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mirror_frr/ospfd/ospf_gr.h
Renato Westphal 1051417011 ospfd: introduce support for Graceful Restart (restarting mode) 
RFC 3623 specifies the Graceful Restart enhancement to the OSPF
routing protocol. This PR implements support for the restarting mode,
whereas the helper mode was implemented by #6811.

This work is based on #6782, which implemented the pre-restart part
and settled the foundations for the post-restart part (behavioral
changes, GR exit conditions, and on-exit actions).

Here's a quick summary of how the GR restarting mode works:
* GR can be enabled on a per-instance basis using the `graceful-restart
  [grace-period (1-1800)]` command;
* To perform a graceful shutdown, the `graceful-restart prepare ospf`
  EXEC-level command needs to be issued before restarting the ospfd
  daemon (there's no specific requirement on how the daemon should
  be restarted);
* `graceful-restart prepare ospf` will initiate the graceful restart
  for all GR-enabled instances by taking the following actions:
  o Flooding Grace-LSAs over all interfaces
  o Freezing the OSPF routes in the RIB
  o Saving the end of the grace period in non-volatile memory (a JSON
    file stored in `$frr_statedir`)
* Once ospfd is started again, it will follow the procedures
  described in RFC 3623 until it detects it's time to exit the graceful
  restart (either successfully or unsuccessfully).

Testing done:
* New topotest featuring a multi-area OSPF topology (including stub
  and NSSA areas);
* Successful interop tests against IOS-XR routers acting as helpers.

Co-authored-by: GalaxyGorilla <sascha@netdef.org>
Signed-off-by: Renato Westphal <renato@opensourcerouting.org>
2021-07-05 11:43:02 -03:00

