nat64_in2out.c

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/*
 * 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 <nat/nat64/nat64.h>
#include <vnet/ip/ip6_to_ip4.h>
#include <vnet/fib/fib_table.h>
#include <nat/lib/nat_inlines.h>

typedef struct
{
  u32 sw_if_index;
  u32 next_index;
  u8 is_slow_path;
} nat64_in2out_trace_t;

static u8 *
format_nat64_in2out_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 *);
  nat64_in2out_trace_t *t = va_arg (*args, nat64_in2out_trace_t *);
  char *tag;

  tag = t->is_slow_path ? "NAT64-in2out-slowpath" : "NAT64-in2out";

  s =
    format (s, "%s: sw_if_index %d, next index %d", tag, t->sw_if_index,
            t->next_index);

  return s;
}

#define foreach_nat64_in2out_error                       \
_(UNSUPPORTED_PROTOCOL, "unsupported protocol")          \
_(NO_TRANSLATION, "no translation")                      \
_(UNKNOWN, "unknown")


typedef enum
{
#define _(sym,str) NAT64_IN2OUT_ERROR_##sym,
  foreach_nat64_in2out_error
#undef _
    NAT64_IN2OUT_N_ERROR,
} nat64_in2out_error_t;

static char *nat64_in2out_error_strings[] = {
#define _(sym,string) string,
  foreach_nat64_in2out_error
#undef _
};

typedef enum
{
  NAT64_IN2OUT_NEXT_IP4_LOOKUP,
  NAT64_IN2OUT_NEXT_IP6_LOOKUP,
  NAT64_IN2OUT_NEXT_DROP,
  NAT64_IN2OUT_NEXT_SLOWPATH,
  NAT64_IN2OUT_N_NEXT,
} nat64_in2out_next_t;

typedef struct nat64_in2out_set_ctx_t_
{
  vlib_buffer_t *b;
  vlib_main_t *vm;
  u32 thread_index;
} nat64_in2out_set_ctx_t;

static inline u8
nat64_not_translate (u32 sw_if_index, ip6_address_t ip6_addr)
{
  ip6_address_t *addr;
  ip6_main_t *im6 = &ip6_main;
  ip_lookup_main_t *lm6 = &im6->lookup_main;
  ip_interface_address_t *ia = 0;

  /* *INDENT-OFF* */
  foreach_ip_interface_address (lm6, ia, sw_if_index, 0,
  ({
        addr = ip_interface_address_get_address (lm6, ia);
        if (0 == ip6_address_compare (addr, &ip6_addr))
                return 1;
  }));
  /* *INDENT-ON* */

  return 0;
}

/**
 * @brief Check whether is a hairpinning.
 *
 * If the destination IP address of the packet is an IPv4 address assigned to
 * the NAT64 itself, then the packet is a hairpin packet.
 *
 * param dst_addr Destination address of the packet.
 *
 * @returns 1 if hairpinning, otherwise 0.
 */
static_always_inline int
is_hairpinning (ip6_address_t * dst_addr)
{
  nat64_main_t *nm = &nat64_main;
  int i;

  for (i = 0; i < vec_len (nm->addr_pool); i++)
    {
      if (nm->addr_pool[i].addr.as_u32 == dst_addr->as_u32[3])
        return 1;
    }

  return 0;
}

static int
nat64_in2out_tcp_udp (vlib_main_t * vm, vlib_buffer_t * p, u16 l4_offset,
                      u16 frag_hdr_offset, nat64_in2out_set_ctx_t * ctx)
{
  ip6_header_t *ip6;
  ip_csum_t csum = 0;
  ip4_header_t *ip4;
  u16 fragment_id;
  u8 frag_more;
  u16 frag_offset;
  nat64_main_t *nm = &nat64_main;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t old_saddr, old_daddr;
  ip4_address_t new_daddr;
  u32 sw_if_index, fib_index;
  u8 proto = vnet_buffer (p)->ip.reass.ip_proto;
  u16 sport = vnet_buffer (p)->ip.reass.l4_src_port;
  u16 dport = vnet_buffer (p)->ip.reass.l4_dst_port;
  nat64_db_t *db = &nm->db[ctx->thread_index];

  ip6 = vlib_buffer_get_current (p);

  vlib_buffer_advance (p, l4_offset - sizeof (*ip4));
  ip4 = vlib_buffer_get_current (p);

  u32 ip_version_traffic_class_and_flow_label =
    ip6->ip_version_traffic_class_and_flow_label;
  u16 payload_length = ip6->payload_length;
  u8 hop_limit = ip6->hop_limit;

  old_saddr.as_u64[0] = ip6->src_address.as_u64[0];
  old_saddr.as_u64[1] = ip6->src_address.as_u64[1];
  old_daddr.as_u64[0] = ip6->dst_address.as_u64[0];
  old_daddr.as_u64[1] = ip6->dst_address.as_u64[1];

  if (PREDICT_FALSE (frag_hdr_offset))
    {
      //Only the first fragment
      ip6_frag_hdr_t *hdr =
        (ip6_frag_hdr_t *) u8_ptr_add (ip6, frag_hdr_offset);
      fragment_id = frag_id_6to4 (hdr->identification);
      frag_more = ip6_frag_hdr_more (hdr);
      frag_offset = ip6_frag_hdr_offset (hdr);
    }
  else
    {
      fragment_id = 0;
      frag_offset = 0;
      frag_more = 0;
    }

  ip4->ip_version_and_header_length =
    IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS;
  ip4->tos = ip6_translate_tos (ip_version_traffic_class_and_flow_label);
  ip4->length =
    u16_net_add (payload_length, sizeof (*ip4) + sizeof (*ip6) - l4_offset);
  ip4->fragment_id = fragment_id;
  ip4->flags_and_fragment_offset =
    clib_host_to_net_u16 (frag_offset |
                          (frag_more ? IP4_HEADER_FLAG_MORE_FRAGMENTS : 0));
  ip4->ttl = hop_limit;
  ip4->protocol = (proto == IP_PROTOCOL_ICMP6) ? IP_PROTOCOL_ICMP : proto;

