/*

   *	Linux INET6 implementation

   *	Forwarding Information Database
   *
   *	Authors:

   *	Pedro Roque		<roque@di.fc.ul.pt>

   *
   *	$Id: ip6_fib.c,v 1.25 2001/10/31 21:55:55 davem Exp $
   *
   *	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.
   */
  
  /*
   * 	Changes:
   * 	Yuji SEKIYA @USAGI:	Support default route on router node;
   * 				remove ip6_null_entry from the top of
   * 				routing table.

   * 	Ville Nuorvala:		Fixed routing subtrees.

   */

  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/net.h>
  #include <linux/route.h>
  #include <linux/netdevice.h>
  #include <linux/in6.h>
  #include <linux/init.h>

  #include <linux/list.h>

  
  #ifdef 	CONFIG_PROC_FS
  #include <linux/proc_fs.h>
  #endif
  
  #include <net/ipv6.h>
  #include <net/ndisc.h>
  #include <net/addrconf.h>
  
  #include <net/ip6_fib.h>
  #include <net/ip6_route.h>
  
  #define RT6_DEBUG 2
  
  #if RT6_DEBUG >= 3
  #define RT6_TRACE(x...) printk(KERN_DEBUG x)
  #else
  #define RT6_TRACE(x...) do { ; } while (0)
  #endif

  static struct kmem_cache * fib6_node_kmem __read_mostly;

  
  enum fib_walk_state_t
  {
  #ifdef CONFIG_IPV6_SUBTREES
  	FWS_S,
  #endif
  	FWS_L,
  	FWS_R,
  	FWS_C,
  	FWS_U
  };
  
  struct fib6_cleaner_t
  {
  	struct fib6_walker_t w;

  	struct net *net;

  	int (*func)(struct rt6_info *, void *arg);
  	void *arg;
  };

  static DEFINE_RWLOCK(fib6_walker_lock);

  
  #ifdef CONFIG_IPV6_SUBTREES
  #define FWS_INIT FWS_S

  #else
  #define FWS_INIT FWS_L

  #endif

  static void fib6_prune_clones(struct net *net, struct fib6_node *fn,
  			      struct rt6_info *rt);

  static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
  static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);

  static int fib6_walk(struct fib6_walker_t *w);
  static int fib6_walk_continue(struct fib6_walker_t *w);

  
  /*
   *	A routing update causes an increase of the serial number on the
   *	affected subtree. This allows for cached routes to be asynchronously
   *	tested when modifications are made to the destination cache as a
   *	result of redirects, path MTU changes, etc.
   */
  
  static __u32 rt_sernum;

  static void fib6_gc_timer_cb(unsigned long arg);

  static struct fib6_walker_t fib6_walker_list = {

  	.prev	= &fib6_walker_list,

  	.next	= &fib6_walker_list,

  };
  
  #define FOR_WALKERS(w) for ((w)=fib6_walker_list.next; (w) != &fib6_walker_list; (w)=(w)->next)

  static inline void fib6_walker_link(struct fib6_walker_t *w)
  {
  	write_lock_bh(&fib6_walker_lock);
  	w->next = fib6_walker_list.next;
  	w->prev = &fib6_walker_list;
  	w->next->prev = w;
  	w->prev->next = w;
  	write_unlock_bh(&fib6_walker_lock);
  }
  
  static inline void fib6_walker_unlink(struct fib6_walker_t *w)
  {
  	write_lock_bh(&fib6_walker_lock);
  	w->next->prev = w->prev;
  	w->prev->next = w->next;
  	w->prev = w->next = w;
  	write_unlock_bh(&fib6_walker_lock);
  }

  static __inline__ u32 fib6_new_sernum(void)
  {
  	u32 n = ++rt_sernum;
  	if ((__s32)n <= 0)
  		rt_sernum = n = 1;
  	return n;
  }
  
  /*
   *	Auxiliary address test functions for the radix tree.
   *

   *	These assume a 32bit processor (although it will work on

   *	64bit processors)
   */
  
  /*
   *	test bit
   */

  static __inline__ __be32 addr_bit_set(void *token, int fn_bit)

  {

  	__be32 *addr = token;

  
  	return htonl(1 << ((~fn_bit)&0x1F)) & addr[fn_bit>>5];
  }

  static __inline__ struct fib6_node * node_alloc(void)
  {
  	struct fib6_node *fn;

  	fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);

  
  	return fn;
  }
  
  static __inline__ void node_free(struct fib6_node * fn)
  {
  	kmem_cache_free(fib6_node_kmem, fn);
  }
  
  static __inline__ void rt6_release(struct rt6_info *rt)
  {
  	if (atomic_dec_and_test(&rt->rt6i_ref))
  		dst_free(&rt->u.dst);
  }

  #ifdef CONFIG_IPV6_MULTIPLE_TABLES

  #define FIB_TABLE_HASHSZ 256
  #else
  #define FIB_TABLE_HASHSZ 1
  #endif

  static void fib6_link_table(struct net *net, struct fib6_table *tb)

  {
  	unsigned int h;

  	/*
  	 * Initialize table lock at a single place to give lockdep a key,
  	 * tables aren't visible prior to being linked to the list.
  	 */
  	rwlock_init(&tb->tb6_lock);

  	h = tb->tb6_id & (FIB_TABLE_HASHSZ - 1);
  
  	/*
  	 * No protection necessary, this is the only list mutatation
  	 * operation, tables never disappear once they exist.
  	 */

  	hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);

  }

  #ifdef CONFIG_IPV6_MULTIPLE_TABLES

  static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)

  {
  	struct fib6_table *table;
  
  	table = kzalloc(sizeof(*table), GFP_ATOMIC);
  	if (table != NULL) {
  		table->tb6_id = id;

  		table->tb6_root.leaf = net->ipv6.ip6_null_entry;

  		table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
  	}
  
  	return table;
  }

  struct fib6_table *fib6_new_table(struct net *net, u32 id)

