// SPDX-License-Identifier: GPL-2.0-or-later

/*

 * OSPF Flooding -- RFC2328 Section 13.

 * Copyright (C) 1999, 2000 Toshiaki Takada

 */

#include <zebra.h>

#include "monotime.h"

#include "linklist.h"

#include "prefix.h"

#include "if.h"

#include "command.h"

#include "table.h"

#include "frrevent.h"

#include "memory.h"

#include "log.h"

#include "zclient.h"

#include "ospfd/ospfd.h"

#include "ospfd/ospf_interface.h"

#include "ospfd/ospf_ism.h"

#include "ospfd/ospf_asbr.h"

#include "ospfd/ospf_lsa.h"

#include "ospfd/ospf_lsdb.h"

#include "ospfd/ospf_neighbor.h"

#include "ospfd/ospf_nsm.h"

#include "ospfd/ospf_spf.h"

#include "ospfd/ospf_flood.h"

#include "ospfd/ospf_packet.h"

#include "ospfd/ospf_abr.h"

#include "ospfd/ospf_route.h"

#include "ospfd/ospf_zebra.h"

#include "ospfd/ospf_dump.h"

extern struct zclient *zclient;

/** @brief Function to refresh type-5 and type-7 DNA

 *     LSAs when we receive an indication LSA.

 *  @param Ospf instance.

 *  @return Void.

 */

void ospf_refresh_dna_type5_and_type7_lsas(struct ospf *ospf)

{

  struct route_node *rn;

  struct ospf_lsa *lsa = NULL;

  LSDB_LOOP (EXTERNAL_LSDB(ospf), rn, lsa)

    if (IS_LSA_SELF(lsa) &&

        CHECK_FLAG(lsa->data->ls_age, DO_NOT_AGE))

      ospf_lsa_refresh(ospf, lsa);

  LSDB_LOOP (NSSA_LSDB(ospf), rn, lsa)

    if (IS_LSA_SELF(lsa) &&

        CHECK_FLAG(lsa->data->ls_age, DO_NOT_AGE))

      ospf_lsa_refresh(ospf, lsa);

}

/** @brief Function to update area flood reduction states.

 *  @param area pointer.

 *  @return Void.

 */

void ospf_area_update_fr_state(struct ospf_area *area)

{

  unsigned int count_router_lsas = 0;

  if (area == NULL)

    return;

  count_router_lsas =

    (unsigned int)(ospf_lsdb_count(area->lsdb, OSPF_ROUTER_LSA) -

             ospf_lsdb_count_self(area->lsdb,

                OSPF_ROUTER_LSA));

  if (count_router_lsas >

      (unsigned int)area->fr_info.router_lsas_recv_dc_bit) {

    area->fr_info.enabled = false;

    area->fr_info.area_dc_clear = true;

    return;

  } else if (count_router_lsas <

       (unsigned int)area->fr_info.router_lsas_recv_dc_bit) {

    /* This can never happen, total number of router lsas received

     * can never be less than router lsas received with dc bit set

     */

    OSPF_LOG_ERR("%s: Counter mismatch for area %pI4", __func__,

           &area->area_id);

    OSPF_LOG_ERR(

      "%s: router LSAs in lsdb %d router LSAs recvd with dc bit set %d",

      __func__, count_router_lsas,

      area->fr_info.router_lsas_recv_dc_bit);

    return;

  }

  area->fr_info.area_dc_clear = false;

  if (OSPF_FR_CONFIG(area->ospf, area)) {

    if (!area->fr_info.enabled) {

      area->fr_info.enabled = true;

      area->fr_info.state_changed = true;

    }

  } else {

    area->fr_info.enabled = false;

    area->fr_info.area_dc_clear = true;

  }

}

/* Do the LSA acking specified in table 19, Section 13.5, row 2

 * This get called from ospf_flood_out_interface. Declared inline

 * for speed. */

static void ospf_flood_delayed_lsa_ack(struct ospf_neighbor *inbr,

               struct ospf_lsa *lsa)

{

  /* LSA is more recent than database copy, but was not

     flooded back out receiving interface.  Delayed

     acknowledgment sent. If interface is in Backup state

     delayed acknowledgment sent only if advertisement

     received from Designated Router, otherwise do nothing See

     RFC 2328 Section 13.5 */

  /* Whether LSA is more recent or not, and whether this is in

     response to the LSA being sent out recieving interface has been

     worked out previously */

  /* Deal with router as BDR */

  if (inbr->oi->state == ISM_Backup && !NBR_IS_DR(inbr))

    return;

