decap.c

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/*
 * decap.c: vxlan tunnel decap packet processing
 *
 * Copyright (c) 2013 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/pg/pg.h>
#include <vnet/vxlan/vxlan.h>

vlib_node_registration_t vxlan4_input_node;
vlib_node_registration_t vxlan6_input_node;

typedef struct {
  u32 next_index;
  u32 tunnel_index;
  u32 error;
  u32 vni;
} vxlan_rx_trace_t;

static u8 * format_vxlan_rx_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 *);
  vxlan_rx_trace_t * t = va_arg (*args, vxlan_rx_trace_t *);

  if (t->tunnel_index != ~0)
    {
      s = format (s, "VXLAN decap from vxlan_tunnel%d vni %d next %d error %d",
                  t->tunnel_index, t->vni, t->next_index, t->error);
    }
  else
    {
      s = format (s, "VXLAN decap error - tunnel for vni %d does not exist",
                  t->vni);
    }
  return s;
}

always_inline u32
buf_fib_index (vlib_buffer_t *b, u32 is_ip4)
{
  u32 sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_TX];
  if (sw_if_index != (u32) ~ 0)
    return sw_if_index;

  u32 * fib_index_by_sw_if_index = is_ip4 ?
    ip4_main.fib_index_by_sw_if_index : ip6_main.fib_index_by_sw_if_index;
  sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];

  return vec_elt (fib_index_by_sw_if_index, sw_if_index);
}

typedef vxlan4_tunnel_key_t last_tunnel_cache4;

always_inline vxlan_tunnel_t *
vxlan4_find_tunnel (vxlan_main_t * vxm, last_tunnel_cache4 * cache,
                    u32 fib_index, ip4_header_t * ip4_0, vxlan_header_t * vxlan0,
                    vxlan_tunnel_t ** stats_t0)
{
  /* Make sure VXLAN tunnel exist according to packet SIP and VNI */
  vxlan4_tunnel_key_t key4 = {
    .key = {
      [0] = ip4_0->src_address.as_u32,
      [1] = (((u64) fib_index) << 32) | vxlan0->vni_reserved,
    }
  };

  if (PREDICT_FALSE (clib_bihash_key_compare_16_8 (key4.key, cache->key) == 0))
  {
    int rv = clib_bihash_search_inline_16_8 (&vxm->vxlan4_tunnel_by_key, &key4);
    if (PREDICT_FALSE (rv != 0))
      return 0;

    *cache = key4;
  }
  vxlan_tunnel_t * t0 = pool_elt_at_index (vxm->tunnels, cache->value);

  /* Validate VXLAN tunnel SIP against packet DIP */
  if (PREDICT_TRUE (ip4_0->dst_address.as_u32 == t0->src.ip4.as_u32))
    *stats_t0 = t0;
  else
  {
    /* try multicast */
    if (PREDICT_TRUE (!ip4_address_is_multicast (&ip4_0->dst_address)))
      return 0;

    key4.key[0] = ip4_0->dst_address.as_u32;
    /* Make sure mcast VXLAN tunnel exist by packet DIP and VNI */
    int rv = clib_bihash_search_inline_16_8 (&vxm->vxlan4_tunnel_by_key, &key4);
    if (PREDICT_FALSE (rv != 0))
      return 0;

    *stats_t0 = pool_elt_at_index (vxm->tunnels, key4.value);
  }

  return t0;
}

typedef vxlan6_tunnel_key_t last_tunnel_cache6;

always_inline vxlan_tunnel_t *
vxlan6_find_tunnel (vxlan_main_t * vxm, last_tunnel_cache6 * cache,
                    u32 fib_index, ip6_header_t * ip6_0, vxlan_header_t * vxlan0,
                    vxlan_tunnel_t ** stats_t0)
{
  /* Make sure VXLAN tunnel exist according to packet SIP and VNI */

  vxlan6_tunnel_key_t key6 = {
    .key = {
      [0] = ip6_0->src_address.as_u64[0],
      [1] = ip6_0->src_address.as_u64[1],
      [2] = (((u64) fib_index) << 32) | vxlan0->vni_reserved,
    }
  };

  if (PREDICT_FALSE (clib_bihash_key_compare_24_8 (key6.key, cache->key) == 0))
  {
    int rv = clib_bihash_search_inline_24_8 (&vxm->vxlan6_tunnel_by_key, &key6);
    if (PREDICT_FALSE (rv != 0))
      return 0;

    *cache = key6;
  }
  vxlan_tunnel_t * t0 = pool_elt_at_index (vxm->tunnels, cache->value);

  /* Validate VXLAN tunnel SIP against packet DIP */
  if (PREDICT_TRUE (ip6_address_is_equal (&ip6_0->dst_address, &t0->src.ip6)))
    *stats_t0 = t0;
  else
  {
    /* try multicast */
    if (PREDICT_TRUE (!ip6_address_is_multicast (&ip6_0->dst_address)))
      return 0;

    /* Make sure mcast VXLAN tunnel exist by packet DIP and VNI */
    key6.key[0] = ip6_0->dst_address.as_u64[0];
    key6.key[1] = ip6_0->dst_address.as_u64[1];
    int rv = clib_bihash_search_inline_24_8 (&vxm->vxlan6_tunnel_by_key, &key6);
    if (PREDICT_FALSE (rv != 0))
      return 0;

    *stats_t0 = pool_elt_at_index (vxm->tunnels, key6.value);
  }

  return t0;
}

always_inline uword
vxlan_input (vlib_main_t * vm,
             vlib_node_runtime_t * node,
             vlib_frame_t * from_frame,
             u32 is_ip4)
{
  vxlan_main_t * vxm = &vxlan_main;
  vnet_main_t * vnm = vxm->vnet_main;
  vnet_interface_main_t * im = &vnm->interface_main;
  vlib_combined_counter_main_t * rx_counter = im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_RX;
  vlib_combined_counter_main_t * drop_counter = im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_DROP;
  last_tunnel_cache4 last4;
  last_tunnel_cache6 last6;
  u32 pkts_decapsulated = 0;
  u32 thread_index = vlib_get_thread_index();

  if (is_ip4)
    memset (&last4, 0xff, sizeof last4);
  else
    memset (&last6, 0xff, sizeof last6);

  u32 next_index = node->cached_next_index;

  u32 * from = vlib_frame_vector_args (from_frame);
  u32 n_left_from = from_frame->n_vectors;

  while (n_left_from > 0)
    {
      u32 * to_next, n_left_to_next;
      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from >= 4 && n_left_to_next >= 2)
        {
          /* Prefetch next iteration. */
          {
            vlib_buffer_t * p2, * p3;

            p2 = vlib_get_buffer (vm, from[2]);
            p3 = vlib_get_buffer (vm, from[3]);

            vlib_prefetch_buffer_header (p2, LOAD);
            vlib_prefetch_buffer_header (p3, LOAD);

