

	  b0 = vlib_get_buffer (vm, bi0);
	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	  vnet_feature_next (&next0, b0);

	  pool_foreach (i, nm->output_feature_interfaces)
	    {
	      /* Only packets from NAT inside interface */
	      if ((nat44_ei_interface_is_inside (i)) &&
		  (sw_if_index0 == i->sw_if_index))
		{
		  if (PREDICT_FALSE ((vnet_buffer (b0)->snat.flags) &
				     NAT44_EI_FLAG_HAIRPINNING))
		    {
		      if (PREDICT_TRUE (nm->num_workers > 1))
			next0 = NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT_WH;
		      else
			next0 = NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT;
		    }
		  break;
		}
	    }

	  if (next0 != NAT44_EI_HAIRPIN_SRC_NEXT_DROP)
	    {
	      vlib_increment_simple_counter (
		&nm->counters.hairpinning, vm->thread_index, sw_if_index0, 1);
	    }

	  /* verify speculative enqueue, maybe switch current next frame */
	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
					   n_left_to_next, bi0, next0);
	}

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  return frame->n_vectors;
}

VLIB_NODE_FN (nat44_ei_hairpin_dst_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next;
  u32 thread_index = vm->thread_index;
  nat44_ei_hairpin_next_t next_index;
  nat44_ei_main_t *nm = &nat44_ei_main;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from > 0 && n_left_to_next > 0)
	{
	  u32 bi0;
	  vlib_buffer_t *b0;
	  u32 next0;
	  ip4_header_t *ip0;
	  u32 proto0;
	  u32 sw_if_index0;
	  u32 required_thread_index = thread_index;

	  /* speculatively enqueue b0 to the current next frame */
	  bi0 = from[0];
	  to_next[0] = bi0;
	  from += 1;
	  to_next += 1;
	  n_left_from -= 1;
	  n_left_to_next -= 1;

	  b0 = vlib_get_buffer (vm, bi0);
	  next0 = NAT44_EI_HAIRPIN_NEXT_LOOKUP;
	  ip0 = vlib_buffer_get_current (b0);
	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];

	  proto0 = ip_proto_to_nat_proto (ip0->protocol);

	  vnet_buffer (b0)->snat.flags = 0;
	  if (PREDICT_FALSE (nat44_ei_is_hairpinning (nm, &ip0->dst_address)))
	    {
	      if (proto0 == NAT_PROTOCOL_TCP || proto0 == NAT_PROTOCOL_UDP)
		{
		  udp_header_t *udp0 = ip4_next_header (ip0);
		  tcp_header_t *tcp0 = (tcp_header_t *) udp0;

		  nat44_ei_hairpinning (vm, node, nm, thread_index, b0, ip0,
					udp0, tcp0, proto0, 1 /* do_trace */,
					&required_thread_index);
		}
	      else if (proto0 == NAT_PROTOCOL_ICMP)
		{
		  icmp46_header_t *icmp0 = ip4_next_header (ip0);

		  nat44_ei_icmp_hairpinning (nm, b0, thread_index, ip0, icmp0,
					     &required_thread_index);
		}
	      else
		{
		  nat44_ei_hairpinning_unknown_proto (nm, b0, ip0);
		}

	      vnet_buffer (b0)->snat.flags = NAT44_EI_FLAG_HAIRPINNING;
	    }

	  if (thread_index != required_thread_index)
	    {
	      vnet_buffer (b0)->snat.required_thread_index =
		required_thread_index;
	      next0 = NAT44_EI_HAIRPIN_NEXT_HANDOFF;
	    }

	  if (next0 != NAT44_EI_HAIRPIN_NEXT_DROP)
	    {
	      vlib_increment_simple_counter (
		&nm->counters.hairpinning, vm->thread_index, sw_if_index0, 1);
	    }

	  /* verify speculative enqueue, maybe switch current next frame */
	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
					   n_left_to_next, bi0, next0);
	}

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  return frame->n_vectors;
}

VLIB_NODE_FN (nat44_ei_hairpinning_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next;
  u32 thread_index = vm->thread_index;
  nat44_ei_hairpin_next_t next_index;
  nat44_ei_main_t *nm = &nat44_ei_main;
  vnet_feature_main_t *fm = &feature_main;
  u8 arc_index = vnet_feat_arc_ip4_local.feature_arc_index;
  vnet_feature_config_main_t *cm = &fm->feature_config_mains[arc_index];

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from > 0 && n_left_to_next > 0)
	{
	  u32 bi0;
	  vlib_buffer_t *b0;
	  u32 next0;
	  ip4_header_t *ip0;
	  u32 proto0;
	  udp_header_t *udp0;
	  tcp_header_t *tcp0;
	  u32 sw_if_index0;
	  u32 required_thread_index = thread_index;

