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/*

 * DECnet       An implementation of the DECnet protocol suite for the LINUX

 *              operating system.  DECnet is implemented using the  BSD Socket

 *              interface as the means of communication with the user level.

 *

 *              DECnet Routing Forwarding Information Base (Routing Tables)

 *

 * Author:      Steve Whitehouse <SteveW@ACM.org>

 *              Mostly copied from the IPv4 routing code

 *

 *

 * Changes:

 *

 */

#include <linux/string.h>

#include <linux/net.h>

#include <linux/socket.h>

#include <linux/sockios.h>

#include <linux/init.h>

#include <linux/skbuff.h>

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#include <linux/proc_fs.h>

#include <linux/netdevice.h>

#include <linux/timer.h>

#include <linux/spinlock.h>

#include <asm/atomic.h>

#include <asm/uaccess.h>

#include <linux/route.h> /* RTF_xxx */

#include <net/neighbour.h>

#include <net/netlink.h>

#include <net/dst.h>

#include <net/flow.h>

#include <net/fib_rules.h>

#include <net/dn.h>

#include <net/dn_route.h>

#include <net/dn_fib.h>

#include <net/dn_neigh.h>

#include <net/dn_dev.h>

struct dn_zone

{

        struct dn_zone          *dz_next;

        struct dn_fib_node      **dz_hash;

        int                     dz_nent;

        int                     dz_divisor;

        u32                     dz_hashmask;

#define DZ_HASHMASK(dz) ((dz)->dz_hashmask)

        int                     dz_order;

        __le16                  dz_mask;

#define DZ_MASK(dz)     ((dz)->dz_mask)

};

struct dn_hash

{

        struct dn_zone  *dh_zones[17];

        struct dn_zone  *dh_zone_list;

};

#define dz_key_0(key)           ((key).datum = 0)

#define dz_prefix(key,dz)       ((key).datum)

#define for_nexthops(fi) { int nhsel; const struct dn_fib_nh *nh;\

        for(nhsel = 0, nh = (fi)->fib_nh; nhsel < (fi)->fib_nhs; nh++, nhsel++)

#define endfor_nexthops(fi) }

#define DN_MAX_DIVISOR 1024

#define DN_S_ZOMBIE 1

#define DN_S_ACCESSED 2

#define DN_FIB_SCAN(f, fp) \

for( ; ((f) = *(fp)) != NULL; (fp) = &(f)->fn_next)

#define DN_FIB_SCAN_KEY(f, fp, key) \

for( ; ((f) = *(fp)) != NULL && dn_key_eq((f)->fn_key, (key)); (fp) = &(f)->fn_next)

#define RT_TABLE_MIN 1

#define DN_FIB_TABLE_HASHSZ 256

static struct hlist_head dn_fib_table_hash[DN_FIB_TABLE_HASHSZ];

static DEFINE_RWLOCK(dn_fib_tables_lock);

static struct kmem_cache *dn_hash_kmem __read_mostly;

static int dn_fib_hash_zombies;

static inline dn_fib_idx_t dn_hash(dn_fib_key_t key, struct dn_zone *dz)

{

        u16 h = dn_ntohs(key.datum)>>(16 - dz->dz_order);

        h ^= (h >> 10);

        h ^= (h >> 6);

        h &= DZ_HASHMASK(dz);

        return *(dn_fib_idx_t *)&h;

}

static inline dn_fib_key_t dz_key(__le16 dst, struct dn_zone *dz)

{

        dn_fib_key_t k;

        k.datum = dst & DZ_MASK(dz);

        return k;

}

static inline struct dn_fib_node **dn_chain_p(dn_fib_key_t key, struct dn_zone *dz)

{

        return &dz->dz_hash[dn_hash(key, dz).datum];

}

static inline struct dn_fib_node *dz_chain(dn_fib_key_t key, struct dn_zone *dz)

{

        return dz->dz_hash[dn_hash(key, dz).datum];

}

static inline int dn_key_eq(dn_fib_key_t a, dn_fib_key_t b)

{

        return a.datum == b.datum;

}

static inline int dn_key_leq(dn_fib_key_t a, dn_fib_key_t b)

{

        return a.datum <= b.datum;

}

static inline void dn_rebuild_zone(struct dn_zone *dz,

                                   struct dn_fib_node **old_ht,

                                   int old_divisor)

{

        int i;

        struct dn_fib_node *f, **fp, *next;

        for(i = 0; i < old_divisor; i++) {

                for(f = old_ht[i]; f; f = f->fn_next) {

                        next = f->fn_next;

                        for(fp = dn_chain_p(f->fn_key, dz);

                                *fp && dn_key_leq((*fp)->fn_key, f->fn_key);

                                fp = &(*fp)->fn_next)

                                /* NOTHING */;

                        f->fn_next = *fp;

                        *fp = f;

                }

        }

}

static void dn_rehash_zone(struct dn_zone *dz)

{

        struct dn_fib_node **ht, **old_ht;

        int old_divisor, new_divisor;

        u32 new_hashmask;

        old_divisor = dz->dz_divisor;

        switch(old_divisor) {

                case 16:

                        new_divisor = 256;

                        new_hashmask = 0xFF;

                        break;

                default:

                        printk(KERN_DEBUG "DECnet: dn_rehash_zone: BUG! %d\n", old_divisor);

                case 256:

                        new_divisor = 1024;

                        new_hashmask = 0x3FF;

                        break;

        }

        ht = kcalloc(new_divisor, sizeof(struct dn_fib_node*), GFP_KERNEL);

        if (ht == NULL)

                return;

        write_lock_bh(&dn_fib_tables_lock);

        old_ht = dz->dz_hash;

        dz->dz_hash = ht;

        dz->dz_hashmask = new_hashmask;

        dz->dz_divisor = new_divisor;

        dn_rebuild_zone(dz, old_ht, old_divisor);

        write_unlock_bh(&dn_fib_tables_lock);

        kfree(old_ht);

}

static void dn_free_node(struct dn_fib_node *f)

{

        dn_fib_release_info(DN_FIB_INFO(f));

        kmem_cache_free(dn_hash_kmem, f);

}

static struct dn_zone *dn_new_zone(struct dn_hash *table, int z)

{

        int i;

        struct dn_zone *dz = kzalloc(sizeof(struct dn_zone), GFP_KERNEL);

        if (!dz)

                return NULL;

        if (z) {

                dz->dz_divisor = 16;

                dz->dz_hashmask = 0x0F;

        } else {

                dz->dz_divisor = 1;

                dz->dz_hashmask = 0;

        }

        dz->dz_hash = kcalloc(dz->dz_divisor, sizeof(struct dn_fib_node *), GFP_KERNEL);

        if (!dz->dz_hash) {

                kfree(dz);

                return NULL;

        }

        dz->dz_order = z;

        dz->dz_mask = dnet_make_mask(z);

        for(i = z + 1; i <= 16; i++)

                if (table->dh_zones[i])

                        break;

        write_lock_bh(&dn_fib_tables_lock);

        if (i>16) {

                dz->dz_next = table->dh_zone_list;

                table->dh_zone_list = dz;

        } else {

                dz->dz_next = table->dh_zones[i]->dz_next;

                table->dh_zones[i]->dz_next = dz;

        }

        table->dh_zones[z] = dz;

        write_unlock_bh(&dn_fib_tables_lock);

        return dz;

}

static int dn_fib_nh_match(struct rtmsg *r, struct nlmsghdr *nlh, struct dn_kern_rta *rta, struct dn_fib_info *fi)

{

        struct rtnexthop *nhp;

        int nhlen;

        if (rta->rta_priority && *rta->rta_priority != fi->fib_priority)

                return 1;

        if (rta->rta_oif || rta->rta_gw) {

                if ((!rta->rta_oif || *rta->rta_oif == fi->fib_nh->nh_oif) &&

                    (!rta->rta_gw  || memcmp(rta->rta_gw, &fi->fib_nh->nh_gw, 2) == 0))

                        return 0;

                return 1;

        }

        if (rta->rta_mp == NULL)

                return 0;

        nhp = RTA_DATA(rta->rta_mp);

        nhlen = RTA_PAYLOAD(rta->rta_mp);

        for_nexthops(fi) {

                int attrlen = nhlen - sizeof(struct rtnexthop);

                __le16 gw;

                if (attrlen < 0 || (nhlen -= nhp->rtnh_len) < 0)

                        return -EINVAL;

                if (nhp->rtnh_ifindex && nhp->rtnh_ifindex != nh->nh_oif)

                        return 1;

                if (attrlen) {

                        gw = dn_fib_get_attr16(RTNH_DATA(nhp), attrlen, RTA_GATEWAY);

                        if (gw && gw != nh->nh_gw)

                                return 1;

                }

                nhp = RTNH_NEXT(nhp);

        } endfor_nexthops(fi);

        return 0;

}

static inline size_t dn_fib_nlmsg_size(struct dn_fib_info *fi)

{

        size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))

                         + nla_total_size(4) /* RTA_TABLE */

                         + nla_total_size(2) /* RTA_DST */

                         + nla_total_size(4); /* RTA_PRIORITY */

        /* space for nested metrics */

        payload += nla_total_size((RTAX_MAX * nla_total_size(4)));

        if (fi->fib_nhs) {

                /* Also handles the special case fib_nhs == 1 */

                /* each nexthop is packed in an attribute */

                size_t nhsize = nla_total_size(sizeof(struct rtnexthop));

                /* may contain a gateway attribute */

                nhsize += nla_total_size(4);

                /* all nexthops are packed in a nested attribute */

                payload += nla_total_size(fi->fib_nhs * nhsize);

        }

        return payload;

}

static int dn_fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,

                        u32 tb_id, u8 type, u8 scope, void *dst, int dst_len,

                        struct dn_fib_info *fi, unsigned int flags)

{

        struct rtmsg *rtm;

        struct nlmsghdr *nlh;

        unsigned char *b = skb_tail_pointer(skb);

        nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*rtm), flags);

        rtm = NLMSG_DATA(nlh);

        rtm->rtm_family = AF_DECnet;

        rtm->rtm_dst_len = dst_len;

        rtm->rtm_src_len = 0;

        rtm->rtm_tos = 0;

        rtm->rtm_table = tb_id;

        RTA_PUT_U32(skb, RTA_TABLE, tb_id);

        rtm->rtm_flags = fi->fib_flags;

        rtm->rtm_scope = scope;

        rtm->rtm_type  = type;

        if (rtm->rtm_dst_len)

                RTA_PUT(skb, RTA_DST, 2, dst);

        rtm->rtm_protocol = fi->fib_protocol;

        if (fi->fib_priority)

                RTA_PUT(skb, RTA_PRIORITY, 4, &fi->fib_priority);

        if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)

                goto rtattr_failure;

        if (fi->fib_nhs == 1) {

                if (fi->fib_nh->nh_gw)

                        RTA_PUT(skb, RTA_GATEWAY, 2, &fi->fib_nh->nh_gw);

                if (fi->fib_nh->nh_oif)

                        RTA_PUT(skb, RTA_OIF, sizeof(int), &fi->fib_nh->nh_oif);

        }

        if (fi->fib_nhs > 1) {

                struct rtnexthop *nhp;

                struct rtattr *mp_head;

                if (skb_tailroom(skb) <= RTA_SPACE(0))

                        goto rtattr_failure;

                mp_head = (struct rtattr *)skb_put(skb, RTA_SPACE(0));

                for_nexthops(fi) {

                        if (skb_tailroom(skb) < RTA_ALIGN(RTA_ALIGN(sizeof(*nhp)) + 4))

                                goto rtattr_failure;

                        nhp = (struct rtnexthop *)skb_put(skb, RTA_ALIGN(sizeof(*nhp)));

                        nhp->rtnh_flags = nh->nh_flags & 0xFF;

                        nhp->rtnh_hops = nh->nh_weight - 1;

                        nhp->rtnh_ifindex = nh->nh_oif;

                        if (nh->nh_gw)

                                RTA_PUT(skb, RTA_GATEWAY, 2, &nh->nh_gw);

                        nhp->rtnh_len = skb_tail_pointer(skb) - (unsigned char *)nhp;

                } endfor_nexthops(fi);

                mp_head->rta_type = RTA_MULTIPATH;

                mp_head->rta_len = skb_tail_pointer(skb) - (u8 *)mp_head;

        }

        nlh->nlmsg_len = skb_tail_pointer(skb) - b;

        return skb->len;

nlmsg_failure:

rtattr_failure:

        nlmsg_trim(skb, b);

        return -EMSGSIZE;

}

static void dn_rtmsg_fib(int event, struct dn_fib_node *f, int z, u32 tb_id,

                        struct nlmsghdr *nlh, struct netlink_skb_parms *req)

{

        struct sk_buff *skb;

        u32 pid = req ? req->pid : 0;

        int err = -ENOBUFS;

        skb = nlmsg_new(dn_fib_nlmsg_size(DN_FIB_INFO(f)), GFP_KERNEL);

        if (skb == NULL)

                goto errout;

        err = dn_fib_dump_info(skb, pid, nlh->nlmsg_seq, event, tb_id,

                               f->fn_type, f->fn_scope, &f->fn_key, z,

                               DN_FIB_INFO(f), 0);

        if (err < 0) {

                /* -EMSGSIZE implies BUG in dn_fib_nlmsg_size() */

                WARN_ON(err == -EMSGSIZE);

                kfree_skb(skb);

                goto errout;

        }

        err = rtnl_notify(skb, pid, RTNLGRP_DECnet_ROUTE, nlh, GFP_KERNEL);

errout:

        if (err < 0)

                rtnl_set_sk_err(RTNLGRP_DECnet_ROUTE, err);

}

static __inline__ int dn_hash_dump_bucket(struct sk_buff *skb,

                                struct netlink_callback *cb,

                                struct dn_fib_table *tb,

                                struct dn_zone *dz,

                                struct dn_fib_node *f)

{

        int i, s_i;

        s_i = cb->args[4];

        for(i = 0; f; i++, f = f->fn_next) {

                if (i < s_i)

                        continue;

                if (f->fn_state & DN_S_ZOMBIE)

                        continue;

                if (dn_fib_dump_info(skb, NETLINK_CB(cb->skb).pid,

                                cb->nlh->nlmsg_seq,

                                RTM_NEWROUTE,

                                tb->n,

                                (f->fn_state & DN_S_ZOMBIE) ? 0 : f->fn_type,

                                f->fn_scope, &f->fn_key, dz->dz_order,

                                f->fn_info, NLM_F_MULTI) < 0) {

                        cb->args[4] = i;

                        return -1;

                }

        }

        cb->args[4] = i;

        return skb->len;

}

static __inline__ int dn_hash_dump_zone(struct sk_buff *skb,

                                struct netlink_callback *cb,

                                struct dn_fib_table *tb,

                                struct dn_zone *dz)

{

        int h, s_h;

        s_h = cb->args[3];

        for(h = 0; h < dz->dz_divisor; h++) {

                if (h < s_h)

                        continue;

                if (h > s_h)

                        memset(&cb->args[4], 0, sizeof(cb->args) - 4*sizeof(cb->args[0]));

                if (dz->dz_hash == NULL || dz->dz_hash[h] == NULL)

                        continue;

                if (dn_hash_dump_bucket(skb, cb, tb, dz, dz->dz_hash[h]) < 0) {

                        cb->args[3] = h;

                        return -1;

                }

        }

        cb->args[3] = h;

        return skb->len;

}

static int dn_fib_table_dump(struct dn_fib_table *tb, struct sk_buff *skb,

                                struct netlink_callback *cb)

{

        int m, s_m;

        struct dn_zone *dz;

        struct dn_hash *table = (struct dn_hash *)tb->data;

        s_m = cb->args[2];

        read_lock(&dn_fib_tables_lock);

        for(dz = table->dh_zone_list, m = 0; dz; dz = dz->dz_next, m++) {

                if (m < s_m)

                        continue;

                if (m > s_m)

                        memset(&cb->args[3], 0, sizeof(cb->args) - 3*sizeof(cb->args[0]));

                if (dn_hash_dump_zone(skb, cb, tb, dz) < 0) {

                        cb->args[2] = m;

                        read_unlock(&dn_fib_tables_lock);

                        return -1;

                }

        }

        read_unlock(&dn_fib_tables_lock);

        cb->args[2] = m;

        return skb->len;

}

int dn_fib_dump(struct sk_buff *skb, struct netlink_callback *cb)

{

        unsigned int h, s_h;

        unsigned int e = 0, s_e;

        struct dn_fib_table *tb;

        struct hlist_node *node;

        int dumped = 0;

        if (NLMSG_PAYLOAD(cb->nlh, 0) >= sizeof(struct rtmsg) &&

                ((struct rtmsg *)NLMSG_DATA(cb->nlh))->rtm_flags&RTM_F_CLONED)

                        return dn_cache_dump(skb, cb);

        s_h = cb->args[0];

        s_e = cb->args[1];

        for (h = s_h; h < DN_FIB_TABLE_HASHSZ; h++, s_h = 0) {

                e = 0;

                hlist_for_each_entry(tb, node, &dn_fib_table_hash[h], hlist) {

                        if (e < s_e)

                                goto next;

                        if (dumped)

                                memset(&cb->args[2], 0, sizeof(cb->args) -

                                                 2 * sizeof(cb->args[0]));

                        if (tb->dump(tb, skb, cb) < 0)

                                goto out;

                        dumped = 1;

next:

                        e++;

                }

        }

out:

        cb->args[1] = e;

        cb->args[0] = h;

        return skb->len;

}

static int dn_fib_table_insert(struct dn_fib_table *tb, struct rtmsg *r, struct dn_kern_rta *rta, struct nlmsghdr *n, struct netlink_skb_parms *req)

{

        struct dn_hash *table = (struct dn_hash *)tb->data;

        struct dn_fib_node *new_f, *f, **fp, **del_fp;

        struct dn_zone *dz;

        struct dn_fib_info *fi;

        int z = r->rtm_dst_len;

        int type = r->rtm_type;

        dn_fib_key_t key;

        int err;

        if (z > 16)

                return -EINVAL;

        dz = table->dh_zones[z];

        if (!dz && !(dz = dn_new_zone(table, z)))

                return -ENOBUFS;

        dz_key_0(key);

        if (rta->rta_dst) {

                __le16 dst;

                memcpy(&dst, rta->rta_dst, 2);

                if (dst & ~DZ_MASK(dz))

                        return -EINVAL;

                key = dz_key(dst, dz);

        }

        if ((fi = dn_fib_create_info(r, rta, n, &err)) == NULL)

                return err;

        if (dz->dz_nent > (dz->dz_divisor << 2) &&

                        dz->dz_divisor > DN_MAX_DIVISOR &&

                        (z==16 || (1<<z) > dz->dz_divisor))

                dn_rehash_zone(dz);

        fp = dn_chain_p(key, dz);

        DN_FIB_SCAN(f, fp) {

                if (dn_key_leq(key, f->fn_key))

                        break;

        }

        del_fp = NULL;

        if (f && (f->fn_state & DN_S_ZOMBIE) &&

                        dn_key_eq(f->fn_key, key)) {

                del_fp = fp;

                fp = &f->fn_next;

                f = *fp;

                goto create;

        }

        DN_FIB_SCAN_KEY(f, fp, key) {

                if (fi->fib_priority <= DN_FIB_INFO(f)->fib_priority)

                        break;

        }

        if (f && dn_key_eq(f->fn_key, key) &&

                        fi->fib_priority == DN_FIB_INFO(f)->fib_priority) {

                struct dn_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;

                DN_FIB_SCAN_KEY(f, fp, key) {

                        if (fi->fib_priority != DN_FIB_INFO(f)->fib_priority)

                                break;

                        if (f->fn_type == type && f->fn_scope == r->rtm_scope

                                        && DN_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_zalloc(dn_hash_kmem, GFP_KERNEL);

        if (new_f == NULL)

                goto out;

        new_f->fn_key = key;

        new_f->fn_type = type;

        new_f->fn_scope = r->rtm_scope;

        DN_FIB_INFO(new_f) = fi;

        new_f->fn_next = f;

        write_lock_bh(&dn_fib_tables_lock);

        *fp = new_f;

        write_unlock_bh(&dn_fib_tables_lock);

        dz->dz_nent++;

        if (del_fp) {

                f = *del_fp;

                write_lock_bh(&dn_fib_tables_lock);

                *del_fp = f->fn_next;

                write_unlock_bh(&dn_fib_tables_lock);

                if (!(f->fn_state & DN_S_ZOMBIE))

                        dn_rtmsg_fib(RTM_DELROUTE, f, z, tb->n, n, req);