src/vnet/cdp/cdp_input.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>

 cdp_main_t cdp_main;

 #define DEBUG_TLV_DUMP 0	/* 1=> dump TLV's to stdout while processing them */

 /* Reliable multicast messages we use to keep peers updated */
 mc_serialize_msg_t serialize_cdp_neighbor_msg;
 mc_serialize_msg_t serialize_cdp_keepalive_msg;

 /*
  * ported from an unspecified Cisco cdp implementation.
  * Compute / return in HOST byte order. 0 => good checksum.
  */
 u16
 cdp_checksum (void *p, int count)
 {
   u32 sum;
   u16 i, *data;

   data = p;
   sum = 0;
   while (count > 1)
     {
       sum += ntohs (*data);
       data++;
       count -= 2;
     }

   if (count > 0)
     sum += *(char *) data;

   while (sum >> 16)
     {
       sum = (sum & 0xFFFF) + (sum >> 16);
     }

   i = (i16) sum;
   return (~i);
 }

 /* TLV handler table */
 typedef struct
 {
   char *name;
   u32 tlv_id;
   void *format;
   void *process;
 } tlv_handler_t;

 static tlv_handler_t tlv_handlers[];

 /* Display a generic TLV as a set of hex bytes */
 static u8 *
 format_generic_tlv (u8 * s, va_list * va)
 {
   cdp_tlv_t *t = va_arg (*va, cdp_tlv_t *);
   tlv_handler_t *h = &tlv_handlers[t->t];

   s = format (s, "%s(%d): %U\n", h->name,
 	      t->t, format_hex_bytes, t->v, t->l - sizeof (*t));
   return s;
 }

 /* Ignore / skip a TLV we don't support */
 static cdp_error_t
 process_generic_tlv (cdp_main_t * cm, cdp_neighbor_t * n, cdp_tlv_t * t)
 {
 #if DEBUG_TLV_DUMP > 0
   fformat (stdout, "%U", format_generic_tlv, t);
 #endif

   return CDP_ERROR_NONE;
 }

 /* print a text tlv */
 static u8 *
 format_text_tlv (u8 * s, va_list * va)
 {
   cdp_tlv_t *t = va_arg (*va, cdp_tlv_t *);
   tlv_handler_t *h = &tlv_handlers[t->t];
   int i;

   s = format (s, "%s(%d): ", h->name, t->t);

   for (i = 0; i < (t->l - sizeof (*t)); i++)
     vec_add1 (s, t->v[i]);

   vec_add1 (s, '\n');
   return s;
 }

 #if DEBUG_TLV_DUMP == 0
 /* gcc warning be gone */
 CLIB_UNUSED (static cdp_error_t
 	     process_text_tlv (cdp_main_t * cm, cdp_neighbor_t * n,
 			       cdp_tlv_t * t));
 #endif

 /* process / skip a generic text TLV that we don't support */
 static cdp_error_t
 process_text_tlv (cdp_main_t * cm, cdp_neighbor_t * n, cdp_tlv_t * t)
 {
 #if DEBUG_TLV_DUMP > 0
   fformat (stdout, "%U\n", format_text_tlv, t);
 #endif

   return CDP_ERROR_NONE;
 }

 /* per-TLV format function definitions */
 #define format_unused_tlv format_generic_tlv
 #define format_device_name_tlv format_text_tlv
 #define format_address_tlv format_generic_tlv
 #define format_port_id_tlv format_text_tlv
 #define format_capabilities_tlv format_generic_tlv
 #define format_version_tlv format_text_tlv
 #define format_platform_tlv format_text_tlv
 #define format_ipprefix_tlv format_generic_tlv
 #define format_hello_tlv format_generic_tlv
 #define format_vtp_domain_tlv format_generic_tlv
 #define format_native_vlan_tlv format_generic_tlv
 #define format_duplex_tlv format_generic_tlv
 #define format_appl_vlan_tlv format_generic_tlv
 #define format_trigger_tlv format_generic_tlv
 #define format_power_tlv format_generic_tlv
 #define format_mtu_tlv format_generic_tlv
 #define format_trust_tlv format_generic_tlv
 #define format_cos_tlv format_generic_tlv
 #define format_sysname_tlv format_generic_tlv
 #define format_sysobject_tlv format_generic_tlv
 #define format_mgmt_addr_tlv format_generic_tlv
 #define format_physical_loc_tlv format_generic_tlv
 #define format_mgmt_addr2_tlv format_generic_tlv
 #define format_power_requested_tlv format_generic_tlv
 #define format_power_available_tlv format_generic_tlv
 #define format_port_unidirectional_tlv format_generic_tlv
 #define format_unknown_28_tlv format_generic_tlv
 #define format_energywise_tlv format_generic_tlv
 #define format_unknown_30_tlv format_generic_tlv
 #define format_spare_poe_tlv format_generic_tlv