  {
  	struct fib6_table *tb;
  
  	if (id == 0)
  		id = RT6_TABLE_MAIN;

  	tb = fib6_get_table(net, id);

  	if (tb)
  		return tb;

  	tb = fib6_alloc_table(net, id);

  	if (tb != NULL)

  		fib6_link_table(net, tb);

  
  	return tb;
  }

  struct fib6_table *fib6_get_table(struct net *net, u32 id)

  {
  	struct fib6_table *tb;

  	struct hlist_head *head;

  	struct hlist_node *node;
  	unsigned int h;
  
  	if (id == 0)
  		id = RT6_TABLE_MAIN;
  	h = id & (FIB_TABLE_HASHSZ - 1);
  	rcu_read_lock();

  	head = &net->ipv6.fib_table_hash[h];
  	hlist_for_each_entry_rcu(tb, node, head, tb6_hlist) {

  		if (tb->tb6_id == id) {
  			rcu_read_unlock();
  			return tb;
  		}
  	}
  	rcu_read_unlock();
  
  	return NULL;
  }

  static void fib6_tables_init(struct net *net)

  {

  	fib6_link_table(net, net->ipv6.fib6_main_tbl);
  	fib6_link_table(net, net->ipv6.fib6_local_tbl);

  }

  #else

  struct fib6_table *fib6_new_table(struct net *net, u32 id)

  {

  	return fib6_get_table(net, id);

  }

  struct fib6_table *fib6_get_table(struct net *net, u32 id)

  {

  	  return net->ipv6.fib6_main_tbl;

  }

  struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi *fl,
  				   int flags, pol_lookup_t lookup)

  {

  	return (struct dst_entry *) lookup(net, net->ipv6.fib6_main_tbl, fl, flags);

  }

  static void fib6_tables_init(struct net *net)

  {

  	fib6_link_table(net, net->ipv6.fib6_main_tbl);

  }
  
  #endif

  static int fib6_dump_node(struct fib6_walker_t *w)
  {
  	int res;
  	struct rt6_info *rt;

  	for (rt = w->leaf; rt; rt = rt->u.dst.rt6_next) {

  		res = rt6_dump_route(rt, w->args);
  		if (res < 0) {
  			/* Frame is full, suspend walking */
  			w->leaf = rt;
  			return 1;
  		}
  		BUG_TRAP(res!=0);
  	}
  	w->leaf = NULL;
  	return 0;
  }
  
  static void fib6_dump_end(struct netlink_callback *cb)
  {
  	struct fib6_walker_t *w = (void*)cb->args[2];
  
  	if (w) {
  		cb->args[2] = 0;
  		kfree(w);
  	}
  	cb->done = (void*)cb->args[3];
  	cb->args[1] = 3;
  }
  
  static int fib6_dump_done(struct netlink_callback *cb)
  {
  	fib6_dump_end(cb);
  	return cb->done ? cb->done(cb) : 0;
  }
  
  static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
  			   struct netlink_callback *cb)
  {
  	struct fib6_walker_t *w;
  	int res;
  
  	w = (void *)cb->args[2];
  	w->root = &table->tb6_root;
  
  	if (cb->args[4] == 0) {
  		read_lock_bh(&table->tb6_lock);
  		res = fib6_walk(w);
  		read_unlock_bh(&table->tb6_lock);
  		if (res > 0)
  			cb->args[4] = 1;
  	} else {
  		read_lock_bh(&table->tb6_lock);
  		res = fib6_walk_continue(w);
  		read_unlock_bh(&table->tb6_lock);
  		if (res != 0) {
  			if (res < 0)
  				fib6_walker_unlink(w);
  			goto end;
  		}
  		fib6_walker_unlink(w);
  		cb->args[4] = 0;
  	}
  end:
  	return res;
  }

  static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)

  {

  	struct net *net = sock_net(skb->sk);

  	unsigned int h, s_h;
  	unsigned int e = 0, s_e;
  	struct rt6_rtnl_dump_arg arg;
  	struct fib6_walker_t *w;
  	struct fib6_table *tb;
  	struct hlist_node *node;

  	struct hlist_head *head;

  	int res = 0;
  
  	s_h = cb->args[0];
  	s_e = cb->args[1];
  
  	w = (void *)cb->args[2];
  	if (w == NULL) {
  		/* New dump:
  		 *
  		 * 1. hook callback destructor.
  		 */
  		cb->args[3] = (long)cb->done;
  		cb->done = fib6_dump_done;
  
  		/*
  		 * 2. allocate and initialize walker.
  		 */
  		w = kzalloc(sizeof(*w), GFP_ATOMIC);
  		if (w == NULL)
  			return -ENOMEM;
  		w->func = fib6_dump_node;
  		cb->args[2] = (long)w;
  	}
  
  	arg.skb = skb;
  	arg.cb = cb;
  	w->args = &arg;
  
  	for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
  		e = 0;

  		head = &net->ipv6.fib_table_hash[h];
  		hlist_for_each_entry(tb, node, head, tb6_hlist) {

  			if (e < s_e)
  				goto next;
  			res = fib6_dump_table(tb, skb, cb);
  			if (res != 0)
  				goto out;
  next:
  			e++;
  		}
  	}
  out:
  	cb->args[1] = e;
  	cb->args[0] = h;
  
  	res = res < 0 ? res : skb->len;
  	if (res <= 0)
  		fib6_dump_end(cb);
  	return res;
  }

  
  /*
   *	Routing Table
   *
   *	return the appropriate node for a routing tree "add" operation
   *	by either creating and inserting or by returning an existing
   *	node.
   */
  
  static struct fib6_node * fib6_add_1(struct fib6_node *root, void *addr,
  				     int addrlen, int plen,
  				     int offset)
  {
  	struct fib6_node *fn, *in, *ln;
  	struct fib6_node *pn = NULL;
  	struct rt6key *key;
  	int	bit;

