ip: Protocol Independent IP Neighbors

Type: feature

 - ip-neighbour: generic neighbour handling; APIs, DBs, event handling,
aging
 - arp: ARP protocol implementation
 - ip6-nd; IPv6 neighbor discovery implementation; separate ND,
MLD, RA
 - ip6-link; manage link-local addresses
 - l2-arp-term; events separated from IP neighbours, since they are not
the same.

vnet retains just enough education to perform ND/ARP packet
construction.
arp and ip6-nd to be moved to plugins soon.

Change-Id: I88dedd0006b299344f4c7024a0aa5baa6b9a8bbe
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 934 insertions, 0 deletions

diff --git a/src/vnet/arp/arp.c b/src/vnet/arp/arp.c
new file mode 100644
index 00000000000..14a1ae97d1e
--- /dev/null
+++ b/src/vnet/arp/arp.c
@@ -0,0 +1,934 @@
+/*
+ * ethernet/arp.c: IP v4 ARP node
+ *
+ * Copyright (c) 2010 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 <vnet/arp/arp.h>
+#include <vnet/arp/arp_packet.h>
+
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/fib/fib_entry_src.h>
+#include <vnet/adj/adj_nbr.h>
+#include <vnet/adj/adj_mcast.h>
+
+#include <vnet/ip-neighbor/ip_neighbor.h>
+#include <vnet/ip-neighbor/ip_neighbor_dp.h>
+
+#include <vlibmemory/api.h>
+
+/**
+ * @file
+ * @brief IPv4 ARP.
+ *
+ * This file contains code to manage the IPv4 ARP tables (IP Address
+ * to MAC Address lookup).
+ */
+
+/**
+ * @brief Per-interface ARP configuration and state
+ */
+typedef struct ethernet_arp_interface_t_
+{
+  /**
+   * Is ARP enabled on this interface
+   */
+  u32 enabled;
+} ethernet_arp_interface_t;
+
+typedef struct
+{
+  /* Hash tables mapping name to opcode. */
+  uword *opcode_by_name;
+
+  /** Per interface state */
+  ethernet_arp_interface_t *ethernet_arp_by_sw_if_index;
+
+  /* ARP feature arc index */
+  u8 feature_arc_index;
+} ethernet_arp_main_t;
+
+static ethernet_arp_main_t ethernet_arp_main;
+
+static const u8 vrrp_prefix[] = { 0x00, 0x00, 0x5E, 0x00, 0x01 };
+
+static uword
+unformat_ethernet_arp_opcode_host_byte_order (unformat_input_t * input,
+					      va_list * args)
+{
+  int *result = va_arg (*args, int *);
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  int x, i;
+
+  /* Numeric opcode. */
+  if (unformat (input, "0x%x", &x) || unformat (input, "%d", &x))
+    {
+      if (x >= (1 << 16))
+	return 0;
+      *result = x;
+      return 1;
+    }
+
+  /* Named type. */
+  if (unformat_user (input, unformat_vlib_number_by_name,
+		     am->opcode_by_name, &i))
+    {
+      *result = i;
+      return 1;
+    }
+
+  return 0;
+}
+
+static uword
+unformat_ethernet_arp_opcode_net_byte_order (unformat_input_t * input,
+					     va_list * args)
+{
+  int *result = va_arg (*args, int *);
+  if (!unformat_user
+      (input, unformat_ethernet_arp_opcode_host_byte_order, result))
+    return 0;
+
+  *result = clib_host_to_net_u16 ((u16) * result);
+  return 1;
+}
+
+typedef struct
+{
+  u8 packet_data[64];
+} ethernet_arp_input_trace_t;
+
+static u8 *
+format_ethernet_arp_input_trace (u8 * s, va_list * va)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*va, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*va, vlib_node_t *);
+  ethernet_arp_input_trace_t *t = va_arg (*va, ethernet_arp_input_trace_t *);
+
+  s = format (s, "%U",
+	      format_ethernet_arp_header,
+	      t->packet_data, sizeof (t->packet_data));
+
+  return s;
+}
+
+static int
