/*
 * 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 <asm/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>

#define FTprint(a...)
/*
   printk(KERN_DEBUG a)
 */

static kmem_cache_t * fn_hash_kmem;

/*
   These bizarre types are just to force strict type checking.
   When I reversed order of bytes and changed to natural mask lengths,
   I forgot to make fixes in several places. Now I am lazy to return
   it back.
 */

typedef struct {
        u32     datum;
} fn_key_t;

typedef struct {
        u32     datum;
} fn_hash_idx_t;

struct fib_node
{
        struct fib_node         *fn_next;
        struct fib_info         *fn_info;
#define FIB_INFO(f)     ((f)->fn_info)
        fn_key_t                fn_key;
        u8                      fn_tos;
        u8                      fn_type;
        u8                      fn_scope;
        u8                      fn_state;
};

#define FN_S_ZOMBIE     1
#define FN_S_ACCESSED   2

static int fib_hash_zombies;

struct fn_zone
{
        struct fn_zone  *fz_next;       /* Next not empty zone  */
        struct fib_node **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__ fn_hash_idx_t fn_hash(fn_key_t key, struct fn_zone *fz)
{
        u32 h = ntohl(key.datum)>>(32 - fz->fz_order);
        h ^= (h>>20);
        h ^= (h>>10);
        h ^= (h>>5);
        h &= FZ_HASHMASK(fz);
        return *(fn_hash_idx_t*)&h;
}

#define fz_key_0(key)           ((key).datum = 0)
#define fz_prefix(key,fz)       ((key).datum)

static __inline__ fn_key_t fz_key(u32 dst, struct fn_zone *fz)
{
        fn_key_t k;
        k.datum = dst & FZ_MASK(fz);
        return k;
}

static __inline__ struct fib_node ** fz_chain_p(fn_key_t key, struct fn_zone *fz)
{
        return &fz->fz_hash[fn_hash(key, fz).datum];
}

static __inline__ struct fib_node * fz_chain(fn_key_t key, struct fn_zone *fz)
{
        return fz->fz_hash[fn_hash(key, fz).datum];
}

static __inline__ int fn_key_eq(fn_key_t a, fn_key_t b)
{
        return a.datum == b.datum;
}

static __inline__ int fn_key_leq(fn_key_t a, fn_key_t b)
{
        return a.datum <= b.datum;
}

static rwlock_t fib_hash_lock = RW_LOCK_UNLOCKED;

#define FZ_MAX_DIVISOR ((PAGE_SIZE<<MAX_ORDER) / sizeof(struct fib_node *))

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

        if (divisor <= 1024) {
                return kmalloc(size, GFP_KERNEL);
        } else {
                return (struct fib_node **)
                        __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 fib_node **old_ht,
                                       int old_divisor)
{
        int i;
        struct fib_node *f, **fp, *next;

        for (i=0; i<old_divisor; i++) {
                for (f=old_ht[i]; f; f=next) {
                        next = f->fn_next;
                        for (fp = fz_chain_p(f->fn_key, fz);
                             *fp && fn_key_leq((*fp)->fn_key, f->fn_key);
                             fp = &(*fp)->fn_next)
                                /* NONE */;
                        f->fn_next = *fp;
                        *fp = f;
                }
        }
}

static void fz_hash_free(struct fib_node **hash, int divisor)
{
        if (divisor <= 1024)
                kfree(hash);
        else
                free_pages((unsigned long) hash,
                           get_order(divisor * sizeof(struct fib_node *)));
}

static void fn_rehash_zone(struct fn_zone *fz)
{
        struct fib_node **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 fib_node*));

                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);
                write_unlock_bh(&fib_hash_lock);

                fz_hash_free(old_ht, old_divisor);
        }
}

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


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 fib_node*));
        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;
        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 fib_node *f;
                fn_key_t k = fz_key(flp->fl4_dst, fz);

                for (f = fz_chain(k, fz); f; f = f->fn_next) {
                        if (!fn_key_eq(k, f->fn_key)) {
                                if (fn_key_leq(k, f->fn_key))
                                        break;
                                else
                                        continue;
                        }
#ifdef CONFIG_IP_ROUTE_TOS
                        if (f->fn_tos && f->fn_tos != flp->fl4_tos)
                                continue;
#endif
                        f->fn_state |= FN_S_ACCESSED;

                        if (f->fn_state&FN_S_ZOMBIE)
                                continue;
                        if (f->fn_scope < flp->fl4_scope)
                                continue;

