bgp_route.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

      break;

  /* AS path local-as loop check. */
  if (peer->change_local_as)
    {
      if (! CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND))
	aspath_loop_count = 1;

      if (aspath_loop_check (attr->aspath, peer->change_local_as) > aspath_loop_count) 
	{
	  reason = "as-path contains our own AS;";
	  goto filtered;
	}
    }

  /* AS path loop check. */
  if (aspath_loop_check (attr->aspath, bgp->as) > peer->allowas_in[afi][safi]
      || (CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION)
	  && aspath_loop_check(attr->aspath, bgp->confed_id)
	  > peer->allowas_in[afi][safi]))
    {
      reason = "as-path contains our own AS;";
      goto filtered;
    }

  /* Route reflector originator ID check.  */
  if (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_ORIGINATOR_ID)
      && IPV4_ADDR_SAME (&bgp->router_id, &attr->originator_id))
    {
      reason = "originator is us;";
      goto filtered;
    }

  /* Route reflector cluster ID check.  */
  if (bgp_cluster_filter (peer, attr))
    {
      reason = "reflected from the same cluster;";
      goto  filtered;
    }

  /* Apply incoming filter.  */
  if (bgp_input_filter (peer, p, attr, afi, safi) == FILTER_DENY)
    {
      reason = "filter;";
      goto filtered;
    }

  /* Apply incoming route-map. */
  new_attr = *attr;

  if (bgp_input_modifier (peer, p, &new_attr, afi, safi) == RMAP_DENY)
    {
      reason = "route-map;";
      goto filtered;
    }

  /* IPv4 unicast next hop check.  */
  if (afi == AFI_IP && safi == SAFI_UNICAST)
    {
      /* If the peer is EBGP and nexthop is not on connected route,
	 discard it.  */
      if (peer_sort (peer) == BGP_PEER_EBGP && peer->ttl == 1
	  && ! bgp_nexthop_check_ebgp (afi, &new_attr)
	  && ! CHECK_FLAG (peer->flags, PEER_FLAG_ENFORCE_MULTIHOP))
	{
	  reason = "non-connected next-hop;";
	  goto filtered;
	}

      /* Next hop must not be 0.0.0.0 nor Class E address.  Next hop
	 must not be my own address.  */
      if (bgp_nexthop_self (afi, &new_attr)
	  || new_attr.nexthop.s_addr == 0
	  || ntohl (new_attr.nexthop.s_addr) >= 0xe0000000)
	{
	  reason = "martian next-hop;";
	  goto filtered;
	}
    }

  attr_new = bgp_attr_intern (&new_attr);

  /* If the update is implicit withdraw. */
  if (ri)
    {
      ri->uptime = time (NULL);

      /* Same attribute comes in. */
      if (attrhash_cmp (ri->attr, attr_new))
	{
	  UNSET_FLAG (ri->flags, BGP_INFO_ATTR_CHANGED);

	  if (CHECK_FLAG (bgp->af_flags[afi][safi], BGP_CONFIG_DAMPENING)
	      && peer_sort (peer) == BGP_PEER_EBGP
	      && CHECK_FLAG (ri->flags, BGP_INFO_HISTORY))
	    {
	      if (BGP_DEBUG (update, UPDATE_IN))  
		  zlog (peer->log, LOG_INFO, "%s rcvd %s/%d",
		  peer->host,
		  inet_ntop(p->family, &p->u.prefix, buf, SU_ADDRSTRLEN),
		  p->prefixlen);

	      peer->pcount[afi][safi]++;
	      ret = bgp_damp_update (ri, rn, afi, safi);
	      if (ret != BGP_DAMP_SUPPRESSED)
		{
		  bgp_aggregate_increment (bgp, p, ri, afi, safi);
		  bgp_process (bgp, rn, afi, safi);
		}
	    }
	  else
	    {
	      if (BGP_DEBUG (update, UPDATE_IN))  
		zlog (peer->log, LOG_INFO,
		"%s rcvd %s/%d...duplicate ignored",
		peer->host,
		inet_ntop(p->family, &p->u.prefix, buf, SU_ADDRSTRLEN),
		p->prefixlen);
	    }

	  bgp_unlock_node (rn);
	  bgp_attr_unintern (attr_new);
	  return 0;
	}

      /* Received Logging. */
      if (BGP_DEBUG (update, UPDATE_IN))  
	zlog (peer->log, LOG_INFO, "%s rcvd %s/%d",
	      peer->host,
	      inet_ntop(p->family, &p->u.prefix, buf, SU_ADDRSTRLEN),
	      p->prefixlen);

      /* The attribute is changed. */
      SET_FLAG (ri->flags, BGP_INFO_ATTR_CHANGED);

      /* Update bgp route dampening information.  */
      if (CHECK_FLAG (bgp->af_flags[afi][safi], BGP_CONFIG_DAMPENING)
	  && peer_sort (peer) == BGP_PEER_EBGP)
	{
	  /* This is implicit withdraw so we should update dampening
	     information.  */
	  if (! CHECK_FLAG (ri->flags, BGP_INFO_HISTORY))
	    bgp_damp_withdraw (ri, rn, afi, safi, 1);  
	  else
	    peer->pcount[afi][safi]++;
	}
	
      bgp_aggregate_decrement (bgp, p, ri, afi, safi);

      /* Update to new attribute.  */
      bgp_attr_unintern (ri->attr);
      ri->attr = attr_new;

      /* Update MPLS tag.  */
      if (safi == SAFI_MPLS_VPN)
	memcpy (ri->tag, tag, 3);

      /* Update bgp route dampening information.  */
      if (CHECK_FLAG (bgp->af_flags[afi][safi], BGP_CONFIG_DAMPENING)
	  && peer_sort (peer) == BGP_PEER_EBGP)
	{
	  /* Now we do normal update dampening.  */
	  ret = bgp_damp_update (ri, rn, afi, safi);
	  if (ret == BGP_DAMP_SUPPRESSED)
	    {
	      bgp_unlock_node (rn);
	      return 0;
	    }
	}

      /* Nexthop reachability check. */
      if ((afi == AFI_IP || afi == AFI_IP6)
	  && safi == SAFI_UNICAST 
	  && (peer_sort (peer) == BGP_PEER_IBGP
	      || (peer_sort (peer) == BGP_PEER_EBGP && peer->ttl != 1)
	      || CHECK_FLAG (peer->flags, PEER_FLAG_ENFORCE_MULTIHOP)))
	{
	  if (bgp_nexthop_lookup (afi, peer, ri, NULL, NULL))
	    SET_FLAG (ri->flags, BGP_INFO_VALID);
	  else
	    UNSET_FLAG (ri->flags, BGP_INFO_VALID);
	}
      else
	SET_FLAG (ri->flags, BGP_INFO_VALID);

      /* Process change. */
      bgp_aggregate_increment (bgp, p, ri, afi, safi);

      bgp_process (bgp, rn, afi, safi);
      bgp_unlock_node (rn);
      return 0;
    }

  /* Received Logging. */
  if (BGP_DEBUG (update, UPDATE_IN))  
    {
      zlog (peer->log, LOG_INFO, "%s rcvd %s/%d",
	    peer->host,
	    inet_ntop(p->family, &p->u.prefix, buf, SU_ADDRSTRLEN),
	    p->prefixlen);
    }

  /* Increment prefix counter */
  peer->pcount[afi][safi]++;

  /* Make new BGP info. */
  new = bgp_info_new ();
  new->type = type;
  new->sub_type = sub_type;
  new->peer = peer;
  new->attr = attr_new;
  new->uptime = time (NULL);

  /* Update MPLS tag. */
  if (safi == SAFI_MPLS_VPN)
    memcpy (new->tag, tag, 3);

  /* Nexthop reachability check. */
  if ((afi == AFI_IP || afi == AFI_IP6)
      && safi == SAFI_UNICAST
      && (peer_sort (peer) == BGP_PEER_IBGP
	  || (peer_sort (peer) == BGP_PEER_EBGP && peer->ttl != 1)
	  || CHECK_FLAG (peer->flags, PEER_FLAG_ENFORCE_MULTIHOP)))
    {
      if (bgp_nexthop_lookup (afi, peer, new, NULL, NULL))
	SET_FLAG (new->flags, BGP_INFO_VALID);
      else
	UNSET_FLAG (new->flags, BGP_INFO_VALID);
    }
  else
    SET_FLAG (new->flags, BGP_INFO_VALID);

  /* Aggregate address increment. */
  bgp_aggregate_increment (bgp, p, new, afi, safi);
  
  /* Register new BGP information. */
  bgp_info_add (rn, new);

  /* If maximum prefix count is configured and current prefix
     count exeed it. */
  if (bgp_maximum_prefix_overflow (peer, afi, safi, 0))
    return -1;

  /* Process change. */
  bgp_process (bgp, rn, afi, safi);

  return 0;

  /* This BGP update is filtered.  Log the reason then update BGP
     entry.  */
 filtered:
  if (BGP_DEBUG (update, UPDATE_IN))
    zlog (peer->log, LOG_INFO,
	  "%s rcvd UPDATE about %s/%d -- DENIED due to: %s",
	  peer->host,
	  inet_ntop (p->family, &p->u.prefix, buf, SU_ADDRSTRLEN),
	  p->prefixlen, reason);

  if (ri)
    bgp_rib_withdraw (rn, ri, peer, afi, safi, 1);

  bgp_unlock_node (rn);

  return 0;
}

int
bgp_withdraw (struct peer *peer, struct prefix *p, struct attr *attr, 
	     int afi, int safi, int type, int sub_type, struct prefix_rd *prd,
	      u_char *tag)
{
  struct bgp *bgp;
  char buf[SU_ADDRSTRLEN];
  struct bgp_node *rn;
  struct bgp_info *ri;

  bgp = peer->bgp;

  /* Logging. */
  if (BGP_DEBUG (update, UPDATE_IN))  
    zlog (peer->log, LOG_INFO, "%s rcvd UPDATE about %s/%d -- withdrawn",
	  peer->host,
	  inet_ntop(p->family, &p->u.prefix, buf, SU_ADDRSTRLEN),
	  p->prefixlen);

  /* Lookup node. */
  rn = bgp_afi_node_get (bgp, afi, safi, p, prd);

  /* If peer is soft reconfiguration enabled.  Record input packet for
     further calculation. */
  if (CHECK_FLAG (peer->af_flags[afi][safi], PEER_FLAG_SOFT_RECONFIG)
      && peer != bgp->peer_self)
    bgp_adj_in_unset (rn, peer);

  /* Lookup withdrawn route. */
  for (ri = rn->info; ri; ri = ri->next)
    if (ri->peer == peer && ri->type == type && ri->sub_type == sub_type)
      break;

  /* Withdraw specified route from routing table. */
  if (ri && ! CHECK_FLAG (ri->flags, BGP_INFO_HISTORY))
    bgp_rib_withdraw (rn, ri, peer, afi, safi, 0);
  else if (BGP_DEBUG (update, UPDATE_IN))
    zlog (peer->log, LOG_INFO, 
	  "%s Can't find the route %s/%d", peer->host,
	  inet_ntop (p->family, &p->u.prefix, buf, SU_ADDRSTRLEN),
	  p->prefixlen);

  /* Unlock bgp_node_get() lock. */
  bgp_unlock_node (rn);

  return 0;
}

void
bgp_default_originate (struct peer *peer, afi_t afi, safi_t safi, int withdraw)
{
  struct bgp *bgp;
  struct attr attr;
  struct aspath *aspath;
  struct prefix p;
  struct bgp_info binfo;
  struct peer *from;
  int ret = RMAP_DENYMATCH;

  bgp = peer->bgp;
  from = bgp->peer_self;

  bgp_attr_default_set (&attr, BGP_ORIGIN_IGP);
  aspath = attr.aspath;
  attr.local_pref = bgp->default_local_pref;
  memcpy (&attr.nexthop, &peer->nexthop.v4, IPV4_MAX_BYTELEN);

  if (afi == AFI_IP)
    str2prefix ("0.0.0.0/0", &p);
#ifdef HAVE_IPV6
  else if (afi == AFI_IP6)
    {
      str2prefix ("::/0", &p);

      /* IPv6 global nexthop must be included. */
      memcpy (&attr.mp_nexthop_global, &peer->nexthop.v6_global, 
	      IPV6_MAX_BYTELEN);
	      attr.mp_nexthop_len = 16;
 
      /* If the peer is on shared nextwork and we have link-local
	 nexthop set it. */
      if (peer->shared_network 
	  && !IN6_IS_ADDR_UNSPECIFIED (&peer->nexthop.v6_local))
	{
	  memcpy (&attr.mp_nexthop_local, &peer->nexthop.v6_local, 
		  IPV6_MAX_BYTELEN);
	  attr.mp_nexthop_len = 32;
	}
    }
#endif /* HAVE_IPV6 */
  else
    return;

  if (peer->default_rmap[afi][safi].name)
    {
      binfo.peer = bgp->peer_self;
      binfo.attr = &attr;

      ret = route_map_apply (peer->default_rmap[afi][safi].map, &p,
			     RMAP_BGP, &binfo);

      if (ret == RMAP_DENYMATCH)
	{
	  bgp_attr_flush (&attr);
	  withdraw = 1;
	}
    }