  	__be32	dir = 0;

  	__u32	sernum = fib6_new_sernum();
  
  	RT6_TRACE("fib6_add_1
  ");
  
  	/* insert node in tree */
  
  	fn = root;
  
  	do {
  		key = (struct rt6key *)((u8 *)fn->leaf + offset);
  
  		/*
  		 *	Prefix match
  		 */
  		if (plen < fn->fn_bit ||
  		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
  			goto insert_above;

  		/*
  		 *	Exact match ?
  		 */

  		if (plen == fn->fn_bit) {
  			/* clean up an intermediate node */
  			if ((fn->fn_flags & RTN_RTINFO) == 0) {
  				rt6_release(fn->leaf);
  				fn->leaf = NULL;
  			}

  			fn->fn_sernum = sernum;

  			return fn;
  		}
  
  		/*
  		 *	We have more bits to go
  		 */

  		/* Try to walk down on tree. */
  		fn->fn_sernum = sernum;
  		dir = addr_bit_set(addr, fn->fn_bit);
  		pn = fn;
  		fn = dir ? fn->right: fn->left;
  	} while (fn);
  
  	/*
  	 *	We walked to the bottom of tree.
  	 *	Create new leaf node without children.
  	 */
  
  	ln = node_alloc();
  
  	if (ln == NULL)
  		return NULL;
  	ln->fn_bit = plen;

  	ln->parent = pn;
  	ln->fn_sernum = sernum;
  
  	if (dir)
  		pn->right = ln;
  	else
  		pn->left  = ln;
  
  	return ln;
  
  
  insert_above:
  	/*

  	 * split since we don't have a common prefix anymore or

  	 * we have a less significant route.
  	 * we've to insert an intermediate node on the list
  	 * this new node will point to the one we need to create
  	 * and the current
  	 */
  
  	pn = fn->parent;
  
  	/* find 1st bit in difference between the 2 addrs.

  	   See comment in __ipv6_addr_diff: bit may be an invalid value,

  	   but if it is >= plen, the value is ignored in any case.
  	 */

  	bit = __ipv6_addr_diff(addr, &key->addr, addrlen);

  	/*
  	 *		(intermediate)[in]

  	 *	          /	   \
  	 *	(new leaf node)[ln] (old node)[fn]
  	 */
  	if (plen > bit) {
  		in = node_alloc();
  		ln = node_alloc();

  		if (in == NULL || ln == NULL) {
  			if (in)
  				node_free(in);
  			if (ln)
  				node_free(ln);
  			return NULL;
  		}

  		/*
  		 * new intermediate node.

  		 * RTN_RTINFO will
  		 * be off since that an address that chooses one of
  		 * the branches would not match less specific routes
  		 * in the other branch
  		 */
  
  		in->fn_bit = bit;
  
  		in->parent = pn;
  		in->leaf = fn->leaf;
  		atomic_inc(&in->leaf->rt6i_ref);
  
  		in->fn_sernum = sernum;
  
  		/* update parent pointer */
  		if (dir)
  			pn->right = in;
  		else
  			pn->left  = in;
  
  		ln->fn_bit = plen;
  
  		ln->parent = in;
  		fn->parent = in;
  
  		ln->fn_sernum = sernum;
  
  		if (addr_bit_set(addr, bit)) {
  			in->right = ln;
  			in->left  = fn;
  		} else {
  			in->left  = ln;
  			in->right = fn;
  		}
  	} else { /* plen <= bit */

  		/*

  		 *		(new leaf node)[ln]
  		 *	          /	   \
  		 *	     (old node)[fn] NULL
  		 */
  
  		ln = node_alloc();
  
  		if (ln == NULL)
  			return NULL;
  
  		ln->fn_bit = plen;
  
  		ln->parent = pn;
  
  		ln->fn_sernum = sernum;

  		if (dir)
  			pn->right = ln;
  		else
  			pn->left  = ln;
  
  		if (addr_bit_set(&key->addr, plen))
  			ln->right = fn;
  		else
  			ln->left  = fn;
  
  		fn->parent = ln;
  	}
  	return ln;
  }
  
  /*
   *	Insert routing information in a node.
   */
  
  static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,

  			    struct nl_info *info)

  {
  	struct rt6_info *iter = NULL;
  	struct rt6_info **ins;
  
  	ins = &fn->leaf;

  	for (iter = fn->leaf; iter; iter=iter->u.dst.rt6_next) {

  		/*
  		 *	Search for duplicates
  		 */
  
  		if (iter->rt6i_metric == rt->rt6i_metric) {
  			/*
  			 *	Same priority level
  			 */
  
  			if (iter->rt6i_dev == rt->rt6i_dev &&
  			    iter->rt6i_idev == rt->rt6i_idev &&
  			    ipv6_addr_equal(&iter->rt6i_gateway,
  					    &rt->rt6i_gateway)) {
  				if (!(iter->rt6i_flags&RTF_EXPIRES))
  					return -EEXIST;
  				iter->rt6i_expires = rt->rt6i_expires;
  				if (!(rt->rt6i_flags&RTF_EXPIRES)) {
  					iter->rt6i_flags &= ~RTF_EXPIRES;
  					iter->rt6i_expires = 0;
  				}
  				return -EEXIST;
  			}
  		}
  
  		if (iter->rt6i_metric > rt->rt6i_metric)
  			break;

  		ins = &iter->u.dst.rt6_next;

  	}

  	/* Reset round-robin state, if necessary */
  	if (ins == &fn->leaf)
  		fn->rr_ptr = NULL;

  	/*
  	 *	insert node
  	 */

  	rt->u.dst.rt6_next = iter;

