/*
 *	BIRD -- OSPF
 *
 *	(c) 2000--2004 Ondrej Filip <feela@network.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#include "ospf.h"
static void add_cand(list * l, struct top_hash_entry *en,
		     struct top_hash_entry *par, u16 dist,
		     struct ospf_area *oa);
static void calc_next_hop(struct top_hash_entry *en,
			  struct top_hash_entry *par, struct ospf_area *oa);
static void ospf_ext_spfa(struct proto_ospf *po);

void
init_infib(struct fib_node *fn)
{
  struct infib *f = (struct infib *) fn;

  f->metric = LSINFINITY;
  f->oldmetric = LSINFINITY;
  f->en = NULL;
  f->olden = NULL;
}

void
init_efib(struct fib_node *fn)
{
  struct extfib *f = (struct extfib *) fn;

  f->metric = LSINFINITY;
  f->metric2 = LSINFINITY;
  f->nh = ipa_from_u32(0);
  f->nhi = NULL;
  f->oldmetric = LSINFINITY;
  f->oldmetric2 = LSINFINITY;
  f->oldnh = ipa_from_u32(0);
}

/**
 * ospf_rt_spf - calculate internal routes
 * @po: OSPF protocol
 *
 * Calculation of internal paths in an area is described in 16.1 of RFC 2328.
 * It's based on Dijkstra's shortest path tree algorithms.
 * RFC recommends to add ASBR routers into routing table. I don't do this
 * and latter parts of routing table calculation look directly into LSA
 * Database. This function is invoked from ospf_disp().
 */
void
ospf_rt_spfa(struct ospf_area *oa)
{
  u32 i, *rts;
  struct ospf_lsa_rt *rt;
  struct ospf_lsa_rt_link *rtl, *rr;
  struct fib *in = &oa->infib;
  struct infib *nf;
  struct fib_iterator fit;
  struct proto *p = &oa->po->proto;
  struct proto_ospf *po = oa->po;
  ip_addr ip;
  struct ospf_lsa_net *ln;

  OSPF_TRACE(D_EVENTS, "Starting routing table calculation for area %I",
	     oa->areaid);

  if (oa->rt == NULL)
    return;
#if 0
  if (oa->rt->dist != LSINFINITY)
#endif
    ospf_age(oa);

  FIB_WALK(in, nftmp)
  {
    nf = (struct infib *) nftmp;
    nf->metric = LSINFINITY;
    nf->en = NULL;
  }
  FIB_WALK_END;

  init_list(&oa->cand);		/* Empty list of candidates */
  oa->trcap = 0;

  DBG("LSA db prepared, adding me into candidate list.\n");

  oa->rt->dist = 0;
  oa->rt->color = CANDIDATE;
  add_head(&oa->cand, &oa->rt->cn);
  DBG("RT LSA: rt: %I, id: %I, type: %u\n", oa->rt->lsa.rt,
      oa->rt->lsa.id, oa->rt->lsa.type);

  while (!EMPTY_LIST(oa->cand))
  {
    struct top_hash_entry *act, *tmp;
    node *n;
    u16 met;

    n = HEAD(oa->cand);
    act = SKIP_BACK(struct top_hash_entry, cn, n);
    rem_node(n);

    DBG("Working on LSA: rt: %I, id: %I, type: %u\n", act->lsa.rt,
	act->lsa.id, act->lsa.type);