                        err = fib_semantic_match(f->fn_type, FIB_INFO(f), flp, res);
                        if (err == 0) {
                                res->type = f->fn_type;
                                res->scope = f->fn_scope;
                                res->prefixlen = fz->fz_order;
                                goto out;
                        }
                        if (err < 0)
                                goto out;
                }
        }
        err = 1;
out:
        read_unlock(&fib_hash_lock);
        return err;
}

static int fn_hash_last_dflt=-1;

static int fib_detect_death(struct fib_info *fi, int order,
                            struct fib_info **last_resort, int *last_idx)
{
        struct neighbour *n;
        int state = NUD_NONE;

        n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
        if (n) {
                state = n->nud_state;
                neigh_release(n);
        }
        if (state==NUD_REACHABLE)
                return 0;
        if ((state&NUD_VALID) && order != fn_hash_last_dflt)
                return 0;
        if ((state&NUD_VALID) ||
            (*last_idx<0 && order > fn_hash_last_dflt)) {
                *last_resort = fi;
                *last_idx = order;
        }
        return 1;
}

static void
fn_hash_select_default(struct fib_table *tb, const struct flowi *flp, struct fib_result *res)
{
        int order, last_idx;
        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);
        for (f = fz->fz_hash[0]; f; f = f->fn_next) {
                struct fib_info *next_fi = FIB_INFO(f);

                if ((f->fn_state&FN_S_ZOMBIE) ||
                    f->fn_scope != res->scope ||
                    f->fn_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;
                f->fn_state |= FN_S_ACCESSED;

                if (fi == NULL) {
                        if (next_fi != res->fi)
                                break;
                } else if (!fib_detect_death(fi, order, &last_resort, &last_idx)) {
                        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)) {
                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);
}

#define FIB_SCAN(f, fp) \
for ( ; ((f) = *(fp)) != NULL; (fp) = &(f)->fn_next)

#define FIB_SCAN_KEY(f, fp, key) \
for ( ; ((f) = *(fp)) != NULL && fn_key_eq((f)->fn_key, (key)); (fp) = &(f)->fn_next)

#ifndef CONFIG_IP_ROUTE_TOS
#define FIB_SCAN_TOS(f, fp, key, tos) FIB_SCAN_KEY(f, fp, key)
#else
#define FIB_SCAN_TOS(f, fp, key, tos) \
for ( ; ((f) = *(fp)) != NULL && fn_key_eq((f)->fn_key, (key)) && \
     (f)->fn_tos == (tos) ; (fp) = &(f)->fn_next)
#endif


static void rtmsg_fib(int, struct fib_node*, int, int,
                      struct nlmsghdr *n,
                      struct netlink_skb_parms *);

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, **fp, **del_fp;
        struct fn_zone *fz;
        struct fib_info *fi;

        int z = r->rtm_dst_len;
        int type = r->rtm_type;
#ifdef CONFIG_IP_ROUTE_TOS
        u8 tos = r->rtm_tos;
#endif
        fn_key_t key;
        int err;

FTprint("tb(%d)_insert: %d %08x/%d %d %08x\n", tb->tb_id, r->rtm_type, rta->rta_dst ?
*(u32*)rta->rta_dst : 0, z, rta->rta_oif ? *rta->rta_oif : -1,
rta->rta_prefsrc ? *(u32*)rta->rta_prefsrc : 0);
        if (z > 32)
                return -EINVAL;
        fz = table->fn_zones[z];
        if (!fz && !(fz = fn_new_zone(table, z)))
                return -ENOBUFS;

        fz_key_0(key);
        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);

        fp = fz_chain_p(key, fz);


        /*
         * Scan list to find the first route with the same destination
         */
        FIB_SCAN(f, fp) {
                if (fn_key_leq(key,f->fn_key))
                        break;
        }

#ifdef CONFIG_IP_ROUTE_TOS
        /*
         * Find route with the same destination and tos.
         */
        FIB_SCAN_KEY(f, fp, key) {
                if (f->fn_tos <= tos)
                        break;
        }
#endif

        del_fp = NULL;

        if (f && (f->fn_state&FN_S_ZOMBIE) &&
#ifdef CONFIG_IP_ROUTE_TOS
            f->fn_tos == tos &&
#endif
            fn_key_eq(f->fn_key, key)) {
                del_fp = fp;
                fp = &f->fn_next;
                f = *fp;
                goto create;
        }

        FIB_SCAN_TOS(f, fp, key, tos) {
                if (fi->fib_priority <= FIB_INFO(f)->fib_priority)
                        break;
        }

        /* Now f==*fp points to the first node with the same
           keys [prefix,tos,priority], if such key already
           exists or to the node, before which we will insert new one.
         */

        if (f && 
#ifdef CONFIG_IP_ROUTE_TOS
            f->fn_tos == tos &&
#endif
            fn_key_eq(f->fn_key, key) &&
            fi->fib_priority == FIB_INFO(f)->fib_priority) {
                struct fib_node **ins_fp;

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

                if (n->nlmsg_flags&NLM_F_REPLACE) {
                        del_fp = fp;
                        fp = &f->fn_next;
                        f = *fp;
                        goto replace;
                }

                ins_fp = fp;
                err = -EEXIST;

                FIB_SCAN_TOS(f, fp, key, tos) {
                        if (fi->fib_priority != FIB_INFO(f)->fib_priority)
                                break;
                        if (f->fn_type == type && f->fn_scope == r->rtm_scope
                            && FIB_INFO(f) == fi)
                                goto out;
                }

                if (!(n->nlmsg_flags&NLM_F_APPEND)) {
                        fp = ins_fp;
                        f = *fp;
                }
        }

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

replace:
        err = -ENOBUFS;
        new_f = kmem_cache_alloc(fn_hash_kmem, SLAB_KERNEL);
        if (new_f == NULL)
                goto out;

        memset(new_f, 0, sizeof(struct fib_node));

        new_f->fn_key = key;
#ifdef CONFIG_IP_ROUTE_TOS
        new_f->fn_tos = tos;
#endif
        new_f->fn_type = type;
        new_f->fn_scope = r->rtm_scope;
        FIB_INFO(new_f) = fi;

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

        new_f->fn_next = f;
        write_lock_bh(&fib_hash_lock);
        *fp = new_f;
        write_unlock_bh(&fib_hash_lock);
        fz->fz_nent++;

        if (del_fp) {
                f = *del_fp;
                /* Unlink replaced node */
                write_lock_bh(&fib_hash_lock);
                *del_fp = f->fn_next;
                write_unlock_bh(&fib_hash_lock);

                if (!(f->fn_state&FN_S_ZOMBIE))
                        rtmsg_fib(RTM_DELROUTE, f, z, tb->tb_id, n, req);
                if (f->fn_state&FN_S_ACCESSED)
                        rt_cache_flush(-1);
                fn_free_node(f);
                fz->fz_nent--;
        } else {
                rt_cache_flush(-1);
        }
        rtmsg_fib(RTM_NEWROUTE, new_f, z, tb->tb_id, n, req);
        return 0;

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 **fp, **del_fp, *f;
        int z = r->rtm_dst_len;
        struct fn_zone *fz;
        fn_key_t key;
        int matched;
#ifdef CONFIG_IP_ROUTE_TOS
        u8 tos = r->rtm_tos;
#endif

FTprint("tb(%d)_delete: %d %08x/%d %d\n", tb->tb_id, r->rtm_type, rta->rta_dst ?
       *(u32*)rta->rta_dst : 0, z, rta->rta_oif ? *rta->rta_oif : -1);
        if (z > 32)
                return -EINVAL;
        if ((fz  = table->fn_zones[z]) == NULL)
                return -ESRCH;

        fz_key_0(key);
        if (rta->rta_dst) {
                u32 dst;
                memcpy(&dst, rta->rta_dst, 4);
                if (dst & ~FZ_MASK(fz))
                        return -EINVAL;
                key = fz_key(dst, fz);
        }

        fp = fz_chain_p(key, fz);


        FIB_SCAN(f, fp) {
                if (fn_key_eq(f->fn_key, key))
                        break;
                if (fn_key_leq(key, f->fn_key)) {
                        return -ESRCH;
                }
        }
#ifdef CONFIG_IP_ROUTE_TOS
        FIB_SCAN_KEY(f, fp, key) {
                if (f->fn_tos == tos)
                        break;
        }
#endif

        matched = 0;
        del_fp = NULL;
        FIB_SCAN_TOS(f, fp, key, tos) {
                struct fib_info * fi = FIB_INFO(f);

                if (f->fn_state&FN_S_ZOMBIE) {
                        return -ESRCH;
                }
                matched++;

                if (del_fp == NULL &&
                    (!r->rtm_type || f->fn_type == r->rtm_type) &&
                    (r->rtm_scope == RT_SCOPE_NOWHERE || f->fn_scope == r->rtm_scope) &&
                    (!r->rtm_protocol || fi->fib_protocol == r->rtm_protocol) &&
                    fib_nh_match(r, n, rta, fi) == 0)
                        del_fp = fp;
        }

        if (del_fp) {
                f = *del_fp;
                rtmsg_fib(RTM_DELROUTE, f, z, tb->tb_id, n, req);

                if (matched != 1) {
                        write_lock_bh(&fib_hash_lock);
                        *del_fp = f->fn_next;
                        write_unlock_bh(&fib_hash_lock);

                        if (f->fn_state&FN_S_ACCESSED)
                                rt_cache_flush(-1);
                        fn_free_node(f);
                        fz->fz_nent--;
                } else {
                        f->fn_state |= FN_S_ZOMBIE;
                        if (f->fn_state&FN_S_ACCESSED) {
                                f->fn_state &= ~FN_S_ACCESSED;
                                rt_cache_flush(-1);
                        }
                        if (++fib_hash_zombies > 128)
                                fib_flush();
                }

                return 0;
        }
        return -ESRCH;
}

static __inline__ int
fn_flush_list(struct fib_node ** fp, int z, struct fn_hash *table)
{
        int found = 0;
        struct fib_node *f;

        while ((f = *fp) != NULL) {
                struct fib_info *fi = FIB_INFO(f);

                if (fi && ((f->fn_state&FN_S_ZOMBIE) || (fi->fib_flags&RTNH_F_DEAD))) {
                        write_lock_bh(&fib_hash_lock);
                        *fp = f->fn_next;
                        write_unlock_bh(&fib_hash_lock);

                        fn_free_node(f);
                        found++;
                        continue;
                }
                fp = &f->fn_next;
        }
        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;

        fib_hash_zombies = 0;
        for (fz = table->fn_zone_list; fz; fz = fz->fz_next) {
                int i;
                int tmp = 0;
                for (i=fz->fz_divisor-1; i>=0; i--)
                        tmp += fn_flush_list(&fz->fz_hash[i], fz->fz_order, table);
                fz->fz_nent -= tmp;
                found += tmp;
        }
        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 fib_node *f)
{
        int i, s_i;

        s_i = cb->args[3];
        for (i=0; f; i++, f=f->fn_next) {
                if (i < s_i) continue;
                if (f->fn_state&FN_S_ZOMBIE) continue;
                if (fib_dump_info(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
                                  RTM_NEWROUTE,
                                  tb->tb_id, (f->fn_state&FN_S_ZOMBIE) ? 0 : f->fn_type, f->fn_scope,
                                  &f->fn_key, fz->fz_order, f->fn_tos,
                                  f->fn_info) < 0) {
                        cb->args[3] = i;
                        return -1;
                }
        }
        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 || fz->fz_hash[h] == NULL)
                        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;
}

static void rtmsg_fib(int event, struct fib_node* f, int z, int tb_id,
                      struct nlmsghdr *n, struct netlink_skb_parms *req)
{
        struct sk_buff *skb;
        u32 pid = req ? req->pid : 0;
        int size = NLMSG_SPACE(sizeof(struct rtmsg)+256);

        skb = alloc_skb(size, GFP_KERNEL);
        if (!skb)
                return;

        if (fib_dump_info(skb, pid, n->nlmsg_seq, event, tb_id,
                          f->fn_type, f->fn_scope, &f->fn_key, z, f->fn_tos,
                          FIB_INFO(f)) < 0) {
                kfree_skb(skb);
                return;
        }
        NETLINK_CB(skb).dst_groups = RTMGRP_IPV4_ROUTE;
        if (n->nlmsg_flags&NLM_F_ECHO)
                atomic_inc(&skb->users);
        netlink_broadcast(rtnl, skb, pid, RTMGRP_IPV4_ROUTE, GFP_KERNEL);
        if (n->nlmsg_flags&NLM_F_ECHO)
                netlink_unicast(rtnl, skb, pid, MSG_DONTWAIT);
}

#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);

        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 fib_node **hash;
        struct fib_node *node;
};

static __inline__ struct fib_node *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   = NULL;
        iter->node   = NULL;

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

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

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

                for (iter->bucket = 0; iter->bucket < maxslot;
                     ++iter->bucket, ++iter->hash) {
                        iter->node = *iter->hash;

                        if (iter->node)
                                goto out;
                }
        }
out:
        return iter->node;
}

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

        if (iter->node)
                iter->node = iter->node->fn_next;

        if (iter->node)
                goto out;

        if (!iter->zone)
                goto out;

        for (;;) {
                int maxslot;

                maxslot = iter->zone->fz_divisor;

                while (++iter->bucket < maxslot) {
                        iter->node = *++iter->hash;

                        if (iter->node)
                                goto out;
                }

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

                if (!iter->zone)
                        goto out;
                
                iter->hash = iter->zone->fz_hash;
                iter->bucket = 0;
                iter->node = *iter->hash;
                if (iter->node)
                        break;
        }
out:
        return iter->node;
}

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_next(seq) : 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, int dead, 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;
        if (!dead)
                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_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;
        }

        f       = v;
        fi      = FIB_INFO(f);
        iter    = seq->private;
        prefix  = fz_prefix(f->fn_key, iter->zone);
        mask    = FZ_MASK(iter->zone);
        flags   = fib_flag_trans(f->fn_type, f->fn_state & FN_S_ZOMBIE,
                                 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 */