bird/nest/rt-table.c

/*
 *	BIRD -- Routing Tables
 *
 *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

/**
 * DOC: Routing tables
 *
 * Routing tables are probably the most important structures BIRD uses. They
 * hold all the information about known networks, the associated routes and
 * their attributes.
 *
 * There are multiple routing tables (a primary one together with any
 * number of secondary ones if requested by the configuration). Each table
 * is basically a FIB containing entries describing the individual
 * destination networks. For each network (represented by structure &net),
 * there is a one-way linked list of route entries (&rte), the first entry
 * on the list being the best one (i.e., the one we currently use
 * for routing), the order of the other ones is undetermined.
 *
 * The &rte contains information specific to the route (preference, protocol
 * metrics, time of last modification etc.) and a pointer to a &rta structure
 * (see the route attribute module for a precise explanation) holding the
 * remaining route attributes which are expected to be shared by multiple
 * routes in order to conserve memory.
 */

#undef LOCAL_DEBUG

#include "nest/bird.h"
#include "nest/route.h"
#include "nest/protocol.h"
#include "nest/cli.h"
#include "nest/iface.h"
#include "lib/resource.h"
#include "lib/event.h"
#include "lib/string.h"
#include "conf/conf.h"
#include "filter/filter.h"
#include "lib/string.h"
#include "lib/alloca.h"

pool *rt_table_pool;

static slab *rte_slab;
static linpool *rte_update_pool;

static list routing_tables;

static void rt_format_via(rte *e, byte *via);
static void rt_free_hostcache(rtable *tab);
static void rt_notify_hostcache(rtable *tab, net *net);
static void rt_update_hostcache(rtable *tab);
static void rt_next_hop_update(rtable *tab);

static inline void rt_schedule_gc(rtable *tab);

/* Like fib_route(), but skips empty net entries */
static net *
net_route(rtable *tab, ip_addr a, int len)
{
  ip_addr a0;
  net *n;

  while (len >= 0)
    {
      a0 = ipa_and(a, ipa_mkmask(len));
      n = fib_find(&tab->fib, &a0, len);
      if (n && n->routes)
	return n;
      len--;
    }
  return NULL;
}

static void
rte_init(struct fib_node *N)
{
  net *n = (net *) N;

  N->flags = 0;
  n->routes = NULL;
}

/**
 * rte_find - find a route
 * @net: network node
 * @p: protocol
 *
 * The rte_find() function returns a route for destination @net
 * which belongs has been defined by protocol @p.
 */
rte *
rte_find(net *net, struct proto *p)
{
  rte *e = net->routes;

  while (e && e->attrs->proto != p)
    e = e->next;
  return e;
}

/**
 * rte_get_temp - get a temporary &rte
 * @a: attributes to assign to the new route (a &rta; in case it's
 * un-cached, rte_update() will create a cached copy automatically)
 *
 * Create a temporary &rte and bind it with the attributes @a.
 * Also set route preference to the default preference set for
 * the protocol.
 */
rte *
rte_get_temp(rta *a)
{
  rte *e = sl_alloc(rte_slab);

  e->attrs = a;
  e->flags = 0;
  e->pref = a->proto->preference;
  return e;
}

rte *
rte_do_cow(rte *r)
{
  rte *e = sl_alloc(rte_slab);

  memcpy(e, r, sizeof(rte));
  e->attrs = rta_clone(r->attrs);
  e->flags = 0;
  return e;
}

static int				/* Actually better or at least as good as */
rte_better(rte *new, rte *old)
{
  int (*better)(rte *, rte *);

  if (!old)
    return 1;
  if (new->pref > old->pref)
    return 1;
  if (new->pref < old->pref)
    return 0;
  if (new->attrs->proto->proto != old->attrs->proto->proto)
    {
      /*
       *  If the user has configured protocol preferences, so that two different protocols
       *  have the same preference, try to break the tie by comparing addresses. Not too
       *  useful, but keeps the ordering of routes unambiguous.
       */
      return new->attrs->proto->proto > old->attrs->proto->proto;
    }
  if (better = new->attrs->proto->rte_better)
    return better(new, old);
  return 0;
}

static void
rte_trace(struct proto *p, rte *e, int dir, char *msg)
{
  byte via[STD_ADDRESS_P_LENGTH+32];

  rt_format_via(e, via);
  log(L_TRACE "%s %c %s %I/%d %s", p->name, dir, msg, e->net->n.prefix, e->net->n.pxlen, via);
}

static inline void
rte_trace_in(unsigned int flag, struct proto *p, rte *e, char *msg)
{
  if (p->debug & flag)
    rte_trace(p, e, '>', msg);
}

static inline void
rte_trace_out(unsigned int flag, struct proto *p, rte *e, char *msg)
{
  if (p->debug & flag)
    rte_trace(p, e, '<', msg);
}

static rte *
export_filter(struct announce_hook *ah, rte *rt0, rte **rt_free, ea_list **tmpa, int silent)
{
  struct proto *p = ah->proto;
  struct filter *filter = ah->out_filter;
  struct proto_stats *stats = ah->stats;
  ea_list *tmpb = NULL;
  rte *rt;
  int v;

  rt = rt0;
  *rt_free = NULL;

  /* If called does not care for eattrs, we prepare one internally */
  if (!tmpa)
    {
      struct proto *src = rt->attrs->proto;
      tmpb = src->make_tmp_attrs ? src->make_tmp_attrs(rt, rte_update_pool) : NULL;
      tmpa = &tmpb;
    }

  v = p->import_control ? p->import_control(p, &rt, tmpa, rte_update_pool) : 0;
  if (v < 0)
    {
      if (silent)
	goto reject;

      stats->exp_updates_rejected++;
      rte_trace_out(D_FILTERS, p, rt, "rejected by protocol");
      goto reject;
    }
  if (v > 0)
    {
      if (!silent)
	rte_trace_out(D_FILTERS, p, rt, "forced accept by protocol");
      goto accept;
    }

  v = filter && ((filter == FILTER_REJECT) ||
		 (f_run(filter, &rt, tmpa, rte_update_pool, FF_FORCE_TMPATTR) > F_ACCEPT));
  if (v)
    {
      if (silent)
	goto reject;

      stats->exp_updates_filtered++;
      rte_trace_out(D_FILTERS, p, rt, "filtered out");
      goto reject;
    }

 accept:
  if (rt != rt0)
    *rt_free = rt;
  return rt;

 reject:
  /* Discard temporary rte */
  if (rt != rt0)
    rte_free(rt);
  return NULL;
}

static void
do_rt_notify(struct announce_hook *ah, net *net, rte *new, rte *old, ea_list *tmpa, int refeed)
{
  struct proto *p = ah->proto;
  struct proto_stats *stats = ah->stats;

  if (new)
    stats->exp_updates_accepted++;
  else
    stats->exp_withdraws_accepted++;

