lcp_node.c

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/*
 * lcp_enthernet_node.c : linux control plane ethernet node
 *
 * Copyright (c) 2021 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 <sys/socket.h>
#include <linux/if.h>

#include <plugins/linux-cp/lcp_interface.h>
#include <plugins/linux-cp/lcp_adj.h>
#include <linux-cp/lcp.api_enum.h>

#include <vnet/feature/feature.h>
#include <vnet/ip/ip4_packet.h>
#include <vnet/ethernet/arp_packet.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/ip/ip_types.h>
#include <vnet/ip/lookup.h>
#include <vnet/ip/ip4.h>
#include <vnet/ip/ip6.h>
#include <vnet/l2/l2_input.h>

#define foreach_lip_punt                                                      \
  _ (IO, "punt to host")                                                      \
  _ (DROP, "unknown input interface")

typedef enum
{
#define _(sym, str) LIP_PUNT_NEXT_##sym,
  foreach_lip_punt
#undef _
    LIP_PUNT_N_NEXT,
} lip_punt_next_t;

typedef struct lip_punt_trace_t_
{
  u32 phy_sw_if_index;
  u32 host_sw_if_index;
} lip_punt_trace_t;

/* packet trace format function */
static u8 *
format_lip_punt_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 *);
  lip_punt_trace_t *t = va_arg (*args, lip_punt_trace_t *);

  s =
    format (s, "lip-punt: %u -> %u", t->phy_sw_if_index, t->host_sw_if_index);

  return s;
}

/**
 * Pass punted packets from the PHY to the HOST.
 */
VLIB_NODE_FN (lip_punt_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next, n_left_to_next;
  lip_punt_next_t next_index;

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

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

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          vlib_buffer_t *b0;
          const lcp_itf_pair_t *lip0 = NULL;
          u32 next0 = ~0;
          u32 bi0, lipi0;
          u32 sw_if_index0;
          u8 len0;

          bi0 = to_next[0] = from[0];

          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;
          next0 = LIP_PUNT_NEXT_DROP;

          b0 = vlib_get_buffer (vm, bi0);

          sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
          lipi0 = lcp_itf_pair_find_by_phy (sw_if_index0);
          if (PREDICT_FALSE (lipi0 == INDEX_INVALID))
            goto trace0;

          lip0 = lcp_itf_pair_get (lipi0);
          next0 = LIP_PUNT_NEXT_IO;
          vnet_buffer (b0)->sw_if_index[VLIB_TX] = lip0->lip_host_sw_if_index;

          if (PREDICT_TRUE (lip0->lip_host_type == LCP_ITF_HOST_TAP))
            {
              /*
               * rewind to ethernet header
               */
              len0 = ((u8 *) vlib_buffer_get_current (b0) -
                      (u8 *) ethernet_buffer_get_header (b0));
              vlib_buffer_advance (b0, -len0);
            }
          /* Tun packets don't need any special treatment, just need to
           * be escorted past the TTL decrement. If we still want to use
           * ip[46]-punt-redirect with these, we could just set the
           * VNET_BUFFER_F_LOCALLY_ORIGINATED in an 'else {}' here and
           * then pass to the next node on the ip[46]-punt feature arc
           */

        trace0:
          if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lip_punt_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
              t->phy_sw_if_index = sw_if_index0;
              t->host_sw_if_index =
                (lipi0 == INDEX_INVALID) ? ~0 : lip0->lip_host_sw_if_index;
            }

          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_REGISTER_NODE (lip_punt_node) = {
  .name = "linux-cp-punt",
  .vector_size = sizeof (u32),
  .format_trace = format_lip_punt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_next_nodes = LIP_PUNT_N_NEXT,
  .next_nodes = {
    [LIP_PUNT_NEXT_DROP] = "error-drop",
    [LIP_PUNT_NEXT_IO] = "interface-output",
  },
};

#define foreach_lcp_punt_l3 _ (DROP, "unknown error")

typedef enum
{
#define _(sym, str) LCP_LOCAL_NEXT_##sym,
  foreach_lcp_punt_l3
#undef _
    LCP_LOCAL_N_NEXT,
} lcp_punt_l3_next_t;

typedef struct lcp_punt_l3_trace_t_
{
  u32 phy_sw_if_index;
} lcp_punt_l3_trace_t;

/* packet trace format function */
static u8 *
format_lcp_punt_l3_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 *);
  lcp_punt_l3_trace_t *t = va_arg (*args, lcp_punt_l3_trace_t *);

  s = format (s, "linux-cp-punt-l3: %u", t->phy_sw_if_index);

  return s;
}

VLIB_NODE_FN (lcp_punt_l3_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next, n_left_to_next;
  lip_punt_next_t next_index;

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

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

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          vlib_buffer_t *b0;
          u32 next0 = LCP_LOCAL_NEXT_DROP;
          u32 bi0;
          index_t lipi0;
          lcp_itf_pair_t *lip0;

          bi0 = to_next[0] = from[0];

          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);
          vnet_feature_next (&next0, b0);

          lipi0 =
            lcp_itf_pair_find_by_phy (vnet_buffer (b0)->sw_if_index[VLIB_RX]);
          if (lipi0 != INDEX_INVALID)
            {
              /*
               * Avoid TTL check for packets which arrived on a tunnel and
               * are being punted to the local host.
               */
              lip0 = lcp_itf_pair_get (lipi0);
              if (lip0->lip_host_type == LCP_ITF_HOST_TUN)
                b0->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
            }

          if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lcp_punt_l3_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->phy_sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
            }

          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_REGISTER_NODE (lcp_punt_l3_node) = {
  .name = "linux-cp-punt-l3",
  .vector_size = sizeof (u32),
  .format_trace = format_lcp_punt_l3_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_next_nodes = 1,
  .next_nodes = {
    [LCP_LOCAL_NEXT_DROP] = "error-drop",
  },
};

VNET_FEATURE_INIT (lcp_punt_l3_ip4, static) = {
  .arc_name = "ip4-punt",
  .node_name = "linux-cp-punt-l3",
  .runs_before = VNET_FEATURES ("ip4-punt-redirect"),
};

VNET_FEATURE_INIT (lip_punt_l3_ip6, static) = {
  .arc_name = "ip6-punt",
  .node_name = "linux-cp-punt-l3",
  .runs_before = VNET_FEATURES ("ip6-punt-redirect"),
};

#define foreach_lcp_xc                                                        \
  _ (DROP, "drop")                                                            \
  _ (XC_IP4, "x-connnect-ip4")                                                \
  _ (XC_IP6, "x-connnect-ip6")

typedef enum
{
#define _(sym, str) LCP_XC_NEXT_##sym,
  foreach_lcp_xc
#undef _
    LCP_XC_N_NEXT,
} lcp_xc_next_t;

typedef struct lcp_xc_trace_t_
{
  u32 phy_sw_if_index;
  adj_index_t adj_index;
} lcp_xc_trace_t;

/* packet trace format function */
static u8 *
format_lcp_xc_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 *);
  lcp_xc_trace_t *t = va_arg (*args, lcp_xc_trace_t *);

  s = format (s, "lcp-xc: itf:%d adj:%d", t->phy_sw_if_index, t->adj_index);

  return s;
}

/**
 * X-connect all packets from the HOST to the PHY.
 *
 * This runs in either the IP4 or IP6 path. The MAC rewrite on the received
 * packet from the host is used as a key to find the adjacency used on the phy.
 * This allows this code to start the feature arc on that adjacency.
 * Consequently, all packet sent from the host are also subject to output
 * features, which is symmetric w.r.t. to input features.
 */
static_always_inline u32
lcp_xc_inline (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame,
               ip_address_family_t af)
{
  u32 n_left_from, *from, *to_next, n_left_to_next;
  lcp_xc_next_t next_index;
  ip_lookup_main_t *lm;

  next_index = 0;
  n_left_from = frame->n_vectors;
  from = vlib_frame_vector_args (frame);

  if (AF_IP4 == af)
    lm = &ip4_main.lookup_main;
  else
    lm = &ip6_main.lookup_main;

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

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          const ethernet_header_t *eth;
          const lcp_itf_pair_t *lip;
          u32 next0, bi0, lipi, ai;
          vlib_buffer_t *b0;

          bi0 = to_next[0] = from[0];

          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);

          lipi =
            lcp_itf_pair_find_by_host (vnet_buffer (b0)->sw_if_index[VLIB_RX]);
          lip = lcp_itf_pair_get (lipi);

          vnet_buffer (b0)->sw_if_index[VLIB_TX] = lip->lip_phy_sw_if_index;
          vlib_buffer_advance (b0, -lip->lip_rewrite_len);
          eth = vlib_buffer_get_current (b0);

          if (ethernet_address_cast (eth->dst_address))
            ai = lip->lip_phy_adjs.adj_index[af];
          else
            ai = lcp_adj_lkup ((u8 *) eth, lip->lip_rewrite_len,
                               vnet_buffer (b0)->sw_if_index[VLIB_TX]);

          if (ADJ_INDEX_INVALID != ai)
            {
              const ip_adjacency_t *adj;

              adj = adj_get (ai);
              vnet_buffer (b0)->ip.adj_index[VLIB_TX] = ai;
              next0 = adj->rewrite_header.next_index;
              vnet_buffer (b0)->ip.save_rewrite_length = lip->lip_rewrite_len;

              if (PREDICT_FALSE (adj->rewrite_header.flags &
                                 VNET_REWRITE_HAS_FEATURES))
                vnet_feature_arc_start_w_cfg_index (
                  lm->output_feature_arc_index,
                  vnet_buffer (b0)->sw_if_index[VLIB_TX], &next0, b0,
                  adj->ia_cfg_index);
            }
          else
            next0 = LCP_XC_NEXT_DROP;

          if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lcp_xc_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
              t->phy_sw_if_index = lip->lip_phy_sw_if_index;
              t->adj_index = vnet_buffer (b0)->ip.adj_index[VLIB_TX];
            }

          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 (lcp_xc_ip4)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return (lcp_xc_inline (vm, node, frame, AF_IP4));
}

VLIB_NODE_FN (lcp_xc_ip6)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return (lcp_xc_inline (vm, node, frame, AF_IP6));
}

VLIB_REGISTER_NODE (lcp_xc_ip4) = { .name = "linux-cp-xc-ip4",
                                    .vector_size = sizeof (u32),
                                    .format_trace = format_lcp_xc_trace,
                                    .type = VLIB_NODE_TYPE_INTERNAL,
                                    .sibling_of = "ip4-rewrite" };

VNET_FEATURE_INIT (lcp_xc_ip4_ucast_node, static) = {
  .arc_name = "ip4-unicast",
  .node_name = "linux-cp-xc-ip4",
};
VNET_FEATURE_INIT (lcp_xc_ip4_mcast_node, static) = {
  .arc_name = "ip4-multicast",
  .node_name = "linux-cp-xc-ip4",
};

VLIB_REGISTER_NODE (lcp_xc_ip6) = { .name = "linux-cp-xc-ip6",
                                    .vector_size = sizeof (u32),
                                    .format_trace = format_lcp_xc_trace,
                                    .type = VLIB_NODE_TYPE_INTERNAL,
                                    .sibling_of = "ip6-rewrite" };

VNET_FEATURE_INIT (lcp_xc_ip6_ucast_node, static) = {
  .arc_name = "ip6-unicast",
  .node_name = "linux-cp-xc-ip6",
};
VNET_FEATURE_INIT (lcp_xc_ip6_mcast_node, static) = {
  .arc_name = "ip6-multicast",
  .node_name = "linux-cp-xc-ip6",
};

typedef enum
{
  LCP_XC_L3_NEXT_XC,
  LCP_XC_L3_N_NEXT,
} lcp_xc_l3_next_t;

/**
 * X-connect all packets from the HOST to the PHY on L3 interfaces
 *
 * There's only one adjacency that can be used on thises links.
 */
static_always_inline u32
lcp_xc_l3_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
                  vlib_frame_t *frame, ip_address_family_t af)
{
  u32 n_left_from, *from, *to_next, n_left_to_next;
  lcp_xc_next_t next_index;

  next_index = 0;
  n_left_from = frame->n_vectors;
  from = vlib_frame_vector_args (frame);

