/* BGP attributes management routines.
   Copyright (C) 1996, 97, 98, 1999 Kunihiro Ishiguro

This file is part of GNU Zebra.

GNU Zebra is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

GNU Zebra is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Zebra; see the file COPYING.  If not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#include <zebra.h>

#include "linklist.h"
#include "prefix.h"
#include "memory.h"
#include "vector.h"
#include "vty.h"
#include "stream.h"
#include "log.h"
#include "hash.h"

#include "bgpd/bgpd.h"
#include "bgpd/bgp_attr.h"
#include "bgpd/bgp_route.h"
#include "bgpd/bgp_aspath.h"
#include "bgpd/bgp_community.h"
#include "bgpd/bgp_debug.h"
#include "bgpd/bgp_packet.h"
#include "bgpd/bgp_ecommunity.h"

/* Attribute strings for logging. */
struct message attr_str [] = 
{
  { BGP_ATTR_ORIGIN,           "ORIGIN" }, 
  { BGP_ATTR_AS_PATH,          "AS_PATH" }, 
  { BGP_ATTR_NEXT_HOP,         "NEXT_HOP" }, 
  { BGP_ATTR_MULTI_EXIT_DISC,  "MULTI_EXIT_DISC" }, 
  { BGP_ATTR_LOCAL_PREF,       "LOCAL_PREF" }, 
  { BGP_ATTR_ATOMIC_AGGREGATE, "ATOMIC_AGGREGATE" }, 
  { BGP_ATTR_AGGREGATOR,       "AGGREGATOR" }, 
  { BGP_ATTR_COMMUNITIES,      "COMMUNITY" }, 
  { BGP_ATTR_ORIGINATOR_ID,    "ORIGINATOR_ID" },
  { BGP_ATTR_CLUSTER_LIST,     "CLUSTERLIST" }, 
  { BGP_ATTR_DPA,              "DPA" },
  { BGP_ATTR_ADVERTISER,       "ADVERTISER"} ,
  { BGP_ATTR_RCID_PATH,        "RCID_PATH" },
  { BGP_ATTR_MP_REACH_NLRI,    "MP_REACH_NLRI" },
  { BGP_ATTR_MP_UNREACH_NLRI,  "MP_UNREACH_NLRI" },
  { BGP_ATTR_AS4_PATH,         "AS4_PATH" }, 
  { BGP_ATTR_AS4_AGGREGATOR,   "AS4_AGGREGATOR" }, 
  { 0, NULL }
};

struct hash *cluster_hash;

static void *
cluster_hash_alloc (struct cluster_list *val)
{
  struct cluster_list *cluster;

  cluster = XMALLOC (MTYPE_CLUSTER, sizeof (struct cluster_list));
  cluster->length = val->length;

  if (cluster->length)
    {
      cluster->list = XMALLOC (MTYPE_CLUSTER_VAL, val->length);
      memcpy (cluster->list, val->list, val->length);
    }
  else
    cluster->list = NULL;

  cluster->refcnt = 0;

  return cluster;
}

/* Cluster list related functions. */
static struct cluster_list *
cluster_parse (struct in_addr * pnt, int length)
{
  struct cluster_list tmp;
  struct cluster_list *cluster;

  tmp.length = length;
  tmp.list = pnt;

  cluster = hash_get (cluster_hash, &tmp, cluster_hash_alloc);
  cluster->refcnt++;
  return cluster;
}

int
cluster_loop_check (struct cluster_list *cluster, struct in_addr originator)
{
  int i;
    
  for (i = 0; i < cluster->length / 4; i++)
    if (cluster->list[i].s_addr == originator.s_addr)
      return 1;
  return 0;
}

static unsigned int
cluster_hash_key_make (struct cluster_list *cluster)
{
  unsigned int key = 0;
  int length;
  caddr_t pnt;

  length = cluster->length;
  pnt = (caddr_t) cluster->list;
  
  while (length)
    key += pnt[--length];

  return key;
}

static int
cluster_hash_cmp (struct cluster_list *cluster1, struct cluster_list *cluster2)
{
  if (cluster1->length == cluster2->length &&
      memcmp (cluster1->list, cluster2->list, cluster1->length) == 0)
    return 1;
  return 0;
}

static void
cluster_free (struct cluster_list *cluster)
{
  if (cluster->list)
    XFREE (MTYPE_CLUSTER_VAL, cluster->list);
  XFREE (MTYPE_CLUSTER, cluster);
}

static struct cluster_list *
cluster_dup (struct cluster_list *cluster)
{
  struct cluster_list *new;

  new = XMALLOC (MTYPE_CLUSTER, sizeof (struct cluster_list));
  memset (new, 0, sizeof (struct cluster_list));
  new->length = cluster->length;

  if (cluster->length)
    {
      new->list = XMALLOC (MTYPE_CLUSTER_VAL, cluster->length);
      memcpy (new->list, cluster->list, cluster->length);
    }
  else
    new->list = NULL;
  
  return new;
}

static struct cluster_list *
cluster_intern (struct cluster_list *cluster)
{
  struct cluster_list *find;

  find = hash_get (cluster_hash, cluster, cluster_hash_alloc);
  find->refcnt++;

  return find;
}

void
cluster_unintern (struct cluster_list *cluster)
{
  struct cluster_list *ret;

  if (cluster->refcnt)
    cluster->refcnt--;

  if (cluster->refcnt == 0)
    {
      ret = hash_release (cluster_hash, cluster);
      cluster_free (cluster);
    }
}

static void
cluster_init (void)
{
  cluster_hash = hash_create (cluster_hash_key_make, cluster_hash_cmp);
}

/* Unknown transit attribute. */
struct hash *transit_hash;

static void
transit_free (struct transit *transit)
{
  if (transit->val)
    XFREE (MTYPE_TRANSIT_VAL, transit->val);
  XFREE (MTYPE_TRANSIT, transit);
}

static void *
transit_hash_alloc (struct transit *transit)
{
  /* Transit structure is already allocated.  */
  return transit;
}

static struct transit *
transit_intern (struct transit *transit)
{
  struct transit *find;

  find = hash_get (transit_hash, transit, transit_hash_alloc);
  if (find != transit)
    transit_free (transit);
  find->refcnt++;

  return find;
}

void
transit_unintern (struct transit *transit)
{
  struct transit *ret;

  if (transit->refcnt)
    transit->refcnt--;

  if (transit->refcnt == 0)
    {
      ret = hash_release (transit_hash, transit);
      transit_free (transit);
    }
}

static unsigned int
transit_hash_key_make (struct transit *transit)
{
  unsigned int key = 0;
  int length;
  caddr_t pnt;

  length = transit->length;
  pnt = (caddr_t) transit->val;
  
  while (length)
    key += pnt[--length];

  return key;
}

static int
transit_hash_cmp (struct transit *transit1, struct transit *transit2)
{
  if (transit1->length == transit2->length &&
      memcmp (transit1->val, transit2->val, transit1->length) == 0)
    return 1;
  return 0;
}

static void
transit_init ()
{
  transit_hash = hash_create (transit_hash_key_make, transit_hash_cmp);
}

/* Attribute hash routines. */

struct hash *attrhash;

unsigned long int
attr_count (void)
{
  return attrhash->count;
}

unsigned long int
attr_unknown_count (void)
{
  return transit_hash->count;
}

unsigned int
attrhash_key_make (struct attr *attr)
{
  unsigned int key = 0;

  key += attr->origin;
  key += attr->nexthop.s_addr;
  key += attr->med;
  key += attr->local_pref;
  key += attr->aggregator_as;
  key += attr->aggregator_addr.s_addr;
  key += attr->weight;

  key += attr->mp_nexthop_global_in.s_addr;
  if (attr->aspath)
    key += aspath_key_make (attr->aspath);
  if (attr->community)
    key += community_hash_make (attr->community);
  if (attr->ecommunity)
    key += ecommunity_hash_make (attr->ecommunity);
  if (attr->cluster)
    key += cluster_hash_key_make (attr->cluster);
  if (attr->transit)
    key += transit_hash_key_make (attr->transit);

#ifdef HAVE_IPV6
 {
   int i;
   
   key += attr->mp_nexthop_len;
   for (i = 0; i < 16; i++)
     key += attr->mp_nexthop_global.s6_addr[i];
   for (i = 0; i < 16; i++)
     key += attr->mp_nexthop_local.s6_addr[i];
 }
#endif /* HAVE_IPV6 */

  return key;
}

int
attrhash_cmp (struct attr *attr1, struct attr *attr2)
{
  if (attr1->flag == attr2->flag
      && attr1->origin == attr2->origin
      && attr1->nexthop.s_addr == attr2->nexthop.s_addr
      && attr1->med == attr2->med
      && attr1->local_pref == attr2->local_pref
      && attr1->aggregator_as == attr2->aggregator_as
      && attr1->aggregator_addr.s_addr == attr2->aggregator_addr.s_addr
      && attr1->weight == attr2->weight
#ifdef HAVE_IPV6
      && attr1->mp_nexthop_len == attr2->mp_nexthop_len
      && IPV6_ADDR_SAME (&attr1->mp_nexthop_global, &attr2->mp_nexthop_global)
      && IPV6_ADDR_SAME (&attr1->mp_nexthop_local, &attr2->mp_nexthop_local)
#endif /* HAVE_IPV6 */
      && IPV4_ADDR_SAME (&attr1->mp_nexthop_global_in, &attr2->mp_nexthop_global_in)
      && attr1->aspath == attr2->aspath
      && attr1->community == attr2->community
      && attr1->ecommunity == attr2->ecommunity
      && attr1->cluster == attr2->cluster
      && attr1->transit == attr2->transit)
    return 1;
  else
    return 0;
}

static void
attrhash_init ()
{
  attrhash = hash_create (attrhash_key_make, attrhash_cmp);
}

static void
attr_show_all_iterator (struct hash_backet *backet, struct vty *vty)
{
  struct attr *attr = backet->data;

  vty_out (vty, "attr[%ld] nexthop %s%s", attr->refcnt, 
	   inet_ntoa (attr->nexthop), VTY_NEWLINE);
}

void
attr_show_all (struct vty *vty)
{
  hash_iterate (attrhash, 
		(void (*)(struct hash_backet *, void *))
		attr_show_all_iterator,
		vty);
}

static void *
bgp_attr_hash_alloc (struct attr *val)
{
  struct attr *attr;

  attr = XMALLOC (MTYPE_ATTR, sizeof (struct attr));
  *attr = *val;
  attr->refcnt = 0;
  return attr;
}

/* Internet argument attribute. */
struct attr *
bgp_attr_intern (struct attr *attr)
{
  struct attr *find;

  /* Intern referenced strucutre. */
  if (attr->aspath)
    {
      if (! attr->aspath->refcnt)
	attr->aspath = aspath_intern (attr->aspath);
      else
	attr->aspath->refcnt++;
    }
  if (attr->community)
    {
      if (! attr->community->refcnt)
	attr->community = community_intern (attr->community);
      else
	attr->community->refcnt++;
    }
  if (attr->ecommunity)
    {
      if (! attr->ecommunity->refcnt)
	attr->ecommunity = ecommunity_intern (attr->ecommunity);
      else
	attr->ecommunity->refcnt++;
    }
  if (attr->cluster)
    {
      if (! attr->cluster->refcnt)
	attr->cluster = cluster_intern (attr->cluster);
      else
	attr->cluster->refcnt++;
    }
  if (attr->transit)
    {
      if (! attr->transit->refcnt)
	attr->transit = transit_intern (attr->transit);
      else
	attr->transit->refcnt++;
    }

  find = (struct attr *) hash_get (attrhash, attr, bgp_attr_hash_alloc);
  find->refcnt++;

  return find;
}

/* Make network statement's attribute. */
struct attr *
bgp_attr_default_set (struct attr *attr, u_char origin)
{
  memset (attr, 0, sizeof (struct attr));

  attr->origin = origin;
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_ORIGIN);
  attr->aspath = aspath_empty ();
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_AS_PATH);
  attr->weight = 32768;
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_NEXT_HOP);
#ifdef HAVE_IPV6
  attr->mp_nexthop_len = 16;
#endif
  return attr;
}

/* Make network statement's attribute. */
struct attr *
bgp_attr_default_intern (u_char origin)
{
  struct attr attr;
  struct attr *new;

  memset (&attr, 0, sizeof (struct attr));

  attr.origin = origin;
  attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_ORIGIN);
  attr.aspath = aspath_empty ();
  attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_AS_PATH);
  attr.weight = 32768;
  attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_NEXT_HOP);
#ifdef HAVE_IPV6
  attr.mp_nexthop_len = 16;
#endif

  new = bgp_attr_intern (&attr);
  aspath_unintern (new->aspath);
  return new;
}

struct attr *
bgp_attr_aggregate_intern (struct bgp *bgp, u_char origin,
			   struct aspath *aspath,
			   struct community *community, int as_set)
{
  struct attr attr;
  struct attr *new;

  memset (&attr, 0, sizeof (struct attr));

  /* Origin attribute. */
  attr.origin = origin;
  attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_ORIGIN);

  /* AS path attribute. */
  if (aspath)
    attr.aspath = aspath_intern (aspath);
  else
    attr.aspath = aspath_empty ();
  attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_AS_PATH);

  /* Next hop attribute.  */
  attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_NEXT_HOP);

  if (community)
    {
      attr.community = community;
      attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES);
    }

  attr.weight = 32768;
#ifdef HAVE_IPV6
  attr.mp_nexthop_len = 16;
#endif
  if (! as_set)
    attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_ATOMIC_AGGREGATE);
  attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_AGGREGATOR);
  if (CHECK_FLAG (bgp->config, BGP_CONFIG_CONFEDERATION))
    attr.aggregator_as = bgp->confed_id;
  else
    attr.aggregator_as = bgp->as;
  attr.aggregator_addr = bgp->router_id;

  new = bgp_attr_intern (&attr);
  aspath_unintern (new->aspath);
  return new;
}

/* Free bgp attribute and aspath. */
void
bgp_attr_unintern (struct attr *attr)
{
  struct attr *ret;
  struct aspath *aspath;
  struct community *community;
  struct ecommunity *ecommunity;
  struct cluster_list *cluster;
  struct transit *transit;

  /* Decrement attribute reference. */
  attr->refcnt--;
  aspath = attr->aspath;
  community = attr->community;
  ecommunity = attr->ecommunity;
  cluster = attr->cluster;
  transit = attr->transit;

  /* If reference becomes zero then free attribute object. */
  if (attr->refcnt == 0)
    {    
      ret = hash_release (attrhash, attr);
      assert (ret != NULL);
      XFREE (MTYPE_ATTR, attr);
    }

  /* aspath refcount shoud be decrement. */
  if (aspath)
    aspath_unintern (aspath);
  if (community)
    community_unintern (community);
  if (ecommunity)
    ecommunity_unintern (ecommunity);
  if (cluster)
    cluster_unintern (cluster);
  if (transit)
    transit_unintern (transit);
}

void
bgp_attr_flush (struct attr *attr)
{
  if (attr->aspath && ! attr->aspath->refcnt)
    aspath_free (attr->aspath);
  if (attr->community && ! attr->community->refcnt)
    community_free (attr->community);
  if (attr->ecommunity && ! attr->ecommunity->refcnt)
    ecommunity_free (attr->ecommunity);
  if (attr->cluster && ! attr->cluster->refcnt)
    cluster_free (attr->cluster);
  if (attr->transit && ! attr->transit->refcnt)
    transit_free (attr->transit);
}

/* Get origin attribute of the update message. */
static int
bgp_attr_origin (struct peer *peer, bgp_size_t length, 
		 struct attr *attr, u_char flag, u_char *startp)
{
  bgp_size_t total;

  /* total is entire attribute length include Attribute Flags (1),
     Attribute Type code (1) and Attribute length (1 or 2).  */
  total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);

  /* If any recognized attribute has Attribute Flags that conflict
     with the Attribute Type Code, then the Error Subcode is set to
     Attribute Flags Error.  The Data field contains the erroneous
     attribute (type, length and value). */
  if (flag != BGP_ATTR_FLAG_TRANS)
    {
      zlog (peer->log, LOG_ERR, 
	    "Origin attribute flag isn't transitive %d", flag);
      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_ATTR_FLAG_ERR,
				 startp, total);
      return -1;
    }

  /* If any recognized attribute has Attribute Length that conflicts
     with the expected length (based on the attribute type code), then
     the Error Subcode is set to Attribute Length Error.  The Data
     field contains the erroneous attribute (type, length and
     value). */
  if (length != 1)
    {
      zlog (peer->log, LOG_ERR, "Origin attribute length is not one %d",
	    length);
      bgp_notify_send_with_data (peer, BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
				 startp, total);
      return -1;
    }

  /* Fetch origin attribute. */
  attr->origin = stream_getc (BGP_INPUT (peer));

  /* If the ORIGIN attribute has an undefined value, then the Error
     Subcode is set to Invalid Origin Attribute.  The Data field
     contains the unrecognized attribute (type, length and value). */
  if ((attr->origin != BGP_ORIGIN_IGP)
      && (attr->origin != BGP_ORIGIN_EGP)
      && (attr->origin != BGP_ORIGIN_INCOMPLETE))
    {
      zlog (peer->log, LOG_ERR, "Origin attribute value is invalid %d",
	      attr->origin);

      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_INVAL_ORIGIN,
				 startp, total);
      return -1;
    }

  /* Set oring attribute flag. */
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_ORIGIN);

  return 0;
}

/* Parse AS path information.  This function is wrapper of
   aspath_parse. */
static int
bgp_attr_aspath (struct peer *peer, bgp_size_t length, 
		 struct attr *attr, u_char flag, u_char *startp)
{
  bgp_size_t total;

  total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);

  /* Flag check. */
  if (CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL)
      || ! CHECK_FLAG (flag, BGP_ATTR_FLAG_TRANS))
    {
      zlog (peer->log, LOG_ERR, 
	    "Origin attribute flag isn't transitive %d", flag);
      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_ATTR_FLAG_ERR,
				 startp, total);
      return -1;
    }

  /*
   * peer with AS4 => will get 4Byte ASnums
   * otherwise, will get 16 Bit
   */
  if ( CHECK_FLAG (peer->cap, PEER_CAP_AS4_RCV ) )
    attr->aspath = aspath_parse (peer->ibuf, length, 1);
  else
    attr->aspath = aspath_parse (peer->ibuf, length, 0);

  /* In case of IBGP, length will be zero. */
  if (! attr->aspath)
    {
      zlog (peer->log, LOG_ERR, "Malformed AS path length is %d", length);
      bgp_notify_send (peer, 
		       BGP_NOTIFY_UPDATE_ERR, 
		       BGP_NOTIFY_UPDATE_MAL_AS_PATH);
      return -1;
    }

  /* Forward pointer. */
/*  stream_forward_getp (peer->ibuf, length);*/

  /* Set aspath attribute flag. */
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_AS_PATH);

  return 0;
}

static int bgp_attr_aspath_check( struct peer *peer, 
		struct attr *attr)
{
  /* These checks were part of bgp_attr_aspath, but with
   * as4 we should to check aspath things when
   * aspath synthesizing with as4_aspath has already taken place.
   * Otherwise we check ASPATH and use the synthesized thing, and that is
   * not right.
   * So do the checks later, i.e. here
   */
  struct bgp *bgp = peer->bgp;
  struct aspath *aspath;

  bgp = peer->bgp;
    
  /* First AS check for EBGP. */
  if (bgp != NULL && bgp_flag_check (bgp, BGP_FLAG_ENFORCE_FIRST_AS))
    {
      if (peer_sort (peer) == BGP_PEER_EBGP 
	  && ! aspath_firstas_check (attr->aspath, peer->as))
 	{
 	  zlog (peer->log, LOG_ERR,
 		"%s incorrect first AS (must be %d)", peer->host, peer->as);
 	  bgp_notify_send (peer,
 			   BGP_NOTIFY_UPDATE_ERR,
 			   BGP_NOTIFY_UPDATE_MAL_AS_PATH);
	  return -1;
 	}
    }

  /* local-as prepend */
  if (peer->change_local_as &&
      ! CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND))
    {
      aspath = aspath_dup (attr->aspath);
      aspath = aspath_add_seq (aspath, peer->change_local_as);
      aspath_unintern (attr->aspath);
      attr->aspath = aspath_intern (aspath);
    }

  return 0;

}

/* Parse AS4 path information.  This function is another wrapper of
   aspath_parse. */
static int
bgp_attr_as4_aspath (struct peer *peer, bgp_size_t length, 
		 struct attr *attr, u_char flag, u_char *startp)
{
  attr->as4_aspath = aspath_parse (peer->ibuf, length, 1);

  /* Set aspath attribute flag. */
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_AS4_PATH);

  return 0;
}

/* Nexthop attribute. */
static int
bgp_attr_nexthop (struct peer *peer, bgp_size_t length, 
		  struct attr *attr, u_char flag, u_char *startp)
{
  bgp_size_t total;

  total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);

  /* Flag check. */
  if (CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL)
      || ! CHECK_FLAG (flag, BGP_ATTR_FLAG_TRANS))
    {
      zlog (peer->log, LOG_ERR, 
	    "Origin attribute flag isn't transitive %d", flag);
      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_ATTR_FLAG_ERR,
				 startp, total);
      return -1;
    }

  /* Check nexthop attribute length. */
  if (length != 4)
    {
      zlog (peer->log, LOG_ERR, "Nexthop attribute length isn't four [%d]",
	      length);

      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
				 startp, total);
      return -1;
    }

  attr->nexthop.s_addr = stream_get_ipv4 (peer->ibuf);
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_NEXT_HOP);

  return 0;
}

/* MED atrribute. */
static int
bgp_attr_med (struct peer *peer, bgp_size_t length, 
	      struct attr *attr, u_char flag, u_char *startp)
{
  bgp_size_t total;

  total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);

  /* Length check. */
  if (length != 4)
    {
      zlog (peer->log, LOG_ERR, 
	    "MED attribute length isn't four [%d]", length);
      
      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
				 startp, total);
      return -1;
    }

  attr->med = stream_getl (peer->ibuf);

  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_MULTI_EXIT_DISC);

  return 0;
}

/* Local preference attribute. */
static int
bgp_attr_local_pref (struct peer *peer, bgp_size_t length, 
		     struct attr *attr, u_char flag)
{
  /* If it is contained in an UPDATE message that is received from an
     external peer, then this attribute MUST be ignored by the
     receiving speaker. */
  if (peer_sort (peer) == BGP_PEER_EBGP)
    {
      stream_forward_getp (peer->ibuf, length);
      return 0;
    }

  if (length == 4) 
    attr->local_pref = stream_getl (peer->ibuf);
  else 
    attr->local_pref = 0;

  /* Set atomic aggregate flag. */
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_LOCAL_PREF);

  return 0;
}

/* Atomic aggregate. */
static int
bgp_attr_atomic (struct peer *peer, bgp_size_t length, 
		 struct attr *attr, u_char flag)
{
  if (length != 0)
    {
      zlog (peer->log, LOG_ERR, "Bad atomic aggregate length %d", length);

      bgp_notify_send (peer, 
		       BGP_NOTIFY_UPDATE_ERR, 
		       BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
      return -1;
    }

  /* Set atomic aggregate flag. */
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_ATOMIC_AGGREGATE);

  return 0;
}

/* Aggregator attribute */
static int
bgp_attr_aggregator (struct peer *peer, bgp_size_t length,
		     struct attr *attr, u_char flag)
{
  int wantedlen;

  /*
   * peer with AS4 will send 4 Byte AS, peer without will send 2 Byte
   */
  if ( CHECK_FLAG (peer->cap, PEER_CAP_AS4_RCV ) )
    wantedlen = 8;
  else
    wantedlen = 6;

  if (length != wantedlen)
    {
      zlog (peer->log, LOG_ERR, "Aggregator length is not %d [%d]", wantedlen, length);

      bgp_notify_send (peer,
		       BGP_NOTIFY_UPDATE_ERR,
		       BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
      return -1;
    }

  if ( CHECK_FLAG (peer->cap, PEER_CAP_AS4_RCV ) )
    attr->aggregator_as = stream_getl (peer->ibuf);
  else
    attr->aggregator_as = stream_getw (peer->ibuf);

  attr->aggregator_addr.s_addr = stream_get_ipv4 (peer->ibuf);

  /* Set atomic aggregate flag. */
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_AGGREGATOR);

  return 0;
}

/* New Aggregator attribute */
static int
bgp_attr_as4_aggregator (struct peer *peer, bgp_size_t length,
		     struct attr *attr, u_char flag)
{
  as_t as4_aggregator_as;
  u_int32_t as4_aggregator_address;

  if (length != 8)
    {
      zlog (peer->log, LOG_ERR, "New Aggregator length is not 8 [%d]", length);

      bgp_notify_send (peer,
		       BGP_NOTIFY_UPDATE_ERR,
		       BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
      return -1;
    }
  as4_aggregator_as = stream_getl (peer->ibuf);
  as4_aggregator_address = stream_get_ipv4 (peer->ibuf);
  /* Set atomic aggregate flag. */
  attr->as4_aggregator_as = as4_aggregator_as;
  attr->as4_aggregator_addr.s_addr = as4_aggregator_address;

  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_AS4_AGGREGATOR);

  return 0;
}

/* Community attribute. */
static int
bgp_attr_community (struct peer *peer, bgp_size_t length, 
		    struct attr *attr, u_char flag)
{
  if (length == 0)
    attr->community = NULL;
  else
    {
      attr->community = 
        community_parse ((u_int32_t *)stream_pnt (peer->ibuf), length);
      stream_forward_getp (peer->ibuf, length);
    }

  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES);

  return 0;
}

/* Originator ID attribute. */
static int
bgp_attr_originator_id (struct peer *peer, bgp_size_t length, 
			struct attr *attr, u_char flag)
{
  if (length != 4)
    {
      zlog (peer->log, LOG_ERR, "Bad originator ID length %d", length);

      bgp_notify_send (peer, 
		       BGP_NOTIFY_UPDATE_ERR, 
		       BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
      return -1;
    }

  attr->originator_id.s_addr = stream_get_ipv4 (peer->ibuf);

