src/vnet/cdp/cdp_periodic.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2011-2016 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/cdp/cdp_node.h>
 #include <vppinfra/hash.h>
 #include <vnet/unix/pcap.h>
 #include <vnet/srp/srp.h>
 #include <vnet/ppp/ppp.h>
 #include <vnet/hdlc/hdlc.h>
 #include <vnet/srp/packet.h>

 /*
  * Generate a set of specific CDP TLVs.
  *
  * $$$ eventually these need to fish better data from
  * other data structures; e.g. the hostname, software version info
  * etc.
  */

 static void
 add_device_name_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
 {
   cdp_tlv_t *t = (cdp_tlv_t *) * t0p;

   t->t = htons (CDP_TLV_device_name);
   t->l = htons (3 + sizeof (*t));
   clib_memcpy (&t->v, "VPP", 3);

   *t0p += ntohs (t->l);
 }

 static void
 add_port_id_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
 {
   cdp_tlv_t *t = (cdp_tlv_t *) * t0p;

   t->t = htons (CDP_TLV_port_id);
   t->l = htons (vec_len (hw->name) + sizeof (*t));
   clib_memcpy (&t->v, hw->name, vec_len (hw->name));
   *t0p += ntohs (t->l);
 }

 static void
 add_version_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
 {
   cdp_tlv_t *t = (cdp_tlv_t *) * t0p;

   t->t = htons (CDP_TLV_version);
   t->l = htons (12 + sizeof (*t));
   clib_memcpy (&t->v, "VPP Software", 12);
   *t0p += ntohs (t->l);
 }

 static void
 add_platform_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
 {
   cdp_tlv_t *t = (cdp_tlv_t *) * t0p;

   t->t = htons (CDP_TLV_platform);
   t->l = htons (2 + sizeof (*t));
   clib_memcpy (&t->v, "SW", 2);
   *t0p += ntohs (t->l);
 }

 static void
 add_capability_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
 {
   cdp_tlv_t *t = (cdp_tlv_t *) * t0p;
   u32 capabilities;

   t->t = htons (CDP_TLV_capabilities);
   t->l = htons (4 + sizeof (*t));
   capabilities = CDP_ROUTER_DEVICE;
   capabilities = htonl (capabilities);
   clib_memcpy (&t->v, &capabilities, sizeof (capabilities));
   *t0p += ntohs (t->l);
 }

 static void
 add_tlvs (cdp_main_t * cm, vnet_hw_interface_t * hw, u8 ** t0p)
 {
   add_device_name_tlv (hw, t0p);
   add_port_id_tlv (hw, t0p);
   add_version_tlv (hw, t0p);
   add_platform_tlv (hw, t0p);
   add_capability_tlv (hw, t0p);
 }

 /*
  * send a cdp pkt on an ethernet interface
  */
 static void
 send_ethernet_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
 {
   u32 *to_next;
   ethernet_llc_snap_and_cdp_header_t *h0;
   vnet_hw_interface_t *hw;
   u32 bi0;
   vlib_buffer_t *b0;
   u8 *t0;
   u16 checksum;
   int nbytes_to_checksum;
   int i;
   vlib_frame_t *f;
   vlib_main_t *vm = cm->vlib_main;
   vnet_main_t *vnm = cm->vnet_main;

   for (i = 0; i < count; i++)
     {
       /*
        * see cdp_periodic_init() to understand what's already painted
        * into the buffer by the packet template mechanism
        */
       h0 = vlib_packet_template_get_packet
 	(vm, &cm->packet_templates[n->packet_template_index], &bi0);

       if (!h0)
 	break;

       /* Add the interface's ethernet source address */
       hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

       clib_memcpy (h0->ethernet.src_address, hw->hw_address,
 		   vec_len (hw->hw_address));

       t0 = (u8 *) & h0->cdp.data;

       /* add TLVs */
       add_tlvs (cm, hw, &t0);