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

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          vlib_buffer_t *b0;
          const lcp_itf_pair_t *lip;
          u32 next0 = ~0;
          u32 bi0, lipi;

          bi0 = to_next[0] = from[0];

          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);

          /* Flag buffers as locally originated. Otherwise their TTL will
           * be checked & decremented. That would break services like BGP
           * which set a TTL of 1 by default.
           */
          b0->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;

          lipi =
            lcp_itf_pair_find_by_host (vnet_buffer (b0)->sw_if_index[VLIB_RX]);
          lip = lcp_itf_pair_get (lipi);

          vnet_buffer (b0)->sw_if_index[VLIB_TX] = lip->lip_phy_sw_if_index;
          next0 = LCP_XC_L3_NEXT_XC;
          vnet_buffer (b0)->ip.adj_index[VLIB_TX] =
            lip->lip_phy_adjs.adj_index[af];

          if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lcp_xc_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
              t->phy_sw_if_index = lip->lip_phy_sw_if_index;
              t->adj_index = vnet_buffer (b0)->ip.adj_index[VLIB_TX];
            }

          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;
}

/**
 * X-connect all packets from the HOST to the PHY.
 */
VLIB_NODE_FN (lcp_xc_l3_ip4_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return (lcp_xc_l3_inline (vm, node, frame, AF_IP4));
}

VLIB_NODE_FN (lcp_xc_l3_ip6_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return (lcp_xc_l3_inline (vm, node, frame, AF_IP6));
}

VLIB_REGISTER_NODE (lcp_xc_l3_ip4_node) = {
  .name = "linux-cp-xc-l3-ip4",
  .vector_size = sizeof (u32),
  .format_trace = format_lcp_xc_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_next_nodes = LCP_XC_L3_N_NEXT,
  .next_nodes = {
    [LCP_XC_L3_NEXT_XC] = "ip4-midchain",
  },
};

VNET_FEATURE_INIT (lcp_xc_node_l3_ip4_unicast, static) = {
  .arc_name = "ip4-unicast",
  .node_name = "linux-cp-xc-l3-ip4",
};

VNET_FEATURE_INIT (lcp_xc_node_l3_ip4_multicaast, static) = {
  .arc_name = "ip4-multicast",
  .node_name = "linux-cp-xc-l3-ip4",
};

VLIB_REGISTER_NODE (lcp_xc_l3_ip6_node) = {
  .name = "linux-cp-xc-l3-ip6",
  .vector_size = sizeof (u32),
  .format_trace = format_lcp_xc_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_next_nodes = LCP_XC_L3_N_NEXT,
  .next_nodes = {
    [LCP_XC_L3_NEXT_XC] = "ip6-midchain",
  },
};

VNET_FEATURE_INIT (lcp_xc_node_l3_ip6_unicast, static) = {
  .arc_name = "ip6-unicast",
  .node_name = "linux-cp-xc-l3-ip6",
};

VNET_FEATURE_INIT (lcp_xc_node_l3_ip6_multicast, static) = {
  .arc_name = "ip6-multicast",
  .node_name = "linux-cp-xc-l3-ip6",
};

#define foreach_lcp_arp                                                       \
  _ (DROP, "error-drop")                                                      \
  _ (IO, "interface-output")

typedef enum
{
#define _(sym, str) LCP_ARP_NEXT_##sym,
  foreach_lcp_arp
#undef _
    LCP_ARP_N_NEXT,
} lcp_arp_next_t;

typedef struct lcp_arp_trace_t_
{
  u32 rx_sw_if_index;
  u16 arp_opcode;
} lcp_arp_trace_t;