            CLIB_PREFETCH (p2->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
            CLIB_PREFETCH (p3->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
          }

          u32 bi0 = to_next[0] = from[0];
          u32 bi1 = to_next[1] = from[1];
          from += 2;
          to_next += 2;
          n_left_to_next -= 2;
          n_left_from -= 2;

          vlib_buffer_t * b0, * b1;
          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);

          /* udp leaves current_data pointing at the vxlan header */
          void * cur0 = vlib_buffer_get_current (b0);
          void * cur1 = vlib_buffer_get_current (b1);
          vxlan_header_t * vxlan0 = cur0;
          vxlan_header_t * vxlan1 = cur1;

          ip4_header_t * ip4_0, * ip4_1;
          ip6_header_t * ip6_0, * ip6_1;
          if (is_ip4) {
            ip4_0 = cur0 - sizeof(udp_header_t) - sizeof(ip4_header_t);
            ip4_1 = cur1 - sizeof(udp_header_t) - sizeof(ip4_header_t);
          } else {
            ip6_0 = cur0 - sizeof(udp_header_t) - sizeof(ip6_header_t);
            ip6_1 = cur1 - sizeof(udp_header_t) - sizeof(ip6_header_t);
          }

          /* pop vxlan */
          vlib_buffer_advance (b0, sizeof *vxlan0);
          vlib_buffer_advance (b1, sizeof *vxlan1);

          u32 fi0 = buf_fib_index(b0, is_ip4);
          u32 fi1 = buf_fib_index(b1, is_ip4);

          vxlan_tunnel_t * t0, * stats_t0;
          vxlan_tunnel_t * t1, * stats_t1;
          if (is_ip4)
          {
            t0 = vxlan4_find_tunnel (vxm, &last4, fi0, ip4_0, vxlan0, &stats_t0);
            t1 = vxlan4_find_tunnel (vxm, &last4, fi1, ip4_1, vxlan1, &stats_t1);
          }
          else
          {
            t0 = vxlan6_find_tunnel (vxm, &last6, fi0, ip6_0, vxlan0, &stats_t0);
            t1 = vxlan6_find_tunnel (vxm, &last6, fi1, ip6_1, vxlan1, &stats_t1);
          }

          u32 len0 = vlib_buffer_length_in_chain (vm, b0);
          u32 len1 = vlib_buffer_length_in_chain (vm, b1);

          u32 next0, next1;
          u8 error0 = 0, error1 = 0;
          /* Validate VXLAN tunnel encap-fib index agaist packet */
          if (PREDICT_FALSE (t0 == 0 || vxlan0->flags != VXLAN_FLAGS_I))
            {
              next0 = VXLAN_INPUT_NEXT_DROP;

              if (t0 != 0 && vxlan0->flags != VXLAN_FLAGS_I)
                {
                  error0 = VXLAN_ERROR_BAD_FLAGS;
                  vlib_increment_combined_counter
                    (drop_counter, thread_index, stats_t0->sw_if_index, 1, len0);
                }
              else
                error0 = VXLAN_ERROR_NO_SUCH_TUNNEL;
              b0->error = node->errors[error0];
            }
          else
            {
              next0 = t0->decap_next_index;

              /* Required to make the l2 tag push / pop code work on l2 subifs */
              if (PREDICT_TRUE(next0 == VXLAN_INPUT_NEXT_L2_INPUT))
                vnet_update_l2_len (b0);

              /* Set packet input sw_if_index to unicast VXLAN tunnel for learning */
              vnet_buffer(b0)->sw_if_index[VLIB_RX] = t0->sw_if_index;
              vlib_increment_combined_counter
                (rx_counter, thread_index, stats_t0->sw_if_index, 1, len0);
              pkts_decapsulated++;
            }

          /* Validate VXLAN tunnel encap-fib index agaist packet */
          if (PREDICT_FALSE (t1 == 0 || vxlan1->flags != VXLAN_FLAGS_I))
            {
              next1 = VXLAN_INPUT_NEXT_DROP;

              if (t1 != 0 && vxlan1->flags != VXLAN_FLAGS_I)
                {
                  error1 = VXLAN_ERROR_BAD_FLAGS;
                  vlib_increment_combined_counter
                    (drop_counter, thread_index, stats_t1->sw_if_index, 1, len1);
                }
              else
                error1 = VXLAN_ERROR_NO_SUCH_TUNNEL;
              b1->error = node->errors[error1];
            }
          else
            {
              next1 = t1->decap_next_index;

              /* Required to make the l2 tag push / pop code work on l2 subifs */
              if (PREDICT_TRUE(next1 == VXLAN_INPUT_NEXT_L2_INPUT))
                vnet_update_l2_len (b1);

              /* Set packet input sw_if_index to unicast VXLAN tunnel for learning */
              vnet_buffer(b1)->sw_if_index[VLIB_RX] = t1->sw_if_index;
              pkts_decapsulated++;

              vlib_increment_combined_counter
                (rx_counter, thread_index, stats_t1->sw_if_index, 1, len1);
            }

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
            {
              vxlan_rx_trace_t *tr = vlib_add_trace (vm, node, b0, sizeof (*tr));
              tr->next_index = next0;
              tr->error = error0;
              tr->tunnel_index = t0 == 0 ? ~0 : t0 - vxm->tunnels;
              tr->vni = vnet_get_vni (vxlan0);
            }
          if (PREDICT_FALSE(b1->flags & VLIB_BUFFER_IS_TRACED))
            {
              vxlan_rx_trace_t *tr = vlib_add_trace (vm, node, b1, sizeof (*tr));
              tr->next_index = next1;
              tr->error = error1;
              tr->tunnel_index = t1 == 0 ? ~0 : t1 - vxm->tunnels;
              tr->vni = vnet_get_vni (vxlan1);
            }