+arp_is_enabled (ethernet_arp_main_t * am, u32 sw_if_index)
+{
+  if (vec_len (am->ethernet_arp_by_sw_if_index) <= sw_if_index)
+    return 0;
+
+  return (am->ethernet_arp_by_sw_if_index[sw_if_index].enabled);
+}
+
+static void
+arp_enable (ethernet_arp_main_t * am, u32 sw_if_index)
+{
+  if (arp_is_enabled (am, sw_if_index))
+    return;
+
+  vec_validate (am->ethernet_arp_by_sw_if_index, sw_if_index);
+
+  am->ethernet_arp_by_sw_if_index[sw_if_index].enabled = 1;
+
+  vnet_feature_enable_disable ("arp", "arp-reply", sw_if_index, 1, NULL, 0);
+  vnet_feature_enable_disable ("arp", "arp-disabled", sw_if_index, 0, NULL,
+			       0);
+}
+
+static void
+arp_disable (ethernet_arp_main_t * am, u32 sw_if_index)
+{
+  if (!arp_is_enabled (am, sw_if_index))
+    return;
+
+  vnet_feature_enable_disable ("arp", "arp-disabled", sw_if_index, 1, NULL,
+			       0);
+  vnet_feature_enable_disable ("arp", "arp-reply", sw_if_index, 0, NULL, 0);
+
+  am->ethernet_arp_by_sw_if_index[sw_if_index].enabled = 0;
+}
+
+static int
+arp_unnumbered (vlib_buffer_t * p0,
+		u32 input_sw_if_index, u32 conn_sw_if_index)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  vnet_interface_main_t *vim = &vnm->interface_main;
+  vnet_sw_interface_t *si;
+
+  /* verify that the input interface is unnumbered to the connected.
+   * the connected interface is the interface on which the subnet is
+   * configured */
+  si = &vim->sw_interfaces[input_sw_if_index];
+
+  if (!(si->flags & VNET_SW_INTERFACE_FLAG_UNNUMBERED &&
+	(si->unnumbered_sw_if_index == conn_sw_if_index)))
+    {
+      /* the input interface is not unnumbered to the interface on which
+       * the sub-net is configured that covers the ARP request.
+       * So this is not the case for unnumbered.. */
+      return 0;
+    }
+
+  return !0;
+}
+
+always_inline u32
+arp_learn (u32 sw_if_index,
+	   const ethernet_arp_ip4_over_ethernet_address_t * addr)
+{
+  ip_neighbor_learn_t l = {
+    .ip.ip4 = addr->ip4,
+    .type = IP46_TYPE_IP4,
+    .mac = addr->mac,
+    .sw_if_index = sw_if_index,
+  };
+
+  ip_neighbor_learn_dp (&l);
+
+  return (ETHERNET_ARP_ERROR_l3_src_address_learned);
+}
+
+typedef enum arp_input_next_t_
+{
+  ARP_INPUT_NEXT_DROP,
+  ARP_INPUT_NEXT_DISABLED,
+  ARP_INPUT_N_NEXT,
+} arp_input_next_t;
+
+static uword
+arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  u32 n_left_from, next_index, *from, *to_next, n_left_to_next;
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  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)
+    vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
+				   /* stride */ 1,
+				   sizeof (ethernet_arp_input_trace_t));
+
+  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_arp_header_t *arp0;
+	  arp_input_next_t next0;
+	  vlib_buffer_t *p0;
+	  u32 pi0, error0;
+
+	  pi0 = to_next[0] = from[0];
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  arp0 = vlib_buffer_get_current (p0);
+
+	  error0 = ETHERNET_ARP_ERROR_replies_sent;
+	  next0 = ARP_INPUT_NEXT_DROP;
+
+	  error0 =
+	    (arp0->l2_type !=
+	     clib_net_to_host_u16 (ETHERNET_ARP_HARDWARE_TYPE_ethernet) ?
+	     ETHERNET_ARP_ERROR_l2_type_not_ethernet : error0);
+	  error0 =
+	    (arp0->l3_type !=
+	     clib_net_to_host_u16 (ETHERNET_TYPE_IP4) ?
+	     ETHERNET_ARP_ERROR_l3_type_not_ip4 : error0);
+	  error0 =
+	    (0 == arp0->ip4_over_ethernet[0].ip4.as_u32 ?