  if (withdraw)
    {
      if (CHECK_FLAG (peer->af_sflags[afi][safi], PEER_STATUS_DEFAULT_ORIGINATE))
	bgp_default_withdraw_send (peer, afi, safi);
      UNSET_FLAG (peer->af_sflags[afi][safi], PEER_STATUS_DEFAULT_ORIGINATE);
    }
  else
    {
      SET_FLAG (peer->af_sflags[afi][safi], PEER_STATUS_DEFAULT_ORIGINATE);
      bgp_default_update_send (peer, &attr, afi, safi, from);
    }

  aspath_unintern (aspath);
}

static void
bgp_announce_table (struct peer *peer, afi_t afi, safi_t safi,
		    struct bgp_table *table)
{
  struct bgp_node *rn;
  struct bgp_info *ri;
  struct attr attr;

  if (! table)
    table = peer->bgp->rib[afi][safi];

  if (safi != SAFI_MPLS_VPN
      && CHECK_FLAG (peer->af_flags[afi][safi], PEER_FLAG_DEFAULT_ORIGINATE))
    bgp_default_originate (peer, afi, safi, 0);

  for (rn = bgp_table_top (table); rn; rn = bgp_route_next(rn))
    for (ri = rn->info; ri; ri = ri->next)
      if (CHECK_FLAG (ri->flags, BGP_INFO_SELECTED) && ri->peer != peer)
	{
	  if (bgp_announce_check (ri, peer, &rn->p, &attr, afi, safi))
	    bgp_adj_out_set (rn, peer, &rn->p, &attr, afi, safi, ri);
	  else
	    bgp_adj_out_unset (rn, peer, &rn->p, afi, safi);
	}
}

void
bgp_announce_route (struct peer *peer, afi_t afi, safi_t safi)
{
  struct bgp_node *rn;
  struct bgp_table *table;

  if (peer->status != Established)
    return;

  if (! peer->afc_nego[afi][safi])
    return;

  /* First update is deferred until ORF or ROUTE-REFRESH is received */
  if (CHECK_FLAG (peer->af_sflags[afi][safi], PEER_STATUS_ORF_WAIT_REFRESH))
    return;

  if (safi != SAFI_MPLS_VPN)
    bgp_announce_table (peer, afi, safi, NULL);
  else
    for (rn = bgp_table_top (peer->bgp->rib[afi][safi]); rn;
	 rn = bgp_route_next(rn))
      if ((table = (rn->info)) != NULL)
	bgp_announce_table (peer, afi, safi, table);
}

void
bgp_announce_route_all (struct peer *peer)
{
  afi_t afi;
  safi_t safi;
  
  for (afi = AFI_IP; afi < AFI_MAX; afi++)
    for (safi = SAFI_UNICAST; safi < SAFI_MAX; safi++)
      bgp_announce_route (peer, afi, safi);
}

static void
bgp_soft_reconfig_table (struct peer *peer, afi_t afi, safi_t safi,
			 struct bgp_table *table)
{
  int ret;
  struct bgp_node *rn;
  struct bgp_adj_in *ain;

  if (! table)
    table = peer->bgp->rib[afi][safi];

  for (rn = bgp_table_top (table); rn; rn = bgp_route_next (rn))
    for (ain = rn->adj_in; ain; ain = ain->next)
      {
	if (ain->peer == peer)
	  {
	    ret = bgp_update (peer, &rn->p, ain->attr, afi, safi,
			      ZEBRA_ROUTE_BGP, BGP_ROUTE_NORMAL,
			      NULL, NULL, 1);
	    if (ret < 0)
	      {
		bgp_unlock_node (rn);
		return;
	      }
	    continue;
	  }
      }
}

void
bgp_soft_reconfig_in (struct peer *peer, afi_t afi, safi_t safi)
{
  struct bgp_node *rn;
  struct bgp_table *table;

  if (peer->status != Established)
    return;

  if (safi != SAFI_MPLS_VPN)
    bgp_soft_reconfig_table (peer, afi, safi, NULL);
  else
    for (rn = bgp_table_top (peer->bgp->rib[afi][safi]); rn;
	 rn = bgp_route_next (rn))
      if ((table = rn->info) != NULL)
	bgp_soft_reconfig_table (peer, afi, safi, table);
}

static void
bgp_clear_route_table (struct peer *peer, afi_t afi, safi_t safi,
		       struct bgp_table *table)
{
  struct bgp_node *rn;
  struct bgp_adj_in *ain;