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/* net/atm/clip.c - RFC1577 Classical IP over ATM */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#include <linux/string.h>

#include <linux/errno.h>

#include <linux/kernel.h> /* for UINT_MAX */

#include <linux/module.h>

#include <linux/init.h>

#include <linux/netdevice.h>

#include <linux/skbuff.h>

#include <linux/wait.h>

#include <linux/timer.h>

#include <linux/if_arp.h> /* for some manifest constants */

#include <linux/notifier.h>

#include <linux/atm.h>

#include <linux/atmdev.h>

#include <linux/atmclip.h>

#include <linux/atmarp.h>

#include <linux/capability.h>

#include <linux/ip.h> /* for net/route.h */

#include <linux/in.h> /* for struct sockaddr_in */

#include <linux/if.h> /* for IFF_UP */

#include <linux/inetdevice.h>

#include <linux/bitops.h>

#include <linux/poison.h>

#include <linux/proc_fs.h>

#include <linux/seq_file.h>

#include <linux/rcupdate.h>

#include <linux/jhash.h>

#include <net/route.h> /* for struct rtable and routing */

#include <net/icmp.h> /* icmp_send */

#include <asm/param.h> /* for HZ */

#include <asm/byteorder.h> /* for htons etc. */

#include <asm/system.h> /* save/restore_flags */

#include <asm/uaccess.h>

#include <asm/atomic.h>

#include "common.h"

#include "resources.h"

#include <net/atmclip.h>

static struct net_device *clip_devs;

static struct atm_vcc *atmarpd;

static struct neigh_table clip_tbl;

static struct timer_list idle_timer;

static int to_atmarpd(enum atmarp_ctrl_type type, int itf, __be32 ip)

{

        struct sock *sk;

        struct atmarp_ctrl *ctrl;

        struct sk_buff *skb;

        pr_debug("to_atmarpd(%d)\n", type);

        if (!atmarpd)

                return -EUNATCH;

        skb = alloc_skb(sizeof(struct atmarp_ctrl),GFP_ATOMIC);

        if (!skb)

                return -ENOMEM;

        ctrl = (struct atmarp_ctrl *) skb_put(skb,sizeof(struct atmarp_ctrl));

        ctrl->type = type;

        ctrl->itf_num = itf;

        ctrl->ip = ip;

        atm_force_charge(atmarpd, skb->truesize);

        sk = sk_atm(atmarpd);

        skb_queue_tail(&sk->sk_receive_queue, skb);

        sk->sk_data_ready(sk, skb->len);

        return 0;

}

static void link_vcc(struct clip_vcc *clip_vcc, struct atmarp_entry *entry)

{

        pr_debug("link_vcc %p to entry %p (neigh %p)\n", clip_vcc, entry,

                entry->neigh);

        clip_vcc->entry = entry;

        clip_vcc->xoff = 0;      /* @@@ may overrun buffer by one packet */

        clip_vcc->next = entry->vccs;

        entry->vccs = clip_vcc;

        entry->neigh->used = jiffies;

}

static void unlink_clip_vcc(struct clip_vcc *clip_vcc)

{

        struct atmarp_entry *entry = clip_vcc->entry;

        struct clip_vcc **walk;

        if (!entry) {

                printk(KERN_CRIT "!clip_vcc->entry (clip_vcc %p)\n", clip_vcc);

                return;

        }

        netif_tx_lock_bh(entry->neigh->dev);    /* block clip_start_xmit() */

        entry->neigh->used = jiffies;

        for (walk = &entry->vccs; *walk; walk = &(*walk)->next)

                if (*walk == clip_vcc) {

                        int error;

                        *walk = clip_vcc->next; /* atomic */

                        clip_vcc->entry = NULL;

                        if (clip_vcc->xoff)

                                netif_wake_queue(entry->neigh->dev);

                        if (entry->vccs)

                                goto out;

                        entry->expires = jiffies - 1;

                        /* force resolution or expiration */

                        error = neigh_update(entry->neigh, NULL, NUD_NONE,

                                             NEIGH_UPDATE_F_ADMIN);

                        if (error)

                                printk(KERN_CRIT "unlink_clip_vcc: "

                                       "neigh_update failed with %d\n", error);

                        goto out;

                }

        printk(KERN_CRIT "ATMARP: unlink_clip_vcc failed (entry %p, vcc "

               "0x%p)\n", entry, clip_vcc);

      out:

        netif_tx_unlock_bh(entry->neigh->dev);

}

/* The neighbour entry n->lock is held. */

static int neigh_check_cb(struct neighbour *n)

{

        struct atmarp_entry *entry = NEIGH2ENTRY(n);

        struct clip_vcc *cv;

        for (cv = entry->vccs; cv; cv = cv->next) {

                unsigned long exp = cv->last_use + cv->idle_timeout;

                if (cv->idle_timeout && time_after(jiffies, exp)) {

                        pr_debug("releasing vcc %p->%p of entry %p\n",

                                cv, cv->vcc, entry);

                        vcc_release_async(cv->vcc, -ETIMEDOUT);

                }

        }

        if (entry->vccs || time_before(jiffies, entry->expires))

                return 0;

        if (atomic_read(&n->refcnt) > 1) {

                struct sk_buff *skb;

                pr_debug("destruction postponed with ref %d\n",

                        atomic_read(&n->refcnt));

                while ((skb = skb_dequeue(&n->arp_queue)) != NULL)

                        dev_kfree_skb(skb);

                return 0;

        }

        pr_debug("expired neigh %p\n", n);

        return 1;

}

static void idle_timer_check(unsigned long dummy)

{

        write_lock(&clip_tbl.lock);

        __neigh_for_each_release(&clip_tbl, neigh_check_cb);

        mod_timer(&idle_timer, jiffies + CLIP_CHECK_INTERVAL * HZ);

        write_unlock(&clip_tbl.lock);

}

static int clip_arp_rcv(struct sk_buff *skb)

{

        struct atm_vcc *vcc;

        pr_debug("clip_arp_rcv\n");

        vcc = ATM_SKB(skb)->vcc;

        if (!vcc || !atm_charge(vcc, skb->truesize)) {

                dev_kfree_skb_any(skb);

                return 0;

        }

        pr_debug("pushing to %p\n", vcc);

        pr_debug("using %p\n", CLIP_VCC(vcc)->old_push);

        CLIP_VCC(vcc)->old_push(vcc, skb);

        return 0;

}

static const unsigned char llc_oui[] = {

        0xaa,   /* DSAP: non-ISO */

        0xaa,   /* SSAP: non-ISO */

        0x03,   /* Ctrl: Unnumbered Information Command PDU */

        0x00,   /* OUI: EtherType */

        0x00,

        0x00

};

static void clip_push(struct atm_vcc *vcc, struct sk_buff *skb)

{

        struct clip_vcc *clip_vcc = CLIP_VCC(vcc);

        pr_debug("clip push\n");

        if (!skb) {

                pr_debug("removing VCC %p\n", clip_vcc);

                if (clip_vcc->entry)

                        unlink_clip_vcc(clip_vcc);

                clip_vcc->old_push(vcc, NULL);  /* pass on the bad news */

                kfree(clip_vcc);

                return;

        }

        atm_return(vcc, skb->truesize);

        skb->dev = clip_vcc->entry ? clip_vcc->entry->neigh->dev : clip_devs;

        /* clip_vcc->entry == NULL if we don't have an IP address yet */

        if (!skb->dev) {

                dev_kfree_skb_any(skb);

                return;

        }

        ATM_SKB(skb)->vcc = vcc;

        skb_reset_mac_header(skb);

        if (!clip_vcc->encap

            || skb->len < RFC1483LLC_LEN

            || memcmp(skb->data, llc_oui, sizeof (llc_oui)))

                skb->protocol = htons(ETH_P_IP);

        else {

                skb->protocol = ((__be16 *) skb->data)[3];

                skb_pull(skb, RFC1483LLC_LEN);

                if (skb->protocol == htons(ETH_P_ARP)) {

                        PRIV(skb->dev)->stats.rx_packets++;

                        PRIV(skb->dev)->stats.rx_bytes += skb->len;

                        clip_arp_rcv(skb);

                        return;

                }

        }

        clip_vcc->last_use = jiffies;

        PRIV(skb->dev)->stats.rx_packets++;

        PRIV(skb->dev)->stats.rx_bytes += skb->len;

        memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));

        netif_rx(skb);

}

/*

 * Note: these spinlocks _must_not_ block on non-SMP. The only goal is that

 * clip_pop is atomic with respect to the critical section in clip_start_xmit.

 */

static void clip_pop(struct atm_vcc *vcc, struct sk_buff *skb)

{

        struct clip_vcc *clip_vcc = CLIP_VCC(vcc);

        struct net_device *dev = skb->dev;

        int old;

        unsigned long flags;

        pr_debug("clip_pop(vcc %p)\n", vcc);

        clip_vcc->old_pop(vcc, skb);

        /* skb->dev == NULL in outbound ARP packets */

        if (!dev)

                return;

        spin_lock_irqsave(&PRIV(dev)->xoff_lock, flags);

        if (atm_may_send(vcc, 0)) {

                old = xchg(&clip_vcc->xoff, 0);

                if (old)

                        netif_wake_queue(dev);

        }

        spin_unlock_irqrestore(&PRIV(dev)->xoff_lock, flags);

}

static void clip_neigh_solicit(struct neighbour *neigh, struct sk_buff *skb)

{

        pr_debug("clip_neigh_solicit (neigh %p, skb %p)\n", neigh, skb);

        to_atmarpd(act_need, PRIV(neigh->dev)->number, NEIGH2ENTRY(neigh)->ip);

}

static void clip_neigh_error(struct neighbour *neigh, struct sk_buff *skb)

{

#ifndef CONFIG_ATM_CLIP_NO_ICMP

        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);

#endif

        kfree_skb(skb);

}

static struct neigh_ops clip_neigh_ops = {

        .family =               AF_INET,

        .solicit =              clip_neigh_solicit,

        .error_report =         clip_neigh_error,

        .output =               dev_queue_xmit,

        .connected_output =     dev_queue_xmit,

        .hh_output =            dev_queue_xmit,

        .queue_xmit =           dev_queue_xmit,

};

static int clip_constructor(struct neighbour *neigh)

{

        struct atmarp_entry *entry = NEIGH2ENTRY(neigh);

        struct net_device *dev = neigh->dev;

        struct in_device *in_dev;

        struct neigh_parms *parms;

        pr_debug("clip_constructor (neigh %p, entry %p)\n", neigh, entry);

        neigh->type = inet_addr_type(entry->ip);

        if (neigh->type != RTN_UNICAST)

                return -EINVAL;

        rcu_read_lock();

        in_dev = __in_dev_get_rcu(dev);

        if (!in_dev) {

                rcu_read_unlock();

                return -EINVAL;

        }

        parms = in_dev->arp_parms;

        __neigh_parms_put(neigh->parms);

        neigh->parms = neigh_parms_clone(parms);

        rcu_read_unlock();

        neigh->ops = &clip_neigh_ops;

        neigh->output = neigh->nud_state & NUD_VALID ?

            neigh->ops->connected_output : neigh->ops->output;

        entry->neigh = neigh;

        entry->vccs = NULL;

        entry->expires = jiffies - 1;

        return 0;

}

static u32 clip_hash(const void *pkey, const struct net_device *dev)

{

        return jhash_2words(*(u32 *) pkey, dev->ifindex, clip_tbl.hash_rnd);

}

static struct neigh_table clip_tbl = {

        .family         = AF_INET,

        .entry_size     = sizeof(struct neighbour)+sizeof(struct atmarp_entry),

        .key_len        = 4,

        .hash           = clip_hash,

        .constructor    = clip_constructor,

        .id             = "clip_arp_cache",

        /* parameters are copied from ARP ... */

        .parms = {

                .tbl                    = &clip_tbl,

                .base_reachable_time    = 30 * HZ,

                .retrans_time           = 1 * HZ,

                .gc_staletime           = 60 * HZ,

                .reachable_time         = 30 * HZ,

                .delay_probe_time       = 5 * HZ,

                .queue_len              = 3,

                .ucast_probes           = 3,

                .mcast_probes           = 3,

                .anycast_delay          = 1 * HZ,

                .proxy_delay            = (8 * HZ) / 10,

                .proxy_qlen             = 64,

                .locktime               = 1 * HZ,

        },

        .gc_interval    = 30 * HZ,

        .gc_thresh1     = 128,

        .gc_thresh2     = 512,

        .gc_thresh3     = 1024,

};

/* @@@ copy bh locking from arp.c -- need to bh-enable atm code before */

/*

 * We play with the resolve flag: 0 and 1 have the usual meaning, but -1 means

 * to allocate the neighbour entry but not to ask atmarpd for resolution. Also,

 * don't increment the usage count. This is used to create entries in

 * clip_setentry.

 */

static int clip_encap(struct atm_vcc *vcc, int mode)

{

        CLIP_VCC(vcc)->encap = mode;

        return 0;

}

static int clip_start_xmit(struct sk_buff *skb, struct net_device *dev)

{

        struct clip_priv *clip_priv = PRIV(dev);

        struct atmarp_entry *entry;

        struct atm_vcc *vcc;

        int old;

        unsigned long flags;

        pr_debug("clip_start_xmit (skb %p)\n", skb);

        if (!skb->dst) {

                printk(KERN_ERR "clip_start_xmit: skb->dst == NULL\n");

                dev_kfree_skb(skb);

                clip_priv->stats.tx_dropped++;

                return 0;

        }

        if (!skb->dst->neighbour) {

#if 0

                skb->dst->neighbour = clip_find_neighbour(skb->dst, 1);

                if (!skb->dst->neighbour) {

                        dev_kfree_skb(skb);     /* lost that one */

                        clip_priv->stats.tx_dropped++;

                        return 0;

                }

#endif

                printk(KERN_ERR "clip_start_xmit: NO NEIGHBOUR !\n");

                dev_kfree_skb(skb);

                clip_priv->stats.tx_dropped++;

                return 0;

        }

        entry = NEIGH2ENTRY(skb->dst->neighbour);

        if (!entry->vccs) {

                if (time_after(jiffies, entry->expires)) {

                        /* should be resolved */

                        entry->expires = jiffies + ATMARP_RETRY_DELAY * HZ;

                        to_atmarpd(act_need, PRIV(dev)->number, entry->ip);

                }

                if (entry->neigh->arp_queue.qlen < ATMARP_MAX_UNRES_PACKETS)

                        skb_queue_tail(&entry->neigh->arp_queue, skb);

                else {

                        dev_kfree_skb(skb);

                        clip_priv->stats.tx_dropped++;

                }

                return 0;

        }

        pr_debug("neigh %p, vccs %p\n", entry, entry->vccs);

        ATM_SKB(skb)->vcc = vcc = entry->vccs->vcc;

        pr_debug("using neighbour %p, vcc %p\n", skb->dst->neighbour, vcc);

        if (entry->vccs->encap) {

                void *here;

                here = skb_push(skb, RFC1483LLC_LEN);

                memcpy(here, llc_oui, sizeof(llc_oui));

                ((__be16 *) here)[3] = skb->protocol;

        }

        atomic_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);

        ATM_SKB(skb)->atm_options = vcc->atm_options;

        entry->vccs->last_use = jiffies;

        pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, vcc, vcc->dev);

        old = xchg(&entry->vccs->xoff, 1);      /* assume XOFF ... */

        if (old) {

                printk(KERN_WARNING "clip_start_xmit: XOFF->XOFF transition\n");

                return 0;

        }

        clip_priv->stats.tx_packets++;

        clip_priv->stats.tx_bytes += skb->len;

        vcc->send(vcc, skb);

        if (atm_may_send(vcc, 0)) {

                entry->vccs->xoff = 0;

                return 0;

        }

        spin_lock_irqsave(&clip_priv->xoff_lock, flags);

        netif_stop_queue(dev);  /* XOFF -> throttle immediately */

        barrier();

        if (!entry->vccs->xoff)

                netif_start_queue(dev);

        /* Oh, we just raced with clip_pop. netif_start_queue should be

           good enough, because nothing should really be asleep because

           of the brief netif_stop_queue. If this isn't true or if it

           changes, use netif_wake_queue instead. */

        spin_unlock_irqrestore(&clip_priv->xoff_lock, flags);

        return 0;

}

static struct net_device_stats *clip_get_stats(struct net_device *dev)

{

        return &PRIV(dev)->stats;

}

static int clip_mkip(struct atm_vcc *vcc, int timeout)

{

        struct clip_vcc *clip_vcc;

        struct sk_buff *skb;

        struct sk_buff_head *rq;

        unsigned long flags;

        if (!vcc->push)

                return -EBADFD;

        clip_vcc = kmalloc(sizeof(struct clip_vcc), GFP_KERNEL);

        if (!clip_vcc)

                return -ENOMEM;

        pr_debug("mkip clip_vcc %p vcc %p\n", clip_vcc, vcc);

        clip_vcc->vcc = vcc;

        vcc->user_back = clip_vcc;

        set_bit(ATM_VF_IS_CLIP, &vcc->flags);

        clip_vcc->entry = NULL;

        clip_vcc->xoff = 0;

        clip_vcc->encap = 1;

        clip_vcc->last_use = jiffies;

        clip_vcc->idle_timeout = timeout * HZ;

        clip_vcc->old_push = vcc->push;

        clip_vcc->old_pop = vcc->pop;

        vcc->push = clip_push;

        vcc->pop = clip_pop;

        rq = &sk_atm(vcc)->sk_receive_queue;

        spin_lock_irqsave(&rq->lock, flags);

        if (skb_queue_empty(rq)) {

                skb = NULL;

        } else {

                /* NULL terminate the list.  */

                rq->prev->next = NULL;

                skb = rq->next;

        }

        rq->prev = rq->next = (struct sk_buff *)rq;

        rq->qlen = 0;

        spin_unlock_irqrestore(&rq->lock, flags);

        /* re-process everything received between connection setup and MKIP */

        while (skb) {

                struct sk_buff *next = skb->next;

                skb->next = skb->prev = NULL;

                if (!clip_devs) {

                        atm_return(vcc, skb->truesize);

                        kfree_skb(skb);

                } else {

                        unsigned int len = skb->len;

                        skb_get(skb);

                        clip_push(vcc, skb);

                        PRIV(skb->dev)->stats.rx_packets--;

                        PRIV(skb->dev)->stats.rx_bytes -= len;

                        kfree_skb(skb);

                }

                skb = next;

        }

        return 0;

}

static int clip_setentry(struct atm_vcc *vcc, __be32 ip)

{

        struct neighbour *neigh;

        struct atmarp_entry *entry;

        int error;

        struct clip_vcc *clip_vcc;

        struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip, .tos = 1}} };

        struct rtable *rt;

        if (vcc->push != clip_push) {

                printk(KERN_WARNING "clip_setentry: non-CLIP VCC\n");

                return -EBADF;

        }

        clip_vcc = CLIP_VCC(vcc);

        if (!ip) {

                if (!clip_vcc->entry) {

                        printk(KERN_ERR "hiding hidden ATMARP entry\n");

                        return 0;

                }

                pr_debug("setentry: remove\n");

                unlink_clip_vcc(clip_vcc);

                return 0;

        }

        error = ip_route_output_key(&rt, &fl);

        if (error)

                return error;

        neigh = __neigh_lookup(&clip_tbl, &ip, rt->u.dst.dev, 1);

        ip_rt_put(rt);

        if (!neigh)

                return -ENOMEM;

        entry = NEIGH2ENTRY(neigh);

        if (entry != clip_vcc->entry) {

                if (!clip_vcc->entry)

                        pr_debug("setentry: add\n");

                else {

                        pr_debug("setentry: update\n");

                        unlink_clip_vcc(clip_vcc);

                }

                link_vcc(clip_vcc, entry);

        }

        error = neigh_update(neigh, llc_oui, NUD_PERMANENT,

                             NEIGH_UPDATE_F_OVERRIDE | NEIGH_UPDATE_F_ADMIN);

        neigh_release(neigh);

        return error;

}

static void clip_setup(struct net_device *dev)

{

        dev->hard_start_xmit = clip_start_xmit;

        /* sg_xmit ... */

        dev->get_stats = clip_get_stats;

        dev->type = ARPHRD_ATM;

        dev->hard_header_len = RFC1483LLC_LEN;

        dev->mtu = RFC1626_MTU;

        dev->tx_queue_len = 100;        /* "normal" queue (packets) */

        /* When using a "real" qdisc, the qdisc determines the queue */

        /* length. tx_queue_len is only used for the default case, */

        /* without any more elaborate queuing. 100 is a reasonable */

        /* compromise between decent burst-tolerance and protection */

        /* against memory hogs. */

}

static int clip_create(int number)

{

        struct net_device *dev;

        struct clip_priv *clip_priv;

        int error;

        if (number != -1) {

                for (dev = clip_devs; dev; dev = PRIV(dev)->next)

                        if (PRIV(dev)->number == number)

                                return -EEXIST;

        } else {

                number = 0;

                for (dev = clip_devs; dev; dev = PRIV(dev)->next)

                        if (PRIV(dev)->number >= number)

                                number = PRIV(dev)->number + 1;

        }

        dev = alloc_netdev(sizeof(struct clip_priv), "", clip_setup);

        if (!dev)

                return -ENOMEM;

        clip_priv = PRIV(dev);

        sprintf(dev->name, "atm%d", number);

        spin_lock_init(&clip_priv->xoff_lock);

        clip_priv->number = number;

        error = register_netdev(dev);

        if (error) {

                free_netdev(dev);

                return error;

        }

        clip_priv->next = clip_devs;

        clip_devs = dev;

        pr_debug("registered (net:%s)\n", dev->name);

        return number;

}

static int clip_device_event(struct notifier_block *this, unsigned long event,

                             void *arg)

{

        struct net_device *dev = arg;

        if (dev->nd_net != &init_net)

                return NOTIFY_DONE;

        if (event == NETDEV_UNREGISTER) {

                neigh_ifdown(&clip_tbl, dev);

                return NOTIFY_DONE;

        }

        /* ignore non-CLIP devices */

        if (dev->type != ARPHRD_ATM || dev->hard_start_xmit != clip_start_xmit)

                return NOTIFY_DONE;

        switch (event) {

        case NETDEV_UP:

                pr_debug("clip_device_event NETDEV_UP\n");