  /* Hack: We do not decrease exp_routes during refeed, we instead
     reset exp_routes at the start of refeed. */
  if (new)
    stats->exp_routes++;
  if (old && !refeed)
    stats->exp_routes--;

  if (p->debug & D_ROUTES)
    {
      if (new && old)
	rte_trace_out(D_ROUTES, p, new, "replaced");
      else if (new)
	rte_trace_out(D_ROUTES, p, new, "added");
      else if (old)
	rte_trace_out(D_ROUTES, p, old, "removed");
    }
  if (!new)
    p->rt_notify(p, ah->table, net, NULL, old, NULL);
  else if (tmpa)
    {
      ea_list *t = tmpa;
      while (t->next)
	t = t->next;
      t->next = new->attrs->eattrs;
      p->rt_notify(p, ah->table, net, new, old, tmpa);
      t->next = NULL;
    }
  else
    p->rt_notify(p, ah->table, net, new, old, new->attrs->eattrs);

}


static void
rt_notify_basic(struct announce_hook *ah, net *net, rte *new, rte *old, ea_list *tmpa, int refeed)
{
  // struct proto *p = ah->proto;
  struct proto_stats *stats = ah->stats;

  rte *new_free = NULL;
  rte *old_free = NULL;

  if (new)
    stats->exp_updates_received++;
  else
    stats->exp_withdraws_received++;

  /*
   * This is a tricky part - we don't know whether route 'old' was
   * exported to protocol 'p' or was filtered by the export filter.
   * We try to run the export filter to know this to have a correct
   * value in 'old' argument of rte_update (and proper filter value)
   *
   * FIXME - this is broken because 'configure soft' may change
   * filters but keep routes. Refeed is expected to be called after
   * change of the filters and with old == new, therefore we do not
   * even try to run the filter on an old route, This may lead to 
   * 'spurious withdraws' but ensure that there are no 'missing
   * withdraws'.
   *
   * This is not completely safe as there is a window between
   * reconfiguration and the end of refeed - if a newly filtered
   * route disappears during this period, proper withdraw is not
   * sent (because old would be also filtered) and the route is
   * not refeeded (because it disappeared before that).
   */

  if (new)
    new = export_filter(ah, new, &new_free, &tmpa, 0);

  if (old && !refeed)
    old = export_filter(ah, old, &old_free, NULL, 1);

  /* FIXME - This is broken because of incorrect 'old' value (see above) */
  if (!new && !old)
    return;

  do_rt_notify(ah, net, new, old, tmpa, refeed);

  /* Discard temporary rte's */
  if (new_free)
    rte_free(new_free);
  if (old_free)
    rte_free(old_free);
}

static void
rt_notify_accepted(struct announce_hook *ah, net *net, rte *new_changed, rte *old_changed, rte *before_old,
		   ea_list *tmpa, int feed)
{
  // struct proto *p = ah->proto;
  struct proto_stats *stats = ah->stats;

  rte *new_best = NULL;
  rte *old_best = NULL;
  rte *new_free = NULL;
  rte *old_free = NULL;
  rte *r;

  /* Used to track whethe we met old_changed position. If it is NULL
     it was the first and met it implicitly before current best route. */
  int old_meet = (old_changed && !before_old) ? 1 : 0;

  if (new_changed)
    stats->exp_updates_received++;
  else
    stats->exp_withdraws_received++;

  /* First, find the new_best route - first accepted by filters */
  for (r=net->routes; r; r=r->next)
    {
      if (new_best = export_filter(ah, r, &new_free, &tmpa, 0))
	break;

      /* Note if we walked around the position of old_changed route */
      if (r == before_old)
	old_meet = 1;
    }

  /* 
   * Second, handle the feed case. That means we do not care for
   * old_best. It is NULL for feed, and the new_best for refeed. 
   * For refeed, there is a hack similar to one in rt_notify_basic()
   * to ensure withdraws in case of changed filters
   */
  if (feed)
    {
      if (feed == 2)	/* refeed */
	old_best = new_best ? new_best : net->routes;
      else
	old_best = NULL;

      if (!new_best && !old_best)
	return;

      goto found;
    }

  /*
   * Now, we find the old_best route. Generally, it is the same as the
   * new_best, unless new_best is the same as new_changed or
   * old_changed is accepted before new_best.
   *
   * There are four cases:
   *
   * - We would find and accept old_changed before new_best, therefore
   *   old_changed is old_best. In remaining cases we suppose this
   *   is not true.
   *
   * - We found no new_best, therefore there is also no old_best and
   *   we ignore this withdraw.
   *
   * - We found new_best different than new_changed, therefore
   *   old_best is the same as new_best and we ignore this update.
   *
   * - We found new_best the same as new_changed, therefore it cannot
   *   be old_best and we have to continue search for old_best.
   */

  /* First case */
  if (old_meet)
    if (old_best = export_filter(ah, old_changed, &old_free, NULL, 1))
      goto found;

  /* Second case */
  if (!new_best)
    return;

  /* Third case, we use r insead of new_best, because export_filter() could change it */
  if (r != new_changed)
    {
      if (new_free)
	rte_free(new_free);
      return;
    }

  /* Fourth case */
  for (; r; r=r->next)
    {
      if (old_best = export_filter(ah, r, &old_free, NULL, 1))
	goto found;

      if (r == before_old)
	if (old_best = export_filter(ah, old_changed, &old_free, NULL, 1))
	  goto found;
    }

  /* Implicitly, old_best is NULL and new_best is non-NULL */

 found:
  do_rt_notify(ah, net, new_best, old_best, tmpa, (feed == 2));

  /* Discard temporary rte's */
  if (new_free)
    rte_free(new_free);
  if (old_free)
    rte_free(old_free);
}

/**
 * rte_announce - announce a routing table change
 * @tab: table the route has been added to
 * @type: type of route announcement (RA_OPTIMAL or RA_ANY)
 * @net: network in question
 * @new: the new route to be announced
 * @old: the previous route for the same network
 * @tmpa: a list of temporary attributes belonging to the new route
 *
 * This function gets a routing table update and announces it
 * to all protocols that acccepts given type of route announcement
 * and are connected to the same table by their announcement hooks.
 *
 * Route announcement of type RA_OPTIMAL si generated when optimal
 * route (in routing table @tab) changes. In that case @old stores the
 * old optimal route.
 *
 * Route announcement of type RA_ANY si generated when any route (in
 * routing table @tab) changes In that case @old stores the old route
 * from the same protocol.
 *
 * For each appropriate protocol, we first call its import_control()
 * hook which performs basic checks on the route (each protocol has a
 * right to veto or force accept of the route before any filter is
 * asked) and adds default values of attributes specific to the new
 * protocol (metrics, tags etc.).  Then it consults the protocol's
 * export filter and if it accepts the route, the rt_notify() hook of
 * the protocol gets called.
 */
static void
rte_announce(rtable *tab, unsigned type, net *net, rte *new, rte *old, rte *before_old, ea_list *tmpa)
{
  struct announce_hook *a;

  if (type == RA_OPTIMAL)
    {
      if (new)
	new->attrs->proto->stats.pref_routes++;
      if (old)
	old->attrs->proto->stats.pref_routes--;

      if (tab->hostcache)
	rt_notify_hostcache(tab, net);
    }

  WALK_LIST(a, tab->hooks)
    {
      ASSERT(a->proto->core_state == FS_HAPPY || a->proto->core_state == FS_FEEDING);
      if (a->proto->accept_ra_types == type)
	if (type == RA_ACCEPTED)
	  rt_notify_accepted(a, net, new, old, before_old, tmpa, 0);
	else
	  rt_notify_basic(a, net, new, old, tmpa, 0);
    }
}

static inline int
rte_validate(rte *e)
{
  int c;
  net *n = e->net;

  if ((n->n.pxlen > BITS_PER_IP_ADDRESS) || !ip_is_prefix(n->n.prefix,n->n.pxlen))
    {
      log(L_WARN "Ignoring bogus prefix %I/%d received via %s",
	  n->n.prefix, n->n.pxlen, e->sender->proto->name);
      return 0;
    }

  c = ipa_classify_net(n->n.prefix);
  if ((c < 0) || !(c & IADDR_HOST) || ((c & IADDR_SCOPE_MASK) <= SCOPE_LINK))
    {
      log(L_WARN "Ignoring bogus route %I/%d received via %s",
	  n->n.prefix, n->n.pxlen, e->sender->proto->name);
      return 0;
    }

  return 1;
}

/**
 * rte_free - delete a &rte
 * @e: &rte to be deleted
 *
 * rte_free() deletes the given &rte from the routing table it's linked to.
 */
void
rte_free(rte *e)
{
  if (e->attrs->aflags & RTAF_CACHED)
    rta_free(e->attrs);
  sl_free(rte_slab, e);
}

static inline void
rte_free_quick(rte *e)
{
  rta_free(e->attrs);
  sl_free(rte_slab, e);
}

static int
rte_same(rte *x, rte *y)
{
  return
    x->attrs == y->attrs &&
    x->flags == y->flags &&
    x->pflags == y->pflags &&
    x->pref == y->pref &&
    (!x->attrs->proto->rte_same || x->attrs->proto->rte_same(x, y));
}

static void
rte_recalculate(struct announce_hook *ah, net *net, rte *new, ea_list *tmpa, struct proto *src)
{
  struct proto *p = ah->proto;
  struct rtable *table = ah->table;
  struct proto_stats *stats = ah->stats;
  rte *before_old = NULL;
  rte *old_best = net->routes;
  rte *old = NULL;
  rte **k;

  k = &net->routes;			/* Find and remove original route from the same protocol */
  while (old = *k)
    {
      if (old->attrs->proto == src)
	{
	  /* If there is the same route in the routing table but from
	   * a different sender, then there are two paths from the
	   * source protocol to this routing table through transparent
	   * pipes, which is not allowed.
	   *
	   * We log that and ignore the route. If it is withdraw, we
	   * ignore it completely (there might be 'spurious withdraws',
	   * see FIXME in do_rte_announce())
	   */
	  if (old->sender->proto != p)
	    {
	      if (new)
		{
		  log(L_ERR "Pipe collision detected when sending %I/%d to table %s",
		      net->n.prefix, net->n.pxlen, table->name);
		  rte_free_quick(new);
		}
	      return;
	    }

	  if (new && rte_same(old, new))
	    {
	      /* No changes, ignore the new route */
	      stats->imp_updates_ignored++;
	      rte_trace_in(D_ROUTES, p, new, "ignored");
	      rte_free_quick(new);
#ifdef CONFIG_RIP
	      /* lastmod is used internally by RIP as the last time
		 when the route was received. */
	      if (src->proto == &proto_rip)
		old->lastmod = now;
#endif
	      return;
	    }
	  *k = old->next;
	  break;
	}
      k = &old->next;
      before_old = old;
    }

  if (!old)
    before_old = NULL;

  if (!old && !new)
    {
      stats->imp_withdraws_ignored++;
      return;
    }

  if (new)
    stats->imp_updates_accepted++;
  else
    stats->imp_withdraws_accepted++;

  if (new)
    stats->imp_routes++;
  if (old)
    stats->imp_routes--;

  if (new)
    {
      for (k=&net->routes; *k; k=&(*k)->next)
	if (rte_better(new, *k))
	  break;

      new->lastmod = now;
      new->next = *k;
      *k = new;

      rte_trace_in(D_ROUTES, p, new, net->routes == new ? "added [best]" : "added");
    }

  /* Log the route removal */
  if (!new && (p->debug & D_ROUTES))
    {
      if (old != old_best)
	rte_trace_in(D_ROUTES, p, old, "removed");
      else if (net->routes)
	rte_trace_in(D_ROUTES, p, old, "removed [replaced]");
      else
	rte_trace_in(D_ROUTES, p, old, "removed [sole]");
    }

  rte_announce(table, RA_ANY, net, new, old, NULL, tmpa);
  rte_announce(table, RA_OPTIMAL, net, net->routes, old_best, NULL, tmpa);
  rte_announce(table, RA_ACCEPTED, net, new, old, before_old, tmpa);

  if (!net->routes &&
      (table->gc_counter++ >= table->config->gc_max_ops) &&
      (table->gc_time + table->config->gc_min_time <= now))
    rt_schedule_gc(table);

  if (old)
    {
      if (p->rte_remove)
	p->rte_remove(net, old);
      rte_free_quick(old);
    }
  if (new)
    {
      if (p->rte_insert)
	p->rte_insert(net, new);
    }
}

static int rte_update_nest_cnt;		/* Nesting counter to allow recursive updates */

static inline void
rte_update_lock(void)
{
  rte_update_nest_cnt++;
}

static inline void
rte_update_unlock(void)
{
  if (!--rte_update_nest_cnt)
    lp_flush(rte_update_pool);
}

/**
 * rte_update - enter a new update to a routing table
 * @table: table to be updated
 * @ah: pointer to table announce hook
 * @net: network node
 * @p: protocol submitting the update
 * @src: protocol originating the update
 * @new: a &rte representing the new route or %NULL for route removal.
 *
 * This function is called by the routing protocols whenever they discover
 * a new route or wish to update/remove an existing route. The right announcement
 * sequence is to build route attributes first (either un-cached with @aflags set
 * to zero or a cached one using rta_lookup(); in this case please note that
 * you need to increase the use count of the attributes yourself by calling
 * rta_clone()), call rte_get_temp() to obtain a temporary &rte, fill in all
 * the appropriate data and finally submit the new &rte by calling rte_update().
 *
 * @src specifies the protocol that originally created the route and the meaning
 * of protocol-dependent data of @new. If @new is not %NULL, @src have to be the
 * same value as @new->attrs->proto. @p specifies the protocol that called
 * rte_update(). In most cases it is the same protocol as @src. rte_update()
 * stores @p in @new->sender;
 *
 * When rte_update() gets any route, it automatically validates it (checks,
 * whether the network and next hop address are valid IP addresses and also
 * whether a normal routing protocol doesn't try to smuggle a host or link
 * scope route to the table), converts all protocol dependent attributes stored
 * in the &rte to temporary extended attributes, consults import filters of the
 * protocol to see if the route should be accepted and/or its attributes modified,
 * stores the temporary attributes back to the &rte.
 *
 * Now, having a "public" version of the route, we
 * automatically find any old route defined by the protocol @src
 * for network @n, replace it by the new one (or removing it if @new is %NULL),
 * recalculate the optimal route for this destination and finally broadcast
 * the change (if any) to all routing protocols by calling rte_announce().
 *
 * All memory used for attribute lists and other temporary allocations is taken
 * from a special linear pool @rte_update_pool and freed when rte_update()
 * finishes.
 */

