/*
 *      X.25 Packet Layer release 002
 *
 *      This is ALPHA test software. This code may break your machine,
 *      randomly fail to work with new releases, misbehave and/or generally
 *      screw up. It might even work.
 *
 *      This code REQUIRES 2.1.15 or higher
 *
 *      This module:
 *              This module 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.
 *
 *      History
 *      X.25 001        Jonathan Naylor Started coding.
 */

#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/x25.h>

LIST_HEAD(x25_route_list);
DEFINE_RWLOCK(x25_route_list_lock);

/*
 *      Add a new route.
 */
static int x25_add_route(struct x25_address *address, unsigned int sigdigits,
                         struct net_device *dev)
{
        struct x25_route *rt;
        struct list_head *entry;
        int rc = -EINVAL;

        write_lock_bh(&x25_route_list_lock);

        list_for_each(entry, &x25_route_list) {
                rt = list_entry(entry, struct x25_route, node);

                if (!memcmp(&rt->address, address, sigdigits) &&
                    rt->sigdigits == sigdigits)
                        goto out;
        }

        rt = kmalloc(sizeof(*rt), GFP_ATOMIC);
        rc = -ENOMEM;
        if (!rt)
                goto out;

        strcpy(rt->address.x25_addr, "000000000000000");
        memcpy(rt->address.x25_addr, address->x25_addr, sigdigits);

        rt->sigdigits = sigdigits;
        rt->dev       = dev;
        refcount_set(&rt->refcnt, 1);

        list_add(&rt->node, &x25_route_list);
        rc = 0;
out:
        write_unlock_bh(&x25_route_list_lock);
        return rc;
}

/**
 * __x25_remove_route - remove route from x25_route_list
 * @rt: route to remove
 *
 * Remove route from x25_route_list. If it was there.
 * Caller must hold x25_route_list_lock.
 */
static void __x25_remove_route(struct x25_route *rt)
{
        if (rt->node.next) {
                list_del(&rt->node);
                x25_route_put(rt);
        }
}

static int x25_del_route(struct x25_address *address, unsigned int sigdigits,
                         struct net_device *dev)
{
        struct x25_route *rt;
        struct list_head *entry;
        int rc = -EINVAL;

        write_lock_bh(&x25_route_list_lock);

        list_for_each(entry, &x25_route_list) {
                rt = list_entry(entry, struct x25_route, node);

                if (!memcmp(&rt->address, address, sigdigits) &&
                    rt->sigdigits == sigdigits && rt->dev == dev) {
                        __x25_remove_route(rt);
                        rc = 0;
                        break;
                }
        }

        write_unlock_bh(&x25_route_list_lock);
        return rc;
}

/*
 *      A device has been removed, remove its routes.
 */
void x25_route_device_down(struct net_device *dev)
{
        struct x25_route *rt;
        struct list_head *entry, *tmp;

        write_lock_bh(&x25_route_list_lock);

        list_for_each_safe(entry, tmp, &x25_route_list) {
                rt = list_entry(entry, struct x25_route, node);

                if (rt->dev == dev)
                        __x25_remove_route(rt);
        }
        write_unlock_bh(&x25_route_list_lock);

        /* Remove any related forwarding */
        x25_clear_forward_by_dev(dev);
}

/*
 *      Check that the device given is a valid X.25 interface that is "up".
 */
struct net_device *x25_dev_get(char *devname)
{
        struct net_device *dev = dev_get_by_name(&init_net, devname);

        if (dev &&
            (!(dev->flags & IFF_UP) || (dev->type != ARPHRD_X25
#if IS_ENABLED(CONFIG_LLC)
                                        && dev->type != ARPHRD_ETHER
#endif
                                        ))){
                dev_put(dev);
                dev = NULL;
        }

        return dev;
}

/**
 *      x25_get_route - Find a route given an X.25 address.
 *      @addr - address to find a route for
 *
 *      Find a route given an X.25 address.
 */
struct x25_route *x25_get_route(struct x25_address *addr)
{
        struct x25_route *rt, *use = NULL;
        struct list_head *entry;

        read_lock_bh(&x25_route_list_lock);

        list_for_each(entry, &x25_route_list) {
                rt = list_entry(entry, struct x25_route, node);

                if (!memcmp(&rt->address, addr, rt->sigdigits)) {
                        if (!use)
                                use = rt;
                        else if (rt->sigdigits > use->sigdigits)
                                use = rt;
                }
        }

        if (use)
                x25_route_hold(use);

        read_unlock_bh(&x25_route_list_lock);
        return use;
}

/*
 *      Handle the ioctls that control the routing functions.
 */
int x25_route_ioctl(unsigned int cmd, void __user *arg)
{
        struct x25_route_struct rt;
        struct net_device *dev;
        int rc = -EINVAL;

        if (cmd != SIOCADDRT && cmd != SIOCDELRT)
                goto out;

        rc = -EFAULT;
        if (copy_from_user(&rt, arg, sizeof(rt)))
                goto out;

        rc = -EINVAL;
        if (rt.sigdigits > 15)
                goto out;

        dev = x25_dev_get(rt.device);
        if (!dev)
                goto out;

        if (cmd == SIOCADDRT)
                rc = x25_add_route(&rt.address, rt.sigdigits, dev);
        else
                rc = x25_del_route(&rt.address, rt.sigdigits, dev);
        dev_put(dev);
out:
        return rc;
}

/*
 *      Release all memory associated with X.25 routing structures.
 */
void __exit x25_route_free(void)
{
        struct x25_route *rt;
        struct list_head *entry, *tmp;

        write_lock_bh(&x25_route_list_lock);
        list_for_each_safe(entry, tmp, &x25_route_list) {
                rt = list_entry(entry, struct x25_route, node);
                __x25_remove_route(rt);
        }
        write_unlock_bh(&x25_route_list_lock);
}