  /* Schedule a delayed LSA Ack to be sent */

  listnode_add(inbr->oi->ls_ack,

         ospf_lsa_lock(lsa)); /* delayed LSA Ack */

}

/* Check LSA is related to external info. */

struct external_info *ospf_external_info_check(struct ospf *ospf,

                 struct ospf_lsa *lsa)

{

  struct as_external_lsa *al;

  struct prefix_ipv4 p;

  struct route_node *rn;

  struct list *ext_list;

  struct listnode *node;

  struct ospf_external *ext;

  int type;

  al = (struct as_external_lsa *)lsa->data;

  p.family = AF_INET;

  p.prefix = lsa->data->id;

  p.prefixlen = ip_masklen(al->mask);

  for (type = 0; type < ZEBRA_ROUTE_MAX; type++) {

    int redist_on = 0;

    redist_on =

      is_default_prefix4(&p)

        ? vrf_bitmap_check(

          zclient->default_information[AFI_IP],

          ospf->vrf_id)

        : (zclient->mi_redist[AFI_IP][type].enabled

           || vrf_bitmap_check(

             zclient->redist[AFI_IP][type],

             ospf->vrf_id));

    // Pending: check for MI above.

    if (redist_on) {

      ext_list = ospf->external[type];

      if (!ext_list)

        continue;

      for (ALL_LIST_ELEMENTS_RO(ext_list, node, ext)) {

        rn = NULL;

        if (ext->external_info)

          rn = route_node_lookup(

            ext->external_info,

            (struct prefix *)&p);

        if (rn) {

          route_unlock_node(rn);

          if (rn->info != NULL)

            return (struct external_info *)

              rn->info;

        }

      }

    }

  }

  if (is_default_prefix4(&p) && ospf->external[DEFAULT_ROUTE]) {

    ext_list = ospf->external[DEFAULT_ROUTE];

    for (ALL_LIST_ELEMENTS_RO(ext_list, node, ext)) {

      if (!ext->external_info)

        continue;

      rn = route_node_lookup(ext->external_info,

                 (struct prefix *)&p);

      if (!rn)

        continue;

      route_unlock_node(rn);

      if (rn->info != NULL)

        return (struct external_info *)rn->info;

    }

  }

  return NULL;

}

static void ospf_process_self_originated_lsa(struct ospf *ospf,

               struct ospf_lsa *new,

               struct ospf_area *area)

{

  struct ospf_interface *oi;

  struct external_info *ei;

  struct listnode *node;

  struct as_external_lsa *al;

  struct prefix_ipv4 p;

  struct ospf_external_aggr_rt *aggr;

  if (IS_DEBUG_OSPF_EVENT)

    zlog_debug(

      "%s:LSA[Type%d:%pI4]: Process self-originated LSA seq 0x%x",

      ospf_get_name(ospf), new->data->type,

      &new->data->id, ntohl(new->data->ls_seqnum));

  /* If we're here, we installed a self-originated LSA that we received

     from a neighbor, i.e. it's more recent.  We must see whether we want

     to originate it.

     If yes, we should use this LSA's sequence number and reoriginate

     a new instance.

     if not --- we must flush this LSA from the domain. */

  switch (new->data->type) {

  case OSPF_ROUTER_LSA:

    /* Originate a new instance and schedule flooding */

    if (area->router_lsa_self)

      area->router_lsa_self->data->ls_seqnum =

        new->data->ls_seqnum;

    ospf_router_lsa_update_area(area);

    return;

  case OSPF_NETWORK_LSA:

  case OSPF_OPAQUE_LINK_LSA:

    /* We must find the interface the LSA could belong to.