       /* add the cdp packet checksum */
       nbytes_to_checksum = t0 - (u8 *) & h0->cdp;
       checksum = cdp_checksum (&h0->cdp, nbytes_to_checksum);
       h0->cdp.checksum = htons (checksum);

       /* Set the outbound packet length */
       b0 = vlib_get_buffer (vm, bi0);
       b0->current_length = nbytes_to_checksum + sizeof (*h0)
 	- sizeof (cdp_hdr_t);

       /* And the outbound interface */
       vnet_buffer (b0)->sw_if_index[VLIB_TX] = hw->sw_if_index;

       /* Set the 802.3 ethernet length */
       h0->ethernet.len = htons (b0->current_length
 				- sizeof (ethernet_802_3_header_t));

       /* And output the packet on the correct interface */
       f = vlib_get_frame_to_node (vm, hw->output_node_index);
       to_next = vlib_frame_vector_args (f);
       to_next[0] = bi0;
       f->n_vectors = 1;

       vlib_put_frame_to_node (vm, hw->output_node_index, f);
       n->last_sent = vlib_time_now (vm);
     }
 }

 /*
  * send a cdp pkt on an hdlc interface
  */
 static void
 send_hdlc_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
 {
   u32 *to_next;
   hdlc_and_cdp_header_t *h0;
   vnet_hw_interface_t *hw;
   u32 bi0;
   vlib_buffer_t *b0;
   u8 *t0;
   u16 checksum;
   int nbytes_to_checksum;
   int i;
   vlib_frame_t *f;
   vlib_main_t *vm = cm->vlib_main;
   vnet_main_t *vnm = cm->vnet_main;

   for (i = 0; i < count; i++)
     {
       /*
        * see cdp_periodic_init() to understand what's already painted
        * into the buffer by the packet template mechanism
        */
       h0 = vlib_packet_template_get_packet
 	(vm, &cm->packet_templates[n->packet_template_index], &bi0);

       hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

       t0 = (u8 *) & h0->cdp.data;

       /* add TLVs */
       add_tlvs (cm, hw, &t0);

       /* add the cdp packet checksum */
       nbytes_to_checksum = t0 - (u8 *) & h0->cdp;
       checksum = cdp_checksum (&h0->cdp, nbytes_to_checksum);
       h0->cdp.checksum = htons (checksum);

       /* Set the outbound packet length */
       b0 = vlib_get_buffer (vm, bi0);
       b0->current_length = nbytes_to_checksum + sizeof (*h0)
 	- sizeof (cdp_hdr_t);

       /* And output the packet on the correct interface */
       f = vlib_get_frame_to_node (vm, hw->output_node_index);
       to_next = vlib_frame_vector_args (f);
       to_next[0] = bi0;
       f->n_vectors = 1;

       vlib_put_frame_to_node (vm, hw->output_node_index, f);
       n->last_sent = vlib_time_now (vm);
     }
 }

 /*
  * send a cdp pkt on an srp interface
  */
 static void
 send_srp_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
 {
   u32 *to_next;
   srp_and_cdp_header_t *h0;
   vnet_hw_interface_t *hw;
   u32 bi0;
   vlib_buffer_t *b0;
   u8 *t0;
   u16 checksum;
   int nbytes_to_checksum;
   int i;
   vlib_frame_t *f;
   vlib_main_t *vm = cm->vlib_main;
   vnet_main_t *vnm = cm->vnet_main;

   for (i = 0; i < count; i++)
     {
       /*
        * see cdp_periodic_init() to understand what's already painted
        * into the buffer by the packet template mechanism
        */
       h0 = vlib_packet_template_get_packet
 	(vm, &cm->packet_templates[n->packet_template_index], &bi0);

       hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

       t0 = (u8 *) & h0->cdp.data;

       /* add TLVs */
       add_tlvs (cm, hw, &t0);

       /* Add the interface's ethernet source address */
       clib_memcpy (h0->ethernet.src_address, hw->hw_address,
 		   vec_len (hw->hw_address));