  	*ins = rt;
  	rt->rt6i_node = fn;
  	atomic_inc(&rt->rt6i_ref);

  	inet6_rt_notify(RTM_NEWROUTE, rt, info);

  	info->nl_net->ipv6.rt6_stats->fib_rt_entries++;

  
  	if ((fn->fn_flags & RTN_RTINFO) == 0) {

  		info->nl_net->ipv6.rt6_stats->fib_route_nodes++;

  		fn->fn_flags |= RTN_RTINFO;
  	}
  
  	return 0;
  }

  static __inline__ void fib6_start_gc(struct net *net, struct rt6_info *rt)

  {

  	if (net->ipv6.ip6_fib_timer->expires == 0 &&

  	    (rt->rt6i_flags & (RTF_EXPIRES|RTF_CACHE)))

  		mod_timer(net->ipv6.ip6_fib_timer, jiffies +
  			  net->ipv6.sysctl.ip6_rt_gc_interval);

  }

  void fib6_force_start_gc(struct net *net)

  {

  	if (net->ipv6.ip6_fib_timer->expires == 0)
  		mod_timer(net->ipv6.ip6_fib_timer, jiffies +
  			  net->ipv6.sysctl.ip6_rt_gc_interval);

  }
  
  /*
   *	Add routing information to the routing tree.
   *	<destination addr>/<source addr>
   *	with source addr info in sub-trees
   */

  int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info)

  {

  	struct fib6_node *fn, *pn = NULL;

  	int err = -ENOMEM;
  
  	fn = fib6_add_1(root, &rt->rt6i_dst.addr, sizeof(struct in6_addr),
  			rt->rt6i_dst.plen, offsetof(struct rt6_info, rt6i_dst));
  
  	if (fn == NULL)
  		goto out;

  	pn = fn;

  #ifdef CONFIG_IPV6_SUBTREES
  	if (rt->rt6i_src.plen) {
  		struct fib6_node *sn;
  
  		if (fn->subtree == NULL) {
  			struct fib6_node *sfn;
  
  			/*
  			 * Create subtree.
  			 *
  			 *		fn[main tree]
  			 *		|
  			 *		sfn[subtree root]
  			 *		   \
  			 *		    sn[new leaf node]
  			 */
  
  			/* Create subtree root node */
  			sfn = node_alloc();
  			if (sfn == NULL)
  				goto st_failure;

  			sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
  			atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);

  			sfn->fn_flags = RTN_ROOT;
  			sfn->fn_sernum = fib6_new_sernum();
  
  			/* Now add the first leaf node to new subtree */
  
  			sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
  					sizeof(struct in6_addr), rt->rt6i_src.plen,
  					offsetof(struct rt6_info, rt6i_src));
  
  			if (sn == NULL) {
  				/* If it is failed, discard just allocated
  				   root, and then (in st_failure) stale node
  				   in main tree.
  				 */
  				node_free(sfn);
  				goto st_failure;
  			}
  
  			/* Now link new subtree to main tree */
  			sfn->parent = fn;
  			fn->subtree = sfn;

  		} else {
  			sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
  					sizeof(struct in6_addr), rt->rt6i_src.plen,
  					offsetof(struct rt6_info, rt6i_src));
  
  			if (sn == NULL)
  				goto st_failure;
  		}

  		if (fn->leaf == NULL) {
  			fn->leaf = rt;
  			atomic_inc(&rt->rt6i_ref);
  		}

  		fn = sn;
  	}
  #endif

  	err = fib6_add_rt2node(fn, rt, info);

  
  	if (err == 0) {

  		fib6_start_gc(info->nl_net, rt);

  		if (!(rt->rt6i_flags&RTF_CACHE))

  			fib6_prune_clones(info->nl_net, pn, rt);

  	}
  
  out:

  	if (err) {
  #ifdef CONFIG_IPV6_SUBTREES
  		/*
  		 * If fib6_add_1 has cleared the old leaf pointer in the
  		 * super-tree leaf node we have to find a new one for it.
  		 */

  		if (pn != fn && pn->leaf == rt) {
  			pn->leaf = NULL;
  			atomic_dec(&rt->rt6i_ref);
  		}

  		if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {

  			pn->leaf = fib6_find_prefix(info->nl_net, pn);

  #if RT6_DEBUG >= 2
  			if (!pn->leaf) {
  				BUG_TRAP(pn->leaf != NULL);

  				pn->leaf = info->nl_net->ipv6.ip6_null_entry;

  			}
  #endif
  			atomic_inc(&pn->leaf->rt6i_ref);
  		}
  #endif

  		dst_free(&rt->u.dst);

  	}

  	return err;
  
  #ifdef CONFIG_IPV6_SUBTREES
  	/* Subtree creation failed, probably main tree node
  	   is orphan. If it is, shoot it.
  	 */
  st_failure:
  	if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))

  		fib6_repair_tree(info->nl_net, fn);

  	dst_free(&rt->u.dst);
  	return err;
  #endif
  }
  
  /*
   *	Routing tree lookup
   *
   */
  
  struct lookup_args {
  	int		offset;		/* key offset on rt6_info	*/
  	struct in6_addr	*addr;		/* search key			*/
  };
  
  static struct fib6_node * fib6_lookup_1(struct fib6_node *root,
  					struct lookup_args *args)
  {
  	struct fib6_node *fn;

  	__be32 dir;

  	if (unlikely(args->offset == 0))
  		return NULL;

