/*
 * Zebra neighbor table management
 *
 * Copyright (C) 2021 Nvidia
 * Anuradha Karuppiah
 *
 * This file is part of FRR.
 *
 * FRR 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.
 *
 * FRR 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.
 */

#include <zebra.h>

#include "command.h"
#include "hash.h"
#include "if.h"
#include "jhash.h"
#include "linklist.h"
#include "log.h"
#include "memory.h"
#include "prefix.h"
#include "stream.h"
#include "table.h"

#include "zebra/zebra_router.h"
#include "zebra/debug.h"
#include "zebra/interface.h"
#include "zebra/rib.h"
#include "zebra/rt.h"
#include "zebra/rt_netlink.h"
#include "zebra/zebra_errors.h"
#include "zebra/interface.h"
#include "zebra/zebra_neigh.h"
#include "zebra/zebra_pbr.h"

DEFINE_MTYPE_STATIC(ZEBRA, ZNEIGH_INFO, "Zebra neigh table");
DEFINE_MTYPE_STATIC(ZEBRA, ZNEIGH_ENT, "Zebra neigh entry");

static int zebra_neigh_rb_cmp(const struct zebra_neigh_ent *n1,
			      const struct zebra_neigh_ent *n2)
{
	if (n1->ifindex < n2->ifindex)
		return -1;

	if (n1->ifindex > n2->ifindex)
		return 1;

	if (n1->ip.ipa_type < n2->ip.ipa_type)
		return -1;

	if (n1->ip.ipa_type > n2->ip.ipa_type)
		return 1;

	if (n1->ip.ipa_type == AF_INET) {
		if (n1->ip.ipaddr_v4.s_addr < n2->ip.ipaddr_v4.s_addr)
			return -1;

		if (n1->ip.ipaddr_v4.s_addr > n2->ip.ipaddr_v4.s_addr)
			return 1;

		return 0;
	}

	return memcmp(&n1->ip.ipaddr_v6, &n2->ip.ipaddr_v6, IPV6_MAX_BYTELEN);
}
RB_GENERATE(zebra_neigh_rb_head, zebra_neigh_ent, rb_node, zebra_neigh_rb_cmp);

static struct zebra_neigh_ent *zebra_neigh_find(ifindex_t ifindex,
						struct ipaddr *ip)
{
	struct zebra_neigh_ent tmp;

	tmp.ifindex = ifindex;
	memcpy(&tmp.ip, ip, sizeof(*ip));
	return RB_FIND(zebra_neigh_rb_head, &zneigh_info->neigh_rb_tree, &tmp);
}

static struct zebra_neigh_ent *
zebra_neigh_new(ifindex_t ifindex, struct ipaddr *ip, struct ethaddr *mac)
{
	struct zebra_neigh_ent *n;

	n = XCALLOC(MTYPE_ZNEIGH_ENT, sizeof(struct zebra_neigh_ent));

	memcpy(&n->ip, ip, sizeof(*ip));
	n->ifindex = ifindex;
	if (mac) {
		memcpy(&n->mac, mac, sizeof(*mac));
		n->flags |= ZEBRA_NEIGH_ENT_ACTIVE;
	}

	/* Add to rb_tree */
	if (RB_INSERT(zebra_neigh_rb_head, &zneigh_info->neigh_rb_tree, n)) {
		XFREE(MTYPE_ZNEIGH_ENT, n);
		return NULL;
	}

	/* Initialise the pbr rule list */
	n->pbr_rule_list = list_new();
	listset_app_node_mem(n->pbr_rule_list);

	if (IS_ZEBRA_DEBUG_NEIGH)
		zlog_debug("zebra neigh new if %d %pIA %pEA", n->ifindex,
			   &n->ip, &n->mac);

	return n;
}

static void zebra_neigh_pbr_rules_update(struct zebra_neigh_ent *n)
{
	struct zebra_pbr_rule *rule;
	struct listnode *node;

	for (ALL_LIST_ELEMENTS_RO(n->pbr_rule_list, node, rule))
		dplane_pbr_rule_update(rule, rule);
}

static void zebra_neigh_free(struct zebra_neigh_ent *n)
{
	if (listcount(n->pbr_rule_list)) {
		/* if rules are still using the neigh mark it as inactive and
		 * update the dataplane
		 */
		if (n->flags & ZEBRA_NEIGH_ENT_ACTIVE) {
			n->flags &= ~ZEBRA_NEIGH_ENT_ACTIVE;
			memset(&n->mac, 0, sizeof(n->mac));
		}
		zebra_neigh_pbr_rules_update(n);
		return;
	}
	if (IS_ZEBRA_DEBUG_NEIGH)
		zlog_debug("zebra neigh free if %d %pIA %pEA", n->ifindex,
			   &n->ip, &n->mac);

	/* cleanup resources maintained against the neigh */
	list_delete(&n->pbr_rule_list);

	RB_REMOVE(zebra_neigh_rb_head, &zneigh_info->neigh_rb_tree, n);

