// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright (C) Steven Whitehouse GW7RRM (stevew@acm.org)
 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
 * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
 * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
 */

#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/timer.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.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 <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/export.h>

static ax25_route *ax25_route_list;
DEFINE_RWLOCK(ax25_route_lock);

void ax25_rt_device_down(struct net_device *dev)
{
        ax25_route *s, *t, *ax25_rt;

        write_lock_bh(&ax25_route_lock);
        ax25_rt = ax25_route_list;
        while (ax25_rt != NULL) {
                s       = ax25_rt;
                ax25_rt = ax25_rt->next;

                if (s->dev == dev) {
                        if (ax25_route_list == s) {
                                ax25_route_list = s->next;
                                kfree(s->digipeat);
                                kfree(s);
                        } else {
                                for (t = ax25_route_list; t != NULL; t = t->next) {
                                        if (t->next == s) {
                                                t->next = s->next;
                                                kfree(s->digipeat);
                                                kfree(s);
                                                break;
                                        }
                                }
                        }
                }
        }
        write_unlock_bh(&ax25_route_lock);
}

static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
{
        ax25_route *ax25_rt;
        ax25_dev *ax25_dev;
        int i;

        if (route->digi_count > AX25_MAX_DIGIS)
                return -EINVAL;

        ax25_dev = ax25_addr_ax25dev(&route->port_addr);
        if (!ax25_dev)
                return -EINVAL;

        write_lock_bh(&ax25_route_lock);

        ax25_rt = ax25_route_list;
        while (ax25_rt != NULL) {
                if (ax25cmp(&ax25_rt->callsign, &route->dest_addr) == 0 &&
                            ax25_rt->dev == ax25_dev->dev) {
                        kfree(ax25_rt->digipeat);
                        ax25_rt->digipeat = NULL;
                        if (route->digi_count != 0) {
                                if ((ax25_rt->digipeat = kmalloc_obj(ax25_digi, GFP_ATOMIC)) == NULL) {
                                        write_unlock_bh(&ax25_route_lock);
                                        ax25_dev_put(ax25_dev);
                                        return -ENOMEM;
                                }
                                ax25_rt->digipeat->lastrepeat = -1;
                                ax25_rt->digipeat->ndigi      = route->digi_count;
                                for (i = 0; i < route->digi_count; i++) {
                                        ax25_rt->digipeat->repeated[i] = 0;
                                        ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
                                }
                        }
                        write_unlock_bh(&ax25_route_lock);
                        ax25_dev_put(ax25_dev);
                        return 0;
                }
                ax25_rt = ax25_rt->next;
        }

        if ((ax25_rt = kmalloc_obj(ax25_route, GFP_ATOMIC)) == NULL) {
                write_unlock_bh(&ax25_route_lock);
                ax25_dev_put(ax25_dev);
                return -ENOMEM;
        }

        ax25_rt->callsign     = route->dest_addr;
        ax25_rt->dev          = ax25_dev->dev;
        ax25_rt->digipeat     = NULL;
        ax25_rt->ip_mode      = ' ';
        if (route->digi_count != 0) {
                if ((ax25_rt->digipeat = kmalloc_obj(ax25_digi, GFP_ATOMIC)) == NULL) {
                        write_unlock_bh(&ax25_route_lock);
                        kfree(ax25_rt);
                        ax25_dev_put(ax25_dev);
                        return -ENOMEM;
                }
                ax25_rt->digipeat->lastrepeat = -1;
                ax25_rt->digipeat->ndigi      = route->digi_count;
                for (i = 0; i < route->digi_count; i++) {
                        ax25_rt->digipeat->repeated[i] = 0;
                        ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
                }
        }
        ax25_rt->next   = ax25_route_list;
        ax25_route_list = ax25_rt;
        write_unlock_bh(&ax25_route_lock);
        ax25_dev_put(ax25_dev);

