gre: move to a plugin

Move GRE folder under vnet to the plugin folder, and modify some of path
of the #inlude<header> to the new path.

Add a plugin.c file to register a plugin.

JIRA: VPP-2044

Type: improvement
Change-Id: I7f64cecd97538a7492e56a41558dab58281a9fa5
Signed-off-by: Chuhao Tang <nicotang@cisco.com>

1 files changed, 846 insertions, 0 deletions

diff --git a/src/plugins/gre/gre.c b/src/plugins/gre/gre.c
new file mode 100644
index 00000000000..a15717475f8
--- /dev/null
+++ b/src/plugins/gre/gre.c
@@ -0,0 +1,846 @@
+/*
+ * gre.c: gre
+ *
+ * Copyright (c) 2012 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/vnet.h>
+#include <gre/gre.h>
+#include <vnet/adj/adj_midchain.h>
+#include <vnet/tunnel/tunnel_dp.h>
+#include <vpp/app/version.h>
+#include <vnet/plugin/plugin.h>
+
+extern gre_main_t gre_main;
+
+#ifndef CLIB_MARCH_VARIANT
+gre_main_t gre_main;
+
+typedef struct
+{
+  union
+  {
+    ip4_and_gre_header_t ip4_and_gre;
+    u64 as_u64[3];
+  };
+} ip4_and_gre_union_t;
+
+typedef struct
+{
+  union
+  {
+    ip6_and_gre_header_t ip6_and_gre;
+    u64 as_u64[3];
+  };
+} ip6_and_gre_union_t;
+#endif /* CLIB_MARCH_VARIANT */
+
+/* Packet trace structure */
+typedef struct
+{
+  /* Tunnel-id / index in tunnel vector */
+  u32 tunnel_id;
+
+  /* pkt length */
+  u32 length;
+
+  /* tunnel ip addresses */
+  ip46_address_t src;
+  ip46_address_t dst;
+} gre_tx_trace_t;
+
+extern u8 *format_gre_tx_trace (u8 *s, va_list *args);
+
+#ifndef CLIB_MARCH_VARIANT
+u8 *
+format_gre_tx_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 *);
+  gre_tx_trace_t *t = va_arg (*args, gre_tx_trace_t *);
+
+  s = format (s, "GRE: tunnel %d len %d src %U dst %U", t->tunnel_id,
+	      t->length, format_ip46_address, &t->src, IP46_TYPE_ANY,
+	      format_ip46_address, &t->dst, IP46_TYPE_ANY);
+  return s;
+}
+
+u8 *
+format_gre_protocol (u8 *s, va_list *args)
+{
+  gre_protocol_t p = va_arg (*args, u32);
+  gre_main_t *gm = &gre_main;
+  gre_protocol_info_t *pi = gre_get_protocol_info (gm, p);
+
+  if (pi)
+    s = format (s, "%s", pi->name);
+  else
+    s = format (s, "0x%04x", p);
+
+  return s;
+}
+
+u8 *
+format_gre_header_with_length (u8 *s, va_list *args)
+{
+  gre_main_t *gm = &gre_main;
+  gre_header_t *h = va_arg (*args, gre_header_t *);
+  u32 max_header_bytes = va_arg (*args, u32);
+  gre_protocol_t p = clib_net_to_host_u16 (h->protocol);
+  u32 indent, header_bytes;
+
+  header_bytes = sizeof (h[0]);
+  if (max_header_bytes != 0 && header_bytes > max_header_bytes)
+    return format (s, "gre header truncated");
+
+  indent = format_get_indent (s);
+
+  s = format (s, "GRE %U", format_gre_protocol, p);
+
+  if (max_header_bytes != 0 && header_bytes < max_header_bytes)
+    {
+      gre_protocol_info_t *pi = gre_get_protocol_info (gm, p);
+      vlib_node_t *node = vlib_get_node (gm->vlib_main, pi->node_index);
+      if (node->format_buffer)
+	s =
+	  format (s, "\n%U%U", format_white_space, indent, node->format_buffer,
+		  (void *) (h + 1), max_header_bytes - header_bytes);