       If the interface is no more a broadcast type or we are no

       more

       the DR, we flush the LSA otherwise -- create the new instance

       and

       schedule flooding. */

    /* Look through all interfaces, not just area, since interface

       could be moved from one area to another. */

    for (ALL_LIST_ELEMENTS_RO(ospf->oiflist, node, oi))

      /* These are sanity check. */

      if (IPV4_ADDR_SAME(&oi->address->u.prefix4,

             &new->data->id)) {

        if (oi->area != area

            || oi->type != OSPF_IFTYPE_BROADCAST

            || !IPV4_ADDR_SAME(&oi->address->u.prefix4,

                   &DR(oi))) {

          ospf_schedule_lsa_flush_area(area, new);

          return;

        }

        if (new->data->type == OSPF_OPAQUE_LINK_LSA) {

          ospf_opaque_lsa_refresh(new);

          return;

        }

        if (oi->network_lsa_self)

          oi->network_lsa_self->data->ls_seqnum =

            new->data->ls_seqnum;

        /* Schedule network-LSA origination. */

        ospf_network_lsa_update(oi);

        return;

      }

    break;

  case OSPF_SUMMARY_LSA:

  case OSPF_ASBR_SUMMARY_LSA:

    ospf_schedule_abr_task(ospf);

    break;

  case OSPF_AS_EXTERNAL_LSA:

  case OSPF_AS_NSSA_LSA:

    if ((new->data->type == OSPF_AS_EXTERNAL_LSA)

        && CHECK_FLAG(new->flags, OSPF_LSA_LOCAL_XLT)) {

      ospf_translated_nssa_refresh(ospf, NULL, new);

      return;

    }

    al = (struct as_external_lsa *)new->data;

    p.family = AF_INET;

    p.prefixlen = ip_masklen(al->mask);

    p.prefix = new->data->id;

    ei = ospf_external_info_check(ospf, new);

    if (ei) {

      if (ospf_external_aggr_match(ospf, &ei->p)) {

        if (IS_DEBUG_OSPF(lsa, EXTNL_LSA_AGGR))

          zlog_debug(

            "%s, Matching external aggregate route found for %pI4, so don't refresh it.",

            __func__,

            &ei->p.prefix);

        /* Aggregated external route shouldn't

         * be in LSDB.

         */

        if (!IS_LSA_MAXAGE(new))

          ospf_lsa_flush_as(ospf, new);

        return;

      }

      ospf_external_lsa_refresh(ospf, new, ei,

              LSA_REFRESH_FORCE, false);

    } else {

      aggr = (struct ospf_external_aggr_rt *)

        ospf_extrenal_aggregator_lookup(ospf, &p);

      if (aggr) {

        struct external_info ei_aggr;

        memset(&ei_aggr, 0,

          sizeof(struct external_info));

        ei_aggr.p = aggr->p;

        ei_aggr.tag = aggr->tag;

        ei_aggr.instance = ospf->instance;

        ei_aggr.route_map_set.metric = -1;

        ei_aggr.route_map_set.metric_type = -1;

        ospf_external_lsa_refresh(ospf, new, &ei_aggr,

              LSA_REFRESH_FORCE, true);

        SET_FLAG(aggr->flags,

           OSPF_EXTERNAL_AGGRT_ORIGINATED);

      } else

        ospf_lsa_flush_as(ospf, new);

    }

    break;

  case OSPF_OPAQUE_AREA_LSA:

    ospf_opaque_lsa_refresh(new);

    break;

  case OSPF_OPAQUE_AS_LSA:

    ospf_opaque_lsa_refresh(new);

    /* Reconsideration may needed. */ /* XXX */

    break;

  default:

    break;

  }

}

/* OSPF LSA flooding -- RFC2328 Section 13.(5). */

/* Now Updated for NSSA operation, as follows:

  Type-5's have no change.  Blocked to STUB or NSSA.

  Type-7's can be received, and if a DR

  they will also flood the local NSSA Area as Type-7's

  If a Self-Originated LSA (now an ASBR),

  The LSDB will be updated as Type-5's, (for continual re-fresh)

      If an NSSA-IR it is installed/flooded as Type-7, P-bit on.

      if an NSSA-ABR it is installed/flooded as Type-7, P-bit off.

  Later, during the ABR TASK, if the ABR is the Elected NSSA

  translator, then All Type-7s (with P-bit ON) are Translated to

  Type-5's and flooded to all non-NSSA/STUB areas.