          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, bi1, next0, next1);
        }

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0 = to_next[0] = from[0];
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          vlib_buffer_t * b0 = vlib_get_buffer (vm, bi0);

          /* udp leaves current_data pointing at the vxlan header */
          void * cur0 = vlib_buffer_get_current (b0);
          vxlan_header_t * vxlan0 = cur0;
          ip4_header_t * ip4_0;
          ip6_header_t * ip6_0;
          if (is_ip4)
            ip4_0 = cur0 -sizeof(udp_header_t) - sizeof(ip4_header_t);
          else
            ip6_0 = cur0 -sizeof(udp_header_t) - sizeof(ip6_header_t);

          /* pop (ip, udp, vxlan) */
          vlib_buffer_advance (b0, sizeof(*vxlan0));

          u32 fi0 = buf_fib_index(b0, is_ip4);

          vxlan_tunnel_t * t0, * stats_t0;
          if (is_ip4)
            t0 = vxlan4_find_tunnel (vxm, &last4, fi0, ip4_0, vxlan0, &stats_t0);
          else
            t0 = vxlan6_find_tunnel (vxm, &last6, fi0, ip6_0, vxlan0, &stats_t0);

          uword len0 = vlib_buffer_length_in_chain (vm, b0);

          u32 next0;
          u8 error0 = 0;
          /* Validate VXLAN tunnel encap-fib index agaist packet */
          if (PREDICT_FALSE (t0 == 0 || vxlan0->flags != VXLAN_FLAGS_I))
            {
              next0 = VXLAN_INPUT_NEXT_DROP;

              if (t0 != 0 && vxlan0->flags != VXLAN_FLAGS_I)
                {
                  error0 = VXLAN_ERROR_BAD_FLAGS;
                  vlib_increment_combined_counter
                    (drop_counter, thread_index, stats_t0->sw_if_index, 1, len0);
                }
              else
                error0 = VXLAN_ERROR_NO_SUCH_TUNNEL;
              b0->error = node->errors[error0];
            }
          else
            {
              next0 = t0->decap_next_index;

              /* Required to make the l2 tag push / pop code work on l2 subifs */
              if (PREDICT_TRUE(next0 == VXLAN_INPUT_NEXT_L2_INPUT))
                vnet_update_l2_len (b0);

              /* Set packet input sw_if_index to unicast VXLAN tunnel for learning */
              vnet_buffer(b0)->sw_if_index[VLIB_RX] = t0->sw_if_index;
              pkts_decapsulated++;

              vlib_increment_combined_counter
                (rx_counter, thread_index, stats_t0->sw_if_index, 1, len0);
            }

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
            {
              vxlan_rx_trace_t *tr
                = vlib_add_trace (vm, node, b0, sizeof (*tr));
              tr->next_index = next0;
              tr->error = error0;
              tr->tunnel_index = t0 == 0 ? ~0 : t0 - vxm->tunnels;
              tr->vni = vnet_get_vni (vxlan0);
            }
          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);
    }
  /* Do we still need this now that tunnel tx stats is kept? */
  u32 node_idx = is_ip4 ? vxlan4_input_node.index : vxlan6_input_node.index;
  vlib_node_increment_counter (vm, node_idx, VXLAN_ERROR_DECAPSULATED,
                               pkts_decapsulated);

  return from_frame->n_vectors;
}

static uword
vxlan4_input (vlib_main_t * vm,
             vlib_node_runtime_t * node,
             vlib_frame_t * from_frame)
{
        return vxlan_input(vm, node, from_frame, /* is_ip4 */ 1);
}

static uword
vxlan6_input (vlib_main_t * vm,
             vlib_node_runtime_t * node,
             vlib_frame_t * from_frame)
{
        return vxlan_input(vm, node, from_frame, /* is_ip4 */ 0);
}

static char * vxlan_error_strings[] = {
#define vxlan_error(n,s) s,
#include <vnet/vxlan/vxlan_error.def>
#undef vxlan_error
#undef _
};

VLIB_REGISTER_NODE (vxlan4_input_node) = {
  .function = vxlan4_input,
  .name = "vxlan4-input",
  /* Takes a vector of packets. */
  .vector_size = sizeof (u32),

  .n_errors = VXLAN_N_ERROR,
  .error_strings = vxlan_error_strings,

  .n_next_nodes = VXLAN_INPUT_N_NEXT,
  .next_nodes = {
#define _(s,n) [VXLAN_INPUT_NEXT_##s] = n,
    foreach_vxlan_input_next
#undef _
  },

//temp  .format_buffer = format_vxlan_header,
  .format_trace = format_vxlan_rx_trace,
  // $$$$ .unformat_buffer = unformat_vxlan_header,
};

VLIB_NODE_FUNCTION_MULTIARCH (vxlan4_input_node, vxlan4_input)

VLIB_REGISTER_NODE (vxlan6_input_node) = {
  .function = vxlan6_input,
  .name = "vxlan6-input",
  /* Takes a vector of packets. */
  .vector_size = sizeof (u32),

  .n_errors = VXLAN_N_ERROR,
  .error_strings = vxlan_error_strings,

  .n_next_nodes = VXLAN_INPUT_N_NEXT,
  .next_nodes = {
#define _(s,n) [VXLAN_INPUT_NEXT_##s] = n,
    foreach_vxlan_input_next
#undef _
  },

//temp  .format_buffer = format_vxlan_header,
  .format_trace = format_vxlan_rx_trace,
  // $$$$ .unformat_buffer = unformat_vxlan_header,
};

VLIB_NODE_FUNCTION_MULTIARCH (vxlan6_input_node, vxlan6_input)


typedef enum {
  IP_VXLAN_BYPASS_NEXT_DROP,
  IP_VXLAN_BYPASS_NEXT_VXLAN,
  IP_VXLAN_BYPASS_N_NEXT,
} ip_vxan_bypass_next_t;

always_inline uword
ip_vxlan_bypass_inline (vlib_main_t * vm,
                        vlib_node_runtime_t * node,
                        vlib_frame_t * frame,
                        u32 is_ip4)
{
  vxlan_main_t * vxm = &vxlan_main;
  u32 * from, * to_next, n_left_from, n_left_to_next, next_index;
  vlib_node_runtime_t * error_node = vlib_node_get_runtime (vm, ip4_input_node.index);
  ip4_address_t addr4; /* last IPv4 address matching a local VTEP address */
  ip6_address_t addr6; /* last IPv6 address matching a local VTEP address */

