ospfd,ospf6d: Add missing newline for `graceful-restart prepare` CLI

[mirror_frr.git] / ospfd / ospf_gr.c

/*
 * This is an implementation of RFC 3623 Graceful OSPF Restart.
 *
 * Copyright 2021 NetDEF (c), All rights reserved.
 * Copyright 2020 6WIND (c), All rights reserved.
 *
 * This program 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 of the License, or (at your option)
 * any later version.
 *
 * This program 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 this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <zebra.h>

#include "memory.h"
#include "command.h"
#include "table.h"
#include "vty.h"
#include "log.h"
#include "printfrr.h"

#include "ospfd/ospfd.h"
#include "ospfd/ospf_abr.h"
#include "ospfd/ospf_flood.h"
#include "ospfd/ospf_ism.h"
#include "ospfd/ospf_interface.h"
#include "ospfd/ospf_asbr.h"
#include "ospfd/ospf_lsa.h"
#include "ospfd/ospf_route.h"
#include "ospfd/ospf_zebra.h"
#include "ospfd/ospf_lsdb.h"
#include "ospfd/ospf_neighbor.h"
#include "ospfd/ospf_opaque.h"
#include "ospfd/ospf_nsm.h"
#include "ospfd/ospf_gr.h"
#include "ospfd/ospf_errors.h"
#include "ospfd/ospf_dump.h"
#ifndef VTYSH_EXTRACT_PL
#include "ospfd/ospf_gr_clippy.c"
#endif

static void ospf_gr_nvm_delete(struct ospf *ospf);

/* Lookup self-originated Grace-LSA in the LSDB. */
static struct ospf_lsa *ospf_gr_lsa_lookup(struct ospf *ospf,
                                           struct ospf_area *area)
{
        struct ospf_lsa *lsa;
        struct in_addr lsa_id;
        uint32_t lsa_id_host_byte_order;

        lsa_id_host_byte_order = SET_OPAQUE_LSID(OPAQUE_TYPE_GRACE_LSA, 0);
        lsa_id.s_addr = htonl(lsa_id_host_byte_order);
        lsa = ospf_lsa_lookup(ospf, area, OSPF_OPAQUE_LINK_LSA, lsa_id,
                              ospf->router_id);

        return lsa;
}

/* Fill in fields of the Grace-LSA that is being originated. */
static void ospf_gr_lsa_body_set(struct ospf_gr_info *gr_info,
                                 struct ospf_interface *oi, struct stream *s)
{
        struct grace_tlv_graceperiod tlv_period = {};
        struct grace_tlv_restart_reason tlv_reason = {};
        struct grace_tlv_restart_addr tlv_address = {};

        /* Put grace period. */
        tlv_period.header.type = htons(GRACE_PERIOD_TYPE);
        tlv_period.header.length = htons(GRACE_PERIOD_LENGTH);
        tlv_period.interval = htonl(gr_info->grace_period);
        stream_put(s, &tlv_period, sizeof(tlv_period));

        /* Put restart reason. */
        tlv_reason.header.type = htons(RESTART_REASON_TYPE);
        tlv_reason.header.length = htons(RESTART_REASON_LENGTH);
        if (gr_info->restart_support)
                tlv_reason.reason = OSPF_GR_SW_RESTART;
        else
                tlv_reason.reason = OSPF_GR_UNKNOWN_RESTART;
        stream_put(s, &tlv_reason, sizeof(tlv_reason));

        /* Put IP address. */
        if (oi->type == OSPF_IFTYPE_BROADCAST || oi->type == OSPF_IFTYPE_NBMA
            || oi->type == OSPF_IFTYPE_POINTOMULTIPOINT) {
                tlv_address.header.type = htons(RESTARTER_IP_ADDR_TYPE);
                tlv_address.header.length = htons(RESTARTER_IP_ADDR_LEN);
                tlv_address.addr = oi->address->u.prefix4;
                stream_put(s, &tlv_address, sizeof(tlv_address));
        }
}