void
rte_update2(struct announce_hook *ah, net *net, rte *new, struct proto *src)
{
  struct proto *p = ah->proto;
  struct proto_stats *stats = ah->stats;
  struct filter *filter = ah->in_filter;
  ea_list *tmpa = NULL;

  rte_update_lock();
  if (new)
    {
      new->sender = ah;

      stats->imp_updates_received++;
      if (!rte_validate(new))
	{
	  rte_trace_in(D_FILTERS, p, new, "invalid");
	  stats->imp_updates_invalid++;
	  goto drop;
	}
      if (filter == FILTER_REJECT)
	{
	  stats->imp_updates_filtered++;
	  rte_trace_in(D_FILTERS, p, new, "filtered out");
	  goto drop;
	}
      if (src->make_tmp_attrs)
	tmpa = src->make_tmp_attrs(new, rte_update_pool);
      if (filter)
	{
	  ea_list *old_tmpa = tmpa;
	  int fr = f_run(filter, &new, &tmpa, rte_update_pool, 0);
	  if (fr > F_ACCEPT)
	    {
	      stats->imp_updates_filtered++;
	      rte_trace_in(D_FILTERS, p, new, "filtered out");
	      goto drop;
	    }
	  if (tmpa != old_tmpa && src->store_tmp_attrs)
	    src->store_tmp_attrs(new, tmpa);
	}
      if (!(new->attrs->aflags & RTAF_CACHED)) /* Need to copy attributes */
	new->attrs = rta_lookup(new->attrs);
      new->flags |= REF_COW;
    }
  else
    stats->imp_withdraws_received++;

  rte_recalculate(ah, net, new, tmpa, src);
  rte_update_unlock();
  return;

drop:
  rte_free(new);
  rte_recalculate(ah, net, NULL, NULL, src);
  rte_update_unlock();
}

/* Independent call to rte_announce(), used from next hop
   recalculation, outside of rte_update(). new must be non-NULL */
static inline void 
rte_announce_i(rtable *tab, unsigned type, net *n, rte *new, rte *old)
{
  struct proto *src;
  ea_list *tmpa;

  rte_update_lock();
  src = new->attrs->proto;
  tmpa = src->make_tmp_attrs ? src->make_tmp_attrs(new, rte_update_pool) : NULL;
  rte_announce(tab, type, n, new, old, NULL, tmpa);
  rte_update_unlock();
}

void
rte_discard(rtable *t, rte *old)	/* Non-filtered route deletion, used during garbage collection */
{
  rte_update_lock();
  rte_recalculate(old->sender, old->net, NULL, NULL, old->attrs->proto);
  rte_update_unlock();
}

/**
 * rte_dump - dump a route
 * @e: &rte to be dumped
 *
 * This functions dumps contents of a &rte to debug output.
 */
void
rte_dump(rte *e)
{
  net *n = e->net;
  if (n)
    debug("%-1I/%2d ", n->n.prefix, n->n.pxlen);
  else
    debug("??? ");
  debug("KF=%02x PF=%02x pref=%d lm=%d ", n->n.flags, e->pflags, e->pref, now-e->lastmod);
  rta_dump(e->attrs);
  if (e->attrs->proto->proto->dump_attrs)
    e->attrs->proto->proto->dump_attrs(e);
  debug("\n");
}

/**
 * rt_dump - dump a routing table
 * @t: routing table to be dumped
 *
 * This function dumps contents of a given routing table to debug output.
 */
void
rt_dump(rtable *t)
{
  rte *e;
  net *n;
  struct announce_hook *a;

  debug("Dump of routing table <%s>\n", t->name);
#ifdef DEBUGGING
  fib_check(&t->fib);
#endif
  FIB_WALK(&t->fib, fn)
    {
      n = (net *) fn;
      for(e=n->routes; e; e=e->next)
	rte_dump(e);
    }
  FIB_WALK_END;
  WALK_LIST(a, t->hooks)
    debug("\tAnnounces routes to protocol %s\n", a->proto->name);
  debug("\n");
}

/**
 * rt_dump_all - dump all routing tables
 *
 * This function dumps contents of all routing tables to debug output.
 */
void
rt_dump_all(void)
{
  rtable *t;

  WALK_LIST(t, routing_tables)
    rt_dump(t);
}

static inline void
rt_schedule_gc(rtable *tab)
{
  if (tab->gc_scheduled)
    return;

  tab->gc_scheduled = 1;
  ev_schedule(tab->rt_event);
}

static inline void
rt_schedule_hcu(rtable *tab)
{
  if (tab->hcu_scheduled)
    return;

  tab->hcu_scheduled = 1;
  ev_schedule(tab->rt_event);
}

static inline void
rt_schedule_nhu(rtable *tab)
{
  if (tab->nhu_state == 0)
    ev_schedule(tab->rt_event);

  /* state change 0->1, 2->3 */
  tab->nhu_state |= 1;
}

static void
rt_prune_nets(rtable *tab)
{
  struct fib_iterator fit;
  int ncnt = 0, ndel = 0;

#ifdef DEBUGGING
  fib_check(&tab->fib);
#endif

  FIB_ITERATE_INIT(&fit, &tab->fib);
again:
  FIB_ITERATE_START(&tab->fib, &fit, f)
    {
      net *n = (net *) f;
      ncnt++;
      if (!n->routes)		/* Orphaned FIB entry */
	{
	  FIB_ITERATE_PUT(&fit, f);
	  fib_delete(&tab->fib, f);
	  ndel++;
	  goto again;
	}
    }
  FIB_ITERATE_END(f);
  DBG("Pruned %d of %d networks\n", ndel, ncnt);

  tab->gc_counter = 0;
  tab->gc_time = now;
  tab->gc_scheduled = 0;
}

static void
rt_event(void *ptr)
{
  rtable *tab = ptr;

  if (tab->hcu_scheduled)
    rt_update_hostcache(tab);

  if (tab->nhu_state)
    rt_next_hop_update(tab);

  if (tab->gc_scheduled)
    rt_prune_nets(tab);
}

void
rt_setup(pool *p, rtable *t, char *name, struct rtable_config *cf)
{
  bzero(t, sizeof(*t));
  fib_init(&t->fib, p, sizeof(net), 0, rte_init);
  t->name = name;
  t->config = cf;
  init_list(&t->hooks);
  if (cf)
    {
      t->rt_event = ev_new(p);
      t->rt_event->hook = rt_event;
      t->rt_event->data = t;
      t->gc_time = now;
    }
}

/**
 * rt_init - initialize routing tables
 *
 * This function is called during BIRD startup. It initializes the
 * routing table module.
 */
void
rt_init(void)
{
  rta_init();
  rt_table_pool = rp_new(&root_pool, "Routing tables");
  rte_update_pool = lp_new(rt_table_pool, 4080);
  rte_slab = sl_new(rt_table_pool, sizeof(rte));
  init_list(&routing_tables);
}


/* Called from proto_schedule_flush_loop() only,
   ensuring that all prune states are zero */
void
rt_schedule_prune_all(void)
{
  rtable *t;

  WALK_LIST(t, routing_tables)
    t->prune_state = 1;
}

static inline int
rt_prune_step(rtable *tab, int *max_feed)
{
  struct fib_iterator *fit = &tab->prune_fit;