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

  if (node->flags & VLIB_NODE_FLAG_TRACE)
    ip4_forward_next_trace (vm, node, frame, VLIB_TX);

  if (is_ip4) addr4.data_u32 = ~0;
  else ip6_address_set_zero (&addr6);

  while (n_left_from > 0)
    {
      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from >= 4 && n_left_to_next >= 2)
        {
          vlib_buffer_t * b0, * b1;
          ip4_header_t * ip40, * ip41;
          ip6_header_t * ip60, * ip61;
          udp_header_t * udp0, * udp1;
          u32 bi0, ip_len0, udp_len0, flags0, next0;
          u32 bi1, ip_len1, udp_len1, flags1, next1;
          i32 len_diff0, len_diff1;
          u8 error0, good_udp0, proto0;
          u8 error1, good_udp1, proto1;

          /* Prefetch next iteration. */
          {
            vlib_buffer_t * p2, * p3;

            p2 = vlib_get_buffer (vm, from[2]);
            p3 = vlib_get_buffer (vm, from[3]);

            vlib_prefetch_buffer_header (p2, LOAD);
            vlib_prefetch_buffer_header (p3, LOAD);

            CLIB_PREFETCH (p2->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
            CLIB_PREFETCH (p3->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
          }

          bi0 = to_next[0] = from[0];
          bi1 = to_next[1] = from[1];
          from += 2;
          n_left_from -= 2;
          to_next += 2;
          n_left_to_next -= 2;

          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);
          if (is_ip4)
            {
              ip40 = vlib_buffer_get_current (b0);
              ip41 = vlib_buffer_get_current (b1);
            }
          else
            {
              ip60 = vlib_buffer_get_current (b0);
              ip61 = vlib_buffer_get_current (b1);
            }

          /* Setup packet for next IP feature */
          vnet_feature_next(vnet_buffer(b0)->sw_if_index[VLIB_RX], &next0, b0);
          vnet_feature_next(vnet_buffer(b1)->sw_if_index[VLIB_RX], &next1, b1);

          if (is_ip4)
            {
              /* Treat IP frag packets as "experimental" protocol for now
                 until support of IP frag reassembly is implemented */
              proto0 = ip4_is_fragment(ip40) ? 0xfe : ip40->protocol;
              proto1 = ip4_is_fragment(ip41) ? 0xfe : ip41->protocol;
            }
          else
            {
              proto0 = ip60->protocol;
              proto1 = ip61->protocol;
            }

          /* Process packet 0 */
          if (proto0 != IP_PROTOCOL_UDP)
            goto exit0; /* not UDP packet */

          if (is_ip4)
            udp0 = ip4_next_header (ip40);
          else
            udp0 = ip6_next_header (ip60);

          if (udp0->dst_port != clib_host_to_net_u16 (UDP_DST_PORT_vxlan))
            goto exit0; /* not VXLAN packet */

          /* Validate DIP against VTEPs*/
          if (is_ip4)
            {
              if (addr4.as_u32 != ip40->dst_address.as_u32)
                {
                  if (!hash_get (vxm->vtep4, ip40->dst_address.as_u32))
                      goto exit0; /* no local VTEP for VXLAN packet */
                  addr4 = ip40->dst_address;
                }
            }
          else
            {
              if (!ip6_address_is_equal (&addr6, &ip60->dst_address))
                {
                  if (!hash_get_mem (vxm->vtep6, &ip60->dst_address))
                      goto exit0; /* no local VTEP for VXLAN packet */
                  addr6 = ip60->dst_address;
                }
            }

          flags0 = b0->flags;
          good_udp0 = (flags0 & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;

          /* Don't verify UDP checksum for packets with explicit zero checksum. */
          good_udp0 |= udp0->checksum == 0;

          /* Verify UDP length */
          if (is_ip4)
            ip_len0 = clib_net_to_host_u16 (ip40->length);
          else
            ip_len0 = clib_net_to_host_u16 (ip60->payload_length);
          udp_len0 = clib_net_to_host_u16 (udp0->length);
          len_diff0 = ip_len0 - udp_len0;

          /* Verify UDP checksum */
          if (PREDICT_FALSE (!good_udp0))
            {
              if ((flags0 & VNET_BUFFER_F_L4_CHECKSUM_COMPUTED) == 0)
                {
                  if (is_ip4)
                    flags0 = ip4_tcp_udp_validate_checksum (vm, b0);
                  else
                    flags0 = ip6_tcp_udp_icmp_validate_checksum (vm, b0);
                  good_udp0 =
                    (flags0 & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;
                }
            }

          if (is_ip4)
            {
              error0 = good_udp0 ? 0 : IP4_ERROR_UDP_CHECKSUM;
              error0 = (len_diff0 >= 0) ? error0 : IP4_ERROR_UDP_LENGTH;
            }
          else
            {
              error0 = good_udp0 ? 0 : IP6_ERROR_UDP_CHECKSUM;
              error0 = (len_diff0 >= 0) ? error0 : IP6_ERROR_UDP_LENGTH;
            }

          next0 = error0 ?
            IP_VXLAN_BYPASS_NEXT_DROP : IP_VXLAN_BYPASS_NEXT_VXLAN;
          b0->error = error0 ? error_node->errors[error0] : 0;

          /* vxlan-input node expect current at VXLAN header */
          if (is_ip4)
            vlib_buffer_advance (b0, sizeof(ip4_header_t)+sizeof(udp_header_t));
          else
            vlib_buffer_advance (b0, sizeof(ip6_header_t)+sizeof(udp_header_t));

        exit0:
          /* Process packet 1 */
          if (proto1 != IP_PROTOCOL_UDP)
            goto exit1; /* not UDP packet */

          if (is_ip4)
            udp1 = ip4_next_header (ip41);
          else
            udp1 = ip6_next_header (ip61);

          if (udp1->dst_port != clib_host_to_net_u16 (UDP_DST_PORT_vxlan))
            goto exit1; /* not VXLAN packet */