/* Generate Grace-LSA for a given interface. */
static struct ospf_lsa *ospf_gr_lsa_new(struct ospf_interface *oi)
{
        struct stream *s;
        struct lsa_header *lsah;
        struct ospf_lsa *new;
        uint8_t options, lsa_type;
        struct in_addr lsa_id;
        uint32_t lsa_id_host_byte_order;
        uint16_t length;

        /* Create a stream for LSA. */
        s = stream_new(OSPF_MAX_LSA_SIZE);

        lsah = (struct lsa_header *)STREAM_DATA(s);

        options = LSA_OPTIONS_GET(oi->area);
        options |= LSA_OPTIONS_NSSA_GET(oi->area);
        options |= OSPF_OPTION_O;

        lsa_type = OSPF_OPAQUE_LINK_LSA;
        lsa_id_host_byte_order = SET_OPAQUE_LSID(OPAQUE_TYPE_GRACE_LSA, 0);
        lsa_id.s_addr = htonl(lsa_id_host_byte_order);

        /* Set opaque-LSA header fields. */
        lsa_header_set(s, options, lsa_type, lsa_id, oi->ospf->router_id);

        /* Set opaque-LSA body fields. */
        ospf_gr_lsa_body_set(&oi->ospf->gr_info, oi, s);

        /* Set length. */
        length = stream_get_endp(s);
        lsah->length = htons(length);

        /* Now, create an OSPF LSA instance. */
        new = ospf_lsa_new_and_data(length);

        if (IS_DEBUG_OSPF_GR)
                zlog_debug("LSA[Type%d:%pI4]: Create an Opaque-LSA/GR instance",
                           lsa_type, &lsa_id);

        new->area = oi->area;
        new->oi = oi;
        SET_FLAG(new->flags, OSPF_LSA_SELF);
        memcpy(new->data, lsah, length);
        stream_free(s);

        return new;
}

/* Originate and install Grace-LSA for a given interface. */
static void ospf_gr_lsa_originate(struct ospf_interface *oi, bool maxage)
{
        struct ospf_lsa *lsa, *old;

        if (ospf_interface_neighbor_count(oi) == 0)
                return;

        /* Create new Grace-LSA. */
        lsa = ospf_gr_lsa_new(oi);
        if (!lsa) {
                zlog_warn("%s: ospf_gr_lsa_new() failed", __func__);
                return;
        }

        if (maxage)
                lsa->data->ls_age = htons(OSPF_LSA_MAXAGE);

        /* Find the old LSA and increase the seqno. */
        old = ospf_gr_lsa_lookup(oi->ospf, oi->area);
        if (old)
                lsa->data->ls_seqnum = lsa_seqnum_increment(old);

        /* Install this LSA into LSDB. */
        if (ospf_lsa_install(oi->ospf, oi, lsa) == NULL) {
                zlog_warn("%s: ospf_lsa_install() failed", __func__);
                ospf_lsa_unlock(&lsa);
                return;
        }

        /* Update new LSA origination count. */
        oi->ospf->lsa_originate_count++;

        /* Flood the LSA through out the interface */
        ospf_flood_through_interface(oi, NULL, lsa);
}

/* Flush all self-originated Grace-LSAs. */
static void ospf_gr_flush_grace_lsas(struct ospf *ospf)
{
        struct ospf_area *area;
        struct listnode *anode;

        for (ALL_LIST_ELEMENTS_RO(ospf->areas, anode, area)) {
                struct ospf_interface *oi;
                struct listnode *inode;

                if (IS_DEBUG_OSPF_GR)
                        zlog_debug(
                                "GR: flushing self-originated Grace-LSAs [area %pI4]",
                                &area->area_id);

                for (ALL_LIST_ELEMENTS_RO(area->oiflist, inode, oi))
                        ospf_gr_lsa_originate(oi, true);
        }
}