  During ASE Calculations,

      non-ABRs calculate external routes from Type-7's

      ABRs calculate external routes from Type-5's and non-self Type-7s

*/

int ospf_flood(struct ospf *ospf, struct ospf_neighbor *nbr,

         struct ospf_lsa *current, struct ospf_lsa *new)

{

  struct ospf_interface *oi;

  int lsa_ack_flag;

  /* Type-7 LSA's will be flooded throughout their native NSSA area,

     but will also be flooded as Type-5's into ABR capable links.  */

  if (IS_DEBUG_OSPF_EVENT)

    zlog_debug(

      "%s:LSA[Flooding]: start, NBR %pI4 (%s), cur(%p), New-LSA[%s]",

      ospf_get_name(ospf), &nbr->router_id,

      lookup_msg(ospf_nsm_state_msg, nbr->state, NULL),

      (void *)current, dump_lsa_key(new));

  oi = nbr->oi;

  /* If there is already a database copy, and if the

     database copy was received via flooding and installed less

     than MinLSArrival seconds ago, discard the new LSA

     (without acknowledging it). */

  if (current != NULL) /* -- endo. */

  {

    if (IS_LSA_SELF(current)

        && (ntohs(current->data->ls_age) == 0

      && ntohl(current->data->ls_seqnum)

           == OSPF_INITIAL_SEQUENCE_NUMBER)) {

      if (IS_DEBUG_OSPF_EVENT)

        zlog_debug(

          "%s:LSA[Flooding]: Got a self-originated LSA, while local one is initial instance.",

          ospf_get_name(ospf));

      ; /* Accept this LSA for quick LSDB resynchronization.

           */

    } else if (monotime_since(&current->tv_recv, NULL)

         < ospf->min_ls_arrival * 1000LL) {

      if (IS_DEBUG_OSPF_EVENT)

        zlog_debug(

          "%s:LSA[Flooding]: LSA is received recently.",

          ospf_get_name(ospf));

      return -1;

    }

  }

  /* Flood the new LSA out some subset of the router's interfaces.

     In some cases (e.g., the state of the receiving interface is

     DR and the LSA was received from a router other than the

     Backup DR) the LSA will be flooded back out the receiving

     interface. */

  lsa_ack_flag = ospf_flood_through(ospf, nbr, new);

  /* Remove the current database copy from all neighbors' Link state

     retransmission lists.  AS_EXTERNAL and AS_EXTERNAL_OPAQUE does

                ^^^^^^^^^^^^^^^^^^^^^^^

     not have area ID.

     All other (even NSSA's) do have area ID.  */

  if (current) {

    switch (current->data->type) {

    case OSPF_AS_EXTERNAL_LSA:

    case OSPF_OPAQUE_AS_LSA:

      ospf_ls_retransmit_delete_nbr_as(ospf, current);

      break;

    default:

      ospf_ls_retransmit_delete_nbr_area(oi->area, current);

      break;

    }

  }

  /* Do some internal house keeping that is needed here */

  SET_FLAG(new->flags, OSPF_LSA_RECEIVED);

  (void)ospf_lsa_is_self_originated(ospf, new); /* Let it set the flag */

  /* Received non-self-originated Grace LSA */

  if (IS_GRACE_LSA(new) && !IS_LSA_SELF(new)) {

    if (IS_LSA_MAXAGE(new)) {

      /*  Handling Max age grace LSA.*/

      if (IS_DEBUG_OSPF_GR)

        zlog_debug(

          "%s, Received a maxage GRACE-LSA from router %pI4",

          __func__, &new->data->adv_router);

      if (current) {

        ospf_process_maxage_grace_lsa(ospf, new, nbr);

      } else {

        if (IS_DEBUG_OSPF_GR)

          zlog_debug(

            "%s, Grace LSA doesn't exist in lsdb, so discarding grace lsa",

            __func__);

        return -1;

      }

    } else {

      if (IS_DEBUG_OSPF_GR)

        zlog_debug(

          "%s, Received a GRACE-LSA from router %pI4",

          __func__, &new->data->adv_router);

      if (ospf_process_grace_lsa(ospf, new, nbr)

          == OSPF_GR_NOT_HELPER) {

        if (IS_DEBUG_OSPF_GR)

          zlog_debug(

            "%s, Not moving to HELPER role, So discarding grace LSA",

            __func__);

        return -1;

      }

    }

  }

  /* Install the new LSA in the link state database

     (replacing the current database copy).  This may cause the

     routing table calculation to be scheduled.  In addition,

     timestamp the new LSA with the current time.  The flooding

     procedure cannot overwrite the newly installed LSA until

     MinLSArrival seconds have elapsed. */

  if (!(new = ospf_lsa_install(ospf, oi, new)))

    return -1; /* unknown LSA type or any other error condition */

  /* check if the installed LSA is an indication LSA */

  if (ospf_check_indication_lsa(new) && !IS_LSA_SELF(new) &&

      !IS_LSA_MAXAGE(new)) {

    new->area->fr_info.area_ind_lsa_recvd = true;

    /* check if there are already type 5 LSAs originated

     * with DNA bit set, if yes reoriginate those LSAs.

