ospfd/ospf_ism.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * OSPF version 2  Interface State Machine
   4  *   From RFC2328 [OSPF Version 2]
   5  * Copyright (C) 1999, 2000 Toshiaki Takada
   6  */
   7
   8 #include <zebra.h>
   9
  10 #include "thread.h"
  11 #include "linklist.h"
  12 #include "prefix.h"
  13 #include "if.h"
  14 #include "table.h"
  15 #include "log.h"
  16
  17 #include "ospfd/ospfd.h"
  18 #include "ospfd/ospf_interface.h"
  19 #include "ospfd/ospf_ism.h"
  20 #include "ospfd/ospf_asbr.h"
  21 #include "ospfd/ospf_lsa.h"
  22 #include "ospfd/ospf_lsdb.h"
  23 #include "ospfd/ospf_neighbor.h"
  24 #include "ospfd/ospf_nsm.h"
  25 #include "ospfd/ospf_network.h"
  26 #include "ospfd/ospf_dump.h"
  27 #include "ospfd/ospf_packet.h"
  28 #include "ospfd/ospf_flood.h"
  29 #include "ospfd/ospf_abr.h"
  30
  31 DEFINE_HOOK(ospf_ism_change,
  32             (struct ospf_interface * oi, int state, int oldstate),
  33             (oi, state, oldstate));
  34
  35 /* elect DR and BDR. Refer to RFC2319 section 9.4 */
  36 static struct ospf_neighbor *ospf_dr_election_sub(struct list *routers)
  37 {
  38         struct listnode *node;
  39         struct ospf_neighbor *nbr, *max = NULL;
  40
  41         /* Choose highest router priority.
  42            In case of tie, choose highest Router ID. */
  43         for (ALL_LIST_ELEMENTS_RO(routers, node, nbr)) {
  44                 if (max == NULL)
  45                         max = nbr;
  46                 else {
  47                         if (max->priority < nbr->priority)
  48                                 max = nbr;
  49                         else if (max->priority == nbr->priority)
  50                                 if (IPV4_ADDR_CMP(&max->router_id,
  51                                                   &nbr->router_id)
  52                                     < 0)
  53                                         max = nbr;
  54                 }
  55         }
  56
  57         return max;
  58 }
  59
  60 static struct ospf_neighbor *ospf_elect_dr(struct ospf_interface *oi,
  61                                            struct list *el_list)
  62 {
  63         struct list *dr_list;
  64         struct listnode *node;
  65         struct ospf_neighbor *nbr, *dr = NULL, *bdr = NULL;
  66
  67         dr_list = list_new();
  68
  69         /* Add neighbors to the list. */
  70         for (ALL_LIST_ELEMENTS_RO(el_list, node, nbr)) {
  71                 /* neighbor declared to be DR. */
  72                 if (NBR_IS_DR(nbr))
  73                         listnode_add(dr_list, nbr);
  74
  75                 /* Preserve neighbor BDR. */
  76                 if (IPV4_ADDR_SAME(&BDR(oi), &nbr->address.u.prefix4))
  77                         bdr = nbr;
  78         }
  79
  80         /* Elect Designated Router. */
  81         if (listcount(dr_list) > 0)
  82                 dr = ospf_dr_election_sub(dr_list);
  83         else
  84                 dr = bdr;
  85
  86         /* Set DR to interface. */
  87         if (dr)
  88                 DR(oi) = dr->address.u.prefix4;
  89         else
  90                 DR(oi).s_addr = 0;
  91
  92         list_delete(&dr_list);
  93
  94         return dr;
  95 }
  96
  97 static struct ospf_neighbor *ospf_elect_bdr(struct ospf_interface *oi,
  98                                             struct list *el_list)
  99 {
 100         struct list *bdr_list, *no_dr_list;
 101         struct listnode *node;
 102         struct ospf_neighbor *nbr, *bdr = NULL;
 103
 104         bdr_list = list_new();
 105         no_dr_list = list_new();
 106
 107         /* Add neighbors to the list. */
 108         for (ALL_LIST_ELEMENTS_RO(el_list, node, nbr)) {
 109                 /* neighbor declared to be DR. */
 110                 if (NBR_IS_DR(nbr))
 111                         continue;
 112
 113                 /* neighbor declared to be BDR. */
 114                 if (NBR_IS_BDR(nbr))