/* packet trace format function */
static u8 *
format_lcp_arp_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 *);
  lcp_arp_trace_t *t = va_arg (*args, lcp_arp_trace_t *);

  s = format (s, "rx-sw-if-index: %u opcode: %u", t->rx_sw_if_index,
              t->arp_opcode);

  return s;
}

/**
 * punt ARP replies to the host
 */
VLIB_NODE_FN (lcp_arp_phy_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next, n_left_to_next;
  lcp_arp_next_t next_index;
  u32 reply_copies[VLIB_FRAME_SIZE];
  u32 n_copies = 0;

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

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

      while (n_left_from >= 2 && n_left_to_next >= 2)
        {
          u32 next0, next1, bi0, bi1;
          vlib_buffer_t *b0, *b1;
          ethernet_arp_header_t *arp0, *arp1;

          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;

          next0 = next1 = LCP_ARP_NEXT_DROP;

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

          arp0 = vlib_buffer_get_current (b0);
          arp1 = vlib_buffer_get_current (b1);

          vnet_feature_next (&next0, b0);
          vnet_feature_next (&next1, b1);

          /*
           * Replies might need to be received by the host, so we
           * make a copy of them.
           */
          if (arp0->opcode == clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply))
            {
              lcp_itf_pair_t *lip0 = 0;
              u32 lipi0;
              vlib_buffer_t *c0;
              u8 len0;

              lipi0 = lcp_itf_pair_find_by_phy (
                vnet_buffer (b0)->sw_if_index[VLIB_RX]);
              lip0 = lcp_itf_pair_get (lipi0);

              if (lip0)
                {
                  /*
                   * rewind to eth header, copy, advance back to current
                   */
                  len0 = ((u8 *) vlib_buffer_get_current (b0) -
                          (u8 *) ethernet_buffer_get_header (b0));
                  vlib_buffer_advance (b0, -len0);
                  c0 = vlib_buffer_copy (vm, b0);
                  vlib_buffer_advance (b0, len0);

                  /* Send to the host */
                  vnet_buffer (c0)->sw_if_index[VLIB_TX] =
                    lip0->lip_host_sw_if_index;
                  reply_copies[n_copies++] = vlib_get_buffer_index (vm, c0);
                }
            }
          if (arp1->opcode == clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply))
            {
              lcp_itf_pair_t *lip1 = 0;
              u32 lipi1;
              vlib_buffer_t *c1;
              u8 len1;

              lipi1 = lcp_itf_pair_find_by_phy (
                vnet_buffer (b1)->sw_if_index[VLIB_RX]);
              lip1 = lcp_itf_pair_get (lipi1);

              if (lip1)
                {
                  /*
                   * rewind to reveal the ethernet header
                   */
                  len1 = ((u8 *) vlib_buffer_get_current (b1) -
                          (u8 *) ethernet_buffer_get_header (b1));
                  vlib_buffer_advance (b1, -len1);
                  c1 = vlib_buffer_copy (vm, b1);
                  vlib_buffer_advance (b1, len1);

                  /* Send to the host */
                  vnet_buffer (c1)->sw_if_index[VLIB_TX] =
                    lip1->lip_host_sw_if_index;
                  reply_copies[n_copies++] = vlib_get_buffer_index (vm, c1);
                }
            }

          if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lcp_arp_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
              t->rx_sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
            }
          if (PREDICT_FALSE ((b1->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lcp_arp_trace_t *t = vlib_add_trace (vm, node, b1, sizeof (*t));
              t->rx_sw_if_index = vnet_buffer (b1)->sw_if_index[VLIB_RX];
            }

          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 next0, bi0;
          vlib_buffer_t *b0;
          ethernet_arp_header_t *arp0;
          u16 arp_opcode;

          bi0 = to_next[0] = from[0];

          from += 1;
          n_left_from -= 1;
          to_next += 1;
          n_left_to_next -= 1;
          next0 = LCP_ARP_NEXT_DROP;

          b0 = vlib_get_buffer (vm, bi0);
          arp0 = vlib_buffer_get_current (b0);

          vnet_feature_next (&next0, b0);

