/*
   * DLCI		Implementation of Frame Relay protocol for Linux, according to
   *		RFC 1490.  This generic device provides en/decapsulation for an
   *		underlying hardware driver.  Routes & IPs are assigned to these
   *		interfaces.  Requires 'dlcicfg' program to create usable 
   *		interfaces, the initial one, 'dlci' is for IOCTL use only.
   *
   * Version:	@(#)dlci.c	0.35	4 Jan 1997
   *
   * Author:	Mike McLagan <mike.mclagan@linux.org>
   *
   * Changes:
   *
   *		0.15	Mike Mclagan	Packet freeing, bug in kmalloc call
   *					DLCI_RET handling
   *		0.20	Mike McLagan	More conservative on which packets
   *					are returned for retry and which are
   *					are dropped.  If DLCI_RET_DROP is
   *					returned from the FRAD, the packet is
   *				 	sent back to Linux for re-transmission
   *		0.25	Mike McLagan	Converted to use SIOC IOCTL calls
   *		0.30	Jim Freeman	Fixed to allow IPX traffic
   *		0.35	Michael Elizabeth	Fixed incorrect memcpy_fromfs
   *
   *		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/module.h>
  #include <linux/kernel.h>
  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/interrupt.h>
  #include <linux/ptrace.h>
  #include <linux/ioport.h>
  #include <linux/in.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>
  #include <linux/if_arp.h>
  #include <linux/if_frad.h>
  #include <linux/bitops.h>
  
  #include <net/sock.h>
  
  #include <asm/system.h>
  #include <asm/io.h>
  #include <asm/dma.h>
  #include <asm/uaccess.h>
  
  static const char version[] = "DLCI driver v0.35, 4 Jan 1997, mike.mclagan@linux.org";
  
  static LIST_HEAD(dlci_devs);
  
  static void dlci_setup(struct net_device *);
  
  /* 
   * these encapsulate the RFC 1490 requirements as well as 
   * deal with packet transmission and reception, working with
   * the upper network layers 
   */
  
  static int dlci_header(struct sk_buff *skb, struct net_device *dev, 

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

  {
  	struct frhdr		hdr;
  	struct dlci_local	*dlp;
  	unsigned int		hlen;
  	char			*dest;

  	dlp = netdev_priv(dev);

  
  	hdr.control = FRAD_I_UI;

  	switch (type)

  	{
  		case ETH_P_IP:
  			hdr.IP_NLPID = FRAD_P_IP;
  			hlen = sizeof(hdr.control) + sizeof(hdr.IP_NLPID);
  			break;
  
  		/* feel free to add other types, if necessary */
  
  		default:
  			hdr.pad = FRAD_P_PADDING;
  			hdr.NLPID = FRAD_P_SNAP;
  			memset(hdr.OUI, 0, sizeof(hdr.OUI));
  			hdr.PID = htons(type);
  			hlen = sizeof(hdr);
  			break;
  	}
  
  	dest = skb_push(skb, hlen);
  	if (!dest)
  		return(0);
  
  	memcpy(dest, &hdr, hlen);
  
  	return(hlen);
  }
  
  static void dlci_receive(struct sk_buff *skb, struct net_device *dev)
  {
  	struct dlci_local *dlp;
  	struct frhdr		*hdr;
  	int					process, header;

  	dlp = netdev_priv(dev);

  	if (!pskb_may_pull(skb, sizeof(*hdr))) {
  		printk(KERN_NOTICE "%s: invalid data no header
  ",
  		       dev->name);

  		dev->stats.rx_errors++;

  		kfree_skb(skb);
  		return;
  	}
  
  	hdr = (struct frhdr *) skb->data;
  	process = 0;
  	header = 0;
  	skb->dev = dev;
  
  	if (hdr->control != FRAD_I_UI)
  	{
  		printk(KERN_NOTICE "%s: Invalid header flag 0x%02X.
  ", dev->name, hdr->control);

  		dev->stats.rx_errors++;

