// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OSPF Neighbor functions.
 * Copyright (C) 1999, 2000 Toshiaki Takada
 */

#include <zebra.h>

#include "lib/bfd.h"
#include "linklist.h"
#include "prefix.h"
#include "memory.h"
#include "command.h"
#include "frrevent.h"
#include "stream.h"
#include "table.h"
#include "log.h"
#include "json.h"

#include "ospfd/ospfd.h"
#include "ospfd/ospf_interface.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_packet.h"
#include "ospfd/ospf_network.h"
#include "ospfd/ospf_flood.h"
#include "ospfd/ospf_dump.h"
#include "ospfd/ospf_bfd.h"
#include "ospfd/ospf_gr.h"

/* Fill in the the 'key' as appropriate to retrieve the entry for nbr
 * from the ospf_interface's nbrs table. Indexed by interface address
 * for all cases except Virtual-link and PointToPoint interfaces, where
 * neighbours are indexed by router-ID instead.
 */
static void ospf_nbr_key(struct ospf_interface *oi, struct ospf_neighbor *nbr,
			 struct prefix *key)
{
	key->family = AF_INET;
	key->prefixlen = IPV4_MAX_BITLEN;

	/* vlinks are indexed by router-id */
	if (oi->type == OSPF_IFTYPE_VIRTUALLINK
	    || oi->type == OSPF_IFTYPE_POINTOPOINT)
		key->u.prefix4 = nbr->router_id;
	else
		key->u.prefix4 = nbr->src;
	return;
}

struct ospf_neighbor *ospf_nbr_new(struct ospf_interface *oi)
{
	struct ospf_neighbor *nbr;

	/* Allcate new neighbor. */
	nbr = XCALLOC(MTYPE_OSPF_NEIGHBOR, sizeof(struct ospf_neighbor));

	/* Relate neighbor to the interface. */
	nbr->oi = oi;

	/* Set default values. */
	nbr->state = NSM_Down;

	/* Set inheritance values. */
	nbr->v_inactivity = OSPF_IF_PARAM(oi, v_wait);
	nbr->v_db_desc = OSPF_IF_PARAM(oi, retransmit_interval);
	nbr->v_ls_req = OSPF_IF_PARAM(oi, retransmit_interval);
	nbr->v_ls_rxmt = OSPF_IF_PARAM(oi, retransmit_interval);
	nbr->priority = -1;

	/* DD flags. */
	nbr->dd_flags = OSPF_DD_FLAG_MS | OSPF_DD_FLAG_M | OSPF_DD_FLAG_I;

	/* Last received and sent DD. */
	nbr->last_send = NULL;

	nbr->nbr_nbma = NULL;

	ospf_lsdb_init(&nbr->db_sum);

	ospf_lsdb_linked_init(&nbr->ls_rxmt);
	ospf_lsdb_init(&nbr->ls_req);
	ospf_lsa_list_init(&nbr->ls_rxmt_list);

	nbr->crypt_seqnum = 0;

	/* Initialize GR Helper info*/
	nbr->gr_helper_info.recvd_grace_period = 0;
	nbr->gr_helper_info.actual_grace_period = 0;
	nbr->gr_helper_info.gr_helper_status = OSPF_GR_NOT_HELPER;
	nbr->gr_helper_info.helper_exit_reason = OSPF_GR_HELPER_EXIT_NONE;
	nbr->gr_helper_info.gr_restart_reason = OSPF_GR_UNKNOWN_RESTART;

	return nbr;
}

void ospf_nbr_free(struct ospf_neighbor *nbr)
{
	/* Free DB summary list. */
	if (ospf_db_summary_count(nbr))
		ospf_db_summary_clear(nbr);
	/* ospf_db_summary_delete_all (nbr); */

	/* Free ls request list. */
	if (ospf_ls_request_count(nbr))
		ospf_ls_request_delete_all(nbr);

	/* Free retransmit list. */
	if (ospf_ls_retransmit_count(nbr))
		ospf_ls_retransmit_clear(nbr);

	/* Cleanup LSDBs. */
	ospf_lsdb_cleanup(&nbr->db_sum);
	ospf_lsdb_cleanup(&nbr->ls_req);
	ospf_lsdb_cleanup(&nbr->ls_rxmt);