/* Exit from the Graceful Restart mode. */
static void ospf_gr_restart_exit(struct ospf *ospf, const char *reason)
{
        struct ospf_area *area;
        struct listnode *onode, *anode;

        if (IS_DEBUG_OSPF_GR)
                zlog_debug("GR: exiting graceful restart: %s", reason);

        ospf->gr_info.restart_in_progress = false;
        OSPF_TIMER_OFF(ospf->gr_info.t_grace_period);

        /* Record in non-volatile memory that the restart is complete. */
        ospf_gr_nvm_delete(ospf);

        for (ALL_LIST_ELEMENTS_RO(ospf->areas, onode, area)) {
                struct ospf_interface *oi;

                /*
                 * 1) The router should reoriginate its router-LSAs for all
                 *    attached areas in order to make sure they have the correct
                 *    contents.
                 */
                ospf_router_lsa_update_area(area);

                /*
                 * 2) The router should reoriginate network-LSAs on all segments
                 *    where it is the Designated Router.
                 */
                for (ALL_LIST_ELEMENTS_RO(area->oiflist, anode, oi))
                        if (oi->state == ISM_DR)
                                ospf_network_lsa_update(oi);
        }

        /*
         * 5) Any received self-originated LSAs that are no longer valid should
         *    be flushed.
         */
        ospf_schedule_abr_task(ospf);

        /*
         * 3) The router reruns its OSPF routing calculations, this time
         *    installing the results into the system forwarding table, and
         *    originating summary-LSAs, Type-7 LSAs and AS-external-LSAs as
         *    necessary.
         *
         * 4) Any remnant entries in the system forwarding table that were
         *    installed before the restart, but that are no longer valid,
         *    should be removed.
         */
        ospf->gr_info.finishing_restart = true;
        ospf_spf_calculate_schedule(ospf, SPF_FLAG_GR_FINISH);

        /* 6) Any grace-LSAs that the router originated should be flushed. */
        ospf_gr_flush_grace_lsas(ospf);
}

/* Check if a Router-LSA contains a given link. */
static bool ospf_router_lsa_contains_adj(struct ospf_lsa *lsa,
                                         struct in_addr *id)
{
        struct router_lsa *rl;

        rl = (struct router_lsa *)lsa->data;
        for (int i = 0; i < ntohs(rl->links); i++) {
                struct in_addr *link_id = &rl->link[i].link_id;

                if (rl->link[i].type != LSA_LINK_TYPE_POINTOPOINT)
                        continue;

                if (IPV4_ADDR_SAME(id, link_id))
                        return true;
        }

        return false;
}

static bool ospf_gr_check_router_lsa_consistency(struct ospf *ospf,
                                                 struct ospf_area *area,
                                                 struct ospf_lsa *lsa)
{
        if (CHECK_FLAG(lsa->flags, OSPF_LSA_SELF)) {
                struct ospf_lsa *lsa_self = lsa;
                struct router_lsa *rl = (struct router_lsa *)lsa->data;

                for (int i = 0; i < ntohs(rl->links); i++) {
                        struct in_addr *link_id = &rl->link[i].link_id;
                        struct ospf_lsa *lsa_adj;

                        if (rl->link[i].type != LSA_LINK_TYPE_POINTOPOINT)
                                continue;

                        lsa_adj = ospf_lsa_lookup_by_id(area, OSPF_ROUTER_LSA,
                                                        *link_id);
                        if (!lsa_adj)
                                continue;