          /* Validate DIP against VTEPs*/
          if (is_ip4)
            {
              if (addr4.as_u32 != ip41->dst_address.as_u32)
                {
                  if (!hash_get (vxm->vtep4, ip41->dst_address.as_u32))
                      goto exit1; /* no local VTEP for VXLAN packet */
                  addr4 = ip41->dst_address;
                }
            }
          else
            {
              if (!ip6_address_is_equal (&addr6, &ip61->dst_address))
                {
                  if (!hash_get_mem (vxm->vtep6, &ip61->dst_address))
                      goto exit1; /* no local VTEP for VXLAN packet */
                  addr6 = ip61->dst_address;
                }
            }

          flags1 = b1->flags;
          good_udp1 = (flags1 & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;

          /* Don't verify UDP checksum for packets with explicit zero checksum. */
          good_udp1 |= udp1->checksum == 0;

          /* Verify UDP length */
          if (is_ip4)
            ip_len1 = clib_net_to_host_u16 (ip41->length);
          else
            ip_len1 = clib_net_to_host_u16 (ip61->payload_length);
          udp_len1 = clib_net_to_host_u16 (udp1->length);
          len_diff1 = ip_len1 - udp_len1;

          /* Verify UDP checksum */
          if (PREDICT_FALSE (!good_udp1))
            {
              if ((flags1 & VNET_BUFFER_F_L4_CHECKSUM_COMPUTED) == 0)
                {
                  if (is_ip4)
                    flags1 = ip4_tcp_udp_validate_checksum (vm, b1);
                  else
                    flags1 = ip6_tcp_udp_icmp_validate_checksum (vm, b1);
                  good_udp1 =
                    (flags1 & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;
                }
            }

          if (is_ip4)
            {
              error1 = good_udp1 ? 0 : IP4_ERROR_UDP_CHECKSUM;
              error1 = (len_diff1 >= 0) ? error1 : IP4_ERROR_UDP_LENGTH;
            }
          else
            {
              error1 = good_udp1 ? 0 : IP6_ERROR_UDP_CHECKSUM;
              error1 = (len_diff1 >= 0) ? error1 : IP6_ERROR_UDP_LENGTH;
            }

          next1 = error1 ?
            IP_VXLAN_BYPASS_NEXT_DROP : IP_VXLAN_BYPASS_NEXT_VXLAN;
          b1->error = error1 ? error_node->errors[error1] : 0;

          /* vxlan-input node expect current at VXLAN header */
          if (is_ip4)
            vlib_buffer_advance (b1, sizeof(ip4_header_t)+sizeof(udp_header_t));
          else
            vlib_buffer_advance (b1, sizeof(ip6_header_t)+sizeof(udp_header_t));

        exit1:
          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, bi1, next0, next1);
        }

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          vlib_buffer_t * b0;
          ip4_header_t * ip40;
          ip6_header_t * ip60;
          udp_header_t * udp0;
          u32 bi0, ip_len0, udp_len0, flags0, next0;
          i32 len_diff0;
          u8 error0, good_udp0, proto0;

          bi0 = to_next[0] = from[0];
          from += 1;
          n_left_from -= 1;
          to_next += 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);
          if (is_ip4)
            ip40 = vlib_buffer_get_current (b0);
          else
            ip60 = vlib_buffer_get_current (b0);

          /* Setup packet for next IP feature */
          vnet_feature_next(vnet_buffer(b0)->sw_if_index[VLIB_RX], &next0, b0);

          if (is_ip4)
            /* Treat IP4 frag packets as "experimental" protocol for now
               until support of IP frag reassembly is implemented */
            proto0 = ip4_is_fragment(ip40) ? 0xfe : ip40->protocol;
          else
            proto0 = ip60->protocol;

          if (proto0 != IP_PROTOCOL_UDP)
            goto exit; /* not UDP packet */

          if (is_ip4)
            udp0 = ip4_next_header (ip40);
          else
            udp0 = ip6_next_header (ip60);

          if (udp0->dst_port != clib_host_to_net_u16 (UDP_DST_PORT_vxlan))
            goto exit; /* not VXLAN packet */

          /* Validate DIP against VTEPs*/
          if (is_ip4)
            {
              if (addr4.as_u32 != ip40->dst_address.as_u32)
                {
                  if (!hash_get (vxm->vtep4, ip40->dst_address.as_u32))
                      goto exit; /* no local VTEP for VXLAN packet */
                  addr4 = ip40->dst_address;
                }
            }
          else
            {
              if (!ip6_address_is_equal (&addr6, &ip60->dst_address))
                {
                  if (!hash_get_mem (vxm->vtep6, &ip60->dst_address))
                      goto exit; /* no local VTEP for VXLAN packet */
                  addr6 = ip60->dst_address;
                }
            }

          flags0 = b0->flags;
          good_udp0 = (flags0 & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;

          /* Don't verify UDP checksum for packets with explicit zero checksum. */
          good_udp0 |= udp0->checksum == 0;

          /* Verify UDP length */
          if (is_ip4)
            ip_len0 = clib_net_to_host_u16 (ip40->length);
          else
            ip_len0 = clib_net_to_host_u16 (ip60->payload_length);
          udp_len0 = clib_net_to_host_u16 (udp0->length);
          len_diff0 = ip_len0 - udp_len0;

          /* Verify UDP checksum */
          if (PREDICT_FALSE (!good_udp0))
            {
              if ((flags0 & VNET_BUFFER_F_L4_CHECKSUM_COMPUTED) == 0)
                {
                  if (is_ip4)
                    flags0 = ip4_tcp_udp_validate_checksum (vm, b0);
                  else
                    flags0 = ip6_tcp_udp_icmp_validate_checksum (vm, b0);
                  good_udp0 =
                    (flags0 & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;
                }
            }

          if (is_ip4)
            {
              error0 = good_udp0 ? 0 : IP4_ERROR_UDP_CHECKSUM;
              error0 = (len_diff0 >= 0) ? error0 : IP4_ERROR_UDP_LENGTH;
            }
          else
            {
              error0 = good_udp0 ? 0 : IP6_ERROR_UDP_CHECKSUM;
              error0 = (len_diff0 >= 0) ? error0 : IP6_ERROR_UDP_LENGTH;
            }

          next0 = error0 ?
            IP_VXLAN_BYPASS_NEXT_DROP : IP_VXLAN_BYPASS_NEXT_VXLAN;
          b0->error = error0 ? error_node->errors[error0] : 0;