        return 0;
}

void __ax25_put_route(ax25_route *ax25_rt)
{
        kfree(ax25_rt->digipeat);
        kfree(ax25_rt);
}

static int ax25_rt_del(struct ax25_routes_struct *route)
{
        ax25_route *s, *t, *ax25_rt;
        ax25_dev *ax25_dev;

        if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
                return -EINVAL;

        write_lock_bh(&ax25_route_lock);

        ax25_rt = ax25_route_list;
        while (ax25_rt != NULL) {
                s       = ax25_rt;
                ax25_rt = ax25_rt->next;
                if (s->dev == ax25_dev->dev &&
                    ax25cmp(&route->dest_addr, &s->callsign) == 0) {
                        if (ax25_route_list == s) {
                                ax25_route_list = s->next;
                                __ax25_put_route(s);
                        } else {
                                for (t = ax25_route_list; t != NULL; t = t->next) {
                                        if (t->next == s) {
                                                t->next = s->next;
                                                __ax25_put_route(s);
                                                break;
                                        }
                                }
                        }
                }
        }
        write_unlock_bh(&ax25_route_lock);
        ax25_dev_put(ax25_dev);

        return 0;
}

static int ax25_rt_opt(struct ax25_route_opt_struct *rt_option)
{
        ax25_route *ax25_rt;
        ax25_dev *ax25_dev;
        int err = 0;

        if ((ax25_dev = ax25_addr_ax25dev(&rt_option->port_addr)) == NULL)
                return -EINVAL;

        write_lock_bh(&ax25_route_lock);

        ax25_rt = ax25_route_list;
        while (ax25_rt != NULL) {
                if (ax25_rt->dev == ax25_dev->dev &&
                    ax25cmp(&rt_option->dest_addr, &ax25_rt->callsign) == 0) {
                        switch (rt_option->cmd) {
                        case AX25_SET_RT_IPMODE:
                                switch (rt_option->arg) {
                                case ' ':
                                case 'D':
                                case 'V':
                                        ax25_rt->ip_mode = rt_option->arg;
                                        break;
                                default:
                                        err = -EINVAL;
                                        goto out;
                                }
                                break;
                        default:
                                err = -EINVAL;
                                goto out;
                        }
                }
                ax25_rt = ax25_rt->next;
        }

out:
        write_unlock_bh(&ax25_route_lock);
        ax25_dev_put(ax25_dev);
        return err;
}

int ax25_rt_ioctl(unsigned int cmd, void __user *arg)
{
        struct ax25_route_opt_struct rt_option;
        struct ax25_routes_struct route;

        switch (cmd) {
        case SIOCADDRT:
                if (copy_from_user(&route, arg, sizeof(route)))
                        return -EFAULT;
                return ax25_rt_add(&route);

        case SIOCDELRT:
                if (copy_from_user(&route, arg, sizeof(route)))
                        return -EFAULT;
                return ax25_rt_del(&route);

        case SIOCAX25OPTRT:
                if (copy_from_user(&rt_option, arg, sizeof(rt_option)))
                        return -EFAULT;
                return ax25_rt_opt(&rt_option);

        default:
                return -EINVAL;
        }
}

#ifdef CONFIG_PROC_FS

static void *ax25_rt_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(ax25_route_lock)
{
        struct ax25_route *ax25_rt;
        int i = 1;

        read_lock(&ax25_route_lock);
        if (*pos == 0)
                return SEQ_START_TOKEN;

        for (ax25_rt = ax25_route_list; ax25_rt != NULL; ax25_rt = ax25_rt->next) {
                if (i == *pos)
                        return ax25_rt;
                ++i;
        }

        return NULL;
}

static void *ax25_rt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        ++*pos;
        return (v == SEQ_START_TOKEN) ? ax25_route_list :
                ((struct ax25_route *) v)->next;
}

static void ax25_rt_seq_stop(struct seq_file *seq, void *v)
        __releases(ax25_route_lock)
{
        read_unlock(&ax25_route_lock);
}

