/*
   *	An implementation of the Acorn Econet and AUN protocols.
   *	Philip Blundell <philb@gnu.org>
   *
   *	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.
   *
   */

  #define pr_fmt(fmt) fmt

  #include <linux/module.h>
  
  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/in.h>
  #include <linux/errno.h>
  #include <linux/interrupt.h>
  #include <linux/if_ether.h>
  #include <linux/netdevice.h>
  #include <linux/inetdevice.h>
  #include <linux/route.h>
  #include <linux/inet.h>
  #include <linux/etherdevice.h>
  #include <linux/if_arp.h>
  #include <linux/wireless.h>
  #include <linux/skbuff.h>

  #include <linux/udp.h>

  #include <linux/slab.h>

  #include <linux/vmalloc.h>

  #include <net/sock.h>
  #include <net/inet_common.h>
  #include <linux/stat.h>
  #include <linux/init.h>
  #include <linux/if_ec.h>
  #include <net/udp.h>
  #include <net/ip.h>
  #include <linux/spinlock.h>
  #include <linux/rcupdate.h>
  #include <linux/bitops.h>

  #include <linux/mutex.h>

  #include <linux/uaccess.h>

  #include <asm/system.h>

  static const struct proto_ops econet_ops;

  static struct hlist_head econet_sklist;

  static DEFINE_SPINLOCK(econet_lock);

  static DEFINE_MUTEX(econet_mutex);

  
  /* Since there are only 256 possible network numbers (or fewer, depends
     how you count) it makes sense to use a simple lookup table. */
  static struct net_device *net2dev_map[256];
  
  #define EC_PORT_IP	0xd2
  
  #ifdef CONFIG_ECONET_AUNUDP

  static DEFINE_SPINLOCK(aun_queue_lock);

  static struct socket *udpsock;
  #define AUN_PORT	0x8000

  struct aunhdr {

  	unsigned char code;		/* AUN magic protocol byte */
  	unsigned char port;
  	unsigned char cb;
  	unsigned char pad;
  	unsigned long handle;
  };
  
  static unsigned long aun_seq;
  
  /* Queue of packets waiting to be transmitted. */
  static struct sk_buff_head aun_queue;
  static struct timer_list ab_cleanup_timer;
  
  #endif		/* CONFIG_ECONET_AUNUDP */
  
  /* Per-packet information */

  struct ec_cb {

  	struct sockaddr_ec sec;
  	unsigned long cookie;		/* Supplied by user. */
  #ifdef CONFIG_ECONET_AUNUDP
  	int done;
  	unsigned long seq;		/* Sequencing */
  	unsigned long timeout;		/* Timeout */
  	unsigned long start;		/* jiffies */
  #endif
  #ifdef CONFIG_ECONET_NATIVE
  	void (*sent)(struct sk_buff *, int result);
  #endif
  };
  
  static void econet_remove_socket(struct hlist_head *list, struct sock *sk)
  {

  	spin_lock_bh(&econet_lock);

  	sk_del_node_init(sk);

  	spin_unlock_bh(&econet_lock);

  }
  
  static void econet_insert_socket(struct hlist_head *list, struct sock *sk)
  {

  	spin_lock_bh(&econet_lock);

  	sk_add_node(sk, list);

  	spin_unlock_bh(&econet_lock);

  }
  
  /*
   *	Pull a packet from our receive queue and hand it to the user.
   *	If necessary we block.
   */
  
  static int econet_recvmsg(struct kiocb *iocb, struct socket *sock,
  			  struct msghdr *msg, size_t len, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct sk_buff *skb;
  	size_t copied;
  	int err;
  
  	msg->msg_namelen = sizeof(struct sockaddr_ec);

  	mutex_lock(&econet_mutex);

  	/*
  	 *	Call the generic datagram receiver. This handles all sorts
  	 *	of horrible races and re-entrancy so we can forget about it
  	 *	in the protocol layers.
  	 *
  	 *	Now it will return ENETDOWN, if device have just gone down,
  	 *	but then it will block.
  	 */

  	skb = skb_recv_datagram(sk, flags, flags & MSG_DONTWAIT, &err);

  
  	/*

  	 *	An error occurred so return it. Because skb_recv_datagram()

  	 *	handles the blocking we don't see and worry about blocking
  	 *	retries.
  	 */

  	if (skb == NULL)

  		goto out;
  
  	/*
  	 *	You lose any data beyond the buffer you gave. If it worries a
  	 *	user program they can ask the device for its MTU anyway.
  	 */
  
  	copied = skb->len;

  	if (copied > len) {
  		copied = len;
  		msg->msg_flags |= MSG_TRUNC;

  	}
  
  	/* We can't use skb_copy_datagram here */
  	err = memcpy_toiovec(msg->msg_iov, skb->data, copied);
  	if (err)
  		goto out_free;

  	sk->sk_stamp = skb->tstamp;

  
  	if (msg->msg_name)
  		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
  
  	/*
  	 *	Free or return the buffer as appropriate. Again this
  	 *	hides all the races and re-entrancy issues from us.
  	 */
  	err = copied;
  
  out_free:
  	skb_free_datagram(sk, skb);
  out:

  	mutex_unlock(&econet_mutex);

  	return err;
  }
  
  /*
   *	Bind an Econet socket.
   */

  static int econet_bind(struct socket *sock, struct sockaddr *uaddr,
  		       int addr_len)

  {
  	struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;

  	struct sock *sk;
  	struct econet_sock *eo;

  	/*
  	 *	Check legality
  	 */

  	if (addr_len < sizeof(struct sockaddr_ec) ||
  	    sec->sec_family != AF_ECONET)
  		return -EINVAL;

  	mutex_lock(&econet_mutex);
  
  	sk = sock->sk;
  	eo = ec_sk(sk);

  	eo->cb	    = sec->cb;
  	eo->port    = sec->port;
  	eo->station = sec->addr.station;
  	eo->net	    = sec->addr.net;

  	mutex_unlock(&econet_mutex);

  	return 0;
  }
  
  #if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
  /*
   *	Queue a transmit result for the user to be told about.
   */
  
  static void tx_result(struct sock *sk, unsigned long cookie, int result)
  {
  	struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
  	struct ec_cb *eb;
  	struct sockaddr_ec *sec;

  	if (skb == NULL) {
  		pr_debug("econet: memory squeeze, transmit result dropped
  ");

  		return;
  	}
  
  	eb = (struct ec_cb *)&skb->cb;
  	sec = (struct sockaddr_ec *)&eb->sec;
  	memset(sec, 0, sizeof(struct sockaddr_ec));
  	sec->cookie = cookie;
  	sec->type = ECTYPE_TRANSMIT_STATUS | result;
  	sec->sec_family = AF_ECONET;
  
  	if (sock_queue_rcv_skb(sk, skb) < 0)
  		kfree_skb(skb);
  }
  #endif
  
  #ifdef CONFIG_ECONET_NATIVE
  /*
   *	Called by the Econet hardware driver when a packet transmit
   *	has completed.  Tell the user.
   */
  
  static void ec_tx_done(struct sk_buff *skb, int result)
  {
  	struct ec_cb *eb = (struct ec_cb *)&skb->cb;
  	tx_result(skb->sk, eb->cookie, result);
  }
  #endif
  
  /*
   *	Send a packet.  We have to work out which device it's going out on
   *	and hence whether to use real Econet or the UDP emulation.
   */
  
  static int econet_sendmsg(struct kiocb *iocb, struct socket *sock,
  			  struct msghdr *msg, size_t len)
  {

  	struct sockaddr_ec *saddr = (struct sockaddr_ec *)msg->msg_name;

  	struct net_device *dev;
  	struct ec_addr addr;
  	int err;
  	unsigned char port, cb;
  #if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)

  	struct sock *sk = sock->sk;

  	struct sk_buff *skb;
  	struct ec_cb *eb;
  #endif
  #ifdef CONFIG_ECONET_AUNUDP
  	struct msghdr udpmsg;

  	struct iovec iov[2];

  	struct aunhdr ah;
  	struct sockaddr_in udpdest;
  	__kernel_size_t size;

  	mm_segment_t oldfs;

  	char *userbuf;

  #endif

  	/*

  	 *	Check the flags.

  	 */

  	if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_CMSG_COMPAT))

  		return -EINVAL;
  
  	/*

  	 *	Get and verify the address.

  	 */

  	mutex_lock(&econet_mutex);

  	if (saddr == NULL || msg->msg_namelen < sizeof(struct sockaddr_ec)) {
  		mutex_unlock(&econet_mutex);
  		return -EINVAL;
  	}
  	addr.station = saddr->addr.station;
  	addr.net = saddr->addr.net;
  	port = saddr->port;
  	cb = saddr->cb;

  
  	/* Look for a device with the right network number. */
  	dev = net2dev_map[addr.net];
  
  	/* If not directly reachable, use some default */

  	if (dev == NULL) {

  		dev = net2dev_map[0];
  		/* No interfaces at all? */

  		if (dev == NULL) {
  			mutex_unlock(&econet_mutex);

  			return -ENETDOWN;

  		}

  	}

  	if (dev->type == ARPHRD_ECONET) {

  		/* Real hardware Econet.  We're not worthy etc. */
  #ifdef CONFIG_ECONET_NATIVE
  		unsigned short proto = 0;

  		int hlen, tlen;

  		int res;

  		if (len + 15 > dev->mtu) {
  			mutex_unlock(&econet_mutex);
  			return -EMSGSIZE;
  		}

  		dev_hold(dev);

  		hlen = LL_RESERVED_SPACE(dev);
  		tlen = dev->needed_tailroom;
  		skb = sock_alloc_send_skb(sk, len + hlen + tlen,

  					  msg->msg_flags & MSG_DONTWAIT, &err);

  		if (skb == NULL)

  			goto out_unlock;

  		skb_reserve(skb, hlen);

  		skb_reset_network_header(skb);

  		eb = (struct ec_cb *)&skb->cb;

  		eb->cookie = saddr->cookie;
  		eb->sec = *saddr;
  		eb->sent = ec_tx_done;

  		err = -EINVAL;
  		res = dev_hard_header(skb, dev, ntohs(proto), &addr, NULL, len);
  		if (res < 0)
  			goto out_free;
  		if (res > 0) {

  			struct ec_framehdr *fh;

  			/* Poke in our control byte and
  			   port number.  Hack, hack.  */

  			fh = (struct ec_framehdr *)skb->data;

  			fh->cb = cb;
  			fh->port = port;
  			if (sock->type != SOCK_DGRAM) {

  				skb_reset_tail_pointer(skb);

  				skb->len = 0;

  			}

  		}

  		/* Copy the data. Returns -EFAULT on error */

  		err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);

  		skb->protocol = proto;
  		skb->dev = dev;
  		skb->priority = sk->sk_priority;
  		if (err)
  			goto out_free;

  		err = -ENETDOWN;
  		if (!(dev->flags & IFF_UP))
  			goto out_free;

  		/*
  		 *	Now send it
  		 */

  		dev_queue_xmit(skb);
  		dev_put(dev);

  		mutex_unlock(&econet_mutex);

  		return len;

  out_free:

  		kfree_skb(skb);

  out_unlock:

  		if (dev)
  			dev_put(dev);
  #else
  		err = -EPROTOTYPE;
  #endif

  		mutex_unlock(&econet_mutex);

  		return err;
  	}
  
  #ifdef CONFIG_ECONET_AUNUDP
  	/* AUN virtual Econet. */

  	if (udpsock == NULL) {
  		mutex_unlock(&econet_mutex);

  		return -ENETDOWN;		/* No socket - can't send */

  	}

  	if (len > 32768) {
  		err = -E2BIG;
  		goto error;
  	}

  	/* Make up a UDP datagram and hand it off to some higher intellect. */
  
  	memset(&udpdest, 0, sizeof(udpdest));
  	udpdest.sin_family = AF_INET;
  	udpdest.sin_port = htons(AUN_PORT);
  
  	/* At the moment we use the stupid Acorn scheme of Econet address
  	   y.x maps to IP a.b.c.x.  This should be replaced with something
  	   more flexible and more aware of subnet masks.  */
  	{
  		struct in_device *idev;
  		unsigned long network = 0;
  
  		rcu_read_lock();

  		idev = __in_dev_get_rcu(dev);

  		if (idev) {
  			if (idev->ifa_list)

  				network = ntohl(idev->ifa_list->ifa_address) &

  					0xffffff00;		/* !!! */
  		}
  		rcu_read_unlock();
  		udpdest.sin_addr.s_addr = htonl(network | addr.station);
  	}

  	memset(&ah, 0, sizeof(ah));

  	ah.port = port;
  	ah.cb = cb & 0x7f;
  	ah.code = 2;		/* magic */

  
  	/* tack our header on the front of the iovec */
  	size = sizeof(struct aunhdr);

  	iov[0].iov_base = (void *)&ah;
  	iov[0].iov_len = size;

  
  	userbuf = vmalloc(len);
  	if (userbuf == NULL) {
  		err = -ENOMEM;
  		goto error;

  	}

  	iov[1].iov_base = userbuf;
  	iov[1].iov_len = len;
  	err = memcpy_fromiovec(userbuf, msg->msg_iov, len);
  	if (err)
  		goto error_free_buf;

  	/* Get a skbuff (no data, just holds our cb information) */

  	skb = sock_alloc_send_skb(sk, 0, msg->msg_flags & MSG_DONTWAIT, &err);
  	if (skb == NULL)

  		goto error_free_buf;

  
  	eb = (struct ec_cb *)&skb->cb;
  
  	eb->cookie = saddr->cookie;

  	eb->timeout = 5 * HZ;

  	eb->start = jiffies;
  	ah.handle = aun_seq;
  	eb->seq = (aun_seq++);
  	eb->sec = *saddr;
  
  	skb_queue_tail(&aun_queue, skb);
  
  	udpmsg.msg_name = (void *)&udpdest;
  	udpmsg.msg_namelen = sizeof(udpdest);
  	udpmsg.msg_iov = &iov[0];

  	udpmsg.msg_iovlen = 2;

  	udpmsg.msg_control = NULL;
  	udpmsg.msg_controllen = 0;

  	udpmsg.msg_flags = 0;

  	oldfs = get_fs();
  	set_fs(KERNEL_DS);		/* More privs :-) */

  	err = sock_sendmsg(udpsock, &udpmsg, size);
  	set_fs(oldfs);

  
  error_free_buf:
  	vfree(userbuf);

  error:

  #else
  	err = -EPROTOTYPE;
  #endif

  	mutex_unlock(&econet_mutex);

  	return err;
  }
  
  /*
   *	Look up the address of a socket.
   */
  
  static int econet_getname(struct socket *sock, struct sockaddr *uaddr,
  			  int *uaddr_len, int peer)
  {

  	struct sock *sk;
  	struct econet_sock *eo;

  	struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;
  
  	if (peer)
  		return -EOPNOTSUPP;

  	memset(sec, 0, sizeof(*sec));

  	mutex_lock(&econet_mutex);
  
  	sk = sock->sk;
  	eo = ec_sk(sk);

  	sec->sec_family	  = AF_ECONET;
  	sec->port	  = eo->port;
  	sec->addr.station = eo->station;
  	sec->addr.net	  = eo->net;

  	mutex_unlock(&econet_mutex);

  	*uaddr_len = sizeof(*sec);
  	return 0;
  }
  
  static void econet_destroy_timer(unsigned long data)
  {

  	struct sock *sk = (struct sock *)data;

  	if (!sk_has_allocations(sk)) {

  		sk_free(sk);
  		return;
  	}
  
  	sk->sk_timer.expires = jiffies + 10 * HZ;
  	add_timer(&sk->sk_timer);

  	pr_debug("econet: socket destroy delayed
  ");

  }
  
  /*
   *	Close an econet socket.
   */
  
  static int econet_release(struct socket *sock)
  {

  	struct sock *sk;

  	mutex_lock(&econet_mutex);
  
  	sk = sock->sk;

  	if (!sk)

  		goto out_unlock;

  
  	econet_remove_socket(&econet_sklist, sk);
  
  	/*
  	 *	Now the socket is dead. No more input will appear.
  	 */
  
  	sk->sk_state_change(sk);	/* It is useless. Just for sanity. */

  	sock_orphan(sk);

  
  	/* Purge queues */
  
  	skb_queue_purge(&sk->sk_receive_queue);

  	if (sk_has_allocations(sk)) {

  		sk->sk_timer.data     = (unsigned long)sk;
  		sk->sk_timer.expires  = jiffies + HZ;
  		sk->sk_timer.function = econet_destroy_timer;
  		add_timer(&sk->sk_timer);

  
  		goto out_unlock;

  	}
  
  	sk_free(sk);

  
  out_unlock:
  	mutex_unlock(&econet_mutex);

  	return 0;
  }
  
  static struct proto econet_proto = {
  	.name	  = "ECONET",
  	.owner	  = THIS_MODULE,
  	.obj_size = sizeof(struct econet_sock),
  };
  
  /*
   *	Create an Econet socket
   */

  static int econet_create(struct net *net, struct socket *sock, int protocol,
  			 int kern)

  {
  	struct sock *sk;
  	struct econet_sock *eo;
  	int err;

  	if (!net_eq(net, &init_net))

  		return -EAFNOSUPPORT;

  	/* Econet only provides datagram services. */
  	if (sock->type != SOCK_DGRAM)
  		return -ESOCKTNOSUPPORT;
  
  	sock->state = SS_UNCONNECTED;
  
  	err = -ENOBUFS;

  	sk = sk_alloc(net, PF_ECONET, GFP_KERNEL, &econet_proto);

  	if (sk == NULL)
  		goto out;
  
  	sk->sk_reuse = 1;
  	sock->ops = &econet_ops;
  	sock_init_data(sock, sk);
  
  	eo = ec_sk(sk);
  	sock_reset_flag(sk, SOCK_ZAPPED);
  	sk->sk_family = PF_ECONET;
  	eo->num = protocol;
  
  	econet_insert_socket(&econet_sklist, sk);

  	return 0;

  out:
  	return err;
  }
  
  /*
   *	Handle Econet specific ioctls
   */
  
  static int ec_dev_ioctl(struct socket *sock, unsigned int cmd, void __user *arg)
  {
  	struct ifreq ifr;
  	struct ec_device *edev;
  	struct net_device *dev;
  	struct sockaddr_ec *sec;

  	int err;

  
  	/*
  	 *	Fetch the caller's info block into kernel space
  	 */
  
  	if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
  		return -EFAULT;

  	dev = dev_get_by_name(&init_net, ifr.ifr_name);
  	if (dev == NULL)

  		return -ENODEV;
  
  	sec = (struct sockaddr_ec *)&ifr.ifr_addr;

  	mutex_lock(&econet_mutex);
  
  	err = 0;
  	switch (cmd) {

  	case SIOCSIFADDR:

  		if (!capable(CAP_NET_ADMIN)) {
  			err = -EPERM;
  			break;
  		}

  		edev = dev->ec_ptr;

  		if (edev == NULL) {

  			/* Magic up a new one. */

  			edev = kzalloc(sizeof(struct ec_device), GFP_KERNEL);

  			if (edev == NULL) {

  				err = -ENOMEM;
  				break;

  			}

  			dev->ec_ptr = edev;

  		} else

  			net2dev_map[edev->net] = NULL;
  		edev->station = sec->addr.station;
  		edev->net = sec->addr.net;
  		net2dev_map[sec->addr.net] = dev;
  		if (!net2dev_map[0])
  			net2dev_map[0] = dev;

  		break;

  
  	case SIOCGIFADDR:
  		edev = dev->ec_ptr;

  		if (edev == NULL) {
  			err = -ENODEV;
  			break;

  		}
  		memset(sec, 0, sizeof(struct sockaddr_ec));
  		sec->addr.station = edev->station;
  		sec->addr.net = edev->net;
  		sec->sec_family = AF_ECONET;
  		dev_put(dev);
  		if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))

  			err = -EFAULT;
  		break;
  
  	default:
  		err = -EINVAL;
  		break;

  	}

  	mutex_unlock(&econet_mutex);

  	dev_put(dev);

  
  	return err;

  }
  
  /*
   *	Handle generic ioctls
   */

  static int econet_ioctl(struct socket *sock, unsigned int cmd,
  			unsigned long arg)

  {
  	struct sock *sk = sock->sk;
  	void __user *argp = (void __user *)arg;

  	switch (cmd) {
  	case SIOCGSTAMP:
  		return sock_get_timestamp(sk, argp);

  	case SIOCGSTAMPNS:
  		return sock_get_timestampns(sk, argp);

  	case SIOCSIFADDR:
  	case SIOCGIFADDR:
  		return ec_dev_ioctl(sock, cmd, argp);

  	}

  
  	return -ENOIOCTLCMD;

  }

  static const struct net_proto_family econet_family_ops = {

  	.family =	PF_ECONET,
  	.create =	econet_create,
  	.owner	=	THIS_MODULE,
  };

  static const struct proto_ops econet_ops = {

  	.family =	PF_ECONET,
  	.owner =	THIS_MODULE,
  	.release =	econet_release,
  	.bind =		econet_bind,
  	.connect =	sock_no_connect,
  	.socketpair =	sock_no_socketpair,
  	.accept =	sock_no_accept,

  	.getname =	econet_getname,

  	.poll =		datagram_poll,
  	.ioctl =	econet_ioctl,
  	.listen =	sock_no_listen,
  	.shutdown =	sock_no_shutdown,
  	.setsockopt =	sock_no_setsockopt,
  	.getsockopt =	sock_no_getsockopt,
  	.sendmsg =	econet_sendmsg,
  	.recvmsg =	econet_recvmsg,
  	.mmap =		sock_no_mmap,
  	.sendpage =	sock_no_sendpage,
  };

  #if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
  /*
   *	Find the listening socket, if any, for the given data.
   */
  
  static struct sock *ec_listening_socket(unsigned char port, unsigned char
  				 station, unsigned char net)
  {
  	struct sock *sk;
  	struct hlist_node *node;

  	spin_lock(&econet_lock);

  	sk_for_each(sk, node, &econet_sklist) {
  		struct econet_sock *opt = ec_sk(sk);

  		if ((opt->port == port || opt->port == 0) &&

  		    (opt->station == station || opt->station == 0) &&

  		    (opt->net == net || opt->net == 0)) {
  			sock_hold(sk);

  			goto found;

  		}

  	}
  	sk = NULL;
  found:

  	spin_unlock(&econet_lock);

  	return sk;
  }
  
  /*
   *	Queue a received packet for a socket.
   */
  
  static int ec_queue_packet(struct sock *sk, struct sk_buff *skb,
  			   unsigned char stn, unsigned char net,
  			   unsigned char cb, unsigned char port)
  {
  	struct ec_cb *eb = (struct ec_cb *)&skb->cb;
  	struct sockaddr_ec *sec = (struct sockaddr_ec *)&eb->sec;
  
  	memset(sec, 0, sizeof(struct sockaddr_ec));
  	sec->sec_family = AF_ECONET;
  	sec->type = ECTYPE_PACKET_RECEIVED;
  	sec->port = port;
  	sec->cb = cb;
  	sec->addr.net = net;
  	sec->addr.station = stn;
  
  	return sock_queue_rcv_skb(sk, skb);
  }
  #endif
  
  #ifdef CONFIG_ECONET_AUNUDP
  /*

   *	Send an AUN protocol response.

   */
  
  static void aun_send_response(__u32 addr, unsigned long seq, int code, int cb)
  {
  	struct sockaddr_in sin = {
  		.sin_family = AF_INET,
  		.sin_port = htons(AUN_PORT),
  		.sin_addr = {.s_addr = addr}
  	};
  	struct aunhdr ah = {.code = code, .cb = cb, .handle = seq};
  	struct kvec iov = {.iov_base = (void *)&ah, .iov_len = sizeof(ah)};
  	struct msghdr udpmsg;

  	udpmsg.msg_name = (void *)&sin;
  	udpmsg.msg_namelen = sizeof(sin);
  	udpmsg.msg_control = NULL;
  	udpmsg.msg_controllen = 0;

  	udpmsg.msg_flags = 0;

  
  	kernel_sendmsg(udpsock, &udpmsg, &iov, 1, sizeof(ah));
  }
  
  
  /*
   *	Handle incoming AUN packets.  Work out if anybody wants them,
   *	and send positive or negative acknowledgements as appropriate.
   */
  
  static void aun_incoming(struct sk_buff *skb, struct aunhdr *ah, size_t len)
  {

  	struct iphdr *ip = ip_hdr(skb);

  	unsigned char stn = ntohl(ip->saddr) & 0xff;

  	struct dst_entry *dst = skb_dst(skb);
  	struct ec_device *edev = NULL;

  	struct sock *sk = NULL;

  	struct sk_buff *newskb;

  
  	if (dst)
  		edev = dst->dev->ec_ptr;

  	if (!edev)

  		goto bad;

  	sk = ec_listening_socket(ah->port, stn, edev->net);
  	if (sk == NULL)

  		goto bad;		/* Nobody wants it */

  	newskb = alloc_skb((len - sizeof(struct aunhdr) + 15) & ~15,

  			   GFP_ATOMIC);

  	if (newskb == NULL) {
  		pr_debug("AUN: memory squeeze, dropping packet
  ");

  		/* Send nack and hope sender tries again */
  		goto bad;
  	}

  	memcpy(skb_put(newskb, len - sizeof(struct aunhdr)), (void *)(ah + 1),

  	       len - sizeof(struct aunhdr));

  	if (ec_queue_packet(sk, newskb, stn, edev->net, ah->cb, ah->port)) {

  		/* Socket is bankrupt. */
  		kfree_skb(newskb);
  		goto bad;
  	}
  
  	aun_send_response(ip->saddr, ah->handle, 3, 0);

  	sock_put(sk);

  	return;
  
  bad:
  	aun_send_response(ip->saddr, ah->handle, 4, 0);

  	if (sk)
  		sock_put(sk);

  }
  
  /*
   *	Handle incoming AUN transmit acknowledgements.  If the sequence
   *      number matches something in our backlog then kill it and tell
   *	the user.  If the remote took too long to reply then we may have
   *	dropped the packet already.
   */
  
  static void aun_tx_ack(unsigned long seq, int result)
  {
  	struct sk_buff *skb;
  	unsigned long flags;
  	struct ec_cb *eb;
  
  	spin_lock_irqsave(&aun_queue_lock, flags);

  	skb_queue_walk(&aun_queue, skb) {

  		eb = (struct ec_cb *)&skb->cb;
  		if (eb->seq == seq)
  			goto foundit;

  	}
  	spin_unlock_irqrestore(&aun_queue_lock, flags);

  	pr_debug("AUN: unknown sequence %ld
  ", seq);

  	return;
  
  foundit:
  	tx_result(skb->sk, eb->cookie, result);

  	skb_unlink(skb, &aun_queue);

  	spin_unlock_irqrestore(&aun_queue_lock, flags);
  	kfree_skb(skb);
  }
  
  /*
   *	Deal with received AUN frames - sort out what type of thing it is
   *	and hand it to the right function.
   */
  
  static void aun_data_available(struct sock *sk, int slen)
  {
  	int err;
  	struct sk_buff *skb;
  	unsigned char *data;
  	struct aunhdr *ah;

  	size_t len;
  
  	while ((skb = skb_recv_datagram(sk, 0, 1, &err)) == NULL) {
  		if (err == -EAGAIN) {

  			pr_err("AUN: no data available?!
  ");

  			return;
  		}

  		pr_debug("AUN: recvfrom() error %d
  ", -err);

  	}

  	data = skb_transport_header(skb) + sizeof(struct udphdr);

  	ah = (struct aunhdr *)data;
  	len = skb->len - sizeof(struct udphdr);

  	switch (ah->code) {

  	case 2:
  		aun_incoming(skb, ah, len);
  		break;
  	case 3:
  		aun_tx_ack(ah->handle, ECTYPE_TRANSMIT_OK);
  		break;
  	case 4:
  		aun_tx_ack(ah->handle, ECTYPE_TRANSMIT_NOT_LISTENING);
  		break;

  	default:

  		pr_debug("AUN: unknown packet type: %d
  ", data[0]);

  	}
  
  	skb_free_datagram(sk, skb);
  }
  
  /*
   *	Called by the timer to manage the AUN transmit queue.  If a packet
   *	was sent to a dead or nonexistent host then we will never get an
   *	acknowledgement back.  After a few seconds we need to spot this and
   *	drop the packet.
   */
  
  static void ab_cleanup(unsigned long h)
  {

  	struct sk_buff *skb, *n;

  	unsigned long flags;
  
  	spin_lock_irqsave(&aun_queue_lock, flags);

  	skb_queue_walk_safe(&aun_queue, skb, n) {

  		struct ec_cb *eb = (struct ec_cb *)&skb->cb;

  		if ((jiffies - eb->start) > eb->timeout) {

  			tx_result(skb->sk, eb->cookie,

  				  ECTYPE_TRANSMIT_NOT_PRESENT);

  			skb_unlink(skb, &aun_queue);

  			kfree_skb(skb);
  		}

  	}
  	spin_unlock_irqrestore(&aun_queue_lock, flags);

  	mod_timer(&ab_cleanup_timer, jiffies + (HZ * 2));

  }
  
  static int __init aun_udp_initialise(void)
  {
  	int error;
  	struct sockaddr_in sin;
  
  	skb_queue_head_init(&aun_queue);

  	setup_timer(&ab_cleanup_timer, ab_cleanup, 0);

  	ab_cleanup_timer.expires = jiffies + (HZ * 2);

  	add_timer(&ab_cleanup_timer);
  
  	memset(&sin, 0, sizeof(sin));
  	sin.sin_port = htons(AUN_PORT);
  
  	/* We can count ourselves lucky Acorn machines are too dim to
  	   speak IPv6. :-) */

  	error = sock_create_kern(PF_INET, SOCK_DGRAM, 0, &udpsock);
  	if (error < 0) {
  		pr_err("AUN: socket error %d
  ", -error);

  		return error;
  	}

  	udpsock->sk->sk_reuse = 1;
  	udpsock->sk->sk_allocation = GFP_ATOMIC; /* we're going to call it
  						    from interrupts */

  	error = udpsock->ops->bind(udpsock, (struct sockaddr *)&sin,

  				   sizeof(sin));
  	if (error < 0) {
  		pr_err("AUN: bind error %d
  ", -error);

  		goto release;
  	}
  
  	udpsock->sk->sk_data_ready = aun_data_available;
  
  	return 0;
  
  release:
  	sock_release(udpsock);
  	udpsock = NULL;
  	return error;
  }
  #endif
  
  #ifdef CONFIG_ECONET_NATIVE
  
  /*
   *	Receive an Econet frame from a device.
   */

  static int econet_rcv(struct sk_buff *skb, struct net_device *dev,
  		      struct packet_type *pt, struct net_device *orig_dev)

  {
  	struct ec_framehdr *hdr;

  	struct sock *sk = NULL;

  	struct ec_device *edev = dev->ec_ptr;

  	if (!net_eq(dev_net(dev), &init_net))

  		goto drop;

  	if (skb->pkt_type == PACKET_OTHERHOST)
  		goto drop;
  
  	if (!edev)
  		goto drop;

  	skb = skb_share_check(skb, GFP_ATOMIC);
  	if (skb == NULL)

  		return NET_RX_DROP;
  
  	if (!pskb_may_pull(skb, sizeof(struct ec_framehdr)))
  		goto drop;

  	hdr = (struct ec_framehdr *)skb->data;

  
  	/* First check for encapsulated IP */
  	if (hdr->port == EC_PORT_IP) {
  		skb->protocol = htons(ETH_P_IP);
  		skb_pull(skb, sizeof(struct ec_framehdr));
  		netif_rx(skb);

  		return NET_RX_SUCCESS;

  	}
  
  	sk = ec_listening_socket(hdr->port, hdr->src_stn, hdr->src_net);
  	if (!sk)
  		goto drop;
  
  	if (ec_queue_packet(sk, skb, edev->net, hdr->src_stn, hdr->cb,
  			    hdr->port))
  		goto drop;

  	sock_put(sk);

  	return NET_RX_SUCCESS;

  
  drop:

  	if (sk)
  		sock_put(sk);

  	kfree_skb(skb);
  	return NET_RX_DROP;
  }

  static struct packet_type econet_packet_type __read_mostly = {

  	.type =	cpu_to_be16(ETH_P_ECONET),
  	.func =	econet_rcv,

  };
  
  static void econet_hw_initialise(void)
  {
  	dev_add_pack(&econet_packet_type);
  }
  
  #endif

  static int econet_notifier(struct notifier_block *this, unsigned long msg,
  			   void *data)

  {

  	struct net_device *dev = data;

  	struct ec_device *edev;

  	if (!net_eq(dev_net(dev), &init_net))

  		return NOTIFY_DONE;

  	switch (msg) {
  	case NETDEV_UNREGISTER:
  		/* A device has gone down - kill any data we hold for it. */
  		edev = dev->ec_ptr;

  		if (edev) {

  			if (net2dev_map[0] == dev)
  				net2dev_map[0] = NULL;
  			net2dev_map[edev->net] = NULL;
  			kfree(edev);
  			dev->ec_ptr = NULL;
  		}
  		break;
  	}
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block econet_netdev_notifier = {

  	.notifier_call = econet_notifier,

  };
  
  static void __exit econet_proto_exit(void)
  {
  #ifdef CONFIG_ECONET_AUNUDP
  	del_timer(&ab_cleanup_timer);
  	if (udpsock)
  		sock_release(udpsock);
  #endif
  	unregister_netdevice_notifier(&econet_netdev_notifier);

  #ifdef CONFIG_ECONET_NATIVE
  	dev_remove_pack(&econet_packet_type);
  #endif

  	sock_unregister(econet_family_ops.family);
  	proto_unregister(&econet_proto);
  }
  
  static int __init econet_proto_init(void)
  {
  	int err = proto_register(&econet_proto, 0);
  
  	if (err != 0)
  		goto out;
  	sock_register(&econet_family_ops);
  #ifdef CONFIG_ECONET_AUNUDP

  	aun_udp_initialise();
  #endif
  #ifdef CONFIG_ECONET_NATIVE
  	econet_hw_initialise();
  #endif
  	register_netdevice_notifier(&econet_netdev_notifier);
  out:
  	return err;
  }
  
  module_init(econet_proto_init);
  module_exit(econet_proto_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_NETPROTO(PF_ECONET);