          /* vxlan-input node expect current at VXLAN header */
          if (is_ip4)
            vlib_buffer_advance (b0, sizeof(ip4_header_t)+sizeof(udp_header_t));
          else
            vlib_buffer_advance (b0, sizeof(ip6_header_t)+sizeof(udp_header_t));

        exit:
          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;
}

static uword
ip4_vxlan_bypass (vlib_main_t * vm,
                  vlib_node_runtime_t * node,
                  vlib_frame_t * frame)
{
  return ip_vxlan_bypass_inline (vm, node, frame, /* is_ip4 */ 1);
}

VLIB_REGISTER_NODE (ip4_vxlan_bypass_node) = {
  .function = ip4_vxlan_bypass,
  .name = "ip4-vxlan-bypass",
  .vector_size = sizeof (u32),

  .n_next_nodes = IP_VXLAN_BYPASS_N_NEXT,
  .next_nodes = {
    [IP_VXLAN_BYPASS_NEXT_DROP] = "error-drop",
    [IP_VXLAN_BYPASS_NEXT_VXLAN] = "vxlan4-input",
  },

  .format_buffer = format_ip4_header,
  .format_trace = format_ip4_forward_next_trace,
};

VLIB_NODE_FUNCTION_MULTIARCH (ip4_vxlan_bypass_node,ip4_vxlan_bypass)

/* Dummy init function to get us linked in. */
clib_error_t * ip4_vxlan_bypass_init (vlib_main_t * vm)
{ return 0; }

VLIB_INIT_FUNCTION (ip4_vxlan_bypass_init);

static uword
ip6_vxlan_bypass (vlib_main_t * vm,
                  vlib_node_runtime_t * node,
                  vlib_frame_t * frame)
{
  return ip_vxlan_bypass_inline (vm, node, frame, /* is_ip4 */ 0);
}

VLIB_REGISTER_NODE (ip6_vxlan_bypass_node) = {
  .function = ip6_vxlan_bypass,
  .name = "ip6-vxlan-bypass",
  .vector_size = sizeof (u32),

  .n_next_nodes = IP_VXLAN_BYPASS_N_NEXT,
  .next_nodes = {
    [IP_VXLAN_BYPASS_NEXT_DROP] = "error-drop",
    [IP_VXLAN_BYPASS_NEXT_VXLAN] = "vxlan6-input",
  },

  .format_buffer = format_ip6_header,
  .format_trace = format_ip6_forward_next_trace,
};

VLIB_NODE_FUNCTION_MULTIARCH (ip6_vxlan_bypass_node,ip6_vxlan_bypass)

/* Dummy init function to get us linked in. */
clib_error_t * ip6_vxlan_bypass_init (vlib_main_t * vm)
{ return 0; }

VLIB_INIT_FUNCTION (ip6_vxlan_bypass_init);

#define foreach_vxlan_flow_input_next        \
_(DROP, "error-drop")                           \
_(L2_INPUT, "l2-input")

typedef enum
{
#define _(s,n) VXLAN_FLOW_NEXT_##s,
  foreach_vxlan_flow_input_next
#undef _
  VXLAN_FLOW_N_NEXT,
} vxlan_flow_input_next_t;

#define foreach_vxlan_flow_error                                        \
  _(NONE, "no error")                                                   \
  _(IP_CHECKSUM_ERROR, "Rx ip checksum errors")                         \
  _(IP_HEADER_ERROR, "Rx ip header errors")                             \
  _(UDP_CHECKSUM_ERROR, "Rx udp checksum errors")                               \
  _(UDP_LENGTH_ERROR, "Rx udp length errors")

typedef enum
{
#define _(f,s) VXLAN_FLOW_ERROR_##f,
  foreach_vxlan_flow_error
#undef _
    VXLAN_FLOW_N_ERROR,
} vxlan_flow_error_t;

static char *vxlan_flow_error_strings[] = {
#define _(n,s) s,
  foreach_vxlan_flow_error
#undef _
};


static_always_inline u8
vxlan_validate_udp_csum (vlib_main_t * vm, vlib_buffer_t *b)
{
  u32 flags = b->flags;
  enum { offset = sizeof(ip4_header_t) + sizeof(udp_header_t) + sizeof(vxlan_header_t), };

  /* Verify UDP checksum */
  if ((flags & VNET_BUFFER_F_L4_CHECKSUM_COMPUTED) == 0)
  {
    vlib_buffer_advance (b, -offset);
    flags = ip4_tcp_udp_validate_checksum (vm, b);
    vlib_buffer_advance (b, offset);
  }

  return (flags & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;
}

static_always_inline u8
vxlan_check_udp_csum (vlib_main_t * vm, vlib_buffer_t *b)
{
  ip4_vxlan_header_t * hdr = vlib_buffer_get_current(b) - sizeof *hdr;
  udp_header_t * udp = &hdr->udp;
  /* Don't verify UDP checksum for packets with explicit zero checksum. */
  u8 good_csum = (b->flags & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0 ||
    udp->checksum == 0;

  return !good_csum;
}

static_always_inline u8
vxlan_check_ip (vlib_buffer_t *b, u16 payload_len)
{
  ip4_vxlan_header_t * hdr = vlib_buffer_get_current(b) - sizeof *hdr;
  u16 ip_len = clib_net_to_host_u16 (hdr->ip4.length);
  u16 expected = payload_len + sizeof *hdr;
  return ip_len > expected || hdr->ip4.ttl == 0 || hdr->ip4.ip_version_and_header_length != 0x45;
}

static_always_inline u8
vxlan_check_ip_udp_len (vlib_buffer_t *b)
{
  ip4_vxlan_header_t * hdr = vlib_buffer_get_current(b) - sizeof *hdr;
  u16 ip_len = clib_net_to_host_u16 (hdr->ip4.length);
  u16 udp_len = clib_net_to_host_u16 (hdr->udp.length);
  return udp_len > ip_len;
}

static_always_inline u8
vxlan_err_code (u8 ip_err0, u8 udp_err0, u8 csum_err0)
{
  u8 error0 = VXLAN_FLOW_ERROR_NONE;
  if (ip_err0)
    error0 =  VXLAN_FLOW_ERROR_IP_HEADER_ERROR;
  if (udp_err0)
    error0 =  VXLAN_FLOW_ERROR_UDP_LENGTH_ERROR;
  if (csum_err0)
    error0 =  VXLAN_FLOW_ERROR_UDP_CHECKSUM_ERROR;
  return error0;
}