    act->color = INSPF;
    switch (act->lsa.type)
    {
    case LSA_T_RT:
      rt = (struct ospf_lsa_rt *) act->lsa_body;
      if (rt->veb.bit.v)
	oa->trcap = 1;
      rr = (struct ospf_lsa_rt_link *) (rt + 1);
      DBG("  Number of links: %u\n", rt->links);
      for (i = 0; i < rt->links; i++)
      {
	tmp = NULL;
	rtl = (rr + i);
	DBG("     Working on link: %I (type: %u)  ", rtl->id, rtl->type);
	switch (rtl->type)
	{
	case LSART_STUB:
	  /* This violates rfc2328! but I hope it's also correct. */
	  DBG("\n");
	  ip = ipa_from_u32(rtl->id);
	  nf = fib_get(in, &ip, ipa_mklen(ipa_from_u32(rtl->data)));
	  if (nf->metric > (met = act->dist + rtl->metric))
	  {
	    DBG("       Adding stub route....\n");
	    if (oa->rt == act)
	      break;
	    if (act->nhi == NULL)
	      break;
	    nf->metric = met;
	    nf->en = act;
	    DBG("            Adding stub route: %I\n", ip);
	    DBG("            Next hop=%I\n", nf->en->nh);
	  }
	  else
	    DBG("            NOT adding stub route: %I\n", ip);
	  break;
	case LSART_VLNK:
	  DBG("Ignoring\n");
	  continue;
	  break;
	case LSART_NET:
	  tmp = ospf_hash_find(oa->gr, rtl->id, rtl->id, LSA_T_NET);
	  if (tmp == NULL)
	    DBG("Not found!\n");
	  else
	    DBG("Found. :-)\n");
	  break;
	case LSART_PTP:
	  tmp = ospf_hash_find(oa->gr, rtl->id, rtl->id, LSA_T_RT);
	  DBG("PTP found.\n");
	  break;
	default:
	  log("Unknown link type in router lsa.");
	  break;
	}
	if (tmp)
	  DBG("Going to add cand, Mydist: %u, Req: %u\n",
	      tmp->dist, act->dist + rtl->metric);
	add_cand(&oa->cand, tmp, act, act->dist + rtl->metric, oa);
      }
      break;
    case LSA_T_NET:
      ln = act->lsa_body;
      ip = ipa_and(ipa_from_u32(act->lsa.id), ln->netmask);
      nf = fib_get(in, &ip, ipa_mklen(ln->netmask));
      if (nf->metric > act->dist)
      {
	nf->metric = act->dist;
	nf->en = act;
	DBG("    Adding into routing table\n");
      }
      rts = (u32 *) (ln + 1);
      for (i = 0; i < (act->lsa.length - sizeof(struct ospf_lsa_header) -
		       sizeof(struct ospf_lsa_net)) / sizeof(u32); i++)
      {
	DBG("     Working on router %I ", *(rts + i));
	tmp = ospf_hash_find(oa->gr, *(rts + i), *(rts + i), LSA_T_RT);
	if (tmp != NULL)
	  DBG("Found :-)\n");
	else
	  DBG("Not found!\n");
	add_cand(&oa->cand, tmp, act, act->dist, oa);
      }
      break;
    }
  }
  /* Now sync our fib with nest's */
  DBG("Now syncing my rt table with nest's\n");
  FIB_ITERATE_INIT(&fit, in);
again:
  FIB_ITERATE_START(in, &fit, nftmp)
  {
    nf = (struct infib *) nftmp;
    if (nf->metric == LSINFINITY)
    {
      net *ne;
      struct top_hash_entry *en = nf->en;
      ln = en->lsa_body;

      ne = net_get(p->table, nf->fn.prefix, nf->fn.pxlen);
      if ((en != NULL) && (en->nhi != NULL))
	DBG("Deleting rt entry %I\n     (P: %x, GW: %I, Iface: %s)\n",
	    nf->fn.prefix, en, en->nh, en->nhi->name);
      rte_update(p->table, ne, p, NULL);

      /* Now delete my fib */
      FIB_ITERATE_PUT(&fit, nftmp);
      fib_delete(in, nftmp);
      goto again;
    }
    else
    {
      /* Update routing table */
      if (ipa_equal(nf->en->nh, ipa_from_u32(0)))
      {
	struct top_hash_entry *en = nf->en;
	struct ospf_neighbor *neigh;
	neighbor *nn;

	if ((neigh = find_neigh_noifa(po, en->lsa.rt)) == NULL)
	{
	  goto skip;
	}
	nn = neigh_find(p, &neigh->ip, 0);
	DBG("     Next hop calculated: %I\n", nn->addr);
	en->nh = nn->addr;
	en->nhi = nn->iface;
      }

      if ((nf->en != nf->olden) || (nf->metric != nf->oldmetric))
      {
	net *ne;
	rta a0;
	rte *e;
	struct top_hash_entry *en = nf->en;
	ln = en->lsa_body;

	bzero(&a0, sizeof(a0));

	a0.proto = p;
	a0.source = RTS_OSPF;
	a0.scope = SCOPE_UNIVERSE;
	a0.cast = RTC_UNICAST;
	if (ipa_to_u32(en->nh) == 0)
	  a0.dest = RTD_DEVICE;
	else
	  a0.dest = RTD_ROUTER;
	a0.flags = 0;
	a0.aflags = 0;
	a0.iface = en->nhi;
	a0.gw = en->nh;

	ne = net_get(p->table, nf->fn.prefix, nf->fn.pxlen);
	e = rte_get_temp(&a0);
	e->u.ospf.metric1 = nf->metric;
	e->u.ospf.metric2 = LSINFINITY;
	e->u.ospf.tag = 0;
	e->pflags = 0;
	e->net = ne;
	e->pref = p->preference;
	DBG("Modifying rt entry %I\n     (GW: %I, Iface: %s)\n",
	    nf->fn.prefix, en->nh, en->nhi->name);
	rte_update(p->table, ne, p, e);

	nf->olden = nf->en;
	nf->oldmetric = nf->metric;
      }
    }

  }
skip:
  FIB_ITERATE_END(nftmp);
  ospf_ext_spfa(po);
}


void
ospf_rt_spf(struct proto_ospf *po)
{
  struct ospf_area *oa;
  WALK_LIST(oa, po->area_list)
  {
    ospf_rt_spfa(oa);
  }
}