  DBG("Pruning route table %s\n", tab->name);
#ifdef DEBUGGING
  fib_check(&tab->fib);
#endif

  if (tab->prune_state == 0)
    return 1;

  if (tab->prune_state == 1)
    {
      FIB_ITERATE_INIT(fit, &tab->fib);
      tab->prune_state = 2;
    }

again:
  FIB_ITERATE_START(&tab->fib, fit, fn)
    {
      net *n = (net *) fn;
      rte *e;

    rescan:
      for (e=n->routes; e; e=e->next)
	if (e->sender->proto->core_state != FS_HAPPY &&
	    e->sender->proto->core_state != FS_FEEDING)
	  {
	    if (*max_feed <= 0)
	      {
		FIB_ITERATE_PUT(fit, fn);
		return 0;
	      }

	    rte_discard(tab, e);
	    (*max_feed)--;

	    goto rescan;
	  }
      if (!n->routes)		/* Orphaned FIB entry */
	{
	  FIB_ITERATE_PUT(fit, fn);
	  fib_delete(&tab->fib, fn);
	  goto again;
	}
    }
  FIB_ITERATE_END(fn);

#ifdef DEBUGGING
  fib_check(&tab->fib);
#endif

  tab->prune_state = 0;
  return 1;
}

/**
 * rt_prune_loop - prune routing tables
 * @tab: routing table to be pruned
 *
 * The prune loop scans routing tables and removes routes belonging to
 * inactive protocols and also stale network entries. Returns 1 when
 * all such routes are pruned. It is a part of the protocol flushing
 * loop.
 */
int
rt_prune_loop(void)
{
  rtable *t;
  int max_feed = 512;

  WALK_LIST(t, routing_tables)
    if (! rt_prune_step(t, &max_feed))
      return 0;

  return 1;
}

void
rt_preconfig(struct config *c)
{
  struct symbol *s = cf_find_symbol("master");

  init_list(&c->tables);
  c->master_rtc = rt_new_table(s);
}


/* 
 * Some functions for handing internal next hop updates
 * triggered by rt_schedule_nhu().
 */

static inline int
rta_next_hop_outdated(rta *a)
{
  struct hostentry *he = a->hostentry;

  if (!he)
    return 0;

  if (!he->src)
    return a->dest != RTD_UNREACHABLE;

  return (a->iface != he->src->iface) || !ipa_equal(a->gw, he->gw) ||
    (a->dest != he->dest) || (a->igp_metric != he->igp_metric) ||
    !mpnh_same(a->nexthops, he->src->nexthops);
}

static inline void
rta_apply_hostentry(rta *a, struct hostentry *he)
{
  a->hostentry = he;
  a->iface = he->src ? he->src->iface : NULL;
  a->gw = he->gw;
  a->dest = he->dest;
  a->igp_metric = he->igp_metric;
  a->nexthops = he->src ? he->src->nexthops : NULL;
}

static inline rte *
rt_next_hop_update_rte(rtable *tab, rte *old)
{
  rta a;
  memcpy(&a, old->attrs, sizeof(rta));
  rta_apply_hostentry(&a, old->attrs->hostentry);
  a.aflags = 0;

  rte *e = sl_alloc(rte_slab);
  memcpy(e, old, sizeof(rte));
  e->attrs = rta_lookup(&a);

  return e;
}

static inline int
rt_next_hop_update_net(rtable *tab, net *n)
{
  rte **k, *e, *new, *old_best, **new_best;
  int count = 0;
  int free_old_best = 0;

  old_best = n->routes;
  if (!old_best)
    return 0;

  for (k = &n->routes; e = *k; k = &e->next)
    if (rta_next_hop_outdated(e->attrs))
      {
	new = rt_next_hop_update_rte(tab, e);
	*k = new;

	rte_announce_i(tab, RA_ANY, n, new, e);
	rte_trace_in(D_ROUTES, new->sender->proto, new, "updated");

	/* Call a pre-comparison hook */
	/* Not really an efficient way to compute this */
	if (e->attrs->proto->rte_recalculate)
	  e->attrs->proto->rte_recalculate(tab, n, new, e, NULL);

	if (e != old_best)
	  rte_free_quick(e);
	else /* Freeing of the old best rte is postponed */
	  free_old_best = 1;

	e = new;
	count++;
      }

  if (!count)
    return 0;

  /* Find the new best route */
  new_best = NULL;
  for (k = &n->routes; e = *k; k = &e->next)
    {
      if (!new_best || rte_better(e, *new_best))
	new_best = k;
    }

  /* Relink the new best route to the first position */
  new = *new_best;
  if (new != n->routes)
    {
      *new_best = new->next;
      new->next = n->routes;
      n->routes = new;
    }

  /* Announce the new best route */
  if (new != old_best)
    {
      rte_announce_i(tab, RA_OPTIMAL, n, new, old_best);
      rte_trace_in(D_ROUTES, new->sender->proto, new, "updated [best]");
    }

   if (free_old_best)
    rte_free_quick(old_best);

  return count;
}

static void
rt_next_hop_update(rtable *tab)
{
  struct fib_iterator *fit = &tab->nhu_fit;
  int max_feed = 32;

  if (tab->nhu_state == 0)
    return;

  if (tab->nhu_state == 1)
    {
      FIB_ITERATE_INIT(fit, &tab->fib);
      tab->nhu_state = 2;
    }

  FIB_ITERATE_START(&tab->fib, fit, fn)
    {
      if (max_feed <= 0)
	{
	  FIB_ITERATE_PUT(fit, fn);
	  ev_schedule(tab->rt_event);
	  return;
	}
      max_feed -= rt_next_hop_update_net(tab, (net *) fn);
    }
  FIB_ITERATE_END(fn);

  /* state change 2->0, 3->1 */
  tab->nhu_state &= 1;

  if (tab->nhu_state > 0)
    ev_schedule(tab->rt_event);
}


struct rtable_config *
rt_new_table(struct symbol *s)
{
  struct rtable_config *c = cfg_allocz(sizeof(struct rtable_config));

  cf_define_symbol(s, SYM_TABLE, c);
  c->name = s->name;
  add_tail(&new_config->tables, &c->n);
  c->gc_max_ops = 1000;
  c->gc_min_time = 5;
  return c;
}

/**
 * rt_lock_table - lock a routing table
 * @r: routing table to be locked
 *
 * Lock a routing table, because it's in use by a protocol,
 * preventing it from being freed when it gets undefined in a new
 * configuration.
 */
void
rt_lock_table(rtable *r)
{
  r->use_count++;
}

/**
 * rt_unlock_table - unlock a routing table
 * @r: routing table to be unlocked
 *
 * Unlock a routing table formerly locked by rt_lock_table(),
 * that is decrease its use count and delete it if it's scheduled
 * for deletion by configuration changes.
 */
void
rt_unlock_table(rtable *r)
{
  if (!--r->use_count && r->deleted)
    {
      struct config *conf = r->deleted;
      DBG("Deleting routing table %s\n", r->name);
      if (r->hostcache)
	rt_free_hostcache(r);
      rem_node(&r->n);
      fib_free(&r->fib);
      rfree(r->rt_event);
      mb_free(r);
      config_del_obstacle(conf);
    }
}