 /* tlv ID=0 is a mistake */
 static cdp_error_t
 process_unused_tlv (cdp_main_t * cm, cdp_neighbor_t * n, cdp_tlv_t * t)
 {
   return CDP_ERROR_BAD_TLV;
 }

 /* list of text TLV's that we snapshoot */
 #define foreach_text_to_struct_tlv              \
 _(device_name,DEBUG_TLV_DUMP)                   \
 _(version,DEBUG_TLV_DUMP)                       \
 _(platform,DEBUG_TLV_DUMP)                      \
 _(port_id,DEBUG_TLV_DUMP)

 #define _(z,dbg)                                                        \
 static                                                                  \
 cdp_error_t process_##z##_tlv (cdp_main_t *cm, cdp_neighbor_t *n,       \
                                   cdp_tlv_t *t)                         \
 {                                                                       \
     int i;                                                              \
     if (dbg)                                                            \
        fformat(stdout, "%U\n", format_text_tlv, t);                     \
                                                                         \
     if (n->z)                                                           \
         _vec_len(n->z) = 0;                                             \
                                                                         \
     for (i = 0; i < (t->l - sizeof (*t)); i++)                          \
         vec_add1(n->z, t->v[i]);                                        \
                                                                         \
     vec_add1(n->z, 0);                                                  \
                                                                         \
     return CDP_ERROR_NONE;                                              \
 }

 foreach_text_to_struct_tlv
 #undef _
 #define process_address_tlv process_generic_tlv
 #define process_capabilities_tlv process_generic_tlv
 #define process_ipprefix_tlv process_generic_tlv
 #define process_hello_tlv process_generic_tlv
 #define process_vtp_domain_tlv process_generic_tlv
 #define process_native_vlan_tlv process_generic_tlv
 #define process_duplex_tlv process_generic_tlv
 #define process_appl_vlan_tlv process_generic_tlv
 #define process_trigger_tlv process_generic_tlv
 #define process_power_tlv process_generic_tlv
 #define process_mtu_tlv process_generic_tlv
 #define process_trust_tlv process_generic_tlv
 #define process_cos_tlv process_generic_tlv
 #define process_sysname_tlv process_generic_tlv
 #define process_sysobject_tlv process_generic_tlv
 #define process_mgmt_addr_tlv process_generic_tlv
 #define process_physical_loc_tlv process_generic_tlv
 #define process_mgmt_addr2_tlv process_generic_tlv
 #define process_power_requested_tlv process_generic_tlv
 #define process_power_available_tlv process_generic_tlv
 #define process_port_unidirectional_tlv process_generic_tlv
 #define process_unknown_28_tlv process_generic_tlv
 #define process_energywise_tlv process_generic_tlv
 #define process_unknown_30_tlv process_generic_tlv
 #define process_spare_poe_tlv process_generic_tlv
 static tlv_handler_t tlv_handlers[] = {
 #define _(a) {#a, CDP_TLV_##a, format_##a##_tlv, process_##a##_tlv},
   foreach_cdp_tlv_type
 #undef _
 };