     */

    ospf_refresh_dna_type5_and_type7_lsas(ospf);

  }

  /* Check if we recived an indication LSA flush on backbone

   * network.

   */

  ospf_recv_indication_lsa_flush(new);

  if (new->area && OSPF_FR_CONFIG(ospf, new->area)) {

    struct lsa_header const *lsah = new->data;

    if (!CHECK_FLAG(lsah->options, OSPF_OPTION_DC) &&

        !ospf_check_indication_lsa(new)) {

      new->area->fr_info.area_dc_clear = true;

      /* check of previously area supported flood reduction */

      if (new->area->fr_info.enabled) {

        new->area->fr_info.enabled = false;

        OSPF_LOG_DEBUG(

          IS_DEBUG_OSPF_EVENT,

          "Flood Reduction STATE on -> off by %s LSA",

          dump_lsa_key(new));

        /* if yes update all the lsa to the area the

         * new LSAs will have DNA bit set to 0.

         */

        ospf_refresh_area_self_lsas(new->area);

      }

    } else if (!new->area->fr_info.enabled) {

      /* check again after installing new LSA that area

       * supports flood reduction.

       */

      ospf_area_update_fr_state(new->area);

      if (new->area->fr_info.enabled) {

        OSPF_LOG_DEBUG(

          IS_DEBUG_OSPF_EVENT,

          "Flood Reduction STATE off -> on by %s LSA",

          dump_lsa_key(new));

        ospf_refresh_area_self_lsas(new->area);

      }

    }

  }

  /* Acknowledge the receipt of the LSA by sending a Link State

     Acknowledgment packet back out the receiving interface. */

  if (lsa_ack_flag)

    ospf_flood_delayed_lsa_ack(nbr, new);

  /* If this new LSA indicates that it was originated by the

     receiving router itself, the router must take special action,

     either updating the LSA or in some cases flushing it from

     the routing domain. */

  if (ospf_lsa_is_self_originated(ospf, new))

    ospf_process_self_originated_lsa(ospf, new, oi->area);

  else

    /* Update statistics value for OSPF-MIB. */

    ospf->rx_lsa_count++;

  return 0;

}

/* OSPF LSA flooding -- RFC2328 Section 13.3. */

int ospf_flood_through_interface(struct ospf_interface *oi,

         struct ospf_neighbor *inbr,

         struct ospf_lsa *lsa)

{

  struct ospf_neighbor *onbr;

  struct route_node *rn;

  int retx_flag;

  if (IS_DEBUG_OSPF_EVENT)

    zlog_debug(

      "%s: considering int %s (%s), INBR(%pI4), LSA[%s] AGE %u",

      __func__, IF_NAME(oi), ospf_get_name(oi->ospf),

      inbr ? &inbr->router_id : NULL, dump_lsa_key(lsa),

      ntohs(lsa->data->ls_age));

  if (!ospf_if_is_enable(oi))

    return 0;

  /* If flood reduction is configured, set the DC bit on the lsa. */

  if (IS_LSA_SELF(lsa)) {

    if (OSPF_FR_CONFIG(oi->area->ospf, oi->area)) {

      if (!ospf_check_indication_lsa(lsa)) {

        SET_FLAG(lsa->data->options, OSPF_OPTION_DC);

        ospf_lsa_checksum(lsa->data);

      }

    } else if (CHECK_FLAG(lsa->data->options, OSPF_OPTION_DC)) {

      UNSET_FLAG(lsa->data->options, OSPF_OPTION_DC);

      ospf_lsa_checksum(lsa->data);

    }

    /* If flood reduction is enabled then set DNA bit on the

     * self lsas.

