// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright (C) Terry Dawson VK2KTJ (terry@animats.net)
 */
#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 <net/tcp_states.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 <net/rose.h>
#include <linux/seq_file.h>
#include <linux/export.h>

static unsigned int rose_neigh_no = 1;

static struct rose_node  *rose_node_list;
static DEFINE_SPINLOCK(rose_node_list_lock);
static struct rose_neigh *rose_neigh_list;
static DEFINE_SPINLOCK(rose_neigh_list_lock);
static struct rose_route *rose_route_list;
static DEFINE_SPINLOCK(rose_route_list_lock);

struct rose_neigh *rose_loopback_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 rose_add_node(struct rose_route_struct *rose_route,
        struct net_device *dev)
{
        struct rose_node  *rose_node, *rose_tmpn, *rose_tmpp;
        struct rose_neigh *rose_neigh;
        int i, res = 0;

        spin_lock_bh(&rose_node_list_lock);
        spin_lock_bh(&rose_neigh_list_lock);

        rose_node = rose_node_list;
        while (rose_node != NULL) {
                if ((rose_node->mask == rose_route->mask) &&
                    (rosecmpm(&rose_route->address, &rose_node->address,
                              rose_route->mask) == 0))
                        break;
                rose_node = rose_node->next;
        }

        if (rose_node != NULL && rose_node->loopback) {
                res = -EINVAL;
                goto out;
        }

        rose_neigh = rose_neigh_list;
        while (rose_neigh != NULL) {
                if (ax25cmp(&rose_route->neighbour,
                            &rose_neigh->callsign) == 0 &&
                    rose_neigh->dev == dev)
                        break;
                rose_neigh = rose_neigh->next;
        }

        if (rose_neigh == NULL) {
                rose_neigh = kmalloc_obj(*rose_neigh, GFP_ATOMIC);
                if (rose_neigh == NULL) {
                        res = -ENOMEM;
                        goto out;
                }

                rose_neigh->callsign  = rose_route->neighbour;
                rose_neigh->digipeat  = NULL;
                rose_neigh->ax25      = NULL;
                rose_neigh->dev       = dev;
                rose_neigh->count     = 0;
                rose_neigh->dce_mode  = 0;
                rose_neigh->loopback  = 0;
                rose_neigh->number    = rose_neigh_no++;
                rose_neigh->restarted = 0;
                refcount_set(&rose_neigh->use, 1);

                skb_queue_head_init(&rose_neigh->queue);

                timer_setup(&rose_neigh->ftimer, NULL, 0);
                timer_setup(&rose_neigh->t0timer, NULL, 0);

                if (rose_route->ndigis != 0) {
                        rose_neigh->digipeat =
                                kmalloc_obj(ax25_digi, GFP_ATOMIC);
                        if (rose_neigh->digipeat == NULL) {
                                kfree(rose_neigh);
                                res = -ENOMEM;
                                goto out;
                        }

                        rose_neigh->digipeat->ndigi      = rose_route->ndigis;
                        rose_neigh->digipeat->lastrepeat = -1;

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

                rose_neigh->next = rose_neigh_list;
                rose_neigh_list  = rose_neigh;
        }

        /*
         * This is a new node to be inserted into the list. Find where it needs
         * to be inserted into the list, and insert it. We want to be sure
         * to order the list in descending order of mask size to ensure that
         * later when we are searching this list the first match will be the
         * best match.
         */
        if (rose_node == NULL) {
                rose_tmpn = rose_node_list;
                rose_tmpp = NULL;

                while (rose_tmpn != NULL) {
                        if (rose_tmpn->mask > rose_route->mask) {
                                rose_tmpp = rose_tmpn;
                                rose_tmpn = rose_tmpn->next;
                        } else {
                                break;
                        }
                }

                /* create new node */
                rose_node = kmalloc_obj(*rose_node, GFP_ATOMIC);
                if (rose_node == NULL) {
                        res = -ENOMEM;
                        goto out;
                }

                rose_node->address      = rose_route->address;
                rose_node->mask         = rose_route->mask;
                rose_node->count        = 1;
                rose_node->loopback     = 0;
                rose_node->neighbour[0] = rose_neigh;

                if (rose_tmpn == NULL) {
                        if (rose_tmpp == NULL) {        /* Empty list */
                                rose_node_list  = rose_node;
                                rose_node->next = NULL;
                        } else {
                                rose_tmpp->next = rose_node;
                                rose_node->next = NULL;
                        }
                } else {
                        if (rose_tmpp == NULL) {        /* 1st node */
                                rose_node->next = rose_node_list;
                                rose_node_list  = rose_node;
                        } else {
                                rose_tmpp->next = rose_node;
                                rose_node->next = rose_tmpn;
                        }
                }
                rose_neigh->count++;
                rose_neigh_hold(rose_neigh);

