/*
 * net/sched/cls_route.c	ROUTE4 classifier.
 *
 *		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.
 *
 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/dst.h>
#include <net/route.h>
#include <net/netlink.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>

/*
 * 1. For now we assume that route tags < 256.
 *    It allows to use direct table lookups, instead of hash tables.
 * 2. For now we assume that "from TAG" and "fromdev DEV" statements
 *    are mutually  exclusive.
 * 3. "to TAG from ANY" has higher priority, than "to ANY from XXX"
 */

struct route4_fastmap {
	struct route4_filter	*filter;
	u32			id;
	int			iif;
};

struct route4_head {
	struct route4_fastmap	fastmap[16];
	struct route4_bucket	*table[256 + 1];
};

struct route4_bucket {
	/* 16 FROM buckets + 16 IIF buckets + 1 wildcard bucket */
	struct route4_filter	*ht[16 + 16 + 1];
};

struct route4_filter {
	struct route4_filter	*next;
	u32			id;
	int			iif;

	struct tcf_result	res;
	struct tcf_exts		exts;
	u32			handle;
	struct route4_bucket	*bkt;
};

#define ROUTE4_FAILURE ((struct route4_filter *)(-1L))

static inline int route4_fastmap_hash(u32 id, int iif)
{
	return id & 0xF;
}

static void
route4_reset_fastmap(struct Qdisc *q, struct route4_head *head, u32 id)
{
	spinlock_t *root_lock = qdisc_root_sleeping_lock(q);

	spin_lock_bh(root_lock);
	memset(head->fastmap, 0, sizeof(head->fastmap));
	spin_unlock_bh(root_lock);
}

static void
route4_set_fastmap(struct route4_head *head, u32 id, int iif,
		   struct route4_filter *f)
{
	int h = route4_fastmap_hash(id, iif);

	head->fastmap[h].id = id;
	head->fastmap[h].iif = iif;
	head->fastmap[h].filter = f;
}

static inline int route4_hash_to(u32 id)
{
	return id & 0xFF;
}

static inline int route4_hash_from(u32 id)
{
	return (id >> 16) & 0xF;
}

static inline int route4_hash_iif(int iif)
{
	return 16 + ((iif >> 16) & 0xF);
}

static inline int route4_hash_wild(void)
{
	return 32;
}

#define ROUTE4_APPLY_RESULT()					\
{								\
	*res = f->res;						\
	if (tcf_exts_is_available(&f->exts)) {			\
		int r = tcf_exts_exec(skb, &f->exts, res);	\
		if (r < 0) {					\
			dont_cache = 1;				\
			continue;				\
		}						\
		return r;					\
	} else if (!dont_cache)					\
		route4_set_fastmap(head, id, iif, f);		\
	return 0;						\
}

static int route4_classify(struct sk_buff *skb, const struct tcf_proto *tp,
			   struct tcf_result *res)
{
	struct route4_head *head = tp->root;
	struct dst_entry *dst;
	struct route4_bucket *b;
	struct route4_filter *f;
	u32 id, h;
	int iif, dont_cache = 0;

	dst = skb_dst(skb);
	if (!dst)
		goto failure;

	id = dst->tclassid;
	if (head == NULL)
		goto old_method;

	iif = inet_iif(skb);

	h = route4_fastmap_hash(id, iif);
	if (id == head->fastmap[h].id &&
	    iif == head->fastmap[h].iif &&
	    (f = head->fastmap[h].filter) != NULL) {
		if (f == ROUTE4_FAILURE)
			goto failure;

		*res = f->res;
		return 0;
	}

	h = route4_hash_to(id);

restart:
	b = head->table[h];
	if (b) {
		for (f = b->ht[route4_hash_from(id)]; f; f = f->next)
			if (f->id == id)
				ROUTE4_APPLY_RESULT();

		for (f = b->ht[route4_hash_iif(iif)]; f; f = f->next)
			if (f->iif == iif)
				ROUTE4_APPLY_RESULT();

		for (f = b->ht[route4_hash_wild()]; f; f = f->next)
			ROUTE4_APPLY_RESULT();