                        if (!ospf_router_lsa_contains_adj(lsa_adj,
                                                          &lsa_self->data->id))
                                return false;
                }
        } else {
                struct ospf_lsa *lsa_self;

                lsa_self = ospf_lsa_lookup_by_id(area, OSPF_ROUTER_LSA,
                                                 ospf->router_id);
                if (!lsa_self
                    || !CHECK_FLAG(lsa_self->flags, OSPF_LSA_RECEIVED))
                        return true;

                if (ospf_router_lsa_contains_adj(lsa, &ospf->router_id)
                    != ospf_router_lsa_contains_adj(lsa_self, &lsa->data->id))
                        return false;
        }

        return true;
}

/*
 * Check for LSAs that are inconsistent with the pre-restart LSAs, and abort the
 * ongoing graceful restart when that's the case.
 */
void ospf_gr_check_lsdb_consistency(struct ospf *ospf, struct ospf_area *area)
{
        struct route_node *rn;
        struct ospf_lsa *lsa;

        for (rn = route_top(ROUTER_LSDB(area)); rn; rn = route_next(rn)) {
                lsa = rn->info;
                if (!lsa)
                        continue;

                if (!ospf_gr_check_router_lsa_consistency(ospf, area, lsa)) {
                        char reason[256];

                        snprintfrr(reason, sizeof(reason),
                                   "detected inconsistent LSA[%s] [area %pI4]",
                                   dump_lsa_key(lsa), &area->area_id);
                        ospf_gr_restart_exit(ospf, reason);
                        route_unlock_node(rn);
                        return;
                }
        }
}

/* Lookup neighbor by address in a given OSPF area. */
static struct ospf_neighbor *
ospf_area_nbr_lookup_by_addr(struct ospf_area *area, struct in_addr *addr)
{
        struct ospf_interface *oi;
        struct ospf_neighbor *nbr;
        struct listnode *node;

        for (ALL_LIST_ELEMENTS_RO(area->oiflist, node, oi)) {
                nbr = ospf_nbr_lookup_by_addr(oi->nbrs, addr);
                if (nbr)
                        return nbr;
        }

        return NULL;
}

/* Lookup neighbor by Router ID in a given OSPF area. */
static struct ospf_neighbor *
ospf_area_nbr_lookup_by_routerid(struct ospf_area *area, struct in_addr *id)
{
        struct ospf_interface *oi;
        struct ospf_neighbor *nbr;
        struct listnode *node;

        for (ALL_LIST_ELEMENTS_RO(area->oiflist, node, oi)) {
                nbr = ospf_nbr_lookup_by_routerid(oi->nbrs, id);
                if (nbr)
                        return nbr;
        }

        return NULL;
}

/* Check if there's a fully formed adjacency with the given neighbor ID. */
static bool ospf_gr_check_adj_id(struct ospf_area *area,
                                 struct in_addr *nbr_id)
{
        struct ospf_neighbor *nbr;

        nbr = ospf_area_nbr_lookup_by_routerid(area, nbr_id);
        if (!nbr || nbr->state < NSM_Full) {
                if (IS_DEBUG_OSPF_GR)
                        zlog_debug("GR: missing adjacency to router %pI4",
                                   nbr_id);
                return false;
        }

        return true;
}

static bool ospf_gr_check_adjs_lsa_transit(struct ospf_area *area,
                                           struct in_addr *link_id)
{
        struct ospf *ospf = area->ospf;
        struct ospf_interface *oi;

        /*
         * Check if the transit network refers to a local interface (in which
         * case it must be a DR for that network).
         */
        oi = ospf_if_lookup_by_local_addr(ospf, NULL, *link_id);
        if (oi) {
                struct ospf_lsa *lsa;
                struct network_lsa *nlsa;
                size_t cnt;

                /* Lookup Network LSA corresponding to this interface. */
                lsa = ospf_lsa_lookup_by_id(area, OSPF_NETWORK_LSA, *link_id);
                if (!lsa)
                        return false;

                /* Iterate over all routers present in the network. */
                nlsa = (struct network_lsa *)lsa->data;
                cnt = (lsa->size - (OSPF_LSA_HEADER_SIZE + 4)) / 4;
                for (size_t i = 0; i < cnt; i++) {
                        struct in_addr *nbr_id = &nlsa->routers[i];

                        /* Skip self in the pseudonode. */
                        if (IPV4_ADDR_SAME(nbr_id, &ospf->router_id))
                                continue;