 #if DEBUG_TLV_DUMP == 0
 CLIB_UNUSED (static u8 * format_cdp_hdr (u8 * s, va_list * va));
 #endif

 static u8 *
 format_cdp_hdr (u8 * s, va_list * va)
 {
   cdp_hdr_t *h = va_arg (*va, cdp_hdr_t *);

   s = format (s, "version %d, ttl %d(secs), cksum 0x%04x\n",
 	      h->version, h->ttl, h->checksum);
   return s;
 }

 static cdp_error_t
 process_cdp_hdr (cdp_main_t * cm, cdp_neighbor_t * n, cdp_hdr_t * h)
 {
 #if DEBUG_TLV_DUMP > 0
   fformat (stdout, "%U", format_cdp_hdr, h);
 #endif

   if (h->version != 1 && h->version != 2)
     return CDP_ERROR_PROTOCOL_VERSION;

   n->ttl_in_seconds = h->ttl;

   return CDP_ERROR_NONE;
 }

 /* scan a cdp packet; header, then tlv's */
 static int
 cdp_packet_scan (cdp_main_t * cm, cdp_neighbor_t * n)
 {
   u8 *cur = n->last_rx_pkt;
   cdp_hdr_t *h;
   cdp_tlv_t *tlv;
   cdp_error_t e = CDP_ERROR_NONE;
   tlv_handler_t *handler;
   cdp_error_t (*fp) (cdp_main_t *, cdp_neighbor_t *, cdp_tlv_t *);
   u16 computed_checksum;

   computed_checksum = cdp_checksum (cur, vec_len (cur));

   if (computed_checksum)
     return CDP_ERROR_CHECKSUM;

   h = (cdp_hdr_t *) cur;

   e = process_cdp_hdr (cm, n, h);
   if (e)
     return e;

   cur = (u8 *) (h + 1);

   while (cur < n->last_rx_pkt + vec_len (n->last_rx_pkt) - 1)
     {
       tlv = (cdp_tlv_t *) cur;
       tlv->t = ntohs (tlv->t);
       tlv->l = ntohs (tlv->l);
       if (tlv->t >= ARRAY_LEN (tlv_handlers))
 	return CDP_ERROR_BAD_TLV;
       handler = &tlv_handlers[tlv->t];
       fp = handler->process;
       e = (*fp) (cm, n, tlv);
       if (e)
 	return e;
       /* tlv length includes (t, l) */
       cur += tlv->l;
     }

   return CDP_ERROR_NONE;
 }

 /*
  * cdp input routine
  */
 cdp_error_t
 cdp_input (vlib_main_t * vm, vlib_buffer_t * b0, u32 bi0)
 {
   cdp_main_t *cm = &cdp_main;
   cdp_neighbor_t *n;
   uword *p, nbytes;
   cdp_error_t e;
   uword last_packet_signature;

   /* find or create a neighbor pool entry for the (sw) interface
      upon which we received this pkt */
   p = hash_get (cm->neighbor_by_sw_if_index,
 		vnet_buffer (b0)->sw_if_index[VLIB_RX]);

   if (p == 0)
     {
       pool_get (cm->neighbors, n);
       memset (n, 0, sizeof (*n));
       n->sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
       n->packet_template_index = (u8) ~ 0;
       hash_set (cm->neighbor_by_sw_if_index, n->sw_if_index,
 		n - cm->neighbors);
     }
   else
     {
       n = pool_elt_at_index (cm->neighbors, p[0]);
     }

   /*
    * typical clib idiom. Don't repeatedly allocate and free
    * the per-neighbor rx buffer. Reset its apparent length to zero
    * and reuse it.
    */

   if (n->last_rx_pkt)
     _vec_len (n->last_rx_pkt) = 0;

   /* cdp disabled on this interface, we're done */
   if (n->disabled)
     return CDP_ERROR_DISABLED;

   /*
    * Make sure the per-neighbor rx buffer is big enough to hold
    * the data we're about to copy
    */
   vec_validate (n->last_rx_pkt, vlib_buffer_length_in_chain (vm, b0) - 1);

   /*
    * Coalesce / copy e the buffer chain into the per-neighbor
    * rx buffer
    */
   nbytes = vlib_buffer_contents (vm, bi0, n->last_rx_pkt);
   ASSERT (nbytes <= vec_len (n->last_rx_pkt));