     */

    if (oi->area->fr_info.enabled)

      SET_FLAG(lsa->data->ls_age, DO_NOT_AGE);

  }

  /* Remember if new LSA is added to a retransmit list. */

  retx_flag = 0;

  /* Each of the neighbors attached to this interface are examined,

     to determine whether they must receive the new LSA.  The following

     steps are executed for each neighbor: */

  for (rn = route_top(oi->nbrs); rn; rn = route_next(rn)) {

    struct ospf_lsa *ls_req;

    if (rn->info == NULL)

      continue;

    onbr = rn->info;

    if (IS_DEBUG_OSPF_EVENT)

      zlog_debug(

        "%s: considering nbr %pI4 via %s (%s), state: %s",

        __func__, &onbr->router_id, IF_NAME(oi),

        ospf_get_name(oi->ospf),

        lookup_msg(ospf_nsm_state_msg, onbr->state,

             NULL));

    /* If the neighbor is in a lesser state than Exchange, it

       does not participate in flooding, and the next neighbor

       should be examined. */

    if (onbr->state < NSM_Exchange)

      continue;

    /* If the adjacency is not yet full (neighbor state is

       Exchange or Loading), examine the Link state request

       list associated with this adjacency.  If there is an

       instance of the new LSA on the list, it indicates that

       the neighboring router has an instance of the LSA

       already.  Compare the new LSA to the neighbor's copy: */

    if (onbr->state < NSM_Full) {

      if (IS_DEBUG_OSPF_EVENT)

        zlog_debug(

          "%s: adj to onbr %pI4 is not Full (%s)",

          __func__, &onbr->router_id,

          lookup_msg(ospf_nsm_state_msg,

               onbr->state, NULL));

      ls_req = ospf_ls_request_lookup(onbr, lsa);

      if (ls_req != NULL) {

        int ret;

        ret = ospf_lsa_more_recent(ls_req, lsa);

        /* The new LSA is less recent. */

        if (ret > 0)

          continue;

        /* The two copies are the same instance, then

           delete

           the LSA from the Link state request list. */

        else if (ret == 0) {

          ospf_ls_request_delete(onbr, ls_req);

          ospf_check_nbr_loading(onbr);

          continue;

        }

        /* The new LSA is more recent.  Delete the LSA

           from the Link state request list. */

        else {

          ospf_ls_request_delete(onbr, ls_req);

          ospf_check_nbr_loading(onbr);

        }

      }

    }

    if (IS_OPAQUE_LSA(lsa->data->type)) {

      if (!CHECK_FLAG(onbr->options, OSPF_OPTION_O)) {

        if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

          zlog_debug(

            "%s: Skipping neighbor %s via %pI4 -- Not Opaque-capable.",

            __func__, IF_NAME(oi),

            &onbr->router_id);

        continue;

      }

    }

 /* If the new LSA was received from this neighbor,

    examine the next neighbor. */

    if (inbr) {

      /*

       * Triggered by LSUpd message parser "ospf_ls_upd ()".

       * E.g., all LSAs handling here is received via network.

       */

      if (IPV4_ADDR_SAME(&inbr->router_id,

             &onbr->router_id)) {

        if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

          zlog_debug(

            "%s: Skipping neighbor %s via %pI4 -- inbr == onbr.",

            __func__, IF_NAME(oi),

            &inbr->router_id);

        continue;

      }

    } else {

      /*

       * Triggered by MaxAge remover, so far.

       * NULL "inbr" means flooding starts from this node.

       */

      if (IPV4_ADDR_SAME(&lsa->data->adv_router,

             &onbr->router_id)) {

        if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

          zlog_debug(

            "%s: Skipping neighbor %s via %pI4 -- lsah->adv_router == onbr.",

            __func__, IF_NAME(oi),

            &onbr->router_id);

        continue;

      }

    }

    /* Add the new LSA to the Link state retransmission list

       for the adjacency. The LSA will be retransmitted

       at intervals until an acknowledgment is seen from

       the neighbor. */

    ospf_ls_retransmit_add(onbr, lsa);

    retx_flag = 1;

  }

  /* If in the previous step, the LSA was NOT added to any of

     the Link state retransmission lists, there is no need to

     flood the LSA out the interface. */

  if (retx_flag == 0) {

    return (inbr && inbr->oi == oi);

  }

  /* if we've received the lsa on this interface we need to perform

     additional checking */

  if (inbr && (inbr->oi == oi)) {

    /* If the new LSA was received on this interface, and it was

       received from either the Designated Router or the Backup

       Designated Router, chances are that all the neighbors have

       received the LSA already. */

    if (NBR_IS_DR(inbr) || NBR_IS_BDR(inbr)) {

      if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

        zlog_debug("%s: DR/BDR NOT SEND to int %s (%s)",

             __func__, IF_NAME(oi),

             ospf_get_name(oi->ospf));

      return 1;

    }

    /* If the new LSA was received on this interface, and the

       interface state is Backup, examine the next interface.  The

       Designated Router will do the flooding on this interface.