/**
 * rt_commit - commit new routing table configuration
 * @new: new configuration
 * @old: original configuration or %NULL if it's boot time config
 *
 * Scan differences between @old and @new configuration and modify
 * the routing tables according to these changes. If @new defines a
 * previously unknown table, create it, if it omits a table existing
 * in @old, schedule it for deletion (it gets deleted when all protocols
 * disconnect from it by calling rt_unlock_table()), if it exists
 * in both configurations, leave it unchanged.
 */
void
rt_commit(struct config *new, struct config *old)
{
  struct rtable_config *o, *r;

  DBG("rt_commit:\n");
  if (old)
    {
      WALK_LIST(o, old->tables)
	{
	  rtable *ot = o->table;
	  if (!ot->deleted)
	    {
	      struct symbol *sym = cf_find_symbol(o->name);
	      if (sym && sym->class == SYM_TABLE && !new->shutdown)
		{
		  DBG("\t%s: same\n", o->name);
		  r = sym->def;
		  r->table = ot;
		  ot->name = r->name;
		  ot->config = r;
		}
	      else
		{
		  DBG("\t%s: deleted\n", o->name);
		  ot->deleted = old;
		  config_add_obstacle(old);
		  rt_lock_table(ot);
		  rt_unlock_table(ot);
		}
	    }
	}
    }

  WALK_LIST(r, new->tables)
    if (!r->table)
      {
	rtable *t = mb_alloc(rt_table_pool, sizeof(struct rtable));
	DBG("\t%s: created\n", r->name);
	rt_setup(rt_table_pool, t, r->name, r);
	add_tail(&routing_tables, &t->n);
	r->table = t;
      }
  DBG("\tdone\n");
}

static inline void
do_feed_baby(struct proto *p, int type, struct announce_hook *h, net *n, rte *e)
{
  struct proto *src = e->attrs->proto;
  ea_list *tmpa;

  rte_update_lock();
  tmpa = src->make_tmp_attrs ? src->make_tmp_attrs(e, rte_update_pool) : NULL;
  if (type == RA_ACCEPTED)
    rt_notify_accepted(h, n, e, NULL, NULL, tmpa, p->refeeding ? 2 : 1);
  else
    rt_notify_basic(h, n, e, p->refeeding ? e : NULL, tmpa, p->refeeding);
  rte_update_unlock();
}

/**
 * rt_feed_baby - advertise routes to a new protocol
 * @p: protocol to be fed
 *
 * This function performs one pass of advertisement of routes to a newly
 * initialized protocol. It's called by the protocol code as long as it
 * has something to do. (We avoid transferring all the routes in single
 * pass in order not to monopolize CPU time.)
 */
int
rt_feed_baby(struct proto *p)
{
  struct announce_hook *h;
  struct fib_iterator *fit;
  int max_feed = 256;

  if (!p->feed_ahook)			/* Need to initialize first */
    {
      if (!p->ahooks)
	return 1;
      DBG("Announcing routes to new protocol %s\n", p->name);
      p->feed_ahook = p->ahooks;
      fit = p->feed_iterator = mb_alloc(p->pool, sizeof(struct fib_iterator));
      goto next_hook;
    }
  fit = p->feed_iterator;

again:
  h = p->feed_ahook;
  FIB_ITERATE_START(&h->table->fib, fit, fn)
    {
      net *n = (net *) fn;
      rte *e = n->routes;
      if (max_feed <= 0)
	{
	  FIB_ITERATE_PUT(fit, fn);
	  return 0;
	}

      if (p->accept_ra_types == RA_OPTIMAL)
	if (e)
	  {
	    if (p->core_state != FS_FEEDING)
	      return 1;  /* In the meantime, the protocol fell down. */
	    do_feed_baby(p, RA_OPTIMAL, h, n, e);
	    max_feed--;
	  }

      if (p->accept_ra_types == RA_ANY)
	for(e = n->routes; e != NULL; e = e->next)
	  {
	    if (p->core_state != FS_FEEDING)
	      return 1;  /* In the meantime, the protocol fell down. */
	    do_feed_baby(p, RA_ANY, h, n, e);
	    max_feed--;
	  }
    }
  FIB_ITERATE_END(fn);
  p->feed_ahook = h->next;
  if (!p->feed_ahook)
    {
      mb_free(p->feed_iterator);
      p->feed_iterator = NULL;
      return 1;
    }

next_hook:
  h = p->feed_ahook;
  FIB_ITERATE_INIT(fit, &h->table->fib);
  goto again;
}

/**
 * rt_feed_baby_abort - abort protocol feeding
 * @p: protocol
 *
 * This function is called by the protocol code when the protocol
 * stops or ceases to exist before the last iteration of rt_feed_baby()
 * has finished.
 */
void
rt_feed_baby_abort(struct proto *p)
{
  if (p->feed_ahook)
    {
      /* Unlink the iterator and exit */
      fit_get(&p->feed_ahook->table->fib, p->feed_iterator);
      p->feed_ahook = NULL;
    }
}


static inline unsigned
ptr_hash(void *ptr)
{
  uintptr_t p = (uintptr_t) ptr;
  return p ^ (p << 8) ^ (p >> 16);
}

static inline unsigned
hc_hash(ip_addr a, rtable *dep)
{
  return (ipa_hash(a) ^ ptr_hash(dep)) & 0xffff;
}

static inline void
hc_insert(struct hostcache *hc, struct hostentry *he)
{
  unsigned int k = he->hash_key >> hc->hash_shift;
  he->next = hc->hash_table[k];
  hc->hash_table[k] = he;
}

static inline void
hc_remove(struct hostcache *hc, struct hostentry *he)
{
  struct hostentry **hep;
  unsigned int k = he->hash_key >> hc->hash_shift;

  for (hep = &hc->hash_table[k]; *hep != he; hep = &(*hep)->next);
  *hep = he->next;
}

#define HC_DEF_ORDER 10
#define HC_HI_MARK *4
#define HC_HI_STEP 2
#define HC_HI_ORDER 16			/* Must be at most 16 */
#define HC_LO_MARK /5
#define HC_LO_STEP 2
#define HC_LO_ORDER 10

static void
hc_alloc_table(struct hostcache *hc, unsigned order)
{
  unsigned hsize = 1 << order;
  hc->hash_order = order;
  hc->hash_shift = 16 - order;
  hc->hash_max = (order >= HC_HI_ORDER) ? ~0 : (hsize HC_HI_MARK);
  hc->hash_min = (order <= HC_LO_ORDER) ?  0 : (hsize HC_LO_MARK);

  hc->hash_table = mb_allocz(rt_table_pool, hsize * sizeof(struct hostentry *));
}

static void
hc_resize(struct hostcache *hc, unsigned new_order)
{
  unsigned old_size = 1 << hc->hash_order;
  struct hostentry **old_table = hc->hash_table;
  struct hostentry *he, *hen;
  int i;

  hc_alloc_table(hc, new_order);
  for (i = 0; i < old_size; i++)
    for (he = old_table[i]; he != NULL; he=hen)
      {
	hen = he->next;
	hc_insert(hc, he);
      }
  mb_free(old_table);
}

static struct hostentry *
hc_new_hostentry(struct hostcache *hc, ip_addr a, ip_addr ll, rtable *dep, unsigned k)
{
  struct hostentry *he = sl_alloc(hc->slab);

  he->addr = a;
  he->link = ll;
  he->tab = dep;
  he->hash_key = k;
  he->uc = 0;
  he->src = NULL;