   /*
    * Compute Jenkins hash of the new packet, decide if we need to
    * actually parse through the TLV's. CDP packets are all identical,
    * so unless we time out the peer, we don't need to process the packet.
    */
   last_packet_signature =
     hash_memory (n->last_rx_pkt, vec_len (n->last_rx_pkt), 0xd00b);

   if (n->last_packet_signature_valid &&
       n->last_packet_signature == last_packet_signature)
     {
       e = CDP_ERROR_CACHE_HIT;
     }
   else
     {
       /* Actually scan the packet */
       e = cdp_packet_scan (cm, n);
       n->last_packet_signature_valid = 1;
       n->last_packet_signature = last_packet_signature;
     }

   if (e == CDP_ERROR_NONE)
     {
       n->last_heard = vlib_time_now (vm);
     }

   return e;
 }

 /*
  * setup neighbor hash table
  */
 static clib_error_t *
 cdp_init (vlib_main_t * vm)
 {
   clib_error_t *error;
   cdp_main_t *cm = &cdp_main;
   void vnet_cdp_node_reference (void);

   vnet_cdp_node_reference ();

   if ((error = vlib_call_init_function (vm, cdp_periodic_init)))
     return error;

   cm->vlib_main = vm;
   cm->vnet_main = vnet_get_main ();
   cm->neighbor_by_sw_if_index = hash_create (0, sizeof (uword));

   return 0;
 }

 VLIB_INIT_FUNCTION (cdp_init);


 static u8 *
 format_cdp_neighbors (u8 * s, va_list * va)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*va, vlib_main_t *);
   cdp_main_t *cm = va_arg (*va, cdp_main_t *);
   vnet_main_t *vnm = &vnet_main;
   cdp_neighbor_t *n;
   vnet_hw_interface_t *hw;

   s = format (s,
 	      "%=25s %=15s %=25s %=10s\n",
 	      "Our Port", "Peer System", "Peer Port", "Last Heard");

   /* *INDENT-OFF* */
   pool_foreach (n, cm->neighbors,
   ({
     hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

     if (n->disabled == 0)
       s = format (s, "%=25s %=15s %=25s %=10.1f\n",
                   hw->name, n->device_name, n->port_id,
                   n->last_heard);
   }));
   /* *INDENT-ON* */
   return s;
 }


 static clib_error_t *
 show_cdp (vlib_main_t * vm,
 	  unformat_input_t * input, vlib_cli_command_t * cmd)
 {
   cdp_main_t *cm = &cdp_main;

   vlib_cli_output (vm, "%U\n", format_cdp_neighbors, vm, cm);

   return 0;
 }

 /* *INDENT-OFF* */
 VLIB_CLI_COMMAND (show_cdp_command, static) = {
   .path = "show cdp",
   .short_help = "Show cdp command",
   .function = show_cdp,
 };
 /* *INDENT-ON* */


 /*
  * packet trace format function, very similar to
  * cdp_packet_scan except that we call the per TLV format
  * functions instead of the per TLV processing functions
  */
 u8 *
 cdp_input_format_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 *);
   cdp_input_trace_t *t = va_arg (*args, cdp_input_trace_t *);
   u8 *cur;
   cdp_hdr_t *h;
   cdp_tlv_t *tlv;
   tlv_handler_t *handler;
   u8 *(*fp) (cdp_tlv_t *);

   cur = t->data;

   h = (cdp_hdr_t *) cur;
   s = format (s, "%U", format_cdp_hdr, h);

   cur = (u8 *) (h + 1);

   while (cur < t->data + t->len)
     {
       tlv = (cdp_tlv_t *) cur;
       tlv->t = ntohs (tlv->t);
       tlv->l = ntohs (tlv->l);
       if (tlv->t >= ARRAY_LEN (tlv_handlers))
 	{
 	  s = format (s, "BAD_TLV\n");
 	  break;
 	}
       handler = &tlv_handlers[tlv->t];
       fp = handler->format;
       s = format (s, "  %U", fp, tlv);
       /* tlv length includes (t, l) */
       cur += tlv->l;
     }

   return s;
 }

 /*
  * 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>

	cdp_main_t cdp_main;

