Linux-2.6.12-rc2

[mirror_ubuntu-artful-kernel.git] / net / ipv4 / fib_hash.c

/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              IPv4 FIB: lookup engine and maintenance routines.
 *
 * Version:     $Id: fib_hash.c,v 1.13 2001/10/31 21:55:54 davem Exp $
 *
 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 *              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.
 */

#include <linux/config.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/bitops.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/init.h>

#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/tcp.h>
#include <net/sock.h>
#include <net/ip_fib.h>

#include "fib_lookup.h"

static kmem_cache_t *fn_hash_kmem;
static kmem_cache_t *fn_alias_kmem;

struct fib_node {
        struct hlist_node       fn_hash;
        struct list_head        fn_alias;
        u32                     fn_key;
};

struct fn_zone {
        struct fn_zone          *fz_next;       /* Next not empty zone  */
        struct hlist_head       *fz_hash;       /* Hash table pointer   */
        int                     fz_nent;        /* Number of entries    */

        int                     fz_divisor;     /* Hash divisor         */
        u32                     fz_hashmask;    /* (fz_divisor - 1)     */
#define FZ_HASHMASK(fz)         ((fz)->fz_hashmask)

        int                     fz_order;       /* Zone order           */
        u32                     fz_mask;
#define FZ_MASK(fz)             ((fz)->fz_mask)
};

/* NOTE. On fast computers evaluation of fz_hashmask and fz_mask
 * can be cheaper than memory lookup, so that FZ_* macros are used.
 */

struct fn_hash {
        struct fn_zone  *fn_zones[33];
        struct fn_zone  *fn_zone_list;
};

static inline u32 fn_hash(u32 key, struct fn_zone *fz)
{
        u32 h = ntohl(key)>>(32 - fz->fz_order);
        h ^= (h>>20);
        h ^= (h>>10);
        h ^= (h>>5);
        h &= FZ_HASHMASK(fz);
        return h;
}

static inline u32 fz_key(u32 dst, struct fn_zone *fz)
{
        return dst & FZ_MASK(fz);
}

static DEFINE_RWLOCK(fib_hash_lock);
static unsigned int fib_hash_genid;

#define FZ_MAX_DIVISOR ((PAGE_SIZE<<MAX_ORDER) / sizeof(struct hlist_head))

static struct hlist_head *fz_hash_alloc(int divisor)
{
        unsigned long size = divisor * sizeof(struct hlist_head);

        if (size <= PAGE_SIZE) {
                return kmalloc(size, GFP_KERNEL);
        } else {
                return (struct hlist_head *)
                        __get_free_pages(GFP_KERNEL, get_order(size));
        }
}

/* The fib hash lock must be held when this is called. */
static inline void fn_rebuild_zone(struct fn_zone *fz,
                                   struct hlist_head *old_ht,
                                   int old_divisor)
{
        int i;

        for (i = 0; i < old_divisor; i++) {
                struct hlist_node *node, *n;
                struct fib_node *f;

                hlist_for_each_entry_safe(f, node, n, &old_ht[i], fn_hash) {
                        struct hlist_head *new_head;

                        hlist_del(&f->fn_hash);

                        new_head = &fz->fz_hash[fn_hash(f->fn_key, fz)];
                        hlist_add_head(&f->fn_hash, new_head);
                }
        }
}

static void fz_hash_free(struct hlist_head *hash, int divisor)
{
        unsigned long size = divisor * sizeof(struct hlist_head);

        if (size <= PAGE_SIZE)
                kfree(hash);
        else
                free_pages((unsigned long)hash, get_order(size));
}

static void fn_rehash_zone(struct fn_zone *fz)
{
        struct hlist_head *ht, *old_ht;
        int old_divisor, new_divisor;
        u32 new_hashmask;
                
        old_divisor = fz->fz_divisor;

        switch (old_divisor) {
        case 16:
                new_divisor = 256;
                break;
        case 256:
                new_divisor = 1024;
                break;
        default:
                if ((old_divisor << 1) > FZ_MAX_DIVISOR) {
                        printk(KERN_CRIT "route.c: bad divisor %d!\n", old_divisor);
                        return;
                }
                new_divisor = (old_divisor << 1);
                break;
        }

        new_hashmask = (new_divisor - 1);

