From endo@suri.co.jp Fri Jan 17 23:36:30 2003

Date: Fri, 20 Dec 2002 17:58:43 +0900
From: Masahiko Endo <endo@suri.co.jp>
Reply-To: zebra@zebra.org
To: zebra@zebra.org
Cc: kunihiro@zebra.org
Subject: [zebra 16824] [PATCH] nsm_kill_neighbor

    [ The following text is in the "ISO-2022-JP" character set. ]
    [ Your display is set for the "ISO-8859-1" character set.  ]
    [ Some characters may be displayed incorrectly. ]

Hi Ishiguro-san,

Here is my problem analysis against the case that the ospfd crashes
when an interface is brought down.

When the ospfd receives a ZEBRA message "ZEBRA_INTERFACE_DOWN" from
zebra daemon, the ospfd performs bunch of ospf-interface cleanup for
the notified zebra-interface.
There are cases that neighbor instance "nbr", which will be removed
afterward, may scheduled in the NSM thread event queue. And when the
NSM event thread is fired, dereference for this already freed "nbr"
pointer causes SIGSEGV.
Please take a look at following timeline of processing sequences.

1 files changed, 658 insertions, 0 deletions

diff --git a/ospfd/ospf_ism.c b/ospfd/ospf_ism.c
new file mode 100644
index 00000000..b47487f0
--- /dev/null
+++ b/ospfd/ospf_ism.c
@@ -0,0 +1,658 @@
+/*
+ * OSPF version 2  Interface State Machine
+ *   From RFC2328 [OSPF Version 2] 
+ * Copyright (C) 1999, 2000 Toshiaki Takada
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Zebra; see the file COPYING.  If not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <zebra.h>
+
+#include "thread.h"
+#include "linklist.h"
+#include "prefix.h"
+#include "if.h"
+#include "table.h"
+#include "log.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_network.h"
+#include "ospfd/ospf_dump.h"
+#include "ospfd/ospf_packet.h"
+#include "ospfd/ospf_flood.h"
+#include "ospfd/ospf_abr.h"
+
+/* elect DR and BDR. Refer to RFC2319 section 9.4 */
+struct ospf_neighbor *
+ospf_dr_election_sub (list routers)
+{
+  listnode node;
+  struct ospf_neighbor *nbr, *max = NULL;
+
+  /* Choose highest router priority.
+     In case of tie, choose highest Router ID. */
+  for (node = listhead (routers); node; nextnode (node))
+    {
+      nbr = getdata (node);
+
+      if (max == NULL)
+	max = nbr;
+      else
+	{
+	  if (max->priority < nbr->priority)
+	    max = nbr;
+	  else if (max->priority == nbr->priority)
+	    if (IPV4_ADDR_CMP (&max->router_id, &nbr->router_id) < 0)
+	      max = nbr;
+	}
+    }
+
+  return max;
+}
+
+struct ospf_neighbor *
+ospf_elect_dr (struct ospf_interface *oi, list el_list)
+{
+  list dr_list;
+  listnode node;
+  struct ospf_neighbor *nbr, *dr = NULL, *bdr = NULL;
+
+  dr_list = list_new ();
+
+  /* Add neighbors to the list. */
+  for (node = listhead (el_list); node; nextnode (node))
+    {
+      nbr = getdata (node);
+
+      /* neighbor declared to be DR. */
+      if (NBR_IS_DR (nbr))
+	listnode_add (dr_list, nbr);
+
+      /* Preserve neighbor BDR. */
+      if (IPV4_ADDR_SAME (&BDR (oi), &nbr->address.u.prefix4))
+	bdr = nbr;
+    }
+
+  /* Elect Designated Router. */
+  if (listcount (dr_list) > 0)
+    dr = ospf_dr_election_sub (dr_list);