/**
 * ospf_ext_spfa - calculate external paths
 * @po: protocol
 *
 * After routing table for any area is calculated, calculation of external
 * path is invoked. This process is described in 16.6 of RFC 2328.
 * Inter- and Intra-area paths are always prefered over externals.
 */
static void
ospf_ext_spfa(struct proto_ospf *po)	/* FIXME looking into inter-area */
{
  struct top_hash_entry *en, *etmp, *absr;
  struct fib *ef = &po->efib;
  struct extfib *nf;
  struct infib *inf;
  struct fib_iterator fit;
  struct ospf_area *oa = NULL, *atmp, *absroa;
  struct proto *p = &po->proto;
  struct ospf_lsa_ext *le;
  struct ospf_lsa_ext_tos *lt;
  int mlen;
  ip_addr ip, nnh;
  struct iface *nnhi = NULL;
  u16 met, met2;
  u32 tag;
  neighbor *nn;

  OSPF_TRACE(D_EVENTS, "Starting routing table calculation for ext routes");

  FIB_WALK(ef, nftmp)
  {
    nf = (struct extfib *) nftmp;
    nf->metric = LSINFINITY;
    nf->metric2 = LSINFINITY;
  }
  FIB_WALK_END;

  WALK_LIST(oa, po->area_list)
  {
    if (!oa->stub)
      break;
  }

  if (oa == NULL)
    return;

  WALK_SLIST(en, oa->lsal)
  {
    if (en->lsa.type != LSA_T_EXT)
      continue;
    if (en->lsa.age == LSA_MAXAGE)
      continue;
    if (en->lsa.rt == p->cf->global->router_id)
      continue;

    le = en->lsa_body;
    lt = (struct ospf_lsa_ext_tos *) (le + 1);

    DBG("%s: Working on LSA. ID: %I, RT: %I, Type: %u, Mask %I\n",
	p->name, en->lsa.id, en->lsa.rt, en->lsa.type, le->netmask);

    if (lt->metric == LSINFINITY)
      continue;
    ip = ipa_and(ipa_from_u32(en->lsa.id), le->netmask);
    mlen = ipa_mklen(le->netmask);
    if ((mlen < 0) || (mlen > 32))
    {
      log("%s: Invalid mask in LSA. ID: %I, RT: %I, Type: %u, Mask %I",
	  p->name, en->lsa.id, en->lsa.rt, en->lsa.type, le->netmask);
      continue;
    }

    nf = NULL;

    WALK_LIST(atmp, po->area_list)
    {
      if ((nf = fib_find(&atmp->infib, &ip, mlen)) != NULL)
	break;
    }

    if (nf != NULL)
      continue;			/* Some intra area path exists */

    absr = NULL;
    absroa = NULL;
    nnhi = NULL;
    nnh = IPA_NONE;

    met = 0;
    met2 = 0;
    tag = 0;

    WALK_LIST(atmp, po->area_list)	/*
					 * Find shortest path
					 * to advertising router 
					 */
    {
      if ((etmp =
	   ospf_hash_find(atmp->gr, en->lsa.rt, en->lsa.rt,
			  LSA_T_RT)) != NULL)
      {
	if ((absr == NULL) || (absr->dist > etmp->dist) ||
	    ((etmp->dist == absr->dist) && (absroa->areaid < atmp->areaid)))
	{
	  absr = etmp;
	  absroa = atmp;
	  break;
	}
      }
    }

    if ((absr == NULL) || (absr->dist == LSINFINITY) ||
	(((struct ospf_lsa_rt *) (absr->lsa_body))->veb.bit.e == 0))
    {
      DBG("ASBR is null or its dist=INF\n");
      continue;
    }

    if (ipa_compare(lt->fwaddr, ipa_from_u32(0)) == 0)
    {
      if (lt->etos > 0)		/* FW address == 0 */
      {
	met = absr->dist;
	met2 = lt->metric;
      }
      else
      {
	met = absr->dist + lt->metric;
	met2 = LSINFINITY;
      }
      tag = lt->tag;
    }
    else			/* FW address !=0 */
    {
      inf = NULL;
      WALK_LIST(atmp, po->area_list)
      {
	if ((inf = fib_route(&atmp->infib, lt->fwaddr, 32)) != NULL)
	{
	  break;
	}
      }