#if RT_CACHE_DEBUG >= 2
        printk("fn_rehash_zone: hash for zone %d grows from %d\n", fz->fz_order, old_divisor);
#endif

        ht = fz_hash_alloc(new_divisor);

        if (ht) {
                memset(ht, 0, new_divisor * sizeof(struct hlist_head));

                write_lock_bh(&fib_hash_lock);
                old_ht = fz->fz_hash;
                fz->fz_hash = ht;
                fz->fz_hashmask = new_hashmask;
                fz->fz_divisor = new_divisor;
                fn_rebuild_zone(fz, old_ht, old_divisor);
                fib_hash_genid++;
                write_unlock_bh(&fib_hash_lock);

                fz_hash_free(old_ht, old_divisor);
        }
}

static inline void fn_free_node(struct fib_node * f)
{
        kmem_cache_free(fn_hash_kmem, f);
}

static inline void fn_free_alias(struct fib_alias *fa)
{
        fib_release_info(fa->fa_info);
        kmem_cache_free(fn_alias_kmem, fa);
}

static struct fn_zone *
fn_new_zone(struct fn_hash *table, int z)
{
        int i;
        struct fn_zone *fz = kmalloc(sizeof(struct fn_zone), GFP_KERNEL);
        if (!fz)
                return NULL;

        memset(fz, 0, sizeof(struct fn_zone));
        if (z) {
                fz->fz_divisor = 16;
        } else {
                fz->fz_divisor = 1;
        }
        fz->fz_hashmask = (fz->fz_divisor - 1);
        fz->fz_hash = fz_hash_alloc(fz->fz_divisor);
        if (!fz->fz_hash) {
                kfree(fz);
                return NULL;
        }
        memset(fz->fz_hash, 0, fz->fz_divisor * sizeof(struct hlist_head *));
        fz->fz_order = z;
        fz->fz_mask = inet_make_mask(z);

        /* Find the first not empty zone with more specific mask */
        for (i=z+1; i<=32; i++)
                if (table->fn_zones[i])
                        break;
        write_lock_bh(&fib_hash_lock);
        if (i>32) {
                /* No more specific masks, we are the first. */
                fz->fz_next = table->fn_zone_list;
                table->fn_zone_list = fz;
        } else {
                fz->fz_next = table->fn_zones[i]->fz_next;
                table->fn_zones[i]->fz_next = fz;
        }
        table->fn_zones[z] = fz;
        fib_hash_genid++;
        write_unlock_bh(&fib_hash_lock);
        return fz;
}

static int
fn_hash_lookup(struct fib_table *tb, const struct flowi *flp, struct fib_result *res)
{
        int err;
        struct fn_zone *fz;
        struct fn_hash *t = (struct fn_hash*)tb->tb_data;

        read_lock(&fib_hash_lock);
        for (fz = t->fn_zone_list; fz; fz = fz->fz_next) {
                struct hlist_head *head;
                struct hlist_node *node;
                struct fib_node *f;
                u32 k = fz_key(flp->fl4_dst, fz);

                head = &fz->fz_hash[fn_hash(k, fz)];
                hlist_for_each_entry(f, node, head, fn_hash) {
                        if (f->fn_key != k)
                                continue;

                        err = fib_semantic_match(&f->fn_alias,
                                                 flp, res,
                                                 f->fn_key, fz->fz_mask,
                                                 fz->fz_order);
                        if (err <= 0)
                                goto out;
                }
        }
        err = 1;
out:
        read_unlock(&fib_hash_lock);
        return err;
}

static int fn_hash_last_dflt=-1;

static void
fn_hash_select_default(struct fib_table *tb, const struct flowi *flp, struct fib_result *res)
{
        int order, last_idx;
        struct hlist_node *node;
        struct fib_node *f;
        struct fib_info *fi = NULL;
        struct fib_info *last_resort;
        struct fn_hash *t = (struct fn_hash*)tb->tb_data;
        struct fn_zone *fz = t->fn_zones[0];

        if (fz == NULL)
                return;

        last_idx = -1;
        last_resort = NULL;
        order = -1;

        read_lock(&fib_hash_lock);
        hlist_for_each_entry(f, node, &fz->fz_hash[0], fn_hash) {
                struct fib_alias *fa;

                list_for_each_entry(fa, &f->fn_alias, fa_list) {
                        struct fib_info *next_fi = fa->fa_info;