	/* Clear last send packet. */
	if (nbr->last_send)
		ospf_packet_free(nbr->last_send);

	if (nbr->nbr_nbma) {
		nbr->nbr_nbma->nbr = NULL;
		nbr->nbr_nbma = NULL;
	}

	/* Cancel all timers. */
	EVENT_OFF(nbr->t_inactivity);
	EVENT_OFF(nbr->t_db_desc);
	EVENT_OFF(nbr->t_ls_req);
	EVENT_OFF(nbr->t_ls_rxmt);

	/* Cancel all events. */ /* Thread lookup cost would be negligible. */
	event_cancel_event(master, nbr);

	bfd_sess_free(&nbr->bfd_session);

	EVENT_OFF(nbr->gr_helper_info.t_grace_timer);

	nbr->oi = NULL;
	XFREE(MTYPE_OSPF_NEIGHBOR, nbr);
}

/* Delete specified OSPF neighbor from interface. */
void ospf_nbr_delete(struct ospf_neighbor *nbr)
{
	struct ospf_interface *oi;
	struct route_node *rn;
	struct prefix p;

	oi = nbr->oi;

	/* get appropriate prefix 'key' */
	ospf_nbr_key(oi, nbr, &p);

	rn = route_node_lookup(oi->nbrs, &p);
	if (rn) {
		/* If lookup for a NBR succeeds, the leaf route_node could
		 * only exist because there is (or was) a nbr there.
		 * If the nbr was deleted, the leaf route_node should have
		 * lost its last refcount too, and be deleted.
		 * Therefore a looked-up leaf route_node in nbrs table
		 * should never have NULL info.
		 */
		assert(rn->info);

		if (rn->info) {
			rn->info = NULL;
			route_unlock_node(rn);
		} else
			zlog_info("Can't find neighbor %pI4 in the interface %s",
				  &nbr->src, IF_NAME(oi));

		route_unlock_node(rn);
	} else {
		/*
		 * This neighbor was not found, but before we move on and
		 * free the neighbor structre, make sure that it was not
		 * indexed incorrectly and ended up in the "worng" place
		 */

		/* Reverse the lookup rules */
		if (oi->type == OSPF_IFTYPE_VIRTUALLINK
		    || oi->type == OSPF_IFTYPE_POINTOPOINT)
			p.u.prefix4 = nbr->src;
		else
			p.u.prefix4 = nbr->router_id;

		rn = route_node_lookup(oi->nbrs, &p);
		if (rn) {
			/* We found the neighbor!
			 * Now make sure it is not the exact same neighbor
			 * structure that we are about to free
			 */
			if (nbr == rn->info) {
				/* Same neighbor, drop the reference to it */
				rn->info = NULL;
				route_unlock_node(rn);
			}
			route_unlock_node(rn);
		}
	}

	/* Free ospf_neighbor structure. */
	ospf_nbr_free(nbr);
}

/* Check myself is in the neighbor list. */
int ospf_nbr_bidirectional(struct in_addr *router_id, struct in_addr *neighbors,
			   int size)
{
	int i;
	int max;

	max = size / sizeof(struct in_addr);

	for (i = 0; i < max; i++)
		if (IPV4_ADDR_SAME(router_id, &neighbors[i]))
			return 1;

	return 0;
}

/* reset nbr_self */
void ospf_nbr_self_reset(struct ospf_interface *oi, struct in_addr router_id)
{
	if (oi->nbr_self)
		ospf_nbr_delete(oi->nbr_self);

	oi->nbr_self = ospf_nbr_new(oi);
	ospf_nbr_add_self(oi, router_id);
}

/* Add self to nbr list. */
void ospf_nbr_add_self(struct ospf_interface *oi, struct in_addr router_id)
{
	struct prefix p;
	struct route_node *rn;

	if (!oi->nbr_self)
		oi->nbr_self = ospf_nbr_new(oi);