  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_ORIGINATOR_ID);

  return 0;
}

/* Cluster list attribute. */
static int
bgp_attr_cluster_list (struct peer *peer, bgp_size_t length, 
		       struct attr *attr, u_char flag)
{
  /* Check length. */
  if (length % 4)
    {
      zlog (peer->log, LOG_ERR, "Bad cluster list length %d", length);

      bgp_notify_send (peer, 
		       BGP_NOTIFY_UPDATE_ERR, 
		       BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
      return -1;
    }

  attr->cluster = cluster_parse ((struct in_addr *)stream_pnt (peer->ibuf), 
                                 length);

  stream_forward_getp (peer->ibuf, length);;

  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_CLUSTER_LIST);

  return 0;
}

/* Multiprotocol reachability information parse. */
static int
bgp_mp_reach_parse (struct peer *peer, bgp_size_t length, struct attr *attr,
		    struct bgp_nlri *mp_update)
{
  u_int16_t afi;
  u_char safi;
  u_char snpa_num;
  u_char snpa_len;
  u_char *lim;
  bgp_size_t nlri_len;
  int ret;
  struct stream *s;
  
  /* Set end of packet. */
  s = peer->ibuf;
  lim = stream_pnt (s) + length;

  /* Load AFI, SAFI. */
  afi = stream_getw (s);
  safi = stream_getc (s);

  /* Get nexthop length. */
  attr->mp_nexthop_len = stream_getc (s);

  /* Nexthop length check. */
  switch (attr->mp_nexthop_len)
    {
    case 4:
      stream_get (&attr->mp_nexthop_global_in, s, 4);
      break;
    case 12:
      {
	u_int32_t rd_high;
	u_int32_t rd_low;

	rd_high = stream_getl (s);
	rd_low = stream_getl (s);
	stream_get (&attr->mp_nexthop_global_in, s, 4);
      }
      break;
#ifdef HAVE_IPV6
    case 16:
      stream_get (&attr->mp_nexthop_global, s, 16);
      break;
    case 32:
      stream_get (&attr->mp_nexthop_global, s, 16);
      stream_get (&attr->mp_nexthop_local, s, 16);
      if (! IN6_IS_ADDR_LINKLOCAL (&attr->mp_nexthop_local))
	{
	  char buf1[INET6_ADDRSTRLEN];
	  char buf2[INET6_ADDRSTRLEN];

	  if (BGP_DEBUG (update, UPDATE_IN))
	    zlog_debug ("%s got two nexthop %s %s but second one is not a link-local nexthop", peer->host,
		       inet_ntop (AF_INET6, &attr->mp_nexthop_global,
				  buf1, INET6_ADDRSTRLEN),
		       inet_ntop (AF_INET6, &attr->mp_nexthop_local,
				  buf2, INET6_ADDRSTRLEN));

	  attr->mp_nexthop_len = 16;
	}
      break;
#endif /* HAVE_IPV6 */
    default:
      zlog_info ("Wrong multiprotocol next hop length: %d", 
		 attr->mp_nexthop_len);
      return -1;
    }

  snpa_num = stream_getc (s);

  while (snpa_num--)
    {
      snpa_len = stream_getc (s);
      stream_forward_getp (s, (snpa_len + 1) >> 1);
    }
  
  nlri_len = lim - stream_pnt (s);
 
  if (safi != BGP_SAFI_VPNV4)
    {
      ret = bgp_nlri_sanity_check (peer, afi, stream_pnt (s), nlri_len);
      if (ret < 0)
	return -1;
    }

  mp_update->afi = afi;
  mp_update->safi = safi;
  mp_update->nlri = stream_pnt (s);
  mp_update->length = nlri_len;

  stream_forward_getp (s, nlri_len);

  return 0;
}

/* Multiprotocol unreachable parse */
static int
bgp_mp_unreach_parse (struct peer *peer, int length, 
		      struct bgp_nlri *mp_withdraw)
{
  struct stream *s;
  u_int16_t afi;
  u_char safi;
  u_char *lim;
  u_int16_t withdraw_len;
  int ret;

  s = peer->ibuf;
  lim = stream_pnt (s) + length;

  afi = stream_getw (s);
  safi = stream_getc (s);

  withdraw_len = lim - stream_pnt (s);

  if (safi != BGP_SAFI_VPNV4)
    {
      ret = bgp_nlri_sanity_check (peer, afi, stream_pnt (s), withdraw_len);
      if (ret < 0)
	return -1;
    }

  mp_withdraw->afi = afi;
  mp_withdraw->safi = safi;
  mp_withdraw->nlri = stream_pnt (s);
  mp_withdraw->length = withdraw_len;

  stream_forward_getp (s, withdraw_len);

  return 0;
}

/* Extended Community attribute. */
static int
bgp_attr_ext_communities (struct peer *peer, bgp_size_t length, 
			  struct attr *attr, u_char flag)
{
  if (length == 0)
    attr->ecommunity = NULL;
  else
    {
      attr->ecommunity = 
        ecommunity_parse ((u_int8_t *)stream_pnt (peer->ibuf), length);
      stream_forward_getp (peer->ibuf, length);
    }
  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES);

  return 0;
}

/* BGP unknown attribute treatment. */
static int
bgp_attr_unknown (struct peer *peer, struct attr *attr, u_char flag,
		  u_char type, bgp_size_t length, u_char *startp)
{
  bgp_size_t total;
  struct transit *transit;

  if (BGP_DEBUG (normal, NORMAL))
  zlog_debug ("%s Unknown attribute is received (type %d, length %d)",
	      peer->host, type, length);
  
  if (BGP_DEBUG (events, EVENTS))
    zlog (peer->log, LOG_DEBUG, 
	  "Unknown attribute type %d length %d is received", type, length);

  /* Forward read pointer of input stream. */
  stream_forward_getp (peer->ibuf, length);

  /* Adjest total length to include type and length. */
  total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);

  /* If any of the mandatory well-known attributes are not recognized,
     then the Error Subcode is set to Unrecognized Well-known
     Attribute.  The Data field contains the unrecognized attribute
     (type, length and value). */
  if (! CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL))
    {
      /* Adjust startp to do not include flag value. */
      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_UNREC_ATTR,
				 startp, total);
      return -1;
    }

  /* Unrecognized non-transitive optional attributes must be quietly
     ignored and not passed along to other BGP peers. */
  if (! CHECK_FLAG (flag, BGP_ATTR_FLAG_TRANS))
    return 0;

  /* If a path with recognized transitive optional attribute is
     accepted and passed along to other BGP peers and the Partial bit
     in the Attribute Flags octet is set to 1 by some previous AS, it
     is not set back to 0 by the current AS. */
  SET_FLAG (*startp, BGP_ATTR_FLAG_PARTIAL);

  /* Store transitive attribute to the end of attr->transit. */
  if (! attr->transit)
    {
      attr->transit = XMALLOC (MTYPE_TRANSIT, sizeof (struct transit));
      memset (attr->transit, 0, sizeof (struct transit));
    }

  transit = attr->transit;

  if (transit->val)
    transit->val = XREALLOC (MTYPE_TRANSIT_VAL, transit->val, 
			     transit->length + total);
  else
    transit->val = XMALLOC (MTYPE_TRANSIT_VAL, total);

  memcpy (transit->val + transit->length, startp, total);
  transit->length += total;

  return 0;
}

/* Read attribute of update packet.  This function is called from
   bgp_update() in bgpd.c.  */
int
bgp_attr_parse (struct peer *peer, struct attr *attr, bgp_size_t size,
		struct bgp_nlri *mp_update, struct bgp_nlri *mp_withdraw)
{
  int ret;
  u_char flag;
  u_char type;
  bgp_size_t length;
  u_char *startp, *endp;
  u_char *attr_endp;
  u_char seen[BGP_ATTR_BITMAP_SIZE];

  /* Initialize bitmap. */
  memset (seen, 0, BGP_ATTR_BITMAP_SIZE);

  /* End pointer of BGP attribute. */
  endp = BGP_INPUT_PNT (peer) + size;

  /* Get attributes to the end of attribute length. */
  while (BGP_INPUT_PNT (peer) < endp)
    {
      /* Check remaining length check.*/
      if (endp - BGP_INPUT_PNT (peer) < BGP_ATTR_MIN_LEN)
	{
	  /* XXX warning: long int format, int arg (arg 5) */
	  zlog (peer->log, LOG_WARNING, 
		"%s error BGP attribute length %ld is smaller than min len",
		peer->host, endp - STREAM_PNT (BGP_INPUT (peer)));

	  bgp_notify_send (peer, 
			   BGP_NOTIFY_UPDATE_ERR, 
			   BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
	  return -1;
	}