VLIB_NODE_FN (vxlan4_flow_input_node) (vlib_main_t * vm,
                                              vlib_node_runtime_t * node,
                                              vlib_frame_t * f)
{
  enum { payload_offset = sizeof(ip4_vxlan_header_t) };

  vxlan_main_t * vxm = &vxlan_main;
  vnet_interface_main_t * im = &vnet_main.interface_main;
  vlib_combined_counter_main_t * rx_counter[VXLAN_FLOW_N_NEXT] = {
    [VXLAN_FLOW_NEXT_DROP] = im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_DROP,
    [VXLAN_FLOW_NEXT_L2_INPUT] = im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_RX,
  };
  u32 thread_index = vlib_get_thread_index();

  u32 * from = vlib_frame_vector_args (f);
  u32 n_left_from = f->n_vectors;
  u32 next_index = VXLAN_FLOW_NEXT_L2_INPUT;

  while (n_left_from > 0)
  {
    u32 n_left_to_next, *to_next;

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

    while (n_left_from > 3 && n_left_to_next > 3)
    {
      u32 bi0 = to_next[0] = from[0];
      u32 bi1 = to_next[1] = from[1];
      u32 bi2 = to_next[2] = from[2];
      u32 bi3 = to_next[3] = from[3];
      from+=4;
      n_left_from-=4;
      to_next+=4;
      n_left_to_next-=4;

      vlib_buffer_t * b0 = vlib_get_buffer (vm, bi0);
      vlib_buffer_t * b1 = vlib_get_buffer (vm, bi1);
      vlib_buffer_t * b2 = vlib_get_buffer (vm, bi2);
      vlib_buffer_t * b3 = vlib_get_buffer (vm, bi3);

      vlib_buffer_advance (b0, payload_offset);
      vlib_buffer_advance (b1, payload_offset);
      vlib_buffer_advance (b2, payload_offset);
      vlib_buffer_advance (b3, payload_offset);

      u16 len0 = vlib_buffer_length_in_chain (vm, b0);
      u16 len1 = vlib_buffer_length_in_chain (vm, b1);
      u16 len2 = vlib_buffer_length_in_chain (vm, b2);
      u16 len3 = vlib_buffer_length_in_chain (vm, b3);

      u32 next0 = VXLAN_FLOW_NEXT_L2_INPUT, next1 = VXLAN_FLOW_NEXT_L2_INPUT,
          next2 = VXLAN_FLOW_NEXT_L2_INPUT, next3 = VXLAN_FLOW_NEXT_L2_INPUT;

      u8 ip_err0 = vxlan_check_ip (b0, len0);
      u8 ip_err1 = vxlan_check_ip (b1, len1);
      u8 ip_err2 = vxlan_check_ip (b2, len2);
      u8 ip_err3 = vxlan_check_ip (b3, len3);
      u8 ip_err = ip_err0 | ip_err1 | ip_err2 | ip_err3;

      u8 udp_err0 = vxlan_check_ip_udp_len (b0);
      u8 udp_err1 = vxlan_check_ip_udp_len (b1);
      u8 udp_err2 = vxlan_check_ip_udp_len (b2);
      u8 udp_err3 = vxlan_check_ip_udp_len (b3);
      u8 udp_err = udp_err0 | udp_err1 | udp_err2 | udp_err3;

      u8 csum_err0 = vxlan_check_udp_csum (vm, b0);
      u8 csum_err1 = vxlan_check_udp_csum (vm, b1);
      u8 csum_err2 = vxlan_check_udp_csum (vm, b2);
      u8 csum_err3 = vxlan_check_udp_csum (vm, b3);
      u8 csum_err = csum_err0 | csum_err1 | csum_err2 | csum_err3;

      if (PREDICT_FALSE(csum_err))
        {
          if (csum_err0)
            csum_err0 = !vxlan_validate_udp_csum (vm, b0);
          if (csum_err1)
            csum_err1 = !vxlan_validate_udp_csum (vm, b1);
          if (csum_err2)
            csum_err2 = !vxlan_validate_udp_csum (vm, b2);
          if (csum_err3)
            csum_err3 = !vxlan_validate_udp_csum (vm, b3);
          csum_err = csum_err0 | csum_err1 | csum_err2 | csum_err3;
        }

      if (PREDICT_FALSE(ip_err || udp_err || csum_err))
      {
        if (ip_err0 || udp_err0 || csum_err0)
        {
          next0 = VXLAN_FLOW_NEXT_DROP;
          u8 error0 = vxlan_err_code (ip_err0, udp_err0, csum_err0);
          b0->error = node->errors[error0];
        }
        if (ip_err1 || udp_err1 || csum_err1)
        {
          next1 = VXLAN_FLOW_NEXT_DROP;
          u8 error1 = vxlan_err_code (ip_err1, udp_err1, csum_err1);
          b1->error = node->errors[error1];
        }
        if (ip_err2 || udp_err2 || csum_err2)
        {
          next2 = VXLAN_FLOW_NEXT_DROP;
          u8 error2 = vxlan_err_code (ip_err2, udp_err2, csum_err2);
          b2->error = node->errors[error2];
        }
        if (ip_err3 || udp_err3 || csum_err3)
        {
          next3 = VXLAN_FLOW_NEXT_DROP;
          u8 error3 = vxlan_err_code (ip_err3, udp_err3, csum_err3);
          b3->error = node->errors[error3];
        }
      }

      vnet_update_l2_len (b0);
      vnet_update_l2_len (b1);
      vnet_update_l2_len (b2);
      vnet_update_l2_len (b3);