                        if (fa->fa_scope != res->scope ||
                            fa->fa_type != RTN_UNICAST)
                                continue;

                        if (next_fi->fib_priority > res->fi->fib_priority)
                                break;
                        if (!next_fi->fib_nh[0].nh_gw ||
                            next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
                                continue;
                        fa->fa_state |= FA_S_ACCESSED;

                        if (fi == NULL) {
                                if (next_fi != res->fi)
                                        break;
                        } else if (!fib_detect_death(fi, order, &last_resort,
                                                     &last_idx, &fn_hash_last_dflt)) {
                                if (res->fi)
                                        fib_info_put(res->fi);
                                res->fi = fi;
                                atomic_inc(&fi->fib_clntref);
                                fn_hash_last_dflt = order;
                                goto out;
                        }
                        fi = next_fi;
                        order++;
                }
        }

        if (order <= 0 || fi == NULL) {
                fn_hash_last_dflt = -1;
                goto out;
        }

        if (!fib_detect_death(fi, order, &last_resort, &last_idx, &fn_hash_last_dflt)) {
                if (res->fi)
                        fib_info_put(res->fi);
                res->fi = fi;
                atomic_inc(&fi->fib_clntref);
                fn_hash_last_dflt = order;
                goto out;
        }

        if (last_idx >= 0) {
                if (res->fi)
                        fib_info_put(res->fi);
                res->fi = last_resort;
                if (last_resort)
                        atomic_inc(&last_resort->fib_clntref);
        }
        fn_hash_last_dflt = last_idx;
out:
        read_unlock(&fib_hash_lock);
}

/* Insert node F to FZ. */
static inline void fib_insert_node(struct fn_zone *fz, struct fib_node *f)
{
        struct hlist_head *head = &fz->fz_hash[fn_hash(f->fn_key, fz)];

        hlist_add_head(&f->fn_hash, head);
}

/* Return the node in FZ matching KEY. */
static struct fib_node *fib_find_node(struct fn_zone *fz, u32 key)
{
        struct hlist_head *head = &fz->fz_hash[fn_hash(key, fz)];
        struct hlist_node *node;
        struct fib_node *f;

        hlist_for_each_entry(f, node, head, fn_hash) {
                if (f->fn_key == key)
                        return f;
        }

        return NULL;
}

static int
fn_hash_insert(struct fib_table *tb, struct rtmsg *r, struct kern_rta *rta,
               struct nlmsghdr *n, struct netlink_skb_parms *req)
{
        struct fn_hash *table = (struct fn_hash *) tb->tb_data;
        struct fib_node *new_f, *f;
        struct fib_alias *fa, *new_fa;
        struct fn_zone *fz;
        struct fib_info *fi;
        int z = r->rtm_dst_len;
        int type = r->rtm_type;
        u8 tos = r->rtm_tos;
        u32 key;
        int err;

        if (z > 32)
                return -EINVAL;
        fz = table->fn_zones[z];
        if (!fz && !(fz = fn_new_zone(table, z)))
                return -ENOBUFS;

        key = 0;
        if (rta->rta_dst) {
                u32 dst;
                memcpy(&dst, rta->rta_dst, 4);
                if (dst & ~FZ_MASK(fz))
                        return -EINVAL;
                key = fz_key(dst, fz);
        }

        if  ((fi = fib_create_info(r, rta, n, &err)) == NULL)
                return err;

        if (fz->fz_nent > (fz->fz_divisor<<1) &&
            fz->fz_divisor < FZ_MAX_DIVISOR &&
            (z==32 || (1<<z) > fz->fz_divisor))
                fn_rehash_zone(fz);

        f = fib_find_node(fz, key);

        if (!f)
                fa = NULL;
        else
                fa = fib_find_alias(&f->fn_alias, tos, fi->fib_priority);