      /* Fetch attribute flag and type. */
      startp = BGP_INPUT_PNT (peer);
      flag = stream_getc (BGP_INPUT (peer));
      type = stream_getc (BGP_INPUT (peer));

      /* Check extended attribue length bit. */
      if (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN))
	length = stream_getw (BGP_INPUT (peer));
      else
	length = stream_getc (BGP_INPUT (peer));
      
      /* If any attribute appears more than once in the UPDATE
	 message, then the Error Subcode is set to Malformed Attribute
	 List. */

      if (CHECK_BITMAP (seen, type))
	{
	  zlog (peer->log, LOG_WARNING,
		"%s error BGP attribute type %d appears twice in a message",
		peer->host, type);

	  bgp_notify_send (peer, 
			   BGP_NOTIFY_UPDATE_ERR, 
			   BGP_NOTIFY_UPDATE_MAL_ATTR);
	  return -1;
	}

      /* Set type to bitmap to check duplicate attribute.  `type' is
	 unsigned char so it never overflow bitmap range. */

      SET_BITMAP (seen, type);

      /* Overflow check. */
      attr_endp =  BGP_INPUT_PNT (peer) + length;

      if (attr_endp > endp)
	{
	  zlog (peer->log, LOG_WARNING, 
		"%s BGP type %d length %d is too large, attribute total length is %d.  attr_endp is %p.  endp is %p", peer->host, type, length, size, attr_endp, endp);
	  bgp_notify_send (peer, 
			   BGP_NOTIFY_UPDATE_ERR, 
			   BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
	  return -1;
	}

      /* OK check attribute and store it's value. */
      switch (type)
	{
	case BGP_ATTR_ORIGIN:
	  ret = bgp_attr_origin (peer, length, attr, flag, startp);
	  break;
	case BGP_ATTR_AS_PATH:
	  ret = bgp_attr_aspath (peer, length, attr, flag, startp);
	  break;
	case BGP_ATTR_AS4_PATH:
	  ret = bgp_attr_as4_aspath (peer, length, attr, flag, startp);
	  break;
	case BGP_ATTR_NEXT_HOP:	
	  ret = bgp_attr_nexthop (peer, length, attr, flag, startp);
	  break;
	case BGP_ATTR_MULTI_EXIT_DISC:
	  ret = bgp_attr_med (peer, length, attr, flag, startp);
	  break;
	case BGP_ATTR_LOCAL_PREF:
	  ret = bgp_attr_local_pref (peer, length, attr, flag);
	  break;
	case BGP_ATTR_ATOMIC_AGGREGATE:
	  ret = bgp_attr_atomic (peer, length, attr, flag);
	  break;
	case BGP_ATTR_AGGREGATOR:
	  ret = bgp_attr_aggregator (peer, length, attr, flag);
	  break;
	case BGP_ATTR_AS4_AGGREGATOR:
	  ret = bgp_attr_as4_aggregator (peer, length, attr, flag);
	  break;
	case BGP_ATTR_COMMUNITIES:
	  ret = bgp_attr_community (peer, length, attr, flag);
	  break;
	case BGP_ATTR_ORIGINATOR_ID:
	  ret = bgp_attr_originator_id (peer, length, attr, flag);
	  break;
	case BGP_ATTR_CLUSTER_LIST:
	  ret = bgp_attr_cluster_list (peer, length, attr, flag);
	  break;
	case BGP_ATTR_MP_REACH_NLRI:
	  ret = bgp_mp_reach_parse (peer, length, attr, mp_update);
	  break;
	case BGP_ATTR_MP_UNREACH_NLRI:
	  ret = bgp_mp_unreach_parse (peer, length, mp_withdraw);
	  break;
	case BGP_ATTR_EXT_COMMUNITIES:
	  ret = bgp_attr_ext_communities (peer, length, attr, flag);
	  break;
	default:
	  ret = bgp_attr_unknown (peer, attr, flag, type, length, startp);
	  break;
	}

      /* If error occured immediately return to the caller. */
      if (ret < 0)
	return ret;

      /* Check the fetched length. */
      if (BGP_INPUT_PNT (peer) != attr_endp)
	{
	  zlog (peer->log, LOG_WARNING, 
		"%s BGP attribute fetch error", peer->host);
	  bgp_notify_send (peer, 
			   BGP_NOTIFY_UPDATE_ERR, 
			   BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
	  return -1;
	}
    }

  /* Check final read pointer is same as end pointer. */
  if (BGP_INPUT_PNT (peer) != endp)
    {
      zlog (peer->log, LOG_WARNING, 
	    "%s BGP attribute length mismatch", peer->host);
      bgp_notify_send (peer, 
		       BGP_NOTIFY_UPDATE_ERR, 
		       BGP_NOTIFY_UPDATE_ATTR_LENG_ERR);
      return -1;
    }

  /* 
   * At this place we can see whether we got AS4_PATH and/or
   * AS4_AGGREGATOR from a 16Bit peer and act accordingly.
   * We can not do this before we've read all attributes because
   * the as4 handling does not say whether AS4_PATH has to be sent
   * after AS_PATH or not - and when AS4_AGGREGATOR will be send
   * in relationship to AGGREGATOR.
   * So, to be defensive, we are not relying on any order and read
   * all attributes first, including these 32bit ones, and now,
   * afterwards, we look what and if something is to be done for as4.
   */

  if ( CHECK_FLAG (peer->cap, PEER_CAP_AS4_RCV ) )
    {
      /* peer can do AS4, so we ignore AS4_PATH and AS4_AGGREGATOR
       * if given.
       * It is worth a warning though, because the peer really
       * should not send them
       */
      if ( CHECK_BITMAP (seen, BGP_ATTR_AS4_PATH) )
        {
	  if ( BGP_DEBUG(as4, AS4))
	       zlog_debug ( "[AS4] %s BGP AS4 capable peer send AS4_PATH", peer->host);
	}
      if ( CHECK_BITMAP (seen, BGP_ATTR_AS4_AGGREGATOR) )
        {
	  if ( BGP_DEBUG(as4, AS4))
	    zlog_debug ( "[AS4] %s BGP AS4 capable peer send AS4_AGGREGATOR", peer->host);
	}
    }
  else
    {
      /* We have a asn16 peer.  First, look for AS4_AGGREGATOR
       * because that may override AS4_PATH
       */
      int ignore_as4_aspath = 0;
      if ( attr->flag & (ATTR_FLAG_BIT (BGP_ATTR_AS4_AGGREGATOR) ) )
	{
	  if ( attr->flag & (ATTR_FLAG_BIT (BGP_ATTR_AGGREGATOR) ) )
	    {
	      /* received both.
	       * if the as_number in aggregator is not AS_TRANS,
	       *  then AS4_AGGREGATOR and AS4_PATH shall be ignored
	       *        and the Aggregator shall be taken as 
	       *        info on the aggregating node, and the AS_PATH
	       *        shall be taken as the AS_PATH
	       *  otherwise
	       *        the Aggregator shall be ignored and the
	       *        AS4_AGGREGATOR shall be taken as the
	       *        Aggregating node and the AS_PATH is to be
	       *        constructed "as in all other cases"
	       */
	      if ( attr->aggregator_as != BGP_AS_TRANS )
		{
		  /* ignore */
		  if ( BGP_DEBUG(as4, AS4))
		    zlog_debug (
			"[AS4] %s BGP not AS4 capable peer send AGGREGATOR != AS_TRANS and AS4_AGGREGATOR, so ignore AS4_AGGREGATOR and AS4_PATH", peer->host);
		  ignore_as4_aspath = 1;
		}
	      else
		{
		  /* "New_aggregator shall be taken as aggregator" */
		  attr->aggregator_as = attr->as4_aggregator_as;
                  attr->aggregator_addr.s_addr = attr->as4_aggregator_addr.s_addr;
		}
	    }
	  else
	    {
	      /* We received a AS4_AGGREGATOR but no AGGREGATOR.
	       * That is bogus - but reading the conditions
	       * we have to handle AS4_AGGREGATOR as if it were
	       * AGGREGATOR in that case
	       */
	      if ( BGP_DEBUG(as4, AS4))
		zlog_debug (
		      "[AS4] %s BGP not AS4 capable peer send AS4_AGGREGATOR but no AGGREGATOR, will take it as if AGGREGATOR with AS_TRANS had been there", peer->host);
	      attr->aggregator_as = attr->as4_aggregator_as;
	      /* sweep it under the carpet and simulate a "good" AGGREGATOR */
	      SET_BITMAP (seen, BGP_ATTR_AGGREGATOR);
	      attr->flag |= (ATTR_FLAG_BIT (BGP_ATTR_AGGREGATOR));
	    }
	}
      if ( !ignore_as4_aspath && (attr->flag & ( ATTR_FLAG_BIT( BGP_ATTR_AS4_PATH))) )
	{
	  if ( ! (attr->flag & ( ATTR_FLAG_BIT( BGP_ATTR_AS_PATH))))
	    {
	      /* Hu? This is not supposed to happen at all!
	       * got as4_aspath and no aspath,
	       *   This should already
	       *   have been handled by 'well known attributes missing'
	       *   But... yeah, paranoia
	       * Take this as a "malformed attribute"
	       */
	      zlog (peer->log, LOG_ERR, 
		    "%s BGP not AS4 capable peer sent AS4_PATH but no AS_PATH, cant do anything here", peer->host);
	      bgp_notify_send (peer, 
			       BGP_NOTIFY_UPDATE_ERR, 
			       BGP_NOTIFY_UPDATE_MAL_ATTR);
	      return -1;
	    }
	  /* We have AS4_PATH AND AS_PATH
	   * Calculate the number of as numbers in both attributes!
	   *  What is meant is the number of "hops"!
	   *   if numas_in_aspath < numas_in_as4_aspath =>
	   *     ignore AS4_PATH, take AS_PATH.
	   *   else
	   *     take as many as_numbers and path segments from AS_PATH
	   *     and prepend them to AS4_PATH so that
	   *       num_new = numas_in_aspath
	   *      the resulting thing is our AS_PATH
	   *  An AS_SET or AS_CONFED_SET is one hop
	   *  every other thing has as many hops as asnums
	   */
	  int hopnumdiff = aspath_count_hops( attr->aspath ) - aspath_count_hops( attr->as4_aspath );