+  else
+    dr = bdr;
+
+  /* Set DR to interface. */
+  if (dr)
+    {
+      DR (oi) = dr->address.u.prefix4;
+      dr->d_router = dr->address.u.prefix4;
+    }
+  else
+      DR (oi).s_addr = 0;
+
+  list_delete (dr_list);
+
+  return dr;
+}
+
+struct ospf_neighbor *
+ospf_elect_bdr (struct ospf_interface *oi, list el_list)
+{
+  list bdr_list, no_dr_list;
+  listnode node;
+  struct ospf_neighbor *nbr, *bdr = NULL;
+
+  bdr_list = list_new ();
+  no_dr_list = list_new ();
+
+  /* Add neighbors to the list. */
+  for (node = listhead (el_list); node; nextnode (node))
+    {
+      nbr = getdata (node);
+
+      /* neighbor declared to be DR. */
+      if (NBR_IS_DR (nbr))
+	continue;
+
+      /* neighbor declared to be BDR. */
+      if (NBR_IS_BDR (nbr))
+	listnode_add (bdr_list, nbr);
+
+      listnode_add (no_dr_list, nbr);
+    }
+
+  /* Elect Backup Designated Router. */
+  if (listcount (bdr_list) > 0)
+    bdr = ospf_dr_election_sub (bdr_list);
+  else
+    bdr = ospf_dr_election_sub (no_dr_list);
+
+  /* Set BDR to interface. */
+  if (bdr)
+    {
+      BDR (oi) = bdr->address.u.prefix4;
+      bdr->bd_router = bdr->address.u.prefix4;
+    }
+  else
+    BDR (oi).s_addr = 0;
+
+  list_delete (bdr_list);
+  list_delete (no_dr_list);
+
+  return bdr;
+}
+
+int
+ospf_ism_state (struct ospf_interface *oi)
+{
+  if (IPV4_ADDR_SAME (&DR (oi), &oi->address->u.prefix4))
+    return ISM_DR;
+  else if (IPV4_ADDR_SAME (&BDR (oi), &oi->address->u.prefix4))
+    return ISM_Backup;
+  else
+    return ISM_DROther;
+}
+
+void
+ospf_dr_eligible_routers (struct route_table *nbrs, list el_list)
+{
+  struct route_node *rn;
+  struct ospf_neighbor *nbr;
+
+  for (rn = route_top (nbrs); rn; rn = route_next (rn))
+    if ((nbr = rn->info) != NULL)
+      /* Ignore 0.0.0.0 node*/
+      if (nbr->router_id.s_addr != 0)
+	/* Is neighbor eligible? */
+	if (nbr->priority != 0)
+	  /* Is neighbor upper 2-Way? */
+	  if (nbr->state >= NSM_TwoWay)
+	    listnode_add (el_list, nbr);
+}
+
+/* Generate AdjOK? NSM event. */
+void
+ospf_dr_change (struct route_table *nbrs)
+{
+  struct route_node *rn;
+  struct ospf_neighbor *nbr;
+
+  for (rn = route_top (nbrs); rn; rn = route_next (rn))
+    if ((nbr = rn->info) != NULL)
+      /* Ignore 0.0.0.0 node*/
+      if (nbr->router_id.s_addr != 0)
+	/* Is neighbor upper 2-Way? */
+	if (nbr->state >= NSM_TwoWay)
+	  /* Ignore myself. */
+	  if (!IPV4_ADDR_SAME (&nbr->router_id, &ospf_top->router_id))
+	    OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_AdjOK);
+}
+
+int
+ospf_dr_election (struct ospf_interface *oi)
+{
+  struct in_addr old_dr, old_bdr;
+  int old_state, new_state;
+  list el_list;
+  struct ospf_neighbor *dr, *bdr;
+
+  /* backup current values. */
+  old_dr = DR (oi);
+  old_bdr = BDR (oi);
+  old_state = oi->state;
+
+  el_list = list_new ();
+
+  /* List eligible routers. */
+  ospf_dr_eligible_routers (oi->nbrs, el_list);
+
+  /* First election of DR and BDR. */
+  bdr = ospf_elect_bdr (oi, el_list);
+  dr = ospf_elect_dr (oi, el_list);
+