       However, if the Designated Router fails the router will

       end up retransmitting the updates. */

    if (oi->state == ISM_Backup) {

      if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

        zlog_debug(

          "%s: ISM_Backup NOT SEND to int %s (%s)",

          __func__, IF_NAME(oi),

          ospf_get_name(oi->ospf));

      return 1;

    }

  }

  /* The LSA must be flooded out the interface. Send a Link State

     Update packet (including the new LSA as contents) out the

     interface.  The LSA's LS age must be incremented by InfTransDelay

     (which must be > 0) when it is copied into the outgoing Link

     State Update packet (until the LS age field reaches the maximum

     value of MaxAge). */

  if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

    zlog_debug("%s: DR/BDR sending upd to int %s (%s)", __func__,

         IF_NAME(oi), ospf_get_name(oi->ospf));

  /*  RFC2328  Section 13.3

      On non-broadcast networks, separate Link State Update

      packets must be sent, as unicasts, to each adjacent neighbor

      (i.e., those in state Exchange or greater).  The destination

      IP addresses for these packets are the neighbors' IP

      addresses.   */

  if (oi->type == OSPF_IFTYPE_NBMA) {

    struct ospf_neighbor *nbr;

    for (rn = route_top(oi->nbrs); rn; rn = route_next(rn)) {

      nbr = rn->info;

      if (!nbr)

        continue;

      if (nbr != oi->nbr_self && nbr->state >= NSM_Exchange)

        ospf_ls_upd_send_lsa(nbr, lsa,

                 OSPF_SEND_PACKET_DIRECT);

    }

  } else

    /* If P2MP delayed reflooding is configured and the LSA was

       received from a neighbor on the P2MP interface, do not flood

       if back out on the interface. The LSA will be  retransmitted

       upon expiration of each neighbor's retransmission timer. This

       will allow time to receive a multicast multicast link state

       acknoweldgement and remove the LSA from each neighbor's link

       state retransmission list. */

    if (oi->p2mp_delay_reflood &&

        (oi->type == OSPF_IFTYPE_POINTOMULTIPOINT) &&

        (inbr != NULL) && (oi == inbr->oi)) {

      if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

        zlog_debug(

          "Delay reflooding for LSA[%s] from NBR %pI4 on interface %s",

          dump_lsa_key(lsa),

          inbr ? &(inbr->router_id)

               : &(oi->ospf->router_id),

          IF_NAME(oi));

    } else

      ospf_ls_upd_send_lsa(oi->nbr_self, lsa,

               OSPF_SEND_PACKET_INDIRECT);

  return 0;

}

int ospf_flood_through_area(struct ospf_area *area, struct ospf_neighbor *inbr,

          struct ospf_lsa *lsa)

{

  struct listnode *node, *nnode;

  struct ospf_interface *oi;

  int lsa_ack_flag = 0;

  assert(area);

  /* All other types are specific to a single area (Area A).  The

     eligible interfaces are all those interfaces attaching to the

     Area A.  If Area A is the backbone, this includes all the virtual

     links.  */

  for (ALL_LIST_ELEMENTS(area->oiflist, node, nnode, oi)) {

    if (area->area_id.s_addr != OSPF_AREA_BACKBONE

        && oi->type == OSPF_IFTYPE_VIRTUALLINK)

      continue;

    if ((lsa->data->type == OSPF_OPAQUE_LINK_LSA)

        && (lsa->oi != oi)) {

      /*

       * Link local scoped Opaque-LSA should only be flooded

       * for the link on which the LSA has received.

       */

      if (IS_DEBUG_OSPF(lsa, LSA_FLOODING))

        zlog_debug(

          "Type-9 Opaque-LSA: lsa->oi(%p) != oi(%p)",

          (void *)lsa->oi, (void *)oi);

      continue;

    }

    if (ospf_flood_through_interface(oi, inbr, lsa))

      lsa_ack_flag = 1;

  }

  return (lsa_ack_flag);

}

int ospf_flood_through_as(struct ospf *ospf, struct ospf_neighbor *inbr,

        struct ospf_lsa *lsa)

{

  struct listnode *node;

  struct ospf_area *area;

  int lsa_ack_flag;

  lsa_ack_flag = 0;

  /* The incoming LSA is type 5 or type 7  (AS-EXTERNAL or AS-NSSA )

    Divert the Type-5 LSA's to all non-NSSA/STUB areas

    Divert the Type-7 LSA's to all NSSA areas

     AS-external-LSAs are flooded throughout the entire AS, with the

     exception of stub areas (see Section 3.6).  The eligible

     interfaces are all the router's interfaces, excluding virtual

     links and those interfaces attaching to stub areas.  */

  if (CHECK_FLAG(lsa->flags, OSPF_LSA_LOCAL_XLT)) /* Translated from 7  */

    if (IS_DEBUG_OSPF_NSSA)

      zlog_debug("Flood/AS: NSSA TRANSLATED LSA");

  for (ALL_LIST_ELEMENTS_RO(ospf->areas, node, area)) {

    int continue_flag = 0;

    struct listnode *if_node;

    struct ospf_interface *oi;

    switch (area->external_routing) {

    /* Don't send AS externals into stub areas.  Various types

       of support for partial stub areas can be implemented

       here.  NSSA's will receive Type-7's that have areas

       matching the originl LSA. */

    case OSPF_AREA_NSSA: /* Sending Type 5 or 7 into NSSA area */

             /* Type-7, flood NSSA area */

      if (lsa->data->type == OSPF_AS_NSSA_LSA

          && area == lsa->area)

        /* We will send it. */

        continue_flag = 0;

      else

        continue_flag = 1; /* Skip this NSSA area for

                  Type-5's et al */

      break;

    case OSPF_AREA_TYPE_MAX:

    case OSPF_AREA_STUB:

      continue_flag = 1; /* Skip this area. */

      break;

    case OSPF_AREA_DEFAULT:

    default:

      /* No Type-7 into normal area */

      if (lsa->data->type == OSPF_AS_NSSA_LSA)

        continue_flag = 1; /* skip Type-7 */

      else

        continue_flag = 0; /* Do this area. */

      break;

    }

    /* Do continue for above switch.  Saves a big if then mess */

    if (continue_flag)

      continue; /* main for-loop */

    /* send to every interface in this area */

    for (ALL_LIST_ELEMENTS_RO(area->oiflist, if_node, oi)) {

      /* Skip virtual links */

      if (oi->type != OSPF_IFTYPE_VIRTUALLINK)

        if (ospf_flood_through_interface(oi, inbr,

                 lsa)) /* lsa */

          lsa_ack_flag = 1;

    }

  } /* main area for-loop */

  return (lsa_ack_flag);

}

int ospf_flood_through(struct ospf *ospf, struct ospf_neighbor *inbr,

           struct ospf_lsa *lsa)

{

  int lsa_ack_flag = 0;

  /* Type-7 LSA's for NSSA are flooded throughout the AS here, and

     upon return are updated in the LSDB for Type-7's.  Later,

     re-fresh will re-send them (and also, if ABR, packet code will

     translate to Type-5's)

     As usual, Type-5 LSA's (if not DISCARDED because we are STUB or

     NSSA) are flooded throughout the AS, and are updated in the

     global table.  */

  /*

   * At the common sub-sub-function "ospf_flood_through_interface()",

   * a parameter "inbr" will be used to distinguish the called context

   * whether the given LSA was received from the neighbor, or the

   * flooding for the LSA starts from this node (e.g. the LSA was self-

   * originated, or the LSA is going to be flushed from routing domain).

   *

   * So, for consistency reasons, this function "ospf_flood_through()"

   * should also allow the usage that the given "inbr" parameter to be

   * NULL. If we do so, corresponding AREA parameter should be referred

   * by "lsa->area", instead of "inbr->oi->area".

   */

  switch (lsa->data->type) {

  case OSPF_AS_EXTERNAL_LSA: /* Type-5 */

  case OSPF_OPAQUE_AS_LSA:

    lsa_ack_flag = ospf_flood_through_as(ospf, inbr, lsa);

    break;

  /* Type-7 Only received within NSSA, then flooded */

  case OSPF_AS_NSSA_LSA:

    /* Any P-bit was installed with the Type-7. */

    if (IS_DEBUG_OSPF_NSSA)

      zlog_debug("%s: LOCAL NSSA FLOOD of Type-7.", __func__);

  /* Fallthrough */

  default:

    lsa_ack_flag = ospf_flood_through_area(lsa->area, inbr, lsa);