        /* Now fa, if non-NULL, points to the first fib alias
         * with the same keys [prefix,tos,priority], if such key already
         * exists or to the node before which we will insert new one.
         *
         * If fa is NULL, we will need to allocate a new one and
         * insert to the head of f.
         *
         * If f is NULL, no fib node matched the destination key
         * and we need to allocate a new one of those as well.
         */

        if (fa && fa->fa_tos == tos &&
            fa->fa_info->fib_priority == fi->fib_priority) {
                struct fib_alias *fa_orig;

                err = -EEXIST;
                if (n->nlmsg_flags & NLM_F_EXCL)
                        goto out;

                if (n->nlmsg_flags & NLM_F_REPLACE) {
                        struct fib_info *fi_drop;
                        u8 state;

                        write_lock_bh(&fib_hash_lock);
                        fi_drop = fa->fa_info;
                        fa->fa_info = fi;
                        fa->fa_type = type;
                        fa->fa_scope = r->rtm_scope;
                        state = fa->fa_state;
                        fa->fa_state &= ~FA_S_ACCESSED;
                        fib_hash_genid++;
                        write_unlock_bh(&fib_hash_lock);

                        fib_release_info(fi_drop);
                        if (state & FA_S_ACCESSED)
                                rt_cache_flush(-1);
                        return 0;
                }

                /* Error if we find a perfect match which
                 * uses the same scope, type, and nexthop
                 * information.
                 */
                fa_orig = fa;
                fa = list_entry(fa->fa_list.prev, struct fib_alias, fa_list);
                list_for_each_entry_continue(fa, &f->fn_alias, fa_list) {
                        if (fa->fa_tos != tos)
                                break;
                        if (fa->fa_info->fib_priority != fi->fib_priority)
                                break;
                        if (fa->fa_type == type &&
                            fa->fa_scope == r->rtm_scope &&
                            fa->fa_info == fi)
                                goto out;
                }
                if (!(n->nlmsg_flags & NLM_F_APPEND))
                        fa = fa_orig;
        }

        err = -ENOENT;
        if (!(n->nlmsg_flags&NLM_F_CREATE))
                goto out;

        err = -ENOBUFS;
        new_fa = kmem_cache_alloc(fn_alias_kmem, SLAB_KERNEL);
        if (new_fa == NULL)
                goto out;

        new_f = NULL;
        if (!f) {
                new_f = kmem_cache_alloc(fn_hash_kmem, SLAB_KERNEL);
                if (new_f == NULL)
                        goto out_free_new_fa;

                INIT_HLIST_NODE(&new_f->fn_hash);
                INIT_LIST_HEAD(&new_f->fn_alias);
                new_f->fn_key = key;
                f = new_f;
        }

        new_fa->fa_info = fi;
        new_fa->fa_tos = tos;
        new_fa->fa_type = type;
        new_fa->fa_scope = r->rtm_scope;
        new_fa->fa_state = 0;

        /*
         * Insert new entry to the list.
         */

        write_lock_bh(&fib_hash_lock);
        if (new_f)
                fib_insert_node(fz, new_f);
        list_add_tail(&new_fa->fa_list,
                 (fa ? &fa->fa_list : &f->fn_alias));
        fib_hash_genid++;
        write_unlock_bh(&fib_hash_lock);

        if (new_f)
                fz->fz_nent++;
        rt_cache_flush(-1);

        rtmsg_fib(RTM_NEWROUTE, key, new_fa, z, tb->tb_id, n, req);
        return 0;

out_free_new_fa:
        kmem_cache_free(fn_alias_kmem, new_fa);
out:
        fib_release_info(fi);
        return err;
}


static int
fn_hash_delete(struct fib_table *tb, struct rtmsg *r, struct kern_rta *rta,
               struct nlmsghdr *n, struct netlink_skb_parms *req)
{
        struct fn_hash *table = (struct fn_hash*)tb->tb_data;
        struct fib_node *f;
        struct fib_alias *fa, *fa_to_delete;
        int z = r->rtm_dst_len;
        struct fn_zone *fz;
        u32 key;
        u8 tos = r->rtm_tos;

        if (z > 32)
                return -EINVAL;
        if ((fz  = table->fn_zones[z]) == NULL)
                return -ESRCH;

        key = 0;
        if (rta->rta_dst) {
                u32 dst;
                memcpy(&dst, rta->rta_dst, 4);
                if (dst & ~FZ_MASK(fz))
                        return -EINVAL;
                key = fz_key(dst, fz);
        }

        f = fib_find_node(fz, key);

        if (!f)
                fa = NULL;
        else
                fa = fib_find_alias(&f->fn_alias, tos, 0);
        if (!fa)
                return -ESRCH;

        fa_to_delete = NULL;
        fa = list_entry(fa->fa_list.prev, struct fib_alias, fa_list);
        list_for_each_entry_continue(fa, &f->fn_alias, fa_list) {
                struct fib_info *fi = fa->fa_info;

                if (fa->fa_tos != tos)
                        break;

                if ((!r->rtm_type ||
                     fa->fa_type == r->rtm_type) &&
                    (r->rtm_scope == RT_SCOPE_NOWHERE ||
                     fa->fa_scope == r->rtm_scope) &&
                    (!r->rtm_protocol ||
                     fi->fib_protocol == r->rtm_protocol) &&
                    fib_nh_match(r, n, rta, fi) == 0) {
                        fa_to_delete = fa;
                        break;
                }
        }

        if (fa_to_delete) {
                int kill_fn;

                fa = fa_to_delete;
                rtmsg_fib(RTM_DELROUTE, key, fa, z, tb->tb_id, n, req);

                kill_fn = 0;
                write_lock_bh(&fib_hash_lock);
                list_del(&fa->fa_list);
                if (list_empty(&f->fn_alias)) {
                        hlist_del(&f->fn_hash);
                        kill_fn = 1;
                }
                fib_hash_genid++;
                write_unlock_bh(&fib_hash_lock);

                if (fa->fa_state & FA_S_ACCESSED)
                        rt_cache_flush(-1);
                fn_free_alias(fa);
                if (kill_fn) {
                        fn_free_node(f);
                        fz->fz_nent--;
                }

                return 0;
        }
        return -ESRCH;
}

static int fn_flush_list(struct fn_zone *fz, int idx)
{
        struct hlist_head *head = &fz->fz_hash[idx];
        struct hlist_node *node, *n;
        struct fib_node *f;
        int found = 0;

        hlist_for_each_entry_safe(f, node, n, head, fn_hash) {
                struct fib_alias *fa, *fa_node;
                int kill_f;

                kill_f = 0;
                list_for_each_entry_safe(fa, fa_node, &f->fn_alias, fa_list) {
                        struct fib_info *fi = fa->fa_info;

                        if (fi && (fi->fib_flags&RTNH_F_DEAD)) {
                                write_lock_bh(&fib_hash_lock);
                                list_del(&fa->fa_list);
                                if (list_empty(&f->fn_alias)) {
                                        hlist_del(&f->fn_hash);
                                        kill_f = 1;
                                }
                                fib_hash_genid++;
                                write_unlock_bh(&fib_hash_lock);

                                fn_free_alias(fa);
                                found++;
                        }
                }
                if (kill_f) {
                        fn_free_node(f);
                        fz->fz_nent--;
                }
        }
        return found;
}

static int fn_hash_flush(struct fib_table *tb)
{
        struct fn_hash *table = (struct fn_hash *) tb->tb_data;
        struct fn_zone *fz;
        int found = 0;

        for (fz = table->fn_zone_list; fz; fz = fz->fz_next) {
                int i;

                for (i = fz->fz_divisor - 1; i >= 0; i--)
                        found += fn_flush_list(fz, i);
        }
        return found;
}


static inline int
fn_hash_dump_bucket(struct sk_buff *skb, struct netlink_callback *cb,
                     struct fib_table *tb,
                     struct fn_zone *fz,
                     struct hlist_head *head)
{
        struct hlist_node *node;
        struct fib_node *f;
        int i, s_i;

        s_i = cb->args[3];
        i = 0;
        hlist_for_each_entry(f, node, head, fn_hash) {
                struct fib_alias *fa;

                list_for_each_entry(fa, &f->fn_alias, fa_list) {
                        if (i < s_i)
                                goto next;

                        if (fib_dump_info(skb, NETLINK_CB(cb->skb).pid,
                                          cb->nlh->nlmsg_seq,
                                          RTM_NEWROUTE,
                                          tb->tb_id,
                                          fa->fa_type,
                                          fa->fa_scope,
                                          &f->fn_key,
                                          fz->fz_order,
                                          fa->fa_tos,
                                          fa->fa_info) < 0) {
                                cb->args[3] = i;
                                return -1;
                        }
                next:
                        i++;
                }
        }
        cb->args[3] = i;
        return skb->len;
}

static inline int
fn_hash_dump_zone(struct sk_buff *skb, struct netlink_callback *cb,
                   struct fib_table *tb,
                   struct fn_zone *fz)
{
        int h, s_h;

        s_h = cb->args[2];
        for (h=0; h < fz->fz_divisor; h++) {
                if (h < s_h) continue;
                if (h > s_h)
                        memset(&cb->args[3], 0,
                               sizeof(cb->args) - 3*sizeof(cb->args[0]));
                if (fz->fz_hash == NULL ||
                    hlist_empty(&fz->fz_hash[h]))
                        continue;
                if (fn_hash_dump_bucket(skb, cb, tb, fz, &fz->fz_hash[h])<0) {
                        cb->args[2] = h;
                        return -1;
                }
        }
        cb->args[2] = h;
        return skb->len;
}

static int fn_hash_dump(struct fib_table *tb, struct sk_buff *skb, struct netlink_callback *cb)
{
        int m, s_m;
        struct fn_zone *fz;
        struct fn_hash *table = (struct fn_hash*)tb->tb_data;

        s_m = cb->args[1];
        read_lock(&fib_hash_lock);
        for (fz = table->fn_zone_list, m=0; fz; fz = fz->fz_next, m++) {
                if (m < s_m) continue;
                if (m > s_m)
                        memset(&cb->args[2], 0,
                               sizeof(cb->args) - 2*sizeof(cb->args[0]));
                if (fn_hash_dump_zone(skb, cb, tb, fz) < 0) {
                        cb->args[1] = m;
                        read_unlock(&fib_hash_lock);
                        return -1;
                }
        }
        read_unlock(&fib_hash_lock);
        cb->args[1] = m;
        return skb->len;
}

#ifdef CONFIG_IP_MULTIPLE_TABLES
struct fib_table * fib_hash_init(int id)
#else
struct fib_table * __init fib_hash_init(int id)
#endif
{
        struct fib_table *tb;

        if (fn_hash_kmem == NULL)
                fn_hash_kmem = kmem_cache_create("ip_fib_hash",
                                                 sizeof(struct fib_node),
                                                 0, SLAB_HWCACHE_ALIGN,
                                                 NULL, NULL);

        if (fn_alias_kmem == NULL)
                fn_alias_kmem = kmem_cache_create("ip_fib_alias",
                                                  sizeof(struct fib_alias),
                                                  0, SLAB_HWCACHE_ALIGN,
                                                  NULL, NULL);

        tb = kmalloc(sizeof(struct fib_table) + sizeof(struct fn_hash),
                     GFP_KERNEL);
        if (tb == NULL)
                return NULL;

        tb->tb_id = id;
        tb->tb_lookup = fn_hash_lookup;
        tb->tb_insert = fn_hash_insert;
        tb->tb_delete = fn_hash_delete;
        tb->tb_flush = fn_hash_flush;
        tb->tb_select_default = fn_hash_select_default;
        tb->tb_dump = fn_hash_dump;
        memset(tb->tb_data, 0, sizeof(struct fn_hash));
        return tb;
}

/* ------------------------------------------------------------------------ */
#ifdef CONFIG_PROC_FS

struct fib_iter_state {
        struct fn_zone  *zone;
        int             bucket;
        struct hlist_head *hash_head;
        struct fib_node *fn;
        struct fib_alias *fa;
        loff_t pos;
        unsigned int genid;
        int valid;
};

static struct fib_alias *fib_get_first(struct seq_file *seq)
{
        struct fib_iter_state *iter = seq->private;
        struct fn_hash *table = (struct fn_hash *) ip_fib_main_table->tb_data;

        iter->bucket    = 0;
        iter->hash_head = NULL;
        iter->fn        = NULL;
        iter->fa        = NULL;
        iter->pos       = 0;
        iter->genid     = fib_hash_genid;
        iter->valid     = 1;

        for (iter->zone = table->fn_zone_list; iter->zone;
             iter->zone = iter->zone->fz_next) {
                int maxslot;

                if (!iter->zone->fz_nent)
                        continue;

                iter->hash_head = iter->zone->fz_hash;
                maxslot = iter->zone->fz_divisor;

                for (iter->bucket = 0; iter->bucket < maxslot;
                     ++iter->bucket, ++iter->hash_head) {
                        struct hlist_node *node;
                        struct fib_node *fn;

                        hlist_for_each_entry(fn,node,iter->hash_head,fn_hash) {
                                struct fib_alias *fa;

                                list_for_each_entry(fa,&fn->fn_alias,fa_list) {
                                        iter->fn = fn;
                                        iter->fa = fa;
                                        goto out;
                                }
                        }
                }
        }
out:
        return iter->fa;
}

static struct fib_alias *fib_get_next(struct seq_file *seq)
{
        struct fib_iter_state *iter = seq->private;
        struct fib_node *fn;
        struct fib_alias *fa;

        /* Advance FA, if any. */
        fn = iter->fn;
        fa = iter->fa;
        if (fa) {
                BUG_ON(!fn);
                list_for_each_entry_continue(fa, &fn->fn_alias, fa_list) {
                        iter->fa = fa;
                        goto out;
                }
        }

        fa = iter->fa = NULL;

        /* Advance FN. */
        if (fn) {
                struct hlist_node *node = &fn->fn_hash;
                hlist_for_each_entry_continue(fn, node, fn_hash) {
                        iter->fn = fn;

                        list_for_each_entry(fa, &fn->fn_alias, fa_list) {
                                iter->fa = fa;
                                goto out;
                        }
                }
        }

        fn = iter->fn = NULL;

        /* Advance hash chain. */
        if (!iter->zone)
                goto out;

        for (;;) {
                struct hlist_node *node;
                int maxslot;

                maxslot = iter->zone->fz_divisor;

                while (++iter->bucket < maxslot) {
                        iter->hash_head++;

                        hlist_for_each_entry(fn, node, iter->hash_head, fn_hash) {
                                list_for_each_entry(fa, &fn->fn_alias, fa_list) {
                                        iter->fn = fn;
                                        iter->fa = fa;
                                        goto out;
                                }
                        }
                }

                iter->zone = iter->zone->fz_next;

                if (!iter->zone)
                        goto out;
                
                iter->bucket = 0;
                iter->hash_head = iter->zone->fz_hash;

                hlist_for_each_entry(fn, node, iter->hash_head, fn_hash) {
                        list_for_each_entry(fa, &fn->fn_alias, fa_list) {
                                iter->fn = fn;
                                iter->fa = fa;
                                goto out;
                        }
                }
        }
out:
        iter->pos++;
        return fa;
}

static struct fib_alias *fib_get_idx(struct seq_file *seq, loff_t pos)
{
        struct fib_iter_state *iter = seq->private;
        struct fib_alias *fa;
        
        if (iter->valid && pos >= iter->pos && iter->genid == fib_hash_genid) {
                fa   = iter->fa;
                pos -= iter->pos;
        } else
                fa = fib_get_first(seq);

        if (fa)
                while (pos && (fa = fib_get_next(seq)))
                        --pos;
        return pos ? NULL : fa;
}

static void *fib_seq_start(struct seq_file *seq, loff_t *pos)
{
        void *v = NULL;

        read_lock(&fib_hash_lock);
        if (ip_fib_main_table)
                v = *pos ? fib_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
        return v;
}

static void *fib_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        ++*pos;
        return v == SEQ_START_TOKEN ? fib_get_first(seq) : fib_get_next(seq);
}

static void fib_seq_stop(struct seq_file *seq, void *v)
{
        read_unlock(&fib_hash_lock);
}

static unsigned fib_flag_trans(int type, u32 mask, struct fib_info *fi)
{
        static unsigned type2flags[RTN_MAX + 1] = {
                [7] = RTF_REJECT, [8] = RTF_REJECT,
        };
        unsigned flags = type2flags[type];

        if (fi && fi->fib_nh->nh_gw)
                flags |= RTF_GATEWAY;
        if (mask == 0xFFFFFFFF)
                flags |= RTF_HOST;
        flags |= RTF_UP;
        return flags;
}

/* 
 *      This outputs /proc/net/route.
 *
 *      It always works in backward compatibility mode.
 *      The format of the file is not supposed to be changed.
 */
static int fib_seq_show(struct seq_file *seq, void *v)
{
        struct fib_iter_state *iter;
        char bf[128];
        u32 prefix, mask;
        unsigned flags;
        struct fib_node *f;
        struct fib_alias *fa;
        struct fib_info *fi;

        if (v == SEQ_START_TOKEN) {
                seq_printf(seq, "%-127s\n", "Iface\tDestination\tGateway "
                           "\tFlags\tRefCnt\tUse\tMetric\tMask\t\tMTU"
                           "\tWindow\tIRTT");
                goto out;
        }

        iter    = seq->private;
        f       = iter->fn;
        fa      = iter->fa;
        fi      = fa->fa_info;
        prefix  = f->fn_key;
        mask    = FZ_MASK(iter->zone);
        flags   = fib_flag_trans(fa->fa_type, mask, fi);
        if (fi)
                snprintf(bf, sizeof(bf),
                         "%s\t%08X\t%08X\t%04X\t%d\t%u\t%d\t%08X\t%d\t%u\t%u",
                         fi->fib_dev ? fi->fib_dev->name : "*", prefix,
                         fi->fib_nh->nh_gw, flags, 0, 0, fi->fib_priority,
                         mask, (fi->fib_advmss ? fi->fib_advmss + 40 : 0),
                         fi->fib_window,
                         fi->fib_rtt >> 3);
        else
                snprintf(bf, sizeof(bf),
                         "*\t%08X\t%08X\t%04X\t%d\t%u\t%d\t%08X\t%d\t%u\t%u",
                         prefix, 0, flags, 0, 0, 0, mask, 0, 0, 0);
        seq_printf(seq, "%-127s\n", bf);
out:
        return 0;
}

static struct seq_operations fib_seq_ops = {
        .start  = fib_seq_start,
        .next   = fib_seq_next,
        .stop   = fib_seq_stop,
        .show   = fib_seq_show,
};

static int fib_seq_open(struct inode *inode, struct file *file)
{
        struct seq_file *seq;
        int rc = -ENOMEM;
        struct fib_iter_state *s = kmalloc(sizeof(*s), GFP_KERNEL);
       
        if (!s)
                goto out;

        rc = seq_open(file, &fib_seq_ops);
        if (rc)
                goto out_kfree;

        seq          = file->private_data;
        seq->private = s;
        memset(s, 0, sizeof(*s));
out:
        return rc;
out_kfree:
        kfree(s);
        goto out;
}

static struct file_operations fib_seq_fops = {
        .owner          = THIS_MODULE,
        .open           = fib_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release_private,
};

int __init fib_proc_init(void)
{
        if (!proc_net_fops_create("route", S_IRUGO, &fib_seq_fops))
                return -ENOMEM;
        return 0;
}

void __init fib_proc_exit(void)
{
        proc_net_remove("route");
}
#endif /* CONFIG_PROC_FS */