+  new_state = ospf_ism_state (oi);
+
+  zlog_info ("DR-Election[1st]: Backup %s", inet_ntoa (BDR (oi)));
+  zlog_info ("DR-Election[1st]: DR     %s", inet_ntoa (DR (oi)));
+
+  if (new_state != old_state &&
+      !(new_state == ISM_DROther && old_state < ISM_DROther))
+    {
+      ospf_elect_bdr (oi, el_list);
+      ospf_elect_dr (oi, el_list); 
+
+      new_state = ospf_ism_state (oi);
+
+      zlog_info ("DR-Election[2nd]: Backup %s", inet_ntoa (BDR (oi)));
+      zlog_info ("DR-Election[2nd]: DR     %s", inet_ntoa (DR (oi)));
+    }
+
+  list_delete (el_list);
+
+  /* if DR or BDR changes, cause AdjOK? neighbor event. */
+  if (!IPV4_ADDR_SAME (&old_dr, &DR (oi)) ||
+      !IPV4_ADDR_SAME (&old_bdr, &BDR (oi)))
+    ospf_dr_change (oi->nbrs);
+
+  if (oi->type == OSPF_IFTYPE_BROADCAST || oi->type == OSPF_IFTYPE_POINTOPOINT)
+    {
+      /* Multicast group change. */
+      if ((old_state != ISM_DR && old_state != ISM_Backup) &&
+	  (new_state == ISM_DR || new_state == ISM_Backup))
+	ospf_if_add_alldrouters (ospf_top, oi->address, oi->ifp->ifindex);
+      else if ((old_state == ISM_DR || old_state == ISM_Backup) &&
+	       (new_state != ISM_DR && new_state != ISM_Backup))
+	ospf_if_drop_alldrouters (ospf_top, oi->address, oi->ifp->ifindex);
+    }
+
+  return new_state;
+}
+
+
+int
+ospf_hello_timer (struct thread *thread)
+{
+  struct ospf_interface *oi;
+
+  oi = THREAD_ARG (thread);
+  oi->t_hello = NULL;
+
+  if (IS_DEBUG_OSPF (ism, ISM_TIMERS))
+    zlog (NULL, LOG_DEBUG, "ISM[%s]: Timer (Hello timer expire)",
+	  IF_NAME (oi));
+
+  /* Sending hello packet. */
+  ospf_hello_send (oi);
+
+  /* Hello timer set. */
+  OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
+		     OSPF_IF_PARAM (oi, v_hello));
+
+  return 0;
+}
+
+int
+ospf_wait_timer (struct thread *thread)
+{
+  struct ospf_interface *oi;
+
+  oi = THREAD_ARG (thread);
+  oi->t_wait = NULL;
+
+  if (IS_DEBUG_OSPF (ism, ISM_TIMERS))
+    zlog (NULL, LOG_DEBUG, "ISM[%s]: Timer (Wait timer expire)",
+	  IF_NAME (oi));
+
+  OSPF_ISM_EVENT_SCHEDULE (oi, ISM_WaitTimer);
+
+  return 0;
+}
+
+/* Hook function called after ospf ISM event is occured. And vty's
+   network command invoke this function after making interface
+   structure. */
+void
+ism_timer_set (struct ospf_interface *oi)
+{
+  switch (oi->state)
+    {
+    case ISM_Down:
+      /* First entry point of ospf interface state machine. In this state
+	 interface parameters must be set to initial values, and timers are
+	 reset also. */
+      OSPF_ISM_TIMER_OFF (oi->t_hello);
+      OSPF_ISM_TIMER_OFF (oi->t_wait);
+      OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
+      break;
+    case ISM_Loopback:
+      /* In this state, the interface may be looped back and will be
+	 unavailable for regular data traffic. */
+      OSPF_ISM_TIMER_OFF (oi->t_hello);
+      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_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();
+
+  /* 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 ();
+}
+
+/* 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;
+}
+