/*
 * 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.
 *
 * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
 * Copyright Tomi Manninen OH2BNS (oh2bns@sral.fi)
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <net/arp.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/termios.h>      /* For TIOCINQ/OUTQ */
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <net/netrom.h>
#include <linux/seq_file.h>
#include <linux/export.h>

static unsigned int nr_neigh_no = 1;

static HLIST_HEAD(nr_node_list);
static DEFINE_SPINLOCK(nr_node_list_lock);
static HLIST_HEAD(nr_neigh_list);
static DEFINE_SPINLOCK(nr_neigh_list_lock);

static struct nr_node *nr_node_get(ax25_address *callsign)
{
        struct nr_node *found = NULL;
        struct nr_node *nr_node;

        spin_lock_bh(&nr_node_list_lock);
        nr_node_for_each(nr_node, &nr_node_list)
                if (ax25cmp(callsign, &nr_node->callsign) == 0) {
                        nr_node_hold(nr_node);
                        found = nr_node;
                        break;
                }
        spin_unlock_bh(&nr_node_list_lock);
        return found;
}

static struct nr_neigh *nr_neigh_get_dev(ax25_address *callsign,
                                         struct net_device *dev)
{
        struct nr_neigh *found = NULL;
        struct nr_neigh *nr_neigh;

        spin_lock_bh(&nr_neigh_list_lock);
        nr_neigh_for_each(nr_neigh, &nr_neigh_list)
                if (ax25cmp(callsign, &nr_neigh->callsign) == 0 &&
                    nr_neigh->dev == dev) {
                        nr_neigh_hold(nr_neigh);
                        found = nr_neigh;
                        break;
                }
        spin_unlock_bh(&nr_neigh_list_lock);
        return found;
}

static void nr_remove_neigh(struct nr_neigh *);

/*
 *      Add a new route to a node, and in the process add the node and the
 *      neighbour if it is new.
 */
static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic,
        ax25_address *ax25, ax25_digi *ax25_digi, struct net_device *dev,
        int quality, int obs_count)
{
        struct nr_node  *nr_node;
        struct nr_neigh *nr_neigh;
        struct nr_route nr_route;
        int i, found;
        struct net_device *odev;

        if ((odev=nr_dev_get(nr)) != NULL) {    /* Can't add routes to ourself */
                dev_put(odev);
                return -EINVAL;
        }

        nr_node = nr_node_get(nr);

        nr_neigh = nr_neigh_get_dev(ax25, dev);

        /*
         * The L2 link to a neighbour has failed in the past
         * and now a frame comes from this neighbour. We assume
         * it was a temporary trouble with the link and reset the
         * routes now (and not wait for a node broadcast).
         */
        if (nr_neigh != NULL && nr_neigh->failed != 0 && quality == 0) {
                struct nr_node *nr_nodet;

                spin_lock_bh(&nr_node_list_lock);
                nr_node_for_each(nr_nodet, &nr_node_list) {
                        nr_node_lock(nr_nodet);
                        for (i = 0; i < nr_nodet->count; i++)
                                if (nr_nodet->routes[i].neighbour == nr_neigh)
                                        if (i < nr_nodet->which)
                                                nr_nodet->which = i;
                        nr_node_unlock(nr_nodet);
                }
                spin_unlock_bh(&nr_node_list_lock);
        }

        if (nr_neigh != NULL)
                nr_neigh->failed = 0;

        if (quality == 0 && nr_neigh != NULL && nr_node != NULL) {
                nr_neigh_put(nr_neigh);
                nr_node_put(nr_node);
                return 0;
        }

        if (nr_neigh == NULL) {
                if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL) {
                        if (nr_node)
                                nr_node_put(nr_node);
                        return -ENOMEM;
                }

                nr_neigh->callsign = *ax25;
                nr_neigh->digipeat = NULL;
                nr_neigh->ax25     = NULL;
                nr_neigh->dev      = dev;
                nr_neigh->quality  = sysctl_netrom_default_path_quality;
                nr_neigh->locked   = 0;
                nr_neigh->count    = 0;
                nr_neigh->number   = nr_neigh_no++;
                nr_neigh->failed   = 0;
                atomic_set(&nr_neigh->refcount, 1);

                if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
                        nr_neigh->digipeat = kmemdup(ax25_digi,
                                                     sizeof(*ax25_digi),
                                                     GFP_KERNEL);
                        if (nr_neigh->digipeat == NULL) {
                                kfree(nr_neigh);
                                if (nr_node)
                                        nr_node_put(nr_node);
                                return -ENOMEM;
                        }
                }

                spin_lock_bh(&nr_neigh_list_lock);
                hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
                nr_neigh_hold(nr_neigh);
                spin_unlock_bh(&nr_neigh_list_lock);
        }

        if (quality != 0 && ax25cmp(nr, ax25) == 0 && !nr_neigh->locked)
                nr_neigh->quality = quality;

        if (nr_node == NULL) {
                if ((nr_node = kmalloc(sizeof(*nr_node), GFP_ATOMIC)) == NULL) {
                        if (nr_neigh)
                                nr_neigh_put(nr_neigh);
                        return -ENOMEM;
                }

                nr_node->callsign = *nr;
                strcpy(nr_node->mnemonic, mnemonic);

                nr_node->which = 0;
                nr_node->count = 1;
                atomic_set(&nr_node->refcount, 1);
                spin_lock_init(&nr_node->node_lock);

                nr_node->routes[0].quality   = quality;
                nr_node->routes[0].obs_count = obs_count;
                nr_node->routes[0].neighbour = nr_neigh;

                nr_neigh_hold(nr_neigh);
                nr_neigh->count++;

                spin_lock_bh(&nr_node_list_lock);
                hlist_add_head(&nr_node->node_node, &nr_node_list);
                /* refcount initialized at 1 */
                spin_unlock_bh(&nr_node_list_lock);

                return 0;
        }
        nr_node_lock(nr_node);

        if (quality != 0)
                strcpy(nr_node->mnemonic, mnemonic);

        for (found = 0, i = 0; i < nr_node->count; i++) {
                if (nr_node->routes[i].neighbour == nr_neigh) {
                        nr_node->routes[i].quality   = quality;
                        nr_node->routes[i].obs_count = obs_count;
                        found = 1;
                        break;
                }
        }

        if (!found) {
                /* We have space at the bottom, slot it in */
                if (nr_node->count < 3) {
                        nr_node->routes[2] = nr_node->routes[1];
                        nr_node->routes[1] = nr_node->routes[0];

                        nr_node->routes[0].quality   = quality;
                        nr_node->routes[0].obs_count = obs_count;
                        nr_node->routes[0].neighbour = nr_neigh;

                        nr_node->which++;
                        nr_node->count++;
                        nr_neigh_hold(nr_neigh);
                        nr_neigh->count++;
                } else {
                        /* It must be better than the worst */
                        if (quality > nr_node->routes[2].quality) {
                                nr_node->routes[2].neighbour->count--;
                                nr_neigh_put(nr_node->routes[2].neighbour);

                                if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked)
                                        nr_remove_neigh(nr_node->routes[2].neighbour);

                                nr_node->routes[2].quality   = quality;
                                nr_node->routes[2].obs_count = obs_count;
                                nr_node->routes[2].neighbour = nr_neigh;

                                nr_neigh_hold(nr_neigh);
                                nr_neigh->count++;
                        }
                }
        }

        /* Now re-sort the routes in quality order */
        switch (nr_node->count) {
        case 3:
                if (nr_node->routes[1].quality > nr_node->routes[0].quality) {
                        switch (nr_node->which) {
                        case 0:
                                nr_node->which = 1;
                                break;
                        case 1:
                                nr_node->which = 0;
                                break;
                        }
                        nr_route           = nr_node->routes[0];
                        nr_node->routes[0] = nr_node->routes[1];
                        nr_node->routes[1] = nr_route;
                }
                if (nr_node->routes[2].quality > nr_node->routes[1].quality) {
                        switch (nr_node->which) {
                        case 1:  nr_node->which = 2;
                                break;

                        case 2:  nr_node->which = 1;
                                break;

                        default:
                                break;
                        }
                        nr_route           = nr_node->routes[1];
                        nr_node->routes[1] = nr_node->routes[2];
                        nr_node->routes[2] = nr_route;
                }
        case 2:
                if (nr_node->routes[1].quality > nr_node->routes[0].quality) {
                        switch (nr_node->which) {
                        case 0:  nr_node->which = 1;
                                break;

                        case 1:  nr_node->which = 0;
                                break;

                        default: break;
                        }
                        nr_route           = nr_node->routes[0];
                        nr_node->routes[0] = nr_node->routes[1];
                        nr_node->routes[1] = nr_route;
                        }
        case 1:
                break;
        }

        for (i = 0; i < nr_node->count; i++) {
                if (nr_node->routes[i].neighbour == nr_neigh) {
                        if (i < nr_node->which)
                                nr_node->which = i;
                        break;
                }
        }

        nr_neigh_put(nr_neigh);
        nr_node_unlock(nr_node);
        nr_node_put(nr_node);
        return 0;
}

static inline void __nr_remove_node(struct nr_node *nr_node)
{
        hlist_del_init(&nr_node->node_node);
        nr_node_put(nr_node);
}

#define nr_remove_node_locked(__node) \
        __nr_remove_node(__node)

static void nr_remove_node(struct nr_node *nr_node)
{
        spin_lock_bh(&nr_node_list_lock);
        __nr_remove_node(nr_node);
        spin_unlock_bh(&nr_node_list_lock);
}

static inline void __nr_remove_neigh(struct nr_neigh *nr_neigh)
{
        hlist_del_init(&nr_neigh->neigh_node);
        nr_neigh_put(nr_neigh);
}

#define nr_remove_neigh_locked(__neigh) \
        __nr_remove_neigh(__neigh)

static void nr_remove_neigh(struct nr_neigh *nr_neigh)
{
        spin_lock_bh(&nr_neigh_list_lock);
        __nr_remove_neigh(nr_neigh);
        spin_unlock_bh(&nr_neigh_list_lock);
}

/*
 *      "Delete" a node. Strictly speaking remove a route to a node. The node
 *      is only deleted if no routes are left to it.
 */
static int nr_del_node(ax25_address *callsign, ax25_address *neighbour, struct net_device *dev)
{
        struct nr_node  *nr_node;
        struct nr_neigh *nr_neigh;
        int i;

        nr_node = nr_node_get(callsign);

        if (nr_node == NULL)
                return -EINVAL;

        nr_neigh = nr_neigh_get_dev(neighbour, dev);

        if (nr_neigh == NULL) {
                nr_node_put(nr_node);
                return -EINVAL;
        }

        nr_node_lock(nr_node);
        for (i = 0; i < nr_node->count; i++) {
                if (nr_node->routes[i].neighbour == nr_neigh) {
                        nr_neigh->count--;
                        nr_neigh_put(nr_neigh);

                        if (nr_neigh->count == 0 && !nr_neigh->locked)
                                nr_remove_neigh(nr_neigh);
                        nr_neigh_put(nr_neigh);

                        nr_node->count--;

                        if (nr_node->count == 0) {
                                nr_remove_node(nr_node);
                        } else {
                                switch (i) {
                                case 0:
                                        nr_node->routes[0] = nr_node->routes[1];
                                case 1:
                                        nr_node->routes[1] = nr_node->routes[2];
                                case 2:
                                        break;
                                }
                                nr_node_put(nr_node);
                        }
                        nr_node_unlock(nr_node);

                        return 0;
                }
        }
        nr_neigh_put(nr_neigh);
        nr_node_unlock(nr_node);
        nr_node_put(nr_node);

        return -EINVAL;
}

/*
 *      Lock a neighbour with a quality.
 */
static int __must_check nr_add_neigh(ax25_address *callsign,
        ax25_digi *ax25_digi, struct net_device *dev, unsigned int quality)
{
        struct nr_neigh *nr_neigh;

        nr_neigh = nr_neigh_get_dev(callsign, dev);
        if (nr_neigh) {
                nr_neigh->quality = quality;
                nr_neigh->locked  = 1;
                nr_neigh_put(nr_neigh);
                return 0;
        }

        if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL)
                return -ENOMEM;

        nr_neigh->callsign = *callsign;
        nr_neigh->digipeat = NULL;
        nr_neigh->ax25     = NULL;
        nr_neigh->dev      = dev;
        nr_neigh->quality  = quality;
        nr_neigh->locked   = 1;
        nr_neigh->count    = 0;
        nr_neigh->number   = nr_neigh_no++;
        nr_neigh->failed   = 0;
        atomic_set(&nr_neigh->refcount, 1);

        if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
                nr_neigh->digipeat = kmemdup(ax25_digi, sizeof(*ax25_digi),
                                             GFP_KERNEL);
                if (nr_neigh->digipeat == NULL) {
                        kfree(nr_neigh);
                        return -ENOMEM;
                }
        }

        spin_lock_bh(&nr_neigh_list_lock);
        hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
        /* refcount is initialized at 1 */
        spin_unlock_bh(&nr_neigh_list_lock);

        return 0;
}

/*
 *      "Delete" a neighbour. The neighbour is only removed if the number
 *      of nodes that may use it is zero.
 */
static int nr_del_neigh(ax25_address *callsign, struct net_device *dev, unsigned int quality)
{
        struct nr_neigh *nr_neigh;

        nr_neigh = nr_neigh_get_dev(callsign, dev);

        if (nr_neigh == NULL) return -EINVAL;

        nr_neigh->quality = quality;
        nr_neigh->locked  = 0;

        if (nr_neigh->count == 0)
                nr_remove_neigh(nr_neigh);
        nr_neigh_put(nr_neigh);

        return 0;
}

/*
 *      Decrement the obsolescence count by one. If a route is reduced to a
 *      count of zero, remove it. Also remove any unlocked neighbours with
 *      zero nodes routing via it.
 */
static int nr_dec_obs(void)
{
        struct nr_neigh *nr_neigh;
        struct nr_node  *s;
        struct hlist_node *nodet;
        int i;

        spin_lock_bh(&nr_node_list_lock);
        nr_node_for_each_safe(s, nodet, &nr_node_list) {
                nr_node_lock(s);
                for (i = 0; i < s->count; i++) {
                        switch (s->routes[i].obs_count) {
                        case 0:         /* A locked entry */
                                break;

                        case 1:         /* From 1 -> 0 */
                                nr_neigh = s->routes[i].neighbour;

                                nr_neigh->count--;
                                nr_neigh_put(nr_neigh);

                                if (nr_neigh->count == 0 && !nr_neigh->locked)
                                        nr_remove_neigh(nr_neigh);

                                s->count--;

                                switch (i) {
                                case 0:
                                        s->routes[0] = s->routes[1];
                                        /* Fallthrough */
                                case 1:
                                        s->routes[1] = s->routes[2];
                                case 2:
                                        break;
                                }
                                break;

                        default:
                                s->routes[i].obs_count--;
                                break;

                        }
                }

                if (s->count <= 0)
                        nr_remove_node_locked(s);
                nr_node_unlock(s);
        }
        spin_unlock_bh(&nr_node_list_lock);

        return 0;
}

/*
 *      A device has been removed. Remove its routes and neighbours.
 */
void nr_rt_device_down(struct net_device *dev)
{
        struct nr_neigh *s;
        struct hlist_node *nodet, *node2t;
        struct nr_node  *t;
        int i;

        spin_lock_bh(&nr_neigh_list_lock);
        nr_neigh_for_each_safe(s, nodet, &nr_neigh_list) {
                if (s->dev == dev) {
                        spin_lock_bh(&nr_node_list_lock);
                        nr_node_for_each_safe(t, node2t, &nr_node_list) {
                                nr_node_lock(t);
                                for (i = 0; i < t->count; i++) {
                                        if (t->routes[i].neighbour == s) {
                                                t->count--;

                                                switch (i) {
                                                case 0:
                                                        t->routes[0] = t->routes[1];
                                                case 1:
                                                        t->routes[1] = t->routes[2];
                                                case 2:
                                                        break;
                                                }
                                        }
                                }

                                if (t->count <= 0)
                                        nr_remove_node_locked(t);
                                nr_node_unlock(t);
                        }
                        spin_unlock_bh(&nr_node_list_lock);

                        nr_remove_neigh_locked(s);
                }
        }
        spin_unlock_bh(&nr_neigh_list_lock);
}

/*
 *      Check that the device given is a valid AX.25 interface that is "up".
 *      Or a valid ethernet interface with an AX.25 callsign binding.
 */
static struct net_device *nr_ax25_dev_get(char *devname)
{
        struct net_device *dev;

        if ((dev = dev_get_by_name(&init_net, devname)) == NULL)
                return NULL;

        if ((dev->flags & IFF_UP) && dev->type == ARPHRD_AX25)
                return dev;

        dev_put(dev);
        return NULL;
}

/*
 *      Find the first active NET/ROM device, usually "nr0".
 */
struct net_device *nr_dev_first(void)
{
        struct net_device *dev, *first = NULL;

        rcu_read_lock();
        for_each_netdev_rcu(&init_net, dev) {
                if ((dev->flags & IFF_UP) && dev->type == ARPHRD_NETROM)
                        if (first == NULL || strncmp(dev->name, first->name, 3) < 0)
                                first = dev;
        }
        if (first)
                dev_hold(first);
        rcu_read_unlock();

        return first;
}

/*
 *      Find the NET/ROM device for the given callsign.
 */
struct net_device *nr_dev_get(ax25_address *addr)
{
        struct net_device *dev;

        rcu_read_lock();
        for_each_netdev_rcu(&init_net, dev) {
                if ((dev->flags & IFF_UP) && dev->type == ARPHRD_NETROM &&
                    ax25cmp(addr, (ax25_address *)dev->dev_addr) == 0) {
                        dev_hold(dev);
                        goto out;
                }
        }
        dev = NULL;
out:
        rcu_read_unlock();
        return dev;
}

static ax25_digi *nr_call_to_digi(ax25_digi *digi, int ndigis,
        ax25_address *digipeaters)
{
        int i;

        if (ndigis == 0)
                return NULL;

        for (i = 0; i < ndigis; i++) {
                digi->calls[i]    = digipeaters[i];
                digi->repeated[i] = 0;
        }

        digi->ndigi      = ndigis;
        digi->lastrepeat = -1;

        return digi;
}

/*
 *      Handle the ioctls that control the routing functions.
 */
int nr_rt_ioctl(unsigned int cmd, void __user *arg)
{
        struct nr_route_struct nr_route;
        struct net_device *dev;
        ax25_digi digi;
        int ret;

        switch (cmd) {
        case SIOCADDRT:
                if (copy_from_user(&nr_route, arg, sizeof(struct nr_route_struct)))
                        return -EFAULT;
                if (nr_route.ndigis > AX25_MAX_DIGIS)
                        return -EINVAL;
                if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
                        return -EINVAL;
                switch (nr_route.type) {
                case NETROM_NODE:
                        if (strnlen(nr_route.mnemonic, 7) == 7) {
                                ret = -EINVAL;
                                break;
                        }

                        ret = nr_add_node(&nr_route.callsign,
                                nr_route.mnemonic,
                                &nr_route.neighbour,
                                nr_call_to_digi(&digi, nr_route.ndigis,
                                                nr_route.digipeaters),
                                dev, nr_route.quality,
                                nr_route.obs_count);
                        break;
                case NETROM_NEIGH:
                        ret = nr_add_neigh(&nr_route.callsign,
                                nr_call_to_digi(&digi, nr_route.ndigis,
                                                nr_route.digipeaters),
                                dev, nr_route.quality);
                        break;
                default:
                        ret = -EINVAL;
                }
                dev_put(dev);
                return ret;

        case SIOCDELRT:
                if (copy_from_user(&nr_route, arg, sizeof(struct nr_route_struct)))
                        return -EFAULT;
                if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
                        return -EINVAL;
                switch (nr_route.type) {
                case NETROM_NODE:
                        ret = nr_del_node(&nr_route.callsign,
                                &nr_route.neighbour, dev);
                        break;
                case NETROM_NEIGH:
                        ret = nr_del_neigh(&nr_route.callsign,
                                dev, nr_route.quality);
                        break;
                default:
                        ret = -EINVAL;
                }
                dev_put(dev);
                return ret;

        case SIOCNRDECOBS:
                return nr_dec_obs();

        default:
                return -EINVAL;
        }

        return 0;
}

/*
 *      A level 2 link has timed out, therefore it appears to be a poor link,
 *      then don't use that neighbour until it is reset.
 */
void nr_link_failed(ax25_cb *ax25, int reason)
{
        struct nr_neigh *s, *nr_neigh = NULL;
        struct nr_node  *nr_node = NULL;

        spin_lock_bh(&nr_neigh_list_lock);
        nr_neigh_for_each(s, &nr_neigh_list) {
                if (s->ax25 == ax25) {
                        nr_neigh_hold(s);
                        nr_neigh = s;
                        break;
                }
        }
        spin_unlock_bh(&nr_neigh_list_lock);

        if (nr_neigh == NULL)
                return;

        nr_neigh->ax25 = NULL;
        ax25_cb_put(ax25);

        if (++nr_neigh->failed < sysctl_netrom_link_fails_count) {
                nr_neigh_put(nr_neigh);
                return;
        }
        spin_lock_bh(&nr_node_list_lock);
        nr_node_for_each(nr_node, &nr_node_list) {
                nr_node_lock(nr_node);
                if (nr_node->which < nr_node->count &&
                    nr_node->routes[nr_node->which].neighbour == nr_neigh)
                        nr_node->which++;
                nr_node_unlock(nr_node);
        }
        spin_unlock_bh(&nr_node_list_lock);
        nr_neigh_put(nr_neigh);
}

/*
 *      Route a frame to an appropriate AX.25 connection. A NULL ax25_cb
 *      indicates an internally generated frame.
 */
int nr_route_frame(struct sk_buff *skb, ax25_cb *ax25)
{
        ax25_address *nr_src, *nr_dest;
        struct nr_neigh *nr_neigh;
        struct nr_node  *nr_node;
        struct net_device *dev;
        unsigned char *dptr;
        ax25_cb *ax25s;
        int ret;
        struct sk_buff *skbn;


        nr_src  = (ax25_address *)(skb->data + 0);
        nr_dest = (ax25_address *)(skb->data + 7);

        if (ax25 != NULL) {
                ret = nr_add_node(nr_src, "", &ax25->dest_addr, ax25->digipeat,
                                  ax25->ax25_dev->dev, 0,
                                  sysctl_netrom_obsolescence_count_initialiser);
                if (ret)
                        return ret;
        }

        if ((dev = nr_dev_get(nr_dest)) != NULL) {      /* Its for me */
                if (ax25 == NULL)                       /* Its from me */
                        ret = nr_loopback_queue(skb);
                else
                        ret = nr_rx_frame(skb, dev);
                dev_put(dev);
                return ret;
        }

        if (!sysctl_netrom_routing_control && ax25 != NULL)
                return 0;

        /* Its Time-To-Live has expired */
        if (skb->data[14] == 1) {
                return 0;
        }

        nr_node = nr_node_get(nr_dest);
        if (nr_node == NULL)
                return 0;
        nr_node_lock(nr_node);

        if (nr_node->which >= nr_node->count) {
                nr_node_unlock(nr_node);
                nr_node_put(nr_node);
                return 0;
        }

        nr_neigh = nr_node->routes[nr_node->which].neighbour;

        if ((dev = nr_dev_first()) == NULL) {
                nr_node_unlock(nr_node);
                nr_node_put(nr_node);
                return 0;
        }

        /* We are going to change the netrom headers so we should get our
           own skb, we also did not know until now how much header space
           we had to reserve... - RXQ */
        if ((skbn=skb_copy_expand(skb, dev->hard_header_len, 0, GFP_ATOMIC)) == NULL) {
                nr_node_unlock(nr_node);
                nr_node_put(nr_node);
                dev_put(dev);
                return 0;
        }
        kfree_skb(skb);
        skb=skbn;
        skb->data[14]--;

        dptr  = skb_push(skb, 1);
        *dptr = AX25_P_NETROM;

        ax25s = nr_neigh->ax25;
        nr_neigh->ax25 = ax25_send_frame(skb, 256,
                                         (ax25_address *)dev->dev_addr,
                                         &nr_neigh->callsign,
                                         nr_neigh->digipeat, nr_neigh->dev);
        if (ax25s)
                ax25_cb_put(ax25s);

        dev_put(dev);
        ret = (nr_neigh->ax25 != NULL);
        nr_node_unlock(nr_node);
        nr_node_put(nr_node);

        return ret;
}

#ifdef CONFIG_PROC_FS

static void *nr_node_start(struct seq_file *seq, loff_t *pos)
{
        spin_lock_bh(&nr_node_list_lock);
        return seq_hlist_start_head(&nr_node_list, *pos);
}

static void *nr_node_next(struct seq_file *seq, void *v, loff_t *pos)
{
        return seq_hlist_next(v, &nr_node_list, pos);
}

static void nr_node_stop(struct seq_file *seq, void *v)
{
        spin_unlock_bh(&nr_node_list_lock);
}

static int nr_node_show(struct seq_file *seq, void *v)
{
        char buf[11];
        int i;

        if (v == SEQ_START_TOKEN)
                seq_puts(seq,
                         "callsign  mnemonic w n qual obs neigh qual obs neigh qual obs neigh\n");
        else {
                struct nr_node *nr_node = hlist_entry(v, struct nr_node,
                                                      node_node);

                nr_node_lock(nr_node);
                seq_printf(seq, "%-9s %-7s  %d %d",
                        ax2asc(buf, &nr_node->callsign),
                        (nr_node->mnemonic[0] == '\0') ? "*" : nr_node->mnemonic,
                        nr_node->which + 1,
                        nr_node->count);

                for (i = 0; i < nr_node->count; i++) {
                        seq_printf(seq, "  %3d   %d %05d",
                                nr_node->routes[i].quality,
                                nr_node->routes[i].obs_count,
                                nr_node->routes[i].neighbour->number);
                }
                nr_node_unlock(nr_node);

                seq_puts(seq, "\n");
        }
        return 0;
}

static const struct seq_operations nr_node_seqops = {
        .start = nr_node_start,
        .next = nr_node_next,
        .stop = nr_node_stop,
        .show = nr_node_show,
};

static int nr_node_info_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &nr_node_seqops);
}

const struct file_operations nr_nodes_fops = {
        .owner = THIS_MODULE,
        .open = nr_node_info_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release,
};

static void *nr_neigh_start(struct seq_file *seq, loff_t *pos)
{
        spin_lock_bh(&nr_neigh_list_lock);
        return seq_hlist_start_head(&nr_neigh_list, *pos);
}

static void *nr_neigh_next(struct seq_file *seq, void *v, loff_t *pos)
{
        return seq_hlist_next(v, &nr_neigh_list, pos);
}

static void nr_neigh_stop(struct seq_file *seq, void *v)
{
        spin_unlock_bh(&nr_neigh_list_lock);
}

static int nr_neigh_show(struct seq_file *seq, void *v)
{
        char buf[11];
        int i;

        if (v == SEQ_START_TOKEN)
                seq_puts(seq, "addr  callsign  dev  qual lock count failed digipeaters\n");
        else {
                struct nr_neigh *nr_neigh;

                nr_neigh = hlist_entry(v, struct nr_neigh, neigh_node);
                seq_printf(seq, "%05d %-9s %-4s  %3d    %d   %3d    %3d",
                        nr_neigh->number,
                        ax2asc(buf, &nr_neigh->callsign),
                        nr_neigh->dev ? nr_neigh->dev->name : "???",
                        nr_neigh->quality,
                        nr_neigh->locked,
                        nr_neigh->count,
                        nr_neigh->failed);

                if (nr_neigh->digipeat != NULL) {
                        for (i = 0; i < nr_neigh->digipeat->ndigi; i++)
                                seq_printf(seq, " %s",
                                           ax2asc(buf, &nr_neigh->digipeat->calls[i]));
                }

                seq_puts(seq, "\n");
        }
        return 0;
}

static const struct seq_operations nr_neigh_seqops = {
        .start = nr_neigh_start,
        .next = nr_neigh_next,
        .stop = nr_neigh_stop,
        .show = nr_neigh_show,
};

static int nr_neigh_info_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &nr_neigh_seqops);
}

const struct file_operations nr_neigh_fops = {
        .owner = THIS_MODULE,
        .open = nr_neigh_info_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release,
};

#endif

/*
 *      Free all memory associated with the nodes and routes lists.
 */
void __exit nr_rt_free(void)
{
        struct nr_neigh *s = NULL;
        struct nr_node  *t = NULL;
        struct hlist_node *nodet;

        spin_lock_bh(&nr_neigh_list_lock);
        spin_lock_bh(&nr_node_list_lock);
        nr_node_for_each_safe(t, nodet, &nr_node_list) {
                nr_node_lock(t);
                nr_remove_node_locked(t);
                nr_node_unlock(t);
        }
        nr_neigh_for_each_safe(s, nodet, &nr_neigh_list) {
                while(s->count) {
                        s->count--;
                        nr_neigh_put(s);
                }
                nr_remove_neigh_locked(s);
        }
        spin_unlock_bh(&nr_node_list_lock);
        spin_unlock_bh(&nr_neigh_list_lock);
}