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

#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. */
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. */
int
bgp_attr_aspath (struct peer *peer, bgp_size_t length, 
		 struct attr *attr, u_char flag, u_char *startp)
{
  struct bgp *bgp;
  struct aspath *aspath;
  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;
    }

  /* In case of IBGP, length will be zero. */
  attr->aspath = aspath_parse (stream_pnt (peer->ibuf), length);
  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;
    }

  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);
    }

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

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

  return 0;
}

/* Nexthop attribute. */
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. */
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. */
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 (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. */
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 */
int
bgp_attr_aggregator (struct peer *peer, bgp_size_t length,
		     struct attr *attr, u_char flag)
{
  if (length != 6)
    {
      zlog (peer->log, LOG_ERR, "Aggregator length is not 6 [%d]", length);

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

/* Community attribute. */
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 (stream_pnt (peer->ibuf), length);
      stream_forward (peer->ibuf, length);
    }

  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES);

  return 0;
}

/* Originator ID attribute. */
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. */
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 (stream_pnt (peer->ibuf), length);

  stream_forward (peer->ibuf, length);;

  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_CLUSTER_LIST);

  return 0;
}

/* Multiprotocol reachability information parse. */
int
bgp_mp_reach_parse (struct peer *peer, bgp_size_t length, struct attr *attr,
		    struct bgp_nlri *mp_update)
{