                goto out;
        }

        /* We have space, slot it in */
        if (rose_node->count < 3) {
                rose_node->neighbour[rose_node->count] = rose_neigh;
                rose_node->count++;
                rose_neigh->count++;
                rose_neigh_hold(rose_neigh);
        }

out:
        spin_unlock_bh(&rose_neigh_list_lock);
        spin_unlock_bh(&rose_node_list_lock);

        return res;
}

/*
 * Caller is holding rose_node_list_lock.
 */
static void rose_remove_node(struct rose_node *rose_node)
{
        struct rose_node *s;

        if ((s = rose_node_list) == rose_node) {
                rose_node_list = rose_node->next;
                kfree(rose_node);
                return;
        }

        while (s != NULL && s->next != NULL) {
                if (s->next == rose_node) {
                        s->next = rose_node->next;
                        kfree(rose_node);
                        return;
                }

                s = s->next;
        }
}

/*
 * Caller is holding rose_neigh_list_lock.
 */
static void rose_remove_neigh(struct rose_neigh *rose_neigh)
{
        struct rose_neigh *s;

        timer_delete_sync(&rose_neigh->ftimer);
        timer_delete_sync(&rose_neigh->t0timer);

        skb_queue_purge(&rose_neigh->queue);

        if ((s = rose_neigh_list) == rose_neigh) {
                rose_neigh_list = rose_neigh->next;
                return;
        }

        while (s != NULL && s->next != NULL) {
                if (s->next == rose_neigh) {
                        s->next = rose_neigh->next;
                        return;
                }

                s = s->next;
        }
}

/*
 * Caller is holding rose_route_list_lock.
 */
static void rose_remove_route(struct rose_route *rose_route)
{
        struct rose_route *s;

        if (rose_route->neigh1 != NULL)
                rose_neigh_put(rose_route->neigh1);

        if (rose_route->neigh2 != NULL)
                rose_neigh_put(rose_route->neigh2);

        if ((s = rose_route_list) == rose_route) {
                rose_route_list = rose_route->next;
                kfree(rose_route);
                return;
        }

        while (s != NULL && s->next != NULL) {
                if (s->next == rose_route) {
                        s->next = rose_route->next;
                        kfree(rose_route);
                        return;
                }

                s = s->next;
        }
}

/*
 *      "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 rose_del_node(struct rose_route_struct *rose_route,
        struct net_device *dev)
{
        struct rose_node  *rose_node;
        struct rose_neigh *rose_neigh;
        int i, err = 0;

        spin_lock_bh(&rose_node_list_lock);
        spin_lock_bh(&rose_neigh_list_lock);

        rose_node = rose_node_list;
        while (rose_node != NULL) {
                if ((rose_node->mask == rose_route->mask) &&
                    (rosecmpm(&rose_route->address, &rose_node->address,
                              rose_route->mask) == 0))
                        break;
                rose_node = rose_node->next;
        }

        if (rose_node == NULL || rose_node->loopback) {
                err = -EINVAL;
                goto out;
        }

        rose_neigh = rose_neigh_list;
        while (rose_neigh != NULL) {
                if (ax25cmp(&rose_route->neighbour,
                            &rose_neigh->callsign) == 0 &&
                    rose_neigh->dev == dev)
                        break;
                rose_neigh = rose_neigh->next;
        }

        if (rose_neigh == NULL) {
                err = -EINVAL;
                goto out;
        }

        for (i = 0; i < rose_node->count; i++) {
                if (rose_node->neighbour[i] == rose_neigh) {
                        rose_neigh->count--;
                        rose_neigh_put(rose_neigh);

                        if (rose_neigh->count == 0) {
                                rose_remove_neigh(rose_neigh);
                                rose_neigh_put(rose_neigh);
                        }

                        rose_node->count--;

                        if (rose_node->count == 0) {
                                rose_remove_node(rose_node);
                        } else {
                                switch (i) {
                                case 0:
                                        rose_node->neighbour[0] =
                                                rose_node->neighbour[1];
                                        fallthrough;
                                case 1:
                                        rose_node->neighbour[1] =
                                                rose_node->neighbour[2];
                                        break;
                                case 2:
                                        break;
                                }
                        }
                        goto out;
                }
        }
        err = -EINVAL;

out:
        spin_unlock_bh(&rose_neigh_list_lock);
        spin_unlock_bh(&rose_node_list_lock);

        return err;
}

/*
 *      Add the loopback neighbour.
 */
void rose_add_loopback_neigh(void)
{
        struct rose_neigh *sn;

        rose_loopback_neigh = kmalloc_obj(struct rose_neigh);
        if (!rose_loopback_neigh)
                return;
        sn = rose_loopback_neigh;

        sn->callsign  = null_ax25_address;
        sn->digipeat  = NULL;
        sn->ax25      = NULL;
        sn->dev       = NULL;
        sn->count     = 0;
        sn->dce_mode  = 1;
        sn->loopback  = 1;
        sn->number    = rose_neigh_no++;
        sn->restarted = 1;
        refcount_set(&sn->use, 1);

        skb_queue_head_init(&sn->queue);

        timer_setup(&sn->ftimer, NULL, 0);
        timer_setup(&sn->t0timer, NULL, 0);

        spin_lock_bh(&rose_neigh_list_lock);
        sn->next = rose_neigh_list;
        rose_neigh_list           = sn;
        spin_unlock_bh(&rose_neigh_list_lock);
}

