/*
 * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>

struct nft_rbtree {
	struct rb_root		root;
	rwlock_t		lock;
	seqcount_t		count;
};

struct nft_rbtree_elem {
	struct rb_node		node;
	struct nft_set_ext	ext;
};

static bool nft_rbtree_interval_end(const struct nft_rbtree_elem *rbe)
{
	return nft_set_ext_exists(&rbe->ext, NFT_SET_EXT_FLAGS) &&
	       (*nft_set_ext_flags(&rbe->ext) & NFT_SET_ELEM_INTERVAL_END);
}

static bool nft_rbtree_equal(const struct nft_set *set, const void *this,
			     const struct nft_rbtree_elem *interval)
{
	return memcmp(this, nft_set_ext_key(&interval->ext), set->klen) == 0;
}

static bool __nft_rbtree_lookup(const struct net *net, const struct nft_set *set,
				const u32 *key, const struct nft_set_ext **ext,
				unsigned int seq)
{
	struct nft_rbtree *priv = nft_set_priv(set);
	const struct nft_rbtree_elem *rbe, *interval = NULL;
	u8 genmask = nft_genmask_cur(net);
	const struct rb_node *parent;
	const void *this;
	int d;

	parent = rcu_dereference_raw(priv->root.rb_node);
	while (parent != NULL) {
		if (read_seqcount_retry(&priv->count, seq))
			return false;

		rbe = rb_entry(parent, struct nft_rbtree_elem, node);

		this = nft_set_ext_key(&rbe->ext);
		d = memcmp(this, key, set->klen);
		if (d < 0) {
			parent = rcu_dereference_raw(parent->rb_left);
			if (interval &&
			    nft_rbtree_equal(set, this, interval) &&
			    nft_rbtree_interval_end(this) &&
			    !nft_rbtree_interval_end(interval))
				continue;
			interval = rbe;
		} else if (d > 0)
			parent = rcu_dereference_raw(parent->rb_right);
		else {
			if (!nft_set_elem_active(&rbe->ext, genmask)) {
				parent = rcu_dereference_raw(parent->rb_left);
				continue;
			}
			if (nft_rbtree_interval_end(rbe))
				goto out;

			*ext = &rbe->ext;
			return true;
		}
	}

	if (set->flags & NFT_SET_INTERVAL && interval != NULL &&
	    nft_set_elem_active(&interval->ext, genmask) &&
	    !nft_rbtree_interval_end(interval)) {
		*ext = &interval->ext;
		return true;
	}
out:
	return false;
}

static bool nft_rbtree_lookup(const struct net *net, const struct nft_set *set,
			      const u32 *key, const struct nft_set_ext **ext)
{
	struct nft_rbtree *priv = nft_set_priv(set);
	unsigned int seq = read_seqcount_begin(&priv->count);
	bool ret;

	ret = __nft_rbtree_lookup(net, set, key, ext, seq);
	if (ret || !read_seqcount_retry(&priv->count, seq))
		return ret;

	read_lock_bh(&priv->lock);
	seq = read_seqcount_begin(&priv->count);
	ret = __nft_rbtree_lookup(net, set, key, ext, seq);
	read_unlock_bh(&priv->lock);

	return ret;
}

static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
			       struct nft_rbtree_elem *new,
			       struct nft_set_ext **ext)
{
	struct nft_rbtree *priv = nft_set_priv(set);
	u8 genmask = nft_genmask_next(net);
	struct nft_rbtree_elem *rbe;
	struct rb_node *parent, **p;
	int d;

	parent = NULL;
	p = &priv->root.rb_node;
	while (*p != NULL) {
		parent = *p;
		rbe = rb_entry(parent, struct nft_rbtree_elem, node);
		d = memcmp(nft_set_ext_key(&rbe->ext),
			   nft_set_ext_key(&new->ext),
			   set->klen);
		if (d < 0)
			p = &parent->rb_left;
		else if (d > 0)
			p = &parent->rb_right;
		else {
			if (nft_rbtree_interval_end(rbe) &&
			    !nft_rbtree_interval_end(new)) {
				p = &parent->rb_left;
			} else if (!nft_rbtree_interval_end(rbe) &&
				   nft_rbtree_interval_end(new)) {
				p = &parent->rb_right;
			} else if (nft_set_elem_active(&rbe->ext, genmask)) {
				*ext = &rbe->ext;
				return -EEXIST;
			} else {
				p = &parent->rb_left;
			}
		}
	}
	rb_link_node_rcu(&new->node, parent, p);
	rb_insert_color(&new->node, &priv->root);
	return 0;
}

static int nft_rbtree_insert(const struct net *net, const struct nft_set *set,
			     const struct nft_set_elem *elem,
			     struct nft_set_ext **ext)
{
	struct nft_rbtree *priv = nft_set_priv(set);
	struct nft_rbtree_elem *rbe = elem->priv;
	int err;

	write_lock_bh(&priv->lock);
	write_seqcount_begin(&priv->count);
	err = __nft_rbtree_insert(net, set, rbe, ext);
	write_seqcount_end(&priv->count);
	write_unlock_bh(&priv->lock);

	return err;
}

static void nft_rbtree_remove(const struct net *net,
			      const struct nft_set *set,
			      const struct nft_set_elem *elem)
{
	struct nft_rbtree *priv = nft_set_priv(set);
	struct nft_rbtree_elem *rbe = elem->priv;

	write_lock_bh(&priv->lock);
	write_seqcount_begin(&priv->count);
	rb_erase(&rbe->node, &priv->root);
	write_seqcount_end(&priv->count);
	write_unlock_bh(&priv->lock);
}