                        /*
                         * Check if there's a fully formed adjacency with this
                         * router.
                         */
                        if (!ospf_gr_check_adj_id(area, nbr_id))
                                return false;
                }
        } else {
                struct ospf_neighbor *nbr;

                /* Check if there's a fully formed adjacency with the DR. */
                nbr = ospf_area_nbr_lookup_by_addr(area, link_id);
                if (!nbr || nbr->state < NSM_Full) {
                        if (IS_DEBUG_OSPF_GR)
                                zlog_debug(
                                        "GR: missing adjacency to DR router %pI4",
                                        link_id);
                        return false;
                }
        }

        return true;
}

static bool ospf_gr_check_adjs_lsa(struct ospf_area *area, struct ospf_lsa *lsa)
{
        struct router_lsa *rl = (struct router_lsa *)lsa->data;

        for (int i = 0; i < ntohs(rl->links); i++) {
                struct in_addr *link_id = &rl->link[i].link_id;

                switch (rl->link[i].type) {
                case LSA_LINK_TYPE_POINTOPOINT:
                        if (!ospf_gr_check_adj_id(area, link_id))
                                return false;
                        break;
                case LSA_LINK_TYPE_TRANSIT:
                        if (!ospf_gr_check_adjs_lsa_transit(area, link_id))
                                return false;
                        break;
                default:
                        break;
                }
        }

        return true;
}

/*
 * Check if all adjacencies prior to the restart were reestablished.
 *
 * This is done using pre-restart Router LSAs and pre-restart Network LSAs
 * received from the helping neighbors.
 */
void ospf_gr_check_adjs(struct ospf *ospf)
{
        struct ospf_area *area;
        struct listnode *node;

        for (ALL_LIST_ELEMENTS_RO(ospf->areas, node, area)) {
                struct ospf_lsa *lsa_self;

                lsa_self = ospf_lsa_lookup_by_id(area, OSPF_ROUTER_LSA,
                                                 ospf->router_id);
                if (!lsa_self || !ospf_gr_check_adjs_lsa(area, lsa_self)) {
                        if (IS_DEBUG_OSPF_GR)
                                zlog_debug(
                                        "GR: not all adjacencies were reestablished yet [area %pI4]",
                                        &area->area_id);
                        return;
                }
        }

        ospf_gr_restart_exit(ospf, "all adjacencies were reestablished");
}

/* Handling of grace period expiry. */
static void ospf_gr_grace_period_expired(struct thread *thread)
{
        struct ospf *ospf = THREAD_ARG(thread);

        ospf->gr_info.t_grace_period = NULL;
        ospf_gr_restart_exit(ospf, "grace period has expired");
}

/*
 * Returns the path of the file (non-volatile memory) that contains GR status
 * information.
 */
static char *ospf_gr_nvm_filepath(struct ospf *ospf)
{
        static char filepath[MAXPATHLEN];
        char instance[16] = "";

        if (ospf->instance)
                snprintf(instance, sizeof(instance), "-%d", ospf->instance);
        snprintf(filepath, sizeof(filepath), OSPFD_GR_STATE, instance);
        return filepath;
}

/*
 * Record in non-volatile memory that the given OSPF instance is attempting to
 * perform a graceful restart.
 */
static void ospf_gr_nvm_update(struct ospf *ospf)
{
        char *filepath;
        const char *inst_name;
        json_object *json;
        json_object *json_instances;
        json_object *json_instance;

        filepath = ospf_gr_nvm_filepath(ospf);
        inst_name = ospf_get_name(ospf);

        json = json_object_from_file(filepath);
        if (json == NULL)
                json = json_object_new_object();

        json_object_object_get_ex(json, "instances", &json_instances);
        if (!json_instances) {
                json_instances = json_object_new_object();
                json_object_object_add(json, "instances", json_instances);
        }

        json_object_object_get_ex(json_instances, inst_name, &json_instance);
        if (!json_instance) {
                json_instance = json_object_new_object();
                json_object_object_add(json_instances, inst_name,
                                       json_instance);
        }

        /*
         * Record not only the grace period, but also a UNIX timestamp
         * corresponding to the end of that period. That way, once ospfd is
         * restarted, it will be possible to take into account the time that
         * passed while ospfd wasn't running.
         */
        json_object_int_add(json_instance, "gracePeriod",
                            ospf->gr_info.grace_period);
        json_object_int_add(json_instance, "timestamp",
                            time(NULL) + ospf->gr_info.grace_period);

        json_object_to_file_ext(filepath, json, JSON_C_TO_STRING_PRETTY);
        json_object_free(json);
}

/*
 * Delete GR status information about the given OSPF instance from non-volatile
 * memory.
 */
static void ospf_gr_nvm_delete(struct ospf *ospf)
{
        char *filepath;
        const char *inst_name;
        json_object *json;
        json_object *json_instances;

        filepath = ospf_gr_nvm_filepath(ospf);
        inst_name = ospf_get_name(ospf);

        json = json_object_from_file(filepath);
        if (json == NULL)
                json = json_object_new_object();

        json_object_object_get_ex(json, "instances", &json_instances);
        if (!json_instances) {
                json_instances = json_object_new_object();
                json_object_object_add(json, "instances", json_instances);
        }

        json_object_object_del(json_instances, inst_name);

        json_object_to_file_ext(filepath, json, JSON_C_TO_STRING_PRETTY);
        json_object_free(json);
}

/*
 * Fetch from non-volatile memory whether the given OSPF instance is performing
 * a graceful shutdown or not.
 */
void ospf_gr_nvm_read(struct ospf *ospf)
{
        char *filepath;
        const char *inst_name;
        json_object *json;
        json_object *json_instances;
        json_object *json_instance;
        json_object *json_timestamp;
        time_t timestamp = 0;

        filepath = ospf_gr_nvm_filepath(ospf);
        inst_name = ospf_get_name(ospf);

        json = json_object_from_file(filepath);
        if (json == NULL)
                json = json_object_new_object();

        json_object_object_get_ex(json, "instances", &json_instances);
        if (!json_instances) {
                json_instances = json_object_new_object();
                json_object_object_add(json, "instances", json_instances);
        }

        json_object_object_get_ex(json_instances, inst_name, &json_instance);
        if (!json_instance) {
                json_instance = json_object_new_object();
                json_object_object_add(json_instances, inst_name,
                                       json_instance);
        }

        json_object_object_get_ex(json_instance, "timestamp", &json_timestamp);
        if (json_timestamp) {
                time_t now;
                unsigned long remaining_time;

                /* Check if the grace period has already expired. */
                now = time(NULL);
                timestamp = json_object_get_int(json_timestamp);
                if (now > timestamp) {
                        ospf_gr_restart_exit(
                                ospf, "grace period has expired already");
                } else {
                        /* Schedule grace period timeout. */
                        ospf->gr_info.restart_in_progress = true;
                        remaining_time = timestamp - time(NULL);
                        if (IS_DEBUG_OSPF_GR)
                                zlog_debug(
                                        "GR: remaining time until grace period expires: %lu(s)",
                                        remaining_time);
                        thread_add_timer(master, ospf_gr_grace_period_expired,
                                         ospf, remaining_time,
                                         &ospf->gr_info.t_grace_period);
                }
        }

        json_object_object_del(json_instances, inst_name);

        json_object_to_file_ext(filepath, json, JSON_C_TO_STRING_PRETTY);
        json_object_free(json);
}