static int ax25_rt_seq_show(struct seq_file *seq, void *v)
{
        char buf[11];

        if (v == SEQ_START_TOKEN)
                seq_puts(seq, "callsign  dev  mode digipeaters\n");
        else {
                struct ax25_route *ax25_rt = v;
                const char *callsign;
                int i;

                if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0)
                        callsign = "default";
                else
                        callsign = ax2asc(buf, &ax25_rt->callsign);

                seq_printf(seq, "%-9s %-4s",
                        callsign,
                        ax25_rt->dev ? ax25_rt->dev->name : "???");

                switch (ax25_rt->ip_mode) {
                case 'V':
                        seq_puts(seq, "   vc");
                        break;
                case 'D':
                        seq_puts(seq, "   dg");
                        break;
                default:
                        seq_puts(seq, "    *");
                        break;
                }

                if (ax25_rt->digipeat != NULL)
                        for (i = 0; i < ax25_rt->digipeat->ndigi; i++)
                                seq_printf(seq, " %s",
                                     ax2asc(buf, &ax25_rt->digipeat->calls[i]));

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

const struct seq_operations ax25_rt_seqops = {
        .start = ax25_rt_seq_start,
        .next = ax25_rt_seq_next,
        .stop = ax25_rt_seq_stop,
        .show = ax25_rt_seq_show,
};
#endif

/*
 *      Find AX.25 route
 *
 *      Only routes with a reference count of zero can be destroyed.
 *      Must be called with ax25_route_lock read locked.
 */
ax25_route *ax25_get_route(ax25_address *addr, struct net_device *dev)
{
        ax25_route *ax25_spe_rt = NULL;
        ax25_route *ax25_def_rt = NULL;
        ax25_route *ax25_rt;

        /*
         *      Bind to the physical interface we heard them on, or the default
         *      route if none is found;
         */
        for (ax25_rt = ax25_route_list; ax25_rt != NULL; ax25_rt = ax25_rt->next) {
                if (dev == NULL) {
                        if (ax25cmp(&ax25_rt->callsign, addr) == 0 && ax25_rt->dev != NULL)
                                ax25_spe_rt = ax25_rt;
                        if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0 && ax25_rt->dev != NULL)
                                ax25_def_rt = ax25_rt;
                } else {
                        if (ax25cmp(&ax25_rt->callsign, addr) == 0 && ax25_rt->dev == dev)
                                ax25_spe_rt = ax25_rt;
                        if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0 && ax25_rt->dev == dev)
                                ax25_def_rt = ax25_rt;
                }
        }

        ax25_rt = ax25_def_rt;
        if (ax25_spe_rt != NULL)
                ax25_rt = ax25_spe_rt;

        return ax25_rt;
}


struct sk_buff *ax25_rt_build_path(struct sk_buff *skb, ax25_address *src,
        ax25_address *dest, ax25_digi *digi)
{
        unsigned char *bp;
        int len;

        len = digi->ndigi * AX25_ADDR_LEN;

        if (unlikely(skb_headroom(skb) < len)) {
                skb = skb_expand_head(skb, len);
                if (!skb) {
                        printk(KERN_CRIT "AX.25: ax25_dg_build_path - out of memory\n");
                        return NULL;
                }
        }

        bp = skb_push(skb, len);

        ax25_addr_build(bp, src, dest, digi, AX25_COMMAND, AX25_MODULUS);

        return skb;
}

/*
 *      Free all memory associated with routing structures.
 */
void __exit ax25_rt_free(void)
{
        ax25_route *s, *ax25_rt = ax25_route_list;

        write_lock_bh(&ax25_route_lock);
        while (ax25_rt != NULL) {
                s       = ax25_rt;
                ax25_rt = ax25_rt->next;

                kfree(s->digipeat);
                kfree(s);
        }
        write_unlock_bh(&ax25_route_lock);
}