	/* Initial state */
	oi->nbr_self->address = *oi->address;
	oi->nbr_self->priority = OSPF_IF_PARAM(oi, priority);
	oi->nbr_self->router_id = router_id;
	oi->nbr_self->src = oi->address->u.prefix4;
	oi->nbr_self->state = NSM_TwoWay;

	switch (oi->area->external_routing) {
	case OSPF_AREA_DEFAULT:
		SET_FLAG(oi->nbr_self->options, OSPF_OPTION_E);
		break;
	case OSPF_AREA_STUB:
		UNSET_FLAG(oi->nbr_self->options, OSPF_OPTION_E);
		break;
	case OSPF_AREA_NSSA:
		UNSET_FLAG(oi->nbr_self->options, OSPF_OPTION_E);
		SET_FLAG(oi->nbr_self->options, OSPF_OPTION_NP);
		break;
	}

	/* Add nbr_self to nbrs table */
	ospf_nbr_key(oi, oi->nbr_self, &p);

	rn = route_node_get(oi->nbrs, &p);
	if (rn->info) {
		/* There is already pseudo neighbor. */
		if (IS_DEBUG_OSPF_EVENT)
			zlog_debug(
				"router_id %pI4 already present in neighbor table. node refcount %u",
				&router_id, route_node_get_lock_count(rn));
		route_unlock_node(rn);
	} else
		rn->info = oi->nbr_self;
}

/* Get neighbor count by status.
   Specify status = 0, get all neighbor other than myself. */
int ospf_nbr_count(struct ospf_interface *oi, int state)
{
	struct ospf_neighbor *nbr;
	struct route_node *rn;
	int count = 0;

	for (rn = route_top(oi->nbrs); rn; rn = route_next(rn))
		if ((nbr = rn->info))
			if (!IPV4_ADDR_SAME(&nbr->router_id,
					    &oi->ospf->router_id))
				if (state == 0 || nbr->state == state)
					count++;

	return count;
}

int ospf_nbr_count_opaque_capable(struct ospf_interface *oi)
{
	struct ospf_neighbor *nbr;
	struct route_node *rn;
	int count = 0;

	for (rn = route_top(oi->nbrs); rn; rn = route_next(rn))
		if ((nbr = rn->info))
			if (!IPV4_ADDR_SAME(&nbr->router_id,
					    &oi->ospf->router_id))
				if (nbr->state == NSM_Full)
					if (CHECK_FLAG(nbr->options,
						       OSPF_OPTION_O))
						count++;

	return count;
}

/* lookup nbr by address - use this only if you know you must
 * otherwise use the ospf_nbr_lookup() wrapper, which deals
 * with virtual link and PointToPoint neighbours
 */
struct ospf_neighbor *ospf_nbr_lookup_by_addr(struct route_table *nbrs,
					      struct in_addr *addr)
{
	struct prefix p;
	struct route_node *rn;
	struct ospf_neighbor *nbr;

	p.family = AF_INET;
	p.prefixlen = IPV4_MAX_BITLEN;
	p.u.prefix4 = *addr;

	rn = route_node_lookup(nbrs, &p);
	if (!rn)
		return NULL;

	/* See comment in ospf_nbr_delete */
	assert(rn->info);

	if (rn->info == NULL) {
		route_unlock_node(rn);
		return NULL;
	}

	nbr = (struct ospf_neighbor *)rn->info;
	route_unlock_node(rn);

	return nbr;
}

struct ospf_neighbor *ospf_nbr_lookup_by_routerid(struct route_table *nbrs,
						  struct in_addr *id)
{
	struct route_node *rn;
	struct ospf_neighbor *nbr;

	for (rn = route_top(nbrs); rn; rn = route_next(rn))
		if ((nbr = rn->info) != NULL)
			if (IPV4_ADDR_SAME(&nbr->router_id, id)) {
				route_unlock_node(rn);
				return nbr;
			}

	return NULL;
}

void ospf_renegotiate_optional_capabilities(struct ospf *top)
{
	struct listnode *node;
	struct ospf_interface *oi;
	struct route_table *nbrs;
	struct route_node *rn;
	struct ospf_neighbor *nbr;
	uint8_t shutdown_save = top->inst_shutdown;

	/* At first, flush self-originated LSAs from routing domain. */
	ospf_flush_self_originated_lsas_now(top);

	/* ospf_flush_self_originated_lsas_now is primarily intended for shut
	 * down scenarios. Reset the inst_shutdown flag that it sets. We are
	 * just changing configuration, and the flag can change the scheduling
	 * of when maxage LSAs are sent. */
	top->inst_shutdown = shutdown_save;