/*
 *      Add a loopback node.
 */
int rose_add_loopback_node(const rose_address *address)
{
        struct rose_node *rose_node;
        int err = 0;

        spin_lock_bh(&rose_node_list_lock);

        rose_node = rose_node_list;
        while (rose_node != NULL) {
                if ((rose_node->mask == 10) &&
                     (rosecmpm(address, &rose_node->address, 10) == 0) &&
                     rose_node->loopback)
                        break;
                rose_node = rose_node->next;
        }

        if (rose_node != NULL)
                goto out;

        if ((rose_node = kmalloc_obj(*rose_node, GFP_ATOMIC)) == NULL) {
                err = -ENOMEM;
                goto out;
        }

        rose_node->address      = *address;
        rose_node->mask         = 10;
        rose_node->count        = 1;
        rose_node->loopback     = 1;
        rose_node->neighbour[0] = rose_loopback_neigh;

        /* Insert at the head of list. Address is always mask=10 */
        rose_node->next = rose_node_list;
        rose_node_list  = rose_node;

        rose_loopback_neigh->count++;
        rose_neigh_hold(rose_loopback_neigh);

out:
        spin_unlock_bh(&rose_node_list_lock);

        return err;
}

/*
 *      Delete a loopback node.
 */
void rose_del_loopback_node(const rose_address *address)
{
        struct rose_node *rose_node;

        spin_lock_bh(&rose_node_list_lock);

        rose_node = rose_node_list;
        while (rose_node != NULL) {
                if ((rose_node->mask == 10) &&
                    (rosecmpm(address, &rose_node->address, 10) == 0) &&
                    rose_node->loopback)
                        break;
                rose_node = rose_node->next;
        }

        if (rose_node == NULL)
                goto out;

        rose_remove_node(rose_node);

        rose_loopback_neigh->count--;
        rose_neigh_put(rose_loopback_neigh);

out:
        spin_unlock_bh(&rose_node_list_lock);
}

/*
 *      A device has been removed. Remove its routes and neighbours.
 */
void rose_rt_device_down(struct net_device *dev)
{
        struct rose_neigh *s, *rose_neigh;
        struct rose_node  *t, *rose_node;
        int i;

        spin_lock_bh(&rose_node_list_lock);
        spin_lock_bh(&rose_neigh_list_lock);
        rose_neigh = rose_neigh_list;
        while (rose_neigh != NULL) {
                s          = rose_neigh;
                rose_neigh = rose_neigh->next;

                if (s->dev != dev)
                        continue;

                rose_node = rose_node_list;

                while (rose_node != NULL) {
                        t         = rose_node;
                        rose_node = rose_node->next;

                        for (i = t->count - 1; i >= 0; i--) {
                                if (t->neighbour[i] != s)
                                        continue;

                                t->count--;

                                memmove(&t->neighbour[i], &t->neighbour[i + 1],
                                        sizeof(t->neighbour[0]) *
                                                (t->count - i));
                                rose_neigh_put(s);
                        }

                        if (t->count <= 0)
                                rose_remove_node(t);
                }

                rose_remove_neigh(s);
                rose_neigh_put(s);
        }
        spin_unlock_bh(&rose_neigh_list_lock);
        spin_unlock_bh(&rose_node_list_lock);
}

#if 0 /* Currently unused */
/*
 *      A device has been removed. Remove its links.
 */
void rose_route_device_down(struct net_device *dev)
{
        struct rose_route *s, *rose_route;

        spin_lock_bh(&rose_route_list_lock);
        rose_route = rose_route_list;
        while (rose_route != NULL) {
                s          = rose_route;
                rose_route = rose_route->next;

                if (s->neigh1->dev == dev || s->neigh2->dev == dev)
                        rose_remove_route(s);
        }
        spin_unlock_bh(&rose_route_list_lock);
}
#endif

/*
 *      Clear all nodes and neighbours out, except for neighbours with
 *      active connections going through them.
 *  Do not clear loopback neighbour and nodes.
 */
static int rose_clear_routes(void)
{
        struct rose_neigh *s, *rose_neigh;
        struct rose_node  *t, *rose_node;
        int i;

        spin_lock_bh(&rose_node_list_lock);
        spin_lock_bh(&rose_neigh_list_lock);

        rose_neigh = rose_neigh_list;
        rose_node  = rose_node_list;

        while (rose_node != NULL) {
                t         = rose_node;
                rose_node = rose_node->next;

                if (!t->loopback) {
                        for (i = 0; i < t->count; i++)
                                rose_neigh_put(t->neighbour[i]);
                        rose_remove_node(t);
                }
        }

        while (rose_neigh != NULL) {
                s          = rose_neigh;
                rose_neigh = rose_neigh->next;

                if (!s->loopback) {
                        rose_remove_neigh(s);
                        rose_neigh_put(s);
                }
        }

        spin_unlock_bh(&rose_neigh_list_lock);
        spin_unlock_bh(&rose_node_list_lock);

        return 0;
}

/*
 *      Check that the device given is a valid AX.25 interface that is "up".
 *      called with RTNL
 */
static struct net_device *rose_ax25_dev_find(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;

        return NULL;
}

/*
 *      Find the first active ROSE device, usually "rose0".
 */
struct net_device *rose_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_ROSE)
                        if (first == NULL || strncmp(dev->name, first->name, 3) < 0)
                                first = dev;
        }
        if (first)
                dev_hold(first);
        rcu_read_unlock();

        return first;
}

/*
 *      Find the ROSE device for the given address.
 */
struct net_device *rose_dev_get(rose_address *addr)
{
        struct net_device *dev;

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

static int rose_dev_exists(rose_address *addr)
{
        struct net_device *dev;

        rcu_read_lock();
        for_each_netdev_rcu(&init_net, dev) {
                if ((dev->flags & IFF_UP) && dev->type == ARPHRD_ROSE &&
                    rosecmp(addr, (const rose_address *)dev->dev_addr) == 0)
                        goto out;
        }
        dev = NULL;
out:
        rcu_read_unlock();
        return dev != NULL;
}




struct rose_route *rose_route_free_lci(unsigned int lci, struct rose_neigh *neigh)
{
        struct rose_route *rose_route;

        for (rose_route = rose_route_list; rose_route != NULL; rose_route = rose_route->next)
                if ((rose_route->neigh1 == neigh && rose_route->lci1 == lci) ||
                    (rose_route->neigh2 == neigh && rose_route->lci2 == lci))
                        return rose_route;

        return NULL;
}

/*
 *      Find a neighbour or a route given a ROSE address.
 */
struct rose_neigh *rose_get_neigh(rose_address *addr, unsigned char *cause,
        unsigned char *diagnostic, int route_frame)
{
        struct rose_neigh *res = NULL;
        struct rose_node *node;
        int failed = 0;
        int i;

        if (!route_frame) spin_lock_bh(&rose_node_list_lock);
        for (node = rose_node_list; node != NULL; node = node->next) {
                if (rosecmpm(addr, &node->address, node->mask) == 0) {
                        for (i = 0; i < node->count; i++) {
                                if (node->neighbour[i]->restarted) {
                                        res = node->neighbour[i];
                                        rose_neigh_hold(node->neighbour[i]);
                                        goto out;
                                }
                        }
                }
        }
        if (!route_frame) { /* connect request */
                for (node = rose_node_list; node != NULL; node = node->next) {
                        if (rosecmpm(addr, &node->address, node->mask) == 0) {
                                for (i = 0; i < node->count; i++) {
                                        if (!rose_ftimer_running(node->neighbour[i])) {
                                                res = node->neighbour[i];
                                                rose_neigh_hold(node->neighbour[i]);
                                                goto out;
                                        }
                                        failed = 1;
                                }
                        }
                }
        }

        if (failed) {
                *cause      = ROSE_OUT_OF_ORDER;
                *diagnostic = 0;
        } else {
                *cause      = ROSE_NOT_OBTAINABLE;
                *diagnostic = 0;
        }

out:
        if (!route_frame) spin_unlock_bh(&rose_node_list_lock);
        return res;
}

/*
 *      Handle the ioctls that control the routing functions.
 */
int rose_rt_ioctl(unsigned int cmd, void __user *arg)
{
        struct rose_route_struct rose_route;
        struct net_device *dev;
        int err;

        switch (cmd) {
        case SIOCADDRT:
                if (copy_from_user(&rose_route, arg, sizeof(struct rose_route_struct)))
                        return -EFAULT;
                if ((dev = rose_ax25_dev_find(rose_route.device)) == NULL)
                        return -EINVAL;
                if (rose_dev_exists(&rose_route.address)) /* Can't add routes to ourself */
                        return -EINVAL;
                if (rose_route.mask > 10) /* Mask can't be more than 10 digits */
                        return -EINVAL;
                if (rose_route.ndigis > AX25_MAX_DIGIS)
                        return -EINVAL;
                err = rose_add_node(&rose_route, dev);
                return err;

        case SIOCDELRT:
                if (copy_from_user(&rose_route, arg, sizeof(struct rose_route_struct)))
                        return -EFAULT;
                if ((dev = rose_ax25_dev_find(rose_route.device)) == NULL)
                        return -EINVAL;
                err = rose_del_node(&rose_route, dev);
                return err;

        case SIOCRSCLRRT:
                return rose_clear_routes();

        default:
                return -EINVAL;
        }

        return 0;
}

static void rose_del_route_by_neigh(struct rose_neigh *rose_neigh)
{
        struct rose_route *rose_route, *s;

        rose_neigh->restarted = 0;

        rose_stop_t0timer(rose_neigh);
        rose_start_ftimer(rose_neigh);

        skb_queue_purge(&rose_neigh->queue);

        spin_lock_bh(&rose_route_list_lock);

        rose_route = rose_route_list;

        while (rose_route != NULL) {
                if ((rose_route->neigh1 == rose_neigh && rose_route->neigh2 == rose_neigh) ||
                    (rose_route->neigh1 == rose_neigh && rose_route->neigh2 == NULL)       ||
                    (rose_route->neigh2 == rose_neigh && rose_route->neigh1 == NULL)) {
                        s = rose_route->next;
                        rose_remove_route(rose_route);
                        rose_route = s;
                        continue;
                }

                if (rose_route->neigh1 == rose_neigh) {
                        rose_neigh_put(rose_route->neigh1);
                        rose_route->neigh1 = NULL;
                        rose_transmit_clear_request(rose_route->neigh2, rose_route->lci2, ROSE_OUT_OF_ORDER, 0);
                }

                if (rose_route->neigh2 == rose_neigh) {
                        rose_neigh_put(rose_route->neigh2);
                        rose_route->neigh2 = NULL;
                        rose_transmit_clear_request(rose_route->neigh1, rose_route->lci1, ROSE_OUT_OF_ORDER, 0);
                }

                rose_route = rose_route->next;
        }
        spin_unlock_bh(&rose_route_list_lock);
}

/*
 *      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. Blow away all through
 *      routes and connections using this route.
 */
void rose_link_failed(ax25_cb *ax25, int reason)
{
        struct rose_neigh *rose_neigh;

        spin_lock_bh(&rose_neigh_list_lock);
        rose_neigh = rose_neigh_list;
        while (rose_neigh != NULL) {
                if (rose_neigh->ax25 == ax25)
                        break;
                rose_neigh = rose_neigh->next;
        }

        if (rose_neigh != NULL) {
                rose_neigh->ax25 = NULL;
                ax25_cb_put(ax25);

                rose_del_route_by_neigh(rose_neigh);
                rose_kill_by_neigh(rose_neigh);
        }
        spin_unlock_bh(&rose_neigh_list_lock);
}

/*
 *      A device has been "downed" remove its link status. Blow away all
 *      through routes and connections that use this device.
 */
void rose_link_device_down(struct net_device *dev)
{
        struct rose_neigh *rose_neigh;

        for (rose_neigh = rose_neigh_list; rose_neigh != NULL; rose_neigh = rose_neigh->next) {
                if (rose_neigh->dev == dev) {
                        rose_del_route_by_neigh(rose_neigh);
                        rose_kill_by_neigh(rose_neigh);
                }
        }
}

/*
 *      Route a frame to an appropriate AX.25 connection.
 *      A NULL ax25_cb indicates an internally generated frame.
 */
int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
{
        struct rose_neigh *rose_neigh, *new_neigh;
        struct rose_route *rose_route;
        struct rose_facilities_struct facilities;
        rose_address *src_addr, *dest_addr;
        struct sock *sk;
        unsigned short frametype;
        unsigned int lci, new_lci;
        unsigned char cause, diagnostic;
        struct net_device *dev;
        int res = 0;
        char buf[11];

        if (skb->len < ROSE_MIN_LEN)
                return res;

        if (!ax25)
                return rose_loopback_queue(skb, NULL);

        frametype = skb->data[2];
        lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
        if (frametype == ROSE_CALL_REQUEST &&
            (skb->len <= ROSE_CALL_REQ_FACILITIES_OFF ||
             skb->data[ROSE_CALL_REQ_ADDR_LEN_OFF] !=
             ROSE_CALL_REQ_ADDR_LEN_VAL))
                return res;
        src_addr  = (rose_address *)(skb->data + ROSE_CALL_REQ_SRC_ADDR_OFF);
        dest_addr = (rose_address *)(skb->data + ROSE_CALL_REQ_DEST_ADDR_OFF);

        spin_lock_bh(&rose_neigh_list_lock);
        spin_lock_bh(&rose_route_list_lock);

        rose_neigh = rose_neigh_list;
        while (rose_neigh != NULL) {
                if (ax25cmp(&ax25->dest_addr, &rose_neigh->callsign) == 0 &&
                    ax25->ax25_dev->dev == rose_neigh->dev)
                        break;
                rose_neigh = rose_neigh->next;
        }

        if (rose_neigh == NULL) {
                printk("rose_route : unknown neighbour or device %s\n",
                       ax2asc(buf, &ax25->dest_addr));
                goto out;
        }

        /*
         *      Obviously the link is working, halt the ftimer.
         */
        rose_stop_ftimer(rose_neigh);

        /*
         *      LCI of zero is always for us, and its always a restart
         *      frame.
         */
        if (lci == 0) {
                rose_link_rx_restart(skb, rose_neigh, frametype);
                goto out;
        }

        /*
         *      Find an existing socket.
         */
        if ((sk = rose_find_socket(lci, rose_neigh)) != NULL) {
                if (frametype == ROSE_CALL_REQUEST) {
                        struct rose_sock *rose = rose_sk(sk);

                        /* Remove an existing unused socket */
                        rose_clear_queues(sk);
                        rose->cause      = ROSE_NETWORK_CONGESTION;
                        rose->diagnostic = 0;
                        rose_neigh_put(rose->neighbour);
                        rose->neighbour  = NULL;
                        rose->lci        = 0;
                        rose->state      = ROSE_STATE_0;
                        sk->sk_state     = TCP_CLOSE;
                        sk->sk_err       = 0;
                        sk->sk_shutdown  |= SEND_SHUTDOWN;
                        if (!sock_flag(sk, SOCK_DEAD)) {
                                sk->sk_state_change(sk);
                                sock_set_flag(sk, SOCK_DEAD);
                        }
                }
                else {
                        skb_reset_transport_header(skb);
                        res = rose_process_rx_frame(sk, skb);
                        goto out;
                }
        }

        /*
         *      Is is a Call Request and is it for us ?
         */
        if (frametype == ROSE_CALL_REQUEST)
                if ((dev = rose_dev_get(dest_addr)) != NULL) {
                        res = rose_rx_call_request(skb, dev, rose_neigh, lci);
                        dev_put(dev);
                        goto out;
                }

        if (!sysctl_rose_routing_control) {
                rose_transmit_clear_request(rose_neigh, lci, ROSE_NOT_OBTAINABLE, 0);
                goto out;
        }

        /*
         *      Route it to the next in line if we have an entry for it.
         */
        rose_route = rose_route_list;
        while (rose_route != NULL) {
                if (rose_route->lci1 == lci &&
                    rose_route->neigh1 == rose_neigh) {
                        if (frametype == ROSE_CALL_REQUEST) {
                                /* F6FBB - Remove an existing unused route */
                                rose_remove_route(rose_route);
                                break;
                        } else if (rose_route->neigh2 != NULL) {
                                skb->data[0] &= 0xF0;
                                skb->data[0] |= (rose_route->lci2 >> 8) & 0x0F;
                                skb->data[1]  = (rose_route->lci2 >> 0) & 0xFF;
                                rose_transmit_link(skb, rose_route->neigh2);
                                if (frametype == ROSE_CLEAR_CONFIRMATION)
                                        rose_remove_route(rose_route);
                                res = 1;
                                goto out;
                        } else {
                                if (frametype == ROSE_CLEAR_CONFIRMATION)
                                        rose_remove_route(rose_route);
                                goto out;
                        }
                }
                if (rose_route->lci2 == lci &&
                    rose_route->neigh2 == rose_neigh) {
                        if (frametype == ROSE_CALL_REQUEST) {
                                /* F6FBB - Remove an existing unused route */
                                rose_remove_route(rose_route);
                                break;
                        } else if (rose_route->neigh1 != NULL) {
                                skb->data[0] &= 0xF0;
                                skb->data[0] |= (rose_route->lci1 >> 8) & 0x0F;
                                skb->data[1]  = (rose_route->lci1 >> 0) & 0xFF;
                                rose_transmit_link(skb, rose_route->neigh1);
                                if (frametype == ROSE_CLEAR_CONFIRMATION)
                                        rose_remove_route(rose_route);
                                res = 1;
                                goto out;
                        } else {
                                if (frametype == ROSE_CLEAR_CONFIRMATION)
                                        rose_remove_route(rose_route);
                                goto out;
                        }
                }
                rose_route = rose_route->next;
        }

        /*
         *      We know that:
         *      1. The frame isn't for us,
         *      2. It isn't "owned" by any existing route.
         */
        if (frametype != ROSE_CALL_REQUEST) {   /* XXX */
                res = 0;
                goto out;
        }

        memset(&facilities, 0x00, sizeof(struct rose_facilities_struct));

        if (!rose_parse_facilities(skb->data + ROSE_CALL_REQ_FACILITIES_OFF,
                                   skb->len - ROSE_CALL_REQ_FACILITIES_OFF,
                                   &facilities)) {
                rose_transmit_clear_request(rose_neigh, lci, ROSE_INVALID_FACILITY, 76);
                goto out;
        }

        /*
         *      Check for routing loops.
         */
        rose_route = rose_route_list;
        while (rose_route != NULL) {
                if (rose_route->rand == facilities.rand &&
                    rosecmp(src_addr, &rose_route->src_addr) == 0 &&
                    ax25cmp(&facilities.dest_call, &rose_route->src_call) == 0 &&
                    ax25cmp(&facilities.source_call, &rose_route->dest_call) == 0) {
                        rose_transmit_clear_request(rose_neigh, lci, ROSE_NOT_OBTAINABLE, 120);
                        goto out;
                }
                rose_route = rose_route->next;
        }

        if ((new_neigh = rose_get_neigh(dest_addr, &cause, &diagnostic, 1)) == NULL) {
                rose_transmit_clear_request(rose_neigh, lci, cause, diagnostic);
                goto out;
        }

        if ((new_lci = rose_new_lci(new_neigh)) == 0) {
                rose_transmit_clear_request(rose_neigh, lci, ROSE_NETWORK_CONGESTION, 71);
                goto put_neigh;
        }

        if ((rose_route = kmalloc_obj(*rose_route, GFP_ATOMIC)) == NULL) {
                rose_transmit_clear_request(rose_neigh, lci, ROSE_NETWORK_CONGESTION, 120);
                goto put_neigh;
        }

        rose_route->lci1      = lci;
        rose_route->src_addr  = *src_addr;
        rose_route->dest_addr = *dest_addr;
        rose_route->src_call  = facilities.dest_call;
        rose_route->dest_call = facilities.source_call;
        rose_route->rand      = facilities.rand;
        rose_route->neigh1    = rose_neigh;
        rose_route->lci2      = new_lci;
        rose_route->neigh2    = new_neigh;

        rose_neigh_hold(rose_route->neigh1);
        rose_neigh_hold(rose_route->neigh2);

        rose_route->next = rose_route_list;
        rose_route_list  = rose_route;

        skb->data[0] &= 0xF0;
        skb->data[0] |= (rose_route->lci2 >> 8) & 0x0F;
        skb->data[1]  = (rose_route->lci2 >> 0) & 0xFF;

        rose_transmit_link(skb, rose_route->neigh2);
        res = 1;

put_neigh:
        rose_neigh_put(new_neigh);
out:
        spin_unlock_bh(&rose_route_list_lock);
        spin_unlock_bh(&rose_neigh_list_lock);

        return res;
}

#ifdef CONFIG_PROC_FS

static void *rose_node_start(struct seq_file *seq, loff_t *pos)
        __acquires(rose_node_list_lock)
{
        struct rose_node *rose_node;
        int i = 1;

        spin_lock_bh(&rose_node_list_lock);
        if (*pos == 0)
                return SEQ_START_TOKEN;

        for (rose_node = rose_node_list; rose_node && i < *pos;
             rose_node = rose_node->next, ++i);

        return (i == *pos) ? rose_node : NULL;
}

static void *rose_node_next(struct seq_file *seq, void *v, loff_t *pos)
{
        ++*pos;

        return (v == SEQ_START_TOKEN) ? rose_node_list
                : ((struct rose_node *)v)->next;
}

static void rose_node_stop(struct seq_file *seq, void *v)
        __releases(rose_node_list_lock)
{
        spin_unlock_bh(&rose_node_list_lock);
}

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

        if (v == SEQ_START_TOKEN)
                seq_puts(seq, "address    mask n neigh neigh neigh\n");
        else {
                const struct rose_node *rose_node = v;
                seq_printf(seq, "%-10s %04d %d",
                           rose2asc(rsbuf, &rose_node->address),
                           rose_node->mask,
                           rose_node->count);

                for (i = 0; i < rose_node->count; i++)
                        seq_printf(seq, " %05d", rose_node->neighbour[i]->number);

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

const struct seq_operations rose_node_seqops = {
        .start = rose_node_start,
        .next = rose_node_next,
        .stop = rose_node_stop,
        .show = rose_node_show,
};

static void *rose_neigh_start(struct seq_file *seq, loff_t *pos)
        __acquires(rose_neigh_list_lock)
{
        struct rose_neigh *rose_neigh;
        int i = 1;

        spin_lock_bh(&rose_neigh_list_lock);
        if (*pos == 0)
                return SEQ_START_TOKEN;

        for (rose_neigh = rose_neigh_list; rose_neigh && i < *pos;
             rose_neigh = rose_neigh->next, ++i);

        return (i == *pos) ? rose_neigh : NULL;
}

static void *rose_neigh_next(struct seq_file *seq, void *v, loff_t *pos)
{
        ++*pos;

        return (v == SEQ_START_TOKEN) ? rose_neigh_list
                : ((struct rose_neigh *)v)->next;
}

static void rose_neigh_stop(struct seq_file *seq, void *v)
        __releases(rose_neigh_list_lock)
{
        spin_unlock_bh(&rose_neigh_list_lock);
}

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

        if (v == SEQ_START_TOKEN)
                seq_puts(seq,
                         "addr  callsign  dev  count use mode restart  t0  tf digipeaters\n");
        else {
                struct rose_neigh *rose_neigh = v;

                /* if (!rose_neigh->loopback) { */
                seq_printf(seq, "%05d %-9s %-4s   %3d %3d  %3s     %3s %3lu %3lu",
                           rose_neigh->number,
                           (rose_neigh->loopback) ? "RSLOOP-0" : ax2asc(buf, &rose_neigh->callsign),
                           rose_neigh->dev ? rose_neigh->dev->name : "???",
                           rose_neigh->count,
                           refcount_read(&rose_neigh->use) - rose_neigh->count - 1,
                           (rose_neigh->dce_mode) ? "DCE" : "DTE",
                           (rose_neigh->restarted) ? "yes" : "no",
                           ax25_display_timer(&rose_neigh->t0timer) / HZ,
                           ax25_display_timer(&rose_neigh->ftimer)  / HZ);

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

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


const struct seq_operations rose_neigh_seqops = {
        .start = rose_neigh_start,
        .next = rose_neigh_next,
        .stop = rose_neigh_stop,
        .show = rose_neigh_show,
};

static void *rose_route_start(struct seq_file *seq, loff_t *pos)
        __acquires(rose_route_list_lock)
{
        struct rose_route *rose_route;
        int i = 1;

        spin_lock_bh(&rose_route_list_lock);
        if (*pos == 0)
                return SEQ_START_TOKEN;

        for (rose_route = rose_route_list; rose_route && i < *pos;
             rose_route = rose_route->next, ++i);

        return (i == *pos) ? rose_route : NULL;
}

static void *rose_route_next(struct seq_file *seq, void *v, loff_t *pos)
{
        ++*pos;

        return (v == SEQ_START_TOKEN) ? rose_route_list
                : ((struct rose_route *)v)->next;
}

static void rose_route_stop(struct seq_file *seq, void *v)
        __releases(rose_route_list_lock)
{
        spin_unlock_bh(&rose_route_list_lock);
}

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

        if (v == SEQ_START_TOKEN)
                seq_puts(seq,
                         "lci  address     callsign   neigh  <-> lci  address     callsign   neigh\n");
        else {
                struct rose_route *rose_route = v;

                if (rose_route->neigh1)
                        seq_printf(seq,
                                   "%3.3X  %-10s  %-9s  %05d      ",
                                   rose_route->lci1,
                                   rose2asc(rsbuf, &rose_route->src_addr),
                                   ax2asc(buf, &rose_route->src_call),
                                   rose_route->neigh1->number);
                else
                        seq_puts(seq,
                                 "000  *           *          00000      ");

                if (rose_route->neigh2)
                        seq_printf(seq,
                                   "%3.3X  %-10s  %-9s  %05d\n",
                                   rose_route->lci2,
                                   rose2asc(rsbuf, &rose_route->dest_addr),
                                   ax2asc(buf, &rose_route->dest_call),
                                   rose_route->neigh2->number);
                 else
                         seq_puts(seq,
                                  "000  *           *          00000\n");
                }
        return 0;
}

struct seq_operations rose_route_seqops = {
        .start = rose_route_start,
        .next = rose_route_next,
        .stop = rose_route_stop,
        .show = rose_route_show,
};
#endif /* CONFIG_PROC_FS */

/*
 *      Release all memory associated with ROSE routing structures.
 */
void __exit rose_rt_free(void)
{
        struct rose_neigh *s, *rose_neigh = rose_neigh_list;
        struct rose_node  *t, *rose_node  = rose_node_list;
        struct rose_route *u, *rose_route = rose_route_list;
        int i;

        while (rose_neigh != NULL) {
                s          = rose_neigh;
                rose_neigh = rose_neigh->next;

                rose_remove_neigh(s);
                rose_neigh_put(s);
        }

        while (rose_node != NULL) {
                t         = rose_node;
                rose_node = rose_node->next;

                for (i = 0; i < t->count; i++)
                        rose_neigh_put(t->neighbour[i]);
                rose_remove_node(t);
        }

        while (rose_route != NULL) {
                u          = rose_route;
                rose_route = rose_route->next;

                rose_remove_route(u);
        }
}