 115                         listnode_add(bdr_list, nbr);
 116
 117                 listnode_add(no_dr_list, nbr);
 118         }
 119
 120         /* Elect Backup Designated Router. */
 121         if (listcount(bdr_list) > 0)
 122                 bdr = ospf_dr_election_sub(bdr_list);
 123         else
 124                 bdr = ospf_dr_election_sub(no_dr_list);
 125
 126         /* Set BDR to interface. */
 127         if (bdr)
 128                 BDR(oi) = bdr->address.u.prefix4;
 129         else
 130                 BDR(oi).s_addr = 0;
 131
 132         list_delete(&bdr_list);
 133         list_delete(&no_dr_list);
 134
 135         return bdr;
 136 }
 137
 138 static int ospf_ism_state(struct ospf_interface *oi)
 139 {
 140         if (IPV4_ADDR_SAME(&DR(oi), &oi->address->u.prefix4))
 141                 return ISM_DR;
 142         else if (IPV4_ADDR_SAME(&BDR(oi), &oi->address->u.prefix4))
 143                 return ISM_Backup;
 144         else
 145                 return ISM_DROther;
 146 }
 147
 148 static void ospf_dr_eligible_routers(struct route_table *nbrs,
 149                                      struct list *el_list)
 150 {
 151         struct route_node *rn;
 152         struct ospf_neighbor *nbr;
 153
 154         for (rn = route_top(nbrs); rn; rn = route_next(rn))
 155                 if ((nbr = rn->info) != NULL)
 156                         /* Ignore 0.0.0.0 node*/
 157                         if (nbr->router_id.s_addr != INADDR_ANY)
 158                                 /* Is neighbor eligible? */
 159                                 if (nbr->priority > 0)
 160                                         /* Is neighbor upper 2-Way? */
 161                                         if (nbr->state >= NSM_TwoWay)
 162                                                 listnode_add(el_list, nbr);
 163 }
 164
 165 /* Generate AdjOK? NSM event. */
 166 static void ospf_dr_change(struct ospf *ospf, struct route_table *nbrs)
 167 {
 168         struct route_node *rn;
 169         struct ospf_neighbor *nbr;
 170
 171         for (rn = route_top(nbrs); rn; rn = route_next(rn)) {
 172                 nbr = rn->info;
 173
 174                 if (!nbr)
 175                         continue;
 176
 177                 /*
 178                  * Ignore 0.0.0.0 node
 179                  * Is neighbor 2-Way?
 180                  * Ignore myself
 181                  */
 182                 if (nbr->router_id.s_addr != INADDR_ANY
 183                     && nbr->state >= NSM_TwoWay
 184                     && !IPV4_ADDR_SAME(&nbr->router_id, &ospf->router_id))
 185                         OSPF_NSM_EVENT_SCHEDULE(nbr, NSM_AdjOK);
 186         }
 187 }
 188
 189 int ospf_dr_election(struct ospf_interface *oi)
 190 {
 191         struct in_addr old_dr, old_bdr;
 192         int old_state, new_state;
 193         struct list *el_list;
 194
 195         /* backup current values. */
 196         old_dr = DR(oi);
 197         old_bdr = BDR(oi);
 198         old_state = oi->state;
 199
 200         el_list = list_new();
 201
 202         /* List eligible routers. */
 203         ospf_dr_eligible_routers(oi->nbrs, el_list);
 204
 205         /* First election of DR and BDR. */
 206         ospf_elect_bdr(oi, el_list);
 207         ospf_elect_dr(oi, el_list);
 208
 209         new_state = ospf_ism_state(oi);
 210
 211         if (IS_DEBUG_OSPF(ism, ISM_STATUS)) {
 212                 zlog_debug("DR-Election[1st]: Backup %pI4", &BDR(oi));
 213                 zlog_debug("DR-Election[1st]: DR     %pI4", &DR(oi));
 214         }
 215
 216         if (new_state != old_state
 217             && !(new_state == ISM_DROther && old_state < ISM_DROther)) {
 218                 ospf_elect_bdr(oi, el_list);
 219                 ospf_elect_dr(oi, el_list);
 220
 221                 new_state = ospf_ism_state(oi);
 222
 223                 if (IS_DEBUG_OSPF(ism, ISM_STATUS)) {
 224                         zlog_debug("DR-Election[2nd]: Backup %pI4", &BDR(oi));