static void nft_rbtree_activate(const struct net *net,
				const struct nft_set *set,
				const struct nft_set_elem *elem)
{
	struct nft_rbtree_elem *rbe = elem->priv;

	nft_set_elem_change_active(net, set, &rbe->ext);
}

static bool nft_rbtree_flush(const struct net *net,
			     const struct nft_set *set, void *priv)
{
	struct nft_rbtree_elem *rbe = priv;

	nft_set_elem_change_active(net, set, &rbe->ext);
	return true;
}

static void *nft_rbtree_deactivate(const struct net *net,
				   const struct nft_set *set,
				   const struct nft_set_elem *elem)
{
	const struct nft_rbtree *priv = nft_set_priv(set);
	const struct rb_node *parent = priv->root.rb_node;
	struct nft_rbtree_elem *rbe, *this = elem->priv;
	u8 genmask = nft_genmask_next(net);
	int d;

	while (parent != NULL) {
		rbe = rb_entry(parent, struct nft_rbtree_elem, node);

		d = memcmp(nft_set_ext_key(&rbe->ext), &elem->key.val,
					   set->klen);
		if (d < 0)
			parent = parent->rb_left;
		else if (d > 0)
			parent = parent->rb_right;
		else {
			if (!nft_set_elem_active(&rbe->ext, genmask)) {
				parent = parent->rb_left;
				continue;
			}
			if (nft_rbtree_interval_end(rbe) &&
			    !nft_rbtree_interval_end(this)) {
				parent = parent->rb_left;
				continue;
			} else if (!nft_rbtree_interval_end(rbe) &&
				   nft_rbtree_interval_end(this)) {
				parent = parent->rb_right;
				continue;
			}
			nft_rbtree_flush(net, set, rbe);
			return rbe;
		}
	}
	return NULL;
}

static void nft_rbtree_walk(const struct nft_ctx *ctx,
			    struct nft_set *set,
			    struct nft_set_iter *iter)
{
	struct nft_rbtree *priv = nft_set_priv(set);
	struct nft_rbtree_elem *rbe;
	struct nft_set_elem elem;
	struct rb_node *node;

	read_lock_bh(&priv->lock);
	for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) {
		rbe = rb_entry(node, struct nft_rbtree_elem, node);

		if (iter->count < iter->skip)
			goto cont;
		if (!nft_set_elem_active(&rbe->ext, iter->genmask))
			goto cont;

		elem.priv = rbe;

		iter->err = iter->fn(ctx, set, iter, &elem);
		if (iter->err < 0) {
			read_unlock_bh(&priv->lock);
			return;
		}
cont:
		iter->count++;
	}
	read_unlock_bh(&priv->lock);
}

static unsigned int nft_rbtree_privsize(const struct nlattr * const nla[],
					const struct nft_set_desc *desc)
{
	return sizeof(struct nft_rbtree);
}

static int nft_rbtree_init(const struct nft_set *set,
			   const struct nft_set_desc *desc,
			   const struct nlattr * const nla[])
{
	struct nft_rbtree *priv = nft_set_priv(set);

	rwlock_init(&priv->lock);
	seqcount_init(&priv->count);
	priv->root = RB_ROOT;
	return 0;
}

static void nft_rbtree_destroy(const struct nft_set *set)
{
	struct nft_rbtree *priv = nft_set_priv(set);
	struct nft_rbtree_elem *rbe;
	struct rb_node *node;

	while ((node = priv->root.rb_node) != NULL) {
		rb_erase(node, &priv->root);
		rbe = rb_entry(node, struct nft_rbtree_elem, node);
		nft_set_elem_destroy(set, rbe, true);
	}
}

static bool nft_rbtree_estimate(const struct nft_set_desc *desc, u32 features,
				struct nft_set_estimate *est)
{
	if (desc->size)
		est->size = sizeof(struct nft_rbtree) +
			    desc->size * sizeof(struct nft_rbtree_elem);
	else
		est->size = ~0;

	est->lookup = NFT_SET_CLASS_O_LOG_N;
	est->space  = NFT_SET_CLASS_O_N;

	return true;
}

static struct nft_set_type nft_rbtree_type;
static struct nft_set_ops nft_rbtree_ops __read_mostly = {
	.type		= &nft_rbtree_type,
	.privsize	= nft_rbtree_privsize,
	.elemsize	= offsetof(struct nft_rbtree_elem, ext),
	.estimate	= nft_rbtree_estimate,
	.init		= nft_rbtree_init,
	.destroy	= nft_rbtree_destroy,
	.insert		= nft_rbtree_insert,
	.remove		= nft_rbtree_remove,
	.deactivate	= nft_rbtree_deactivate,
	.flush		= nft_rbtree_flush,
	.activate	= nft_rbtree_activate,
	.lookup		= nft_rbtree_lookup,
	.walk		= nft_rbtree_walk,
	.features	= NFT_SET_INTERVAL | NFT_SET_MAP | NFT_SET_OBJECT,
};

static struct nft_set_type nft_rbtree_type __read_mostly = {
	.ops		= &nft_rbtree_ops,
	.owner		= THIS_MODULE,
};

static int __init nft_rbtree_module_init(void)
{
	return nft_register_set(&nft_rbtree_type);
}

static void __exit nft_rbtree_module_exit(void)
{
	nft_unregister_set(&nft_rbtree_type);
}

module_init(nft_rbtree_module_init);
module_exit(nft_rbtree_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_ALIAS_NFT_SET();