	  /* speculatively enqueue b0 to the current next frame */
	  bi0 = from[0];
	  to_next[0] = bi0;
	  from += 1;
	  to_next += 1;
	  n_left_from -= 1;
	  n_left_to_next -= 1;

	  b0 = vlib_get_buffer (vm, bi0);
	  ip0 = vlib_buffer_get_current (b0);
	  udp0 = ip4_next_header (ip0);
	  tcp0 = (tcp_header_t *) udp0;
	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];

	  proto0 = ip_proto_to_nat_proto (ip0->protocol);
	  int next0_resolved = 0;

	  if (nat44_ei_hairpinning (vm, node, nm, thread_index, b0, ip0, udp0,
				    tcp0, proto0, 1 /* do_trace */,
				    &required_thread_index))
	    {
	      next0 = NAT44_EI_HAIRPIN_NEXT_LOOKUP;
	      next0_resolved = 1;
	    }

	  if (thread_index != required_thread_index)
	    {
	      vnet_buffer (b0)->snat.required_thread_index =
		required_thread_index;
	      next0 = NAT44_EI_HAIRPIN_NEXT_HANDOFF;
	      next0_resolved = 1;
	    }

	  if (!next0_resolved)
	    vnet_get_config_data (&cm->config_main, &b0->current_config_index,
				  &next0, 0);

	  if (next0 != NAT44_EI_HAIRPIN_NEXT_DROP)
	    {
	      vlib_increment_simple_counter (
		&nm->counters.hairpinning, vm->thread_index, sw_if_index0, 1);
	    }

	  /* verify speculative enqueue, maybe switch current next frame */
	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
					   n_left_to_next, bi0, next0);
	}

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  return frame->n_vectors;
}

VLIB_NODE_FN (nat44_ei_hairpinning_dst_handoff_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return nat44_ei_hairpinning_handoff_fn_inline (
    vm, node, frame, nat44_ei_main.hairpin_dst_fq_index);
}

VLIB_NODE_FN (nat44_ei_hairpinning_handoff_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return nat44_ei_hairpinning_handoff_fn_inline (
    vm, node, frame, nat44_ei_main.hairpinning_fq_index);
}

VLIB_REGISTER_NODE (nat44_ei_hairpinning_dst_handoff_node) = {
  .name = "nat44-ei-hairpin-dst-handoff",
  .vector_size = sizeof (u32),
  .n_errors = ARRAY_LEN(nat44_ei_hairpinning_handoff_error_strings),
  .error_strings = nat44_ei_hairpinning_handoff_error_strings,
  .format_trace = format_nat44_ei_hairpinning_handoff_trace,

  .n_next_nodes = 1,

  .next_nodes = {
    [0] = "error-drop",
  },
};

VLIB_REGISTER_NODE (nat44_ei_hairpinning_handoff_node) = {
  .name = "nat44-ei-hairpinning-handoff",
  .vector_size = sizeof (u32),
  .n_errors = ARRAY_LEN(nat44_ei_hairpinning_handoff_error_strings),
  .error_strings = nat44_ei_hairpinning_handoff_error_strings,
  .format_trace = format_nat44_ei_hairpinning_handoff_trace,

  .n_next_nodes = 1,

  .next_nodes = {
    [0] = "error-drop",
  },
};

VLIB_REGISTER_NODE (nat44_ei_hairpin_src_node) = {
  .name = "nat44-ei-hairpin-src",
  .vector_size = sizeof (u32),
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_next_nodes = NAT44_EI_HAIRPIN_SRC_N_NEXT,
  .next_nodes = {
     [NAT44_EI_HAIRPIN_SRC_NEXT_DROP] = "error-drop",
     [NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT] = "nat44-ei-in2out-output",
     [NAT44_EI_HAIRPIN_SRC_NEXT_INTERFACE_OUTPUT] = "interface-output",
     [NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT_WH] = "nat44-ei-in2out-output-worker-handoff",
  },
};

VLIB_REGISTER_NODE (nat44_ei_hairpin_dst_node) = {
  .name = "nat44-ei-hairpin-dst",
  .vector_size = sizeof (u32),
  .type = VLIB_NODE_TYPE_INTERNAL,
  .format_trace = format_nat44_ei_hairpin_trace,
  .n_next_nodes = NAT44_EI_HAIRPIN_N_NEXT,
  .next_nodes = {
    [NAT44_EI_HAIRPIN_NEXT_DROP] = "error-drop",
    [NAT44_EI_HAIRPIN_NEXT_LOOKUP] = "ip4-lookup",
    [NAT44_EI_HAIRPIN_NEXT_HANDOFF] = "nat44-ei-hairpin-dst-handoff",
  },
};

VLIB_REGISTER_NODE (nat44_ei_hairpinning_node) = {
  .name = "nat44-ei-hairpinning",
  .vector_size = sizeof (u32),
  .type = VLIB_NODE_TYPE_INTERNAL,
  .format_trace = format_nat44_ei_hairpin_trace,
  .n_next_nodes = NAT44_EI_HAIRPIN_N_NEXT,
  .next_nodes = {
    [NAT44_EI_HAIRPIN_NEXT_DROP] = "error-drop",
    [NAT44_EI_HAIRPIN_NEXT_LOOKUP] = "ip4-lookup",
    [NAT44_EI_HAIRPIN_NEXT_HANDOFF] = "nat44-ei-hairpinning-handoff",
  },
};

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */