nat64_out2in.c

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/*
 * Copyright (c) 2017 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 NAT64 IPv4 to IPv6 translation (otside to inside network)
 */

#include <nat/nat64.h>
#include <nat/nat_reass.h>
#include <nat/nat_inlines.h>
#include <vnet/ip/ip4_to_ip6.h>
#include <vnet/fib/ip4_fib.h>
#include <vnet/udp/udp.h>

typedef struct
{
  u32 sw_if_index;
  u32 next_index;
} nat64_out2in_trace_t;

static u8 *
format_nat64_out2in_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  nat64_out2in_trace_t *t = va_arg (*args, nat64_out2in_trace_t *);

  s =
    format (s, "NAT64-out2in: sw_if_index %d, next index %d", t->sw_if_index,
            t->next_index);

  return s;
}

typedef struct
{
  u32 sw_if_index;
  u32 next_index;
  u8 cached;
} nat64_out2in_reass_trace_t;

static u8 *
format_nat64_out2in_reass_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_out2in_reass_trace_t *t =
    va_arg (*args, nat64_out2in_reass_trace_t *);

  s =
    format (s, "NAT64-out2in-reass: sw_if_index %d, next index %d, status %s",
            t->sw_if_index, t->next_index,
            t->cached ? "cached" : "translated");

  return s;
}


#define foreach_nat64_out2in_error                       \
_(UNSUPPORTED_PROTOCOL, "unsupported protocol")          \
_(OUT2IN_PACKETS, "good out2in packets processed")       \
_(NO_TRANSLATION, "no translation")                      \
_(UNKNOWN, "unknown")                                    \
_(DROP_FRAGMENT, "drop fragment")                        \
_(MAX_REASS, "maximum reassemblies exceeded")            \
_(MAX_FRAG, "maximum fragments per reassembly exceeded") \
_(TCP_PACKETS, "TCP packets")                            \
_(UDP_PACKETS, "UDP packets")                            \
_(ICMP_PACKETS, "ICMP packets")                          \
_(OTHER_PACKETS, "other protocol packets")               \
_(FRAGMENTS, "fragments")                                \
_(CACHED_FRAGMENTS, "cached fragments")                  \
_(PROCESSED_FRAGMENTS, "processed fragments")


typedef enum
{
#define _(sym,str) NAT64_OUT2IN_ERROR_##sym,
  foreach_nat64_out2in_error
#undef _
    NAT64_OUT2IN_N_ERROR,
} nat64_out2in_error_t;

static char *nat64_out2in_error_strings[] = {
#define _(sym,string) string,
  foreach_nat64_out2in_error
#undef _
};

typedef enum
{
  NAT64_OUT2IN_NEXT_IP6_LOOKUP,
  NAT64_OUT2IN_NEXT_IP4_LOOKUP,
  NAT64_OUT2IN_NEXT_DROP,
  NAT64_OUT2IN_NEXT_REASS,
  NAT64_OUT2IN_N_NEXT,
} nat64_out2in_next_t;

typedef struct nat64_out2in_set_ctx_t_
{
  vlib_buffer_t *b;
  vlib_main_t *vm;
  u32 thread_index;
} nat64_out2in_set_ctx_t;

static int
nat64_out2in_tcp_udp_set_cb (ip4_header_t * ip4, ip6_header_t * ip6,
                             void *arg)
{
  nat64_main_t *nm = &nat64_main;
  nat64_out2in_set_ctx_t *ctx = arg;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t saddr, daddr;
  ip6_address_t ip6_saddr;
  udp_header_t *udp = ip4_next_header (ip4);
  tcp_header_t *tcp = ip4_next_header (ip4);
  u8 proto = ip4->protocol;
  u16 dport = udp->dst_port;
  u16 sport = udp->src_port;
  u32 sw_if_index, fib_index;
  u16 *checksum;
  ip_csum_t csum;
  nat64_db_t *db = &nm->db[ctx->thread_index];

  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
  fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);

  clib_memset (&saddr, 0, sizeof (saddr));
  saddr.ip4.as_u32 = ip4->src_address.as_u32;
  clib_memset (&daddr, 0, sizeof (daddr));
  daddr.ip4.as_u32 = ip4->dst_address.as_u32;

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

      if (!bibe)
        return -1;

      nat64_compose_ip6 (&ip6_saddr, &ip4->src_address, bibe->fib_index);
      ste =
        nat64_db_st_entry_create (ctx->thread_index, db, bibe, &ip6_saddr,
                                  &saddr.ip4, sport);

      if (!ste)
        return -1;

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

  ip6->src_address.as_u64[0] = ste->in_r_addr.as_u64[0];
  ip6->src_address.as_u64[1] = ste->in_r_addr.as_u64[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];
  udp->dst_port = bibe->in_port;

  if (proto == IP_PROTOCOL_UDP)
    checksum = &udp->checksum;
  else
    {
      checksum = &tcp->checksum;
      nat64_tcp_session_set_state (ste, tcp, 0);
    }

  csum = ip_csum_sub_even (*checksum, dport);
  csum = ip_csum_add_even (csum, udp->dst_port);
  *checksum = ip_csum_fold (csum);

  vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;

  nat64_session_reset_timeout (ste, ctx->vm);

  return 0;
}

static int
nat64_out2in_icmp_set_cb (ip4_header_t * ip4, ip6_header_t * ip6, void *arg)
{
  nat64_main_t *nm = &nat64_main;
  nat64_out2in_set_ctx_t *ctx = arg;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t saddr, daddr;
  ip6_address_t ip6_saddr;
  u32 sw_if_index, fib_index;
  icmp46_header_t *icmp = ip4_next_header (ip4);
  nat64_db_t *db = &nm->db[ctx->thread_index];

  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
  fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);

  clib_memset (&saddr, 0, sizeof (saddr));
  saddr.ip4.as_u32 = ip4->src_address.as_u32;
  clib_memset (&daddr, 0, sizeof (daddr));
  daddr.ip4.as_u32 = ip4->dst_address.as_u32;

  if (icmp->type == ICMP6_echo_request || icmp->type == ICMP6_echo_reply)
    {
      u16 out_id = ((u16 *) (icmp))[2];
      ste =
        nat64_db_st_entry_find (db, &daddr, &saddr, out_id, 0,
                                IP_PROTOCOL_ICMP, fib_index, 0);

      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, &daddr, out_id,
                                     IP_PROTOCOL_ICMP, fib_index, 0);
          if (!bibe)
            return -1;

          nat64_compose_ip6 (&ip6_saddr, &ip4->src_address, bibe->fib_index);
          ste =
            nat64_db_st_entry_create (ctx->thread_index, db,
                                      bibe, &ip6_saddr, &saddr.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);

      ip6->src_address.as_u64[0] = ste->in_r_addr.as_u64[0];
      ip6->src_address.as_u64[1] = ste->in_r_addr.as_u64[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];
      ((u16 *) (icmp))[2] = bibe->in_port;

      vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
    }
  else
    {
      ip6_header_t *inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8);

      nat64_compose_ip6 (&ip6->src_address, &ip4->src_address,
                         vnet_buffer (ctx->b)->sw_if_index[VLIB_TX]);
      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];
    }

  return 0;
}

static int
nat64_out2in_inner_icmp_set_cb (ip4_header_t * ip4, ip6_header_t * ip6,
                                void *arg)
{
  nat64_main_t *nm = &nat64_main;
  nat64_out2in_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;
  u8 proto = ip4->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);

  clib_memset (&saddr, 0, sizeof (saddr));
  saddr.ip4.as_u32 = ip4->src_address.as_u32;
  clib_memset (&daddr, 0, sizeof (daddr));
  daddr.ip4.as_u32 = ip4->dst_address.as_u32;

  if (proto == IP_PROTOCOL_ICMP6)
    {
      icmp46_header_t *icmp = ip4_next_header (ip4);
      u16 out_id = ((u16 *) (icmp))[2];
      proto = IP_PROTOCOL_ICMP;

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

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

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

      ip6->dst_address.as_u64[0] = ste->in_r_addr.as_u64[0];
      ip6->dst_address.as_u64[1] = ste->in_r_addr.as_u64[1];
      ip6->src_address.as_u64[0] = bibe->in_addr.as_u64[0];
      ip6->src_address.as_u64[1] = bibe->in_addr.as_u64[1];
      ((u16 *) (icmp))[2] = bibe->in_port;

      vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
    }
  else
    {
      udp_header_t *udp = ip4_next_header (ip4);
      tcp_header_t *tcp = ip4_next_header (ip4);
      u16 dport = udp->dst_port;
      u16 sport = udp->src_port;
      u16 *checksum;
      ip_csum_t csum;

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

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

      nat64_compose_ip6 (&ip6->dst_address, &daddr.ip4, bibe->fib_index);
      ip6->src_address.as_u64[0] = bibe->in_addr.as_u64[0];
      ip6->src_address.as_u64[1] = bibe->in_addr.as_u64[1];
      udp->src_port = bibe->in_port;

      if (proto == IP_PROTOCOL_UDP)
        checksum = &udp->checksum;
      else
        checksum = &tcp->checksum;
      if (*checksum)
        {
          csum = ip_csum_sub_even (*checksum, sport);
          csum = ip_csum_add_even (csum, udp->src_port);
          *checksum = ip_csum_fold (csum);
        }

      vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
    }

  return 0;
}

static int
nat64_out2in_unk_proto_set_cb (ip4_header_t * ip4, ip6_header_t * ip6,
                               void *arg)
{
  nat64_main_t *nm = &nat64_main;
  nat64_out2in_set_ctx_t *ctx = arg;
  nat64_db_bib_entry_t *bibe;
  nat64_db_st_entry_t *ste;
  ip46_address_t saddr, daddr;
  ip6_address_t ip6_saddr;
  u32 sw_if_index, fib_index;
  u8 proto = ip4->protocol;
  nat64_db_t *db = &nm->db[ctx->thread_index];

  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
  fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);

  clib_memset (&saddr, 0, sizeof (saddr));
  saddr.ip4.as_u32 = ip4->src_address.as_u32;
  clib_memset (&daddr, 0, sizeof (daddr));
  daddr.ip4.as_u32 = ip4->dst_address.as_u32;

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

      if (!bibe)
        return -1;

      nat64_compose_ip6 (&ip6_saddr, &ip4->src_address, bibe->fib_index);
      ste = nat64_db_st_entry_create (ctx->thread_index, db,
                                      bibe, &ip6_saddr, &saddr.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);

  ip6->src_address.as_u64[0] = ste->in_r_addr.as_u64[0];
  ip6->src_address.as_u64[1] = ste->in_r_addr.as_u64[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];

  vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;

  return 0;
}

VLIB_NODE_FN (nat64_out2in_node) (vlib_main_t * vm,
                                  vlib_node_runtime_t * node,
                                  vlib_frame_t * frame)
{
  u32 n_left_from, *from, *to_next;
  nat64_out2in_next_t next_index;
  nat64_main_t *nm = &nat64_main;
  u32 pkts_processed = 0;
  u32 thread_index = vm->thread_index;
  u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
    0, fragments = 0;

  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 *ip40;
          u32 proto0;
          nat64_out2in_set_ctx_t ctx0;
          udp_header_t *udp0;

          /* 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);
          ip40 = vlib_buffer_get_current (b0);

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

          next0 = NAT64_OUT2IN_NEXT_IP6_LOOKUP;

          proto0 = ip_proto_to_snat_proto (ip40->protocol);

          if (PREDICT_FALSE (proto0 == ~0))
            {
              if (ip4_to_ip6 (b0, nat64_out2in_unk_proto_set_cb, &ctx0))
                {
                  next0 = NAT64_OUT2IN_NEXT_DROP;
                  b0->error = node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
                }
              other_packets++;
              goto trace0;
            }

          if (PREDICT_FALSE (ip4_is_fragment (ip40)))
            {
              next0 = NAT64_OUT2IN_NEXT_REASS;
              fragments++;
              goto trace0;
            }

          if (proto0 == SNAT_PROTOCOL_ICMP)
            {
              icmp_packets++;
              if (icmp_to_icmp6
                  (b0, nat64_out2in_icmp_set_cb, &ctx0,
                   nat64_out2in_inner_icmp_set_cb, &ctx0))
                {
                  next0 = NAT64_OUT2IN_NEXT_DROP;
                  b0->error = node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
                  goto trace0;
                }
            }
          else
            {
              if (proto0 == SNAT_PROTOCOL_TCP)
                tcp_packets++;
              else
                udp_packets++;

              if (ip4_to_ip6_tcp_udp (b0, nat64_out2in_tcp_udp_set_cb, &ctx0))
                {
                  udp0 = ip4_next_header (ip40);
                  /*
                   * Send DHCP packets to the ipv4 stack, or we won't
                   * be able to use dhcp client on the outside interface
                   */
                  if ((proto0 == SNAT_PROTOCOL_UDP)
                      && (udp0->dst_port ==
                          clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_client)))
                    {
                      next0 = NAT64_OUT2IN_NEXT_IP4_LOOKUP;
                      goto trace0;
                    }
                  next0 = NAT64_OUT2IN_NEXT_DROP;
                  b0->error = node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
                  goto trace0;
                }
            }

        trace0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat64_out2in_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;
            }

          pkts_processed += next0 == NAT64_OUT2IN_NEXT_IP6_LOOKUP;

          /* 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);
    }
  vlib_node_increment_counter (vm, nm->out2in_node_index,
                               NAT64_OUT2IN_ERROR_OUT2IN_PACKETS,
                               pkts_processed);
  vlib_node_increment_counter (vm, nm->out2in_node_index,
                               NAT64_OUT2IN_ERROR_TCP_PACKETS, tcp_packets);
  vlib_node_increment_counter (vm, nm->out2in_node_index,
                               NAT64_OUT2IN_ERROR_UDP_PACKETS, udp_packets);
  vlib_node_increment_counter (vm, nm->out2in_node_index,
                               NAT64_OUT2IN_ERROR_ICMP_PACKETS, icmp_packets);
  vlib_node_increment_counter (vm, nm->out2in_node_index,
                               NAT64_OUT2IN_ERROR_OTHER_PACKETS,
                               other_packets);
  vlib_node_increment_counter (vm, nm->out2in_node_index,
                               NAT64_OUT2IN_ERROR_FRAGMENTS, fragments);

  return frame->n_vectors;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat64_out2in_node) = {
  .name = "nat64-out2in",
  .vector_size = sizeof (u32),
  .format_trace = format_nat64_out2in_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat64_out2in_error_strings),
  .error_strings = nat64_out2in_error_strings,
  .n_next_nodes = NAT64_OUT2IN_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
    [NAT64_OUT2IN_NEXT_DROP] = "error-drop",
    [NAT64_OUT2IN_NEXT_IP6_LOOKUP] = "ip6-lookup",
    [NAT64_OUT2IN_NEXT_IP4_LOOKUP] = "ip4-lookup",
    [NAT64_OUT2IN_NEXT_REASS] = "nat64-out2in-reass",
  },
};
/* *INDENT-ON* */

typedef struct nat64_out2in_frag_set_ctx_t_
{
  vlib_main_t *vm;
  vlib_buffer_t *b;
  u32 sess_index;
  u32 thread_index;
  u8 proto;
  u8 first_frag;
} nat64_out2in_frag_set_ctx_t;

static int
nat64_out2in_frag_set_cb (ip4_header_t * ip4, ip6_header_t * ip6, void *arg)
{
  nat64_main_t *nm = &nat64_main;
  nat64_out2in_frag_set_ctx_t *ctx = arg;
  nat64_db_st_entry_t *ste;
  nat64_db_bib_entry_t *bibe;
  udp_header_t *udp = ip4_next_header (ip4);
  ip_csum_t csum;
  u16 *checksum;
  nat64_db_t *db = &nm->db[ctx->thread_index];

  ste = nat64_db_st_entry_by_index (db, ctx->proto, ctx->sess_index);
  if (!ste)
    return -1;

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

  if (ctx->first_frag)
    {
      udp->dst_port = bibe->in_port;

      if (ip4->protocol == IP_PROTOCOL_UDP)
        {
          checksum = &udp->checksum;

          if (!checksum)
            {
              u16 udp_len =
                clib_host_to_net_u16 (ip4->length) - sizeof (*ip4);
              csum = ip_incremental_checksum (0, udp, udp_len);
              csum =
                ip_csum_with_carry (csum, clib_host_to_net_u16 (udp_len));
              csum =
                ip_csum_with_carry (csum,
                                    clib_host_to_net_u16 (IP_PROTOCOL_UDP));
              csum = ip_csum_with_carry (csum, ste->in_r_addr.as_u64[0]);
              csum = ip_csum_with_carry (csum, ste->in_r_addr.as_u64[1]);
              csum = ip_csum_with_carry (csum, bibe->in_addr.as_u64[0]);
              csum = ip_csum_with_carry (csum, bibe->in_addr.as_u64[1]);
              *checksum = ~ip_csum_fold (csum);
            }
          else
            {
              csum = ip_csum_sub_even (*checksum, bibe->out_addr.as_u32);
              csum = ip_csum_sub_even (csum, ste->out_r_addr.as_u32);
              csum = ip_csum_sub_even (csum, bibe->out_port);
              csum = ip_csum_add_even (csum, ste->in_r_addr.as_u64[0]);
              csum = ip_csum_add_even (csum, ste->in_r_addr.as_u64[1]);
              csum = ip_csum_add_even (csum, bibe->in_addr.as_u64[0]);
              csum = ip_csum_add_even (csum, bibe->in_addr.as_u64[1]);
              csum = ip_csum_add_even (csum, bibe->in_port);
              *checksum = ip_csum_fold (csum);
            }
        }
      else
        {
          tcp_header_t *tcp = ip4_next_header (ip4);
          nat64_tcp_session_set_state (ste, tcp, 0);
          checksum = &tcp->checksum;
          csum = ip_csum_sub_even (*checksum, bibe->out_addr.as_u32);
          csum = ip_csum_sub_even (csum, ste->out_r_addr.as_u32);
          csum = ip_csum_sub_even (csum, bibe->out_port);
          csum = ip_csum_add_even (csum, ste->in_r_addr.as_u64[0]);
          csum = ip_csum_add_even (csum, ste->in_r_addr.as_u64[1]);
          csum = ip_csum_add_even (csum, bibe->in_addr.as_u64[0]);
          csum = ip_csum_add_even (csum, bibe->in_addr.as_u64[1]);
          csum = ip_csum_add_even (csum, bibe->in_port);
          *checksum = ip_csum_fold (csum);
        }

    }

  ip6->src_address.as_u64[0] = ste->in_r_addr.as_u64[0];
  ip6->src_address.as_u64[1] = ste->in_r_addr.as_u64[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];

  vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;

  nat64_session_reset_timeout (ste, ctx->vm);

  return 0;
}

VLIB_NODE_FN (nat64_out2in_reass_node) (vlib_main_t * vm,
                                        vlib_node_runtime_t * node,
                                        vlib_frame_t * frame)
{
  u32 n_left_from, *from, *to_next;
  nat64_out2in_next_t next_index;
  u32 pkts_processed = 0, cached_fragments = 0;
  u32 *fragments_to_drop = 0;
  u32 *fragments_to_loopback = 0;
  nat64_main_t *nm = &nat64_main;
  u32 thread_index = vm->thread_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 *ip40;
          u8 cached0 = 0;
          u32 sw_if_index0, fib_index0;
          udp_header_t *udp0;
          nat_reass_ip4_t *reass0;
          ip46_address_t saddr0, daddr0;
          nat64_db_st_entry_t *ste0;
          nat64_db_bib_entry_t *bibe0;
          ip6_address_t ip6_saddr0;
          nat64_out2in_frag_set_ctx_t ctx0;
          nat64_db_t *db = &nm->db[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 = NAT64_OUT2IN_NEXT_IP6_LOOKUP;

          sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
          fib_index0 =
            fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
                                                 sw_if_index0);

          ctx0.thread_index = thread_index;

          if (PREDICT_FALSE (nat_reass_is_drop_frag (1)))
            {
              next0 = NAT64_OUT2IN_NEXT_DROP;
              b0->error = node->errors[NAT64_OUT2IN_ERROR_DROP_FRAGMENT];
              goto trace0;
            }

          ip40 = vlib_buffer_get_current (b0);

          if (PREDICT_FALSE (!(ip40->protocol == IP_PROTOCOL_TCP
                               || ip40->protocol == IP_PROTOCOL_UDP)))
            {
              next0 = NAT64_OUT2IN_NEXT_DROP;
              b0->error = node->errors[NAT64_OUT2IN_ERROR_DROP_FRAGMENT];
              goto trace0;
            }

          udp0 = ip4_next_header (ip40);

          reass0 = nat_ip4_reass_find_or_create (ip40->src_address,
                                                 ip40->dst_address,
                                                 ip40->fragment_id,
                                                 ip40->protocol,
                                                 1, &fragments_to_drop);

          if (PREDICT_FALSE (!reass0))
            {
              next0 = NAT64_OUT2IN_NEXT_DROP;
              b0->error = node->errors[NAT64_OUT2IN_ERROR_MAX_REASS];
              goto trace0;
            }

          if (PREDICT_FALSE (ip4_is_first_fragment (ip40)))
            {
              ctx0.first_frag = 1;

              clib_memset (&saddr0, 0, sizeof (saddr0));
              saddr0.ip4.as_u32 = ip40->src_address.as_u32;
              clib_memset (&daddr0, 0, sizeof (daddr0));
              daddr0.ip4.as_u32 = ip40->dst_address.as_u32;

              ste0 =
                nat64_db_st_entry_find (db, &daddr0, &saddr0,
                                        udp0->dst_port, udp0->src_port,
                                        ip40->protocol, fib_index0, 0);
              if (!ste0)
                {
                  bibe0 =
                    nat64_db_bib_entry_find (db, &daddr0, udp0->dst_port,
                                             ip40->protocol, fib_index0, 0);
                  if (!bibe0)
                    {
                      next0 = NAT64_OUT2IN_NEXT_DROP;
                      b0->error =
                        node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
                      goto trace0;
                    }

                  nat64_compose_ip6 (&ip6_saddr0, &ip40->src_address,
                                     bibe0->fib_index);
                  ste0 =
                    nat64_db_st_entry_create (thread_index,
                                              db, bibe0, &ip6_saddr0,
                                              &saddr0.ip4, udp0->src_port);

                  if (!ste0)
                    {
                      next0 = NAT64_OUT2IN_NEXT_DROP;
                      b0->error =
                        node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
                      goto trace0;
                    }

                  vlib_set_simple_counter (&nm->total_sessions, thread_index,
                                           0, db->st.st_entries_num);
                }
              reass0->sess_index = nat64_db_st_entry_get_index (db, ste0);
              reass0->thread_index = thread_index;

              nat_ip4_reass_get_frags (reass0, &fragments_to_loopback);
            }
          else
            {
              ctx0.first_frag = 0;

              if (PREDICT_FALSE (reass0->sess_index == (u32) ~ 0))
                {
                  if (nat_ip4_reass_add_fragment
                      (thread_index, reass0, bi0, &fragments_to_drop))
                    {
                      b0->error = node->errors[NAT64_OUT2IN_ERROR_MAX_FRAG];
                      next0 = NAT64_OUT2IN_NEXT_DROP;
                      goto trace0;
                    }
                  cached0 = 1;
                  goto trace0;
                }
            }

          ctx0.sess_index = reass0->sess_index;
          ctx0.proto = ip40->protocol;
          ctx0.vm = vm;
          ctx0.b = b0;

          if (ip4_to_ip6_fragmented (b0, nat64_out2in_frag_set_cb, &ctx0))
            {
              next0 = NAT64_OUT2IN_NEXT_DROP;
              b0->error = node->errors[NAT64_OUT2IN_ERROR_UNKNOWN];
              goto trace0;
            }

        trace0:
          if (PREDICT_FALSE
              ((node->flags & VLIB_NODE_FLAG_TRACE)
               && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat64_out2in_reass_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->cached = cached0;
              t->sw_if_index = sw_if_index0;
              t->next_index = next0;
            }

          if (cached0)
            {
              n_left_to_next++;
              to_next--;
              cached_fragments++;
            }
          else
            {
              pkts_processed += next0 != NAT64_OUT2IN_NEXT_DROP;

              /* 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);
            }

          if (n_left_from == 0 && vec_len (fragments_to_loopback))
            {
              from = vlib_frame_vector_args (frame);
              u32 len = vec_len (fragments_to_loopback);
              if (len <= VLIB_FRAME_SIZE)
                {
                  clib_memcpy_fast (from, fragments_to_loopback,
                                    sizeof (u32) * len);
                  n_left_from = len;
                  vec_reset_length (fragments_to_loopback);
                }
              else
                {
                  clib_memcpy_fast (from, fragments_to_loopback +
                                    (len - VLIB_FRAME_SIZE),
                                    sizeof (u32) * VLIB_FRAME_SIZE);
                  n_left_from = VLIB_FRAME_SIZE;
                  _vec_len (fragments_to_loopback) = len - VLIB_FRAME_SIZE;
                }
            }
        }

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

  vlib_node_increment_counter (vm, nm->out2in_reass_node_index,
                               NAT64_OUT2IN_ERROR_PROCESSED_FRAGMENTS,
                               pkts_processed);
  vlib_node_increment_counter (vm, nm->out2in_reass_node_index,
                               NAT64_OUT2IN_ERROR_CACHED_FRAGMENTS,
                               cached_fragments);

  nat_send_all_to_node (vm, fragments_to_drop, node,
                        &node->errors[NAT64_OUT2IN_ERROR_DROP_FRAGMENT],
                        NAT64_OUT2IN_NEXT_DROP);

  vec_free (fragments_to_drop);
  vec_free (fragments_to_loopback);
  return frame->n_vectors;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat64_out2in_reass_node) = {
  .name = "nat64-out2in-reass",
  .vector_size = sizeof (u32),
  .format_trace = format_nat64_out2in_reass_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat64_out2in_error_strings),
  .error_strings = nat64_out2in_error_strings,
  .n_next_nodes = NAT64_OUT2IN_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
    [NAT64_OUT2IN_NEXT_DROP] = "error-drop",
    [NAT64_OUT2IN_NEXT_IP6_LOOKUP] = "ip6-lookup",
    [NAT64_OUT2IN_NEXT_IP4_LOOKUP] = "ip4-lookup",
    [NAT64_OUT2IN_NEXT_REASS] = "nat64-out2in-reass",
  },
};
/* *INDENT-ON* */

#define foreach_nat64_out2in_handoff_error                       \
_(CONGESTION_DROP, "congestion drop")                            \
_(SAME_WORKER, "same worker")                                    \
_(DO_HANDOFF, "do handoff")

typedef enum
{
#define _(sym,str) NAT64_OUT2IN_HANDOFF_ERROR_##sym,
  foreach_nat64_out2in_handoff_error
#undef _
    NAT64_OUT2IN_HANDOFF_N_ERROR,
} nat64_out2in_handoff_error_t;

static char *nat64_out2in_handoff_error_strings[] = {
#define _(sym,string) string,
  foreach_nat64_out2in_handoff_error
#undef _
};

typedef struct
{
  u32 next_worker_index;
} nat64_out2in_handoff_trace_t;

static u8 *
format_nat64_out2in_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_out2in_handoff_trace_t *t =
    va_arg (*args, nat64_out2in_handoff_trace_t *);

  s =
    format (s, "NAT64-OUT2IN-HANDOFF: next-worker %d", t->next_worker_index);

  return s;
}

VLIB_NODE_FN (nat64_out2in_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_out2in_index;

  while (n_left_from > 0)
    {
      ip4_header_t *ip0;

      ip0 = vlib_buffer_get_current (b[0]);
      ti[0] = nat64_get_worker_out2in (ip0);

      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_out2in_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_OUT2IN_HANDOFF_ERROR_CONGESTION_DROP,
                                 frame->n_vectors - n_enq);
  vlib_node_increment_counter (vm, node->node_index,
                               NAT64_OUT2IN_HANDOFF_ERROR_SAME_WORKER,
                               same_worker);
  vlib_node_increment_counter (vm, node->node_index,
                               NAT64_OUT2IN_HANDOFF_ERROR_DO_HANDOFF,
                               do_handoff);

  return frame->n_vectors;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat64_out2in_handoff_node) = {
  .name = "nat64-out2in-handoff",
  .vector_size = sizeof (u32),
  .format_trace = format_nat64_out2in_handoff_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(nat64_out2in_handoff_error_strings),
  .error_strings = nat64_out2in_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:
 */