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/*
* 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"
#include "ospfd/ospf_snmp.h"
/* elect DR and BDR. Refer to RFC2319 section 9.4 */
static struct ospf_neighbor *
ospf_dr_election_sub (struct list *routers)
{
struct listnode *node;
struct ospf_neighbor *nbr, *max = NULL;
/* Choose highest router priority.
In case of tie, choose highest Router ID. */
for (ALL_LIST_ELEMENTS_RO (routers, node, nbr))
{
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;
}
static struct ospf_neighbor *
ospf_elect_dr (struct ospf_interface *oi, struct list *el_list)
{
struct list *dr_list;
struct listnode *node;
struct ospf_neighbor *nbr, *dr = NULL, *bdr = NULL;
dr_list = list_new ();
/* Add neighbors to the list. */
for (ALL_LIST_ELEMENTS_RO (el_list, node, nbr))
{
/* 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;
else
DR (oi).s_addr = 0;
list_delete (dr_list);
return dr;
}
static struct ospf_neighbor *
ospf_elect_bdr (struct ospf_interface *oi, struct list *el_list)
{
struct list *bdr_list, *no_dr_list;
struct listnode *node;
struct ospf_neighbor *nbr, *bdr = NULL;
bdr_list = list_new ();
no_dr_list = list_new ();
/* Add neighbors to the list. */
for (ALL_LIST_ELEMENTS_RO (el_list, node, nbr))
{
/* 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;
else
BDR (oi).s_addr = 0;
list_delete (bdr_list);
list_delete (no_dr_list);
return bdr;
}
static 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;
}
static void
ospf_dr_eligible_routers (struct route_table *nbrs, struct 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. */
static void
ospf_dr_change (struct ospf *ospf, 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->router_id))
OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_AdjOK);
}
static int
ospf_dr_election (struct ospf_interface *oi)
{
struct in_addr old_dr, old_bdr;
int old_state, new_state;
struct list *el_list;
/* 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. */
ospf_elect_bdr (oi, el_list);
ospf_elect_dr (oi, el_list);
new_state = ospf_ism_state (oi);
zlog_debug ("DR-Election[1st]: Backup %s", inet_ntoa (BDR (oi)));
zlog_debug ("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_debug ("DR-Election[2nd]: Backup %s", inet_ntoa (BDR (oi)));
zlog_debug ("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->ospf, oi->nbrs);
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_HELLO_TIMER_ON (oi);
return 0;
}
static 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. */
static 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_MSEC_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_MSEC_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_HELLO_TIMER_ON (oi);
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_HELLO_TIMER_ON (oi);
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_HELLO_TIMER_ON (oi);
OSPF_ISM_TIMER_OFF (oi->t_wait);
OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
break;
}
}
static 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;
}
static 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. */
static int
ism_interface_down (struct ospf_interface *oi)
{
ospf_if_cleanup (oi);
return 0;
}
static int
ism_backup_seen (struct ospf_interface *oi)
{
return ospf_dr_election (oi);
}
static int
ism_wait_timer (struct ospf_interface *oi)
{
return ospf_dr_election (oi);
}
static int
ism_neighbor_change (struct ospf_interface *oi)
{
return ospf_dr_election (oi);
}
static int
ism_ignore (struct ospf_interface *oi)
{
if (IS_DEBUG_OSPF (ism, ISM_EVENTS))
zlog (NULL, LOG_DEBUG, "ISM[%s]: ism_ignore called", IF_NAME (oi));
return 0;
}
/* Interface State Machine */
struct {
int (*func) (struct ospf_interface *);
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 const char *ospf_ism_event_str[] =
{
"NoEvent",
"InterfaceUp",
"WaitTimer",
"BackupSeen",
"NeighborChange",
"LoopInd",
"UnLoopInd",
"InterfaceDown",
};
static 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_DEBUG, "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++;
#ifdef HAVE_SNMP
/* Terminal state or regression */
if ((state == ISM_DR) || (state == ISM_Backup) || (state == ISM_DROther) ||
(state == ISM_PointToPoint) || (state < old_state))
{
/* ospfVirtIfStateChange */
if (oi->type == OSPF_IFTYPE_VIRTUALLINK)
ospfTrapVirtIfStateChange (oi);
/* ospfIfStateChange */
else
ospfTrapIfStateChange (oi);
}
#endif
/* Set multicast memberships appropriately for new state. */
ospf_if_set_multicast(oi);
if (old_state == ISM_Down || state == ISM_Down)
ospf_check_abr_status (oi->ospf);
/* Originate router-LSA. */
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_update_area (oi->area);
/* Originate network-LSA. */
if (old_state != ISM_DR && state == ISM_DR)
ospf_network_lsa_update (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_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_DEBUG, "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;
}
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