+    }
+
+  return s;
+}
+
+u8 *
+format_gre_header (u8 *s, va_list *args)
+{
+  gre_header_t *h = va_arg (*args, gre_header_t *);
+  return format (s, "%U", format_gre_header_with_length, h, 0);
+}
+
+/* Returns gre protocol as an int in host byte order. */
+uword
+unformat_gre_protocol_host_byte_order (unformat_input_t *input, va_list *args)
+{
+  u16 *result = va_arg (*args, u16 *);
+  gre_main_t *gm = &gre_main;
+  int i;
+
+  /* Named type. */
+  if (unformat_user (input, unformat_vlib_number_by_name,
+		     gm->protocol_info_by_name, &i))
+    {
+      gre_protocol_info_t *pi = vec_elt_at_index (gm->protocol_infos, i);
+      *result = pi->protocol;
+      return 1;
+    }
+
+  return 0;
+}
+
+uword
+unformat_gre_protocol_net_byte_order (unformat_input_t *input, va_list *args)
+{
+  u16 *result = va_arg (*args, u16 *);
+  if (!unformat_user (input, unformat_gre_protocol_host_byte_order, result))
+    return 0;
+  *result = clib_host_to_net_u16 ((u16) *result);
+  return 1;
+}
+
+uword
+unformat_gre_header (unformat_input_t *input, va_list *args)
+{
+  u8 **result = va_arg (*args, u8 **);
+  gre_header_t _h, *h = &_h;
+  u16 p;
+
+  if (!unformat (input, "%U", unformat_gre_protocol_host_byte_order, &p))
+    return 0;
+
+  h->protocol = clib_host_to_net_u16 (p);
+
+  /* Add header to result. */
+  {
+    void *p;
+    u32 n_bytes = sizeof (h[0]);
+
+    vec_add2 (*result, p, n_bytes);
+    clib_memcpy (p, h, n_bytes);
+  }
+
+  return 1;
+}
+
+static int
+gre_proto_from_vnet_link (vnet_link_t link)
+{
+  switch (link)
+    {
+    case VNET_LINK_IP4:
+      return (GRE_PROTOCOL_ip4);
+    case VNET_LINK_IP6:
+      return (GRE_PROTOCOL_ip6);
+    case VNET_LINK_MPLS:
+      return (GRE_PROTOCOL_mpls_unicast);
+    case VNET_LINK_ETHERNET:
+      return (GRE_PROTOCOL_teb);
+    case VNET_LINK_ARP:
+      return (GRE_PROTOCOL_arp);
+    case VNET_LINK_NSH:
+      ASSERT (0);
+      break;
+    }
+  ASSERT (0);
+  return (GRE_PROTOCOL_ip4);
+}
+
+static u8 *
+gre_build_rewrite (vnet_main_t *vnm, u32 sw_if_index, vnet_link_t link_type,
+		   const void *dst_address)
+{
+  gre_main_t *gm = &gre_main;
+  const ip46_address_t *dst;
+  ip4_and_gre_header_t *h4;
+  ip6_and_gre_header_t *h6;
+  gre_header_t *gre;
+  u8 *rewrite = NULL;
+  gre_tunnel_t *t;
+  u32 ti;
+  u8 is_ipv6;
+
+  dst = dst_address;
+  ti = gm->tunnel_index_by_sw_if_index[sw_if_index];
+
+  if (~0 == ti)
+    /* not one of ours */
+    return (0);
+
+  t = pool_elt_at_index (gm->tunnels, ti);
+
+  is_ipv6 = t->tunnel_dst.fp_proto == FIB_PROTOCOL_IP6 ? 1 : 0;
+
+  if (!is_ipv6)
+    {
+      vec_validate (rewrite, sizeof (*h4) - 1);
+      h4 = (ip4_and_gre_header_t *) rewrite;
+      gre = &h4->gre;
+      h4->ip4.ip_version_and_header_length = 0x45;
+      h4->ip4.ttl = 254;
+      h4->ip4.protocol = IP_PROTOCOL_GRE;
+      /* fixup ip4 header length and checksum after-the-fact */
+      h4->ip4.src_address.as_u32 = t->tunnel_src.ip4.as_u32;
+      h4->ip4.dst_address.as_u32 = dst->ip4.as_u32;