	  if ( BGP_DEBUG(as4, AS4))
	    zlog_debug (
		"[AS4] %s fiddling with aspath and newaspath, hopnumdifference is %d",
			peer->host, hopnumdiff);
	  if ( hopnumdiff >= 0 )
	    {
	      if ( BGP_DEBUG(as4, AS4))
		zlog_debug(
		  "[AS4] %s got AS_PATH %s and AS4_PATH %s synthesizing now", peer->host, attr->aspath->str, attr->as4_aspath->str);
	      aspath_truncateathopsandjoin( &attr->aspath, &attr->as4_aspath, hopnumdiff );
	      if ( BGP_DEBUG(as4, AS4))
		zlog_debug(
		  "[AS4] %s result of synthesizing is %s", peer->host, attr->aspath->str);
	    }
	}
    }

  /* At this stage, we have done all fiddling with as4, and the
   * resulting info is in attr->aggregator resp. attr->aspath
   * so we can chuck as4_aggregator and as4_aspath alltogether in
   * order to save memory
   */
  if ( attr->as4_aspath )
    {
      aspath_unintern( attr->as4_aspath ); /* unintern - it is in the hash */
      attr->as4_aspath = NULL;
      /* The flag that we got this is still there, but that does not
       * do any trouble
       */
    }
  /*
   * The "rest" of the code does nothing with as4_aggregator.
   * there is no memory attached specifically which is not part
   * of the attr.
   * so ignoring just means do nothing.
   */
  /*
   * Finally do the checks on the aspath we did not do yet
   * because we waited for a potentially synthesized aspath.
   */
  if ( attr->flag & ( ATTR_FLAG_BIT( BGP_ATTR_AS_PATH)))
    {
      ret = bgp_attr_aspath_check( peer, attr );
      if ( ret < 0 )
	return ret;
    }

  /* Finally intern unknown attribute. */
  if (attr->transit)
    attr->transit = transit_intern (attr->transit);

  return 0;
}

/* Well-known attribute check. */
int
bgp_attr_check (struct peer *peer, struct attr *attr)
{
  u_char type = 0;
  
  if (! CHECK_FLAG (attr->flag, ATTR_FLAG_BIT (BGP_ATTR_ORIGIN)))
    type = BGP_ATTR_ORIGIN;

  if (! CHECK_FLAG (attr->flag, ATTR_FLAG_BIT (BGP_ATTR_AS_PATH)))
    type = BGP_ATTR_AS_PATH;

  if (! CHECK_FLAG (attr->flag, ATTR_FLAG_BIT (BGP_ATTR_NEXT_HOP)))
    type = BGP_ATTR_NEXT_HOP;

  if (peer_sort (peer) == BGP_PEER_IBGP
      && ! CHECK_FLAG (attr->flag, ATTR_FLAG_BIT (BGP_ATTR_LOCAL_PREF)))
    type = BGP_ATTR_LOCAL_PREF;

  if (type)
    {
      zlog (peer->log, LOG_WARNING, 
	    "%s Missing well-known attribute %d.",
	    peer->host, type);
      bgp_notify_send_with_data (peer, 
				 BGP_NOTIFY_UPDATE_ERR, 
				 BGP_NOTIFY_UPDATE_MISS_ATTR,
				 &type, 1);
      return -1;
    }
  return 0;
}

int stream_put_prefix (struct stream *, struct prefix *);

/* Make attribute packet. */
bgp_size_t
bgp_packet_attribute (struct bgp *bgp, struct peer *peer,
		      struct stream *s, struct attr *attr, struct prefix *p,
		      afi_t afi, safi_t safi, struct peer *from,
		      struct prefix_rd *prd, u_char *tag)
{
  size_t cp;
  unsigned int aspath_data_size;
  unsigned int numas;
  struct aspath *aspath;

  if (! bgp)
    bgp = bgp_get_default ();

  /* Remember current pointer. */
  cp = stream_get_endp (s);

  /* Origin attribute. */
  stream_putc (s, BGP_ATTR_FLAG_TRANS);
  stream_putc (s, BGP_ATTR_ORIGIN);
  stream_putc (s, 1);
  stream_putc (s, attr->origin);

  /* AS path attribute. */

  /* If remote-peer is EBGP */
  if (peer_sort (peer) == BGP_PEER_EBGP
      && (! CHECK_FLAG (peer->af_flags[afi][safi], PEER_FLAG_AS_PATH_UNCHANGED)
	  || attr->aspath->segments == NULL)
      && (! CHECK_FLAG (peer->af_flags[afi][safi], PEER_FLAG_RSERVER_CLIENT)))
    {    
      aspath = aspath_dup (attr->aspath);

      if (CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION))
	{
	  /* Strip the confed info, and then stuff our path CONFED_ID
	     on the front */
	  aspath = aspath_delete_confed_seq (aspath);
	  aspath = aspath_add_seq (aspath, bgp->confed_id);
	}
      else
	{
	  aspath = aspath_add_seq (aspath, peer->local_as);
	  if (peer->change_local_as)
	    aspath = aspath_add_seq (aspath, peer->change_local_as);
	}
    }
  else if (peer_sort (peer) == BGP_PEER_CONFED)
    {
      /* A confed member, so we need to do the AS_CONFED_SEQUENCE thing */
      aspath = aspath_dup (attr->aspath);
      aspath = aspath_add_confed_seq (aspath, peer->local_as);
    }
  else
    aspath = attr->aspath;

  /* If peer is not AS4 capable, then:
   * - send the created AS_PATH out as AS4_PATH (optional, transitive),
   *   but ensure that no AS_CONFED_SEQUENCE and AS_CONFED_SET path segment
   *   types are in it (i.e. exclude them if they are there)
   *   AND do this only if there is at least one asnum > 65535 in the path!
   * - send an AS_PATH out, but put 16Bit ASnums in it, not 32bit, and change
   *   all ASnums > 65535 to BGP_AS_TRANS
   *
   * Beware: aspath_data_size is ONLY correct if there is no aspath segment
   * longer 255, and no two segments which are able to be merged
   * That thing is in the code for a looonng time and nobody bothers.
   */

  /* AS path attribute extended length bit check. */
  aspath_data_size = aspath_size (aspath);
  numas = aspath_count_numas( aspath );

  if ( CHECK_FLAG (peer->cap, PEER_CAP_AS4_RCV ) )
    {
      /* this is the easy part, peer is as4 capable, send 4 byte aspath */
      if (aspath_data_size > 255)
	{
	  stream_putc (s, BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
	  stream_putc (s, BGP_ATTR_AS_PATH);
	  stream_putw (s, aspath_data_size);
	}
      else
	{
	  stream_putc (s, BGP_ATTR_FLAG_TRANS);
	  stream_putc (s, BGP_ATTR_AS_PATH);
	  stream_putc (s, aspath_data_size);
	}
      aspath_put (s, aspath, 1);
    }
  else
    {
      /*
       * size of 16bit aspath is smaller by number of asnums * 2Bytes
       * actually, number os asnums * (sizeof(as_t) - sizeof(as16_t)),
       * but that is nit-picking.
       */
      if (aspath_data_size - 2*numas > 255)
	{
	  stream_putc (s, BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
	  stream_putc (s, BGP_ATTR_AS_PATH);
	  stream_putw (s, aspath_data_size - 2*numas );
	}
      else
	{
	  stream_putc (s, BGP_ATTR_FLAG_TRANS);
	  stream_putc (s, BGP_ATTR_AS_PATH);
	  stream_putc (s, aspath_data_size - 2*numas );
	}
      aspath_put (s, aspath, 0);

      if ( aspath_count_num32as( aspath ) > 0 )
        {
	  /* put out AS4_PATH (only if there are ASnums > 65535 in path */

