// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 */
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/sysctl.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/in.h>
#include <linux/if_ether.h>     /* For the statistics structure. */
#include <linux/slab.h>
#include <linux/uaccess.h>

#include <asm/io.h>

#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>

#include <net/ip.h>
#include <net/arp.h>

#include <net/ax25.h>
#include <net/netrom.h>

/*
 *      Only allow IP over NET/ROM frames through if the netrom device is up.
 */

int nr_rx_ip(struct sk_buff *skb, struct net_device *dev)
{
        struct net_device_stats *stats = &dev->stats;

        if (!netif_running(dev)) {
                stats->rx_dropped++;
                return 0;
        }

        stats->rx_packets++;
        stats->rx_bytes += skb->len;

        skb->protocol = htons(ETH_P_IP);

        /* Spoof incoming device */
        skb->dev      = dev;
        skb->mac_header = skb->network_header;
        skb_reset_network_header(skb);
        skb->pkt_type = PACKET_HOST;

        netif_rx(skb);

        return 1;
}

static int nr_header(struct sk_buff *skb, struct net_device *dev,
                     unsigned short type,
                     const void *daddr, const void *saddr, unsigned int len)
{
        unsigned char *buff = skb_push(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);

        memcpy(buff, (saddr != NULL) ? saddr : dev->dev_addr, dev->addr_len);
        buff[6] &= ~AX25_CBIT;
        buff[6] &= ~AX25_EBIT;
        buff[6] |= AX25_SSSID_SPARE;
        buff    += AX25_ADDR_LEN;

        if (daddr != NULL)
                memcpy(buff, daddr, dev->addr_len);
        buff[6] &= ~AX25_CBIT;
        buff[6] |= AX25_EBIT;
        buff[6] |= AX25_SSSID_SPARE;
        buff    += AX25_ADDR_LEN;

        *buff++ = READ_ONCE(sysctl_netrom_network_ttl_initialiser);

        *buff++ = NR_PROTO_IP;
        *buff++ = NR_PROTO_IP;
        *buff++ = 0;
        *buff++ = 0;
        *buff++ = NR_PROTOEXT;

        if (daddr != NULL)
                return 37;

        return -37;
}

static int __must_check nr_set_mac_address(struct net_device *dev, void *addr)
{
        struct sockaddr *sa = addr;
        int err;

        if (!memcmp(dev->dev_addr, sa->sa_data, dev->addr_len))
                return 0;

        if (dev->flags & IFF_UP) {
                err = ax25_listen_register((ax25_address *)sa->sa_data, NULL);
                if (err)
                        return err;

                ax25_listen_release((const ax25_address *)dev->dev_addr, NULL);
        }

        dev_addr_set(dev, sa->sa_data);

        return 0;
}

static int nr_open(struct net_device *dev)
{
        int err;

        err = ax25_listen_register((const ax25_address *)dev->dev_addr, NULL);
        if (err)
                return err;

        netif_start_queue(dev);

        return 0;
}

static int nr_close(struct net_device *dev)
{
        ax25_listen_release((const ax25_address *)dev->dev_addr, NULL);
        netif_stop_queue(dev);
        return 0;
}

static netdev_tx_t nr_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct net_device_stats *stats = &dev->stats;
        unsigned int len = skb->len;

        if (!nr_route_frame(skb, NULL)) {
                kfree_skb(skb);
                stats->tx_errors++;
                return NETDEV_TX_OK;
        }

        stats->tx_packets++;
        stats->tx_bytes += len;

        return NETDEV_TX_OK;
}

static const struct header_ops nr_header_ops = {
        .create = nr_header,
};

static const struct net_device_ops nr_netdev_ops = {
        .ndo_open               = nr_open,
        .ndo_stop               = nr_close,
        .ndo_start_xmit         = nr_xmit,
        .ndo_set_mac_address    = nr_set_mac_address,
};

void nr_setup(struct net_device *dev)
{
        dev->mtu                = NR_MAX_PACKET_SIZE;
        dev->netdev_ops         = &nr_netdev_ops;
        dev->header_ops         = &nr_header_ops;
        dev->hard_header_len    = NR_NETWORK_LEN + NR_TRANSPORT_LEN;
        dev->addr_len           = AX25_ADDR_LEN;
        dev->type               = ARPHRD_NETROM;

        /* New-style flags. */
        dev->flags              = IFF_NOARP;
}