 225                         zlog_debug("DR-Election[2nd]: DR     %pI4", &DR(oi));
 226                 }
 227         }
 228
 229         list_delete(&el_list);
 230
 231         /* if DR or BDR changes, cause AdjOK? neighbor event. */
 232         if (!IPV4_ADDR_SAME(&old_dr, &DR(oi))
 233             || !IPV4_ADDR_SAME(&old_bdr, &BDR(oi)))
 234                 ospf_dr_change(oi->ospf, oi->nbrs);
 235
 236         return new_state;
 237 }
 238
 239
 240 void ospf_hello_timer(struct thread *thread)
 241 {
 242         struct ospf_interface *oi;
 243
 244         oi = THREAD_ARG(thread);
 245         oi->t_hello = NULL;
 246
 247         if (IS_DEBUG_OSPF(ism, ISM_TIMERS))
 248                 zlog_debug("ISM[%s]: Timer (Hello timer expire)", IF_NAME(oi));
 249
 250         /* Sending hello packet. */
 251         ospf_hello_send(oi);
 252
 253         /* Hello timer set. */
 254         OSPF_HELLO_TIMER_ON(oi);
 255 }
 256
 257 static void ospf_wait_timer(struct thread *thread)
 258 {
 259         struct ospf_interface *oi;
 260
 261         oi = THREAD_ARG(thread);
 262         oi->t_wait = NULL;
 263
 264         if (IS_DEBUG_OSPF(ism, ISM_TIMERS))
 265                 zlog_debug("ISM[%s]: Timer (Wait timer expire)", IF_NAME(oi));
 266
 267         OSPF_ISM_EVENT_SCHEDULE(oi, ISM_WaitTimer);
 268 }
 269
 270 /* Hook function called after ospf ISM event is occurred. And vty's
 271    network command invoke this function after making interface
 272    structure. */
 273 static void ism_timer_set(struct ospf_interface *oi)
 274 {
 275         switch (oi->state) {
 276         case ISM_Down:
 277                 /* First entry point of ospf interface state machine. In this
 278                    state
 279                    interface parameters must be set to initial values, and
 280                    timers are
 281                    reset also. */
 282                 THREAD_OFF(oi->t_hello);
 283                 THREAD_OFF(oi->t_wait);
 284                 THREAD_OFF(oi->t_ls_ack);
 285                 break;
 286         case ISM_Loopback:
 287                 /* In this state, the interface may be looped back and will be
 288                    unavailable for regular data traffic. */
 289                 THREAD_OFF(oi->t_hello);
 290                 THREAD_OFF(oi->t_wait);
 291                 THREAD_OFF(oi->t_ls_ack);
 292                 break;
 293         case ISM_Waiting:
 294                 /* The router is trying to determine the identity of DRouter and
 295                    BDRouter. The router begin to receive and send Hello Packets.
 296                    */
 297                 /* send first hello immediately */
 298                 OSPF_ISM_TIMER_MSEC_ON(oi->t_hello, ospf_hello_timer, 1);
 299                 OSPF_ISM_TIMER_ON(oi->t_wait, ospf_wait_timer,
 300                                   OSPF_IF_PARAM(oi, v_wait));
 301                 THREAD_OFF(oi->t_ls_ack);
 302                 break;
 303         case ISM_PointToPoint:
 304                 /* The interface connects to a physical Point-to-point network
 305                    or
 306                    virtual link. The router attempts to form an adjacency with
 307                    neighboring router. Hello packets are also sent. */
 308                 /* send first hello immediately */
 309                 OSPF_ISM_TIMER_MSEC_ON(oi->t_hello, ospf_hello_timer, 1);
 310                 THREAD_OFF(oi->t_wait);
 311                 OSPF_ISM_TIMER_ON(oi->t_ls_ack, ospf_ls_ack_timer,
 312                                   oi->v_ls_ack);
 313                 break;
 314         case ISM_DROther:
 315                 /* The network type of the interface is broadcast or NBMA
 316                    network,
 317                    and the router itself is neither Designated Router nor
 318                    Backup Designated Router. */
 319                 OSPF_HELLO_TIMER_ON(oi);