       /* add the cdp packet checksum */
       nbytes_to_checksum = t0 - (u8 *) & h0->cdp;
       checksum = cdp_checksum (&h0->cdp, nbytes_to_checksum);
       h0->cdp.checksum = htons (checksum);

       /* Set the outbound packet length */
       b0 = vlib_get_buffer (vm, bi0);
       b0->current_length = nbytes_to_checksum + sizeof (*h0)
 	- sizeof (cdp_hdr_t);

       /* And output the packet on the correct interface */
       f = vlib_get_frame_to_node (vm, hw->output_node_index);
       to_next = vlib_frame_vector_args (f);
       to_next[0] = bi0;
       f->n_vectors = 1;

       vlib_put_frame_to_node (vm, hw->output_node_index, f);
       n->last_sent = vlib_time_now (vm);
     }
 }

 /*
  * Decide which cdp packet template to use
  */
 static int
 pick_packet_template (cdp_main_t * cm, cdp_neighbor_t * n)
 {
   n->packet_template_index = CDP_PACKET_TEMPLATE_ETHERNET;

   return 0;
 }

 /* Send a cdp neighbor announcement */
 static void
 send_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
 {
   if (n->packet_template_index == (u8) ~ 0)
     {
       /* If we don't know how to talk to this peer, don't try again */
       if (pick_packet_template (cm, n))
 	{
 	  n->last_sent = 1e70;
 	  return;
 	}
     }

   switch (n->packet_template_index)
     {
     case CDP_PACKET_TEMPLATE_ETHERNET:
       send_ethernet_hello (cm, n, count);
       break;

     case CDP_PACKET_TEMPLATE_HDLC:
       send_hdlc_hello (cm, n, count);
       break;

     case CDP_PACKET_TEMPLATE_SRP:
       send_srp_hello (cm, n, count);
       break;

     default:
       ASSERT (0);
     }
   n->last_sent = vlib_time_now (cm->vlib_main);
 }

 static void
 delete_neighbor (cdp_main_t * cm, cdp_neighbor_t * n, int want_broadcast)
 {
   hash_unset (cm->neighbor_by_sw_if_index, n->sw_if_index);
   vec_free (n->device_name);
   vec_free (n->version);
   vec_free (n->port_id);
   vec_free (n->platform);
   vec_free (n->last_rx_pkt);
   pool_put (cm->neighbors, n);
 }

 void
 cdp_periodic (vlib_main_t * vm)
 {
   cdp_main_t *cm = &cdp_main;
   cdp_neighbor_t *n;
   f64 now = vlib_time_now (vm);
   vnet_sw_interface_t *sw;
   static u32 *delete_list = 0;
   int i;
   static cdp_neighbor_t **n_list = 0;

   /* *INDENT-OFF* */
   pool_foreach (n, cm->neighbors,
   ({
     vec_add1 (n_list, n);
   }));
   /* *INDENT-ON* */

   /* Across all cdp neighbors known to the system */
   for (i = 0; i < vec_len (n_list); i++)
     {
       n = n_list[i];

       /* "no cdp run" provisioned on the interface? */
       if (n->disabled == 1)
 	continue;

       sw = vnet_get_sw_interface (cm->vnet_main, n->sw_if_index);

       /* Interface shutdown or rx timeout? */
       if (!(sw->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
 	  || (now > (n->last_heard + (f64) n->ttl_in_seconds)))
 	/* add to list of neighbors to delete */
 	vec_add1 (delete_list, n - cm->neighbors);
       else if (n->last_sent == 0.0)
 	/* First time, send 3 hellos */
 	send_hello (cm, n, 3 /* three to begin with */ );
       else if (now > (n->last_sent + (((f64) n->ttl_in_seconds) / 6.0)))
 	/* Normal keepalive, send one */
 	send_hello (cm, n, 1 /* one as a keepalive */ );
     }

   for (i = 0; i < vec_len (delete_list); i++)
     {
       n = vec_elt_at_index (cm->neighbors, delete_list[i]);
       delete_neighbor (cm, n, 1);
     }
   if (delete_list)
     _vec_len (delete_list) = 0;
   if (n_list)
     _vec_len (n_list) = 0;
 }

 static clib_error_t *
 cdp_periodic_init (vlib_main_t * vm)
 {
   cdp_main_t *cm = &cdp_main;

   /* Create the ethernet cdp hello packet template */
   {
     ethernet_llc_snap_and_cdp_header_t h;

     memset (&h, 0, sizeof (h));

     /* Send to 01:00:0c:cc:cc */
     h.ethernet.dst_address[0] = 0x01;
     /* h.ethernet.dst_address[1] = 0x00; (memset) */
     h.ethernet.dst_address[2] = 0x0C;
     h.ethernet.dst_address[3] = 0xCC;
     h.ethernet.dst_address[4] = 0xCC;
     h.ethernet.dst_address[5] = 0xCC;

     /* leave src address blank (fill in at send time) */

     /* leave length blank (fill in at send time) */

     /* LLC */
     h.llc.dst_sap = h.llc.src_sap = 0xAA;	/* SNAP */
     h.llc.control = 0x03;	/* UI (no extended control bytes) */

     /* SNAP */
     /* h.snap.oui[0] = 0x00; (memset) */
     /* h.snap.oui[1] = 0x00; (memset) */
     h.snap.oui[2] = 0x0C;	/* Cisco = 0x00000C */
     h.snap.protocol = htons (0x2000);	/* CDP = 0x2000 */

     /* CDP */
     h.cdp.version = 2;
     h.cdp.ttl = 180;

     vlib_packet_template_init
       (vm, &cm->packet_templates[CDP_PACKET_TEMPLATE_ETHERNET],
        /* data */ &h,
        sizeof (h),
        /* alloc chunk size */ 8,
        "cdp-ethernet");
   }

 #if 0				/* retain for reference */

   /* Create the hdlc cdp hello packet template */
   {
     hdlc_and_cdp_header_t h;

     memset (&h, 0, sizeof (h));

     h.hdlc.address = 0x0f;
     /* h.hdlc.control = 0; (memset) */
     h.hdlc.protocol = htons (0x2000);	/* CDP = 0x2000 */

     /* CDP */
     h.cdp.version = 2;
     h.cdp.ttl = 180;

     vlib_packet_template_init
       (vm, &cm->packet_templates[CDP_PACKET_TEMPLATE_HDLC],
        /* data */ &h,
        sizeof (h),
        /* alloc chunk size */ 8,
        "cdp-hdlc");
   }

   /* Create the srp cdp hello packet template */
   {
     srp_and_cdp_header_t h;

     memset (&h, 0, sizeof (h));

     /* Send to 01:00:0c:cc:cc */
     h.ethernet.dst_address[0] = 0x01;
     /* h.ethernet.dst_address[1] = 0x00; (memset) */
     h.ethernet.dst_address[2] = 0x0C;
     h.ethernet.dst_address[3] = 0xCC;
     h.ethernet.dst_address[4] = 0xCC;
     h.ethernet.dst_address[5] = 0xCC;

     /* leave src address blank (fill in at send time) */

     /* The srp header is filled in at xmt */
     h.srp.ttl = 1;
     h.srp.priority = 7;
     h.srp.mode = SRP_MODE_data;
     srp_header_compute_parity (&h.srp);

     /* Inner ring and parity will be set at send time */

     h.ethernet.type = htons (0x2000);	/* CDP = 0x2000 */

     /* CDP */
     h.cdp.version = 2;
     h.cdp.ttl = 180;

     vlib_packet_template_init
       (vm, &cm->packet_templates[CDP_PACKET_TEMPLATE_SRP],
        /* data */ &h,
        sizeof (h),
        /* alloc chunk size */ 8,
        "cdp-srp");
   }
 #endif

   return 0;
 }

 VLIB_INIT_FUNCTION (cdp_periodic_init);

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2011-2016 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/cdp/cdp_node.h>
	#include <vppinfra/hash.h>
	#include <vnet/unix/pcap.h>
	#include <vnet/srp/srp.h>
	#include <vnet/ppp/ppp.h>
	#include <vnet/hdlc/hdlc.h>
	#include <vnet/srp/packet.h>

	/*
	* Generate a set of specific CDP TLVs.
	*
	* $$$ eventually these need to fish better data from
	* other data structures; e.g. the hostname, software version info
	* etc.
	*/

	static void
	add_device_name_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
	{
	cdp_tlv_t t = (cdp_tlv_t ) * t0p;

	t->t = htons (CDP_TLV_device_name);
	t->l = htons (3 + sizeof (*t));
	clib_memcpy (&t->v, "VPP", 3);

	*t0p += ntohs (t->l);
	}

	static void
	add_port_id_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
	{
	cdp_tlv_t t = (cdp_tlv_t ) * t0p;

	t->t = htons (CDP_TLV_port_id);
	t->l = htons (vec_len (hw->name) + sizeof (*t));
	clib_memcpy (&t->v, hw->name, vec_len (hw->name));
	*t0p += ntohs (t->l);
	}

	static void
	add_version_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
	{
	cdp_tlv_t t = (cdp_tlv_t ) * t0p;

	t->t = htons (CDP_TLV_version);
	t->l = htons (12 + sizeof (*t));
	clib_memcpy (&t->v, "VPP Software", 12);
	*t0p += ntohs (t->l);
	}

	static void
	add_platform_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
	{
	cdp_tlv_t t = (cdp_tlv_t ) * t0p;

	t->t = htons (CDP_TLV_platform);
	t->l = htons (2 + sizeof (*t));
	clib_memcpy (&t->v, "SW", 2);
	*t0p += ntohs (t->l);
	}

	static void
	add_capability_tlv (vnet_hw_interface_t * hw, u8 ** t0p)
	{
	cdp_tlv_t t = (cdp_tlv_t ) * t0p;
	u32 capabilities;

	t->t = htons (CDP_TLV_capabilities);
	t->l = htons (4 + sizeof (*t));
	capabilities = CDP_ROUTER_DEVICE;
	capabilities = htonl (capabilities);
	clib_memcpy (&t->v, &capabilities, sizeof (capabilities));
	*t0p += ntohs (t->l);
	}

	static void
	add_tlvs (cdp_main_t * cm, vnet_hw_interface_t * hw, u8 ** t0p)
	{
	add_device_name_tlv (hw, t0p);
	add_port_id_tlv (hw, t0p);
	add_version_tlv (hw, t0p);
	add_platform_tlv (hw, t0p);
	add_capability_tlv (hw, t0p);
	}

	/*
	* send a cdp pkt on an ethernet interface
	*/
	static void
	send_ethernet_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
	{
	u32 *to_next;
	ethernet_llc_snap_and_cdp_header_t *h0;
	vnet_hw_interface_t *hw;
	u32 bi0;
	vlib_buffer_t *b0;
	u8 *t0;
	u16 checksum;
	int nbytes_to_checksum;
	int i;
	vlib_frame_t *f;
	vlib_main_t *vm = cm->vlib_main;
	vnet_main_t *vnm = cm->vnet_main;

	for (i = 0; i < count; i++)
	{
	/*
	* see cdp_periodic_init() to understand what's already painted
	* into the buffer by the packet template mechanism
	*/
	h0 = vlib_packet_template_get_packet
	(vm, &cm->packet_templates[n->packet_template_index], &bi0);

	if (!h0)
	break;

	/* Add the interface's ethernet source address */
	hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

	clib_memcpy (h0->ethernet.src_address, hw->hw_address,
	vec_len (hw->hw_address));

	t0 = (u8 *) & h0->cdp.data;

	/* add TLVs */
	add_tlvs (cm, hw, &t0);

	/* add the cdp packet checksum */
	nbytes_to_checksum = t0 - (u8 *) & h0->cdp;
	checksum = cdp_checksum (&h0->cdp, nbytes_to_checksum);
	h0->cdp.checksum = htons (checksum);

	/* Set the outbound packet length */
	b0 = vlib_get_buffer (vm, bi0);
	b0->current_length = nbytes_to_checksum + sizeof (*h0)
	- sizeof (cdp_hdr_t);

	/* And the outbound interface */
	vnet_buffer (b0)->sw_if_index[VLIB_TX] = hw->sw_if_index;

	/* Set the 802.3 ethernet length */
	h0->ethernet.len = htons (b0->current_length
	- sizeof (ethernet_802_3_header_t));

	/* And output the packet on the correct interface */
	f = vlib_get_frame_to_node (vm, hw->output_node_index);
	to_next = vlib_frame_vector_args (f);
	to_next[0] = bi0;
	f->n_vectors = 1;

	vlib_put_frame_to_node (vm, hw->output_node_index, f);
	n->last_sent = vlib_time_now (vm);
	}
	}

	/*
	* send a cdp pkt on an hdlc interface
	*/
	static void
	send_hdlc_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
	{
	u32 *to_next;
	hdlc_and_cdp_header_t *h0;
	vnet_hw_interface_t *hw;
	u32 bi0;
	vlib_buffer_t *b0;
	u8 *t0;
	u16 checksum;
	int nbytes_to_checksum;
	int i;
	vlib_frame_t *f;
	vlib_main_t *vm = cm->vlib_main;
	vnet_main_t *vnm = cm->vnet_main;

	for (i = 0; i < count; i++)
	{
	/*
	* see cdp_periodic_init() to understand what's already painted
	* into the buffer by the packet template mechanism
	*/
	h0 = vlib_packet_template_get_packet
	(vm, &cm->packet_templates[n->packet_template_index], &bi0);

	hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

	t0 = (u8 *) & h0->cdp.data;

	/* add TLVs */
	add_tlvs (cm, hw, &t0);

	/* add the cdp packet checksum */
	nbytes_to_checksum = t0 - (u8 *) & h0->cdp;
	checksum = cdp_checksum (&h0->cdp, nbytes_to_checksum);
	h0->cdp.checksum = htons (checksum);

	/* Set the outbound packet length */
	b0 = vlib_get_buffer (vm, bi0);
	b0->current_length = nbytes_to_checksum + sizeof (*h0)
	- sizeof (cdp_hdr_t);

	/* And output the packet on the correct interface */
	f = vlib_get_frame_to_node (vm, hw->output_node_index);
	to_next = vlib_frame_vector_args (f);
	to_next[0] = bi0;
	f->n_vectors = 1;

	vlib_put_frame_to_node (vm, hw->output_node_index, f);
	n->last_sent = vlib_time_now (vm);
	}
	}

	/*
	* send a cdp pkt on an srp interface
	*/
	static void
	send_srp_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
	{
	u32 *to_next;
	srp_and_cdp_header_t *h0;
	vnet_hw_interface_t *hw;
	u32 bi0;
	vlib_buffer_t *b0;
	u8 *t0;
	u16 checksum;
	int nbytes_to_checksum;
	int i;
	vlib_frame_t *f;
	vlib_main_t *vm = cm->vlib_main;
	vnet_main_t *vnm = cm->vnet_main;

	for (i = 0; i < count; i++)
	{
	/*
	* see cdp_periodic_init() to understand what's already painted
	* into the buffer by the packet template mechanism
	*/
	h0 = vlib_packet_template_get_packet
	(vm, &cm->packet_templates[n->packet_template_index], &bi0);

	hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

	t0 = (u8 *) & h0->cdp.data;

	/* add TLVs */
	add_tlvs (cm, hw, &t0);

	/* Add the interface's ethernet source address */
	clib_memcpy (h0->ethernet.src_address, hw->hw_address,
	vec_len (hw->hw_address));