+      h4->ip4.checksum = ip4_header_checksum (&h4->ip4);
+    }
+  else
+    {
+      vec_validate (rewrite, sizeof (*h6) - 1);
+      h6 = (ip6_and_gre_header_t *) rewrite;
+      gre = &h6->gre;
+      h6->ip6.ip_version_traffic_class_and_flow_label =
+	clib_host_to_net_u32 (6 << 28);
+      h6->ip6.hop_limit = 255;
+      h6->ip6.protocol = IP_PROTOCOL_GRE;
+      /* fixup ip6 header length and checksum after-the-fact */
+      h6->ip6.src_address.as_u64[0] = t->tunnel_src.ip6.as_u64[0];
+      h6->ip6.src_address.as_u64[1] = t->tunnel_src.ip6.as_u64[1];
+      h6->ip6.dst_address.as_u64[0] = dst->ip6.as_u64[0];
+      h6->ip6.dst_address.as_u64[1] = dst->ip6.as_u64[1];
+    }
+
+  if (PREDICT_FALSE (t->type == GRE_TUNNEL_TYPE_ERSPAN))
+    {
+      gre->protocol = clib_host_to_net_u16 (GRE_PROTOCOL_erspan);
+      gre->flags_and_version = clib_host_to_net_u16 (GRE_FLAGS_SEQUENCE);
+    }
+  else
+    gre->protocol =
+      clib_host_to_net_u16 (gre_proto_from_vnet_link (link_type));
+
+  return (rewrite);
+}
+
+static void
+gre44_fixup (vlib_main_t *vm, const ip_adjacency_t *adj, vlib_buffer_t *b0,
+	     const void *data)
+{
+  tunnel_encap_decap_flags_t flags;
+  ip4_and_gre_header_t *ip0;
+
+  ip0 = vlib_buffer_get_current (b0);
+  flags = pointer_to_uword (data);
+
+  /* Fixup the checksum and len fields in the GRE tunnel encap
+   * that was applied at the midchain node */
+  ip0->ip4.length =
+    clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
+  tunnel_encap_fixup_4o4 (flags, (ip4_header_t *) (ip0 + 1), &ip0->ip4);
+  ip0->ip4.checksum = ip4_header_checksum (&ip0->ip4);
+}
+
+static void
+gre64_fixup (vlib_main_t *vm, const ip_adjacency_t *adj, vlib_buffer_t *b0,
+	     const void *data)
+{
+  tunnel_encap_decap_flags_t flags;
+  ip4_and_gre_header_t *ip0;
+
+  ip0 = vlib_buffer_get_current (b0);
+  flags = pointer_to_uword (data);
+
+  /* Fixup the checksum and len fields in the GRE tunnel encap
+   * that was applied at the midchain node */
+  ip0->ip4.length =
+    clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
+  tunnel_encap_fixup_6o4 (flags, (ip6_header_t *) (ip0 + 1), &ip0->ip4);
+  ip0->ip4.checksum = ip4_header_checksum (&ip0->ip4);
+}
+
+static void
+grex4_fixup (vlib_main_t *vm, const ip_adjacency_t *adj, vlib_buffer_t *b0,
+	     const void *data)
+{
+  ip4_header_t *ip0;
+
+  ip0 = vlib_buffer_get_current (b0);
+
+  /* Fixup the checksum and len fields in the GRE tunnel encap
+   * that was applied at the midchain node */
+  ip0->length = clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
+  ip0->checksum = ip4_header_checksum (ip0);
+}
+
+static void
+gre46_fixup (vlib_main_t *vm, const ip_adjacency_t *adj, vlib_buffer_t *b0,
+	     const void *data)
+{
+  tunnel_encap_decap_flags_t flags;
+  ip6_and_gre_header_t *ip0;
+
+  ip0 = vlib_buffer_get_current (b0);
+  flags = pointer_to_uword (data);
+
+  /* Fixup the payload length field in the GRE tunnel encap that was applied
+   * at the midchain node */
+  ip0->ip6.payload_length = clib_host_to_net_u16 (