	#define DEBUG_TLV_DUMP 0 /* 1=> dump TLV's to stdout while processing them */

	/* Reliable multicast messages we use to keep peers updated */
	mc_serialize_msg_t serialize_cdp_neighbor_msg;
	mc_serialize_msg_t serialize_cdp_keepalive_msg;

	/*
	* ported from an unspecified Cisco cdp implementation.
	* Compute / return in HOST byte order. 0 => good checksum.
	*/
	u16
	cdp_checksum (void *p, int count)
	{
	u32 sum;
	u16 i, *data;

	data = p;
	sum = 0;
	while (count > 1)
	{
	sum += ntohs (*data);
	data++;
	count -= 2;
	}

	if (count > 0)
	sum += (char ) data;

	while (sum >> 16)
	{
	sum = (sum & 0xFFFF) + (sum >> 16);
	}

	i = (i16) sum;
	return (~i);
	}

	/* TLV handler table */
	typedef struct
	{
	char *name;
	u32 tlv_id;
	void *format;
	void *process;
	} tlv_handler_t;

	static tlv_handler_t tlv_handlers[];

	/* Display a generic TLV as a set of hex bytes */
	static u8 *
	format_generic_tlv (u8 * s, va_list * va)
	{
	cdp_tlv_t t = va_arg (va, cdp_tlv_t *);
	tlv_handler_t *h = &tlv_handlers[t->t];

	s = format (s, "%s(%d): %U\n", h->name,
	t->t, format_hex_bytes, t->v, t->l - sizeof (*t));
	return s;
	}

	/* Ignore / skip a TLV we don't support */
	static cdp_error_t
	process_generic_tlv (cdp_main_t * cm, cdp_neighbor_t * n, cdp_tlv_t * t)
	{
	#if DEBUG_TLV_DUMP > 0
	fformat (stdout, "%U", format_generic_tlv, t);
	#endif

	return CDP_ERROR_NONE;
	}

	/* print a text tlv */
	static u8 *
	format_text_tlv (u8 * s, va_list * va)
	{
	cdp_tlv_t t = va_arg (va, cdp_tlv_t *);
	tlv_handler_t *h = &tlv_handlers[t->t];
	int i;

	s = format (s, "%s(%d): ", h->name, t->t);

	for (i = 0; i < (t->l - sizeof (*t)); i++)
	vec_add1 (s, t->v[i]);

	vec_add1 (s, '\n');
	return s;
	}

	#if DEBUG_TLV_DUMP == 0
	/* gcc warning be gone */
	CLIB_UNUSED (static cdp_error_t
	process_text_tlv (cdp_main_t * cm, cdp_neighbor_t * n,
	cdp_tlv_t * t));
	#endif

	/* process / skip a generic text TLV that we don't support */
	static cdp_error_t
	process_text_tlv (cdp_main_t * cm, cdp_neighbor_t * n, cdp_tlv_t * t)
	{
	#if DEBUG_TLV_DUMP > 0
	fformat (stdout, "%U\n", format_text_tlv, t);
	#endif

