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-rw-r--r--ospfd/ospf_ism.c595
1 files changed, 595 insertions, 0 deletions
diff --git a/ospfd/ospf_ism.c b/ospfd/ospf_ism.c
new file mode 100644
index 0000000..2516fa7
--- /dev/null
+++ b/ospfd/ospf_ism.c
@@ -0,0 +1,595 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * OSPF version 2 Interface State Machine
+ * From RFC2328 [OSPF Version 2]
+ * Copyright (C) 1999, 2000 Toshiaki Takada
+ */
+
+#include <zebra.h>
+
+#include "frrevent.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"
+
+DEFINE_HOOK(ospf_ism_change,
+ (struct ospf_interface * oi, int state, int oldstate),
+ (oi, state, oldstate));
+
+/* 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 != INADDR_ANY)
+ /* 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)) {
+ nbr = rn->info;
+
+ if (!nbr)
+ continue;
+
+ /*
+ * Ignore 0.0.0.0 node
+ * Is neighbor 2-Way?
+ * Ignore myself
+ */
+ if (nbr->router_id.s_addr != INADDR_ANY
+ && nbr->state >= NSM_TwoWay
+ && !IPV4_ADDR_SAME(&nbr->router_id, &ospf->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;
+ 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);
+
+ if (IS_DEBUG_OSPF(ism, ISM_STATUS)) {
+ zlog_debug("DR-Election[1st]: Backup %pI4", &BDR(oi));
+ zlog_debug("DR-Election[1st]: DR %pI4", &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);
+
+ if (IS_DEBUG_OSPF(ism, ISM_STATUS)) {
+ zlog_debug("DR-Election[2nd]: Backup %pI4", &BDR(oi));
+ zlog_debug("DR-Election[2nd]: DR %pI4", &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;
+}
+
+
+void ospf_hello_timer(struct event *thread)
+{
+ struct ospf_interface *oi;
+
+ oi = EVENT_ARG(thread);
+ oi->t_hello = NULL;
+
+ /* Check if the GR hello-delay is active. */
+ if (oi->gr.hello_delay.t_grace_send)
+ return;
+
+ if (IS_DEBUG_OSPF(ism, ISM_TIMERS))
+ zlog_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);
+}
+
+static void ospf_wait_timer(struct event *thread)
+{
+ struct ospf_interface *oi;
+
+ oi = EVENT_ARG(thread);
+ oi->t_wait = NULL;
+
+ if (IS_DEBUG_OSPF(ism, ISM_TIMERS))
+ zlog_debug("ISM[%s]: Timer (Wait timer expire)", IF_NAME(oi));
+
+ OSPF_ISM_EVENT_SCHEDULE(oi, ISM_WaitTimer);
+}
+
+/* Hook function called after ospf ISM event is occurred. 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. */
+ EVENT_OFF(oi->t_hello);
+ EVENT_OFF(oi->t_wait);
+ EVENT_OFF(oi->t_ls_ack);
+ EVENT_OFF(oi->gr.hello_delay.t_grace_send);
+ break;
+ case ISM_Loopback:
+ /* In this state, the interface may be looped back and will be
+ unavailable for regular data traffic. */
+ EVENT_OFF(oi->t_hello);
+ EVENT_OFF(oi->t_wait);
+ EVENT_OFF(oi->t_ls_ack);
+ EVENT_OFF(oi->gr.hello_delay.t_grace_send);
+ 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));
+ EVENT_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);
+ EVENT_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);
+ EVENT_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);
+ EVENT_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);
+ EVENT_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)
+{
+ /* call ism_interface_down. */
+ /* ret = ism_interface_down (oi); */
+
+ return 0;
+}
+
+/* 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_debug("ISM[%s]: ism_ignore called", IF_NAME(oi));
+
+ return 0;
+}
+
+/* Interface State Machine */
+const 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 *const 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_debug("ISM[%s]: State change %s -> %s", IF_NAME(oi),
+ lookup_msg(ospf_ism_state_msg, oi->state, NULL),
+ lookup_msg(ospf_ism_state_msg, state, NULL));
+
+ old_state = oi->state;
+ oi->state = state;
+ oi->state_change++;
+
+ hook_call(ospf_ism_change, oi, state, old_state);
+
+ /* 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;
+ }
+
+ ospf_opaque_ism_change(oi, old_state);
+
+ /* Check area border status. */
+ ospf_check_abr_status(oi->ospf);
+}
+
+/* Execute ISM event process. */
+void ospf_ism_event(struct event *thread)
+{
+ int event;
+ int next_state;
+ struct ospf_interface *oi;
+
+ oi = EVENT_ARG(thread);
+ event = EVENT_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_debug("ISM[%s]: %s (%s)", IF_NAME(oi),
+ lookup_msg(ospf_ism_state_msg, oi->state, NULL),
+ 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);
+}
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