+    vlib_buffer_length_in_chain (vm, b0) - sizeof (ip0->ip6));
+  tunnel_encap_fixup_4o6 (flags, b0, (ip4_header_t *) (ip0 + 1), &ip0->ip6);
+}
+
+static void
+gre66_fixup (vlib_main_t *vm, const ip_adjacency_t *adj, vlib_buffer_t *b0,
+	     const void *data)
+{
+  tunnel_encap_decap_flags_t flags;
+  ip6_and_gre_header_t *ip0;
+
+  ip0 = vlib_buffer_get_current (b0);
+  flags = pointer_to_uword (data);
+
+  /* Fixup the payload length field in the GRE tunnel encap that was applied
+   * at the midchain node */
+  ip0->ip6.payload_length = clib_host_to_net_u16 (
+    vlib_buffer_length_in_chain (vm, b0) - sizeof (ip0->ip6));
+  tunnel_encap_fixup_6o6 (flags, (ip6_header_t *) (ip0 + 1), &ip0->ip6);
+}
+
+static void
+grex6_fixup (vlib_main_t *vm, const ip_adjacency_t *adj, vlib_buffer_t *b0,
+	     const void *data)
+{
+  ip6_and_gre_header_t *ip0;
+
+  ip0 = vlib_buffer_get_current (b0);
+
+  /* Fixup the payload length field in the GRE tunnel encap that was applied
+   * at the midchain node */
+  ip0->ip6.payload_length = clib_host_to_net_u16 (
+    vlib_buffer_length_in_chain (vm, b0) - sizeof (ip0->ip6));
+}
+
+/**
+ * return the appropriate fixup function given the overlay (link-type) and
+ * underlay (fproto) combination
+ */
+static adj_midchain_fixup_t
+gre_get_fixup (fib_protocol_t fproto, vnet_link_t lt)
+{
+  if (fproto == FIB_PROTOCOL_IP6 && lt == VNET_LINK_IP6)
+    return (gre66_fixup);
+  if (fproto == FIB_PROTOCOL_IP6 && lt == VNET_LINK_IP4)
+    return (gre46_fixup);
+  if (fproto == FIB_PROTOCOL_IP4 && lt == VNET_LINK_IP6)
+    return (gre64_fixup);
+  if (fproto == FIB_PROTOCOL_IP4 && lt == VNET_LINK_IP4)
+    return (gre44_fixup);
+  if (fproto == FIB_PROTOCOL_IP6)
+    return (grex6_fixup);
+  if (fproto == FIB_PROTOCOL_IP4)
+    return (grex4_fixup);
+
+  ASSERT (0);
+  return (gre44_fixup);
+}
+
+void
+gre_update_adj (vnet_main_t *vnm, u32 sw_if_index, adj_index_t ai)
+{
+  gre_main_t *gm = &gre_main;
+  gre_tunnel_t *t;
+  adj_flags_t af;
+  u32 ti;
+
+  ti = gm->tunnel_index_by_sw_if_index[sw_if_index];
+  t = pool_elt_at_index (gm->tunnels, ti);
+  af = ADJ_FLAG_NONE;
+
+  /*
+   * the user has not requested that the load-balancing be based on
+   * a flow hash of the inner packet. so use the stacking to choose
+   * a path.
+   */
+  if (!(t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH))
+    af |= ADJ_FLAG_MIDCHAIN_IP_STACK;
+
+  adj_nbr_midchain_update_rewrite (
+    ai, gre_get_fixup (t->tunnel_dst.fp_proto, adj_get_link_type (ai)),
+    uword_to_pointer (t->flags, void *), af,
+    gre_build_rewrite (vnm, sw_if_index, adj_get_link_type (ai),
+		       &t->tunnel_dst.fp_addr));
+
+  gre_tunnel_stack (ai);
+}
+
+adj_walk_rc_t
+mgre_mk_complete_walk (adj_index_t ai, void *data)
+{
+  mgre_walk_ctx_t *ctx = data;
+  adj_flags_t af;
+
+  af = ADJ_FLAG_NONE;
+
+  /*
+   * the user has not requested that the load-balancing be based on
+   * a flow hash of the inner packet. so use the stacking to choose
+   * a path.
