bgp_attr.c

大名鼎鼎的路由器源码。程序分ZEBRA、OSPFRIP等3个包。程序框架采用一个路由协议一个进程的方式

	    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;

  /* AS path attribute extended length bit check. */
  if (aspath->length > 255)
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
      stream_putc (s, BGP_ATTR_AS_PATH);
      stream_putw (s, aspath->length);
    }
  else
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc(s, BGP_ATTR_AS_PATH);
      stream_putc (s, aspath->length);
    }
  stream_put (s, aspath->data, aspath->length);

  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))
    {
      stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_AGGREGATOR);
      stream_putc (s, 6);
      stream_putw (s, 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
	{
	  if (from)
	    stream_put_in_addr (s, &from->remote_id);
	  else
	    stream_put_in_addr (s, &attr->originator_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;
      unsigned long draftp = 0;

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

      /* In case of old draft BGP-4+. */
      if (peer->version == BGP_VERSION_MP_4_DRAFT_00)
	{
	  draftp = stream_get_putp (s);
	  stream_putw (s, 0);
	}
      
      /* Prefix write. */
      stream_put_prefix (s, p);

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

      /* In case of old draft BGP-4+. */
      if (peer->version == BGP_VERSION_MP_4_DRAFT_00)
	stream_putw_at (s, draftp, (stream_get_putp (s) - draftp) - 2);
    }
#endif /* HAVE_IPV6 */

  if (p->family == AF_INET && safi == SAFI_MULTICAST)
    {
      unsigned long sizep;
      unsigned long draftp = 0;

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

      /* In case of old draft BGP-4+. */
      if (peer->version == BGP_VERSION_MP_4_DRAFT_00)
	{
	  draftp = stream_get_putp (s);
	  stream_putw (s, 0);
	}
      
      /* Prefix write. */
      stream_put_prefix (s, p);

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

      /* In case of old draft BGP-4+. */
      if (peer->version == BGP_VERSION_MP_4_DRAFT_00)
	stream_putw_at (s, draftp, (stream_get_putp (s) - draftp) - 2);
    }

  if (p->family == AF_INET && safi == SAFI_MPLS_VPN)
    {
      unsigned long sizep;
      unsigned long draftp = 0;

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

      /* In case of old draft BGP-4+. */
      if (peer->version == BGP_VERSION_MP_4_DRAFT_00)
	{
	  draftp = stream_get_putp (s);
	  stream_putw (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_putp (s) - sizep) - 1);

      /* In case of old draft BGP-4+. */
      if (peer->version == BGP_VERSION_MP_4_DRAFT_00)
	stream_putw_at (s, draftp, (stream_get_putp (s) - draftp) - 2);
    }

  /* 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 (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);
    }

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

  /* Return total size of attribute. */
  return stream_get_putp (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_putp (s);

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

  attrlen_pnt = stream_get_putp (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_putp (s) - attrlen_pnt - 1;
  stream_putc_at (s, attrlen_pnt, size);

  return stream_get_putp (s) - cp;
}

/* Initialization of attribute. */
void
bgp_attr_init ()
{
  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)
{
  unsigned long cp;
  unsigned long len;
  struct aspath *aspath;

  /* Remember current pointer. */
  cp = stream_get_putp (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 (aspath->length > 255)
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
      stream_putc (s, BGP_ATTR_AS_PATH);
      stream_putw (s, aspath->length);
    }
  else
    {
      stream_putc (s, BGP_ATTR_FLAG_TRANS);
      stream_putc (s, BGP_ATTR_AS_PATH);
      stream_putc (s, aspath->length);
    }
  stream_put (s, aspath->data, aspath->length);

  /* Nexthop attribute. */
  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, 6);
      stream_putw (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);
    }

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