	return CDP_ERROR_NONE;
	}

	/* per-TLV format function definitions */
	#define format_unused_tlv format_generic_tlv
	#define format_device_name_tlv format_text_tlv
	#define format_address_tlv format_generic_tlv
	#define format_port_id_tlv format_text_tlv
	#define format_capabilities_tlv format_generic_tlv
	#define format_version_tlv format_text_tlv
	#define format_platform_tlv format_text_tlv
	#define format_ipprefix_tlv format_generic_tlv
	#define format_hello_tlv format_generic_tlv
	#define format_vtp_domain_tlv format_generic_tlv
	#define format_native_vlan_tlv format_generic_tlv
	#define format_duplex_tlv format_generic_tlv
	#define format_appl_vlan_tlv format_generic_tlv
	#define format_trigger_tlv format_generic_tlv
	#define format_power_tlv format_generic_tlv
	#define format_mtu_tlv format_generic_tlv
	#define format_trust_tlv format_generic_tlv
	#define format_cos_tlv format_generic_tlv
	#define format_sysname_tlv format_generic_tlv
	#define format_sysobject_tlv format_generic_tlv
	#define format_mgmt_addr_tlv format_generic_tlv
	#define format_physical_loc_tlv format_generic_tlv
	#define format_mgmt_addr2_tlv format_generic_tlv
	#define format_power_requested_tlv format_generic_tlv
	#define format_power_available_tlv format_generic_tlv
	#define format_port_unidirectional_tlv format_generic_tlv
	#define format_unknown_28_tlv format_generic_tlv
	#define format_energywise_tlv format_generic_tlv
	#define format_unknown_30_tlv format_generic_tlv
	#define format_spare_poe_tlv format_generic_tlv

	/* tlv ID=0 is a mistake */
	static cdp_error_t
	process_unused_tlv (cdp_main_t * cm, cdp_neighbor_t * n, cdp_tlv_t * t)
	{
	return CDP_ERROR_BAD_TLV;
	}

	/* list of text TLV's that we snapshoot */
	#define foreach_text_to_struct_tlv \
	_(device_name,DEBUG_TLV_DUMP) \
	_(version,DEBUG_TLV_DUMP) \
	_(platform,DEBUG_TLV_DUMP) \
	_(port_id,DEBUG_TLV_DUMP)

	#define _(z,dbg) \
	static \
	cdp_error_t process_##z##_tlv (cdp_main_t cm, cdp_neighbor_t n, \
	cdp_tlv_t *t) \
	{ \
	int i; \
	if (dbg) \
	fformat(stdout, "%U\n", format_text_tlv, t); \
	\
	if (n->z) \
	_vec_len(n->z) = 0; \
	\
	for (i = 0; i < (t->l - sizeof (*t)); i++) \
	vec_add1(n->z, t->v[i]); \
	\
	vec_add1(n->z, 0); \
	\
	return CDP_ERROR_NONE; \
	}

	foreach_text_to_struct_tlv
	#undef _
	#define process_address_tlv process_generic_tlv
	#define process_capabilities_tlv process_generic_tlv
	#define process_ipprefix_tlv process_generic_tlv
	#define process_hello_tlv process_generic_tlv
	#define process_vtp_domain_tlv process_generic_tlv
	#define process_native_vlan_tlv process_generic_tlv
	#define process_duplex_tlv process_generic_tlv
	#define process_appl_vlan_tlv process_generic_tlv
	#define process_trigger_tlv process_generic_tlv
	#define process_power_tlv process_generic_tlv
	#define process_mtu_tlv process_generic_tlv
	#define process_trust_tlv process_generic_tlv
	#define process_cos_tlv process_generic_tlv
	#define process_sysname_tlv process_generic_tlv
	#define process_sysobject_tlv process_generic_tlv
	#define process_mgmt_addr_tlv process_generic_tlv
	#define process_physical_loc_tlv process_generic_tlv
	#define process_mgmt_addr2_tlv process_generic_tlv
	#define process_power_requested_tlv process_generic_tlv
	#define process_power_available_tlv process_generic_tlv
	#define process_port_unidirectional_tlv process_generic_tlv
	#define process_unknown_28_tlv process_generic_tlv
	#define process_energywise_tlv process_generic_tlv
	#define process_unknown_30_tlv process_generic_tlv
	#define process_spare_poe_tlv process_generic_tlv
	static tlv_handler_t tlv_handlers[] = {
	#define _(a) {#a, CDP_TLV_##a, format_##a##_tlv, process_##a##_tlv},
	foreach_cdp_tlv_type
	#undef _
	};