 320                 THREAD_OFF(oi->t_wait);
 321                 OSPF_ISM_TIMER_ON(oi->t_ls_ack, ospf_ls_ack_timer,
 322                                   oi->v_ls_ack);
 323                 break;
 324         case ISM_Backup:
 325                 /* The network type of the interface is broadcast os NBMA
 326                    network,
 327                    and the router is Backup Designated Router. */
 328                 OSPF_HELLO_TIMER_ON(oi);
 329                 THREAD_OFF(oi->t_wait);
 330                 OSPF_ISM_TIMER_ON(oi->t_ls_ack, ospf_ls_ack_timer,
 331                                   oi->v_ls_ack);
 332                 break;
 333         case ISM_DR:
 334                 /* The network type of the interface is broadcast or NBMA
 335                    network,
 336                    and the router is Designated Router. */
 337                 OSPF_HELLO_TIMER_ON(oi);
 338                 THREAD_OFF(oi->t_wait);
 339                 OSPF_ISM_TIMER_ON(oi->t_ls_ack, ospf_ls_ack_timer,
 340                                   oi->v_ls_ack);
 341                 break;
 342         }
 343 }
 344
 345 static int ism_interface_up(struct ospf_interface *oi)
 346 {
 347         int next_state = 0;
 348
 349         /* if network type is point-to-point, Point-to-MultiPoint or virtual
 350            link,
 351            the state transitions to Point-to-Point. */
 352         if (oi->type == OSPF_IFTYPE_POINTOPOINT
 353             || oi->type == OSPF_IFTYPE_POINTOMULTIPOINT
 354             || oi->type == OSPF_IFTYPE_VIRTUALLINK)
 355                 next_state = ISM_PointToPoint;
 356         /* Else if the router is not eligible to DR, the state transitions to
 357            DROther. */
 358         else if (PRIORITY(oi) == 0) /* router is eligible? */
 359                 next_state = ISM_DROther;
 360         else
 361                 /* Otherwise, the state transitions to Waiting. */
 362                 next_state = ISM_Waiting;
 363
 364         if (oi->type == OSPF_IFTYPE_NBMA)
 365                 ospf_nbr_nbma_if_update(oi->ospf, oi);
 366
 367         /*  ospf_ism_event (t); */
 368         return next_state;
 369 }
 370
 371 static int ism_loop_ind(struct ospf_interface *oi)
 372 {
 373         /* call ism_interface_down. */
 374         /* ret = ism_interface_down (oi); */
 375
 376         return 0;
 377 }
 378
 379 /* Interface down event handler. */
 380 static int ism_interface_down(struct ospf_interface *oi)
 381 {
 382         ospf_if_cleanup(oi);
 383         return 0;
 384 }
 385
 386
 387 static int ism_backup_seen(struct ospf_interface *oi)
 388 {
 389         return ospf_dr_election(oi);
 390 }
 391
 392 static int ism_wait_timer(struct ospf_interface *oi)
 393 {
 394         return ospf_dr_election(oi);
 395 }
 396
 397 static int ism_neighbor_change(struct ospf_interface *oi)
 398 {
 399         return ospf_dr_election(oi);
 400 }
 401
 402 static int ism_ignore(struct ospf_interface *oi)
 403 {
 404         if (IS_DEBUG_OSPF(ism, ISM_EVENTS))
 405                 zlog_debug("ISM[%s]: ism_ignore called", IF_NAME(oi));
 406
 407         return 0;
 408 }
 409
 410 /* Interface State Machine */
 411 const struct {
 412         int (*func)(struct ospf_interface *);
 413         int next_state;
 414 } ISM[OSPF_ISM_STATE_MAX][OSPF_ISM_EVENT_MAX] = {
 415         {
 416                 /* DependUpon: dummy state. */
 417                 {ism_ignore, ISM_DependUpon}, /* NoEvent        */
 418                 {ism_ignore, ISM_DependUpon}, /* InterfaceUp    */
 419                 {ism_ignore, ISM_DependUpon}, /* WaitTimer      */
 420                 {ism_ignore, ISM_DependUpon}, /* BackupSeen     */
 421                 {ism_ignore, ISM_DependUpon}, /* NeighborChange */
 422                 {ism_ignore, ISM_DependUpon}, /* LoopInd        */
 423                 {ism_ignore, ISM_DependUpon}, /* UnloopInd      */
 424                 {ism_ignore, ISM_DependUpon}, /* InterfaceDown  */