	}
	if (h < 256) {
		h = 256;
		id &= ~0xFFFF;
		goto restart;
	}

	if (!dont_cache)
		route4_set_fastmap(head, id, iif, ROUTE4_FAILURE);
failure:
	return -1;

old_method:
	if (id && (TC_H_MAJ(id) == 0 ||
		   !(TC_H_MAJ(id^tp->q->handle)))) {
		res->classid = id;
		res->class = 0;
		return 0;
	}
	return -1;
}

static inline u32 to_hash(u32 id)
{
	u32 h = id & 0xFF;

	if (id & 0x8000)
		h += 256;
	return h;
}

static inline u32 from_hash(u32 id)
{
	id &= 0xFFFF;
	if (id == 0xFFFF)
		return 32;
	if (!(id & 0x8000)) {
		if (id > 255)
			return 256;
		return id & 0xF;
	}
	return 16 + (id & 0xF);
}

static unsigned long route4_get(struct tcf_proto *tp, u32 handle)
{
	struct route4_head *head = tp->root;
	struct route4_bucket *b;
	struct route4_filter *f;
	unsigned int h1, h2;

	if (!head)
		return 0;

	h1 = to_hash(handle);
	if (h1 > 256)
		return 0;

	h2 = from_hash(handle >> 16);
	if (h2 > 32)
		return 0;

	b = head->table[h1];
	if (b) {
		for (f = b->ht[h2]; f; f = f->next)
			if (f->handle == handle)
				return (unsigned long)f;
	}
	return 0;
}

static void route4_put(struct tcf_proto *tp, unsigned long f)
{
}

static int route4_init(struct tcf_proto *tp)
{
	return 0;
}

static void
route4_delete_filter(struct tcf_proto *tp, struct route4_filter *f)
{
	tcf_unbind_filter(tp, &f->res);
	tcf_exts_destroy(tp, &f->exts);
	kfree(f);
}

static void route4_destroy(struct tcf_proto *tp)
{
	struct route4_head *head = tp->root;
	int h1, h2;

	if (head == NULL)
		return;

	for (h1 = 0; h1 <= 256; h1++) {
		struct route4_bucket *b;

		b = head->table[h1];
		if (b) {
			for (h2 = 0; h2 <= 32; h2++) {
				struct route4_filter *f;

				while ((f = b->ht[h2]) != NULL) {
					b->ht[h2] = f->next;
					route4_delete_filter(tp, f);
				}
			}
			kfree(b);
		}
	}
	kfree(head);
}

static int route4_delete(struct tcf_proto *tp, unsigned long arg)
{
	struct route4_head *head = tp->root;
	struct route4_filter **fp, *f = (struct route4_filter *)arg;
	unsigned int h = 0;
	struct route4_bucket *b;
	int i;

	if (!head || !f)
		return -EINVAL;

	h = f->handle;
	b = f->bkt;

	for (fp = &b->ht[from_hash(h >> 16)]; *fp; fp = &(*fp)->next) {
		if (*fp == f) {
			tcf_tree_lock(tp);
			*fp = f->next;
			tcf_tree_unlock(tp);

			route4_reset_fastmap(tp->q, head, f->id);
			route4_delete_filter(tp, f);

			/* Strip tree */

			for (i = 0; i <= 32; i++)
				if (b->ht[i])
					return 0;

			/* OK, session has no flows */
			tcf_tree_lock(tp);
			head->table[to_hash(h)] = NULL;
			tcf_tree_unlock(tp);

			kfree(b);
			return 0;
		}
	}
	return 0;
}

static const struct nla_policy route4_policy[TCA_ROUTE4_MAX + 1] = {
	[TCA_ROUTE4_CLASSID]	= { .type = NLA_U32 },
	[TCA_ROUTE4_TO]		= { .type = NLA_U32 },
	[TCA_ROUTE4_FROM]	= { .type = NLA_U32 },
	[TCA_ROUTE4_IIF]	= { .type = NLA_U32 },
};

static int route4_set_parms(struct net *net, struct tcf_proto *tp,
			    unsigned long base, struct route4_filter *f,
			    u32 handle, struct route4_head *head,
			    struct nlattr **tb, struct nlattr *est, int new,
			    bool ovr)
{
	int err;
	u32 id = 0, to = 0, nhandle = 0x8000;
	struct route4_filter *fp;
	unsigned int h1;
	struct route4_bucket *b;
	struct tcf_exts e;