	#if DEBUG_TLV_DUMP == 0
	CLIB_UNUSED (static u8 * format_cdp_hdr (u8 * s, va_list * va));
	#endif

	static u8 *
	format_cdp_hdr (u8 * s, va_list * va)
	{
	cdp_hdr_t h = va_arg (va, cdp_hdr_t *);

	s = format (s, "version %d, ttl %d(secs), cksum 0x%04x\n",
	h->version, h->ttl, h->checksum);
	return s;
	}

	static cdp_error_t
	process_cdp_hdr (cdp_main_t * cm, cdp_neighbor_t * n, cdp_hdr_t * h)
	{
	#if DEBUG_TLV_DUMP > 0
	fformat (stdout, "%U", format_cdp_hdr, h);
	#endif

	if (h->version != 1 && h->version != 2)
	return CDP_ERROR_PROTOCOL_VERSION;

	n->ttl_in_seconds = h->ttl;

	return CDP_ERROR_NONE;
	}

	/* scan a cdp packet; header, then tlv's */
	static int
	cdp_packet_scan (cdp_main_t * cm, cdp_neighbor_t * n)
	{
	u8 *cur = n->last_rx_pkt;
	cdp_hdr_t *h;
	cdp_tlv_t *tlv;
	cdp_error_t e = CDP_ERROR_NONE;
	tlv_handler_t *handler;
	cdp_error_t (fp) (cdp_main_t , cdp_neighbor_t , cdp_tlv_t );
	u16 computed_checksum;

	computed_checksum = cdp_checksum (cur, vec_len (cur));

	if (computed_checksum)
	return CDP_ERROR_CHECKSUM;

	h = (cdp_hdr_t *) cur;

	e = process_cdp_hdr (cm, n, h);
	if (e)
	return e;

	cur = (u8 *) (h + 1);

	while (cur < n->last_rx_pkt + vec_len (n->last_rx_pkt) - 1)
	{
	tlv = (cdp_tlv_t *) cur;
	tlv->t = ntohs (tlv->t);
	tlv->l = ntohs (tlv->l);
	if (tlv->t >= ARRAY_LEN (tlv_handlers))
	return CDP_ERROR_BAD_TLV;
	handler = &tlv_handlers[tlv->t];
	fp = handler->process;
	e = (*fp) (cm, n, tlv);
	if (e)
	return e;
	/* tlv length includes (t, l) */
	cur += tlv->l;
	}

	return CDP_ERROR_NONE;
	}

	/*
	* cdp input routine
	*/
	cdp_error_t
	cdp_input (vlib_main_t * vm, vlib_buffer_t * b0, u32 bi0)
	{
	cdp_main_t *cm = &cdp_main;
	cdp_neighbor_t *n;
	uword *p, nbytes;
	cdp_error_t e;
	uword last_packet_signature;

	/* find or create a neighbor pool entry for the (sw) interface
	upon which we received this pkt */
	p = hash_get (cm->neighbor_by_sw_if_index,
	vnet_buffer (b0)->sw_if_index[VLIB_RX]);

	if (p == 0)
	{
	pool_get (cm->neighbors, n);
	memset (n, 0, sizeof (*n));
	n->sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	n->packet_template_index = (u8) ~ 0;
	hash_set (cm->neighbor_by_sw_if_index, n->sw_if_index,
	n - cm->neighbors);
	}
	else
	{
	n = pool_elt_at_index (cm->neighbors, p[0]);
	}

	/*
	* typical clib idiom. Don't repeatedly allocate and free
	* the per-neighbor rx buffer. Reset its apparent length to zero
	* and reuse it.
	*/

	if (n->last_rx_pkt)
	_vec_len (n->last_rx_pkt) = 0;

	/* cdp disabled on this interface, we're done */
	if (n->disabled)
	return CDP_ERROR_DISABLED;

	/*
	* Make sure the per-neighbor rx buffer is big enough to hold
	* the data we're about to copy
	*/
	vec_validate (n->last_rx_pkt, vlib_buffer_length_in_chain (vm, b0) - 1);

	/*
	* Coalesce / copy e the buffer chain into the per-neighbor
	* rx buffer
	*/
	nbytes = vlib_buffer_contents (vm, bi0, n->last_rx_pkt);
	ASSERT (nbytes <= vec_len (n->last_rx_pkt));