 425         },
 426         {
 427                 /* Down:*/
 428                 {ism_ignore, ISM_DependUpon},       /* NoEvent        */
 429                 {ism_interface_up, ISM_DependUpon}, /* InterfaceUp    */
 430                 {ism_ignore, ISM_Down},             /* WaitTimer      */
 431                 {ism_ignore, ISM_Down},             /* BackupSeen     */
 432                 {ism_ignore, ISM_Down},             /* NeighborChange */
 433                 {ism_loop_ind, ISM_Loopback},       /* LoopInd        */
 434                 {ism_ignore, ISM_Down},             /* UnloopInd      */
 435                 {ism_interface_down, ISM_Down},     /* InterfaceDown  */
 436         },
 437         {
 438                 /* Loopback: */
 439                 {ism_ignore, ISM_DependUpon},   /* NoEvent        */
 440                 {ism_ignore, ISM_Loopback},     /* InterfaceUp    */
 441                 {ism_ignore, ISM_Loopback},     /* WaitTimer      */
 442                 {ism_ignore, ISM_Loopback},     /* BackupSeen     */
 443                 {ism_ignore, ISM_Loopback},     /* NeighborChange */
 444                 {ism_ignore, ISM_Loopback},     /* LoopInd        */
 445                 {ism_ignore, ISM_Down},         /* UnloopInd      */
 446                 {ism_interface_down, ISM_Down}, /* InterfaceDown  */
 447         },
 448         {
 449                 /* Waiting: */
 450                 {ism_ignore, ISM_DependUpon},      /* NoEvent        */
 451                 {ism_ignore, ISM_Waiting},       /* InterfaceUp    */
 452                 {ism_wait_timer, ISM_DependUpon},  /* WaitTimer      */
 453                 {ism_backup_seen, ISM_DependUpon}, /* BackupSeen     */
 454                 {ism_ignore, ISM_Waiting},       /* NeighborChange */
 455                 {ism_loop_ind, ISM_Loopback},      /* LoopInd        */
 456                 {ism_ignore, ISM_Waiting},       /* UnloopInd      */
 457                 {ism_interface_down, ISM_Down},    /* InterfaceDown  */
 458         },
 459         {
 460                 /* Point-to-Point: */
 461                 {ism_ignore, ISM_DependUpon},   /* NoEvent        */
 462                 {ism_ignore, ISM_PointToPoint}, /* InterfaceUp    */
 463                 {ism_ignore, ISM_PointToPoint}, /* WaitTimer      */
 464                 {ism_ignore, ISM_PointToPoint}, /* BackupSeen     */
 465                 {ism_ignore, ISM_PointToPoint}, /* NeighborChange */
 466                 {ism_loop_ind, ISM_Loopback},   /* LoopInd        */
 467                 {ism_ignore, ISM_PointToPoint}, /* UnloopInd      */
 468                 {ism_interface_down, ISM_Down}, /* InterfaceDown  */
 469         },
 470         {
 471                 /* DROther: */
 472                 {ism_ignore, ISM_DependUpon},     /* NoEvent        */
 473                 {ism_ignore, ISM_DROther},           /* InterfaceUp    */
 474                 {ism_ignore, ISM_DROther},           /* WaitTimer      */
 475                 {ism_ignore, ISM_DROther},           /* BackupSeen     */
 476                 {ism_neighbor_change, ISM_DependUpon}, /* NeighborChange */
 477                 {ism_loop_ind, ISM_Loopback},     /* LoopInd        */
 478                 {ism_ignore, ISM_DROther},           /* UnloopInd      */
 479                 {ism_interface_down, ISM_Down}, /* InterfaceDown  */
 480         },
 481         {
 482                 /* Backup: */
 483                 {ism_ignore, ISM_DependUpon},     /* NoEvent        */
 484                 {ism_ignore, ISM_Backup},             /* InterfaceUp    */
 485                 {ism_ignore, ISM_Backup},             /* WaitTimer      */
 486                 {ism_ignore, ISM_Backup},             /* BackupSeen     */
 487                 {ism_neighbor_change, ISM_DependUpon}, /* NeighborChange */
 488                 {ism_loop_ind, ISM_Loopback},     /* LoopInd        */
 489                 {ism_ignore, ISM_Backup},             /* UnloopInd      */