	/* add the cdp packet checksum */
	nbytes_to_checksum = t0 - (u8 *) & h0->cdp;
	checksum = cdp_checksum (&h0->cdp, nbytes_to_checksum);
	h0->cdp.checksum = htons (checksum);

	/* Set the outbound packet length */
	b0 = vlib_get_buffer (vm, bi0);
	b0->current_length = nbytes_to_checksum + sizeof (*h0)
	- sizeof (cdp_hdr_t);

	/* And output the packet on the correct interface */
	f = vlib_get_frame_to_node (vm, hw->output_node_index);
	to_next = vlib_frame_vector_args (f);
	to_next[0] = bi0;
	f->n_vectors = 1;

	vlib_put_frame_to_node (vm, hw->output_node_index, f);
	n->last_sent = vlib_time_now (vm);
	}
	}

	/*
	* Decide which cdp packet template to use
	*/
	static int
	pick_packet_template (cdp_main_t * cm, cdp_neighbor_t * n)
	{
	n->packet_template_index = CDP_PACKET_TEMPLATE_ETHERNET;

	return 0;
	}

	/* Send a cdp neighbor announcement */
	static void
	send_hello (cdp_main_t * cm, cdp_neighbor_t * n, int count)
	{
	if (n->packet_template_index == (u8) ~ 0)
	{
	/* If we don't know how to talk to this peer, don't try again */
	if (pick_packet_template (cm, n))
	{
	n->last_sent = 1e70;
	return;
	}
	}

	switch (n->packet_template_index)
	{
	case CDP_PACKET_TEMPLATE_ETHERNET:
	send_ethernet_hello (cm, n, count);
	break;

	case CDP_PACKET_TEMPLATE_HDLC:
	send_hdlc_hello (cm, n, count);
	break;

	case CDP_PACKET_TEMPLATE_SRP:
	send_srp_hello (cm, n, count);
	break;

	default:
	ASSERT (0);
	}
	n->last_sent = vlib_time_now (cm->vlib_main);
	}

	static void
	delete_neighbor (cdp_main_t * cm, cdp_neighbor_t * n, int want_broadcast)
	{
	hash_unset (cm->neighbor_by_sw_if_index, n->sw_if_index);
	vec_free (n->device_name);
	vec_free (n->version);
	vec_free (n->port_id);
	vec_free (n->platform);
	vec_free (n->last_rx_pkt);
	pool_put (cm->neighbors, n);
	}

	void
	cdp_periodic (vlib_main_t * vm)
	{
	cdp_main_t *cm = &cdp_main;
	cdp_neighbor_t *n;
	f64 now = vlib_time_now (vm);
	vnet_sw_interface_t *sw;
	static u32 *delete_list = 0;
	int i;
	static cdp_neighbor_t **n_list = 0;

	/* INDENT-OFF */
	pool_foreach (n, cm->neighbors,
	({
	vec_add1 (n_list, n);
	}));
	/* INDENT-ON */

	/* Across all cdp neighbors known to the system */
	for (i = 0; i < vec_len (n_list); i++)
	{
	n = n_list[i];

	/* "no cdp run" provisioned on the interface? */
	if (n->disabled == 1)
	continue;

	sw = vnet_get_sw_interface (cm->vnet_main, n->sw_if_index);

	/* Interface shutdown or rx timeout? */
	if (!(sw->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
	\|\| (now > (n->last_heard + (f64) n->ttl_in_seconds)))
	/* add to list of neighbors to delete */
	vec_add1 (delete_list, n - cm->neighbors);
	else if (n->last_sent == 0.0)
	/* First time, send 3 hellos */
	send_hello (cm, n, 3 /* three to begin with */ );
	else if (now > (n->last_sent + (((f64) n->ttl_in_seconds) / 6.0)))
	/* Normal keepalive, send one */
	send_hello (cm, n, 1 /* one as a keepalive */ );
	}

	for (i = 0; i < vec_len (delete_list); i++)
	{
	n = vec_elt_at_index (cm->neighbors, delete_list[i]);
	delete_neighbor (cm, n, 1);
	}
	if (delete_list)
	_vec_len (delete_list) = 0;
	if (n_list)
	_vec_len (n_list) = 0;
	}

	static clib_error_t *
	cdp_periodic_init (vlib_main_t * vm)
	{
	cdp_main_t *cm = &cdp_main;

