ospf_ism.c

router source code for the ospdf.

      OSPF_ISM_TIMER_OFF (oi->t_wait);
      OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
      break;
    case ISM_Waiting:
      /* The router is trying to determine the identity of DRouter and
	 BDRouter. The router begin to receive and send Hello Packets. */
      /* send first hello immediately */
      OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer, 1);
      OSPF_ISM_TIMER_ON (oi->t_wait, ospf_wait_timer,
			 OSPF_IF_PARAM (oi, v_wait));
      OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
      break;
    case ISM_PointToPoint:
      /* The interface connects to a physical Point-to-point network or
	 virtual link. The router attempts to form an adjacency with
	 neighboring router. Hello packets are also sent. */
      /* send first hello immediately */
      OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer, 1);
      
      OSPF_ISM_TIMER_OFF (oi->t_wait);
      OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
      break;
    case ISM_DROther:
      /* The network type of the interface is broadcast or NBMA network,
	 and the router itself is neither Designated Router nor
	 Backup Designated Router. */
      OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
			 OSPF_IF_PARAM (oi, v_hello));
      OSPF_ISM_TIMER_OFF (oi->t_wait);
      OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
      break;
    case ISM_Backup:
      /* The network type of the interface is broadcast os NBMA network,
	 and the router is Backup Designated Router. */
      OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
			 OSPF_IF_PARAM (oi, v_hello));
      OSPF_ISM_TIMER_OFF (oi->t_wait);
      OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
      break;
    case ISM_DR:
      /* The network type of the interface is broadcast or NBMA network,
	 and the router is Designated Router. */
      OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
			 OSPF_IF_PARAM (oi, v_hello));
      OSPF_ISM_TIMER_OFF (oi->t_wait);
      OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
      break;
    }
}

int
ism_stop (struct ospf_interface *oi)
{
  return 0;
}

int
ism_interface_up (struct ospf_interface *oi)
{
  int next_state = 0;

  /* if network type is point-to-point, Point-to-MultiPoint or virtual link,
     the state transitions to Point-to-Point. */
  if (oi->type == OSPF_IFTYPE_POINTOPOINT ||
      oi->type == OSPF_IFTYPE_POINTOMULTIPOINT ||
      oi->type == OSPF_IFTYPE_VIRTUALLINK)
    next_state = ISM_PointToPoint;
  /* Else if the router is not eligible to DR, the state transitions to
     DROther. */
  else if (PRIORITY (oi) == 0) /* router is eligible? */
    next_state = ISM_DROther;
  else
    /* Otherwise, the state transitions to Waiting. */
    next_state = ISM_Waiting;

  if (oi->type == OSPF_IFTYPE_NBMA)
    ospf_nbr_nbma_if_update (oi->ospf, oi);

  /*  ospf_ism_event (t); */
  return next_state;
}

int
ism_loop_ind (struct ospf_interface *oi)
{
  int ret = 0;

  /* call ism_interface_down. */
  /* ret = ism_interface_down (oi); */

  return ret;
}

/* Interface down event handler. */
int
ism_interface_down (struct ospf_interface *oi)
{
  ospf_if_cleanup (oi);
  return 0;
}


int
ism_backup_seen (struct ospf_interface *oi)
{
  return ospf_dr_election (oi);
}

int
ism_wait_timer (struct ospf_interface *oi)
{
  return ospf_dr_election (oi);
}

int
ism_neighbor_change (struct ospf_interface *oi)
{
  return ospf_dr_election (oi);
}

int
ism_ignore (struct ospf_interface *oi)
{
  if (IS_DEBUG_OSPF (ism, ISM_EVENTS))
    zlog (NULL, LOG_INFO, "ISM[%s]: ism_ignore called", IF_NAME (oi));