	/*
	* Compute Jenkins hash of the new packet, decide if we need to
	* actually parse through the TLV's. CDP packets are all identical,
	* so unless we time out the peer, we don't need to process the packet.
	*/
	last_packet_signature =
	hash_memory (n->last_rx_pkt, vec_len (n->last_rx_pkt), 0xd00b);

	if (n->last_packet_signature_valid &&
	n->last_packet_signature == last_packet_signature)
	{
	e = CDP_ERROR_CACHE_HIT;
	}
	else
	{
	/* Actually scan the packet */
	e = cdp_packet_scan (cm, n);
	n->last_packet_signature_valid = 1;
	n->last_packet_signature = last_packet_signature;
	}

	if (e == CDP_ERROR_NONE)
	{
	n->last_heard = vlib_time_now (vm);
	}

	return e;
	}

	/*
	* setup neighbor hash table
	*/
	static clib_error_t *
	cdp_init (vlib_main_t * vm)
	{
	clib_error_t *error;
	cdp_main_t *cm = &cdp_main;
	void vnet_cdp_node_reference (void);

	vnet_cdp_node_reference ();

	if ((error = vlib_call_init_function (vm, cdp_periodic_init)))
	return error;

	cm->vlib_main = vm;
	cm->vnet_main = vnet_get_main ();
	cm->neighbor_by_sw_if_index = hash_create (0, sizeof (uword));

	return 0;
	}

	VLIB_INIT_FUNCTION (cdp_init);


	static u8 *
	format_cdp_neighbors (u8 * s, va_list * va)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (va, vlib_main_t );
	cdp_main_t cm = va_arg (va, cdp_main_t *);
	vnet_main_t *vnm = &vnet_main;
	cdp_neighbor_t *n;
	vnet_hw_interface_t *hw;

	s = format (s,
	"%=25s %=15s %=25s %=10s\n",
	"Our Port", "Peer System", "Peer Port", "Last Heard");

	/* INDENT-OFF */
	pool_foreach (n, cm->neighbors,
	({
	hw = vnet_get_sup_hw_interface (vnm, n->sw_if_index);

	if (n->disabled == 0)
	s = format (s, "%=25s %=15s %=25s %=10.1f\n",
	hw->name, n->device_name, n->port_id,
	n->last_heard);
	}));
	/* INDENT-ON */
	return s;
	}


	static clib_error_t *
	show_cdp (vlib_main_t * vm,
	unformat_input_t * input, vlib_cli_command_t * cmd)
	{
	cdp_main_t *cm = &cdp_main;

	vlib_cli_output (vm, "%U\n", format_cdp_neighbors, vm, cm);

	return 0;
	}

	/* INDENT-OFF */
	VLIB_CLI_COMMAND (show_cdp_command, static) = {
	.path = "show cdp",
	.short_help = "Show cdp command",
	.function = show_cdp,
	};
	/* INDENT-ON */


	/*
	* packet trace format function, very similar to
	* cdp_packet_scan except that we call the per TLV format
	* functions instead of the per TLV processing functions
	*/
	u8 *
	cdp_input_format_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 );
	cdp_input_trace_t t = va_arg (args, cdp_input_trace_t *);
	u8 *cur;
	cdp_hdr_t *h;
	cdp_tlv_t *tlv;
	tlv_handler_t *handler;
	u8 (fp) (cdp_tlv_t *);

	cur = t->data;

	h = (cdp_hdr_t *) cur;
	s = format (s, "%U", format_cdp_hdr, h);

	cur = (u8 *) (h + 1);

	while (cur < t->data + t->len)
	{
	tlv = (cdp_tlv_t *) cur;
	tlv->t = ntohs (tlv->t);
	tlv->l = ntohs (tlv->l);
	if (tlv->t >= ARRAY_LEN (tlv_handlers))
	{
	s = format (s, "BAD_TLV\n");
	break;
	}
	handler = &tlv_handlers[tlv->t];
	fp = handler->format;
	s = format (s, " %U", fp, tlv);
	/* tlv length includes (t, l) */
	cur += tlv->l;
	}

	return s;
	}

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