	/* Create the ethernet cdp hello packet template */
	{
	ethernet_llc_snap_and_cdp_header_t h;

	memset (&h, 0, sizeof (h));

	/* Send to 01:00:0c:cc:cc */
	h.ethernet.dst_address[0] = 0x01;
	/* h.ethernet.dst_address[1] = 0x00; (memset) */
	h.ethernet.dst_address[2] = 0x0C;
	h.ethernet.dst_address[3] = 0xCC;
	h.ethernet.dst_address[4] = 0xCC;
	h.ethernet.dst_address[5] = 0xCC;

	/* leave src address blank (fill in at send time) */

	/* leave length blank (fill in at send time) */

	/* LLC */
	h.llc.dst_sap = h.llc.src_sap = 0xAA; /* SNAP */
	h.llc.control = 0x03; /* UI (no extended control bytes) */

	/* SNAP */
	/* h.snap.oui[0] = 0x00; (memset) */
	/* h.snap.oui[1] = 0x00; (memset) */
	h.snap.oui[2] = 0x0C; /* Cisco = 0x00000C */
	h.snap.protocol = htons (0x2000); /* CDP = 0x2000 */

	/* CDP */
	h.cdp.version = 2;
	h.cdp.ttl = 180;

	vlib_packet_template_init
	(vm, &cm->packet_templates[CDP_PACKET_TEMPLATE_ETHERNET],
	/* data */ &h,
	sizeof (h),
	/* alloc chunk size */ 8,
	"cdp-ethernet");
	}

	#if 0 /* retain for reference */

	/* Create the hdlc cdp hello packet template */
	{
	hdlc_and_cdp_header_t h;

	memset (&h, 0, sizeof (h));

	h.hdlc.address = 0x0f;
	/* h.hdlc.control = 0; (memset) */
	h.hdlc.protocol = htons (0x2000); /* CDP = 0x2000 */

	/* CDP */
	h.cdp.version = 2;
	h.cdp.ttl = 180;

	vlib_packet_template_init
	(vm, &cm->packet_templates[CDP_PACKET_TEMPLATE_HDLC],
	/* data */ &h,
	sizeof (h),
	/* alloc chunk size */ 8,
	"cdp-hdlc");
	}

	/* Create the srp cdp hello packet template */
	{
	srp_and_cdp_header_t h;

	memset (&h, 0, sizeof (h));

	/* Send to 01:00:0c:cc:cc */
	h.ethernet.dst_address[0] = 0x01;
	/* h.ethernet.dst_address[1] = 0x00; (memset) */
	h.ethernet.dst_address[2] = 0x0C;
	h.ethernet.dst_address[3] = 0xCC;
	h.ethernet.dst_address[4] = 0xCC;
	h.ethernet.dst_address[5] = 0xCC;

	/* leave src address blank (fill in at send time) */

	/* The srp header is filled in at xmt */
	h.srp.ttl = 1;
	h.srp.priority = 7;
	h.srp.mode = SRP_MODE_data;
	srp_header_compute_parity (&h.srp);

	/* Inner ring and parity will be set at send time */

	h.ethernet.type = htons (0x2000); /* CDP = 0x2000 */

	/* CDP */
	h.cdp.version = 2;
	h.cdp.ttl = 180;

	vlib_packet_template_init
	(vm, &cm->packet_templates[CDP_PACKET_TEMPLATE_SRP],
	/* data */ &h,
	sizeof (h),
	/* alloc chunk size */ 8,
	"cdp-srp");
	}
	#endif

	return 0;
	}

	VLIB_INIT_FUNCTION (cdp_periodic_init);

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