          /*
           * Replies might need to be received by the host, so we
           * make a copy of them.
           */
          arp_opcode = clib_host_to_net_u16 (arp0->opcode);

          if (arp_opcode == ETHERNET_ARP_OPCODE_reply)
            {
              lcp_itf_pair_t *lip0 = 0;
              vlib_buffer_t *c0;
              u32 lipi0;
              u8 len0;

              lipi0 = lcp_itf_pair_find_by_phy (
                vnet_buffer (b0)->sw_if_index[VLIB_RX]);
              lip0 = lcp_itf_pair_get (lipi0);

              if (lip0)
                {

                  /*
                   * rewind to reveal the ethernet header
                   */
                  len0 = ((u8 *) vlib_buffer_get_current (b0) -
                          (u8 *) ethernet_buffer_get_header (b0));
                  vlib_buffer_advance (b0, -len0);
                  c0 = vlib_buffer_copy (vm, b0);
                  vlib_buffer_advance (b0, len0);

                  /* Send to the host */
                  vnet_buffer (c0)->sw_if_index[VLIB_TX] =
                    lip0->lip_host_sw_if_index;
                  reply_copies[n_copies++] = vlib_get_buffer_index (vm, c0);
                }
            }

          if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lcp_arp_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
              t->rx_sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
              t->arp_opcode = arp_opcode;
            }

          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);
    }

  if (n_copies)
    vlib_buffer_enqueue_to_single_next (vm, node, reply_copies,
                                        LCP_ARP_NEXT_IO, n_copies);

  return frame->n_vectors;
}

VLIB_REGISTER_NODE (lcp_arp_phy_node) = {
  .name = "linux-cp-arp-phy",
  .vector_size = sizeof (u32),
  .format_trace = format_lcp_arp_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = LINUXCP_N_ERROR,
  .error_counters = linuxcp_error_counters,

  .n_next_nodes = LCP_ARP_N_NEXT,
  .next_nodes = {
    [LCP_ARP_NEXT_DROP] = "error-drop",
    [LCP_ARP_NEXT_IO] = "interface-output",
  },
};

VNET_FEATURE_INIT (lcp_arp_phy_arp_feat, static) = {
  .arc_name = "arp",
  .node_name = "linux-cp-arp-phy",
  .runs_before = VNET_FEATURES ("arp-reply"),
};

/**
 * x-connect ARP packets from the host to the phy
 */
VLIB_NODE_FN (lcp_arp_host_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next, n_left_to_next;
  lcp_arp_next_t next_index;

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

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

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          const lcp_itf_pair_t *lip0;
          lcp_arp_next_t next0;
          vlib_buffer_t *b0;
          u32 bi0, lipi0;
          u8 len0;

          bi0 = to_next[0] = from[0];

          from += 1;
          n_left_from -= 1;
          to_next += 1;
          n_left_to_next -= 1;
          next0 = LCP_ARP_NEXT_IO;

          b0 = vlib_get_buffer (vm, bi0);

          lipi0 =
            lcp_itf_pair_find_by_host (vnet_buffer (b0)->sw_if_index[VLIB_RX]);
          lip0 = lcp_itf_pair_get (lipi0);

          /* Send to the phy */
          vnet_buffer (b0)->sw_if_index[VLIB_TX] = lip0->lip_phy_sw_if_index;

          len0 = ((u8 *) vlib_buffer_get_current (b0) -
                  (u8 *) ethernet_buffer_get_header (b0));
          vlib_buffer_advance (b0, -len0);

          if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              lcp_arp_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
              t->rx_sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
            }

          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_REGISTER_NODE (lcp_arp_host_node) = {
  .name = "linux-cp-arp-host",
  .vector_size = sizeof (u32),
  .format_trace = format_lcp_arp_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = LINUXCP_N_ERROR,
  .error_counters = linuxcp_error_counters,

  .n_next_nodes = LCP_ARP_N_NEXT,
  .next_nodes = {
    [LCP_ARP_NEXT_DROP] = "error-drop",
    [LCP_ARP_NEXT_IO] = "interface-output",
  },
};

VNET_FEATURE_INIT (lcp_arp_host_arp_feat, static) = {
  .arc_name = "arp",
  .node_name = "linux-cp-arp-host",
  .runs_before = VNET_FEATURES ("arp-reply"),
};

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