 490                 {ism_interface_down, ISM_Down}, /* InterfaceDown  */
 491         },
 492         {
 493                 /* DR: */
 494                 {ism_ignore, ISM_DependUpon},     /* NoEvent        */
 495                 {ism_ignore, ISM_DR},                  /* InterfaceUp    */
 496                 {ism_ignore, ISM_DR},                  /* WaitTimer      */
 497                 {ism_ignore, ISM_DR},                  /* BackupSeen     */
 498                 {ism_neighbor_change, ISM_DependUpon}, /* NeighborChange */
 499                 {ism_loop_ind, ISM_Loopback},     /* LoopInd        */
 500                 {ism_ignore, ISM_DR},                  /* UnloopInd      */
 501                 {ism_interface_down, ISM_Down}, /* InterfaceDown  */
 502         },
 503 };
 504
 505 static const char *const ospf_ism_event_str[] = {
 506         "NoEvent",      "InterfaceUp", "WaitTimer", "BackupSeen",
 507         "NeighborChange", "LoopInd",     "UnLoopInd", "InterfaceDown",
 508 };
 509
 510 static void ism_change_state(struct ospf_interface *oi, int state)
 511 {
 512         int old_state;
 513         struct ospf_lsa *lsa;
 514
 515         /* Logging change of state. */
 516         if (IS_DEBUG_OSPF(ism, ISM_STATUS))
 517                 zlog_debug("ISM[%s]: State change %s -> %s", IF_NAME(oi),
 518                            lookup_msg(ospf_ism_state_msg, oi->state, NULL),
 519                            lookup_msg(ospf_ism_state_msg, state, NULL));
 520
 521         old_state = oi->state;
 522         oi->state = state;
 523         oi->state_change++;
 524
 525         hook_call(ospf_ism_change, oi, state, old_state);
 526
 527         /* Set multicast memberships appropriately for new state. */
 528         ospf_if_set_multicast(oi);
 529
 530         if (old_state == ISM_Down || state == ISM_Down)
 531                 ospf_check_abr_status(oi->ospf);
 532
 533         /* Originate router-LSA. */
 534         if (state == ISM_Down) {
 535                 if (oi->area->act_ints > 0)
 536                         oi->area->act_ints--;
 537         } else if (old_state == ISM_Down)
 538                 oi->area->act_ints++;
 539
 540         /* schedule router-LSA originate. */
 541         ospf_router_lsa_update_area(oi->area);
 542
 543         /* Originate network-LSA. */
 544         if (old_state != ISM_DR && state == ISM_DR)
 545                 ospf_network_lsa_update(oi);
 546         else if (old_state == ISM_DR && state != ISM_DR) {
 547                 /* Free self originated network LSA. */
 548                 lsa = oi->network_lsa_self;
 549                 if (lsa)
 550                         ospf_lsa_flush_area(lsa, oi->area);
 551
 552                 ospf_lsa_unlock(&oi->network_lsa_self);
 553                 oi->network_lsa_self = NULL;
 554         }
 555
 556         ospf_opaque_ism_change(oi, old_state);
 557
 558         /* Check area border status.  */
 559         ospf_check_abr_status(oi->ospf);
 560 }
 561
 562 /* Execute ISM event process. */
 563 void ospf_ism_event(struct thread *thread)
 564 {
 565         int event;
 566         int next_state;
 567         struct ospf_interface *oi;
 568
 569         oi = THREAD_ARG(thread);
 570         event = THREAD_VAL(thread);
 571
 572         /* Call function. */
 573         next_state = (*(ISM[oi->state][event].func))(oi);
 574
 575         if (!next_state)
 576                 next_state = ISM[oi->state][event].next_state;
 577
 578         if (IS_DEBUG_OSPF(ism, ISM_EVENTS))
 579                 zlog_debug("ISM[%s]: %s (%s)", IF_NAME(oi),
 580                            lookup_msg(ospf_ism_state_msg, oi->state, NULL),
 581                            ospf_ism_event_str[event]);
 582
 583         /* If state is changed. */
 584         if (next_state != oi->state)
 585                 ism_change_state(oi, next_state);
 586
 587         /* Make sure timer is set. */
 588         ism_timer_set(oi);
 589 }