/*
   * NET3:	Token ring device handling subroutines

   *

   *		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.
   *
   * Fixes:       3 Feb 97 Paul Norton <pnorton@cts.com> Minor routing fixes.
   *              Added rif table to /proc/net/tr_rif and rif timeout to
   *              /proc/sys/net/token-ring/rif_timeout.
   *              22 Jun 98 Paul Norton <p.norton@computer.org> Rearranged
   *              tr_header and tr_type_trans to handle passing IPX SNAP and
   *              802.2 through the correct layers. Eliminated tr_reformat.

   *

   */
  
  #include <asm/uaccess.h>
  #include <asm/system.h>

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/jiffies.h>
  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <linux/trdevice.h>
  #include <linux/skbuff.h>
  #include <linux/errno.h>
  #include <linux/timer.h>
  #include <linux/net.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/init.h>
  #include <net/arp.h>

  #include <net/net_namespace.h>

  
  static void tr_add_rif_info(struct trh_hdr *trh, struct net_device *dev);
  static void rif_check_expire(unsigned long dummy);
  
  #define TR_SR_DEBUG 0
  
  /*
   *	Each RIF entry we learn is kept this way
   */

  struct rif_cache {

  	unsigned char addr[TR_ALEN];
  	int iface;

  	__be16 rcf;
  	__be16 rseg[8];

  	struct rif_cache *next;

  	unsigned long last_used;
  	unsigned char local_ring;
  };
  
  #define RIF_TABLE_SIZE 32
  
  /*
   *	We hash the RIF cache 32 ways. We do after all have to look it
   *	up a lot.
   */

  static struct rif_cache *rif_table[RIF_TABLE_SIZE];

  
  static DEFINE_SPINLOCK(rif_lock);
  
  
  /*
   *	Garbage disposal timer.
   */

  static struct timer_list rif_timer;
  
  int sysctl_tr_rif_timeout = 60*10*HZ;
  
  static inline unsigned long rif_hash(const unsigned char *addr)
  {
  	unsigned long x;
  
  	x = addr[0];
  	x = (x << 2) ^ addr[1];
  	x = (x << 2) ^ addr[2];
  	x = (x << 2) ^ addr[3];
  	x = (x << 2) ^ addr[4];
  	x = (x << 2) ^ addr[5];
  
  	x ^= x >> 8;
  
  	return x & (RIF_TABLE_SIZE - 1);
  }
  
  /*
   *	Put the headers on a token ring packet. Token ring source routing
   *	makes this a little more exciting than on ethernet.
   */

  static int tr_header(struct sk_buff *skb, struct net_device *dev,
  		     unsigned short type,

  		     const void *daddr, const void *saddr, unsigned len)

  {
  	struct trh_hdr *trh;
  	int hdr_len;

  	/*
  	 * Add the 802.2 SNAP header if IP as the IPv4/IPv6 code calls

  	 * dev->hard_header directly.
  	 */
  	if (type == ETH_P_IP || type == ETH_P_IPV6 || type == ETH_P_ARP)
  	{
  		struct trllc *trllc;
  
  		hdr_len = sizeof(struct trh_hdr) + sizeof(struct trllc);
  		trh = (struct trh_hdr *)skb_push(skb, hdr_len);
  		trllc = (struct trllc *)(trh+1);
  		trllc->dsap = trllc->ssap = EXTENDED_SAP;
  		trllc->llc = UI_CMD;
  		trllc->protid[0] = trllc->protid[1] = trllc->protid[2] = 0x00;
  		trllc->ethertype = htons(type);
  	}
  	else
  	{
  		hdr_len = sizeof(struct trh_hdr);

  		trh = (struct trh_hdr *)skb_push(skb, hdr_len);

  	}
  
  	trh->ac=AC;
  	trh->fc=LLC_FRAME;
  
  	if(saddr)
  		memcpy(trh->saddr,saddr,dev->addr_len);
  	else
  		memcpy(trh->saddr,dev->dev_addr,dev->addr_len);
  
  	/*
  	 *	Build the destination and then source route the frame
  	 */

  
  	if(daddr)

  	{
  		memcpy(trh->daddr,daddr,dev->addr_len);

  		tr_source_route(skb, trh, dev);

  		return(hdr_len);
  	}
  
  	return -hdr_len;
  }

  /*
   *	A neighbour discovery of some species (eg arp) has completed. We
   *	can now send the packet.
   */

  
  static int tr_rebuild_header(struct sk_buff *skb)

  {
  	struct trh_hdr *trh=(struct trh_hdr *)skb->data;
  	struct trllc *trllc=(struct trllc *)(skb->data+sizeof(struct trh_hdr));
  	struct net_device *dev = skb->dev;
  
  	/*
  	 *	FIXME: We don't yet support IPv6 over token rings
  	 */

  	if(trllc->ethertype != htons(ETH_P_IP)) {

  		printk("tr_rebuild_header: Don't know how to resolve type %04X addresses ?
  ", ntohs(trllc->ethertype));

  		return 0;
  	}
  
  #ifdef CONFIG_INET
  	if(arp_find(trh->daddr, skb)) {
  			return 1;
  	}

  	else
  #endif
  	{
  		tr_source_route(skb,trh,dev);

  		return 0;
  	}
  }

  /*
   *	Some of this is a bit hackish. We intercept RIF information
   *	used for source routing. We also grab IP directly and don't feed
   *	it via SNAP.
   */

  __be16 tr_type_trans(struct sk_buff *skb, struct net_device *dev)

  {

  	struct trh_hdr *trh;

  	struct trllc *trllc;
  	unsigned riflen=0;

  	skb->dev = dev;

  	skb_reset_mac_header(skb);

  	trh = tr_hdr(skb);

  
  	if(trh->saddr[0] & TR_RII)

  		riflen = (ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8;
  
  	trllc = (struct trllc *)(skb->data+sizeof(struct trh_hdr)-TR_MAXRIFLEN+riflen);
  
  	skb_pull(skb,sizeof(struct trh_hdr)-TR_MAXRIFLEN+riflen);

  	if(*trh->daddr & 0x80)

  	{

  		if(!memcmp(trh->daddr,dev->broadcast,TR_ALEN))

  			skb->pkt_type=PACKET_BROADCAST;
  		else
  			skb->pkt_type=PACKET_MULTICAST;
  	}
  	else if ( (trh->daddr[0] & 0x01) && (trh->daddr[1] & 0x00) && (trh->daddr[2] & 0x5E))
  	{
  		skb->pkt_type=PACKET_MULTICAST;
  	}

  	else if(dev->flags & IFF_PROMISC)

  	{
  		if(memcmp(trh->daddr, dev->dev_addr, TR_ALEN))
  			skb->pkt_type=PACKET_OTHERHOST;
  	}
  
  	if ((skb->pkt_type != PACKET_BROADCAST) &&
  	    (skb->pkt_type != PACKET_MULTICAST))

  		tr_add_rif_info(trh,dev) ;

  
  	/*

  	 * Strip the SNAP header from ARP packets since we don't

  	 * pass them through to the 802.2/SNAP layers.
  	 */
  
  	if (trllc->dsap == EXTENDED_SAP &&

  	    (trllc->ethertype == htons(ETH_P_IP) ||
  	     trllc->ethertype == htons(ETH_P_IPV6) ||
  	     trllc->ethertype == htons(ETH_P_ARP)))

  	{
  		skb_pull(skb, sizeof(struct trllc));
  		return trllc->ethertype;
  	}

  	return htons(ETH_P_TR_802_2);

  }
  
  /*

   *	We try to do source routing...

   */

  void tr_source_route(struct sk_buff *skb,struct trh_hdr *trh,
  		     struct net_device *dev)

  {
  	int slack;
  	unsigned int hash;

  	struct rif_cache *entry;

  	unsigned char *olddata;

  	unsigned long flags;

  	static const unsigned char mcast_func_addr[]

  		= {0xC0,0x00,0x00,0x04,0x00,0x00};

  	spin_lock_irqsave(&rif_lock, flags);

  
  	/*

  	 *	Broadcasts are single route as stated in RFC 1042

  	 */
  	if( (!memcmp(&(trh->daddr[0]),&(dev->broadcast[0]),TR_ALEN)) ||
  	    (!memcmp(&(trh->daddr[0]),&(mcast_func_addr[0]), TR_ALEN))  )
  	{

  		trh->rcf=htons((((sizeof(trh->rcf)) << 8) & TR_RCF_LEN_MASK)

  			       | TR_RCF_FRAME2K | TR_RCF_LIMITED_BROADCAST);
  		trh->saddr[0]|=TR_RII;
  	}

  	else

  	{
  		hash = rif_hash(trh->daddr);
  		/*
  		 *	Walk the hash table and look for an entry
  		 */
  		for(entry=rif_table[hash];entry && memcmp(&(entry->addr[0]),&(trh->daddr[0]),TR_ALEN);entry=entry->next);
  
  		/*
  		 *	If we found an entry we can route the frame.
  		 */

  		if(entry)

  		{
  #if TR_SR_DEBUG

  {
  DECLARE_MAC_BUF(mac);
  printk("source routing for %s
  ",print_mac(mac, trh->daddr));
  }

  #endif
  			if(!entry->local_ring && (ntohs(entry->rcf) & TR_RCF_LEN_MASK) >> 8)
  			{
  				trh->rcf=entry->rcf;
  				memcpy(&trh->rseg[0],&entry->rseg[0],8*sizeof(unsigned short));

  				trh->rcf^=htons(TR_RCF_DIR_BIT);

  				trh->rcf&=htons(0x1fff);	/* Issam Chehab <ichehab@madge1.demon.co.uk> */
  
  				trh->saddr[0]|=TR_RII;
  #if TR_SR_DEBUG
  				printk("entry found with rcf %04x
  ", entry->rcf);
  			}
  			else
  			{
  				printk("entry found but without rcf length, local=%02x
  ", entry->local_ring);
  #endif
  			}
  			entry->last_used=jiffies;
  		}

  		else

  		{
  			/*
  			 *	Without the information we simply have to shout
  			 *	on the wire. The replies should rapidly clean this
  			 *	situation up.
  			 */

  			trh->rcf=htons((((sizeof(trh->rcf)) << 8) & TR_RCF_LEN_MASK)

  				       | TR_RCF_FRAME2K | TR_RCF_LIMITED_BROADCAST);
  			trh->saddr[0]|=TR_RII;
  #if TR_SR_DEBUG
  			printk("no entry in rif table found - broadcasting frame
  ");
  #endif
  		}
  	}
  
  	/* Compress the RIF here so we don't have to do it in the driver(s) */
  	if (!(trh->saddr[0] & 0x80))
  		slack = 18;

  	else

  		slack = 18 - ((ntohs(trh->rcf) & TR_RCF_LEN_MASK)>>8);
  	olddata = skb->data;

  	spin_unlock_irqrestore(&rif_lock, flags);

  
  	skb_pull(skb, slack);
  	memmove(skb->data, olddata, sizeof(struct trh_hdr) - slack);
  }
  
  /*
   *	We have learned some new RIF information for our source
   *	routing.
   */

  static void tr_add_rif_info(struct trh_hdr *trh, struct net_device *dev)
  {
  	unsigned int hash, rii_p = 0;

  	unsigned long flags;

  	struct rif_cache *entry;

  	unsigned char saddr0;

  	spin_lock_irqsave(&rif_lock, flags);

  	saddr0 = trh->saddr[0];

  	/*
  	 *	Firstly see if the entry exists
  	 */

  	if(trh->saddr[0] & TR_RII)

  	{
  		trh->saddr[0]&=0x7f;
  		if (((ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8) > 2)
  		{
  			rii_p = 1;

  		}

  	}
  
  	hash = rif_hash(trh->saddr);
  	for(entry=rif_table[hash];entry && memcmp(&(entry->addr[0]),&(trh->saddr[0]),TR_ALEN);entry=entry->next);

  	if(entry==NULL)

  	{
  #if TR_SR_DEBUG

  		DECLARE_MAC_BUF(mac);
  		printk("adding rif_entry: addr:%s rcf:%04X
  ",
  		       print_mac(mac, trh->saddr), ntohs(trh->rcf));

  #endif
  		/*
  		 *	Allocate our new entry. A failure to allocate loses
  		 *	use the information. This is harmless.
  		 *
  		 *	FIXME: We ought to keep some kind of cache size
  		 *	limiting and adjust the timers to suit.
  		 */

  		entry=kmalloc(sizeof(struct rif_cache),GFP_ATOMIC);

  		if(!entry)

  		{
  			printk(KERN_DEBUG "tr.c: Couldn't malloc rif cache entry !
  ");

  			spin_unlock_irqrestore(&rif_lock, flags);

  			return;
  		}
  
  		memcpy(&(entry->addr[0]),&(trh->saddr[0]),TR_ALEN);
  		entry->iface = dev->ifindex;
  		entry->next=rif_table[hash];
  		entry->last_used=jiffies;
  		rif_table[hash]=entry;
  
  		if (rii_p)
  		{
  			entry->rcf = trh->rcf & htons((unsigned short)~TR_RCF_BROADCAST_MASK);
  			memcpy(&(entry->rseg[0]),&(trh->rseg[0]),8*sizeof(unsigned short));
  			entry->local_ring = 0;

  		}
  		else
  		{
  			entry->local_ring = 1;
  		}

  	}

  	else	/* Y. Tahara added */

  	{

  		/*
  		 *	Update existing entries
  		 */

  		if (!entry->local_ring)

  		    if (entry->rcf != (trh->rcf & htons((unsigned short)~TR_RCF_BROADCAST_MASK)) &&
  			 !(trh->rcf & htons(TR_RCF_BROADCAST_MASK)))
  		    {
  #if TR_SR_DEBUG

  {
  DECLARE_MAC_BUF(mac);
  printk("updating rif_entry: addr:%s rcf:%04X
  ",
  		print_mac(mac, trh->saddr), ntohs(trh->rcf));
  }

  #endif
  			    entry->rcf = trh->rcf & htons((unsigned short)~TR_RCF_BROADCAST_MASK);

  			    memcpy(&(entry->rseg[0]),&(trh->rseg[0]),8*sizeof(unsigned short));
  		    }
  		entry->last_used=jiffies;

  	}

  	trh->saddr[0]=saddr0; /* put the routing indicator back for tcpdump */

  	spin_unlock_irqrestore(&rif_lock, flags);

  }
  
  /*
   *	Scan the cache with a timer and see what we need to throw out.
   */

  static void rif_check_expire(unsigned long dummy)

  {
  	int i;

  	unsigned long flags, next_interval = jiffies + sysctl_tr_rif_timeout/2;

  	spin_lock_irqsave(&rif_lock, flags);

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

  		struct rif_cache *entry, **pentry;

  		pentry = rif_table+i;
  		while((entry=*pentry) != NULL) {
  			unsigned long expires
  				= entry->last_used + sysctl_tr_rif_timeout;
  
  			if (time_before_eq(expires, jiffies)) {
  				*pentry = entry->next;
  				kfree(entry);
  			} else {
  				pentry = &entry->next;
  
  				if (time_before(expires, next_interval))
  					next_interval = expires;
  			}
  		}
  	}

  	spin_unlock_irqrestore(&rif_lock, flags);

  
  	mod_timer(&rif_timer, next_interval);
  
  }
  
  /*
   *	Generate the /proc/net information for the token ring RIF
   *	routing.
   */

  #ifdef CONFIG_PROC_FS

  static struct rif_cache *rif_get_idx(loff_t pos)

  {
  	int i;

  	struct rif_cache *entry;

  	loff_t off = 0;

  	for(i = 0; i < RIF_TABLE_SIZE; i++)

  		for(entry = rif_table[i]; entry; entry = entry->next) {
  			if (off == pos)
  				return entry;
  			++off;
  		}
  
  	return NULL;
  }
  
  static void *rif_seq_start(struct seq_file *seq, loff_t *pos)
  {

  	spin_lock_irq(&rif_lock);

  
  	return *pos ? rif_get_idx(*pos - 1) : SEQ_START_TOKEN;
  }
  
  static void *rif_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	int i;

  	struct rif_cache *ent = v;

  
  	++*pos;
  
  	if (v == SEQ_START_TOKEN) {
  		i = -1;
  		goto scan;
  	}

  	if (ent->next)

  		return ent->next;
  
  	i = rif_hash(ent->addr);
   scan:
  	while (++i < RIF_TABLE_SIZE) {
  		if ((ent = rif_table[i]) != NULL)
  			return ent;
  	}
  	return NULL;
  }
  
  static void rif_seq_stop(struct seq_file *seq, void *v)
  {

  	spin_unlock_irq(&rif_lock);

  }
  
  static int rif_seq_show(struct seq_file *seq, void *v)
  {
  	int j, rcf_len, segment, brdgnmb;

  	struct rif_cache *entry = v;

  	DECLARE_MAC_BUF(mac);

  
  	if (v == SEQ_START_TOKEN)
  		seq_puts(seq,
  		     "if     TR address       TTL   rcf   routing segments
  ");
  	else {

  		struct net_device *dev = dev_get_by_index(&init_net, entry->iface);

  		long ttl = (long) (entry->last_used + sysctl_tr_rif_timeout)
  				- (long) jiffies;

  		seq_printf(seq, "%s %s %7li ",

  			   dev?dev->name:"?",

  			   print_mac(mac, entry->addr),

  			   ttl/HZ);
  
  			if (entry->local_ring)

  				seq_puts(seq, "local
  ");

  			else {
  
  				seq_printf(seq, "%04X", ntohs(entry->rcf));

  				rcf_len = ((ntohs(entry->rcf) & TR_RCF_LEN_MASK)>>8)-2;

  				if (rcf_len)

  					rcf_len >>= 1;

  				for(j = 1; j < rcf_len; j++) {
  					if(j==1) {
  						segment=ntohs(entry->rseg[j-1])>>4;
  						seq_printf(seq,"  %03X",segment);

  					}

  					segment=ntohs(entry->rseg[j])>>4;
  					brdgnmb=ntohs(entry->rseg[j-1])&0x00f;
  					seq_printf(seq,"-%01X-%03X",brdgnmb,segment);
  				}
  				seq_putc(seq, '
  ');
  			}

  		}

  	return 0;
  }

  static const struct seq_operations rif_seq_ops = {

  	.start = rif_seq_start,
  	.next  = rif_seq_next,
  	.stop  = rif_seq_stop,
  	.show  = rif_seq_show,
  };
  
  static int rif_seq_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &rif_seq_ops);
  }

  static const struct file_operations rif_seq_fops = {

  	.owner	 = THIS_MODULE,
  	.open    = rif_seq_open,
  	.read    = seq_read,
  	.llseek  = seq_lseek,
  	.release = seq_release,
  };
  
  #endif

  static const struct header_ops tr_header_ops = {
  	.create = tr_header,
  	.rebuild= tr_rebuild_header,
  };

  static void tr_setup(struct net_device *dev)
  {
  	/*
  	 *	Configure and register
  	 */

  	dev->header_ops	= &tr_header_ops;

  
  	dev->type		= ARPHRD_IEEE802_TR;
  	dev->hard_header_len	= TR_HLEN;
  	dev->mtu		= 2000;
  	dev->addr_len		= TR_ALEN;
  	dev->tx_queue_len	= 100;	/* Long queues on tr */

  	memset(dev->broadcast,0xFF, TR_ALEN);
  
  	/* New-style flags. */
  	dev->flags		= IFF_BROADCAST | IFF_MULTICAST ;
  }
  
  /**
   * alloc_trdev - Register token ring device
   * @sizeof_priv: Size of additional driver-private structure to be allocated
   *	for this token ring device
   *
   * Fill in the fields of the device structure with token ring-generic values.
   *
   * Constructs a new net device, complete with a private data area of
   * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
   * this private data area.
   */
  struct net_device *alloc_trdev(int sizeof_priv)
  {
  	return alloc_netdev(sizeof_priv, "tr%d", tr_setup);
  }
  
  /*
   *	Called during bootup.  We don't actually have to initialise
   *	too much for this.
   */
  
  static int __init rif_init(void)
  {
  	init_timer(&rif_timer);
  	rif_timer.expires  = sysctl_tr_rif_timeout;
  	rif_timer.data     = 0L;
  	rif_timer.function = rif_check_expire;
  	add_timer(&rif_timer);

  	proc_net_fops_create(&init_net, "tr_rif", S_IRUGO, &rif_seq_fops);

  	return 0;
  }
  
  module_init(rif_init);

  EXPORT_SYMBOL(tr_type_trans);
  EXPORT_SYMBOL(alloc_trdev);