  return 0;
}

/* Interface State Machine */
struct {
  int (*func) ();
  int next_state;
} ISM [OSPF_ISM_STATE_MAX][OSPF_ISM_EVENT_MAX] =
{
  {
    /* DependUpon: dummy state. */
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_ignore,          ISM_DependUpon },    /* InterfaceUp    */
    { ism_ignore,          ISM_DependUpon },    /* WaitTimer      */
    { ism_ignore,          ISM_DependUpon },    /* BackupSeen     */
    { ism_ignore,          ISM_DependUpon },    /* NeighborChange */
    { ism_ignore,          ISM_DependUpon },    /* LoopInd        */
    { ism_ignore,          ISM_DependUpon },    /* UnloopInd      */
    { ism_ignore,          ISM_DependUpon },    /* InterfaceDown  */
  },
  {
    /* Down:*/
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_interface_up,    ISM_DependUpon },    /* InterfaceUp    */
    { ism_ignore,          ISM_Down },          /* WaitTimer      */
    { ism_ignore,          ISM_Down },          /* BackupSeen     */
    { ism_ignore,          ISM_Down },          /* NeighborChange */
    { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
    { ism_ignore,          ISM_Down },          /* UnloopInd      */
    { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
  },
  {
    /* Loopback: */
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_ignore,          ISM_Loopback },      /* InterfaceUp    */
    { ism_ignore,          ISM_Loopback },      /* WaitTimer      */
    { ism_ignore,          ISM_Loopback },      /* BackupSeen     */
    { ism_ignore,          ISM_Loopback },      /* NeighborChange */
    { ism_ignore,          ISM_Loopback },      /* LoopInd        */
    { ism_ignore,          ISM_Down },          /* UnloopInd      */
    { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
  },
  {
    /* Waiting: */
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_ignore,          ISM_Waiting },       /* InterfaceUp    */
    { ism_wait_timer,	   ISM_DependUpon },    /* WaitTimer      */
    { ism_backup_seen,     ISM_DependUpon },    /* BackupSeen     */
    { ism_ignore,          ISM_Waiting },       /* NeighborChange */
    { ism_loop_ind,	   ISM_Loopback },      /* LoopInd        */
    { ism_ignore,          ISM_Waiting },       /* UnloopInd      */
    { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
  },
  {
    /* Point-to-Point: */
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_ignore,          ISM_PointToPoint },  /* InterfaceUp    */
    { ism_ignore,          ISM_PointToPoint },  /* WaitTimer      */
    { ism_ignore,          ISM_PointToPoint },  /* BackupSeen     */
    { ism_ignore,          ISM_PointToPoint },  /* NeighborChange */
    { ism_loop_ind,	   ISM_Loopback },      /* LoopInd        */
    { ism_ignore,          ISM_PointToPoint },  /* UnloopInd      */
    { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
  },
  {
    /* DROther: */
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_ignore,          ISM_DROther },       /* InterfaceUp    */
    { ism_ignore,          ISM_DROther },       /* WaitTimer      */
    { ism_ignore,          ISM_DROther },       /* BackupSeen     */
    { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
    { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
    { ism_ignore,          ISM_DROther },       /* UnloopInd      */
    { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
  },
  {
    /* Backup: */
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_ignore,          ISM_Backup },        /* InterfaceUp    */
    { ism_ignore,          ISM_Backup },        /* WaitTimer      */
    { ism_ignore,          ISM_Backup },        /* BackupSeen     */
    { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
    { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
    { ism_ignore,          ISM_Backup },        /* UnloopInd      */
    { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
  },
  {
    /* DR: */
    { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
    { ism_ignore,          ISM_DR },            /* InterfaceUp    */
    { ism_ignore,          ISM_DR },            /* WaitTimer      */
    { ism_ignore,          ISM_DR },            /* BackupSeen     */
    { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
    { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
    { ism_ignore,          ISM_DR },            /* UnloopInd      */
    { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
  },
};  

static char *ospf_ism_event_str[] =
{
  "NoEvent",
  "InterfaceUp",
  "WaitTimer",
  "BackupSeen",
  "NeighborChange",
  "LoopInd",
  "UnLoopInd",
  "InterfaceDown",
};

void
ism_change_state (struct ospf_interface *oi, int state)
{
  int old_state;
  struct ospf_lsa *lsa;

  /* Logging change of state. */
  if (IS_DEBUG_OSPF (ism, ISM_STATUS))
    zlog (NULL, LOG_INFO, "ISM[%s]: State change %s -> %s", IF_NAME (oi),
	  LOOKUP (ospf_ism_state_msg, oi->state),
	  LOOKUP (ospf_ism_state_msg, state));

  old_state = oi->state;
  oi->state = state;
  oi->state_change++;

  if (old_state == ISM_Down || state == ISM_Down)
    ospf_check_abr_status (oi->ospf);

  /* Originate router-LSA. */
  if (oi->area)
    {
      if (state == ISM_Down)
	{
	  if (oi->area->act_ints > 0)
	    oi->area->act_ints--;
	}
      else if (old_state == ISM_Down)
	oi->area->act_ints++;

      /* schedule router-LSA originate. */
      ospf_router_lsa_timer_add (oi->area);
    }

  /* Originate network-LSA. */
  if (old_state != ISM_DR && state == ISM_DR)
    ospf_network_lsa_timer_add (oi);
  else if (old_state == ISM_DR && state != ISM_DR)
    {
      /* Free self originated network LSA. */
      lsa = oi->network_lsa_self;
      if (lsa)
	{
	  ospf_lsa_flush_area (lsa, oi->area);
	  OSPF_TIMER_OFF (oi->t_network_lsa_self);
	}

      ospf_lsa_unlock (oi->network_lsa_self);
      oi->network_lsa_self = NULL;
    }

#ifdef HAVE_OPAQUE_LSA
  ospf_opaque_ism_change (oi, old_state);
#endif /* HAVE_OPAQUE_LSA */

  /* Check area border status.  */
  ospf_check_abr_status (oi->ospf);
}

/* Execute ISM event process. */
int
ospf_ism_event (struct thread *thread)
{
  int event;
  int next_state;
  struct ospf_interface *oi;

  oi = THREAD_ARG (thread);
  event = THREAD_VAL (thread);

  /* Call function. */
  next_state = (*(ISM [oi->state][event].func))(oi);

  if (! next_state)
    next_state = ISM [oi->state][event].next_state;

  if (IS_DEBUG_OSPF (ism, ISM_EVENTS))
    zlog (NULL, LOG_INFO, "ISM[%s]: %s (%s)", IF_NAME (oi),
	  LOOKUP (ospf_ism_state_msg, oi->state),
	  ospf_ism_event_str[event]);

  /* If state is changed. */
  if (next_state != oi->state)
    ism_change_state (oi, next_state);

  /* Make sure timer is set. */
  ism_timer_set (oi);

  return 0;
}