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/*
* OSPF Graceful Restart helper functions.
*
* Copyright (C) 2020-21 Vmware, Inc.
* Rajesh Kumar Girada
*
* 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 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
*/
#ifndef _ZEBRA_OSPF_GR_H
#define _ZEBRA_OSPF_GR_H
#define OSPF_GR_NOT_HELPER 0
#define OSPF_GR_ACTIVE_HELPER 1
#define OSPF_GR_HELPER_NO_LSACHECK 0
#define OSPF_GR_HELPER_LSACHECK 1
#define OSPF_MAX_GRACE_INTERVAL 1800
#define OSPF_MIN_GRACE_INTERVAL 1
#define OSPF_DFLT_GRACE_INTERVAL 120
enum ospf_helper_exit_reason {
OSPF_GR_HELPER_EXIT_NONE = 0,
OSPF_GR_HELPER_INPROGRESS,
OSPF_GR_HELPER_TOPO_CHG,
OSPF_GR_HELPER_GRACE_TIMEOUT,
OSPF_GR_HELPER_COMPLETED
};
enum ospf_gr_restart_reason {
OSPF_GR_UNKNOWN_RESTART = 0,
OSPF_GR_SW_RESTART = 1,
OSPF_GR_SW_UPGRADE = 2,
OSPF_GR_SWITCH_REDUNDANT_CARD = 3,
OSPF_GR_INVALID_REASON_CODE = 4
};
enum ospf_gr_helper_rejected_reason {
OSPF_HELPER_REJECTED_NONE,
OSPF_HELPER_SUPPORT_DISABLED,
OSPF_HELPER_NOT_A_VALID_NEIGHBOUR,
OSPF_HELPER_PLANNED_ONLY_RESTART,
OSPF_HELPER_TOPO_CHANGE_RTXMT_LIST,
OSPF_HELPER_LSA_AGE_MORE,
OSPF_HELPER_RESTARTING,
};
/* Ref RFC3623 appendex-A */
/* Grace period TLV */
#define GRACE_PERIOD_TYPE 1
#define GRACE_PERIOD_LENGTH 4
struct grace_tlv_graceperiod {
struct tlv_header header;
uint32_t interval;
};
/* Restart reason TLV */
#define RESTART_REASON_TYPE 2
#define RESTART_REASON_LENGTH 1
struct grace_tlv_restart_reason {
struct tlv_header header;
uint8_t reason;
uint8_t reserved[3];
};
/* Restarter ip address TLV */
#define RESTARTER_IP_ADDR_TYPE 3
#define RESTARTER_IP_ADDR_LEN 4
struct grace_tlv_restart_addr {
struct tlv_header header;
struct in_addr addr;
};
struct ospf_helper_info {
/* Grace interval received from
* Restarting Router.
*/
uint32_t recvd_grace_period;
/* Grace interval used for grace
* gracetimer.
*/
uint32_t actual_grace_period;
/* Grace timer,This Router acts as
* helper until this timer until
* this timer expires.
*/
struct thread *t_grace_timer;
/* Helper status */
uint32_t gr_helper_status;
/* Helper exit reason*/
enum ospf_helper_exit_reason helper_exit_reason;
/* Planned/Unplanned restart*/
enum ospf_gr_restart_reason gr_restart_reason;
/* Helper rejected reason */
enum ospf_gr_helper_rejected_reason rejected_reason;
};
struct advRtr {
struct in_addr advRtrAddr;
};
#define OSPF_HELPER_ENABLE_RTR_COUNT(ospf) (ospf->enable_rtr_list->count)
/* Check for planned restart */
#define OSPF_GR_IS_PLANNED_RESTART(reason) \
((reason == OSPF_GR_SW_RESTART) || (reason == OSPF_GR_SW_UPGRADE))
/* Check the router is HELPER for current neighbour */
#define OSPF_GR_IS_ACTIVE_HELPER(N) \
((N)->gr_helper_info.gr_helper_status == OSPF_GR_ACTIVE_HELPER)
/* Check the LSA is GRACE LSA */
#define IS_GRACE_LSA(lsa) \
((lsa->data->type == OSPF_OPAQUE_LINK_LSA) \
&& (GET_OPAQUE_TYPE(ntohl(lsa->data->id.s_addr)) \
== OPAQUE_TYPE_GRACE_LSA))
/* Check neighbour is in FULL state */
#define IS_NBR_STATE_FULL(nbr) (nsm_should_adj(nbr) && (nbr->state == NSM_Full))
/* Check neighbour is DR_OTHER and state is 2_WAY */
#define IS_NBR_STATE_2_WAY_WITH_DROTHER(nbr) \
((ospf_get_nbr_ism_role(nbr) == ISM_DROther) \
&& (nbr->state == NSM_TwoWay))
#define OSPF_GR_FALSE false
#define OSPF_GR_TRUE true
#define OSPF_GR_SUCCESS 1
#define OSPF_GR_FAILURE 0
#define OSPF_GR_INVALID -1
const char *ospf_exit_reason2str(unsigned int reason);
const char *ospf_restart_reason2str(unsigned int reason);
const char *ospf_rejected_reason2str(unsigned int reason);
extern void ospf_gr_helper_instance_init(struct ospf *ospf);
extern void ospf_gr_helper_instance_stop(struct ospf *ospf);
extern void ospf_gr_helper_init(void);
extern void ospf_gr_helper_stop(void);
extern int ospf_process_grace_lsa(struct ospf *ospf, struct ospf_lsa *lsa,
struct ospf_neighbor *nbr);
extern void ospf_gr_helper_exit(struct ospf_neighbor *nbr,
enum ospf_helper_exit_reason reason);
extern void ospf_process_maxage_grace_lsa(struct ospf *ospf,
struct ospf_lsa *lsa,
struct ospf_neighbor *nbr);
extern void ospf_helper_handle_topo_chg(struct ospf *ospf,
struct ospf_lsa *lsa);
extern void ospf_gr_helper_support_set(struct ospf *ospf, bool support);
extern void ospf_gr_helper_support_set_per_routerid(struct ospf *ospf,
struct in_addr *rid,
bool support);
extern void ospf_gr_helper_lsa_check_set(struct ospf *ospf, bool lsacheck);
extern void ospf_gr_helper_supported_gracetime_set(struct ospf *ospf,
uint32_t interval);
extern void ospf_gr_helper_set_supported_planned_only_restart(struct ospf *ospf,
bool planned_only);
extern void ospf_gr_check_lsdb_consistency(struct ospf *ospf,
struct ospf_area *area);
extern void ospf_gr_check_adjs(struct ospf *ospf);
extern void ospf_gr_nvm_read(struct ospf *ospf);
extern void ospf_gr_init(void);
#endif /* _ZEBRA_OSPF_GR_H */
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