  	/*
  	 *	Descend on a tree
  	 */
  
  	fn = root;
  
  	for (;;) {
  		struct fib6_node *next;
  
  		dir = addr_bit_set(args->addr, fn->fn_bit);
  
  		next = dir ? fn->right : fn->left;
  
  		if (next) {
  			fn = next;
  			continue;
  		}
  
  		break;
  	}

  	while(fn) {

  		if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {

  			struct rt6key *key;
  
  			key = (struct rt6key *) ((u8 *) fn->leaf +
  						 args->offset);

  			if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
  #ifdef CONFIG_IPV6_SUBTREES
  				if (fn->subtree)
  					fn = fib6_lookup_1(fn->subtree, args + 1);
  #endif
  				if (!fn || fn->fn_flags & RTN_RTINFO)
  					return fn;
  			}

  		}

  		if (fn->fn_flags & RTN_ROOT)
  			break;

  		fn = fn->parent;
  	}
  
  	return NULL;
  }
  
  struct fib6_node * fib6_lookup(struct fib6_node *root, struct in6_addr *daddr,
  			       struct in6_addr *saddr)
  {

  	struct fib6_node *fn;

  	struct lookup_args args[] = {
  		{
  			.offset = offsetof(struct rt6_info, rt6i_dst),
  			.addr = daddr,
  		},

  #ifdef CONFIG_IPV6_SUBTREES

  		{
  			.offset = offsetof(struct rt6_info, rt6i_src),
  			.addr = saddr,
  		},

  #endif

  		{
  			.offset = 0,	/* sentinel */
  		}
  	};

  	fn = fib6_lookup_1(root, daddr ? args : args + 1);

  
  	if (fn == NULL || fn->fn_flags & RTN_TL_ROOT)
  		fn = root;
  
  	return fn;
  }
  
  /*
   *	Get node with specified destination prefix (and source prefix,
   *	if subtrees are used)
   */
  
  
  static struct fib6_node * fib6_locate_1(struct fib6_node *root,
  					struct in6_addr *addr,
  					int plen, int offset)
  {
  	struct fib6_node *fn;
  
  	for (fn = root; fn ; ) {
  		struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
  
  		/*
  		 *	Prefix match
  		 */
  		if (plen < fn->fn_bit ||
  		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
  			return NULL;
  
  		if (plen == fn->fn_bit)
  			return fn;
  
  		/*
  		 *	We have more bits to go
  		 */
  		if (addr_bit_set(addr, fn->fn_bit))
  			fn = fn->right;
  		else
  			fn = fn->left;
  	}
  	return NULL;
  }
  
  struct fib6_node * fib6_locate(struct fib6_node *root,
  			       struct in6_addr *daddr, int dst_len,
  			       struct in6_addr *saddr, int src_len)
  {
  	struct fib6_node *fn;
  
  	fn = fib6_locate_1(root, daddr, dst_len,
  			   offsetof(struct rt6_info, rt6i_dst));
  
  #ifdef CONFIG_IPV6_SUBTREES
  	if (src_len) {
  		BUG_TRAP(saddr!=NULL);

  		if (fn && fn->subtree)
  			fn = fib6_locate_1(fn->subtree, saddr, src_len,

  					   offsetof(struct rt6_info, rt6i_src));
  	}
  #endif
  
  	if (fn && fn->fn_flags&RTN_RTINFO)
  		return fn;
  
  	return NULL;
  }
  
  
  /*
   *	Deletion
   *
   */

  static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)

  {
  	if (fn->fn_flags&RTN_ROOT)

  		return net->ipv6.ip6_null_entry;

  
  	while(fn) {
  		if(fn->left)
  			return fn->left->leaf;
  
  		if(fn->right)
  			return fn->right->leaf;

  		fn = FIB6_SUBTREE(fn);

  	}
  	return NULL;
  }
  
  /*
   *	Called to trim the tree of intermediate nodes when possible. "fn"
   *	is the node we want to try and remove.
   */

  static struct fib6_node *fib6_repair_tree(struct net *net,
  					   struct fib6_node *fn)

  {
  	int children;
  	int nstate;
  	struct fib6_node *child, *pn;
  	struct fib6_walker_t *w;
  	int iter = 0;
  
  	for (;;) {
  		RT6_TRACE("fixing tree: plen=%d iter=%d
  ", fn->fn_bit, iter);
  		iter++;
  
  		BUG_TRAP(!(fn->fn_flags&RTN_RTINFO));
  		BUG_TRAP(!(fn->fn_flags&RTN_TL_ROOT));
  		BUG_TRAP(fn->leaf==NULL);
  
  		children = 0;
  		child = NULL;
  		if (fn->right) child = fn->right, children |= 1;
  		if (fn->left) child = fn->left, children |= 2;

  		if (children == 3 || FIB6_SUBTREE(fn)

  #ifdef CONFIG_IPV6_SUBTREES
  		    /* Subtree root (i.e. fn) may have one child */
  		    || (children && fn->fn_flags&RTN_ROOT)
  #endif
  		    ) {

  			fn->leaf = fib6_find_prefix(net, fn);

  #if RT6_DEBUG >= 2
  			if (fn->leaf==NULL) {
  				BUG_TRAP(fn->leaf);

  				fn->leaf = net->ipv6.ip6_null_entry;

  			}
  #endif
  			atomic_inc(&fn->leaf->rt6i_ref);
  			return fn->parent;
  		}
  
  		pn = fn->parent;
  #ifdef CONFIG_IPV6_SUBTREES

  		if (FIB6_SUBTREE(pn) == fn) {

  			BUG_TRAP(fn->fn_flags&RTN_ROOT);