+   */
+  if (!(ctx->t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH))
+    af |= ADJ_FLAG_MIDCHAIN_IP_STACK;
+
+  adj_nbr_midchain_update_rewrite (
+    ai, gre_get_fixup (ctx->t->tunnel_dst.fp_proto, adj_get_link_type (ai)),
+    uword_to_pointer (ctx->t->flags, void *), af,
+    gre_build_rewrite (vnet_get_main (), ctx->t->sw_if_index,
+		       adj_get_link_type (ai),
+		       &teib_entry_get_nh (ctx->ne)->fp_addr));
+
+  teib_entry_adj_stack (ctx->ne, ai);
+
+  return (ADJ_WALK_RC_CONTINUE);
+}
+
+adj_walk_rc_t
+mgre_mk_incomplete_walk (adj_index_t ai, void *data)
+{
+  gre_tunnel_t *t = data;
+
+  adj_nbr_midchain_update_rewrite (
+    ai, gre_get_fixup (t->tunnel_dst.fp_proto, adj_get_link_type (ai)), NULL,
+    ADJ_FLAG_NONE, NULL);
+
+  adj_midchain_delegate_unstack (ai);
+
+  return (ADJ_WALK_RC_CONTINUE);
+}
+
+void
+mgre_update_adj (vnet_main_t *vnm, u32 sw_if_index, adj_index_t ai)
+{
+  gre_main_t *gm = &gre_main;
+  ip_adjacency_t *adj;
+  teib_entry_t *ne;
+  gre_tunnel_t *t;
+  u32 ti;
+
+  adj = adj_get (ai);
+  ti = gm->tunnel_index_by_sw_if_index[sw_if_index];
+  t = pool_elt_at_index (gm->tunnels, ti);
+
+  ne = teib_entry_find_46 (sw_if_index, adj->ia_nh_proto,
+			   &adj->sub_type.nbr.next_hop);
+
+  if (NULL == ne)
+    {
+      // no TEIB entry to provide the next-hop
+      adj_nbr_midchain_update_rewrite (
+	ai, gre_get_fixup (t->tunnel_dst.fp_proto, adj_get_link_type (ai)),
+	uword_to_pointer (t->flags, void *), ADJ_FLAG_NONE, NULL);
+      return;
+    }
+
+  mgre_walk_ctx_t ctx = { .t = t, .ne = ne };
+  adj_nbr_walk_nh (sw_if_index, adj->ia_nh_proto, &adj->sub_type.nbr.next_hop,
+		   mgre_mk_complete_walk, &ctx);
+}
+#endif /* CLIB_MARCH_VARIANT */
+
+typedef enum
+{
+  GRE_ENCAP_NEXT_L2_MIDCHAIN,
+  GRE_ENCAP_N_NEXT,
+} gre_encap_next_t;
+
+/**
+ * @brief TX function. Only called for L2 payload including TEB or ERSPAN.
+ *        L3 traffic uses the adj-midchains.
+ */
+static_always_inline u32
+gre_encap_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
+		  vlib_frame_t *frame, gre_tunnel_type_t type)
+{
+  gre_main_t *gm = &gre_main;
+  u32 *from, n_left_from;
+  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
+  u32 sw_if_index[2] = { ~0, ~0 };
+  const gre_tunnel_t *gt[2] = { 0 };
+  adj_index_t adj_index[2] = { ADJ_INDEX_INVALID, ADJ_INDEX_INVALID };
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  vlib_get_buffers (vm, from, bufs, n_left_from);
+
+  while (n_left_from >= 2)
+    {
+
+      if (PREDICT_FALSE (sw_if_index[0] !=
+			 vnet_buffer (b[0])->sw_if_index[VLIB_TX]))
+	{
+	  const vnet_hw_interface_t *hi;
+	  sw_if_index[0] = vnet_buffer (b[0])->sw_if_index[VLIB_TX];
+	  hi = vnet_get_sup_hw_interface (gm->vnet_main, sw_if_index[0]);
+	  gt[0] = &gm->tunnels[hi->dev_instance];
+	  adj_index[0] = gt[0]->l2_adj_index;
+	}
+      if (PREDICT_FALSE (sw_if_index[1] !=
+			 vnet_buffer (b[1])->sw_if_index[VLIB_TX]))
+	{