+	     ETHERNET_ARP_ERROR_l3_dst_address_unset : error0);
+
+	  if (ETHERNET_ARP_ERROR_replies_sent == error0)
+	    {
+	      next0 = ARP_INPUT_NEXT_DISABLED;
+	      vnet_feature_arc_start (am->feature_arc_index,
+				      vnet_buffer (p0)->sw_if_index[VLIB_RX],
+				      &next0, p0);
+	    }
+	  else
+	    p0->error = node->errors[error0];
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, pi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  return frame->n_vectors;
+}
+
+typedef enum arp_disabled_next_t_
+{
+  ARP_DISABLED_NEXT_DROP,
+  ARP_DISABLED_N_NEXT,
+} arp_disabled_next_t;
+
+#define foreach_arp_disabled_error					\
+  _ (DISABLED, "ARP Disabled on this interface")                    \
+
+typedef enum
+{
+#define _(sym,string) ARP_DISABLED_ERROR_##sym,
+  foreach_arp_disabled_error
+#undef _
+    ARP_DISABLED_N_ERROR,
+} arp_disabled_error_t;
+
+static char *arp_disabled_error_strings[] = {
+#define _(sym,string) string,
+  foreach_arp_disabled_error
+#undef _
+};
+
+static uword
+arp_disabled (vlib_main_t * vm,
+	      vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  u32 n_left_from, next_index, *from, *to_next, n_left_to_next;
+
+  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)
+    vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
+				   /* stride */ 1,
+				   sizeof (ethernet_arp_input_trace_t));
+
+  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)
+	{
+	  arp_disabled_next_t next0 = ARP_DISABLED_NEXT_DROP;
+	  vlib_buffer_t *p0;
+	  u32 pi0, error0;
+
+	  next0 = ARP_DISABLED_NEXT_DROP;
+	  error0 = ARP_DISABLED_ERROR_DISABLED;
+
+	  pi0 = to_next[0] = from[0];
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  p0->error = node->errors[error0];
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, pi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  return frame->n_vectors;
+}
+
+enum arp_dst_fib_type
+{
+  ARP_DST_FIB_NONE,
+  ARP_DST_FIB_ADJ,
+  ARP_DST_FIB_CONN
+};
+
+/*
+ * we're looking for FIB sources that indicate the destination
+ * is attached. There may be interposed DPO prior to the one
+ * we are looking for
+ */
+static enum arp_dst_fib_type
+arp_dst_fib_check (const fib_node_index_t fei, fib_entry_flag_t * flags)
+{
+  const fib_entry_t *entry = fib_entry_get (fei);
+  const fib_entry_src_t *entry_src;
+  fib_source_t src;
+  /* *INDENT-OFF* */
+  FOR_EACH_SRC_ADDED(entry, entry_src, src,
+  ({
+    *flags = fib_entry_get_flags_for_source (fei, src);
+    if (fib_entry_is_sourced (fei, FIB_SOURCE_ADJ))
+        return ARP_DST_FIB_ADJ;
+      else if (FIB_ENTRY_FLAG_CONNECTED & *flags)
+        return ARP_DST_FIB_CONN;
+  }))
+  /* *INDENT-ON* */
+
+  return ARP_DST_FIB_NONE;
+}
+
+static uword
+arp_reply (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 n_left_from, next_index, *from, *to_next;
+  u32 n_replies_sent = 0;
+
+  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)
+    vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
+				   /* stride */ 1,
+				   sizeof (ethernet_arp_input_trace_t));
+
+  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)
+	{
+	  vlib_buffer_t *p0;
+	  ethernet_arp_header_t *arp0;
+	  ethernet_header_t *eth_rx;
+	  const ip4_address_t *if_addr0;
+	  u32 pi0, error0, next0, sw_if_index0, conn_sw_if_index0, fib_index0;
+	  u8 dst_is_local0, is_vrrp_reply0;
+	  fib_node_index_t dst_fei, src_fei;
+	  const fib_prefix_t *pfx0;
+	  fib_entry_flag_t src_flags, dst_flags;
+
+	  pi0 = from[0];
+	  to_next[0] = pi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  arp0 = vlib_buffer_get_current (p0);
+	  /* Fill in ethernet header. */
+	  eth_rx = ethernet_buffer_get_header (p0);
+
+	  next0 = ARP_REPLY_NEXT_DROP;
+	  error0 = ETHERNET_ARP_ERROR_replies_sent;
+	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
+
+	  /* Check that IP address is local and matches incoming interface. */
+	  fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
+	  if (~0 == fib_index0)
+	    {
+	      error0 = ETHERNET_ARP_ERROR_interface_no_table;
+	      goto drop;
+
+	    }
+
+	  {
+	    /*
+	     * we're looking for FIB entries that indicate the source
+	     * is attached. There may be more specific non-attached
+	     * routes that match the source, but these do not influence
+	     * whether we respond to an ARP request, i.e. they do not
+	     * influence whether we are the correct way for the sender
+	     * to reach us, they only affect how we reach the sender.
+	     */
+	    fib_entry_t *src_fib_entry;
+	    const fib_prefix_t *pfx;
+	    fib_entry_src_t *src;
+	    fib_source_t source;
+	    int attached;
+	    int mask;
+
+	    mask = 32;
+	    attached = 0;
+
+	    do
+	      {
+		src_fei = ip4_fib_table_lookup (ip4_fib_get (fib_index0),
+						&arp0->
+						ip4_over_ethernet[0].ip4,
+						mask);
+		src_fib_entry = fib_entry_get (src_fei);
+
+		/*
+		 * It's possible that the source that provides the
+		 * flags we need, or the flags we must not have,
+		 * is not the best source, so check then all.
+		 */
+                /* *INDENT-OFF* */
+                FOR_EACH_SRC_ADDED(src_fib_entry, src, source,
+                ({
+                  src_flags = fib_entry_get_flags_for_source (src_fei, source);
+
+                  /* Reject requests/replies with our local interface
+                     address. */
+                  if (FIB_ENTRY_FLAG_LOCAL & src_flags)
+                    {
+                      error0 = ETHERNET_ARP_ERROR_l3_src_address_is_local;
+                      /*
+                       * When VPP has an interface whose address is also
+                       * applied to a TAP interface on the host, then VPP's
+                       * TAP interface will be unnumbered  to the 'real'
+                       * interface and do proxy ARP from the host.
+                       * The curious aspect of this setup is that ARP requests
+                       * from the host will come from the VPP's own address.
+                       * So don't drop immediately here, instead go see if this
+                       * is a proxy ARP case.
+                       */
+                      goto next_feature;
+                    }
+                  /* A Source must also be local to subnet of matching
+                   * interface address. */
+                  if ((FIB_ENTRY_FLAG_ATTACHED & src_flags) ||
+                      (FIB_ENTRY_FLAG_CONNECTED & src_flags))
+                    {
+                      attached = 1;
+                      break;
+                    }
+                  /*
+                   * else
+                   *  The packet was sent from an address that is not
+                   *  connected nor attached i.e. it is not from an
+                   *  address that is covered by a link's sub-net,
+                   *  nor is it a already learned host resp.
+                   */
+                }));
+                /* *INDENT-ON* */
+
+		/*
+		 * shorter mask lookup for the next iteration.
+		 */
+		pfx = fib_entry_get_prefix (src_fei);
+		mask = pfx->fp_len - 1;
+
+		/*
+		 * continue until we hit the default route or we find
+		 * the attached we are looking for. The most likely
+		 * outcome is we find the attached with the first source
+		 * on the first lookup.
+		 */
+	      }
+	    while (!attached &&
+		   !fib_entry_is_sourced (src_fei, FIB_SOURCE_DEFAULT_ROUTE));
+
+	    if (!attached)
+	      {
+		/*
+		 * the matching route is a not attached, i.e. it was
+		 * added as a result of routing, rather than interface/ARP
+		 * configuration. If the matching route is not a host route
+		 * (i.e. a /32)
+		 */
+		error0 = ETHERNET_ARP_ERROR_l3_src_address_not_local;
+		goto drop;
+	      }
+	  }
+
+	  dst_fei = ip4_fib_table_lookup (ip4_fib_get (fib_index0),
+					  &arp0->ip4_over_ethernet[1].ip4,
+					  32);
+	  switch (arp_dst_fib_check (dst_fei, &dst_flags))
+	    {
+	    case ARP_DST_FIB_ADJ:
+	      /*
+	       * We matched an adj-fib on ths source subnet (a /32 previously
+	       * added as a result of ARP). If this request is a gratuitous
+	       * ARP, then learn from it.
+	       * The check for matching an adj-fib, is to prevent hosts
+	       * from spamming us with gratuitous ARPS that might otherwise
+	       * blow our ARP cache
+	       */
+	      if (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+		  arp0->ip4_over_ethernet[1].ip4.as_u32)
+		error0 =
+		  arp_learn (sw_if_index0, &arp0->ip4_over_ethernet[0]);
+	      goto drop;
+	    case ARP_DST_FIB_CONN:
+	      /* destination is connected, continue to process */
+	      break;
+	    case ARP_DST_FIB_NONE:
+	      /* destination is not connected, stop here */
+	      error0 = ETHERNET_ARP_ERROR_l3_dst_address_not_local;
+	      goto next_feature;
+	    }
+
+	  dst_is_local0 = (FIB_ENTRY_FLAG_LOCAL & dst_flags);
+	  pfx0 = fib_entry_get_prefix (dst_fei);
+	  if_addr0 = &pfx0->fp_addr.ip4;
+
+	  is_vrrp_reply0 =
+	    ((arp0->opcode ==
+	      clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply))
+	     &&
+	     (!memcmp
+	      (arp0->ip4_over_ethernet[0].mac.bytes, vrrp_prefix,
+	       sizeof (vrrp_prefix))));
+
+	  /* Trash ARP packets whose ARP-level source addresses do not
+	     match their L2-frame-level source addresses, unless it's
+	     a reply from a VRRP virtual router */
+	  if (!ethernet_mac_address_equal
+	      (eth_rx->src_address,
+	       arp0->ip4_over_ethernet[0].mac.bytes) && !is_vrrp_reply0)
+	    {
+	      error0 = ETHERNET_ARP_ERROR_l2_address_mismatch;
+	      goto drop;
+	    }
+
+	  /* Learn or update sender's mapping only for replies to addresses
+	   * that are local to the subnet */
+	  if (arp0->opcode ==
+	      clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply))
+	    {
+	      if (dst_is_local0)
+		error0 =
+		  arp_learn (sw_if_index0, &arp0->ip4_over_ethernet[0]);
+	      else
+		/* a reply for a non-local destination could be a GARP.
+		 * GARPs for hosts we know were handled above, so this one
+		 * we drop */
+		error0 = ETHERNET_ARP_ERROR_l3_dst_address_not_local;
+
+	      goto next_feature;
+	    }
+	  else if (arp0->opcode ==
+		   clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_request) &&
+		   (dst_is_local0 == 0))
+	    {
+	      goto next_feature;
+	    }
+
+	  /* Honor unnumbered interface, if any */
+	  conn_sw_if_index0 = fib_entry_get_resolving_interface (dst_fei);
+	  if (sw_if_index0 != conn_sw_if_index0 ||
+	      sw_if_index0 != fib_entry_get_resolving_interface (src_fei))
+	    {
+	      /*
+	       * The interface the ARP is sent to or was received on is not the
+	       * interface on which the covering prefix is configured.
+	       * Maybe this is a case for unnumbered.
+	       */
+	      if (!arp_unnumbered (p0, sw_if_index0, conn_sw_if_index0))
+		{
+		  error0 = ETHERNET_ARP_ERROR_unnumbered_mismatch;
+		  goto drop;
+		}
+	    }
+	  if (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+	      arp0->ip4_over_ethernet[1].ip4.as_u32)
+	    {
+	      error0 = ETHERNET_ARP_ERROR_gratuitous_arp;
+	      goto drop;
+	    }
+
+	  next0 = arp_mk_reply (vnm, p0, sw_if_index0,
+				if_addr0, arp0, eth_rx);
+
+	  /* We are going to reply to this request, so, in the absence of
+	     errors, learn the sender */
+	  if (!error0)
+	    error0 = arp_learn (sw_if_index0, &arp0->ip4_over_ethernet[1]);
+
+	  n_replies_sent += 1;
+	  goto enqueue;
+
+	next_feature:
+	  vnet_feature_next (&next0, p0);
+	  goto enqueue;
+
+	drop:
+	  p0->error = node->errors[error0];
+
+	enqueue:
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, pi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_error_count (vm, node->node_index,
+		    ETHERNET_ARP_ERROR_replies_sent, n_replies_sent);
+
+  return frame->n_vectors;
+}
+
+
+static char *ethernet_arp_error_strings[] = {
+#define _(sym,string) string,
+  foreach_ethernet_arp_error
+#undef _
+};
+
+/* *INDENT-OFF* */
+
+VLIB_REGISTER_NODE (arp_input_node, static) =
+{
+  .function = arp_input,
+  .name = "arp-input",
+  .vector_size = sizeof (u32),
+  .n_errors = ETHERNET_ARP_N_ERROR,
+  .error_strings = ethernet_arp_error_strings,
+  .n_next_nodes = ARP_INPUT_N_NEXT,
+  .next_nodes = {
+    [ARP_INPUT_NEXT_DROP] = "error-drop",
+    [ARP_INPUT_NEXT_DISABLED] = "arp-disabled",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_ethernet_arp_input_trace,
+};
+
+VLIB_REGISTER_NODE (arp_disabled_node, static) =
+{
+  .function = arp_disabled,
+  .name = "arp-disabled",
+  .vector_size = sizeof (u32),
+  .n_errors = ARP_DISABLED_N_ERROR,
+  .error_strings = arp_disabled_error_strings,
+  .n_next_nodes = ARP_DISABLED_N_NEXT,
+  .next_nodes = {
+    [ARP_INPUT_NEXT_DROP] = "error-drop",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_ethernet_arp_input_trace,
+};
+
+VLIB_REGISTER_NODE (arp_reply_node, static) =
+{
+  .function = arp_reply,
+  .name = "arp-reply",
+  .vector_size = sizeof (u32),
+  .n_errors = ETHERNET_ARP_N_ERROR,
+  .error_strings = ethernet_arp_error_strings,
+  .n_next_nodes = ARP_REPLY_N_NEXT,
+  .next_nodes = {
+    [ARP_REPLY_NEXT_DROP] = "error-drop",
+    [ARP_REPLY_NEXT_REPLY_TX] = "interface-output",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_ethernet_arp_input_trace,
+};
+
+/* Built-in ARP rx feature path definition */
+VNET_FEATURE_ARC_INIT (arp_feat, static) =
+{
+  .arc_name = "arp",
+  .start_nodes = VNET_FEATURES ("arp-input"),
+  .last_in_arc = "error-drop",
+  .arc_index_ptr = &ethernet_arp_main.feature_arc_index,
+};
+
+VNET_FEATURE_INIT (arp_reply_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "arp-reply",
+  .runs_before = VNET_FEATURES ("arp-disabled"),
+};
+
+VNET_FEATURE_INIT (arp_proxy_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "arp-proxy",
+  .runs_after = VNET_FEATURES ("arp-reply"),
+  .runs_before = VNET_FEATURES ("arp-disabled"),
+};
+
+VNET_FEATURE_INIT (arp_disabled_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "arp-disabled",
+  .runs_before = VNET_FEATURES ("error-drop"),
+};
+
+VNET_FEATURE_INIT (arp_drop_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "error-drop",
+  .runs_before = 0,	/* last feature */
+};
+
+/* *INDENT-ON* */
+
+typedef struct
+{
+  pg_edit_t l2_type, l3_type;
+  pg_edit_t n_l2_address_bytes, n_l3_address_bytes;
+  pg_edit_t opcode;
+  struct
+  {
+    pg_edit_t mac;
+    pg_edit_t ip4;
+  } ip4_over_ethernet[2];
+} pg_ethernet_arp_header_t;
+
+static inline void
+pg_ethernet_arp_header_init (pg_ethernet_arp_header_t * p)
+{
+  /* Initialize fields that are not bit fields in the IP header. */
+#define _(f) pg_edit_init (&p->f, ethernet_arp_header_t, f);
+  _(l2_type);
+  _(l3_type);
+  _(n_l2_address_bytes);
+  _(n_l3_address_bytes);
+  _(opcode);
+  _(ip4_over_ethernet[0].mac);
+  _(ip4_over_ethernet[0].ip4);
+  _(ip4_over_ethernet[1].mac);
+  _(ip4_over_ethernet[1].ip4);
+#undef _
+}
+
+uword
+unformat_pg_arp_header (unformat_input_t * input, va_list * args)
+{
+  pg_stream_t *s = va_arg (*args, pg_stream_t *);
+  pg_ethernet_arp_header_t *p;