  			FIB6_SUBTREE(pn) = NULL;

  			nstate = FWS_L;
  		} else {
  			BUG_TRAP(!(fn->fn_flags&RTN_ROOT));
  #endif
  			if (pn->right == fn) pn->right = child;
  			else if (pn->left == fn) pn->left = child;
  #if RT6_DEBUG >= 2
  			else BUG_TRAP(0);
  #endif
  			if (child)
  				child->parent = pn;
  			nstate = FWS_R;
  #ifdef CONFIG_IPV6_SUBTREES
  		}
  #endif
  
  		read_lock(&fib6_walker_lock);
  		FOR_WALKERS(w) {
  			if (child == NULL) {
  				if (w->root == fn) {
  					w->root = w->node = NULL;
  					RT6_TRACE("W %p adjusted by delroot 1
  ", w);
  				} else if (w->node == fn) {
  					RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d
  ", w, w->state, nstate);
  					w->node = pn;
  					w->state = nstate;
  				}
  			} else {
  				if (w->root == fn) {
  					w->root = child;
  					RT6_TRACE("W %p adjusted by delroot 2
  ", w);
  				}
  				if (w->node == fn) {
  					w->node = child;
  					if (children&2) {
  						RT6_TRACE("W %p adjusted by delnode 2, s=%d
  ", w, w->state);
  						w->state = w->state>=FWS_R ? FWS_U : FWS_INIT;
  					} else {
  						RT6_TRACE("W %p adjusted by delnode 2, s=%d
  ", w, w->state);
  						w->state = w->state>=FWS_C ? FWS_U : FWS_INIT;
  					}
  				}
  			}
  		}
  		read_unlock(&fib6_walker_lock);
  
  		node_free(fn);

  		if (pn->fn_flags&RTN_RTINFO || FIB6_SUBTREE(pn))

  			return pn;
  
  		rt6_release(pn->leaf);
  		pn->leaf = NULL;
  		fn = pn;
  	}
  }
  
  static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,

  			   struct nl_info *info)

  {
  	struct fib6_walker_t *w;
  	struct rt6_info *rt = *rtp;

  	struct net *net = info->nl_net;

  
  	RT6_TRACE("fib6_del_route
  ");
  
  	/* Unlink it */

  	*rtp = rt->u.dst.rt6_next;

  	rt->rt6i_node = NULL;

  	net->ipv6.rt6_stats->fib_rt_entries--;
  	net->ipv6.rt6_stats->fib_discarded_routes++;

  	/* Reset round-robin state, if necessary */
  	if (fn->rr_ptr == rt)
  		fn->rr_ptr = NULL;

  	/* Adjust walkers */
  	read_lock(&fib6_walker_lock);
  	FOR_WALKERS(w) {
  		if (w->state == FWS_C && w->leaf == rt) {
  			RT6_TRACE("walker %p adjusted by delroute
  ", w);

  			w->leaf = rt->u.dst.rt6_next;

  			if (w->leaf == NULL)
  				w->state = FWS_U;
  		}
  	}
  	read_unlock(&fib6_walker_lock);

  	rt->u.dst.rt6_next = NULL;

  	/* If it was last route, expunge its radix tree node */
  	if (fn->leaf == NULL) {
  		fn->fn_flags &= ~RTN_RTINFO;

  		net->ipv6.rt6_stats->fib_route_nodes--;

  		fn = fib6_repair_tree(net, fn);

  	}
  
  	if (atomic_read(&rt->rt6i_ref) != 1) {
  		/* This route is used as dummy address holder in some split
  		 * nodes. It is not leaked, but it still holds other resources,
  		 * which must be released in time. So, scan ascendant nodes
  		 * and replace dummy references to this route with references
  		 * to still alive ones.
  		 */
  		while (fn) {
  			if (!(fn->fn_flags&RTN_RTINFO) && fn->leaf == rt) {

  				fn->leaf = fib6_find_prefix(net, fn);

  				atomic_inc(&fn->leaf->rt6i_ref);
  				rt6_release(rt);
  			}
  			fn = fn->parent;
  		}
  		/* No more references are possible at this point. */

  		BUG_ON(atomic_read(&rt->rt6i_ref) != 1);

  	}

  	inet6_rt_notify(RTM_DELROUTE, rt, info);

  	rt6_release(rt);
  }

  int fib6_del(struct rt6_info *rt, struct nl_info *info)

  {

  	struct net *net = info->nl_net;

  	struct fib6_node *fn = rt->rt6i_node;
  	struct rt6_info **rtp;
  
  #if RT6_DEBUG >= 2
  	if (rt->u.dst.obsolete>0) {
  		BUG_TRAP(fn==NULL);
  		return -ENOENT;
  	}
  #endif

  	if (fn == NULL || rt == net->ipv6.ip6_null_entry)

  		return -ENOENT;
  
  	BUG_TRAP(fn->fn_flags&RTN_RTINFO);

  	if (!(rt->rt6i_flags&RTF_CACHE)) {
  		struct fib6_node *pn = fn;
  #ifdef CONFIG_IPV6_SUBTREES
  		/* clones of this route might be in another subtree */
  		if (rt->rt6i_src.plen) {
  			while (!(pn->fn_flags&RTN_ROOT))
  				pn = pn->parent;
  			pn = pn->parent;
  		}
  #endif

  		fib6_prune_clones(info->nl_net, pn, rt);

  	}

  
  	/*
  	 *	Walk the leaf entries looking for ourself
  	 */

  	for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->u.dst.rt6_next) {

  		if (*rtp == rt) {

  			fib6_del_route(fn, rtp, info);

  			return 0;
  		}
  	}
  	return -ENOENT;
  }
  
  /*
   *	Tree traversal function.
   *
   *	Certainly, it is not interrupt safe.
   *	However, it is internally reenterable wrt itself and fib6_add/fib6_del.
   *	It means, that we can modify tree during walking
   *	and use this function for garbage collection, clone pruning,

   *	cleaning tree when a device goes down etc. etc.

   *
   *	It guarantees that every node will be traversed,
   *	and that it will be traversed only once.
   *
   *	Callback function w->func may return:
   *	0 -> continue walking.
   *	positive value -> walking is suspended (used by tree dumps,
   *	and probably by gc, if it will be split to several slices)
   *	negative value -> terminate walking.
   *
   *	The function itself returns:
   *	0   -> walk is complete.
   *	>0  -> walk is incomplete (i.e. suspended)
   *	<0  -> walk is terminated by an error.
   */

  static int fib6_walk_continue(struct fib6_walker_t *w)

  {
  	struct fib6_node *fn, *pn;
  
  	for (;;) {
  		fn = w->node;
  		if (fn == NULL)
  			return 0;
  
  		if (w->prune && fn != w->root &&
  		    fn->fn_flags&RTN_RTINFO && w->state < FWS_C) {
  			w->state = FWS_C;
  			w->leaf = fn->leaf;
  		}
  		switch (w->state) {
  #ifdef CONFIG_IPV6_SUBTREES
  		case FWS_S:

  			if (FIB6_SUBTREE(fn)) {
  				w->node = FIB6_SUBTREE(fn);

  				continue;
  			}
  			w->state = FWS_L;

  #endif

  		case FWS_L:
  			if (fn->left) {
  				w->node = fn->left;
  				w->state = FWS_INIT;
  				continue;
  			}
  			w->state = FWS_R;
  		case FWS_R:
  			if (fn->right) {
  				w->node = fn->right;
  				w->state = FWS_INIT;
  				continue;
  			}
  			w->state = FWS_C;
  			w->leaf = fn->leaf;
  		case FWS_C:
  			if (w->leaf && fn->fn_flags&RTN_RTINFO) {
  				int err = w->func(w);
  				if (err)
  					return err;
  				continue;
  			}
  			w->state = FWS_U;
  		case FWS_U:
  			if (fn == w->root)
  				return 0;
  			pn = fn->parent;
  			w->node = pn;
  #ifdef CONFIG_IPV6_SUBTREES

  			if (FIB6_SUBTREE(pn) == fn) {

  				BUG_TRAP(fn->fn_flags&RTN_ROOT);
  				w->state = FWS_L;
  				continue;
  			}
  #endif
  			if (pn->left == fn) {
  				w->state = FWS_R;
  				continue;
  			}
  			if (pn->right == fn) {
  				w->state = FWS_C;
  				w->leaf = w->node->leaf;
  				continue;
  			}
  #if RT6_DEBUG >= 2
  			BUG_TRAP(0);
  #endif
  		}
  	}
  }

  static int fib6_walk(struct fib6_walker_t *w)

  {
  	int res;
  
  	w->state = FWS_INIT;
  	w->node = w->root;
  
  	fib6_walker_link(w);
  	res = fib6_walk_continue(w);
  	if (res <= 0)
  		fib6_walker_unlink(w);
  	return res;
  }
  
  static int fib6_clean_node(struct fib6_walker_t *w)
  {
  	int res;
  	struct rt6_info *rt;

  	struct fib6_cleaner_t *c = container_of(w, struct fib6_cleaner_t, w);

  	struct nl_info info = {
  		.nl_net = c->net,
  	};

  	for (rt = w->leaf; rt; rt = rt->u.dst.rt6_next) {

  		res = c->func(rt, c->arg);
  		if (res < 0) {
  			w->leaf = rt;

  			res = fib6_del(rt, &info);

  			if (res) {
  #if RT6_DEBUG >= 2
  				printk(KERN_DEBUG "fib6_clean_node: del failed: rt=%p@%p err=%d
  ", rt, rt->rt6i_node, res);
  #endif
  				continue;
  			}
  			return 0;
  		}
  		BUG_TRAP(res==0);
  	}
  	w->leaf = rt;
  	return 0;
  }
  
  /*
   *	Convenient frontend to tree walker.

   *

   *	func is called on each route.
   *		It may return -1 -> delete this route.
   *		              0  -> continue walking
   *
   *	prune==1 -> only immediate children of node (certainly,
   *	ignoring pure split nodes) will be scanned.
   */

  static void fib6_clean_tree(struct net *net, struct fib6_node *root,

  			    int (*func)(struct rt6_info *, void *arg),
  			    int prune, void *arg)

  {
  	struct fib6_cleaner_t c;
  
  	c.w.root = root;
  	c.w.func = fib6_clean_node;
  	c.w.prune = prune;
  	c.func = func;
  	c.arg = arg;

  	c.net = net;

  
  	fib6_walk(&c.w);
  }

  void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),

  		    int prune, void *arg)
  {

  	struct fib6_table *table;

  	struct hlist_node *node;

  	struct hlist_head *head;

  	unsigned int h;

  	rcu_read_lock();
  	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {

  		head = &net->ipv6.fib_table_hash[h];

  		hlist_for_each_entry_rcu(table, node, head, tb6_hlist) {

  			write_lock_bh(&table->tb6_lock);

  			fib6_clean_tree(net, &table->tb6_root,
  					func, prune, arg);

  			write_unlock_bh(&table->tb6_lock);
  		}
  	}

  	rcu_read_unlock();

  }

  static int fib6_prune_clone(struct rt6_info *rt, void *arg)
  {
  	if (rt->rt6i_flags & RTF_CACHE) {
  		RT6_TRACE("pruning clone %p
  ", rt);
  		return -1;
  	}
  
  	return 0;
  }

  static void fib6_prune_clones(struct net *net, struct fib6_node *fn,
  			      struct rt6_info *rt)

  {

  	fib6_clean_tree(net, fn, fib6_prune_clone, 1, rt);

  }
  
  /*
   *	Garbage collection
   */
  
  static struct fib6_gc_args
  {
  	int			timeout;
  	int			more;
  } gc_args;
  
  static int fib6_age(struct rt6_info *rt, void *arg)
  {
  	unsigned long now = jiffies;
  
  	/*
  	 *	check addrconf expiration here.
  	 *	Routes are expired even if they are in use.
  	 *
  	 *	Also age clones. Note, that clones are aged out
  	 *	only if they are not in use now.
  	 */
  
  	if (rt->rt6i_flags&RTF_EXPIRES && rt->rt6i_expires) {
  		if (time_after(now, rt->rt6i_expires)) {
  			RT6_TRACE("expiring %p
  ", rt);

  			return -1;
  		}
  		gc_args.more++;
  	} else if (rt->rt6i_flags & RTF_CACHE) {
  		if (atomic_read(&rt->u.dst.__refcnt) == 0 &&
  		    time_after_eq(now, rt->u.dst.lastuse + gc_args.timeout)) {
  			RT6_TRACE("aging clone %p
  ", rt);
  			return -1;
  		} else if ((rt->rt6i_flags & RTF_GATEWAY) &&
  			   (!(rt->rt6i_nexthop->flags & NTF_ROUTER))) {
  			RT6_TRACE("purging route %p via non-router but gateway
  ",
  				  rt);
  			return -1;
  		}
  		gc_args.more++;
  	}
  
  	return 0;
  }
  
  static DEFINE_SPINLOCK(fib6_gc_lock);

  void fib6_run_gc(unsigned long expires, struct net *net)

  {

  	if (expires != ~0UL) {

  		spin_lock_bh(&fib6_gc_lock);

  		gc_args.timeout = expires ? (int)expires :
  			net->ipv6.sysctl.ip6_rt_gc_interval;

  	} else {
  		local_bh_disable();
  		if (!spin_trylock(&fib6_gc_lock)) {

  			mod_timer(net->ipv6.ip6_fib_timer, jiffies + HZ);

  			local_bh_enable();
  			return;
  		}

  		gc_args.timeout = net->ipv6.sysctl.ip6_rt_gc_interval;

  	}
  	gc_args.more = 0;

  	icmp6_dst_gc(&gc_args.more);

  	fib6_clean_all(net, fib6_age, 0, NULL);

  
  	if (gc_args.more)

  		mod_timer(net->ipv6.ip6_fib_timer, jiffies +

  			  net->ipv6.sysctl.ip6_rt_gc_interval);

  	else {

  		del_timer(net->ipv6.ip6_fib_timer);
  		net->ipv6.ip6_fib_timer->expires = 0;

  	}
  	spin_unlock_bh(&fib6_gc_lock);
  }

  static void fib6_gc_timer_cb(unsigned long arg)
  {
  	fib6_run_gc(0, (struct net *)arg);
  }

  static int fib6_net_init(struct net *net)

  {

  	int ret;

  	struct timer_list *timer;

  	ret = -ENOMEM;

  	timer = kzalloc(sizeof(*timer), GFP_KERNEL);
  	if (!timer)
  		goto out;
  
  	setup_timer(timer, fib6_gc_timer_cb, (unsigned long)net);
  	net->ipv6.ip6_fib_timer = timer;

  	net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
  	if (!net->ipv6.rt6_stats)
  		goto out_timer;

  	net->ipv6.fib_table_hash =
  		kzalloc(sizeof(*net->ipv6.fib_table_hash)*FIB_TABLE_HASHSZ,
  			GFP_KERNEL);
  	if (!net->ipv6.fib_table_hash)

  		goto out_rt6_stats;

  	net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
  					  GFP_KERNEL);
  	if (!net->ipv6.fib6_main_tbl)

  		goto out_fib_table_hash;

  	net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;

  	net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;

  	net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
  		RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;

  
  #ifdef CONFIG_IPV6_MULTIPLE_TABLES

  	net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
  					   GFP_KERNEL);
  	if (!net->ipv6.fib6_local_tbl)

  		goto out_fib6_main_tbl;

  	net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;

  	net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;

  	net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
  		RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;

  #endif

  	fib6_tables_init(net);

  	ret = 0;

  out:
  	return ret;

  #ifdef CONFIG_IPV6_MULTIPLE_TABLES

  out_fib6_main_tbl:

  	kfree(net->ipv6.fib6_main_tbl);

  #endif

  out_fib_table_hash:

  	kfree(net->ipv6.fib_table_hash);

  out_rt6_stats:
  	kfree(net->ipv6.rt6_stats);

  out_timer:
  	kfree(timer);

  	goto out;
   }
  
  static void fib6_net_exit(struct net *net)
  {

  	rt6_ifdown(net, NULL);

  	del_timer_sync(net->ipv6.ip6_fib_timer);

  	kfree(net->ipv6.ip6_fib_timer);

  #ifdef CONFIG_IPV6_MULTIPLE_TABLES
  	kfree(net->ipv6.fib6_local_tbl);
  #endif
  	kfree(net->ipv6.fib6_main_tbl);
  	kfree(net->ipv6.fib_table_hash);

  	kfree(net->ipv6.rt6_stats);

  }
  
  static struct pernet_operations fib6_net_ops = {
  	.init = fib6_net_init,
  	.exit = fib6_net_exit,
  };
  
  int __init fib6_init(void)
  {
  	int ret = -ENOMEM;

  	fib6_node_kmem = kmem_cache_create("fib6_nodes",
  					   sizeof(struct fib6_node),
  					   0, SLAB_HWCACHE_ALIGN,
  					   NULL);
  	if (!fib6_node_kmem)
  		goto out;
  
  	ret = register_pernet_subsys(&fib6_net_ops);
  	if (ret)

  		goto out_kmem_cache_create;

  
  	ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib);
  	if (ret)
  		goto out_unregister_subsys;
  out:
  	return ret;
  
  out_unregister_subsys:
  	unregister_pernet_subsys(&fib6_net_ops);

  out_kmem_cache_create:
  	kmem_cache_destroy(fib6_node_kmem);
  	goto out;

  }
  
  void fib6_gc_cleanup(void)
  {

  	unregister_pernet_subsys(&fib6_net_ops);

  	kmem_cache_destroy(fib6_node_kmem);
  }