+	  const vnet_hw_interface_t *hi;
+	  sw_if_index[1] = vnet_buffer (b[1])->sw_if_index[VLIB_TX];
+	  hi = vnet_get_sup_hw_interface (gm->vnet_main, sw_if_index[1]);
+	  gt[1] = &gm->tunnels[hi->dev_instance];
+	  adj_index[1] = gt[1]->l2_adj_index;
+	}
+
+      vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = adj_index[0];
+      vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = adj_index[1];
+
+      if (type == GRE_TUNNEL_TYPE_ERSPAN)
+	{
+	  /* Encap GRE seq# and ERSPAN type II header */
+	  erspan_t2_t *h0;
+	  u32 seq_num;
+	  u64 hdr;
+	  vlib_buffer_advance (b[0], -sizeof (erspan_t2_t));
+	  h0 = vlib_buffer_get_current (b[0]);
+	  seq_num = clib_atomic_fetch_add (&gt[0]->gre_sn->seq_num, 1);
+	  hdr = clib_host_to_net_u64 (ERSPAN_HDR2);
+	  h0->seq_num = clib_host_to_net_u32 (seq_num);
+	  h0->t2_u64 = hdr;
+	  h0->t2.cos_en_t_session |= clib_host_to_net_u16 (gt[0]->session_id);
+	}
+      if (type == GRE_TUNNEL_TYPE_ERSPAN)
+	{
+	  /* Encap GRE seq# and ERSPAN type II header */
+	  erspan_t2_t *h0;
+	  u32 seq_num;
+	  u64 hdr;
+	  vlib_buffer_advance (b[1], -sizeof (erspan_t2_t));
+	  h0 = vlib_buffer_get_current (b[1]);
+	  seq_num = clib_atomic_fetch_add (&gt[1]->gre_sn->seq_num, 1);
+	  hdr = clib_host_to_net_u64 (ERSPAN_HDR2);
+	  h0->seq_num = clib_host_to_net_u32 (seq_num);
+	  h0->t2_u64 = hdr;
+	  h0->t2.cos_en_t_session |= clib_host_to_net_u16 (gt[1]->session_id);
+	}
+
+      if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
+	{
+	  gre_tx_trace_t *tr = vlib_add_trace (vm, node, b[0], sizeof (*tr));
+	  tr->tunnel_id = gt[0] - gm->tunnels;
+	  tr->src = gt[0]->tunnel_src;
+	  tr->dst = gt[0]->tunnel_dst.fp_addr;
+	  tr->length = vlib_buffer_length_in_chain (vm, b[0]);
+	}
+      if (PREDICT_FALSE (b[1]->flags & VLIB_BUFFER_IS_TRACED))
+	{
+	  gre_tx_trace_t *tr = vlib_add_trace (vm, node, b[1], sizeof (*tr));
+	  tr->tunnel_id = gt[1] - gm->tunnels;
+	  tr->src = gt[1]->tunnel_src;
+	  tr->dst = gt[1]->tunnel_dst.fp_addr;
+	  tr->length = vlib_buffer_length_in_chain (vm, b[1]);
+	}
+
+      b += 2;
+      n_left_from -= 2;
+    }
+
+  while (n_left_from >= 1)
+    {
+
+      if (PREDICT_FALSE (sw_if_index[0] !=
+			 vnet_buffer (b[0])->sw_if_index[VLIB_TX]))
+	{
+	  const vnet_hw_interface_t *hi;
+	  sw_if_index[0] = vnet_buffer (b[0])->sw_if_index[VLIB_TX];
+	  hi = vnet_get_sup_hw_interface (gm->vnet_main, sw_if_index[0]);
+	  gt[0] = &gm->tunnels[hi->dev_instance];
+	  adj_index[0] = gt[0]->l2_adj_index;
+	}
+
+      vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = adj_index[0];
+
+      if (type == GRE_TUNNEL_TYPE_ERSPAN)
+	{
+	  /* Encap GRE seq# and ERSPAN type II header */
+	  erspan_t2_t *h0;
+	  u32 seq_num;
+	  u64 hdr;
+	  ASSERT (gt[0]->type == GRE_TUNNEL_TYPE_ERSPAN);
+	  vlib_buffer_advance (b[0], -sizeof (erspan_t2_t));
+	  h0 = vlib_buffer_get_current (b[0]);
+	  seq_num = clib_atomic_fetch_add (&gt[0]->gre_sn->seq_num, 1);
+	  hdr = clib_host_to_net_u64 (ERSPAN_HDR2);