	  /* Get rid of all AS_CONFED_SEQUENCE and AS_CONFED_SET
	   * path segments!
	   * Hm, I wonder...  confederation things *should* only be at
	   * the beginning of an aspath, right?  Then we should use
	   * aspath_delete_confed_seq for this, because it is already
	   * there! (JK) 
	   * Folks, talk to me: what is reasonable here!?
	   */
	  if ( aspath_count_confeds(aspath) > 0 ) {
	    aspath_cleanoutall_asconfeds( &aspath, &aspath_data_size );
	  }

	  if (aspath_data_size > 255)
	    {
	      stream_putc (s, BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_EXTLEN);
	      stream_putc (s, BGP_ATTR_AS4_PATH);
	      stream_putw (s, aspath_data_size);
	    }
	  else
	    {
	      stream_putc (s, BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_OPTIONAL);
	      stream_putc (s, BGP_ATTR_AS4_PATH);
	      stream_putc (s, aspath_data_size);
	    }
	  aspath_put (s, aspath, 1);
        }
    }

  if (aspath != attr->aspath)
    aspath_free (aspath);

  /* Nexthop attribute. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_NEXT_HOP) && afi == AFI_IP)
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_NEXT_HOP);
      stream_putc (s, 4);
      if (safi == SAFI_MPLS_VPN)
	{
	  if (attr->nexthop.s_addr == 0)
	    stream_put_ipv4 (s, peer->nexthop.v4.s_addr);
	  else
	    stream_put_ipv4 (s, attr->nexthop.s_addr);
	}
      else
	stream_put_ipv4 (s, attr->nexthop.s_addr);
    }

  /* MED attribute. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_MULTI_EXIT_DISC))
    {
      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc (s, BGP_ATTR_MULTI_EXIT_DISC);
      stream_putc (s, 4);
      stream_putl (s, attr->med);
    }

  /* Local preference. */
  if (peer_sort (peer) == BGP_PEER_IBGP ||
      peer_sort (peer) == BGP_PEER_CONFED)
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_LOCAL_PREF);
      stream_putc (s, 4);
      stream_putl (s, attr->local_pref);
    }

  /* Atomic aggregate. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_ATOMIC_AGGREGATE))
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_ATOMIC_AGGREGATE);
      stream_putc (s, 0);
    }

  /* Aggregator. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_AGGREGATOR))
    {
	  /* If peer is AS4 capable,
	   * then
	   *    send BGP_ATTR_AGGREGATOR with 32 bit AS value
	   * else
	   *   if attr->aggregator_as > 65535
	   *    change the aggregator_as in the AGGREGATOR to AS_TRANS
	   *    and send out a AS4_AGGREGATOR (opt, transitional)
	   *    with the correct 4 Bytes thingy.
	   *   else
	   *    proceed as you always did
	   */
      if ( CHECK_FLAG (peer->cap, PEER_CAP_AS4_RCV ) )
        {
	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
	  stream_putc (s, BGP_ATTR_AGGREGATOR);
	  stream_putc (s, 8);
	  stream_putl (s, attr->aggregator_as);
	  stream_put_ipv4 (s, attr->aggregator_addr.s_addr);
        }
      else
        {
	  if ( attr->aggregator_as > 65535 )
	    {
	      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
	      stream_putc (s, BGP_ATTR_AGGREGATOR);
	      stream_putc (s, 6);
	      stream_putw (s, BGP_AS_TRANS);
	      stream_put_ipv4 (s, attr->aggregator_addr.s_addr);

	      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
	      stream_putc (s, BGP_ATTR_AS4_AGGREGATOR);
	      stream_putc (s, 8);
	      stream_putl (s, attr->aggregator_as);
	      stream_put_ipv4 (s, attr->aggregator_addr.s_addr);
	    }
	  else
	    {
	      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
	      stream_putc (s, BGP_ATTR_AGGREGATOR);
	      stream_putc (s, 6);
	      stream_putw (s, (u_int16_t) attr->aggregator_as);
	      stream_put_ipv4 (s, attr->aggregator_addr.s_addr);
	    }
	}
    }

  /* Community attribute. */
  if (CHECK_FLAG (peer->af_flags[afi][safi], PEER_FLAG_SEND_COMMUNITY) 
      && (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES)))
    {
      if (attr->community->size * 4 > 255)
	{
	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
	  stream_putc (s, BGP_ATTR_COMMUNITIES);
	  stream_putw (s, attr->community->size * 4);
	}
      else
	{
	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
	  stream_putc (s, BGP_ATTR_COMMUNITIES);
	  stream_putc (s, attr->community->size * 4);
	}
      stream_put (s, attr->community->val, attr->community->size * 4);
    }

  /* Route Reflector. */
  if (peer_sort (peer) == BGP_PEER_IBGP
      && from
      && peer_sort (from) == BGP_PEER_IBGP)
    {
      /* Originator ID. */
      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc (s, BGP_ATTR_ORIGINATOR_ID);
      stream_putc (s, 4);

      if (attr->flag & ATTR_FLAG_BIT(BGP_ATTR_ORIGINATOR_ID))
	stream_put_in_addr (s, &attr->originator_id);
      else 
        stream_put_in_addr (s, &from->remote_id);

      /* Cluster list. */
      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc (s, BGP_ATTR_CLUSTER_LIST);
      
      if (attr->cluster)
	{
	  stream_putc (s, attr->cluster->length + 4);
	  /* If this peer configuration's parent BGP has cluster_id. */
	  if (bgp->config & BGP_CONFIG_CLUSTER_ID)
	    stream_put_in_addr (s, &bgp->cluster_id);
	  else
	    stream_put_in_addr (s, &bgp->router_id);
	  stream_put (s, attr->cluster->list, attr->cluster->length);
	}
      else
	{
	  stream_putc (s, 4);
	  /* If this peer configuration's parent BGP has cluster_id. */
	  if (bgp->config & BGP_CONFIG_CLUSTER_ID)
	    stream_put_in_addr (s, &bgp->cluster_id);
	  else
	    stream_put_in_addr (s, &bgp->router_id);
	}
    }

#ifdef HAVE_IPV6
  /* If p is IPv6 address put it into attribute. */
  if (p->family == AF_INET6)
    {
      unsigned long sizep;

      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc (s, BGP_ATTR_MP_REACH_NLRI);
      sizep = stream_get_endp (s);
      stream_putc (s, 0);	/* Length of this attribute. */
      stream_putw (s, AFI_IP6);	/* AFI */
      stream_putc (s, safi);	/* SAFI */

      stream_putc (s, attr->mp_nexthop_len);

      if (attr->mp_nexthop_len == 16)
	stream_put (s, &attr->mp_nexthop_global, 16);
      else if (attr->mp_nexthop_len == 32)
	{
	  stream_put (s, &attr->mp_nexthop_global, 16);
	  stream_put (s, &attr->mp_nexthop_local, 16);
	}
      
      /* SNPA */
      stream_putc (s, 0);

      /* Prefix write. */
      stream_put_prefix (s, p);

      /* Set MP attribute length. */
      stream_putc_at (s, sizep, (stream_get_endp (s) - sizep) - 1);
    }
#endif /* HAVE_IPV6 */

  if (p->family == AF_INET && safi == SAFI_MULTICAST)
    {
      unsigned long sizep;

      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc (s, BGP_ATTR_MP_REACH_NLRI);
      sizep = stream_get_endp (s);
      stream_putc (s, 0);	/* Length of this attribute. */
      stream_putw (s, AFI_IP);	/* AFI */
      stream_putc (s, SAFI_MULTICAST);	/* SAFI */

      stream_putc (s, 4);
      stream_put_ipv4 (s, attr->nexthop.s_addr);

      /* SNPA */
      stream_putc (s, 0);

      /* Prefix write. */
      stream_put_prefix (s, p);

      /* Set MP attribute length. */
      stream_putc_at (s, sizep, (stream_get_endp (s) - sizep) - 1);
    }

  if (p->family == AF_INET && safi == SAFI_MPLS_VPN)
    {
      unsigned long sizep;

      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc (s, BGP_ATTR_MP_REACH_NLRI);
      sizep = stream_get_endp (s);
      stream_putc (s, 0);	/* Length of this attribute. */
      stream_putw (s, AFI_IP);	/* AFI */
      stream_putc (s, BGP_SAFI_VPNV4);	/* SAFI */

      stream_putc (s, 12);
      stream_putl (s, 0);
      stream_putl (s, 0);
      stream_put (s, &attr->mp_nexthop_global_in, 4);

      /* SNPA */
      stream_putc (s, 0);

      /* Tag, RD, Prefix write. */
      stream_putc (s, p->prefixlen + 88);
      stream_put (s, tag, 3);
      stream_put (s, prd->val, 8);
      stream_put (s, &p->u.prefix, PSIZE (p->prefixlen));

      /* Set MP attribute length. */
      stream_putc_at (s, sizep, (stream_get_endp (s) - sizep) - 1);
    }

  /* Extended Communities attribute. */
  if (CHECK_FLAG (peer->af_flags[afi][safi], PEER_FLAG_SEND_EXT_COMMUNITY) 
      && (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES)))
    {
      if (peer_sort (peer) == BGP_PEER_IBGP || peer_sort (peer) == BGP_PEER_CONFED)
	{
	  if (attr->ecommunity->size * 8 > 255)
	    {
	      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
	      stream_putc (s, BGP_ATTR_EXT_COMMUNITIES);
	      stream_putw (s, attr->ecommunity->size * 8);
	    }
	  else
	    {
	      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
	      stream_putc (s, BGP_ATTR_EXT_COMMUNITIES);
	      stream_putc (s, attr->ecommunity->size * 8);
	    }
	  stream_put (s, attr->ecommunity->val, attr->ecommunity->size * 8);
	}
      else
	{
	  u_int8_t *pnt;
	  int tbit;
	  int ecom_tr_size = 0;
	  int i;

	  for (i = 0; i < attr->ecommunity->size; i++)
	    {
	      pnt = attr->ecommunity->val + (i * 8);
	      tbit = *pnt;

	      if (CHECK_FLAG (tbit, ECOMMUNITY_FLAG_NON_TRANSITIVE))
		continue;

	      ecom_tr_size++;
	    }

	  if (ecom_tr_size)
	    {
	      if (ecom_tr_size * 8 > 255)
		{
		  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
		  stream_putc (s, BGP_ATTR_EXT_COMMUNITIES);
		  stream_putw (s, ecom_tr_size * 8);
		}
	      else
		{
		  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
		  stream_putc (s, BGP_ATTR_EXT_COMMUNITIES);
		  stream_putc (s, ecom_tr_size * 8);
		}

	      for (i = 0; i < attr->ecommunity->size; i++)
		{
		  pnt = attr->ecommunity->val + (i * 8);
		  tbit = *pnt;

		  if (CHECK_FLAG (tbit, ECOMMUNITY_FLAG_NON_TRANSITIVE))
		    continue;

		  stream_put (s, pnt, 8);
		}
	    }
	}
    }

  /* Unknown transit attribute. */
  if (attr->transit)
    stream_put (s, attr->transit->val, attr->transit->length);

  /* Return total size of attribute. */
  return stream_get_endp (s) - cp;
}

bgp_size_t
bgp_packet_withdraw (struct peer *peer, struct stream *s, struct prefix *p,
		     afi_t afi, safi_t safi, struct prefix_rd *prd,
		     u_char *tag)
{
  unsigned long cp;
  unsigned long attrlen_pnt;
  bgp_size_t size;

  cp = stream_get_endp (s);

  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
  stream_putc (s, BGP_ATTR_MP_UNREACH_NLRI);

  attrlen_pnt = stream_get_endp (s);
  stream_putc (s, 0);		/* Length of this attribute. */

  stream_putw (s, family2afi (p->family));

  if (safi == SAFI_MPLS_VPN)
    {
      /* SAFI */
      stream_putc (s, BGP_SAFI_VPNV4);

      /* prefix. */
      stream_putc (s, p->prefixlen + 88);
      stream_put (s, tag, 3);
      stream_put (s, prd->val, 8);
      stream_put (s, &p->u.prefix, PSIZE (p->prefixlen));
    }
  else
    {
      /* SAFI */
      stream_putc (s, safi);

      /* prefix */
      stream_put_prefix (s, p);
    }

  /* Set MP attribute length. */
  size = stream_get_endp (s) - attrlen_pnt - 1;
  stream_putc_at (s, attrlen_pnt, size);

  return stream_get_endp (s) - cp;
}

/* Initialization of attribute. */
void
bgp_attr_init (void)
{
  void attrhash_init ();

  aspath_init ();
  attrhash_init ();
  community_init ();
  ecommunity_init ();
  cluster_init ();
  transit_init ();
}

/* Make attribute packet. */
void
bgp_dump_routes_attr (struct stream *s, struct attr *attr, 
                      struct prefix *prefix, int dump_small_mp_nlri)
{
  unsigned long cp;
  unsigned long len;
  unsigned int aspathlen;
  struct aspath *aspath;

  /* Remember current pointer. */
  cp = stream_get_endp (s);

  /* Place holder of length. */
  stream_putw (s, 0);

  /* Origin attribute. */
  stream_putc (s, BGP_ATTR_FLAG_TRANS);
  stream_putc (s, BGP_ATTR_ORIGIN);
  stream_putc (s, 1);
  stream_putc (s, attr->origin);

  aspath = attr->aspath;

  if ( (aspathlen = aspath_size (aspath)) > 255 )
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
      stream_putc (s, BGP_ATTR_AS_PATH);
      stream_putw (s, aspathlen);
    }
  else
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_AS_PATH);
      stream_putc (s, aspathlen);
    }
  aspath_put (s, aspath, 1); /* always 32bit. aspath_put size remarks apply */

  /* Nexthop attribute. */
  /* If it's an IPv6 prefix, don't dump the IPv4 nexthop to save space */
  if(prefix != NULL
#ifdef HAVE_IPV6
     && prefix->family != AF_INET6
#endif /* HAVE_IPV6 */
     )
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_NEXT_HOP);
      stream_putc (s, 4);
      stream_put_ipv4 (s, attr->nexthop.s_addr);
    }

  /* MED attribute. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_MULTI_EXIT_DISC))
    {
      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc (s, BGP_ATTR_MULTI_EXIT_DISC);
      stream_putc (s, 4);
      stream_putl (s, attr->med);
    }

  /* Local preference. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_LOCAL_PREF))
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_LOCAL_PREF);
      stream_putc (s, 4);
      stream_putl (s, attr->local_pref);
    }

  /* Atomic aggregate. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_ATOMIC_AGGREGATE))
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_ATOMIC_AGGREGATE);
      stream_putc (s, 0);
    }

  /* Aggregator. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_AGGREGATOR))
    {
      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_AGGREGATOR);
      stream_putc (s, 8);
      stream_putl (s, attr->aggregator_as);
      stream_put_ipv4 (s, attr->aggregator_addr.s_addr);
    }

  /* Community attribute. */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES))
    {
      if (attr->community->size * 4 > 255)
	{
	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
	  stream_putc (s, BGP_ATTR_COMMUNITIES);
	  stream_putw (s, attr->community->size * 4);
	}
      else
	{
	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
	  stream_putc (s, BGP_ATTR_COMMUNITIES);
	  stream_putc (s, attr->community->size * 4);
	}
      stream_put (s, attr->community->val, attr->community->size * 4);
    }

#ifdef HAVE_IPV6
  /* Add a MP_NLRI attribute to dump the IPv6 next hop */
  if(prefix != NULL && prefix->family == AF_INET6 && 
     (attr->mp_nexthop_len == 16 || attr->mp_nexthop_len == 32) )
    {
      int sizep;

      stream_putc(s, BGP_ATTR_FLAG_OPTIONAL);
      stream_putc(s, BGP_ATTR_MP_REACH_NLRI);
      sizep = stream_get_endp (s);

      /* MP header */
      stream_putc (s, 0);		/* Length of this attribute. */
      if(!dump_small_mp_nlri)
        {
          stream_putw(s, AFI_IP6);		/* AFI */
          stream_putc(s, SAFI_UNICAST);	/* SAFI */
        }

      /* Next hop */
      stream_putc(s, attr->mp_nexthop_len);
      stream_put(s, &attr->mp_nexthop_global, 16);
      if(attr->mp_nexthop_len == 32)
        stream_put(s, &attr->mp_nexthop_local, 16);

      if(!dump_small_mp_nlri)
        {
          /* SNPA */
          stream_putc(s, 0);

          /* Prefix */
          stream_put_prefix(s, prefix);
        }

      /* Set MP attribute length. */
      stream_putc_at (s, sizep, (stream_get_endp (s) - sizep) - 1);
    }
#endif /* HAVE_IPV6 */

  /* Return total size of attribute. */
  len = stream_get_endp (s) - cp - 2;
  stream_putw_at (s, cp, len);
}