      if (inf == NULL)
      {
	DBG("Cannot find network route (GW=%I)\n", lt->fwaddr);
	continue;
      }

      if (lt->etos > 0)
      {
	met = inf->metric;
	met2 = lt->metric;
      }
      else
      {
	met = inf->metric + lt->metric;
	met2 = LSINFINITY;
      }
      tag = lt->tag;

      if ((nn = neigh_find(p, &lt->fwaddr, 0)) != NULL)
      {
	nnh = lt->fwaddr;
	nnhi = nn->iface;
      }
      else
      {
	nnh = inf->en->nh;
	nnhi = inf->en->nhi;
      }
    }

    nf = fib_get(ef, &ip, mlen);
    if ((nf->metric == LSINFINITY) ||	/* nf is new */
	((met < nf->metric) && (nf->metric2 == met2)) ||	/* both E1 or E2
								 * with same metric */
	((met2 < nf->metric2) && (nf->metric2 != LSINFINITY)) ||	/* E2 smaller and
									 * 1st is not E1 */
	((nf->metric2 != LSINFINITY) && (met2 == LSINFINITY)))	/* 2nd is E1 and
								 * 1st is E2 */
    {
      if (nf->metric != LSINFINITY)
	OSPF_TRACE(D_EVENTS,
		   "Rewriting %I/%d met=%d, met2=%d, nmet=%d, nmet2=%d",
		   ip, mlen, nf->metric, nf->metric2, met, met2);
      nf->metric = met;
      nf->metric2 = met2;
      nf->tag = tag;

      if (nnhi != NULL)
      {
	nf->nh = nnh;
	nf->nhi = nnhi;
      }
      else
      {
	if (ipa_compare(absr->nh, ipa_from_u32(0)) == 0)
	{
	  struct ospf_neighbor *neigh;

	  if ((neigh = find_neigh_noifa(po, absr->lsa.rt)) == NULL)
	  {
	    DBG("Cannot find neighbor\n");
	    nf->metric = LSINFINITY;	/* delete this route */
	    continue;
	  }
	  nn = neigh_find(p, &neigh->ip, 0);
	  DBG("     Next hop calculated: %I\n", nn->addr);
	  nf->nh = nn->addr;
	  nf->nhi = nn->iface;
	}
	else
	{
	  nf->nh = absr->nh;
	  nf->nhi = absr->nhi;
	}
      }
    }
  }

  DBG("Now syncing my rt table with nest's\n");
  FIB_ITERATE_INIT(&fit, ef);
noch:
  FIB_ITERATE_START(ef, &fit, nftmp)
  {
    nf = (struct extfib *) nftmp;
    if (nf->metric == LSINFINITY)
    {
      net *ne;

      ne = net_get(p->table, nf->fn.prefix, nf->fn.pxlen);
      DBG("Deleting rt entry %I\n     (IP: %I, GW: %I)\n",
	  nf->fn.prefix, ip, nf->nh);
      rte_update(p->table, ne, p, NULL);

      /* Now delete my fib */
      FIB_ITERATE_PUT(&fit, nftmp);
      fib_delete(ef, nftmp);
      goto noch;
    }
    else
      if ((nf->metric != nf->oldmetric) || (nf->metric2 != nf->oldmetric2) ||
	  (!ipa_equal(nf->nh, nf->oldnh)) || (nf->tag != nf->oldtag))
    {
      net *ne;
      rta a0;
      rte *e;

      bzero(&a0, sizeof(a0));

      a0.proto = p;
      a0.source = RTS_OSPF_EXT;
      a0.scope = SCOPE_UNIVERSE;
      a0.cast = RTC_UNICAST;
      a0.dest = RTD_ROUTER;
      a0.flags = 0;
      a0.aflags = 0;
      a0.iface = nf->nhi;
      a0.gw = nf->nh;
      ne = net_get(p->table, nf->fn.prefix, nf->fn.pxlen);
      e = rte_get_temp(&a0);
      e->u.ospf.metric1 = nf->metric;
      e->u.ospf.metric2 = nf->metric2;
      e->u.ospf.tag = nf->tag;
      e->pflags = 0;
      e->net = ne;
      e->pref = p->preference;
      DBG("Modifying rt entry %I\n     (IP: %I, GW: %I)\n",
	  nf->fn.prefix, ip, nf->nh);
      rte_update(p->table, ne, p, e);

      nf->oldmetric = nf->metric;
      nf->oldmetric2 = nf->metric2;
      nf->oldnh = nf->nh;
      nf->oldtag = nf->tag;
    }
  }
  FIB_ITERATE_END(nftmp);
}