  add_tail(&hc->hostentries, &he->ln);
  hc_insert(hc, he);

  hc->hash_items++;
  if (hc->hash_items > hc->hash_max)
    hc_resize(hc, hc->hash_order + HC_HI_STEP);

  return he;
}

static void
hc_delete_hostentry(struct hostcache *hc, struct hostentry *he)
{
  rta_free(he->src);

  rem_node(&he->ln);
  hc_remove(hc, he);
  sl_free(hc->slab, he);

  hc->hash_items--;
  if (hc->hash_items < hc->hash_min)
    hc_resize(hc, hc->hash_order - HC_LO_STEP);
}

static void
rt_init_hostcache(rtable *tab)
{
  struct hostcache *hc = mb_allocz(rt_table_pool, sizeof(struct hostcache));
  init_list(&hc->hostentries);

  hc->hash_items = 0;
  hc_alloc_table(hc, HC_DEF_ORDER);
  hc->slab = sl_new(rt_table_pool, sizeof(struct hostentry));

  hc->lp = lp_new(rt_table_pool, 1008);
  hc->trie = f_new_trie(hc->lp);

  tab->hostcache = hc;
}

static void
rt_free_hostcache(rtable *tab)
{
  struct hostcache *hc = tab->hostcache;

  node *n;
  WALK_LIST(n, hc->hostentries)
    {
      struct hostentry *he = SKIP_BACK(struct hostentry, ln, n);
      rta_free(he->src);

      if (he->uc)
	log(L_ERR "Hostcache is not empty in table %s", tab->name);
    }

  rfree(hc->slab);
  rfree(hc->lp);
  mb_free(hc->hash_table);
  mb_free(hc);
}

static void
rt_notify_hostcache(rtable *tab, net *net)
{
  struct hostcache *hc = tab->hostcache;

  if (tab->hcu_scheduled)
    return;

  if (trie_match_prefix(hc->trie, net->n.prefix, net->n.pxlen))
    rt_schedule_hcu(tab);
}

static int
if_local_addr(ip_addr a, struct iface *i)
{
  struct ifa *b;

  WALK_LIST(b, i->addrs)
    if (ipa_equal(a, b->ip))
      return 1;

  return 0;
}

static u32 
rt_get_igp_metric(rte *rt)
{
  eattr *ea = ea_find(rt->attrs->eattrs, EA_GEN_IGP_METRIC);

  if (ea)
    return ea->u.data;

  rta *a = rt->attrs;

#ifdef CONFIG_OSPF
  if ((a->source == RTS_OSPF) ||
      (a->source == RTS_OSPF_IA) ||
      (a->source == RTS_OSPF_EXT1))
    return rt->u.ospf.metric1;
#endif

#ifdef CONFIG_RIP
  if (a->source == RTS_RIP)
    return rt->u.rip.metric;
#endif

  /* Device routes */
  if ((a->dest != RTD_ROUTER) && (a->dest != RTD_MULTIPATH))
    return 0;

  return IGP_METRIC_UNKNOWN;
}

static int
rt_update_hostentry(rtable *tab, struct hostentry *he)
{
  rta *old_src = he->src;
  int pxlen = 0;

  /* Reset the hostentry */ 
  he->src = NULL;
  he->gw = IPA_NONE;
  he->dest = RTD_UNREACHABLE;
  he->igp_metric = 0;

  net *n = net_route(tab, he->addr, MAX_PREFIX_LENGTH);
  if (n)
    {
      rta *a = n->routes->attrs;
      pxlen = n->n.pxlen;

      if (a->hostentry)
	{
	  /* Recursive route should not depend on another recursive route */
	  log(L_WARN "Next hop address %I resolvable through recursive route for %I/%d",
	      he->addr, n->n.prefix, pxlen);
	  goto done;
	}

      if (a->dest == RTD_DEVICE)
	{
	  if (if_local_addr(he->addr, a->iface))
	    {
	      /* The host address is a local address, this is not valid */
	      log(L_WARN "Next hop address %I is a local address of iface %s",
		  he->addr, a->iface->name);
	      goto done;
      	    }

	  /* The host is directly reachable, use link as a gateway */
	  he->gw = he->link;
	  he->dest = RTD_ROUTER;
	}
      else
	{
	  /* The host is reachable through some route entry */
	  he->gw = a->gw;
	  he->dest = a->dest;
	}

      he->src = rta_clone(a);
      he->igp_metric = rt_get_igp_metric(n->routes);
    }

 done:
  /* Add a prefix range to the trie */
  trie_add_prefix(tab->hostcache->trie, he->addr, MAX_PREFIX_LENGTH, pxlen, MAX_PREFIX_LENGTH);

  rta_free(old_src);
  return old_src != he->src;
}

static void
rt_update_hostcache(rtable *tab)
{
  struct hostcache *hc = tab->hostcache;
  struct hostentry *he;
  node *n, *x;

  /* Reset the trie */
  lp_flush(hc->lp);
  hc->trie = f_new_trie(hc->lp);

  WALK_LIST_DELSAFE(n, x, hc->hostentries)
    {
      he = SKIP_BACK(struct hostentry, ln, n);
      if (!he->uc)
	{
	  hc_delete_hostentry(hc, he);
	  continue;
	}

      if (rt_update_hostentry(tab, he))
	rt_schedule_nhu(he->tab);
    }

  tab->hcu_scheduled = 0;
}

static struct hostentry *
rt_find_hostentry(rtable *tab, ip_addr a, ip_addr ll, rtable *dep)
{
  struct hostentry *he;

  if (!tab->hostcache)
    rt_init_hostcache(tab);

  unsigned int k = hc_hash(a, dep);
  struct hostcache *hc = tab->hostcache;
  for (he = hc->hash_table[k >> hc->hash_shift]; he != NULL; he = he->next)
    if (ipa_equal(he->addr, a) && (he->tab == dep))
      return he;

  he = hc_new_hostentry(hc, a, ll, dep, k);
  rt_update_hostentry(tab, he);
  return he;
}

void
rta_set_recursive_next_hop(rtable *dep, rta *a, rtable *tab, ip_addr *gw, ip_addr *ll)
{
  rta_apply_hostentry(a, rt_find_hostentry(tab, *gw, *ll, dep));
}

/*
 *  CLI commands
 */

static void
rt_format_via(rte *e, byte *via)
{
  rta *a = e->attrs;

  switch (a->dest)
    {
    case RTD_ROUTER:	bsprintf(via, "via %I on %s", a->gw, a->iface->name); break;
    case RTD_DEVICE:	bsprintf(via, "dev %s", a->iface->name); break;
    case RTD_BLACKHOLE:	bsprintf(via, "blackhole"); break;
    case RTD_UNREACHABLE:	bsprintf(via, "unreachable"); break;
    case RTD_PROHIBIT:	bsprintf(via, "prohibited"); break;
    case RTD_MULTIPATH:	bsprintf(via, "multipath"); break;
    default:		bsprintf(via, "???");
    }
}

static void
rt_show_rte(struct cli *c, byte *ia, rte *e, struct rt_show_data *d, ea_list *tmpa)
{
  byte via[STD_ADDRESS_P_LENGTH+32], from[STD_ADDRESS_P_LENGTH+8];
  byte tm[TM_DATETIME_BUFFER_SIZE], info[256];
  rta *a = e->attrs;
  int primary = (e->net->routes == e);
  int sync_error = (e->net->n.flags & KRF_SYNC_ERROR);
  struct mpnh *nh;

  rt_format_via(e, via);
  tm_format_datetime(tm, &config->tf_route, e->lastmod);
  if (ipa_nonzero(a->from) && !ipa_equal(a->from, a->gw))
    bsprintf(from, " from %I", a->from);
  else
    from[0] = 0;
  if (a->proto->proto->get_route_info || d->verbose)
    {
      /* Need to normalize the extended attributes */
      ea_list *t = tmpa;
      t = ea_append(t, a->eattrs);
      tmpa = alloca(ea_scan(t));
      ea_merge(t, tmpa);
      ea_sort(tmpa);
    }
  if (a->proto->proto->get_route_info)
    a->proto->proto->get_route_info(e, info, tmpa);
  else
    bsprintf(info, " (%d)", e->pref);
  cli_printf(c, -1007, "%-18s %s [%s %s%s]%s%s", ia, via, a->proto->name,
	     tm, from, primary ? (sync_error ? " !" : " *") : "", info);
  for (nh = a->nexthops; nh; nh = nh->next)
    cli_printf(c, -1007, "\tvia %I on %s weight %d", nh->gw, nh->iface->name, nh->weight + 1);
  if (d->verbose)
    rta_show(c, a, tmpa);
}

static void
rt_show_net(struct cli *c, net *n, struct rt_show_data *d)
{
  rte *e, *ee;
  byte ia[STD_ADDRESS_P_LENGTH+8];
  struct announce_hook *a;
  int ok;

  bsprintf(ia, "%I/%d", n->n.prefix, n->n.pxlen);
  if (n->routes)
    d->net_counter++;
  for(e=n->routes; e; e=e->next)
    {
      struct ea_list *tmpa, *old_tmpa;
      struct proto *p0 = e->attrs->proto;
      struct proto *p1 = d->export_protocol;
      struct proto *p2 = d->show_protocol;
      d->rt_counter++;
      ee = e;
      rte_update_lock();		/* We use the update buffer for filtering */
      old_tmpa = tmpa = p0->make_tmp_attrs ? p0->make_tmp_attrs(e, rte_update_pool) : NULL;
      ok = (d->filter == FILTER_ACCEPT || f_run(d->filter, &e, &tmpa, rte_update_pool, FF_FORCE_TMPATTR) <= F_ACCEPT);
      if (p2 && p2 != p0) ok = 0;
      if (ok && d->export_mode)
	{
	  int ic;
	  if ((ic = p1->import_control ? p1->import_control(p1, &e, &tmpa, rte_update_pool) : 0) < 0)
	    ok = 0;
	  else if (!ic && d->export_mode > 1)
	    {
	      /* FIXME - this shows what should be exported according
		 to current filters, but not what was really exported.
		 'configure soft' command may change the export filter
		 and do not update routes */

	      if ((a = proto_find_announce_hook(p1, d->table)) && ((a->out_filter == FILTER_REJECT) ||
		  (a->out_filter && f_run(a->out_filter, &e, &tmpa, rte_update_pool, FF_FORCE_TMPATTR) > F_ACCEPT)))
		ok = 0;
	    }
	}
      if (ok)
	{
	  d->show_counter++;
	  if (d->stats < 2)
	    rt_show_rte(c, ia, e, d, tmpa);
	  ia[0] = 0;
	}
      if (e != ee)
      {
	rte_free(e);
	e = ee;
      }
      rte_update_unlock();
      if (d->primary_only)
	break;
    }
}

static void
rt_show_cont(struct cli *c)
{
  struct rt_show_data *d = c->rover;
#ifdef DEBUGGING
  unsigned max = 4;
#else
  unsigned max = 64;
#endif
  struct fib *fib = &d->table->fib;
  struct fib_iterator *it = &d->fit;

  FIB_ITERATE_START(fib, it, f)
    {
      net *n = (net *) f;
      if (d->running_on_config && d->running_on_config != config)
	{
	  cli_printf(c, 8004, "Stopped due to reconfiguration");
	  goto done;
	}
      if (d->export_protocol &&
	  d->export_protocol->core_state != FS_HAPPY &&
	  d->export_protocol->core_state != FS_FEEDING)
	{
	  cli_printf(c, 8005, "Protocol is down");
	  goto done;
	}
      if (!max--)
	{
	  FIB_ITERATE_PUT(it, f);
	  return;
	}
      rt_show_net(c, n, d);
    }
  FIB_ITERATE_END(f);
  if (d->stats)
    cli_printf(c, 14, "%d of %d routes for %d networks", d->show_counter, d->rt_counter, d->net_counter);
  else
    cli_printf(c, 0, "");
done:
  c->cont = c->cleanup = NULL;
}

static void
rt_show_cleanup(struct cli *c)
{
  struct rt_show_data *d = c->rover;

  /* Unlink the iterator */
  fit_get(&d->table->fib, &d->fit);
}

void
rt_show(struct rt_show_data *d)
{
  net *n;

  if (d->pxlen == 256)
    {
      FIB_ITERATE_INIT(&d->fit, &d->table->fib);
      this_cli->cont = rt_show_cont;
      this_cli->cleanup = rt_show_cleanup;
      this_cli->rover = d;
    }
  else
    {
      if (d->show_for)
	n = net_route(d->table, d->prefix, d->pxlen);
      else
	n = net_find(d->table, d->prefix, d->pxlen);
      if (n)
	{
	  rt_show_net(this_cli, n, d);
	  cli_msg(0, "");
	}
      else
	cli_msg(8001, "Network not in table");
    }
}

/*
 *  Documentation for functions declared inline in route.h
 */
#if 0

/**
 * net_find - find a network entry
 * @tab: a routing table
 * @addr: address of the network
 * @len: length of the network prefix
 *
 * net_find() looks up the given network in routing table @tab and
 * returns a pointer to its &net entry or %NULL if no such network
 * exists.
 */
static inline net *net_find(rtable *tab, ip_addr addr, unsigned len)
{ DUMMY; }

/**
 * net_get - obtain a network entry
 * @tab: a routing table
 * @addr: address of the network
 * @len: length of the network prefix
 *
 * net_get() looks up the given network in routing table @tab and
 * returns a pointer to its &net entry. If no such entry exists, it's
 * created.
 */
static inline net *net_get(rtable *tab, ip_addr addr, unsigned len)
{ DUMMY; }

/**
 * rte_cow - copy a route for writing
 * @r: a route entry to be copied
 *
 * rte_cow() takes a &rte and prepares it for modification. The exact action
 * taken depends on the flags of the &rte -- if it's a temporary entry, it's
 * just returned unchanged, else a new temporary entry with the same contents
 * is created.
 *
 * The primary use of this function is inside the filter machinery -- when
 * a filter wants to modify &rte contents (to change the preference or to
 * attach another set of attributes), it must ensure that the &rte is not
 * shared with anyone else (and especially that it isn't stored in any routing
 * table).
 *
 * Result: a pointer to the new writable &rte.
 */
static inline rte * rte_cow(rte *r)
{ DUMMY; }

#endif