	XFREE(MTYPE_ZNEIGH_ENT, n);
}

/* kernel neigh del */
void zebra_neigh_del(struct interface *ifp, struct ipaddr *ip)
{
	struct zebra_neigh_ent *n;

	if (IS_ZEBRA_DEBUG_NEIGH)
		zlog_debug("zebra neigh del if %s/%d %pIA", ifp->name,
			   ifp->ifindex, ip);

	n = zebra_neigh_find(ifp->ifindex, ip);
	if (!n)
		return;
	zebra_neigh_free(n);
}

/* kernel neigh add */
void zebra_neigh_add(struct interface *ifp, struct ipaddr *ip,
		     struct ethaddr *mac)
{
	struct zebra_neigh_ent *n;

	if (IS_ZEBRA_DEBUG_NEIGH)
		zlog_debug("zebra neigh add if %s/%d %pIA %pEA", ifp->name,
			   ifp->ifindex, ip, mac);

	n = zebra_neigh_find(ifp->ifindex, ip);
	if (n) {
		if (!memcmp(&n->mac, mac, sizeof(*mac)))
			return;

		memcpy(&n->mac, mac, sizeof(*mac));
		n->flags |= ZEBRA_NEIGH_ENT_ACTIVE;

		/* update rules linked to the neigh */
		zebra_neigh_pbr_rules_update(n);
	} else {
		zebra_neigh_new(ifp->ifindex, ip, mac);
	}
}

void zebra_neigh_deref(struct zebra_pbr_rule *rule)
{
	struct zebra_neigh_ent *n = rule->action.neigh;

	if (IS_ZEBRA_DEBUG_NEIGH)
		zlog_debug("zebra neigh deref if %d %pIA by pbr rule %u",
			   n->ifindex, &n->ip, rule->rule.seq);

	rule->action.neigh = NULL;
	/* remove rule from the list and free if it is inactive */
	list_delete_node(n->pbr_rule_list, &rule->action.neigh_listnode);
	if (!(n->flags & ZEBRA_NEIGH_ENT_ACTIVE))
		zebra_neigh_free(n);
}

/* XXX - this needs to work with evpn's neigh read */
static void zebra_neigh_read_on_first_ref(void)
{
	static bool neigh_read_done;

	if (!neigh_read_done) {
		neigh_read(zebra_ns_lookup(NS_DEFAULT));
		neigh_read_done = true;
	}
}

void zebra_neigh_ref(int ifindex, struct ipaddr *ip,
		     struct zebra_pbr_rule *rule)
{
	struct zebra_neigh_ent *n;

	if (IS_ZEBRA_DEBUG_NEIGH)
		zlog_debug("zebra neigh ref if %d %pIA by pbr rule %u", ifindex,
			   ip, rule->rule.seq);

	zebra_neigh_read_on_first_ref();
	n = zebra_neigh_find(ifindex, ip);
	if (!n)
		n = zebra_neigh_new(ifindex, ip, NULL);

	/* link the pbr entry to the neigh */
	if (rule->action.neigh == n)
		return;

	if (rule->action.neigh)
		zebra_neigh_deref(rule);

	rule->action.neigh = n;
	listnode_init(&rule->action.neigh_listnode, rule);
	listnode_add(n->pbr_rule_list, &rule->action.neigh_listnode);
}

static void zebra_neigh_show_one(struct vty *vty, struct zebra_neigh_ent *n)
{
	char mac_buf[ETHER_ADDR_STRLEN];
	char ip_buf[INET6_ADDRSTRLEN];
	struct interface *ifp;

	ifp = if_lookup_by_index_per_ns(zebra_ns_lookup(NS_DEFAULT),
					n->ifindex);
	ipaddr2str(&n->ip, ip_buf, sizeof(ip_buf));
	prefix_mac2str(&n->mac, mac_buf, sizeof(mac_buf));
	vty_out(vty, "%-20s %-30s %-18s %u\n", ifp ? ifp->name : "-", ip_buf,
		mac_buf, listcount(n->pbr_rule_list));
}

void zebra_neigh_show(struct vty *vty)
{
	struct zebra_neigh_ent *n;

	vty_out(vty, "%-20s %-30s %-18s %s\n", "Interface", "Neighbor", "MAC",
		"#Rules");
	RB_FOREACH (n, zebra_neigh_rb_head, &zneigh_info->neigh_rb_tree)
		zebra_neigh_show_one(vty, n);
}

void zebra_neigh_init(void)
{
	zneigh_info = XCALLOC(MTYPE_ZNEIGH_INFO, sizeof(*zrouter.neigh_info));
	RB_INIT(zebra_neigh_rb_head, &zneigh_info->neigh_rb_tree);
}

void zebra_neigh_terminate(void)
{
	struct zebra_neigh_ent *n, *next;

	if (!zrouter.neigh_info)
		return;

	RB_FOREACH_SAFE (n, zebra_neigh_rb_head, &zneigh_info->neigh_rb_tree,
			 next)
		zebra_neigh_free(n);
	XFREE(MTYPE_ZNEIGH_INFO, zneigh_info);
}