+  u32 group_index;
+
+  p = pg_create_edit_group (s, sizeof (p[0]), sizeof (ethernet_arp_header_t),
+			    &group_index);
+  pg_ethernet_arp_header_init (p);
+
+  /* Defaults. */
+  pg_edit_set_fixed (&p->l2_type, ETHERNET_ARP_HARDWARE_TYPE_ethernet);
+  pg_edit_set_fixed (&p->l3_type, ETHERNET_TYPE_IP4);
+  pg_edit_set_fixed (&p->n_l2_address_bytes, 6);
+  pg_edit_set_fixed (&p->n_l3_address_bytes, 4);
+
+  if (!unformat (input, "%U: %U/%U -> %U/%U",
+		 unformat_pg_edit,
+		 unformat_ethernet_arp_opcode_net_byte_order, &p->opcode,
+		 unformat_pg_edit,
+		 unformat_mac_address_t, &p->ip4_over_ethernet[0].mac,
+		 unformat_pg_edit,
+		 unformat_ip4_address, &p->ip4_over_ethernet[0].ip4,
+		 unformat_pg_edit,
+		 unformat_mac_address_t, &p->ip4_over_ethernet[1].mac,
+		 unformat_pg_edit,
+		 unformat_ip4_address, &p->ip4_over_ethernet[1].ip4))
+    {
+      /* Free up any edits we may have added. */
+      pg_free_edit_group (s);
+      return 0;
+    }
+  return 1;
+}
+
+/*
+ * callback when an interface address is added or deleted
+ */
+static void
+arp_enable_disable_interface (ip4_main_t * im,
+			      uword opaque, u32 sw_if_index, u32 is_enable)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  if (is_enable)
+    arp_enable (am, sw_if_index);
+  else
+    arp_disable (am, sw_if_index);
+}
+
+/*
+ * Remove any arp entries associated with the specified interface
+ */
+static clib_error_t *
+vnet_arp_add_del_sw_interface (vnet_main_t * vnm, u32 sw_if_index, u32 is_add)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  if (!is_add && sw_if_index != ~0)
+    {
+      arp_disable (am, sw_if_index);
+    }
+  else if (is_add)
+    {
+      vnet_feature_enable_disable ("arp", "arp-disabled",
+				   sw_if_index, 1, NULL, 0);
+    }
+
+  return (NULL);
+}
+
+VNET_SW_INTERFACE_ADD_DEL_FUNCTION (vnet_arp_add_del_sw_interface);
+
+const static ip_neighbor_vft_t arp_vft = {
+  .inv_proxy4_add = arp_proxy_add,
+  .inv_proxy4_del = arp_proxy_del,
+  .inv_proxy4_enable = arp_proxy_disable,
+  .inv_proxy4_disable = arp_proxy_disable,
+};
+
+static clib_error_t *
+ethernet_arp_init (vlib_main_t * vm)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ip4_main_t *im = &ip4_main;
+  pg_node_t *pn;
+
+  ethernet_register_input_type (vm, ETHERNET_TYPE_ARP, arp_input_node.index);
+
+  pn = pg_get_node (arp_input_node.index);
+  pn->unformat_edit = unformat_pg_arp_header;
+
+  am->opcode_by_name = hash_create_string (0, sizeof (uword));
+#define _(o) hash_set_mem (am->opcode_by_name, #o, ETHERNET_ARP_OPCODE_##o);
+  foreach_ethernet_arp_opcode;
+#undef _
+
+  /* don't trace ARP error packets */
+  {
+    vlib_node_runtime_t *rt =
+      vlib_node_get_runtime (vm, arp_input_node.index);
+
+#define _(a,b)                                  \
+    vnet_pcap_drop_trace_filter_add_del         \
+        (rt->errors[ETHERNET_ARP_ERROR_##a],    \
+         1 /* is_add */);
+    foreach_ethernet_arp_error
+#undef _
+  }
+
+  {
+    ip4_enable_disable_interface_callback_t cb = {
+      .function = arp_enable_disable_interface,
+    };
+    vec_add1 (im->enable_disable_interface_callbacks, cb);
+  }
+
+  ip_neighbor_register (IP46_TYPE_IP4, &arp_vft);
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_INIT_FUNCTION (ethernet_arp_init) =
+{
+  .runs_after = VLIB_INITS("ethernet_init",
+                           "ip_neighbor_init"),
+};
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */