ospf6_flood.c

linux 路由软件 可支持RIP OSPF BGP等

    ospf6_acknowledge_lsa_bdrouter (lsa, ismore_recent, from);
  else
    ospf6_acknowledge_lsa_allother (lsa, ismore_recent, from);
}

/* RFC2328 section 13 (4):
   if MaxAge LSA and if we have no instance, and no neighbor
   is in states Exchange or Loading
   returns 1 if match this case, else returns 0 */
static int
ospf6_is_maxage_lsa_drop (struct ospf6_lsa *lsa, struct ospf6_neighbor *from)
{
  struct ospf6_neighbor *on;
  struct ospf6_interface *oi;
  struct ospf6_area *oa;
  struct ospf6 *process = NULL;
  listnode i, j, k;
  int count = 0;

  if (! OSPF6_LSA_IS_MAXAGE (lsa))
    return 0;

  if (ospf6_lsdb_lookup (lsa->header->type, lsa->header->id,
                         lsa->header->adv_router, lsa->lsdb))
    return 0;

  process = from->ospf6_if->area->ospf6;
  for (i = listhead (process->area_list); i; nextnode (i))
    {
      oa = OSPF6_AREA (getdata (i));
      for (j = listhead (oa->if_list); j; nextnode (j))
        {
          oi = OSPF6_INTERFACE (getdata (j));
          for (k = listhead (oi->neighbor_list); k; nextnode (k))
            {
              on = OSPF6_NEIGHBOR (getdata (k));
              if (on->state == OSPF6_NEIGHBOR_EXCHANGE ||
                  on->state == OSPF6_NEIGHBOR_LOADING)
                count++;
            }
        }
    }

  if (count == 0)
    return 1;
  return 0;
}

/* RFC2328 section 13 The Flooding Procedure */
void
ospf6_receive_lsa (struct ospf6_neighbor *from,
                   struct ospf6_lsa_header *lsa_header)
{
  struct ospf6_lsa *new = NULL, *old = NULL, *rem = NULL;
  int ismore_recent;
  unsigned short cksum;
  int is_debug = 0;

  ismore_recent = 1;
  assert (from);

  /* make lsa structure for received lsa */
  new = ospf6_lsa_create (lsa_header);

  if (IS_OSPF6_DEBUG_FLOODING ||
      IS_OSPF6_DEBUG_FLOOD_TYPE (new->header->type))
    {
      is_debug++;
      zlog_info ("LSA Receive from %s", from->name);
      ospf6_lsa_header_print (new);
    }

  /* (1) LSA Checksum */
  cksum = ntohs (new->header->checksum);
  if (ntohs (ospf6_lsa_checksum (new->header)) != cksum)
    {
      if (is_debug)
        zlog_info ("Wrong LSA Checksum, discard");
      ospf6_lsa_delete (new);
      return;
    }

  /* (2) Examine the LSA's LS type. 
     RFC2470 3.5.1. Receiving Link State Update packets  */
  if (IS_AREA_STUB (from->ospf6_if->area) &&
      OSPF6_LSA_SCOPE (new->header->type) == OSPF6_SCOPE_AS)
    {
      if (is_debug)
        zlog_info ("AS-External-LSA (or AS-scope LSA) in stub area, discard");
      ospf6_lsa_delete (new);
      return;
    }

  /* (3) LSA which have reserved scope is discarded
     RFC2470 3.5.1. Receiving Link State Update packets  */
  /* Flooding scope check. LSAs with unknown scope are discarded here.
     Set appropriate LSDB for the LSA */
  switch (OSPF6_LSA_SCOPE (new->header->type))
    {
    case OSPF6_SCOPE_LINKLOCAL:
      new->lsdb = from->ospf6_if->lsdb;
      break;
    case OSPF6_SCOPE_AREA:
      new->lsdb = from->ospf6_if->area->lsdb;
      break;
    case OSPF6_SCOPE_AS:
      new->lsdb = from->ospf6_if->area->ospf6->lsdb;
      break;
    default:
      if (is_debug)
        zlog_info ("LSA has reserved scope, discard");
      ospf6_lsa_delete (new);
      return;
    }

  /* (4) if MaxAge LSA and if we have no instance, and no neighbor
         is in states Exchange or Loading */
  if (ospf6_is_maxage_lsa_drop (new, from))
    {
      /* log */
      if (is_debug)
        zlog_info ("Drop MaxAge LSA with direct acknowledgement.");

      /* a) Acknowledge back to neighbor (Direct acknowledgement, 13.5) */
      ospf6_lsdb_add (ospf6_lsa_copy (new), from->lsack_list);
      if (from->thread_send_lsack == NULL)
        from->thread_send_lsack =
          thread_add_event (master, ospf6_lsack_send_neighbor, from, 0);

      /* b) Discard */
      ospf6_lsa_delete (new);
      return;
    }

  /* (5) */
  /* lookup the same database copy in lsdb */
  old = ospf6_lsdb_lookup (new->header->type, new->header->id,
                           new->header->adv_router, new->lsdb);
  if (old)
    {
      ismore_recent = ospf6_lsa_compare (new, old);
      if (ntohl (new->header->seqnum) == ntohl (old->header->seqnum))
        {
          if (is_debug)
            zlog_info ("Received is duplicated LSA");
          SET_FLAG (new->flag, OSPF6_LSA_DUPLICATE);
        }
    }

  /* if no database copy or received is more recent */
  if (old == NULL || ismore_recent < 0)
    {
      /* in case we have no database copy */
      ismore_recent = -1;

      /* (a) MinLSArrival check */
      if (old)
        {
          struct timeval now, res;
          gettimeofday (&now, (struct timezone *) NULL);
          timersub (&now, &old->installed, &res);
          if (res.tv_sec < MIN_LS_ARRIVAL)
            {
              if (is_debug)
                zlog_info ("LSA can't be updated within MinLSArrival, discard");
              ospf6_lsa_delete (new);
              return;   /* examin next lsa */
            }
        }

      gettimeofday (&new->received, (struct timezone *) NULL);

      if (is_debug)
        zlog_info ("Flood, Install, Possibly acknowledge the received LSA");

      /* (b) immediately flood and (c) remove from all retrans-list */
      /* Prevent self-originated LSA to be flooded. this is to make
      reoriginated instance of the LSA not to be rejected by other routers
      due to MinLSArrival. */
      if (new->header->adv_router != from->ospf6_if->area->ospf6->router_id)
        ospf6_flood (from, new);

      /* (c) Remove the current database copy from all neighbors' Link
             state retransmission lists. */
      /* XXX, flood_clear ? */

      /* (d), installing lsdb, which may cause routing
              table calculation (replacing database copy) */
      ospf6_install_lsa (new);

      /* (e) possibly acknowledge */
      ospf6_acknowledge_lsa (new, ismore_recent, from);

      /* (f) Self Originated LSA, section 13.4 */
      if (new->header->adv_router == from->ospf6_if->area->ospf6->router_id)
        {
          /* Self-originated LSA (newer than ours) is received from
             another router. We have to make a new instance of the LSA
             or have to flush this LSA. */
          if (is_debug)
            {
              zlog_info ("Newer instance of the self-originated LSA");
              zlog_info ("Schedule reorigination");
            }
          new->refresh = thread_add_event (master, ospf6_lsa_refresh, new, 0);
        }

      return;
    }

  /* (6) if there is instance on sending neighbor's request list */
  if (ospf6_lsdb_lookup (new->header->type, new->header->id,
                         new->header->adv_router, from->request_list))
    {
      /* if no database copy, should go above state (5) */
      assert (old);

      if (is_debug)
        {
          zlog_info ("Received is not newer, on the neighbor's request-list");
          zlog_info ("BadLSReq, discard the received LSA");
        }

      /* BadLSReq */
      thread_add_event (master, bad_lsreq, from, 0);

      ospf6_lsa_delete (new);
      return;
    }

  /* (7) if neither one is more recent */
  if (ismore_recent == 0)
    {
      if (is_debug)
        zlog_info ("The same instance as database copy (neither recent)");

      /* (a) if on retrans-list, Treat this LSA as an Ack: Implied Ack */
      rem = ospf6_lsdb_lookup (new->header->type, new->header->id,
                               new->header->adv_router, from->retrans_list);
      if (rem)
        {
          if (is_debug)
            {
              zlog_info ("It is on the neighbor's retrans-list.");
              zlog_info ("Treat as an Implied acknowledgement");
            }
          SET_FLAG (new->flag, OSPF6_LSA_IMPLIEDACK);
          ospf6_decrement_retrans_count (rem);
          ospf6_lsdb_remove (rem, from->retrans_list);
        }

      if (is_debug)
        zlog_info ("Possibly acknowledge and then discard");

      /* (b) possibly acknowledge */
      ospf6_acknowledge_lsa (new, ismore_recent, from);

      ospf6_lsa_delete (new);
      return;
    }

  /* (8) previous database copy is more recent */
    {
      assert (old);

      /* If database copy is in 'Seqnumber Wrapping',
         simply discard the received LSA */
      if (OSPF6_LSA_IS_MAXAGE (old) &&
          old->header->seqnum == htonl (MAX_SEQUENCE_NUMBER))
        {
          if (is_debug)
            {
              zlog_info ("The LSA is in Seqnumber Wrapping");
              zlog_info ("MaxAge & MaxSeqNum, discard");
            }
          ospf6_lsa_delete (new);
          return;
        }

      /* Otherwise, Send database copy of this LSA to this neighbor */
        {
          if (is_debug)
            {
              zlog_info ("Database copy is more recent.");
              zlog_info ("Send back directly and then discard");
            }

          /* XXX, MinLSArrival check !? RFC 2328 13 (8) */

          ospf6_lsdb_add (ospf6_lsa_copy (old), from->lsupdate_list);
          if (from->thread_send_lsupdate == NULL)
            from->thread_send_lsupdate =
              thread_add_event (master, ospf6_lsupdate_send_neighbor, from, 0);
          ospf6_lsa_delete (new);
          return;
        }
      return;
    }
}


DEFUN (debug_ospf6_flooding,
       debug_ospf6_flooding_cmd,
       "debug ospf6 flooding",
       DEBUG_STR
       OSPF6_STR
       "Debug OSPFv3 flooding function\n"
      )
{
  OSPF6_DEBUG_FLOODING_ON ();
  return CMD_SUCCESS;
}

DEFUN (no_debug_ospf6_flooding,
       no_debug_ospf6_flooding_cmd,
       "no debug ospf6 flooding",
       NO_STR
       DEBUG_STR
       OSPF6_STR
       "Debug OSPFv3 flooding function\n"
      )
{
  OSPF6_DEBUG_FLOODING_OFF ();
  return CMD_SUCCESS;
}

int
config_write_ospf6_debug_flood (struct vty *vty)
{
  if (IS_OSPF6_DEBUG_FLOODING)
    vty_out (vty, "debug ospf6 flooding%s", VNL);
  return 0;
}

void
install_element_ospf6_debug_flood ()
{
  install_element (ENABLE_NODE, &debug_ospf6_flooding_cmd);
  install_element (ENABLE_NODE, &no_debug_ospf6_flooding_cmd);
  install_element (CONFIG_NODE, &debug_ospf6_flooding_cmd);
  install_element (CONFIG_NODE, &no_debug_ospf6_flooding_cmd);
}