  	}
  	else

  		switch (hdr->IP_NLPID)

  		{
  			case FRAD_P_PADDING:
  				if (hdr->NLPID != FRAD_P_SNAP)
  				{
  					printk(KERN_NOTICE "%s: Unsupported NLPID 0x%02X.
  ", dev->name, hdr->NLPID);

  					dev->stats.rx_errors++;

  					break;
  				}
  	 
  				if (hdr->OUI[0] + hdr->OUI[1] + hdr->OUI[2] != 0)
  				{
  					printk(KERN_NOTICE "%s: Unsupported organizationally unique identifier 0x%02X-%02X-%02X.
  ", dev->name, hdr->OUI[0], hdr->OUI[1], hdr->OUI[2]);

  					dev->stats.rx_errors++;

  					break;
  				}
  
  				/* at this point, it's an EtherType frame */
  				header = sizeof(struct frhdr);
  				/* Already in network order ! */
  				skb->protocol = hdr->PID;
  				process = 1;
  				break;
  
  			case FRAD_P_IP:
  				header = sizeof(hdr->control) + sizeof(hdr->IP_NLPID);
  				skb->protocol = htons(ETH_P_IP);
  				process = 1;
  				break;
  
  			case FRAD_P_SNAP:
  			case FRAD_P_Q933:
  			case FRAD_P_CLNP:
  				printk(KERN_NOTICE "%s: Unsupported NLPID 0x%02X.
  ", dev->name, hdr->pad);

  				dev->stats.rx_errors++;

  				break;
  
  			default:
  				printk(KERN_NOTICE "%s: Invalid pad byte 0x%02X.
  ", dev->name, hdr->pad);

  				dev->stats.rx_errors++;

  				break;				
  		}
  
  	if (process)
  	{
  		/* we've set up the protocol, so discard the header */

  		skb_reset_mac_header(skb);

  		skb_pull(skb, header);

  		dev->stats.rx_bytes += skb->len;

  		netif_rx(skb);

  		dev->stats.rx_packets++;

  	}
  	else
  		dev_kfree_skb(skb);
  }

  static netdev_tx_t dlci_transmit(struct sk_buff *skb, struct net_device *dev)

  {

  	struct dlci_local *dlp = netdev_priv(dev);

  	if (skb)
  		dlp->slave->netdev_ops->ndo_start_xmit(skb, dlp->slave);
  	return NETDEV_TX_OK;

  }
  
  static int dlci_config(struct net_device *dev, struct dlci_conf __user *conf, int get)
  {
  	struct dlci_conf	config;
  	struct dlci_local	*dlp;
  	struct frad_local	*flp;
  	int			err;

  	dlp = netdev_priv(dev);

  	flp = netdev_priv(dlp->slave);

  
  	if (!get)
  	{

  		if (copy_from_user(&config, conf, sizeof(struct dlci_conf)))

  			return -EFAULT;
  		if (config.flags & ~DLCI_VALID_FLAGS)
  			return(-EINVAL);
  		memcpy(&dlp->config, &config, sizeof(struct dlci_conf));
  		dlp->configured = 1;
  	}
  
  	err = (*flp->dlci_conf)(dlp->slave, dev, get);
  	if (err)
  		return(err);
  
  	if (get)
  	{

  		if (copy_to_user(conf, &dlp->config, sizeof(struct dlci_conf)))

  			return -EFAULT;
  	}
  
  	return(0);
  }
  
  static int dlci_dev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
  {
  	struct dlci_local *dlp;
  
  	if (!capable(CAP_NET_ADMIN))
  		return(-EPERM);

  	dlp = netdev_priv(dev);

  	switch (cmd)

  	{
  		case DLCI_GET_SLAVE:
  			if (!*(short *)(dev->dev_addr))
  				return(-EINVAL);
  
  			strncpy(ifr->ifr_slave, dlp->slave->name, sizeof(ifr->ifr_slave));
  			break;
  
  		case DLCI_GET_CONF:
  		case DLCI_SET_CONF:
  			if (!*(short *)(dev->dev_addr))
  				return(-EINVAL);
  
  			return(dlci_config(dev, ifr->ifr_data, cmd == DLCI_GET_CONF));
  			break;
  
  		default: 
  			return(-EOPNOTSUPP);
  	}
  	return(0);
  }
  
  static int dlci_change_mtu(struct net_device *dev, int new_mtu)
  {

  	struct dlci_local *dlp = netdev_priv(dev);

  	return dev_set_mtu(dlp->slave, new_mtu);

  }
  
  static int dlci_open(struct net_device *dev)
  {
  	struct dlci_local	*dlp;
  	struct frad_local	*flp;
  	int			err;

  	dlp = netdev_priv(dev);

  
  	if (!*(short *)(dev->dev_addr))
  		return(-EINVAL);
  
  	if (!netif_running(dlp->slave))
  		return(-ENOTCONN);

  	flp = netdev_priv(dlp->slave);

  	err = (*flp->activate)(dlp->slave, dev);
  	if (err)
  		return(err);
  
  	netif_start_queue(dev);
  
  	return 0;
  }
  
  static int dlci_close(struct net_device *dev)
  {
  	struct dlci_local	*dlp;
  	struct frad_local	*flp;
  	int			err;
  
  	netif_stop_queue(dev);

  	dlp = netdev_priv(dev);

  	flp = netdev_priv(dlp->slave);

  	err = (*flp->deactivate)(dlp->slave, dev);
  
  	return 0;
  }

  static int dlci_add(struct dlci_add *dlci)
  {
  	struct net_device	*master, *slave;
  	struct dlci_local	*dlp;
  	struct frad_local	*flp;
  	int			err = -EINVAL;
  
  
  	/* validate slave device */

  	slave = dev_get_by_name(&init_net, dlci->devname);

  	if (!slave)
  		return -ENODEV;

  	if (slave->type != ARPHRD_FRAD || netdev_priv(slave) == NULL)

  		goto err1;
  
  	/* create device name */
  	master = alloc_netdev( sizeof(struct dlci_local), "dlci%d",
  			      dlci_setup);
  	if (!master) {
  		err = -ENOMEM;
  		goto err1;
  	}
  
  	/* make sure same slave not already registered */
  	rtnl_lock();
  	list_for_each_entry(dlp, &dlci_devs, list) {
  		if (dlp->slave == slave) {
  			err = -EBUSY;
  			goto err2;
  		}
  	}
  
  	err = dev_alloc_name(master, master->name);
  	if (err < 0)
  		goto err2;
  
  	*(short *)(master->dev_addr) = dlci->dlci;

  	dlp = netdev_priv(master);

  	dlp->slave = slave;
  	dlp->master = master;

  	flp = netdev_priv(slave);

  	err = (*flp->assoc)(slave, master);
  	if (err < 0)
  		goto err2;
  
  	err = register_netdevice(master);
  	if (err < 0) 
  		goto err2;
  
  	strcpy(dlci->devname, master->name);
  
  	list_add(&dlp->list, &dlci_devs);
  	rtnl_unlock();
  
  	return(0);
  
   err2:
  	rtnl_unlock();
  	free_netdev(master);
   err1:
  	dev_put(slave);
  	return(err);
  }
  
  static int dlci_del(struct dlci_add *dlci)
  {
  	struct dlci_local	*dlp;
  	struct frad_local	*flp;
  	struct net_device	*master, *slave;
  	int			err;
  
  	/* validate slave device */

  	master = __dev_get_by_name(&init_net, dlci->devname);

  	if (!master)
  		return(-ENODEV);
  
  	if (netif_running(master)) {
  		return(-EBUSY);
  	}

  	dlp = netdev_priv(master);

  	slave = dlp->slave;

  	flp = netdev_priv(slave);

  
  	rtnl_lock();
  	err = (*flp->deassoc)(slave, master);
  	if (!err) {
  		list_del(&dlp->list);
  
  		unregister_netdevice(master);
  
  		dev_put(slave);
  	}
  	rtnl_unlock();
  
  	return(err);
  }
  
  static int dlci_ioctl(unsigned int cmd, void __user *arg)
  {
  	struct dlci_add add;
  	int err;
  	
  	if (!capable(CAP_NET_ADMIN))
  		return(-EPERM);

  	if (copy_from_user(&add, arg, sizeof(struct dlci_add)))

  		return -EFAULT;
  
  	switch (cmd)
  	{
  		case SIOCADDDLCI:
  			err = dlci_add(&add);
  
  			if (!err)

  				if (copy_to_user(arg, &add, sizeof(struct dlci_add)))

  					return -EFAULT;
  			break;
  
  		case SIOCDELDLCI:
  			err = dlci_del(&add);
  			break;
  
  		default:
  			err = -EINVAL;
  	}
  
  	return(err);
  }

  static const struct header_ops dlci_header_ops = {
  	.create	= dlci_header,
  };

  static const struct net_device_ops dlci_netdev_ops = {
  	.ndo_open	= dlci_open,
  	.ndo_stop	= dlci_close,
  	.ndo_do_ioctl	= dlci_dev_ioctl,
  	.ndo_start_xmit	= dlci_transmit,
  	.ndo_change_mtu	= dlci_change_mtu,
  };

  static void dlci_setup(struct net_device *dev)
  {

  	struct dlci_local *dlp = netdev_priv(dev);

  
  	dev->flags		= 0;

  	dev->header_ops		= &dlci_header_ops;

  	dev->netdev_ops		= &dlci_netdev_ops;

  	dev->destructor		= free_netdev;
  
  	dlp->receive		= dlci_receive;
  
  	dev->type		= ARPHRD_DLCI;
  	dev->hard_header_len	= sizeof(struct frhdr);
  	dev->addr_len		= sizeof(short);
  
  }
  
  /* if slave is unregistering, then cleanup master */
  static int dlci_dev_event(struct notifier_block *unused,
  			  unsigned long event, void *ptr)
  {
  	struct net_device *dev = (struct net_device *) ptr;

  	if (dev_net(dev) != &init_net)

  		return NOTIFY_DONE;

  	if (event == NETDEV_UNREGISTER) {
  		struct dlci_local *dlp;
  
  		list_for_each_entry(dlp, &dlci_devs, list) {
  			if (dlp->slave == dev) {
  				list_del(&dlp->list);
  				unregister_netdevice(dlp->master);
  				dev_put(dlp->slave);
  				break;
  			}
  		}
  	}
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block dlci_notifier = {
  	.notifier_call = dlci_dev_event,
  };
  
  static int __init init_dlci(void)
  {
  	dlci_ioctl_set(dlci_ioctl);
  	register_netdevice_notifier(&dlci_notifier);
  
  	printk("%s.
  ", version);
  
  	return 0;
  }
  
  static void __exit dlci_exit(void)
  {
  	struct dlci_local	*dlp, *nxt;
  	
  	dlci_ioctl_set(NULL);
  	unregister_netdevice_notifier(&dlci_notifier);
  
  	rtnl_lock();
  	list_for_each_entry_safe(dlp, nxt, &dlci_devs, list) {
  		unregister_netdevice(dlp->master);
  		dev_put(dlp->slave);
  	}
  	rtnl_unlock();
  }
  
  module_init(init_dlci);
  module_exit(dlci_exit);
  
  MODULE_AUTHOR("Mike McLagan");
  MODULE_DESCRIPTION("Frame Relay DLCI layer");
  MODULE_LICENSE("GPL");