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

/* Written 1995-1999 by Werner Almesberger, EPFL LRC/ICA */


#include <linux/config.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/kernel.h> /* for UINT_MAX */
#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/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 <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 "tunable.h"
#include "resources.h"
#include "ipcommon.h"
#include <net/atmclip.h>


#if 0
#define DPRINTK(format,args...) printk(format,##args)
#else
#define DPRINTK(format,args...)
#endif


struct net_device *clip_devs = NULL;
struct atm_vcc *atmarpd = NULL;
static struct timer_list idle_timer;
static int start_timer = 1;


static int to_atmarpd(enum atmarp_ctrl_type type,int itf,unsigned long ip)
{
	struct atmarp_ctrl *ctrl;
	struct sk_buff *skb;

	DPRINTK("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);
	skb_queue_tail(&atmarpd->recvq,skb);
	wake_up(&atmarpd->sleep);
	return 0;
}


static void link_vcc(struct clip_vcc *clip_vcc,struct atmarp_entry *entry)
{
	DPRINTK("link_vcc %p to entry %p (neigh %p)\n",clip_vcc,entry,
	    entry->neigh);
	clip_vcc->entry = entry;
	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;
	}
	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 (entry->vccs) return;
			entry->expires = jiffies-1;
				/* force resolution or expiration */
			error = neigh_update(entry->neigh,NULL,NUD_NONE,0,0);
			if (error)
				printk(KERN_CRIT "unlink_clip_vcc: "
				    "neigh_update failed with %d\n",error);
			return;
		}
	printk(KERN_CRIT "ATMARP: unlink_clip_vcc failed (entry %p, vcc "
	  "0x%p)\n",entry,clip_vcc);
}


static void idle_timer_check(unsigned long dummy)
{
	int i;

	/*DPRINTK("idle_timer_check\n");*/
	write_lock(&clip_tbl.lock);
	for (i = 0; i <= NEIGH_HASHMASK; i++) {
		struct neighbour **np;

		for (np = &clip_tbl.hash_buckets[i]; *np;) {
			struct neighbour *n = *np;
			struct atmarp_entry *entry = NEIGH2ENTRY(n);
			struct clip_vcc *clip_vcc;

			for (clip_vcc = entry->vccs; clip_vcc;
			    clip_vcc = clip_vcc->next)
				if (clip_vcc->idle_timeout &&
				    time_after(jiffies, clip_vcc->last_use+
				    clip_vcc->idle_timeout)) {
					DPRINTK("releasing vcc %p->%p of "
					    "entry %p\n",clip_vcc,clip_vcc->vcc,
					    entry);
					atm_async_release_vcc(clip_vcc->vcc,
					    -ETIMEDOUT);
				}
			if (entry->vccs ||
			    time_before(jiffies, entry->expires)) {
				np = &n->next;
				continue;
			}
			if (atomic_read(&n->refcnt) > 1) {
				struct sk_buff *skb;

				DPRINTK("destruction postponed with ref %d\n",
				    atomic_read(&n->refcnt));
				while ((skb = skb_dequeue(&n->arp_queue)) !=
				     NULL) 
					dev_kfree_skb(skb);
				np = &n->next;
				continue;
			}
			*np = n->next;
			DPRINTK("expired neigh %p\n",n);
			n->dead = 1;
			neigh_release(n);
		}
	}
	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;

	DPRINTK("clip_arp_rcv\n");
	vcc = ATM_SKB(skb)->vcc;
	if (!vcc || !atm_charge(vcc,skb->truesize)) {
		kfree_skb(skb);
		return 0;
	}
	DPRINTK("pushing to %p\n",vcc);
	DPRINTK("using %p\n",CLIP_VCC(vcc)->old_push);
	CLIP_VCC(vcc)->old_push(vcc,skb);
	return 0;
}


void clip_push(struct atm_vcc *vcc,struct sk_buff *skb)
{
	struct clip_vcc *clip_vcc = CLIP_VCC(vcc);

	DPRINTK("clip push\n");
	if (!skb) {
		DPRINTK("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) {
		kfree_skb(skb);
		return;
	}
	ATM_SKB(skb)->vcc = vcc;
	skb->mac.raw = skb->data;
	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 = ((u16 *) 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;
	netif_rx(skb);
}


static void clip_neigh_destroy(struct neighbour *neigh)
{
	DPRINTK("clip_neigh_destroy (neigh %p)\n",neigh);
	if (NEIGH2ENTRY(neigh)->vccs)
		printk(KERN_CRIT "clip_neigh_destroy: vccs != NULL !!!\n");
	NEIGH2ENTRY(neigh)->vccs = (void *) 0xdeadbeef;
}


static void clip_neigh_solicit(struct neighbour *neigh,struct sk_buff *skb)
{
	DPRINTK("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 = {
	AF_INET,		/* family */
	clip_neigh_destroy,	/* destructor */
	clip_neigh_solicit,	/* solicit */
	clip_neigh_error,	/* error_report */
	dev_queue_xmit,		/* output */
	dev_queue_xmit,		/* connected_output */
	dev_queue_xmit,		/* hh_output */
	dev_queue_xmit		/* 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 = dev->ip_ptr;

	DPRINTK("clip_constructor (neigh %p, entry %p)\n",neigh,entry);
	if (!in_dev) return -EINVAL;
	neigh->type = inet_addr_type(entry->ip);
	if (neigh->type != RTN_UNICAST) return -EINVAL;
	if (in_dev->arp_parms) neigh->parms = in_dev->arp_parms;
	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)
{
	u32 hash_val;

	hash_val = *(u32*)pkey;
	hash_val ^= (hash_val>>16);
	hash_val ^= hash_val>>8;
	hash_val ^= hash_val>>3;
	hash_val = (hash_val^dev->ifindex)&NEIGH_HASHMASK;

	return hash_val;
}


struct neigh_table clip_tbl = {
	NULL,			/* next */
	AF_INET,		/* family */
	sizeof(struct neighbour)+sizeof(struct atmarp_entry), /* entry_size */
	4,			/* key_len */
	clip_hash,
	clip_constructor,	/* constructor */
	NULL,			/* pconstructor */
	NULL,			/* pdestructor */
	NULL,			/* proxy_redo */
	"clip_arp_cache",
	{			/* neigh_parms */
		NULL,		/* next */
		NULL,		/* neigh_setup */
		&clip_tbl,	/* tbl */
		0,		/* entries */
		NULL,		/* priv */
		NULL,		/* sysctl_table */
		30*HZ,		/* base_reachable_time */
		1*HZ,		/* retrans_time */
		60*HZ,		/* gc_staletime */
		30*HZ,		/* reachable_time */
		5*HZ,		/* delay_probe_time */
		3,		/* queue_len */
		3,		/* ucast_probes */
		0,		/* app_probes */
		3,		/* mcast_probes */
		1*HZ,		/* anycast_delay */
		(8*HZ)/10,	/* proxy_delay */
		1*HZ,		/* proxy_qlen */
		64		/* locktime */
	},
	30*HZ,128,512,1024	/* copied from ARP ... */
};


/* @@@ 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.
 */


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 atmarp_entry *entry;

	DPRINTK("clip_start_xmit (skb %p)\n",skb);
	if (!skb->dst) {
		printk(KERN_ERR "clip_start_xmit: skb->dst == NULL\n");
		dev_kfree_skb(skb);
		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 */
			PRIV(dev)->stats.tx_dropped++;
			return 0;
		}
#endif
printk("clip_start_xmit: NO NEIGHBOUR !\n");
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);
			PRIV(dev)->stats.tx_dropped++;
		}
		return 0;
	}
	DPRINTK("neigh %p, vccs %p\n",entry,entry->vccs);
	ATM_SKB(skb)->vcc = entry->vccs->vcc;
	DPRINTK("using neighbour %p, vcc %p\n",skb->dst->neighbour,
	    ATM_SKB(skb)->vcc);
	if (entry->vccs->encap) {
		void *here;

		here = skb_push(skb,RFC1483LLC_LEN);
		memcpy(here,llc_oui,sizeof(llc_oui));
		((u16 *) here)[3] = skb->protocol;
	}
	atomic_add(skb->truesize,&ATM_SKB(skb)->vcc->tx_inuse);
	ATM_SKB(skb)->iovcnt = 0;
	ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
	entry->vccs->last_use = jiffies;
	DPRINTK("atm_skb(%p)->vcc(%p)->dev(%p)\n",skb,ATM_SKB(skb)->vcc,
	    ATM_SKB(skb)->vcc->dev);
	PRIV(dev)->stats.tx_packets++;
	PRIV(dev)->stats.tx_bytes += skb->len;
	(void) ATM_SKB(skb)->vcc->dev->ops->send(ATM_SKB(skb)->vcc,skb);
	return 0;
}


static struct net_device_stats *clip_get_stats(struct net_device *dev)
{
	return &PRIV(dev)->stats;
}


int clip_mkip(struct atm_vcc *vcc,int timeout)
{
	struct clip_vcc *clip_vcc;
	struct sk_buff_head copy;
	struct sk_buff *skb;
	unsigned long flags;

	if (!vcc->push) return -EBADFD;
	clip_vcc = kmalloc(sizeof(struct clip_vcc),GFP_KERNEL);
	if (!clip_vcc) return -ENOMEM;
	DPRINTK("mkip clip_vcc %p vcc %p\n",clip_vcc,vcc);
	clip_vcc->vcc = vcc;
	vcc->user_back = clip_vcc;
	clip_vcc->entry = NULL;
	clip_vcc->encap = 1;
	clip_vcc->last_use = jiffies;
	clip_vcc->idle_timeout = timeout*HZ;
	clip_vcc->old_push = vcc->push;
	save_flags(flags);
	cli();
	vcc->push = clip_push;
	skb_migrate(&vcc->recvq,&copy);
	restore_flags(flags);
	/* re-process everything received between connection setup and MKIP */
	while ((skb = skb_dequeue(&copy)))
		if (!clip_devs) {
			atm_return(vcc,skb->truesize);
			kfree_skb(skb);
		}
		else {
			unsigned int len = skb->len;

			clip_push(vcc,skb);
			PRIV(skb->dev)->stats.rx_packets--;
			PRIV(skb->dev)->stats.rx_bytes -= len;
		}
	return 0;
}


int clip_setentry(struct atm_vcc *vcc,u32 ip)
{
	struct neighbour *neigh;
	struct atmarp_entry *entry;
	int error;
	struct clip_vcc *clip_vcc;
	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;
		}
		DPRINTK("setentry: remove\n");
		unlink_clip_vcc(clip_vcc);
		return 0;
	}
	error = ip_route_output(&rt,ip,0,1,0);
	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) DPRINTK("setentry: add\n");
		else {
			DPRINTK("setentry: update\n");
			unlink_clip_vcc(clip_vcc);
		}
		link_vcc(clip_vcc,entry);
	}
	error = neigh_update(neigh,llc_oui,NUD_PERMANENT,1,0);
	neigh_release(neigh);
	return error;
}


static int clip_init(struct net_device *dev)
{
	DPRINTK("clip_init %s\n",dev->name);
	dev->hard_start_xmit = clip_start_xmit;
	/* sg_xmit ... */
	dev->hard_header = NULL;
	dev->rebuild_header = NULL;
	dev->set_mac_address = NULL;
	dev->hard_header_parse = NULL;
	dev->hard_header_cache = NULL;
	dev->header_cache_update = NULL;
	dev->change_mtu = NULL;
	dev->do_ioctl = NULL;
	dev->get_stats = clip_get_stats;
	dev->type = ARPHRD_ATM;
	dev->hard_header_len = RFC1483LLC_LEN;
	dev->mtu = RFC1626_MTU;
	dev->addr_len = 0;
	dev->tx_queue_len = 0;
	dev->flags = 0;
	dev_init_buffers(dev); /* is this ever supposed to be used ? */
	return 0;
}


int clip_create(int number)
{
	struct net_device *dev;
	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 = kmalloc(sizeof(struct net_device)+sizeof(struct clip_priv),
	    GFP_KERNEL); 
	if (!dev) return -ENOMEM;
	memset(dev,0,sizeof(struct net_device)+sizeof(struct clip_priv));
	dev->name = PRIV(dev)->name;
	sprintf(dev->name,"atm%d",number);
	dev->init = clip_init;
	PRIV(dev)->number = number;
	error = register_netdev(dev);
	if (error) {
		kfree(dev);
		return error;
	}
	PRIV(dev)->next = clip_devs;
	clip_devs = dev;
	DPRINTK("registered (net:%s)\n",dev->name);
	return number;
}


static int clip_device_event(struct notifier_block *this,unsigned long event,
    void *dev)
{
	/* ignore non-CLIP devices */
	if (((struct net_device *) dev)->type != ARPHRD_ATM ||
	    ((struct net_device *) dev)->init != clip_init)
		return NOTIFY_DONE;
	switch (event) {
		case NETDEV_UP:
			DPRINTK("clip_device_event NETDEV_UP\n");
			(void) to_atmarpd(act_up,PRIV(dev)->number,0);
			break;
		case NETDEV_DOWN:
			DPRINTK("clip_device_event NETDEV_DOWN\n");
			(void) to_atmarpd(act_down,PRIV(dev)->number,0);
			break;
		case NETDEV_CHANGE:
		case NETDEV_CHANGEMTU:
			DPRINTK("clip_device_event NETDEV_CHANGE*\n");
			(void) to_atmarpd(act_change,PRIV(dev)->number,0);
			break;
		case NETDEV_REBOOT:
		case NETDEV_REGISTER:
			DPRINTK("clip_device_event %ld\n",event);
			/* ignore */
			break;
		default:
			printk(KERN_WARNING "clip_device_event: unknown event "
			    "%ld\n",event);
			break;
	}
	return NOTIFY_DONE;
}


static int clip_inet_event(struct notifier_block *this,unsigned long event,
    void *ifa)
{
	struct in_device *in_dev;

	in_dev = ((struct in_ifaddr *) ifa)->ifa_dev;
	if (!in_dev || !in_dev->dev) {
		printk(KERN_WARNING "clip_inet_event: no device\n");
		return NOTIFY_DONE;
	}
	/*
	 * Transitions are of the down-change-up type, so it's sufficient to
	 * handle the change on up.
	 */
	if (event != NETDEV_UP) return NOTIFY_DONE;
	return clip_device_event(this,NETDEV_CHANGE,in_dev->dev);
}


static struct notifier_block clip_dev_notifier = {
	clip_device_event,
	NULL,
	0
};



static struct notifier_block clip_inet_notifier = {
	clip_inet_event,
	NULL,
	0
};



static void atmarpd_close(struct atm_vcc *vcc)
{
	struct sk_buff *skb;

	DPRINTK("atmarpd_close\n");
	atmarpd = NULL; /* assumed to be atomic */
	barrier();
	unregister_inetaddr_notifier(&clip_inet_notifier);
	unregister_netdevice_notifier(&clip_dev_notifier);
	if (skb_peek(&vcc->recvq))
		printk(KERN_ERR "atmarpd_close: closing with requests "
		    "pending\n");
	while ((skb = skb_dequeue(&vcc->recvq))) kfree_skb(skb);
	DPRINTK("(done)\n");
}


static struct atmdev_ops atmarpd_dev_ops = {
	NULL,		/* no dev_close */
	NULL,		/* no open */
	atmarpd_close,	/* close */
	NULL,		/* no ioctl */
	NULL,		/* no getsockopt */
	NULL,		/* no setsockopt */
	NULL,		/* send */
	NULL,		/* no sg_send */
	NULL,		/* no send_oam */
	NULL,		/* no phy_put */
	NULL,		/* no phy_get */
	NULL,		/* no feedback */
	NULL,		/* no change_qos */
	NULL		/* no free_rx_skb */
};


static struct atm_dev atmarpd_dev = {
	&atmarpd_dev_ops,
	NULL,		/* no PHY */
	"arpd",		/* type */
	999,		/* dummy device number */
	NULL,NULL,	/* pretend not to have any VCCs */
	NULL,NULL,	/* no data */
	0,		/* no flags */
	NULL,		/* no local address */
	{ 0 }		/* no ESI, no statistics */
};


int atm_init_atmarp(struct atm_vcc *vcc)
{
	struct net_device *dev;

	if (atmarpd) return -EADDRINUSE;
	if (start_timer) {
		start_timer = 0;
		init_timer(&idle_timer);
		idle_timer.expires = jiffies+CLIP_CHECK_INTERVAL*HZ;
		idle_timer.function = idle_timer_check;
		add_timer(&idle_timer);
	}
	atmarpd = vcc;
	vcc->flags |= ATM_VF_READY | ATM_VF_META;
	    /* allow replies and avoid getting closed if signaling dies */
	bind_vcc(vcc,&atmarpd_dev);
	vcc->push = NULL;
	vcc->pop = NULL; /* crash */
	vcc->push_oam = NULL; /* crash */
	if (register_netdevice_notifier(&clip_dev_notifier))
		printk(KERN_ERR "register_netdevice_notifier failed\n");
	if (register_inetaddr_notifier(&clip_inet_notifier))
		printk(KERN_ERR "register_inetaddr_notifier failed\n");
	for (dev = clip_devs; dev; dev = PRIV(dev)->next)
		if (dev->flags & IFF_UP)
			(void) to_atmarpd(act_up,PRIV(dev)->number,0);
	return 0;
}


void atm_clip_init(void)
{
	clip_tbl.lock = RW_LOCK_UNLOCKED;
	clip_tbl.kmem_cachep = kmem_cache_create(clip_tbl.id,
	    clip_tbl.entry_size, 0, SLAB_HWCACHE_ALIGN, NULL, NULL);
}