/*
   * 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 const struct tcf_ext_map route_ext_map = {

  	.police = TCA_ROUTE4_POLICE,
  	.action = TCA_ROUTE4_ACT
  };

  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 = (struct route4_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 = ((struct rtable *)dst)->rt_iif;

  
  	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 = (struct route4_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 = (struct route4_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 tcf_proto *tp, unsigned long base,
  	struct route4_filter *f, u32 handle, struct route4_head *head,

  	struct nlattr **tb, struct nlattr *est, int new)

  {
  	int err;
  	u32 id = 0, to = 0, nhandle = 0x8000;
  	struct route4_filter *fp;
  	unsigned int h1;
  	struct route4_bucket *b;
  	struct tcf_exts e;
  
  	err = tcf_exts_validate(tp, tb, est, &e, &route_ext_map);
  	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 tcf_proto *tp, unsigned long base,
  		       u32 handle,

  		       struct nlattr **tca,

  		       unsigned long *arg)
  {
  	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(tp, base, f, handle, head, tb,

  			tca[TCA_RATE], 0);

  		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;

  
  	err = route4_set_parms(tp, base, f, handle, head, tb,

  		tca[TCA_RATE], 1);

  	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 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;

  		NLA_PUT_U32(skb, TCA_ROUTE4_TO, id);

  	}

  	if (f->handle & 0x80000000) {
  		if ((f->handle >> 16) != 0xFFFF)

  			NLA_PUT_U32(skb, TCA_ROUTE4_IIF, f->iif);

  	} else {

  		id = f->id >> 16;

  		NLA_PUT_U32(skb, TCA_ROUTE4_FROM, id);

  	}
  	if (f->res.classid)

  		NLA_PUT_U32(skb, TCA_ROUTE4_CLASSID, f->res.classid);

  
  	if (tcf_exts_dump(skb, &f->exts, &route_ext_map) < 0)

  		goto nla_put_failure;

  	nla_nest_end(skb, nest);

  
  	if (tcf_exts_dump_stats(skb, &f->exts, &route_ext_map) < 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");