/* Add LSA into list of candidates in Dijkstra's algorithm */
static void
add_cand(list * l, struct top_hash_entry *en, struct top_hash_entry *par,
	 u16 dist, struct ospf_area *oa)
{
  node *prev, *n;
  int added = 0;
  struct top_hash_entry *act;

  if (en == NULL)
    return;
  if (en->lsa.age == LSA_MAXAGE)
    return;
  /* FIXME Does it have link back? Test it! */
  if (en->color == INSPF)
    return;

  if (dist >= en->dist)
    return;
  /*
   * FIXME The line above is not a bug, but we don't support
   * multiple next hops. I'll start as soon as nest will
   */
  DBG("     Adding candidate: rt: %I, id: %I, type: %u\n", en->lsa.rt,
      en->lsa.id, en->lsa.type);

  en->nhi = NULL;
  en->nh = IPA_NONE;

  calc_next_hop(en, par, oa);

  if (!en->nhi)
    return;			/* We cannot find next hop, ignore it */

  if (en->color == CANDIDATE)	/* We found a shorter path */
  {
    rem_node(&en->cn);
  }

  en->dist = dist;
  en->color = CANDIDATE;

  prev = NULL;

  if (EMPTY_LIST(*l))
  {
    add_head(l, &en->cn);
  }
  else
  {
    WALK_LIST(n, *l)
    {
      act = SKIP_BACK(struct top_hash_entry, cn, n);
      if ((act->dist > dist) ||
	  ((act->dist == dist) && (act->lsa.type == LSA_T_NET)))
      {
	if (prev == NULL)
	  add_head(l, &en->cn);
	else
	  insert_node(&en->cn, prev);
	added = 1;
	break;
      }
      prev = n;
    }

    if (!added)
    {
      add_tail(l, &en->cn);
    }
  }
  /* FIXME Some VLINK stuff should be here */
}

static void
calc_next_hop(struct top_hash_entry *en, struct top_hash_entry *par,
	      struct ospf_area *oa)
{
  struct ospf_neighbor *neigh;
  struct proto *p = &oa->po->proto;
  struct proto_ospf *po = oa->po;
  struct ospf_iface *ifa;
  u32 myrid = p->cf->global->router_id;

  DBG("     Next hop called.\n");
  if (ipa_equal(par->nh, IPA_NONE))
  {
    neighbor *nn;
    DBG("     Next hop calculating for id: %I rt: %I type: %u\n",
	en->lsa.id, en->lsa.rt, en->lsa.type);

    if (par == oa->rt)
    {
      if (en->lsa.type == LSA_T_NET)
      {
	if (en->lsa.rt == myrid)
	{
	  WALK_LIST(ifa, po->iface_list)
	    if (ipa_compare
		(ifa->iface->addr->ip, ipa_from_u32(en->lsa.id)) == 0)
	  {
	    en->nhi = ifa->iface;
	    return;
	  }
	  log(L_ERR "I didn't find interface for my self originated LSA!\n");
	  /* This could sometimes happen */
	  return;
	}
	else
	{
	  ip_addr ip = ipa_from_u32(en->lsa.id);
	  nn = neigh_find(p, &ip, 0);
	  if (nn)
	    en->nhi = nn->iface;
	  return;
	}
      }
      else
      {
	if ((neigh = find_neigh_noifa(po, en->lsa.rt)) == NULL)
	  return;
	en->nhi = neigh->ifa->iface;
	en->nh = neigh->ip;	/* Yes, neighbor is it's own next hop */
	return;
      }
    }

    if (par->lsa.type == LSA_T_NET)
    {
      if (en->lsa.type == LSA_T_NET)
	bug("Parent for net is net?");
      if ((en->nhi = par->nhi) == NULL)
	bug("Did not find next hop interface for INSPF lsa!");
      if ((neigh = find_neigh_noifa(po, en->lsa.rt)) == NULL)
	return;
      en->nhi = neigh->ifa->iface;
      en->nh = neigh->ip;	/* Yes, neighbor is it's own next hop */
      return;
    }
    else			/* Parent is some RT neighbor */
    {
      log(L_ERR "Router's parent has no next hop. (EN=%I, PAR=%I)",
	  en->lsa.id, par->lsa.id);
      /* I hoped this would never happen */
      return;
    }
  }
  en->nh = par->nh;
  en->nhi = par->nhi;
  DBG("     Next hop calculated: %I.\n", en->nh);
}