  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
  fib_index =
    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);

  ste =
    nat64_db_st_entry_find (db, &old_saddr, &old_daddr, sport, dport, proto,
                            fib_index, 1);

  if (ste)
    {
      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
      if (!bibe)
        return -1;
    }
  else
    {
      bibe =
        nat64_db_bib_entry_find (db, &old_saddr, sport, proto, fib_index, 1);

      if (!bibe)
        {
          u16 out_port;
          ip4_address_t out_addr;
          if (nat64_alloc_out_addr_and_port
              (fib_index, ip_proto_to_nat_proto (proto), &out_addr,
               &out_port, ctx->thread_index))
            return -1;

          bibe =
            nat64_db_bib_entry_create (ctx->thread_index, db,
                                       &old_saddr.ip6, &out_addr, sport,
                                       out_port, fib_index, proto, 0);
          if (!bibe)
            return -1;

          vlib_set_simple_counter (&nm->total_bibs, ctx->thread_index, 0,
                                   db->bib.bib_entries_num);
        }

      nat64_extract_ip4 (&old_daddr.ip6, &new_daddr, fib_index);
      ste =
        nat64_db_st_entry_create (ctx->thread_index, db, bibe,
                                  &old_daddr.ip6, &new_daddr, dport);
      if (!ste)
        return -1;

      vlib_set_simple_counter (&nm->total_sessions, ctx->thread_index, 0,
                               db->st.st_entries_num);
    }

  ip4->src_address.as_u32 = bibe->out_addr.as_u32;
  ip4->dst_address.as_u32 = ste->out_r_addr.as_u32;

  ip4->checksum = ip4_header_checksum (ip4);

  if (!vnet_buffer (p)->ip.reass.is_non_first_fragment)
    {
      udp_header_t *udp = (udp_header_t *) (ip4 + 1);
      udp->src_port = bibe->out_port;

      //UDP checksum is optional over IPv4
      if (proto == IP_PROTOCOL_UDP)
        {
          udp->checksum = 0;
        }
      else
        {
          tcp_header_t *tcp = (tcp_header_t *) (ip4 + 1);
          csum = ip_csum_sub_even (tcp->checksum, old_saddr.as_u64[0]);
          csum = ip_csum_sub_even (csum, old_saddr.as_u64[1]);
          csum = ip_csum_sub_even (csum, old_daddr.as_u64[0]);
          csum = ip_csum_sub_even (csum, old_daddr.as_u64[1]);
          csum = ip_csum_add_even (csum, ip4->dst_address.as_u32);
          csum = ip_csum_add_even (csum, ip4->src_address.as_u32);
          csum = ip_csum_sub_even (csum, sport);
          csum = ip_csum_add_even (csum, udp->src_port);
          mss_clamping (nm->mss_clamping, tcp, &csum);
          tcp->checksum = ip_csum_fold (csum);

          nat64_tcp_session_set_state (ste, tcp, 1);
        }
    }

  nat64_session_reset_timeout (ste, ctx->vm);

  return 0;
}

static int
nat64_in2out_icmp_set_cb (ip6_header_t * ip6, ip4_header_t * ip4, void *arg)
{
  nat64_main_t *nm = &nat64_main;
  nat64_in2out_set_ctx_t *ctx = arg;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t saddr, daddr;
  u32 sw_if_index, fib_index;
  icmp46_header_t *icmp = ip6_next_header (ip6);
  nat64_db_t *db = &nm->db[ctx->thread_index];

  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
  fib_index =
    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);

  saddr.as_u64[0] = ip6->src_address.as_u64[0];
  saddr.as_u64[1] = ip6->src_address.as_u64[1];
  daddr.as_u64[0] = ip6->dst_address.as_u64[0];
  daddr.as_u64[1] = ip6->dst_address.as_u64[1];

  if (icmp->type == ICMP4_echo_request || icmp->type == ICMP4_echo_reply)
    {
      u16 in_id = ((u16 *) (icmp))[2];
      ste =
        nat64_db_st_entry_find (db, &saddr, &daddr, in_id, 0,
                                IP_PROTOCOL_ICMP, fib_index, 1);

      if (ste)
        {
          bibe =
            nat64_db_bib_entry_by_index (db, IP_PROTOCOL_ICMP,
                                         ste->bibe_index);
          if (!bibe)
            return -1;
        }
      else
        {
          bibe =
            nat64_db_bib_entry_find (db, &saddr, in_id,
                                     IP_PROTOCOL_ICMP, fib_index, 1);

          if (!bibe)
            {
              u16 out_id;
              ip4_address_t out_addr;
              if (nat64_alloc_out_addr_and_port
                  (fib_index, NAT_PROTOCOL_ICMP, &out_addr, &out_id,
                   ctx->thread_index))
                return -1;

              bibe =
                nat64_db_bib_entry_create (ctx->thread_index, db,
                                           &ip6->src_address, &out_addr,
                                           in_id, out_id, fib_index,
                                           IP_PROTOCOL_ICMP, 0);
              if (!bibe)
                return -1;

              vlib_set_simple_counter (&nm->total_bibs, ctx->thread_index, 0,
                                       db->bib.bib_entries_num);
            }

          nat64_extract_ip4 (&ip6->dst_address, &daddr.ip4, fib_index);
          ste =
            nat64_db_st_entry_create (ctx->thread_index, db, bibe,
                                      &ip6->dst_address, &daddr.ip4, 0);
          if (!ste)
            return -1;

          vlib_set_simple_counter (&nm->total_sessions, ctx->thread_index, 0,
                                   db->st.st_entries_num);
        }

      nat64_session_reset_timeout (ste, ctx->vm);

      ip4->src_address.as_u32 = bibe->out_addr.as_u32;
      ((u16 *) (icmp))[2] = bibe->out_port;

      ip4->dst_address.as_u32 = ste->out_r_addr.as_u32;
    }
  else
    {
      if (!vec_len (nm->addr_pool))
        return -1;

      ip4->src_address.as_u32 = nm->addr_pool[0].addr.as_u32;
      nat64_extract_ip4 (&ip6->dst_address, &ip4->dst_address, fib_index);
    }

  return 0;
}

static int
nat64_in2out_inner_icmp_set_cb (ip6_header_t * ip6, ip4_header_t * ip4,
                                void *arg)
{
  nat64_main_t *nm = &nat64_main;
  nat64_in2out_set_ctx_t *ctx = arg;
  nat64_db_st_entry_t *ste;
  nat64_db_bib_entry_t *bibe;
  ip46_address_t saddr, daddr;
  u32 sw_if_index, fib_index;
  u8 proto = ip6->protocol;
  nat64_db_t *db = &nm->db[ctx->thread_index];

  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
  fib_index =
    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);

  saddr.as_u64[0] = ip6->src_address.as_u64[0];
  saddr.as_u64[1] = ip6->src_address.as_u64[1];
  daddr.as_u64[0] = ip6->dst_address.as_u64[0];
  daddr.as_u64[1] = ip6->dst_address.as_u64[1];

  if (proto == IP_PROTOCOL_ICMP6)
    {
      icmp46_header_t *icmp = ip6_next_header (ip6);
      u16 in_id = ((u16 *) (icmp))[2];
      proto = IP_PROTOCOL_ICMP;

      if (!
          (icmp->type == ICMP4_echo_request
           || icmp->type == ICMP4_echo_reply))
        return -1;

      ste =
        nat64_db_st_entry_find (db, &daddr, &saddr, in_id, 0, proto,
                                fib_index, 1);
      if (!ste)
        return -1;

      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
      if (!bibe)
        return -1;

      ip4->dst_address.as_u32 = bibe->out_addr.as_u32;
      ((u16 *) (icmp))[2] = bibe->out_port;
      ip4->src_address.as_u32 = ste->out_r_addr.as_u32;
    }
  else
    {
      udp_header_t *udp = ip6_next_header (ip6);
      tcp_header_t *tcp = ip6_next_header (ip6);
      u16 *checksum;
      ip_csum_t csum;

      u16 sport = udp->src_port;
      u16 dport = udp->dst_port;

      ste =
        nat64_db_st_entry_find (db, &daddr, &saddr, dport, sport, proto,
                                fib_index, 1);
      if (!ste)
        return -1;

      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
      if (!bibe)
        return -1;

      ip4->dst_address.as_u32 = bibe->out_addr.as_u32;
      udp->dst_port = bibe->out_port;
      ip4->src_address.as_u32 = ste->out_r_addr.as_u32;

      if (proto == IP_PROTOCOL_TCP)
        checksum = &tcp->checksum;
      else
        checksum = &udp->checksum;
      csum = ip_csum_sub_even (*checksum, dport);
      csum = ip_csum_add_even (csum, udp->dst_port);
      *checksum = ip_csum_fold (csum);
    }

  return 0;
}

typedef struct unk_proto_st_walk_ctx_t_
{
  ip6_address_t src_addr;
  ip6_address_t dst_addr;
  ip4_address_t out_addr;
  u32 fib_index;
  u32 thread_index;
  u8 proto;
} unk_proto_st_walk_ctx_t;

static int
unk_proto_st_walk (nat64_db_st_entry_t * ste, void *arg)
{
  nat64_main_t *nm = &nat64_main;
  unk_proto_st_walk_ctx_t *ctx = arg;
  nat64_db_bib_entry_t *bibe;
  ip46_address_t saddr, daddr;
  nat64_db_t *db = &nm->db[ctx->thread_index];

  if (ip6_address_is_equal (&ste->in_r_addr, &ctx->dst_addr))
    {
      bibe = nat64_db_bib_entry_by_index (db, ste->proto, ste->bibe_index);
      if (!bibe)
        return -1;

      if (ip6_address_is_equal (&bibe->in_addr, &ctx->src_addr)
          && bibe->fib_index == ctx->fib_index)
        {
          clib_memset (&saddr, 0, sizeof (saddr));
          saddr.ip4.as_u32 = bibe->out_addr.as_u32;
          clib_memset (&daddr, 0, sizeof (daddr));
          nat64_extract_ip4 (&ctx->dst_addr, &daddr.ip4, ctx->fib_index);

          if (nat64_db_st_entry_find
              (db, &daddr, &saddr, 0, 0, ctx->proto, ctx->fib_index, 0))
            return -1;

          ctx->out_addr.as_u32 = bibe->out_addr.as_u32;
          return 1;
        }
    }

  return 0;
}

static int
nat64_in2out_unk_proto (vlib_main_t * vm, vlib_buffer_t * p, u8 l4_protocol,
                        u16 l4_offset, u16 frag_hdr_offset,
                        nat64_in2out_set_ctx_t * s_ctx)
{
  ip6_header_t *ip6;
  ip4_header_t *ip4;
  u16 fragment_id;
  u16 frag_offset;
  u8 frag_more;

  ip6 = vlib_buffer_get_current (p);

  ip4 = (ip4_header_t *) u8_ptr_add (ip6, l4_offset - sizeof (*ip4));

  vlib_buffer_advance (p, l4_offset - sizeof (*ip4));

  if (PREDICT_FALSE (frag_hdr_offset))
    {
      //Only the first fragment
      ip6_frag_hdr_t *hdr =
        (ip6_frag_hdr_t *) u8_ptr_add (ip6, frag_hdr_offset);
      fragment_id = frag_id_6to4 (hdr->identification);
      frag_offset = ip6_frag_hdr_offset (hdr);
      frag_more = ip6_frag_hdr_more (hdr);
    }
  else
    {
      fragment_id = 0;
      frag_offset = 0;
      frag_more = 0;
    }

  nat64_main_t *nm = &nat64_main;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t saddr, daddr, addr;
  u32 sw_if_index, fib_index;
  int i;
  nat64_db_t *db = &nm->db[s_ctx->thread_index];

  sw_if_index = vnet_buffer (s_ctx->b)->sw_if_index[VLIB_RX];
  fib_index =
    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);

  saddr.as_u64[0] = ip6->src_address.as_u64[0];
  saddr.as_u64[1] = ip6->src_address.as_u64[1];
  daddr.as_u64[0] = ip6->dst_address.as_u64[0];
  daddr.as_u64[1] = ip6->dst_address.as_u64[1];

  ste =
    nat64_db_st_entry_find (db, &saddr, &daddr, 0, 0, l4_protocol, fib_index,
                            1);

  if (ste)
    {
      bibe = nat64_db_bib_entry_by_index (db, l4_protocol, ste->bibe_index);
      if (!bibe)
        return -1;
    }
  else
    {
      bibe =
        nat64_db_bib_entry_find (db, &saddr, 0, l4_protocol, fib_index, 1);

      if (!bibe)
        {
          /* Choose same out address as for TCP/UDP session to same dst */
          unk_proto_st_walk_ctx_t ctx = {
            .src_addr.as_u64[0] = ip6->src_address.as_u64[0],
            .src_addr.as_u64[1] = ip6->src_address.as_u64[1],
            .dst_addr.as_u64[0] = ip6->dst_address.as_u64[0],
            .dst_addr.as_u64[1] = ip6->dst_address.as_u64[1],
            .out_addr.as_u32 = 0,
            .fib_index = fib_index,
            .proto = l4_protocol,
            .thread_index = s_ctx->thread_index,
          };

          nat64_db_st_walk (db, IP_PROTOCOL_TCP, unk_proto_st_walk, &ctx);

          if (!ctx.out_addr.as_u32)
            nat64_db_st_walk (db, IP_PROTOCOL_UDP, unk_proto_st_walk, &ctx);

          /* Verify if out address is not already in use for protocol */
          clib_memset (&addr, 0, sizeof (addr));
          addr.ip4.as_u32 = ctx.out_addr.as_u32;
          if (nat64_db_bib_entry_find (db, &addr, 0, l4_protocol, 0, 0))
            ctx.out_addr.as_u32 = 0;

          if (!ctx.out_addr.as_u32)
            {
              for (i = 0; i < vec_len (nm->addr_pool); i++)
                {
                  addr.ip4.as_u32 = nm->addr_pool[i].addr.as_u32;
                  if (!nat64_db_bib_entry_find
                      (db, &addr, 0, l4_protocol, 0, 0))
                    break;
                }
            }

          if (!ctx.out_addr.as_u32)
            return -1;

          bibe =
            nat64_db_bib_entry_create (s_ctx->thread_index, db,
                                       &ip6->src_address, &ctx.out_addr,
                                       0, 0, fib_index, l4_protocol, 0);
          if (!bibe)
            return -1;

          vlib_set_simple_counter (&nm->total_bibs, s_ctx->thread_index, 0,
                                   db->bib.bib_entries_num);
        }

      nat64_extract_ip4 (&ip6->dst_address, &daddr.ip4, fib_index);
      ste =
        nat64_db_st_entry_create (s_ctx->thread_index, db, bibe,
                                  &ip6->dst_address, &daddr.ip4, 0);
      if (!ste)
        return -1;

      vlib_set_simple_counter (&nm->total_sessions, s_ctx->thread_index, 0,
                               db->st.st_entries_num);
    }

  nat64_session_reset_timeout (ste, s_ctx->vm);

  ip4->src_address.as_u32 = bibe->out_addr.as_u32;
  ip4->dst_address.as_u32 = ste->out_r_addr.as_u32;

  ip4->ip_version_and_header_length =
    IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS;
  ip4->tos = ip6_translate_tos (ip6->ip_version_traffic_class_and_flow_label);
  ip4->length = u16_net_add (ip6->payload_length,
                             sizeof (*ip4) + sizeof (*ip6) - l4_offset);
  ip4->fragment_id = fragment_id;
  ip4->flags_and_fragment_offset =
    clib_host_to_net_u16 (frag_offset |
                          (frag_more ? IP4_HEADER_FLAG_MORE_FRAGMENTS : 0));
  ip4->ttl = ip6->hop_limit;
  ip4->protocol = l4_protocol;
  ip4->checksum = ip4_header_checksum (ip4);

  return 0;
}

static int
nat64_in2out_tcp_udp_hairpinning (vlib_main_t * vm, vlib_buffer_t * b,
                                  ip6_header_t * ip6, u32 l4_offset,
                                  u32 thread_index)
{
  nat64_main_t *nm = &nat64_main;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t saddr, daddr;
  u32 sw_if_index, fib_index;
  udp_header_t *udp = (udp_header_t *) u8_ptr_add (ip6, l4_offset);
  tcp_header_t *tcp = (tcp_header_t *) u8_ptr_add (ip6, l4_offset);
  u8 proto = vnet_buffer (b)->ip.reass.ip_proto;
  u16 sport = vnet_buffer (b)->ip.reass.l4_src_port;
  u16 dport = vnet_buffer (b)->ip.reass.l4_dst_port;
  u16 *checksum = NULL;
  ip_csum_t csum = 0;
  nat64_db_t *db = &nm->db[thread_index];

  sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
  fib_index =
    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);

  saddr.as_u64[0] = ip6->src_address.as_u64[0];
  saddr.as_u64[1] = ip6->src_address.as_u64[1];
  daddr.as_u64[0] = ip6->dst_address.as_u64[0];
  daddr.as_u64[1] = ip6->dst_address.as_u64[1];

  if (!vnet_buffer (b)->ip.reass.is_non_first_fragment)
    {
      if (proto == IP_PROTOCOL_UDP)
        checksum = &udp->checksum;
      else
        checksum = &tcp->checksum;
      csum = ip_csum_sub_even (*checksum, ip6->src_address.as_u64[0]);
      csum = ip_csum_sub_even (csum, ip6->src_address.as_u64[1]);
      csum = ip_csum_sub_even (csum, ip6->dst_address.as_u64[0]);
      csum = ip_csum_sub_even (csum, ip6->dst_address.as_u64[1]);
    }

  ste =
    nat64_db_st_entry_find (db, &saddr, &daddr, sport, dport, proto,
                            fib_index, 1);

  if (ste)
    {
      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
      if (!bibe)
        return -1;
    }
  else
    {
      bibe = nat64_db_bib_entry_find (db, &saddr, sport, proto, fib_index, 1);

      if (!bibe)
        {
          u16 out_port;
          ip4_address_t out_addr;
          if (nat64_alloc_out_addr_and_port
              (fib_index, ip_proto_to_nat_proto (proto), &out_addr,
               &out_port, thread_index))
            return -1;

          bibe =
            nat64_db_bib_entry_create (thread_index, db, &ip6->src_address,
                                       &out_addr, sport, out_port, fib_index,
                                       proto, 0);
          if (!bibe)
            return -1;

          vlib_set_simple_counter (&nm->total_bibs, thread_index, 0,
                                   db->bib.bib_entries_num);
        }

      nat64_extract_ip4 (&ip6->dst_address, &daddr.ip4, fib_index);
      ste =
        nat64_db_st_entry_create (thread_index, db, bibe, &ip6->dst_address,
                                  &daddr.ip4, dport);
      if (!ste)
        return -1;

      vlib_set_simple_counter (&nm->total_sessions, thread_index, 0,
                               db->st.st_entries_num);
    }

  if (proto == IP_PROTOCOL_TCP)
    nat64_tcp_session_set_state (ste, tcp, 1);

  nat64_session_reset_timeout (ste, vm);

  if (!vnet_buffer (b)->ip.reass.is_non_first_fragment)
    {
      udp->src_port = bibe->out_port;
    }

  nat64_compose_ip6 (&ip6->src_address, &bibe->out_addr, fib_index);

  clib_memset (&daddr, 0, sizeof (daddr));
  daddr.ip4.as_u32 = ste->out_r_addr.as_u32;

  bibe = 0;
  /* *INDENT-OFF* */
  vec_foreach (db, nm->db)
    {
      bibe = nat64_db_bib_entry_find (db, &daddr, dport, proto, 0, 0);

      if (bibe)
        break;
    }
  /* *INDENT-ON* */

  if (!bibe)
    return -1;

  ip6->dst_address.as_u64[0] = bibe->in_addr.as_u64[0];
  ip6->dst_address.as_u64[1] = bibe->in_addr.as_u64[1];

  if (!vnet_buffer (b)->ip.reass.is_non_first_fragment)
    {
      csum = ip_csum_add_even (csum, ip6->src_address.as_u64[0]);
      csum = ip_csum_add_even (csum, ip6->src_address.as_u64[1]);
      csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[0]);
      csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[1]);
      csum = ip_csum_sub_even (csum, sport);
      csum = ip_csum_sub_even (csum, dport);
      udp->dst_port = bibe->in_port;
      csum = ip_csum_add_even (csum, udp->src_port);
      csum = ip_csum_add_even (csum, udp->dst_port);
      *checksum = ip_csum_fold (csum);
    }

  return 0;
}

static int
nat64_in2out_icmp_hairpinning (vlib_main_t * vm, vlib_buffer_t * b,
                               ip6_header_t * ip6, u32 thread_index)
{
  nat64_main_t *nm = &nat64_main;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  icmp46_header_t *icmp = ip6_next_header (ip6);
  ip6_header_t *inner_ip6;
  ip46_address_t saddr, daddr;
  u32 sw_if_index, fib_index;
  u8 proto;
  udp_header_t *udp;
  tcp_header_t *tcp;
  u16 *checksum, sport, dport;
  ip_csum_t csum;
  nat64_db_t *db = &nm->db[thread_index];

  if (icmp->type == ICMP6_echo_request || icmp->type == ICMP6_echo_reply)
    return -1;

  inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8);

  proto = inner_ip6->protocol;

  if (proto == IP_PROTOCOL_ICMP6)
    return -1;

  sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
  fib_index =
    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);

  saddr.as_u64[0] = inner_ip6->src_address.as_u64[0];
  saddr.as_u64[1] = inner_ip6->src_address.as_u64[1];
  daddr.as_u64[0] = inner_ip6->dst_address.as_u64[0];
  daddr.as_u64[1] = inner_ip6->dst_address.as_u64[1];

  udp = ip6_next_header (inner_ip6);
  tcp = ip6_next_header (inner_ip6);

  sport = udp->src_port;
  dport = udp->dst_port;

  if (proto == IP_PROTOCOL_UDP)
    checksum = &udp->checksum;
  else
    checksum = &tcp->checksum;

  csum = ip_csum_sub_even (*checksum, inner_ip6->src_address.as_u64[0]);
  csum = ip_csum_sub_even (csum, inner_ip6->src_address.as_u64[1]);
  csum = ip_csum_sub_even (csum, inner_ip6->dst_address.as_u64[0]);
  csum = ip_csum_sub_even (csum, inner_ip6->dst_address.as_u64[1]);
  csum = ip_csum_sub_even (csum, sport);
  csum = ip_csum_sub_even (csum, dport);

  ste =
    nat64_db_st_entry_find (db, &daddr, &saddr, dport, sport, proto,
                            fib_index, 1);
  if (!ste)
    return -1;

  bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
  if (!bibe)
    return -1;

  dport = udp->dst_port = bibe->out_port;
  nat64_compose_ip6 (&inner_ip6->dst_address, &bibe->out_addr, fib_index);

  clib_memset (&saddr, 0, sizeof (saddr));
  clib_memset (&daddr, 0, sizeof (daddr));
  saddr.ip4.as_u32 = ste->out_r_addr.as_u32;
  daddr.ip4.as_u32 = bibe->out_addr.as_u32;

  ste = 0;
  /* *INDENT-OFF* */
  vec_foreach (db, nm->db)
    {
      ste = nat64_db_st_entry_find (db, &saddr, &daddr, sport, dport, proto,
                                    0, 0);

      if (ste)
        break;
    }
  /* *INDENT-ON* */

  if (!ste)
    return -1;

  bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
  if (!bibe)
    return -1;

  inner_ip6->src_address.as_u64[0] = bibe->in_addr.as_u64[0];
  inner_ip6->src_address.as_u64[1] = bibe->in_addr.as_u64[1];
  udp->src_port = bibe->in_port;

  csum = ip_csum_add_even (csum, inner_ip6->src_address.as_u64[0]);
  csum = ip_csum_add_even (csum, inner_ip6->src_address.as_u64[1]);
  csum = ip_csum_add_even (csum, inner_ip6->dst_address.as_u64[0]);
  csum = ip_csum_add_even (csum, inner_ip6->dst_address.as_u64[1]);
  csum = ip_csum_add_even (csum, udp->src_port);
  csum = ip_csum_add_even (csum, udp->dst_port);
  *checksum = ip_csum_fold (csum);

  if (!vec_len (nm->addr_pool))
    return -1;

  nat64_compose_ip6 (&ip6->src_address, &nm->addr_pool[0].addr, fib_index);
  ip6->dst_address.as_u64[0] = inner_ip6->src_address.as_u64[0];
  ip6->dst_address.as_u64[1] = inner_ip6->src_address.as_u64[1];

  icmp->checksum = 0;
  csum = ip_csum_with_carry (0, ip6->payload_length);
  csum = ip_csum_with_carry (csum, clib_host_to_net_u16 (ip6->protocol));
  csum = ip_csum_with_carry (csum, ip6->src_address.as_u64[0]);
  csum = ip_csum_with_carry (csum, ip6->src_address.as_u64[1]);
  csum = ip_csum_with_carry (csum, ip6->dst_address.as_u64[0]);
  csum = ip_csum_with_carry (csum, ip6->dst_address.as_u64[1]);
  csum =
    ip_incremental_checksum (csum, icmp,
                             clib_net_to_host_u16 (ip6->payload_length));
  icmp->checksum = ~ip_csum_fold (csum);

  return 0;
}

static int
nat64_in2out_unk_proto_hairpinning (vlib_main_t * vm, vlib_buffer_t * b,
                                    ip6_header_t * ip6, u32 thread_index)
{
  nat64_main_t *nm = &nat64_main;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t saddr, daddr, addr;
  u32 sw_if_index, fib_index;
  u8 proto = ip6->protocol;
  int i;
  nat64_db_t *db = &nm->db[thread_index];

  sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
  fib_index =
    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);

  saddr.as_u64[0] = ip6->src_address.as_u64[0];
  saddr.as_u64[1] = ip6->src_address.as_u64[1];
  daddr.as_u64[0] = ip6->dst_address.as_u64[0];
  daddr.as_u64[1] = ip6->dst_address.as_u64[1];

  ste =
    nat64_db_st_entry_find (db, &saddr, &daddr, 0, 0, proto, fib_index, 1);

  if (ste)
    {
      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
      if (!bibe)
        return -1;
    }
  else
    {
      bibe = nat64_db_bib_entry_find (db, &saddr, 0, proto, fib_index, 1);

      if (!bibe)
        {
          /* Choose same out address as for TCP/UDP session to same dst */
          unk_proto_st_walk_ctx_t ctx = {
            .src_addr.as_u64[0] = ip6->src_address.as_u64[0],
            .src_addr.as_u64[1] = ip6->src_address.as_u64[1],
            .dst_addr.as_u64[0] = ip6->dst_address.as_u64[0],
            .dst_addr.as_u64[1] = ip6->dst_address.as_u64[1],
            .out_addr.as_u32 = 0,
            .fib_index = fib_index,
            .proto = proto,
            .thread_index = thread_index,
          };

          nat64_db_st_walk (db, IP_PROTOCOL_TCP, unk_proto_st_walk, &ctx);

          if (!ctx.out_addr.as_u32)
            nat64_db_st_walk (db, IP_PROTOCOL_UDP, unk_proto_st_walk, &ctx);

          /* Verify if out address is not already in use for protocol */
          clib_memset (&addr, 0, sizeof (addr));
          addr.ip4.as_u32 = ctx.out_addr.as_u32;
          if (nat64_db_bib_entry_find (db, &addr, 0, proto, 0, 0))
            ctx.out_addr.as_u32 = 0;

          if (!ctx.out_addr.as_u32)
            {
              for (i = 0; i < vec_len (nm->addr_pool); i++)
                {
                  addr.ip4.as_u32 = nm->addr_pool[i].addr.as_u32;
                  if (!nat64_db_bib_entry_find (db, &addr, 0, proto, 0, 0))
                    break;
                }
            }

          if (!ctx.out_addr.as_u32)
            return -1;

          bibe =
            nat64_db_bib_entry_create (thread_index, db, &ip6->src_address,
                                       &ctx.out_addr, 0, 0, fib_index, proto,
                                       0);
          if (!bibe)
            return -1;

          vlib_set_simple_counter (&nm->total_bibs, thread_index, 0,
                                   db->bib.bib_entries_num);
        }

      nat64_extract_ip4 (&ip6->dst_address, &daddr.ip4, fib_index);
      ste =
        nat64_db_st_entry_create (thread_index, db, bibe, &ip6->dst_address,
                                  &daddr.ip4, 0);
      if (!ste)
        return -1;

      vlib_set_simple_counter (&nm->total_sessions, thread_index, 0,
                               db->st.st_entries_num);
    }

  nat64_session_reset_timeout (ste, vm);

  nat64_compose_ip6 (&ip6->src_address, &bibe->out_addr, fib_index);

  clib_memset (&daddr, 0, sizeof (daddr));
  daddr.ip4.as_u32 = ste->out_r_addr.as_u32;

  bibe = 0;
  /* *INDENT-OFF* */
  vec_foreach (db, nm->db)
    {
      bibe = nat64_db_bib_entry_find (db, &daddr, 0, proto, 0, 0);

      if (bibe)
        break;
    }
  /* *INDENT-ON* */

  if (!bibe)
    return -1;

  ip6->dst_address.as_u64[0] = bibe->in_addr.as_u64[0];
  ip6->dst_address.as_u64[1] = bibe->in_addr.as_u64[1];

  return 0;
}

static inline uword
nat64_in2out_node_fn_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
                             vlib_frame_t * frame, u8 is_slow_path)
{
  u32 n_left_from, *from, *to_next;
  nat64_in2out_next_t next_index;
  u32 thread_index = vm->thread_index;
  nat64_main_t *nm = &nat64_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;
          ip6_header_t *ip60;
          u16 l4_offset0, frag_hdr_offset0;
          u8 l4_protocol0;
          u32 proto0;
          nat64_in2out_set_ctx_t ctx0;
          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);
          ip60 = vlib_buffer_get_current (b0);

          sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];

          ctx0.b = b0;
          ctx0.vm = vm;
          ctx0.thread_index = thread_index;

          next0 = NAT64_IN2OUT_NEXT_IP4_LOOKUP;

          if (PREDICT_FALSE
              (ip6_parse
               (vm, b0, ip60, b0->current_length, &l4_protocol0, &l4_offset0,
                &frag_hdr_offset0)))
            {
              next0 = NAT64_IN2OUT_NEXT_DROP;
              b0->error = node->errors[NAT64_IN2OUT_ERROR_UNKNOWN];
              goto trace0;
            }

          if (nat64_not_translate (sw_if_index0, ip60->dst_address))
            {
              next0 = NAT64_IN2OUT_NEXT_IP6_LOOKUP;
              goto trace0;
            }

          proto0 = ip_proto_to_nat_proto (l4_protocol0);

          if (is_slow_path)
            {
              if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_OTHER))
                {
                  vlib_increment_simple_counter (&nm->counters.in2out.other,
                                                 thread_index, sw_if_index0,
                                                 1);
                  if (is_hairpinning (&ip60->dst_address))
                    {
                      next0 = NAT64_IN2OUT_NEXT_IP6_LOOKUP;
                      if (nat64_in2out_unk_proto_hairpinning
                          (vm, b0, ip60, thread_index))
                        {
                          next0 = NAT64_IN2OUT_NEXT_DROP;
                          b0->error =
                            node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
                        }
                      goto trace0;
                    }

                  if (nat64_in2out_unk_proto
                      (vm, b0, l4_protocol0, l4_offset0, frag_hdr_offset0,
                       &ctx0))
                    {
                      next0 = NAT64_IN2OUT_NEXT_DROP;
                      b0->error =
                        node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
                      goto trace0;
                    }
                }
              goto trace0;
            }
          else
            {
              if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_OTHER))
                {
                  next0 = NAT64_IN2OUT_NEXT_SLOWPATH;
                  goto trace0;
                }
            }

          if (proto0 == NAT_PROTOCOL_ICMP)
            {
              vlib_increment_simple_counter (&nm->counters.in2out.icmp,
                                             thread_index, sw_if_index0, 1);
              if (is_hairpinning (&ip60->dst_address))
                {
                  next0 = NAT64_IN2OUT_NEXT_IP6_LOOKUP;
                  if (nat64_in2out_icmp_hairpinning
                      (vm, b0, ip60, thread_index))
                    {
                      next0 = NAT64_IN2OUT_NEXT_DROP;
                      b0->error =
                        node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
                    }
                  goto trace0;
                }

              if (icmp6_to_icmp
                  (vm, b0, nat64_in2out_icmp_set_cb, &ctx0,
                   nat64_in2out_inner_icmp_set_cb, &ctx0))
                {
                  next0 = NAT64_IN2OUT_NEXT_DROP;
                  b0->error = node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
                  goto trace0;
                }
            }
          else if (proto0 == NAT_PROTOCOL_TCP || proto0 == NAT_PROTOCOL_UDP)
            {
              if (proto0 == NAT_PROTOCOL_TCP)
                vlib_increment_simple_counter (&nm->counters.in2out.tcp,
                                               thread_index, sw_if_index0, 1);
              else
                vlib_increment_simple_counter (&nm->counters.in2out.udp,
                                               thread_index, sw_if_index0, 1);

              if (is_hairpinning (&ip60->dst_address))
                {
                  next0 = NAT64_IN2OUT_NEXT_IP6_LOOKUP;
                  if (nat64_in2out_tcp_udp_hairpinning
                      (vm, b0, ip60, l4_offset0, thread_index))
                    {
                      next0 = NAT64_IN2OUT_NEXT_DROP;
                      b0->error =
                        node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
                    }
                  goto trace0;
                }

              if (nat64_in2out_tcp_udp
                  (vm, b0, l4_offset0, frag_hdr_offset0, &ctx0))
                {
                  next0 = NAT64_IN2OUT_NEXT_DROP;
                  b0->error = node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
                  goto trace0;
                }
            }

        trace0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat64_in2out_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
              t->next_index = next0;
              t->is_slow_path = is_slow_path;
            }