	tcf_exts_init(&e, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE);
	err = tcf_exts_validate(net, tp, tb, est, &e, ovr);
	if (err < 0)
		return err;

	err = -EINVAL;
	if (tb[TCA_ROUTE4_TO]) {
		if (new && handle & 0x8000)
			goto errout;
		to = nla_get_u32(tb[TCA_ROUTE4_TO]);
		if (to > 0xFF)
			goto errout;
		nhandle = to;
	}

	if (tb[TCA_ROUTE4_FROM]) {
		if (tb[TCA_ROUTE4_IIF])
			goto errout;
		id = nla_get_u32(tb[TCA_ROUTE4_FROM]);
		if (id > 0xFF)
			goto errout;
		nhandle |= id << 16;
	} else if (tb[TCA_ROUTE4_IIF]) {
		id = nla_get_u32(tb[TCA_ROUTE4_IIF]);
		if (id > 0x7FFF)
			goto errout;
		nhandle |= (id | 0x8000) << 16;
	} else
		nhandle |= 0xFFFF << 16;

	if (handle && new) {
		nhandle |= handle & 0x7F00;
		if (nhandle != handle)
			goto errout;
	}

	h1 = to_hash(nhandle);
	b = head->table[h1];
	if (!b) {
		err = -ENOBUFS;
		b = kzalloc(sizeof(struct route4_bucket), GFP_KERNEL);
		if (b == NULL)
			goto errout;

		tcf_tree_lock(tp);
		head->table[h1] = b;
		tcf_tree_unlock(tp);
	} else {
		unsigned int h2 = from_hash(nhandle >> 16);

		err = -EEXIST;
		for (fp = b->ht[h2]; fp; fp = fp->next)
			if (fp->handle == f->handle)
				goto errout;
	}

	tcf_tree_lock(tp);
	if (tb[TCA_ROUTE4_TO])
		f->id = to;

	if (tb[TCA_ROUTE4_FROM])
		f->id = to | id<<16;
	else if (tb[TCA_ROUTE4_IIF])
		f->iif = id;

	f->handle = nhandle;
	f->bkt = b;
	tcf_tree_unlock(tp);

	if (tb[TCA_ROUTE4_CLASSID]) {
		f->res.classid = nla_get_u32(tb[TCA_ROUTE4_CLASSID]);
		tcf_bind_filter(tp, &f->res, base);
	}

	tcf_exts_change(tp, &f->exts, &e);

	return 0;
errout:
	tcf_exts_destroy(tp, &e);
	return err;
}

static int route4_change(struct net *net, struct sk_buff *in_skb,
		       struct tcf_proto *tp, unsigned long base,
		       u32 handle,
		       struct nlattr **tca,
		       unsigned long *arg, bool ovr)
{
	struct route4_head *head = tp->root;
	struct route4_filter *f, *f1, **fp;
	struct route4_bucket *b;
	struct nlattr *opt = tca[TCA_OPTIONS];
	struct nlattr *tb[TCA_ROUTE4_MAX + 1];
	unsigned int h, th;
	u32 old_handle = 0;
	int err;

	if (opt == NULL)
		return handle ? -EINVAL : 0;

	err = nla_parse_nested(tb, TCA_ROUTE4_MAX, opt, route4_policy);
	if (err < 0)
		return err;

	f = (struct route4_filter *)*arg;
	if (f) {
		if (f->handle != handle && handle)
			return -EINVAL;

		if (f->bkt)
			old_handle = f->handle;

		err = route4_set_parms(net, tp, base, f, handle, head, tb,
			tca[TCA_RATE], 0, ovr);
		if (err < 0)
			return err;

		goto reinsert;
	}

	err = -ENOBUFS;
	if (head == NULL) {
		head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
		if (head == NULL)
			goto errout;

		tcf_tree_lock(tp);
		tp->root = head;
		tcf_tree_unlock(tp);
	}

	f = kzalloc(sizeof(struct route4_filter), GFP_KERNEL);
	if (f == NULL)
		goto errout;

	tcf_exts_init(&f->exts, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE);
	err = route4_set_parms(net, tp, base, f, handle, head, tb,
		tca[TCA_RATE], 1, ovr);
	if (err < 0)
		goto errout;

reinsert:
	h = from_hash(f->handle >> 16);
	for (fp = &f->bkt->ht[h]; (f1 = *fp) != NULL; fp = &f1->next)
		if (f->handle < f1->handle)
			break;

	f->next = f1;
	tcf_tree_lock(tp);
	*fp = f;

	if (old_handle && f->handle != old_handle) {
		th = to_hash(old_handle);
		h = from_hash(old_handle >> 16);
		b = head->table[th];
		if (b) {
			for (fp = &b->ht[h]; *fp; fp = &(*fp)->next) {
				if (*fp == f) {
					*fp = f->next;
					break;
				}
			}
		}
	}
	tcf_tree_unlock(tp);

	route4_reset_fastmap(tp->q, head, f->id);
	*arg = (unsigned long)f;
	return 0;

errout:
	kfree(f);
	return err;
}

static void route4_walk(struct tcf_proto *tp, struct tcf_walker *arg)
{
	struct route4_head *head = tp->root;
	unsigned int h, h1;

	if (head == NULL)
		arg->stop = 1;

	if (arg->stop)
		return;

	for (h = 0; h <= 256; h++) {
		struct route4_bucket *b = head->table[h];

		if (b) {
			for (h1 = 0; h1 <= 32; h1++) {
				struct route4_filter *f;

				for (f = b->ht[h1]; f; f = f->next) {
					if (arg->count < arg->skip) {
						arg->count++;
						continue;
					}
					if (arg->fn(tp, (unsigned long)f, arg) < 0) {
						arg->stop = 1;
						return;
					}
					arg->count++;
				}
			}
		}
	}
}

static int route4_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
		       struct sk_buff *skb, struct tcmsg *t)
{
	struct route4_filter *f = (struct route4_filter *)fh;
	unsigned char *b = skb_tail_pointer(skb);
	struct nlattr *nest;
	u32 id;

	if (f == NULL)
		return skb->len;

	t->tcm_handle = f->handle;

	nest = nla_nest_start(skb, TCA_OPTIONS);
	if (nest == NULL)
		goto nla_put_failure;

	if (!(f->handle & 0x8000)) {
		id = f->id & 0xFF;
		if (nla_put_u32(skb, TCA_ROUTE4_TO, id))
			goto nla_put_failure;
	}
	if (f->handle & 0x80000000) {
		if ((f->handle >> 16) != 0xFFFF &&
		    nla_put_u32(skb, TCA_ROUTE4_IIF, f->iif))
			goto nla_put_failure;
	} else {
		id = f->id >> 16;
		if (nla_put_u32(skb, TCA_ROUTE4_FROM, id))
			goto nla_put_failure;
	}
	if (f->res.classid &&
	    nla_put_u32(skb, TCA_ROUTE4_CLASSID, f->res.classid))
		goto nla_put_failure;

	if (tcf_exts_dump(skb, &f->exts) < 0)
		goto nla_put_failure;

	nla_nest_end(skb, nest);

	if (tcf_exts_dump_stats(skb, &f->exts) < 0)
		goto nla_put_failure;

	return skb->len;

nla_put_failure:
	nlmsg_trim(skb, b);
	return -1;
}

static struct tcf_proto_ops cls_route4_ops __read_mostly = {
	.kind		=	"route",
	.classify	=	route4_classify,
	.init		=	route4_init,
	.destroy	=	route4_destroy,
	.get		=	route4_get,
	.put		=	route4_put,
	.change		=	route4_change,
	.delete		=	route4_delete,
	.walk		=	route4_walk,
	.dump		=	route4_dump,
	.owner		=	THIS_MODULE,
};

static int __init init_route4(void)
{
	return register_tcf_proto_ops(&cls_route4_ops);
}

static void __exit exit_route4(void)
{
	unregister_tcf_proto_ops(&cls_route4_ops);
}

module_init(init_route4)
module_exit(exit_route4)
MODULE_LICENSE("GPL");