+	  h0->seq_num = clib_host_to_net_u32 (seq_num);
+	  h0->t2_u64 = hdr;
+	  h0->t2.cos_en_t_session |= clib_host_to_net_u16 (gt[0]->session_id);
+	}
+
+      if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
+	{
+	  gre_tx_trace_t *tr = vlib_add_trace (vm, node, b[0], sizeof (*tr));
+	  tr->tunnel_id = gt[0] - gm->tunnels;
+	  tr->src = gt[0]->tunnel_src;
+	  tr->dst = gt[0]->tunnel_dst.fp_addr;
+	  tr->length = vlib_buffer_length_in_chain (vm, b[0]);
+	}
+
+      b += 1;
+      n_left_from -= 1;
+    }
+
+  vlib_buffer_enqueue_to_single_next (
+    vm, node, from, GRE_ENCAP_NEXT_L2_MIDCHAIN, frame->n_vectors);
+
+  vlib_node_increment_counter (vm, node->node_index, GRE_ERROR_PKTS_ENCAP,
+			       frame->n_vectors);
+
+  return frame->n_vectors;
+}
+
+static char *gre_error_strings[] = {
+#define gre_error(n, s) s,
+#include "error.def"
+#undef gre_error
+};
+
+VLIB_NODE_FN (gre_teb_encap_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  return (gre_encap_inline (vm, node, frame, GRE_TUNNEL_TYPE_TEB));
+}
+
+VLIB_NODE_FN (gre_erspan_encap_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  return (gre_encap_inline (vm, node, frame, GRE_TUNNEL_TYPE_ERSPAN));
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (gre_teb_encap_node) =
+{
+  .name = "gre-teb-encap",
+  .vector_size = sizeof (u32),
+  .format_trace = format_gre_tx_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = GRE_N_ERROR,
+  .error_strings = gre_error_strings,
+  .n_next_nodes = GRE_ENCAP_N_NEXT,
+  .next_nodes = {
+    [GRE_ENCAP_NEXT_L2_MIDCHAIN] = "adj-l2-midchain",
+  },
+};
+VLIB_REGISTER_NODE (gre_erspan_encap_node) =
+{
+  .name = "gre-erspan-encap",
+  .vector_size = sizeof (u32),
+  .format_trace = format_gre_tx_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = GRE_N_ERROR,
+  .error_strings = gre_error_strings,
+  .n_next_nodes = GRE_ENCAP_N_NEXT,
+  .next_nodes = {
+    [GRE_ENCAP_NEXT_L2_MIDCHAIN] = "adj-l2-midchain",
+  },
+};
+/* *INDENT-ON* */
+
+#ifndef CLIB_MARCH_VARIANT
+static u8 *
+format_gre_tunnel_name (u8 *s, va_list *args)
+{
+  u32 dev_instance = va_arg (*args, u32);
+  gre_main_t *gm = &gre_main;
+  gre_tunnel_t *t;
+
+  if (dev_instance >= vec_len (gm->tunnels))
+    return format (s, "<improperly-referenced>");
+
+  t = pool_elt_at_index (gm->tunnels, dev_instance);
+  return format (s, "gre%d", t->user_instance);
+}
+
+static u8 *
+format_gre_device (u8 *s, va_list *args)
+{
+  u32 dev_instance = va_arg (*args, u32);
+  CLIB_UNUSED (int verbose) = va_arg (*args, int);
+
+  s = format (s, "GRE tunnel: id %d\n", dev_instance);
+  return s;
+}
+
+static int
+gre_tunnel_desc (u32 sw_if_index, ip46_address_t *src, ip46_address_t *dst,
+		 u8 *is_l2)
+{
+  gre_main_t *gm = &gre_main;
+  gre_tunnel_t *t;
+  u32 ti;
+
+  ti = gm->tunnel_index_by_sw_if_index[sw_if_index];
+
+  if (~0 == ti)
+    /* not one of ours */
+    return -1;
+
+  t = pool_elt_at_index (gm->tunnels, ti);
