text: /*
   *	DDP:	An implementation of the AppleTalk DDP protocol for
   *		Ethernet 'ELAP'.
   *
   *		Alan Cox  <alan@lxorguk.ukuu.org.uk>
   *
   *		With more than a little assistance from
   *
   *		Wesley Craig <netatalk@umich.edu>
   *
   *	Fixes:
   *		Neil Horman		:	Added missing device ioctls
   *		Michael Callahan	:	Made routing work
   *		Wesley Craig		:	Fix probing to listen to a
   *						passed node id.
   *		Alan Cox		:	Added send/recvmsg support
   *		Alan Cox		:	Moved at. to protinfo in
   *						socket.
   *		Alan Cox		:	Added firewall hooks.
   *		Alan Cox		:	Supports new ARPHRD_LOOPBACK
   *		Christer Weinigel	: 	Routing and /proc fixes.
   *		Bradford Johnson	:	LocalTalk.
   *		Tom Dyas		:	Module support.
   *		Alan Cox		:	Hooks for PPP (based on the
   *						LocalTalk hook).
   *		Alan Cox		:	Posix bits
   *		Alan Cox/Mike Freeman	:	Possible fix to NBP problems
   *		Bradford Johnson	:	IP-over-DDP (experimental)
   *		Jay Schulist		:	Moved IP-over-DDP to its own
   *						driver file. (ipddp.c & ipddp.h)
   *		Jay Schulist		:	Made work as module with
   *						AppleTalk drivers, cleaned it.
   *		Rob Newberry		:	Added proxy AARP and AARP
   *						procfs, moved probing to AARP
   *						module.
   *              Adrian Sun/
   *              Michael Zuelsdorff      :       fix for net.0 packets. don't
   *                                              allow illegal ether/tokentalk
   *                                              port assignment. we lose a
   *                                              valid localtalk port as a
   *                                              result.
   *		Arnaldo C. de Melo	:	Cleanup, in preparation for
   *						shared skb support 8)
   *		Arnaldo C. de Melo	:	Move proc stuff to atalk_proc.c,
   *						use seq_file
   *
   *		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/capability.h>
  #include <linux/module.h>
  #include <linux/if_arp.h>
  #include <linux/termios.h>	/* For TIOCOUTQ/INQ */
  #include <linux/compat.h>
  #include <linux/slab.h>
  #include <net/datalink.h>
  #include <net/psnap.h>
  #include <net/sock.h>
  #include <net/tcp_states.h>
  #include <net/route.h>
  #include <linux/atalk.h>
  #include <linux/highmem.h>
  
  struct datalink_proto *ddp_dl, *aarp_dl;
  static const struct proto_ops atalk_dgram_ops;
  
  /**************************************************************************\
  *                                                                          *
  * Handlers for the socket list.                                            *
  *                                                                          *
  \**************************************************************************/
  
  HLIST_HEAD(atalk_sockets);
  DEFINE_RWLOCK(atalk_sockets_lock);
  
  static inline void __atalk_insert_socket(struct sock *sk)
  {
  	sk_add_node(sk, &atalk_sockets);
  }
  
  static inline void atalk_remove_socket(struct sock *sk)
  {
  	write_lock_bh(&atalk_sockets_lock);
  	sk_del_node_init(sk);
  	write_unlock_bh(&atalk_sockets_lock);
  }
  
  static struct sock *atalk_search_socket(struct sockaddr_at *to,
  					struct atalk_iface *atif)
  {
  	struct sock *s;
  
  	read_lock_bh(&atalk_sockets_lock);
  	sk_for_each(s, &atalk_sockets) {
  		struct atalk_sock *at = at_sk(s);
  
  		if (to->sat_port != at->src_port)
  			continue;
  
  		if (to->sat_addr.s_net == ATADDR_ANYNET &&
  		    to->sat_addr.s_node == ATADDR_BCAST)
  			goto found;
  
  		if (to->sat_addr.s_net == at->src_net &&
  		    (to->sat_addr.s_node == at->src_node ||
  		     to->sat_addr.s_node == ATADDR_BCAST ||
  		     to->sat_addr.s_node == ATADDR_ANYNODE))
  			goto found;
  
  		/* XXXX.0 -- we got a request for this router. make sure
  		 * that the node is appropriately set. */
  		if (to->sat_addr.s_node == ATADDR_ANYNODE &&
  		    to->sat_addr.s_net != ATADDR_ANYNET &&
  		    atif->address.s_node == at->src_node) {
  			to->sat_addr.s_node = atif->address.s_node;
  			goto found;
  		}
  	}
  	s = NULL;
  found:
  	read_unlock_bh(&atalk_sockets_lock);
  	return s;
  }
  
  /**
   * atalk_find_or_insert_socket - Try to find a socket matching ADDR
   * @sk: socket to insert in the list if it is not there already
   * @sat: address to search for
   *
   * Try to find a socket matching ADDR in the socket list, if found then return
   * it. If not, insert SK into the socket list.
   *
   * This entire operation must execute atomically.
   */
  static struct sock *atalk_find_or_insert_socket(struct sock *sk,
  						struct sockaddr_at *sat)
  {
  	struct sock *s;
  	struct atalk_sock *at;
  
  	write_lock_bh(&atalk_sockets_lock);
  	sk_for_each(s, &atalk_sockets) {
  		at = at_sk(s);
  
  		if (at->src_net == sat->sat_addr.s_net &&
  		    at->src_node == sat->sat_addr.s_node &&
  		    at->src_port == sat->sat_port)
  			goto found;
  	}
  	s = NULL;
  	__atalk_insert_socket(sk); /* Wheee, it's free, assign and insert. */
  found:
  	write_unlock_bh(&atalk_sockets_lock);
  	return s;
  }
  
  static void atalk_destroy_timer(unsigned long data)
  {
  	struct sock *sk = (struct sock *)data;
  
  	if (sk_has_allocations(sk)) {
  		sk->sk_timer.expires = jiffies + SOCK_DESTROY_TIME;
  		add_timer(&sk->sk_timer);
  	} else
  		sock_put(sk);
  }
  
  static inline void atalk_destroy_socket(struct sock *sk)
  {
  	atalk_remove_socket(sk);
  	skb_queue_purge(&sk->sk_receive_queue);
  
  	if (sk_has_allocations(sk)) {
  		setup_timer(&sk->sk_timer, atalk_destroy_timer,
  				(unsigned long)sk);
  		sk->sk_timer.expires	= jiffies + SOCK_DESTROY_TIME;
  		add_timer(&sk->sk_timer);
  	} else
  		sock_put(sk);
  }
  
  /**************************************************************************\
  *                                                                          *
  * Routing tables for the AppleTalk socket layer.                           *
  *                                                                          *
  \**************************************************************************/
  
  /* Anti-deadlock ordering is atalk_routes_lock --> iface_lock -DaveM */
  struct atalk_route *atalk_routes;
  DEFINE_RWLOCK(atalk_routes_lock);
  
  struct atalk_iface *atalk_interfaces;
  DEFINE_RWLOCK(atalk_interfaces_lock);
  
  /* For probing devices or in a routerless network */
  struct atalk_route atrtr_default;
  
  /* AppleTalk interface control */
  /*
   * Drop a device. Doesn't drop any of its routes - that is the caller's
   * problem. Called when we down the interface or delete the address.
   */
  static void atif_drop_device(struct net_device *dev)
  {
  	struct atalk_iface **iface = &atalk_interfaces;
  	struct atalk_iface *tmp;
  
  	write_lock_bh(&atalk_interfaces_lock);
  	while ((tmp = *iface) != NULL) {
  		if (tmp->dev == dev) {
  			*iface = tmp->next;
  			dev_put(dev);
  			kfree(tmp);
  			dev->atalk_ptr = NULL;
  		} else
  			iface = &tmp->next;
  	}
  	write_unlock_bh(&atalk_interfaces_lock);
  }
  
  static struct atalk_iface *atif_add_device(struct net_device *dev,
  					   struct atalk_addr *sa)
  {
  	struct atalk_iface *iface = kzalloc(sizeof(*iface), GFP_KERNEL);
  
  	if (!iface)
  		goto out;
  
  	dev_hold(dev);
  	iface->dev = dev;
  	dev->atalk_ptr = iface;
  	iface->address = *sa;
  	iface->status = 0;
  
  	write_lock_bh(&atalk_interfaces_lock);
  	iface->next = atalk_interfaces;
  	atalk_interfaces = iface;
  	write_unlock_bh(&atalk_interfaces_lock);
  out:
  	return iface;
  }
  
  /* Perform phase 2 AARP probing on our tentative address */
  static int atif_probe_device(struct atalk_iface *atif)
  {
  	int netrange = ntohs(atif->nets.nr_lastnet) -
  			ntohs(atif->nets.nr_firstnet) + 1;
  	int probe_net = ntohs(atif->address.s_net);
  	int probe_node = atif->address.s_node;
  	int netct, nodect;
  
  	/* Offset the network we start probing with */
  	if (probe_net == ATADDR_ANYNET) {
  		probe_net = ntohs(atif->nets.nr_firstnet);
  		if (netrange)
  			probe_net += jiffies % netrange;
  	}
  	if (probe_node == ATADDR_ANYNODE)
  		probe_node = jiffies & 0xFF;
  
  	/* Scan the networks */
  	atif->status |= ATIF_PROBE;
  	for (netct = 0; netct <= netrange; netct++) {
  		/* Sweep the available nodes from a given start */
  		atif->address.s_net = htons(probe_net);
  		for (nodect = 0; nodect < 256; nodect++) {
  			atif->address.s_node = (nodect + probe_node) & 0xFF;
  			if (atif->address.s_node > 0 &&
  			    atif->address.s_node < 254) {
  				/* Probe a proposed address */
  				aarp_probe_network(atif);
  
  				if (!(atif->status & ATIF_PROBE_FAIL)) {
  					atif->status &= ~ATIF_PROBE;
  					return 0;
  				}
  			}
  			atif->status &= ~ATIF_PROBE_FAIL;
  		}
  		probe_net++;
  		if (probe_net > ntohs(atif->nets.nr_lastnet))
  			probe_net = ntohs(atif->nets.nr_firstnet);
  	}
  	atif->status &= ~ATIF_PROBE;
  
  	return -EADDRINUSE;	/* Network is full... */
  }
  
  
  /* Perform AARP probing for a proxy address */
  static int atif_proxy_probe_device(struct atalk_iface *atif,
  				   struct atalk_addr *proxy_addr)
  {
  	int netrange = ntohs(atif->nets.nr_lastnet) -
  			ntohs(atif->nets.nr_firstnet) + 1;
  	/* we probe the interface's network */
  	int probe_net = ntohs(atif->address.s_net);
  	int probe_node = ATADDR_ANYNODE;	    /* we'll take anything */
  	int netct, nodect;
  
  	/* Offset the network we start probing with */
  	if (probe_net == ATADDR_ANYNET) {
  		probe_net = ntohs(atif->nets.nr_firstnet);
  		if (netrange)
  			probe_net += jiffies % netrange;
  	}
  
  	if (probe_node == ATADDR_ANYNODE)
  		probe_node = jiffies & 0xFF;
  
  	/* Scan the networks */
  	for (netct = 0; netct <= netrange; netct++) {
  		/* Sweep the available nodes from a given start */
  		proxy_addr->s_net = htons(probe_net);
  		for (nodect = 0; nodect < 256; nodect++) {
  			proxy_addr->s_node = (nodect + probe_node) & 0xFF;
  			if (proxy_addr->s_node > 0 &&
  			    proxy_addr->s_node < 254) {
  				/* Tell AARP to probe a proposed address */
  				int ret = aarp_proxy_probe_network(atif,
  								    proxy_addr);
  
  				if (ret != -EADDRINUSE)
  					return ret;
  			}
  		}
  		probe_net++;
  		if (probe_net > ntohs(atif->nets.nr_lastnet))
  			probe_net = ntohs(atif->nets.nr_firstnet);
  	}
  
  	return -EADDRINUSE;	/* Network is full... */
  }
  
  
  struct atalk_addr *atalk_find_dev_addr(struct net_device *dev)
  {
  	struct atalk_iface *iface = dev->atalk_ptr;
  	return iface ? &iface->address : NULL;
  }
  
  static struct atalk_addr *atalk_find_primary(void)
  {
  	struct atalk_iface *fiface = NULL;
  	struct atalk_addr *retval;
  	struct atalk_iface *iface;
  
  	/*
  	 * Return a point-to-point interface only if
  	 * there is no non-ptp interface available.
  	 */
  	read_lock_bh(&atalk_interfaces_lock);
  	for (iface = atalk_interfaces; iface; iface = iface->next) {
  		if (!fiface && !(iface->dev->flags & IFF_LOOPBACK))
  			fiface = iface;
  		if (!(iface->dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) {
  			retval = &iface->address;
  			goto out;
  		}
  	}
  
  	if (fiface)
  		retval = &fiface->address;
  	else if (atalk_interfaces)
  		retval = &atalk_interfaces->address;
  	else
  		retval = NULL;
  out:
  	read_unlock_bh(&atalk_interfaces_lock);
  	return retval;
  }
  
  /*
   * Find a match for 'any network' - ie any of our interfaces with that
   * node number will do just nicely.
   */
  static struct atalk_iface *atalk_find_anynet(int node, struct net_device *dev)
  {
  	struct atalk_iface *iface = dev->atalk_ptr;
  
  	if (!iface || iface->status & ATIF_PROBE)
  		goto out_err;
  
  	if (node != ATADDR_BCAST &&
  	    iface->address.s_node != node &&
  	    node != ATADDR_ANYNODE)
  		goto out_err;
  out:
  	return iface;
  out_err:
  	iface = NULL;
  	goto out;
  }
  
  /* Find a match for a specific network:node pair */
  static struct atalk_iface *atalk_find_interface(__be16 net, int node)
  {
  	struct atalk_iface *iface;
  
  	read_lock_bh(&atalk_interfaces_lock);
  	for (iface = atalk_interfaces; iface; iface = iface->next) {
  		if ((node == ATADDR_BCAST ||
  		     node == ATADDR_ANYNODE ||
  		     iface->address.s_node == node) &&
  		    iface->address.s_net == net &&
  		    !(iface->status & ATIF_PROBE))
  			break;
  
  		/* XXXX.0 -- net.0 returns the iface associated with net */
  		if (node == ATADDR_ANYNODE && net != ATADDR_ANYNET &&
  		    ntohs(iface->nets.nr_firstnet) <= ntohs(net) &&
  		    ntohs(net) <= ntohs(iface->nets.nr_lastnet))
  			break;
  	}
  	read_unlock_bh(&atalk_interfaces_lock);
  	return iface;
  }
  
  
  /*
   * Find a route for an AppleTalk packet. This ought to get cached in
   * the socket (later on...). We know about host routes and the fact
   * that a route must be direct to broadcast.
   */
  static struct atalk_route *atrtr_find(struct atalk_addr *target)
  {
  	/*
  	 * we must search through all routes unless we find a
  	 * host route, because some host routes might overlap
  	 * network routes
  	 */
  	struct atalk_route *net_route = NULL;
  	struct atalk_route *r;
  
  	read_lock_bh(&atalk_routes_lock);
  	for (r = atalk_routes; r; r = r->next) {
  		if (!(r->flags & RTF_UP))
  			continue;
  
  		if (r->target.s_net == target->s_net) {
  			if (r->flags & RTF_HOST) {
  				/*
  				 * if this host route is for the target,
  				 * the we're done
  				 */
  				if (r->target.s_node == target->s_node)
  					goto out;
  			} else
  				/*
  				 * this route will work if there isn't a
  				 * direct host route, so cache it
  				 */
  				net_route = r;
  		}
  	}
  
  	/*
  	 * if we found a network route but not a direct host
  	 * route, then return it
  	 */
  	if (net_route)
  		r = net_route;
  	else if (atrtr_default.dev)
  		r = &atrtr_default;
  	else /* No route can be found */
  		r = NULL;
  out:
  	read_unlock_bh(&atalk_routes_lock);
  	return r;
  }
  
  
  /*
   * Given an AppleTalk network, find the device to use. This can be
   * a simple lookup.
   */
  struct net_device *atrtr_get_dev(struct atalk_addr *sa)
  {
  	struct atalk_route *atr = atrtr_find(sa);
  	return atr ? atr->dev : NULL;
  }
  
  /* Set up a default router */
  static void atrtr_set_default(struct net_device *dev)
  {
  	atrtr_default.dev	     = dev;
  	atrtr_default.flags	     = RTF_UP;
  	atrtr_default.gateway.s_net  = htons(0);
  	atrtr_default.gateway.s_node = 0;
  }
  
  /*
   * Add a router. Basically make sure it looks valid and stuff the
   * entry in the list. While it uses netranges we always set them to one
   * entry to work like netatalk.
   */
  static int atrtr_create(struct rtentry *r, struct net_device *devhint)
  {
  	struct sockaddr_at *ta = (struct sockaddr_at *)&r->rt_dst;
  	struct sockaddr_at *ga = (struct sockaddr_at *)&r->rt_gateway;
  	struct atalk_route *rt;
  	struct atalk_iface *iface, *riface;
  	int retval = -EINVAL;
  
  	/*
  	 * Fixme: Raise/Lower a routing change semaphore for these
  	 * operations.
  	 */
  
  	/* Validate the request */
  	if (ta->sat_family != AF_APPLETALK ||
  	    (!devhint && ga->sat_family != AF_APPLETALK))
  		goto out;
  
  	/* Now walk the routing table and make our decisions */
  	write_lock_bh(&atalk_routes_lock);
  	for (rt = atalk_routes; rt; rt = rt->next) {
  		if (r->rt_flags != rt->flags)
  			continue;
  
  		if (ta->sat_addr.s_net == rt->target.s_net) {
  			if (!(rt->flags & RTF_HOST))
  				break;
  			if (ta->sat_addr.s_node == rt->target.s_node)
  				break;
  		}
  	}
  
  	if (!devhint) {
  		riface = NULL;
  
  		read_lock_bh(&atalk_interfaces_lock);
  		for (iface = atalk_interfaces; iface; iface = iface->next) {
  			if (!riface &&
  			    ntohs(ga->sat_addr.s_net) >=
  					ntohs(iface->nets.nr_firstnet) &&
  			    ntohs(ga->sat_addr.s_net) <=
  					ntohs(iface->nets.nr_lastnet))
  				riface = iface;
  
  			if (ga->sat_addr.s_net == iface->address.s_net &&
  			    ga->sat_addr.s_node == iface->address.s_node)
  				riface = iface;
  		}
  		read_unlock_bh(&atalk_interfaces_lock);
  
  		retval = -ENETUNREACH;
  		if (!riface)
  			goto out_unlock;
  
  		devhint = riface->dev;
  	}
  
  	if (!rt) {
  		rt = kzalloc(sizeof(*rt), GFP_ATOMIC);
  
  		retval = -ENOBUFS;
  		if (!rt)
  			goto out_unlock;
  
  		rt->next = atalk_routes;
  		atalk_routes = rt;
  	}
  
  	/* Fill in the routing entry */
  	rt->target  = ta->sat_addr;
  	dev_hold(devhint);
  	rt->dev     = devhint;
  	rt->flags   = r->rt_flags;
  	rt->gateway = ga->sat_addr;
  
  	retval = 0;
  out_unlock:
  	write_unlock_bh(&atalk_routes_lock);
  out:
  	return retval;
  }
  
  /* Delete a route. Find it and discard it */
  static int atrtr_delete(struct atalk_addr *addr)
  {
  	struct atalk_route **r = &atalk_routes;
  	int retval = 0;
  	struct atalk_route *tmp;
  
  	write_lock_bh(&atalk_routes_lock);
  	while ((tmp = *r) != NULL) {
  		if (tmp->target.s_net == addr->s_net &&
  		    (!(tmp->flags&RTF_GATEWAY) ||
  		     tmp->target.s_node == addr->s_node)) {
  			*r = tmp->next;
  			dev_put(tmp->dev);
  			kfree(tmp);
  			goto out;
  		}
  		r = &tmp->next;
  	}
  	retval = -ENOENT;
  out:
  	write_unlock_bh(&atalk_routes_lock);
  	return retval;
  }
  
  /*
   * Called when a device is downed. Just throw away any routes
   * via it.
   */
  static void atrtr_device_down(struct net_device *dev)
  {
  	struct atalk_route **r = &atalk_routes;
  	struct atalk_route *tmp;
  
  	write_lock_bh(&atalk_routes_lock);
  	while ((tmp = *r) != NULL) {
  		if (tmp->dev == dev) {
  			*r = tmp->next;
  			dev_put(dev);
  			kfree(tmp);
  		} else
  			r = &tmp->next;
  	}
  	write_unlock_bh(&atalk_routes_lock);
  
  	if (atrtr_default.dev == dev)
  		atrtr_set_default(NULL);
  }
  
  /* Actually down the interface */
  static inline void atalk_dev_down(struct net_device *dev)
  {
  	atrtr_device_down(dev);	/* Remove all routes for the device */
  	aarp_device_down(dev);	/* Remove AARP entries for the device */
  	atif_drop_device(dev);	/* Remove the device */
  }
  
  /*
   * A device event has occurred. Watch for devices going down and
   * delete our use of them (iface and route).
   */
  static int ddp_device_event(struct notifier_block *this, unsigned long event,
  			    void *ptr)
  {
  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  
  	if (!net_eq(dev_net(dev), &init_net))
  		return NOTIFY_DONE;
  
  	if (event == NETDEV_DOWN)
  		/* Discard any use of this */
  		atalk_dev_down(dev);
  
  	return NOTIFY_DONE;
  }
  
  /* ioctl calls. Shouldn't even need touching */
  /* Device configuration ioctl calls */
  static int atif_ioctl(int cmd, void __user *arg)
  {
  	static char aarp_mcast[6] = { 0x09, 0x00, 0x00, 0xFF, 0xFF, 0xFF };
  	struct ifreq atreq;
  	struct atalk_netrange *nr;
  	struct sockaddr_at *sa;
  	struct net_device *dev;
  	struct atalk_iface *atif;
  	int ct;
  	int limit;
  	struct rtentry rtdef;
  	int add_route;
  
  	if (copy_from_user(&atreq, arg, sizeof(atreq)))
  		return -EFAULT;
  
  	dev = __dev_get_by_name(&init_net, atreq.ifr_name);
  	if (!dev)
  		return -ENODEV;
  
  	sa = (struct sockaddr_at *)&atreq.ifr_addr;
  	atif = atalk_find_dev(dev);
  
  	switch (cmd) {
  	case SIOCSIFADDR:
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		if (sa->sat_family != AF_APPLETALK)
  			return -EINVAL;
  		if (dev->type != ARPHRD_ETHER &&
  		    dev->type != ARPHRD_LOOPBACK &&
  		    dev->type != ARPHRD_LOCALTLK &&
  		    dev->type != ARPHRD_PPP)
  			return -EPROTONOSUPPORT;
  
  		nr = (struct atalk_netrange *)&sa->sat_zero[0];
  		add_route = 1;
  
  		/*
  		 * if this is a point-to-point iface, and we already
  		 * have an iface for this AppleTalk address, then we
  		 * should not add a route
  		 */
  		if ((dev->flags & IFF_POINTOPOINT) &&
  		    atalk_find_interface(sa->sat_addr.s_net,
  					 sa->sat_addr.s_node)) {
  			printk(KERN_DEBUG "AppleTalk: point-to-point "
  			       "interface added with "
  			       "existing address\n");
  			add_route = 0;
  		}
  
  		/*
  		 * Phase 1 is fine on LocalTalk but we don't do
  		 * EtherTalk phase 1. Anyone wanting to add it go ahead.
  		 */
  		if (dev->type == ARPHRD_ETHER && nr->nr_phase != 2)
  			return -EPROTONOSUPPORT;
  		if (sa->sat_addr.s_node == ATADDR_BCAST ||
  		    sa->sat_addr.s_node == 254)
  			return -EINVAL;
  		if (atif) {
  			/* Already setting address */
  			if (atif->status & ATIF_PROBE)
  				return -EBUSY;
  
  			atif->address.s_net  = sa->sat_addr.s_net;
  			atif->address.s_node = sa->sat_addr.s_node;
  			atrtr_device_down(dev);	/* Flush old routes */
  		} else {
  			atif = atif_add_device(dev, &sa->sat_addr);
  			if (!atif)
  				return -ENOMEM;
  		}
  		atif->nets = *nr;
  
  		/*
  		 * Check if the chosen address is used. If so we
  		 * error and atalkd will try another.
  		 */
  
  		if (!(dev->flags & IFF_LOOPBACK) &&
  		    !(dev->flags & IFF_POINTOPOINT) &&
  		    atif_probe_device(atif) < 0) {
  			atif_drop_device(dev);
  			return -EADDRINUSE;
  		}
  
  		/* Hey it worked - add the direct routes */
  		sa = (struct sockaddr_at *)&rtdef.rt_gateway;
  		sa->sat_family = AF_APPLETALK;
  		sa->sat_addr.s_net  = atif->address.s_net;
  		sa->sat_addr.s_node = atif->address.s_node;
  		sa = (struct sockaddr_at *)&rtdef.rt_dst;
  		rtdef.rt_flags = RTF_UP;
  		sa->sat_family = AF_APPLETALK;
  		sa->sat_addr.s_node = ATADDR_ANYNODE;
  		if (dev->flags & IFF_LOOPBACK ||
  		    dev->flags & IFF_POINTOPOINT)
  			rtdef.rt_flags |= RTF_HOST;
  
  		/* Routerless initial state */
  		if (nr->nr_firstnet == htons(0) &&
  		    nr->nr_lastnet == htons(0xFFFE)) {
  			sa->sat_addr.s_net = atif->address.s_net;
  			atrtr_create(&rtdef, dev);
  			atrtr_set_default(dev);
  		} else {
  			limit = ntohs(nr->nr_lastnet);
  			if (limit - ntohs(nr->nr_firstnet) > 4096) {
  				printk(KERN_WARNING "Too many routes/"
  				       "iface.\n");
  				return -EINVAL;
  			}
  			if (add_route)
  				for (ct = ntohs(nr->nr_firstnet);
  				     ct <= limit; ct++) {
  					sa->sat_addr.s_net = htons(ct);
  					atrtr_create(&rtdef, dev);
  				}
  		}
  		dev_mc_add_global(dev, aarp_mcast);
  		return 0;
  
  	case SIOCGIFADDR:
  		if (!atif)
  			return -EADDRNOTAVAIL;
  
  		sa->sat_family = AF_APPLETALK;
  		sa->sat_addr = atif->address;
  		break;
  
  	case SIOCGIFBRDADDR:
  		if (!atif)
  			return -EADDRNOTAVAIL;
  
  		sa->sat_family = AF_APPLETALK;
  		sa->sat_addr.s_net = atif->address.s_net;
  		sa->sat_addr.s_node = ATADDR_BCAST;
  		break;
  
  	case SIOCATALKDIFADDR:
  	case SIOCDIFADDR:
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		if (sa->sat_family != AF_APPLETALK)
  			return -EINVAL;
  		atalk_dev_down(dev);
  		break;
  
  	case SIOCSARP:
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		if (sa->sat_family != AF_APPLETALK)
  			return -EINVAL;
  		/*
  		 * for now, we only support proxy AARP on ELAP;
  		 * we should be able to do it for LocalTalk, too.
  		 */
  		if (dev->type != ARPHRD_ETHER)
  			return -EPROTONOSUPPORT;
  
  		/*
  		 * atif points to the current interface on this network;
  		 * we aren't concerned about its current status (at
  		 * least for now), but it has all the settings about
  		 * the network we're going to probe. Consequently, it
  		 * must exist.
  		 */
  		if (!atif)
  			return -EADDRNOTAVAIL;
  
  		nr = (struct atalk_netrange *)&(atif->nets);
  		/*
  		 * Phase 1 is fine on Localtalk but we don't do
  		 * Ethertalk phase 1. Anyone wanting to add it go ahead.
  		 */
  		if (dev->type == ARPHRD_ETHER && nr->nr_phase != 2)
  			return -EPROTONOSUPPORT;
  
  		if (sa->sat_addr.s_node == ATADDR_BCAST ||
  		    sa->sat_addr.s_node == 254)
  			return -EINVAL;
  
  		/*
  		 * Check if the chosen address is used. If so we
  		 * error and ATCP will try another.
  		 */
  		if (atif_proxy_probe_device(atif, &(sa->sat_addr)) < 0)
  			return -EADDRINUSE;
  
  		/*
  		 * We now have an address on the local network, and
  		 * the AARP code will defend it for us until we take it
  		 * down. We don't set up any routes right now, because
  		 * ATCP will install them manually via SIOCADDRT.
  		 */
  		break;
  
  	case SIOCDARP:
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		if (sa->sat_family != AF_APPLETALK)
  			return -EINVAL;
  		if (!atif)
  			return -EADDRNOTAVAIL;
  
  		/* give to aarp module to remove proxy entry */
  		aarp_proxy_remove(atif->dev, &(sa->sat_addr));
  		return 0;
  	}
  
  	return copy_to_user(arg, &atreq, sizeof(atreq)) ? -EFAULT : 0;
  }
  
  /* Routing ioctl() calls */
  static int atrtr_ioctl(unsigned int cmd, void __user *arg)
  {
  	struct rtentry rt;
  
  	if (copy_from_user(&rt, arg, sizeof(rt)))
  		return -EFAULT;
  
  	switch (cmd) {
  	case SIOCDELRT:
  		if (rt.rt_dst.sa_family != AF_APPLETALK)
  			return -EINVAL;
  		return atrtr_delete(&((struct sockaddr_at *)
  				      &rt.rt_dst)->sat_addr);
  
  	case SIOCADDRT: {
  		struct net_device *dev = NULL;
  		if (rt.rt_dev) {
  			char name[IFNAMSIZ];
  			if (copy_from_user(name, rt.rt_dev, IFNAMSIZ-1))
  				return -EFAULT;
  			name[IFNAMSIZ-1] = '\0';
  			dev = __dev_get_by_name(&init_net, name);
  			if (!dev)
  				return -ENODEV;
  		}
  		return atrtr_create(&rt, dev);
  	}
  	}
  	return -EINVAL;
  }
  
  /**************************************************************************\
  *                                                                          *
  * Handling for system calls applied via the various interfaces to an       *
  * AppleTalk socket object.                                                 *
  *                                                                          *
  \**************************************************************************/
  
  /*
   * Checksum: This is 'optional'. It's quite likely also a good
   * candidate for assembler hackery 8)
   */
  static unsigned long atalk_sum_partial(const unsigned char *data,
  				       int len, unsigned long sum)
  {
  	/* This ought to be unwrapped neatly. I'll trust gcc for now */
  	while (len--) {
  		sum += *data++;
  		sum = rol16(sum, 1);
  	}
  	return sum;
  }
  
  /*  Checksum skb data --  similar to skb_checksum  */
  static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset,
  				   int len, unsigned long sum)
  {
  	int start = skb_headlen(skb);
  	struct sk_buff *frag_iter;
  	int i, copy;
  
  	/* checksum stuff in header space */
  	if ((copy = start - offset) > 0) {
  		if (copy > len)
  			copy = len;
  		sum = atalk_sum_partial(skb->data + offset, copy, sum);
  		if ((len -= copy) == 0)
  			return sum;
  
  		offset += copy;
  	}
  
  	/* checksum stuff in frags */
  	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
  		int end;
  		const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
  		WARN_ON(start > offset + len);
  
  		end = start + skb_frag_size(frag);
  		if ((copy = end - offset) > 0) {
  			u8 *vaddr;
  
  			if (copy > len)
  				copy = len;
  			vaddr = kmap_atomic(skb_frag_page(frag));
  			sum = atalk_sum_partial(vaddr + frag->page_offset +
  						  offset - start, copy, sum);
  			kunmap_atomic(vaddr);
  
  			if (!(len -= copy))
  				return sum;
  			offset += copy;
  		}
  		start = end;
  	}
  
  	skb_walk_frags(skb, frag_iter) {
  		int end;
  
  		WARN_ON(start > offset + len);
  
  		end = start + frag_iter->len;
  		if ((copy = end - offset) > 0) {
  			if (copy > len)
  				copy = len;
  			sum = atalk_sum_skb(frag_iter, offset - start,
  					    copy, sum);
  			if ((len -= copy) == 0)
  				return sum;
  			offset += copy;
  		}
  		start = end;
  	}
  
  	BUG_ON(len > 0);
  
  	return sum;
  }
  
  static __be16 atalk_checksum(const struct sk_buff *skb, int len)
  {
  	unsigned long sum;
  
  	/* skip header 4 bytes */
  	sum = atalk_sum_skb(skb, 4, len-4, 0);
  
  	/* Use 0xFFFF for 0. 0 itself means none */
  	return sum ? htons((unsigned short)sum) : htons(0xFFFF);
  }
  
  static struct proto ddp_proto = {
  	.name	  = "DDP",
  	.owner	  = THIS_MODULE,
  	.obj_size = sizeof(struct atalk_sock),
  };
  
  /*
   * Create a socket. Initialise the socket, blank the addresses
   * set the state.
   */
  static int atalk_create(struct net *net, struct socket *sock, int protocol,
  			int kern)
  {
  	struct sock *sk;
  	int rc = -ESOCKTNOSUPPORT;
  
  	if (!net_eq(net, &init_net))
  		return -EAFNOSUPPORT;
  
  	/*
  	 * We permit SOCK_DGRAM and RAW is an extension. It is trivial to do
  	 * and gives you the full ELAP frame. Should be handy for CAP 8)
  	 */
  	if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
  		goto out;
  	rc = -ENOMEM;
  	sk = sk_alloc(net, PF_APPLETALK, GFP_KERNEL, &ddp_proto, kern);
  	if (!sk)
  		goto out;
  	rc = 0;
  	sock->ops = &atalk_dgram_ops;
  	sock_init_data(sock, sk);
  
  	/* Checksums on by default */
  	sock_set_flag(sk, SOCK_ZAPPED);
  out:
  	return rc;
  }
  
  /* Free a socket. No work needed */
  static int atalk_release(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  
  	if (sk) {
  		sock_hold(sk);
  		lock_sock(sk);
  
  		sock_orphan(sk);
  		sock->sk = NULL;
  		atalk_destroy_socket(sk);
  
  		release_sock(sk);
  		sock_put(sk);
  	}
  	return 0;
  }
  
  /**
   * atalk_pick_and_bind_port - Pick a source port when one is not given
   * @sk: socket to insert into the tables
   * @sat: address to search for
   *
   * Pick a source port when one is not given. If we can find a suitable free
   * one, we insert the socket into the tables using it.
   *
   * This whole operation must be atomic.
   */
  static int atalk_pick_and_bind_port(struct sock *sk, struct sockaddr_at *sat)
  {
  	int retval;
  
  	write_lock_bh(&atalk_sockets_lock);
  
  	for (sat->sat_port = ATPORT_RESERVED;
  	     sat->sat_port < ATPORT_LAST;
  	     sat->sat_port++) {
  		struct sock *s;
  
  		sk_for_each(s, &atalk_sockets) {
  			struct atalk_sock *at = at_sk(s);
  
  			if (at->src_net == sat->sat_addr.s_net &&
  			    at->src_node == sat->sat_addr.s_node &&
  			    at->src_port == sat->sat_port)
  				goto try_next_port;
  		}
  
  		/* Wheee, it's free, assign and insert. */
  		__atalk_insert_socket(sk);
  		at_sk(sk)->src_port = sat->sat_port;
  		retval = 0;
  		goto out;
  
  try_next_port:;
  	}
  
  	retval = -EBUSY;
  out:
  	write_unlock_bh(&atalk_sockets_lock);
  	return retval;
  }
  
  static int atalk_autobind(struct sock *sk)
  {
  	struct atalk_sock *at = at_sk(sk);
  	struct sockaddr_at sat;
  	struct atalk_addr *ap = atalk_find_primary();
  	int n = -EADDRNOTAVAIL;
  
  	if (!ap || ap->s_net == htons(ATADDR_ANYNET))
  		goto out;
  
  	at->src_net  = sat.sat_addr.s_net  = ap->s_net;
  	at->src_node = sat.sat_addr.s_node = ap->s_node;
  
  	n = atalk_pick_and_bind_port(sk, &sat);
  	if (!n)
  		sock_reset_flag(sk, SOCK_ZAPPED);
  out:
  	return n;
  }
  
  /* Set the address 'our end' of the connection */
  static int atalk_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
  {
  	struct sockaddr_at *addr = (struct sockaddr_at *)uaddr;
  	struct sock *sk = sock->sk;
  	struct atalk_sock *at = at_sk(sk);
  	int err;
  
  	if (!sock_flag(sk, SOCK_ZAPPED) ||
  	    addr_len != sizeof(struct sockaddr_at))
  		return -EINVAL;
  
  	if (addr->sat_family != AF_APPLETALK)
  		return -EAFNOSUPPORT;
  
  	lock_sock(sk);
  	if (addr->sat_addr.s_net == htons(ATADDR_ANYNET)) {
  		struct atalk_addr *ap = atalk_find_primary();
  
  		err = -EADDRNOTAVAIL;
  		if (!ap)
  			goto out;
  
  		at->src_net  = addr->sat_addr.s_net = ap->s_net;
  		at->src_node = addr->sat_addr.s_node = ap->s_node;
  	} else {
  		err = -EADDRNOTAVAIL;
  		if (!atalk_find_interface(addr->sat_addr.s_net,
  					  addr->sat_addr.s_node))
  			goto out;
  
  		at->src_net  = addr->sat_addr.s_net;
  		at->src_node = addr->sat_addr.s_node;
  	}
  
  	if (addr->sat_port == ATADDR_ANYPORT) {
  		err = atalk_pick_and_bind_port(sk, addr);
  
  		if (err < 0)
  			goto out;
  	} else {
  		at->src_port = addr->sat_port;
  
  		err = -EADDRINUSE;
  		if (atalk_find_or_insert_socket(sk, addr))
  			goto out;
  	}
  
  	sock_reset_flag(sk, SOCK_ZAPPED);
  	err = 0;
  out:
  	release_sock(sk);
  	return err;
  }
  
  /* Set the address we talk to */
  static int atalk_connect(struct socket *sock, struct sockaddr *uaddr,
  			 int addr_len, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct atalk_sock *at = at_sk(sk);
  	struct sockaddr_at *addr;
  	int err;
  
  	sk->sk_state   = TCP_CLOSE;
  	sock->state = SS_UNCONNECTED;
  
  	if (addr_len != sizeof(*addr))
  		return -EINVAL;
  
  	addr = (struct sockaddr_at *)uaddr;
  
  	if (addr->sat_family != AF_APPLETALK)
  		return -EAFNOSUPPORT;
  
  	if (addr->sat_addr.s_node == ATADDR_BCAST &&
  	    !sock_flag(sk, SOCK_BROADCAST)) {
  #if 1
  		pr_warn("atalk_connect: %s is broken and did not set SO_BROADCAST.\n",
  			current->comm);
  #else
  		return -EACCES;
  #endif
  	}
  
  	lock_sock(sk);
  	err = -EBUSY;
  	if (sock_flag(sk, SOCK_ZAPPED))
  		if (atalk_autobind(sk) < 0)
  			goto out;
  
  	err = -ENETUNREACH;
  	if (!atrtr_get_dev(&addr->sat_addr))
  		goto out;
  
  	at->dest_port = addr->sat_port;
  	at->dest_net  = addr->sat_addr.s_net;
  	at->dest_node = addr->sat_addr.s_node;
  
  	sock->state  = SS_CONNECTED;
  	sk->sk_state = TCP_ESTABLISHED;
  	err = 0;
  out:
  	release_sock(sk);
  	return err;
  }
  
  /*
   * Find the name of an AppleTalk socket. Just copy the right
   * fields into the sockaddr.
   */
  static int atalk_getname(struct socket *sock, struct sockaddr *uaddr,
  			 int *uaddr_len, int peer)
  {
  	struct sockaddr_at sat;
  	struct sock *sk = sock->sk;
  	struct atalk_sock *at = at_sk(sk);
  	int err;
  
  	lock_sock(sk);
  	err = -ENOBUFS;
  	if (sock_flag(sk, SOCK_ZAPPED))
  		if (atalk_autobind(sk) < 0)
  			goto out;
  
  	*uaddr_len = sizeof(struct sockaddr_at);
  	memset(&sat, 0, sizeof(sat));
  
  	if (peer) {
  		err = -ENOTCONN;
  		if (sk->sk_state != TCP_ESTABLISHED)
  			goto out;
  
  		sat.sat_addr.s_net  = at->dest_net;
  		sat.sat_addr.s_node = at->dest_node;
  		sat.sat_port	    = at->dest_port;
  	} else {
  		sat.sat_addr.s_net  = at->src_net;
  		sat.sat_addr.s_node = at->src_node;
  		sat.sat_port	    = at->src_port;
  	}
  
  	err = 0;
  	sat.sat_family = AF_APPLETALK;
  	memcpy(uaddr, &sat, sizeof(sat));
  
  out:
  	release_sock(sk);
  	return err;
  }
  
  #if IS_ENABLED(CONFIG_IPDDP)
  static __inline__ int is_ip_over_ddp(struct sk_buff *skb)
  {
  	return skb->data[12] == 22;
  }
  
  static int handle_ip_over_ddp(struct sk_buff *skb)
  {
  	struct net_device *dev = __dev_get_by_name(&init_net, "ipddp0");
  	struct net_device_stats *stats;
  
  	/* This needs to be able to handle ipddp"N" devices */
  	if (!dev) {
  		kfree_skb(skb);
  		return NET_RX_DROP;
  	}
  
  	skb->protocol = htons(ETH_P_IP);
  	skb_pull(skb, 13);
  	skb->dev   = dev;
  	skb_reset_transport_header(skb);
  
  	stats = netdev_priv(dev);
  	stats->rx_packets++;
  	stats->rx_bytes += skb->len + 13;
  	return netif_rx(skb);  /* Send the SKB up to a higher place. */
  }
  #else
  /* make it easy for gcc to optimize this test out, i.e. kill the code */
  #define is_ip_over_ddp(skb) 0
  #define handle_ip_over_ddp(skb) 0
  #endif
  
  static int atalk_route_packet(struct sk_buff *skb, struct net_device *dev,
  			      struct ddpehdr *ddp, __u16 len_hops, int origlen)
  {
  	struct atalk_route *rt;
  	struct atalk_addr ta;
  
  	/*
  	 * Don't route multicast, etc., packets, or packets sent to "this
  	 * network"
  	 */
  	if (skb->pkt_type != PACKET_HOST || !ddp->deh_dnet) {
  		/*
  		 * FIXME:
  		 *
  		 * Can it ever happen that a packet is from a PPP iface and
  		 * needs to be broadcast onto the default network?
  		 */
  		if (dev->type == ARPHRD_PPP)
  			printk(KERN_DEBUG "AppleTalk: didn't forward broadcast "
  					  "packet received from PPP iface\n");
  		goto free_it;
  	}
  
  	ta.s_net  = ddp->deh_dnet;
  	ta.s_node = ddp->deh_dnode;
  
  	/* Route the packet */
  	rt = atrtr_find(&ta);
  	/* increment hops count */
  	len_hops += 1 << 10;
  	if (!rt || !(len_hops & (15 << 10)))
  		goto free_it;
  
  	/* FIXME: use skb->cb to be able to use shared skbs */
  
  	/*
  	 * Route goes through another gateway, so set the target to the
  	 * gateway instead.
  	 */
  
  	if (rt->flags & RTF_GATEWAY) {
  		ta.s_net  = rt->gateway.s_net;
  		ta.s_node = rt->gateway.s_node;
  	}
  
  	/* Fix up skb->len field */
  	skb_trim(skb, min_t(unsigned int, origlen,
  			    (rt->dev->hard_header_len +
  			     ddp_dl->header_length + (len_hops & 1023))));
  
  	/* FIXME: use skb->cb to be able to use shared skbs */
  	ddp->deh_len_hops = htons(len_hops);
  
  	/*
  	 * Send the buffer onwards
  	 *
  	 * Now we must always be careful. If it's come from LocalTalk to
  	 * EtherTalk it might not fit
  	 *
  	 * Order matters here: If a packet has to be copied to make a new
  	 * headroom (rare hopefully) then it won't need unsharing.
  	 *
  	 * Note. ddp-> becomes invalid at the realloc.
  	 */
  	if (skb_headroom(skb) < 22) {
  		/* 22 bytes - 12 ether, 2 len, 3 802.2 5 snap */
  		struct sk_buff *nskb = skb_realloc_headroom(skb, 32);
  		kfree_skb(skb);
  		skb = nskb;
  	} else
  		skb = skb_unshare(skb, GFP_ATOMIC);
  
  	/*
  	 * If the buffer didn't vanish into the lack of space bitbucket we can
  	 * send it.
  	 */
  	if (skb == NULL)
  		goto drop;
  
  	if (aarp_send_ddp(rt->dev, skb, &ta, NULL) == NET_XMIT_DROP)
  		return NET_RX_DROP;
  	return NET_RX_SUCCESS;
  free_it:
  	kfree_skb(skb);
  drop:
  	return NET_RX_DROP;
  }
  
  /**
   *	atalk_rcv - Receive a packet (in skb) from device dev
   *	@skb - packet received
   *	@dev - network device where the packet comes from
   *	@pt - packet type
   *
   *	Receive a packet (in skb) from device dev. This has come from the SNAP
   *	decoder, and on entry skb->transport_header is the DDP header, skb->len
   *	is the DDP header, skb->len is the DDP length. The physical headers
   *	have been extracted. PPP should probably pass frames marked as for this
   *	layer.  [ie ARPHRD_ETHERTALK]
   */
  static int atalk_rcv(struct sk_buff *skb, struct net_device *dev,
  		     struct packet_type *pt, struct net_device *orig_dev)
  {
  	struct ddpehdr *ddp;
  	struct sock *sock;
  	struct atalk_iface *atif;
  	struct sockaddr_at tosat;
  	int origlen;
  	__u16 len_hops;
  
  	if (!net_eq(dev_net(dev), &init_net))
  		goto drop;
  
  	/* Don't mangle buffer if shared */
  	if (!(skb = skb_share_check(skb, GFP_ATOMIC)))
  		goto out;
  
  	/* Size check and make sure header is contiguous */
  	if (!pskb_may_pull(skb, sizeof(*ddp)))
  		goto drop;
  
  	ddp = ddp_hdr(skb);
  
  	len_hops = ntohs(ddp->deh_len_hops);
  
  	/* Trim buffer in case of stray trailing data */
  	origlen = skb->len;
  	skb_trim(skb, min_t(unsigned int, skb->len, len_hops & 1023));
  
  	/*
  	 * Size check to see if ddp->deh_len was crap
  	 * (Otherwise we'll detonate most spectacularly
  	 * in the middle of atalk_checksum() or recvmsg()).
  	 */
  	if (skb->len < sizeof(*ddp) || skb->len < (len_hops & 1023)) {
  		pr_debug("AppleTalk: dropping corrupted frame (deh_len=%u, "
  			 "skb->len=%u)\n", len_hops & 1023, skb->len);
  		goto drop;
  	}
  
  	/*
  	 * Any checksums. Note we don't do htons() on this == is assumed to be
  	 * valid for net byte orders all over the networking code...
  	 */
  	if (ddp->deh_sum &&
  	    atalk_checksum(skb, len_hops & 1023) != ddp->deh_sum)
  		/* Not a valid AppleTalk frame - dustbin time */
  		goto drop;
  
  	/* Check the packet is aimed at us */
  	if (!ddp->deh_dnet)	/* Net 0 is 'this network' */
  		atif = atalk_find_anynet(ddp->deh_dnode, dev);
  	else
  		atif = atalk_find_interface(ddp->deh_dnet, ddp->deh_dnode);
  
  	if (!atif) {
  		/* Not ours, so we route the packet via the correct
  		 * AppleTalk iface
  		 */
  		return atalk_route_packet(skb, dev, ddp, len_hops, origlen);
  	}
  
  	/* if IP over DDP is not selected this code will be optimized out */
  	if (is_ip_over_ddp(skb))
  		return handle_ip_over_ddp(skb);
  	/*
  	 * Which socket - atalk_search_socket() looks for a *full match*
  	 * of the <net, node, port> tuple.
  	 */
  	tosat.sat_addr.s_net  = ddp->deh_dnet;
  	tosat.sat_addr.s_node = ddp->deh_dnode;
  	tosat.sat_port	      = ddp->deh_dport;
  
  	sock = atalk_search_socket(&tosat, atif);
  	if (!sock) /* But not one of our sockets */
  		goto drop;
  
  	/* Queue packet (standard) */
  	if (sock_queue_rcv_skb(sock, skb) < 0)
  		goto drop;
  
  	return NET_RX_SUCCESS;
  
  drop:
  	kfree_skb(skb);
  out:
  	return NET_RX_DROP;
  
  }
  
  /*
   * Receive a LocalTalk frame. We make some demands on the caller here.
   * Caller must provide enough headroom on the packet to pull the short
   * header and append a long one.
   */
  static int ltalk_rcv(struct sk_buff *skb, struct net_device *dev,
  		     struct packet_type *pt, struct net_device *orig_dev)
  {
  	if (!net_eq(dev_net(dev), &init_net))
  		goto freeit;
  
  	/* Expand any short form frames */
  	if (skb_mac_header(skb)[2] == 1) {
  		struct ddpehdr *ddp;
  		/* Find our address */
  		struct atalk_addr *ap = atalk_find_dev_addr(dev);
  
  		if (!ap || skb->len < sizeof(__be16) || skb->len > 1023)
  			goto freeit;
  
  		/* Don't mangle buffer if shared */
  		if (!(skb = skb_share_check(skb, GFP_ATOMIC)))
  			return 0;
  
  		/*
  		 * The push leaves us with a ddephdr not an shdr, and
  		 * handily the port bytes in the right place preset.
  		 */
  		ddp = skb_push(skb, sizeof(*ddp) - 4);
  
  		/* Now fill in the long header */
  
  		/*
  		 * These two first. The mac overlays the new source/dest
  		 * network information so we MUST copy these before
  		 * we write the network numbers !
  		 */
  
  		ddp->deh_dnode = skb_mac_header(skb)[0];     /* From physical header */
  		ddp->deh_snode = skb_mac_header(skb)[1];     /* From physical header */
  
  		ddp->deh_dnet  = ap->s_net;	/* Network number */
  		ddp->deh_snet  = ap->s_net;
  		ddp->deh_sum   = 0;		/* No checksum */
  		/*
  		 * Not sure about this bit...
  		 */
  		/* Non routable, so force a drop if we slip up later */
  		ddp->deh_len_hops = htons(skb->len + (DDP_MAXHOPS << 10));
  	}
  	skb_reset_transport_header(skb);
  
  	return atalk_rcv(skb, dev, pt, orig_dev);
  freeit:
  	kfree_skb(skb);
  	return 0;
  }
  
  static int atalk_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
  {
  	struct sock *sk = sock->sk;
  	struct atalk_sock *at = at_sk(sk);
  	DECLARE_SOCKADDR(struct sockaddr_at *, usat, msg->msg_name);
  	int flags = msg->msg_flags;
  	int loopback = 0;
  	struct sockaddr_at local_satalk, gsat;
  	struct sk_buff *skb;
  	struct net_device *dev;
  	struct ddpehdr *ddp;
  	int size;
  	struct atalk_route *rt;
  	int err;
  
  	if (flags & ~(MSG_DONTWAIT|MSG_CMSG_COMPAT))
  		return -EINVAL;
  
  	if (len > DDP_MAXSZ)
  		return -EMSGSIZE;
  
  	lock_sock(sk);
  	if (usat) {
  		err = -EBUSY;
  		if (sock_flag(sk, SOCK_ZAPPED))
  			if (atalk_autobind(sk) < 0)
  				goto out;
  
  		err = -EINVAL;
  		if (msg->msg_namelen < sizeof(*usat) ||
  		    usat->sat_family != AF_APPLETALK)
  			goto out;
  
  		err = -EPERM;
  		/* netatalk didn't implement this check */
  		if (usat->sat_addr.s_node == ATADDR_BCAST &&
  		    !sock_flag(sk, SOCK_BROADCAST)) {
  			goto out;
  		}
  	} else {
  		err = -ENOTCONN;
  		if (sk->sk_state != TCP_ESTABLISHED)
  			goto out;
  		usat = &local_satalk;
  		usat->sat_family      = AF_APPLETALK;
  		usat->sat_port	      = at->dest_port;
  		usat->sat_addr.s_node = at->dest_node;
  		usat->sat_addr.s_net  = at->dest_net;
  	}
  
  	/* Build a packet */
  	SOCK_DEBUG(sk, "SK %p: Got address.\n", sk);
  
  	/* For headers */
  	size = sizeof(struct ddpehdr) + len + ddp_dl->header_length;
  
  	if (usat->sat_addr.s_net || usat->sat_addr.s_node == ATADDR_ANYNODE) {
  		rt = atrtr_find(&usat->sat_addr);
  	} else {
  		struct atalk_addr at_hint;
  
  		at_hint.s_node = 0;
  		at_hint.s_net  = at->src_net;
  
  		rt = atrtr_find(&at_hint);
  	}
  	err = -ENETUNREACH;
  	if (!rt)
  		goto out;
  
  	dev = rt->dev;
  
  	SOCK_DEBUG(sk, "SK %p: Size needed %d, device %s\n",
  			sk, size, dev->name);
  
  	size += dev->hard_header_len;
  	release_sock(sk);
  	skb = sock_alloc_send_skb(sk, size, (flags & MSG_DONTWAIT), &err);
  	lock_sock(sk);
  	if (!skb)
  		goto out;
  
  	skb_reserve(skb, ddp_dl->header_length);
  	skb_reserve(skb, dev->hard_header_len);
  	skb->dev = dev;
  
  	SOCK_DEBUG(sk, "SK %p: Begin build.\n", sk);
  
  	ddp = skb_put(skb, sizeof(struct ddpehdr));
  	ddp->deh_len_hops  = htons(len + sizeof(*ddp));
  	ddp->deh_dnet  = usat->sat_addr.s_net;
  	ddp->deh_snet  = at->src_net;
  	ddp->deh_dnode = usat->sat_addr.s_node;
  	ddp->deh_snode = at->src_node;
  	ddp->deh_dport = usat->sat_port;
  	ddp->deh_sport = at->src_port;
  
  	SOCK_DEBUG(sk, "SK %p: Copy user data (%zd bytes).\n", sk, len);
  
  	err = memcpy_from_msg(skb_put(skb, len), msg, len);
  	if (err) {
  		kfree_skb(skb);
  		err = -EFAULT;
  		goto out;
  	}
  
  	if (sk->sk_no_check_tx)
  		ddp->deh_sum = 0;
  	else
  		ddp->deh_sum = atalk_checksum(skb, len + sizeof(*ddp));
  
  	/*
  	 * Loopback broadcast packets to non gateway targets (ie routes
  	 * to group we are in)
  	 */
  	if (ddp->deh_dnode == ATADDR_BCAST &&
  	    !(rt->flags & RTF_GATEWAY) && !(dev->flags & IFF_LOOPBACK)) {
  		struct sk_buff *skb2 = skb_copy(skb, GFP_KERNEL);
  
  		if (skb2) {
  			loopback = 1;
  			SOCK_DEBUG(sk, "SK %p: send out(copy).\n", sk);
  			/*
  			 * If it fails it is queued/sent above in the aarp queue
  			 */
  			aarp_send_ddp(dev, skb2, &usat->sat_addr, NULL);
  		}
  	}
  
  	if (dev->flags & IFF_LOOPBACK || loopback) {
  		SOCK_DEBUG(sk, "SK %p: Loop back.\n", sk);
  		/* loop back */
  		skb_orphan(skb);
  		if (ddp->deh_dnode == ATADDR_BCAST) {
  			struct atalk_addr at_lo;
  
  			at_lo.s_node = 0;
  			at_lo.s_net  = 0;
  
  			rt = atrtr_find(&at_lo);
  			if (!rt) {
  				kfree_skb(skb);
  				err = -ENETUNREACH;
  				goto out;
  			}
  			dev = rt->dev;
  			skb->dev = dev;
  		}
  		ddp_dl->request(ddp_dl, skb, dev->dev_addr);
  	} else {
  		SOCK_DEBUG(sk, "SK %p: send out.\n", sk);
  		if (rt->flags & RTF_GATEWAY) {
  		    gsat.sat_addr = rt->gateway;
  		    usat = &gsat;
  		}
  
  		/*
  		 * If it fails it is queued/sent above in the aarp queue
  		 */
  		aarp_send_ddp(dev, skb, &usat->sat_addr, NULL);
  	}
  	SOCK_DEBUG(sk, "SK %p: Done write (%zd).\n", sk, len);
  
  out:
  	release_sock(sk);
  	return err ? : len;
  }
  
  static int atalk_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
  			 int flags)
  {
  	struct sock *sk = sock->sk;
  	struct ddpehdr *ddp;
  	int copied = 0;
  	int offset = 0;
  	int err = 0;
  	struct sk_buff *skb;
  
  	skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
  						flags & MSG_DONTWAIT, &err);
  	lock_sock(sk);
  
  	if (!skb)
  		goto out;
  
  	/* FIXME: use skb->cb to be able to use shared skbs */
  	ddp = ddp_hdr(skb);
  	copied = ntohs(ddp->deh_len_hops) & 1023;
  
  	if (sk->sk_type != SOCK_RAW) {
  		offset = sizeof(*ddp);
  		copied -= offset;
  	}
  
  	if (copied > size) {
  		copied = size;
  		msg->msg_flags |= MSG_TRUNC;
  	}
  	err = skb_copy_datagram_msg(skb, offset, msg, copied);
  
  	if (!err && msg->msg_name) {
  		DECLARE_SOCKADDR(struct sockaddr_at *, sat, msg->msg_name);
  		sat->sat_family      = AF_APPLETALK;
  		sat->sat_port        = ddp->deh_sport;
  		sat->sat_addr.s_node = ddp->deh_snode;
  		sat->sat_addr.s_net  = ddp->deh_snet;
  		msg->msg_namelen     = sizeof(*sat);
  	}
  
  	skb_free_datagram(sk, skb);	/* Free the datagram. */
  
  out:
  	release_sock(sk);
  	return err ? : copied;
  }
  
  
  /*
   * AppleTalk ioctl calls.
   */
  static int atalk_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
  {
  	int rc = -ENOIOCTLCMD;
  	struct sock *sk = sock->sk;
  	void __user *argp = (void __user *)arg;
  
  	switch (cmd) {
  	/* Protocol layer */
  	case TIOCOUTQ: {
  		long amount = sk->sk_sndbuf - sk_wmem_alloc_get(sk);
  
  		if (amount < 0)
  			amount = 0;
  		rc = put_user(amount, (int __user *)argp);
  		break;
  	}
  	case TIOCINQ: {
  		/*
  		 * These two are safe on a single CPU system as only
  		 * user tasks fiddle here
  		 */
  		struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
  		long amount = 0;
  
  		if (skb)
  			amount = skb->len - sizeof(struct ddpehdr);
  		rc = put_user(amount, (int __user *)argp);
  		break;
  	}
  	case SIOCGSTAMP:
  		rc = sock_get_timestamp(sk, argp);
  		break;
  	case SIOCGSTAMPNS:
  		rc = sock_get_timestampns(sk, argp);
  		break;
  	/* Routing */
  	case SIOCADDRT:
  	case SIOCDELRT:
  		rc = -EPERM;
  		if (capable(CAP_NET_ADMIN))
  			rc = atrtr_ioctl(cmd, argp);
  		break;
  	/* Interface */
  	case SIOCGIFADDR:
  	case SIOCSIFADDR:
  	case SIOCGIFBRDADDR:
  	case SIOCATALKDIFADDR:
  	case SIOCDIFADDR:
  	case SIOCSARP:		/* proxy AARP */
  	case SIOCDARP:		/* proxy AARP */
  		rtnl_lock();
  		rc = atif_ioctl(cmd, argp);
  		rtnl_unlock();
  		break;
  	}
  
  	return rc;
  }
  
  
  #ifdef CONFIG_COMPAT
  static int atalk_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
  {
  	/*
  	 * SIOCATALKDIFADDR is a SIOCPROTOPRIVATE ioctl number, so we
  	 * cannot handle it in common code. The data we access if ifreq
  	 * here is compatible, so we can simply call the native
  	 * handler.
  	 */
  	if (cmd == SIOCATALKDIFADDR)
  		return atalk_ioctl(sock, cmd, (unsigned long)compat_ptr(arg));
  
  	return -ENOIOCTLCMD;
  }
  #endif
  
  
  static const struct net_proto_family atalk_family_ops = {
  	.family		= PF_APPLETALK,
  	.create		= atalk_create,
  	.owner		= THIS_MODULE,
  };
  
  static const struct proto_ops atalk_dgram_ops = {
  	.family		= PF_APPLETALK,
  	.owner		= THIS_MODULE,
  	.release	= atalk_release,
  	.bind		= atalk_bind,
  	.connect	= atalk_connect,
  	.socketpair	= sock_no_socketpair,
  	.accept		= sock_no_accept,
  	.getname	= atalk_getname,
  	.poll		= datagram_poll,
  	.ioctl		= atalk_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= atalk_compat_ioctl,
  #endif
  	.listen		= sock_no_listen,
  	.shutdown	= sock_no_shutdown,
  	.setsockopt	= sock_no_setsockopt,
  	.getsockopt	= sock_no_getsockopt,
  	.sendmsg	= atalk_sendmsg,
  	.recvmsg	= atalk_recvmsg,
  	.mmap		= sock_no_mmap,
  	.sendpage	= sock_no_sendpage,
  };
  
  static struct notifier_block ddp_notifier = {
  	.notifier_call	= ddp_device_event,
  };
  
  static struct packet_type ltalk_packet_type __read_mostly = {
  	.type		= cpu_to_be16(ETH_P_LOCALTALK),
  	.func		= ltalk_rcv,
  };
  
  static struct packet_type ppptalk_packet_type __read_mostly = {
  	.type		= cpu_to_be16(ETH_P_PPPTALK),
  	.func		= atalk_rcv,
  };
  
  static unsigned char ddp_snap_id[] = { 0x08, 0x00, 0x07, 0x80, 0x9B };
  
  /* Export symbols for use by drivers when AppleTalk is a module */
  EXPORT_SYMBOL(atrtr_get_dev);
  EXPORT_SYMBOL(atalk_find_dev_addr);
  
  static const char atalk_err_snap[] __initconst =
  	KERN_CRIT "Unable to register DDP with SNAP.\n";
  
  /* Called by proto.c on kernel start up */
  static int __init atalk_init(void)
  {
  	int rc;
  
  	rc = proto_register(&ddp_proto, 0);
  	if (rc)
  		goto out;
  
  	rc = sock_register(&atalk_family_ops);
  	if (rc)
  		goto out_proto;
  
  	ddp_dl = register_snap_client(ddp_snap_id, atalk_rcv);
  	if (!ddp_dl)
  		printk(atalk_err_snap);
  
  	dev_add_pack(&ltalk_packet_type);
  	dev_add_pack(&ppptalk_packet_type);
  
  	rc = register_netdevice_notifier(&ddp_notifier);
  	if (rc)
  		goto out_sock;
  
  	aarp_proto_init();
  	rc = atalk_proc_init();
  	if (rc)
  		goto out_aarp;
  
  	rc = atalk_register_sysctl();
  	if (rc)
  		goto out_proc;
  out:
  	return rc;
  out_proc:
  	atalk_proc_exit();
  out_aarp:
  	aarp_cleanup_module();
  	unregister_netdevice_notifier(&ddp_notifier);
  out_sock:
  	dev_remove_pack(&ppptalk_packet_type);
  	dev_remove_pack(&ltalk_packet_type);
  	unregister_snap_client(ddp_dl);
  	sock_unregister(PF_APPLETALK);
  out_proto:
  	proto_unregister(&ddp_proto);
  	goto out;
  }
  module_init(atalk_init);
  
  /*
   * No explicit module reference count manipulation is needed in the
   * protocol. Socket layer sets module reference count for us
   * and interfaces reference counting is done
   * by the network device layer.
   *
   * Ergo, before the AppleTalk module can be removed, all AppleTalk
   * sockets be closed from user space.
   */
  static void __exit atalk_exit(void)
  {
  #ifdef CONFIG_SYSCTL
  	atalk_unregister_sysctl();
  #endif /* CONFIG_SYSCTL */
  	atalk_proc_exit();
  	aarp_cleanup_module();	/* General aarp clean-up. */
  	unregister_netdevice_notifier(&ddp_notifier);
  	dev_remove_pack(&ltalk_packet_type);
  	dev_remove_pack(&ppptalk_packet_type);
  	unregister_snap_client(ddp_dl);
  	sock_unregister(PF_APPLETALK);
  	proto_unregister(&ddp_proto);
  }
  module_exit(atalk_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
  MODULE_DESCRIPTION("AppleTalk 0.20\n");
  MODULE_ALIAS_NETPROTO(PF_APPLETALK);
  