      ASSERT (b0->flow_id != 0);
      ASSERT (b1->flow_id != 0);
      ASSERT (b2->flow_id != 0);
      ASSERT (b3->flow_id != 0);

      u32 t_index0 = b0->flow_id - vxm->flow_id_start;
      u32 t_index1 = b1->flow_id - vxm->flow_id_start;
      u32 t_index2 = b2->flow_id - vxm->flow_id_start;
      u32 t_index3 = b3->flow_id - vxm->flow_id_start;

      vxlan_tunnel_t * t0 = &vxm->tunnels[t_index0];
      vxlan_tunnel_t * t1 = &vxm->tunnels[t_index1];
      vxlan_tunnel_t * t2 = &vxm->tunnels[t_index2];
      vxlan_tunnel_t * t3 = &vxm->tunnels[t_index3];

      /* flow id consumed */
      b0->flow_id = 0;
      b1->flow_id = 0;
      b2->flow_id = 0;
      b3->flow_id = 0;

      u32 sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX] = t0->sw_if_index;
      u32 sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX] = t1->sw_if_index;
      u32 sw_if_index2 = vnet_buffer (b2)->sw_if_index[VLIB_RX] = t2->sw_if_index;
      u32 sw_if_index3 = vnet_buffer (b3)->sw_if_index[VLIB_RX] = t3->sw_if_index;

      vlib_increment_combined_counter (rx_counter[next0], thread_index, sw_if_index0, 1, len0);
      vlib_increment_combined_counter (rx_counter[next1], thread_index, sw_if_index1, 1, len1);
      vlib_increment_combined_counter (rx_counter[next2], thread_index, sw_if_index2, 1, len2);
      vlib_increment_combined_counter (rx_counter[next3], thread_index, sw_if_index3, 1, len3);

      u32 flags = b0->flags | b1->flags | b2->flags | b3->flags;

      if (PREDICT_FALSE(flags & VLIB_BUFFER_IS_TRACED))
        {
          if (b0->flags & VLIB_BUFFER_IS_TRACED)
            {
              vxlan_rx_trace_t *tr = vlib_add_trace (vm, node, b0, sizeof *tr);
              u8 error0 = vxlan_err_code (ip_err0, udp_err0, csum_err0);
              *tr = (vxlan_rx_trace_t) {
                .next_index = next0, .error = error0, .tunnel_index = t_index0, .vni = t0->vni };
            }
          if (b1->flags & VLIB_BUFFER_IS_TRACED)
            {
              vxlan_rx_trace_t *tr = vlib_add_trace (vm, node, b1, sizeof *tr);
              u8 error1 = vxlan_err_code (ip_err1, udp_err1, csum_err1);
              *tr = (vxlan_rx_trace_t) {
                .next_index = next1, .error = error1, .tunnel_index = t_index1, .vni = t1->vni };
            }
          if (b2->flags & VLIB_BUFFER_IS_TRACED)
            {
              vxlan_rx_trace_t *tr = vlib_add_trace (vm, node, b2, sizeof *tr);
              u8 error2 = vxlan_err_code (ip_err2, udp_err2, csum_err2);
              *tr = (vxlan_rx_trace_t) {
                .next_index = next2, .error = error2, .tunnel_index = t_index2, .vni = t2->vni };
            }
          if (b3->flags & VLIB_BUFFER_IS_TRACED)
            {
              vxlan_rx_trace_t *tr = vlib_add_trace (vm, node, b3, sizeof *tr);
              u8 error3 = vxlan_err_code (ip_err3, udp_err3, csum_err3);
              *tr = (vxlan_rx_trace_t) {
                .next_index = next3, .error = error3, .tunnel_index = t_index3, .vni = t3->vni };
            }
        }
      vlib_validate_buffer_enqueue_x4
        (vm, node, next_index, to_next, n_left_to_next,
          bi0, bi1, bi2, bi3, next0, next1, next2, next3);
    }
    while (n_left_from > 0 && n_left_to_next > 0)
    {
      u32 bi0 = to_next[0] = from[0];
      from++;
      n_left_from--;
      to_next++;
      n_left_to_next--;

      vlib_buffer_t * b0 = vlib_get_buffer (vm, bi0);
      vlib_buffer_advance (b0, payload_offset);

      u16 len0 = vlib_buffer_length_in_chain (vm, b0);
      u32 next0 = VXLAN_FLOW_NEXT_L2_INPUT;

      u8 ip_err0 = vxlan_check_ip (b0, len0);
      u8 udp_err0 = vxlan_check_ip_udp_len (b0);
      u8 csum_err0 = vxlan_check_udp_csum (vm, b0);

      if (csum_err0)
        csum_err0 = !vxlan_validate_udp_csum (vm, b0);
      if (ip_err0 || udp_err0 || csum_err0)
      {
        next0 = VXLAN_FLOW_NEXT_DROP;
        u8 error0 = vxlan_err_code (ip_err0, udp_err0, csum_err0);
        b0->error = node->errors[error0];
      }

      vnet_update_l2_len (b0);

      ASSERT (b0->flow_id != 0);
      u32 t_index0 = b0->flow_id - vxm->flow_id_start;
      vxlan_tunnel_t * t0 = &vxm->tunnels[t_index0];
      b0->flow_id = 0;

      u32 sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX] = t0->sw_if_index;
      vlib_increment_combined_counter (rx_counter[next0], thread_index, sw_if_index0, 1, len0);

      if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED)) 
        {
          vxlan_rx_trace_t *tr = vlib_add_trace (vm, node, b0, sizeof *tr);
          u8 error0 = vxlan_err_code (ip_err0, udp_err0, csum_err0);
          *tr = (vxlan_rx_trace_t) {
            .next_index = next0, .error = error0, .tunnel_index = t_index0, .vni = t0->vni };
        }
      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 f->n_vectors;
}

/* *INDENT-OFF* */
#ifndef CLIB_MULTIARCH_VARIANT
VLIB_REGISTER_NODE (vxlan4_flow_input_node) = {
  .name = "vxlan-flow-input",
  .type = VLIB_NODE_TYPE_INTERNAL,
  .vector_size = sizeof (u32),

  .format_trace = format_vxlan_rx_trace,

  .n_errors = VXLAN_FLOW_N_ERROR,
  .error_strings = vxlan_flow_error_strings,

  .n_next_nodes = VXLAN_FLOW_N_NEXT,
  .next_nodes = {
#define _(s,n) [VXLAN_FLOW_NEXT_##s] = n,
    foreach_vxlan_flow_input_next
#undef _
  },
};
#endif
/* *INDENT-ON* */