	/* Revert all neighbor status to ExStart. */
	for (ALL_LIST_ELEMENTS_RO(top->oiflist, node, oi)) {
		if ((nbrs = oi->nbrs) == NULL)
			continue;

		for (rn = route_top(nbrs); rn; rn = route_next(rn)) {
			if ((nbr = rn->info) == NULL || nbr == oi->nbr_self)
				continue;

			if (nbr->state < NSM_ExStart)
				continue;

			if (IS_DEBUG_OSPF_EVENT)
				zlog_debug(
					"Renegotiate optional capabilities with neighbor(%pI4)",
					&nbr->router_id);

			OSPF_NSM_EVENT_SCHEDULE(nbr, NSM_SeqNumberMismatch);
		}
	}

	/* Refresh/Re-originate external LSAs (Type-7 and Type-5).*/
	ospf_external_lsa_rid_change(top);

	return;
}


struct ospf_neighbor *ospf_nbr_lookup(struct ospf_interface *oi, struct ip *iph,
				      struct ospf_header *ospfh)
{
	struct in_addr srcaddr = iph->ip_src;

	if (oi->type == OSPF_IFTYPE_VIRTUALLINK
	    || oi->type == OSPF_IFTYPE_POINTOPOINT)
		return (ospf_nbr_lookup_by_routerid(oi->nbrs,
						    &ospfh->router_id));
	else
		return (ospf_nbr_lookup_by_addr(oi->nbrs, &srcaddr));
}

static struct ospf_neighbor *ospf_nbr_add(struct ospf_interface *oi,
					  struct ospf_header *ospfh,
					  struct prefix *p)
{
	struct ospf_neighbor *nbr;

	nbr = ospf_nbr_new(oi);
	nbr->state = NSM_Down;
	nbr->src = p->u.prefix4;
	memcpy(&nbr->address, p, sizeof(struct prefix));

	nbr->nbr_nbma = NULL;
	if (OSPF_IF_NON_BROADCAST(oi)) {
		struct ospf_nbr_nbma *nbr_nbma;
		struct listnode *node;

		for (ALL_LIST_ELEMENTS_RO(oi->nbr_nbma, node, nbr_nbma)) {
			if (IPV4_ADDR_SAME(&nbr_nbma->addr, &nbr->src)) {
				nbr_nbma->nbr = nbr;
				nbr->nbr_nbma = nbr_nbma;

				if (nbr_nbma->t_poll)
					EVENT_OFF(nbr_nbma->t_poll);

				nbr->state_change = nbr_nbma->state_change + 1;
			}
		}
	}

	/* New nbr, save the crypto sequence number if necessary */
	if (ntohs(ospfh->auth_type) == OSPF_AUTH_CRYPTOGRAPHIC)
		nbr->crypt_seqnum = ospfh->u.crypt.crypt_seqnum;

	/* Configure BFD if interface has it. */
	ospf_neighbor_bfd_apply(nbr);

	if (IS_DEBUG_OSPF_EVENT)
		zlog_debug("NSM[%s:%pI4]: start", IF_NAME(oi),
			   &nbr->router_id);

	return nbr;
}

struct ospf_neighbor *ospf_nbr_get(struct ospf_interface *oi,
				   struct ospf_header *ospfh, struct ip *iph,
				   struct prefix *p)
{
	struct route_node *rn;
	struct prefix key;
	struct ospf_neighbor *nbr;

	key.family = AF_INET;
	key.prefixlen = IPV4_MAX_BITLEN;

	if (oi->type == OSPF_IFTYPE_VIRTUALLINK
	    || oi->type == OSPF_IFTYPE_POINTOPOINT)
		key.u.prefix4 = ospfh->router_id; /* index vlink and ptp nbrs by
						     router-id */
	else
		key.u.prefix4 = iph->ip_src;

	rn = route_node_get(oi->nbrs, &key);
	if (rn->info) {
		route_unlock_node(rn);
		nbr = rn->info;

		if (OSPF_IF_NON_BROADCAST(nbr->oi) && nbr->state == NSM_Attempt) {
			nbr->src = iph->ip_src;
			memcpy(&nbr->address, p, sizeof(struct prefix));
		}
	} else {
		rn->info = nbr = ospf_nbr_add(oi, ospfh, p);
	}

	nbr->router_id = ospfh->router_id;

	return nbr;
}