          if (next0 == NAT64_IN2OUT_NEXT_DROP)
            {
              vlib_increment_simple_counter (&nm->counters.in2out.drops,
                                             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 (nat64_in2out_node) (vlib_main_t * vm,
                                  vlib_node_runtime_t * node,
                                  vlib_frame_t * frame)
{
  return nat64_in2out_node_fn_inline (vm, node, frame, 0);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat64_in2out_node) = {
  .name = "nat64-in2out",
  .vector_size = sizeof (u32),
  .format_trace = format_nat64_in2out_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat64_in2out_error_strings),
  .error_strings = nat64_in2out_error_strings,
  .n_next_nodes = NAT64_IN2OUT_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
    [NAT64_IN2OUT_NEXT_DROP] = "error-drop",
    [NAT64_IN2OUT_NEXT_IP4_LOOKUP] = "ip4-lookup",
    [NAT64_IN2OUT_NEXT_IP6_LOOKUP] = "ip6-lookup",
    [NAT64_IN2OUT_NEXT_SLOWPATH] = "nat64-in2out-slowpath",
  },
};
/* *INDENT-ON* */

VLIB_NODE_FN (nat64_in2out_slowpath_node) (vlib_main_t * vm,
                                           vlib_node_runtime_t * node,
                                           vlib_frame_t * frame)
{
  return nat64_in2out_node_fn_inline (vm, node, frame, 1);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat64_in2out_slowpath_node) = {
  .name = "nat64-in2out-slowpath",
  .vector_size = sizeof (u32),
  .format_trace = format_nat64_in2out_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat64_in2out_error_strings),
  .error_strings = nat64_in2out_error_strings,
  .n_next_nodes = NAT64_IN2OUT_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
    [NAT64_IN2OUT_NEXT_DROP] = "error-drop",
    [NAT64_IN2OUT_NEXT_IP4_LOOKUP] = "ip4-lookup",
    [NAT64_IN2OUT_NEXT_IP6_LOOKUP] = "ip6-lookup",
    [NAT64_IN2OUT_NEXT_SLOWPATH] = "nat64-in2out-slowpath",
  },
};
/* *INDENT-ON* */

typedef struct nat64_in2out_frag_set_ctx_t_
{
  vlib_main_t *vm;
  u32 sess_index;
  u32 thread_index;
  u16 l4_offset;
  u8 proto;
  u8 first_frag;
} nat64_in2out_frag_set_ctx_t;


#define foreach_nat64_in2out_handoff_error                       \
_(CONGESTION_DROP, "congestion drop")                            \
_(SAME_WORKER, "same worker")                                    \
_(DO_HANDOFF, "do handoff")

typedef enum
{
#define _(sym,str) NAT64_IN2OUT_HANDOFF_ERROR_##sym,
  foreach_nat64_in2out_handoff_error
#undef _
    NAT64_IN2OUT_HANDOFF_N_ERROR,
} nat64_in2out_handoff_error_t;

static char *nat64_in2out_handoff_error_strings[] = {
#define _(sym,string) string,
  foreach_nat64_in2out_handoff_error
#undef _
};

typedef struct
{
  u32 next_worker_index;
} nat64_in2out_handoff_trace_t;

static u8 *
format_nat64_in2out_handoff_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 *);
  nat64_in2out_handoff_trace_t *t =
    va_arg (*args, nat64_in2out_handoff_trace_t *);

  s =
    format (s, "NAT64-IN2OUT-HANDOFF: next-worker %d", t->next_worker_index);

  return s;
}

VLIB_NODE_FN (nat64_in2out_handoff_node) (vlib_main_t * vm,
                                          vlib_node_runtime_t * node,
                                          vlib_frame_t * frame)
{
  nat64_main_t *nm = &nat64_main;
  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
  u32 n_enq, n_left_from, *from;
  u16 thread_indices[VLIB_FRAME_SIZE], *ti;
  u32 fq_index;
  u32 thread_index = vm->thread_index;
  u32 do_handoff = 0, same_worker = 0;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  vlib_get_buffers (vm, from, bufs, n_left_from);

  b = bufs;
  ti = thread_indices;

  fq_index = nm->fq_in2out_index;

  while (n_left_from > 0)
    {
      ip6_header_t *ip0;

      ip0 = vlib_buffer_get_current (b[0]);
      ti[0] = nat64_get_worker_in2out (&ip0->src_address);

      if (ti[0] != thread_index)
        do_handoff++;
      else
        same_worker++;

      if (PREDICT_FALSE
          ((node->flags & VLIB_NODE_FLAG_TRACE)
           && (b[0]->flags & VLIB_BUFFER_IS_TRACED)))
        {
          nat64_in2out_handoff_trace_t *t =
            vlib_add_trace (vm, node, b[0], sizeof (*t));
          t->next_worker_index = ti[0];
        }

      n_left_from -= 1;
      ti += 1;
      b += 1;
    }

  n_enq =
    vlib_buffer_enqueue_to_thread (vm, fq_index, from, thread_indices,
                                   frame->n_vectors, 1);

  if (n_enq < frame->n_vectors)
    vlib_node_increment_counter (vm, node->node_index,
                                 NAT64_IN2OUT_HANDOFF_ERROR_CONGESTION_DROP,
                                 frame->n_vectors - n_enq);
  vlib_node_increment_counter (vm, node->node_index,
                               NAT64_IN2OUT_HANDOFF_ERROR_SAME_WORKER,
                               same_worker);
  vlib_node_increment_counter (vm, node->node_index,
                               NAT64_IN2OUT_HANDOFF_ERROR_DO_HANDOFF,
                               do_handoff);

  return frame->n_vectors;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat64_in2out_handoff_node) = {
  .name = "nat64-in2out-handoff",
  .vector_size = sizeof (u32),
  .format_trace = format_nat64_in2out_handoff_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(nat64_in2out_handoff_error_strings),
  .error_strings = nat64_in2out_handoff_error_strings,

  .n_next_nodes = 1,

  .next_nodes = {
    [0] = "error-drop",
  },
};
/* *INDENT-ON* */

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