/* Prepare to start a Graceful Restart. */
static void ospf_gr_prepare(void)
{
        struct ospf *ospf;
        struct ospf_interface *oi;
        struct listnode *onode;

        for (ALL_LIST_ELEMENTS_RO(om->ospf, onode, ospf)) {
                struct listnode *inode;

                if (!ospf->gr_info.restart_support
                    || ospf->gr_info.prepare_in_progress)
                        continue;

                if (IS_DEBUG_OSPF_GR)
                        zlog_debug(
                                "GR: preparing to perform a graceful restart [period %u second(s)] [vrf %s]",
                                ospf->gr_info.grace_period,
                                ospf_vrf_id_to_name(ospf->vrf_id));

                if (!CHECK_FLAG(ospf->config, OSPF_OPAQUE_CAPABLE)) {
                        zlog_warn(
                                "%s: failed to activate graceful restart: opaque capability not enabled",
                                __func__);
                        continue;
                }

                /* Freeze OSPF routes in the RIB. */
                if (ospf_zebra_gr_enable(ospf, ospf->gr_info.grace_period)) {
                        zlog_warn(
                                "%s: failed to activate graceful restart: not connected to zebra",
                                __func__);
                        continue;
                }

                /* Send a Grace-LSA to all neighbors. */
                for (ALL_LIST_ELEMENTS_RO(ospf->oiflist, inode, oi))
                        ospf_gr_lsa_originate(oi, false);

                /* Record end of the grace period in non-volatile memory. */
                ospf_gr_nvm_update(ospf);

                /*
                 * Mark that a Graceful Restart preparation is in progress, to
                 * prevent ospfd from flushing its self-originated LSAs on exit.
                 */
                ospf->gr_info.prepare_in_progress = true;
        }
}

DEFPY(graceful_restart_prepare, graceful_restart_prepare_cmd,
      "graceful-restart prepare ip ospf",
      "Graceful Restart commands\n"
      "Prepare upcoming graceful restart\n"
      IP_STR
      "Prepare to restart the OSPF process\n")
{
        struct ospf *ospf;
        struct listnode *node;

        for (ALL_LIST_ELEMENTS_RO(om->ospf, node, ospf)) {
                if (!CHECK_FLAG(ospf->config, OSPF_OPAQUE_CAPABLE)) {
                        vty_out(vty,
                                "%% Can't start graceful restart: opaque capability not enabled (VRF %s)\n\n",
                                ospf_get_name(ospf));
                        return CMD_WARNING;
                }
        }

        ospf_gr_prepare();

        return CMD_SUCCESS;
}

DEFPY(graceful_restart, graceful_restart_cmd,
      "graceful-restart [grace-period (1-1800)$grace_period]",
      OSPF_GR_STR
      "Maximum length of the 'grace period'\n"
      "Maximum length of the 'grace period' in seconds\n")
{
        VTY_DECLVAR_INSTANCE_CONTEXT(ospf, ospf);

        /* Check and get restart period if present. */
        if (!grace_period_str)
                grace_period = OSPF_DFLT_GRACE_INTERVAL;

        ospf->gr_info.restart_support = true;
        ospf->gr_info.grace_period = grace_period;

        return CMD_SUCCESS;
}

DEFPY(no_graceful_restart, no_graceful_restart_cmd,
      "no graceful-restart [grace-period (1-1800)]",
      NO_STR OSPF_GR_STR
      "Maximum length of the 'grace period'\n"
      "Maximum length of the 'grace period' in seconds\n")
{
        VTY_DECLVAR_INSTANCE_CONTEXT(ospf, ospf);

        if (!ospf->gr_info.restart_support)
                return CMD_SUCCESS;

        if (ospf->gr_info.prepare_in_progress) {
                vty_out(vty,
                        "%% Error: Graceful Restart preparation in progress\n");
                return CMD_WARNING;
        }

        ospf->gr_info.restart_support = false;
        ospf->gr_info.grace_period = OSPF_DFLT_GRACE_INTERVAL;

        return CMD_SUCCESS;
}

void ospf_gr_init(void)
{
        install_element(ENABLE_NODE, &graceful_restart_prepare_cmd);
        install_element(OSPF_NODE, &graceful_restart_cmd);
        install_element(OSPF_NODE, &no_graceful_restart_cmd);
}