+
+  *src = t->tunnel_src;
+  *dst = t->tunnel_dst.fp_addr;
+  *is_l2 = t->type == GRE_TUNNEL_TYPE_TEB;
+
+  return (0);
+}
+
+/* *INDENT-OFF* */
+VNET_DEVICE_CLASS (gre_device_class) = {
+  .name = "GRE tunnel device",
+  .format_device_name = format_gre_tunnel_name,
+  .format_device = format_gre_device,
+  .format_tx_trace = format_gre_tx_trace,
+  .admin_up_down_function = gre_interface_admin_up_down,
+  .ip_tun_desc = gre_tunnel_desc,
+#ifdef SOON
+  .clear counter = 0;
+#endif
+}
+;
+
+VNET_HW_INTERFACE_CLASS (gre_hw_interface_class) = {
+  .name = "GRE",
+  .format_header = format_gre_header_with_length,
+  .unformat_header = unformat_gre_header,
+  .build_rewrite = gre_build_rewrite,
+  .update_adjacency = gre_update_adj,
+  .flags = VNET_HW_INTERFACE_CLASS_FLAG_P2P,
+};
+
+VNET_HW_INTERFACE_CLASS (mgre_hw_interface_class) = {
+  .name = "mGRE",
+  .format_header = format_gre_header_with_length,
+  .unformat_header = unformat_gre_header,
+  .build_rewrite = gre_build_rewrite,
+  .update_adjacency = mgre_update_adj,
+  .flags = VNET_HW_INTERFACE_CLASS_FLAG_NBMA,
+};
+/* *INDENT-ON* */
+#endif /* CLIB_MARCH_VARIANT */
+
+static void
+add_protocol (gre_main_t *gm, gre_protocol_t protocol, char *protocol_name)
+{
+  gre_protocol_info_t *pi;
+  u32 i;
+
+  vec_add2 (gm->protocol_infos, pi, 1);
+  i = pi - gm->protocol_infos;
+
+  pi->name = protocol_name;
+  pi->protocol = protocol;
+  pi->next_index = pi->node_index = ~0;
+
+  hash_set (gm->protocol_info_by_protocol, protocol, i);
+  hash_set_mem (gm->protocol_info_by_name, pi->name, i);
+}
+
+static clib_error_t *
+gre_init (vlib_main_t *vm)
+{
+  gre_main_t *gm = &gre_main;
+  clib_error_t *error;
+  ip_main_t *im = &ip_main;
+  ip_protocol_info_t *pi;
+
+  clib_memset (gm, 0, sizeof (gm[0]));
+  gm->vlib_main = vm;
+  gm->vnet_main = vnet_get_main ();
+
+  if ((error = vlib_call_init_function (vm, ip_main_init)))
+    return error;
+
+  if ((error = vlib_call_init_function (vm, ip4_lookup_init)))
+    return error;
+
+  if ((error = vlib_call_init_function (vm, ip6_lookup_init)))
+    return error;
+
+  /* Set up the ip packet generator */
+  pi = ip_get_protocol_info (im, IP_PROTOCOL_GRE);
+  pi->format_header = format_gre_header;
+  pi->unformat_pg_edit = unformat_pg_gre_header;
+
+  gm->protocol_info_by_name = hash_create_string (0, sizeof (uword));
+  gm->protocol_info_by_protocol = hash_create (0, sizeof (uword));
+  gm->tunnel_by_key4 =
+    hash_create_mem (0, sizeof (gre_tunnel_key4_t), sizeof (uword));
+  gm->tunnel_by_key6 =
+    hash_create_mem (0, sizeof (gre_tunnel_key6_t), sizeof (uword));
+  gm->seq_num_by_key =
+    hash_create_mem (0, sizeof (gre_sn_key_t), sizeof (uword));
+
+#define _(n, s) add_protocol (gm, GRE_PROTOCOL_##s, #s);
+  foreach_gre_protocol
+#undef _
+    return vlib_call_init_function (vm, gre_input_init);
+}
+
+VLIB_INIT_FUNCTION (gre_init);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */