nr_dev.c

Go to the documentation of this file.

/*
 * 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 ([email protected])
 */
#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 <asm/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;
}

#ifdef CONFIG_INET

static int nr_rebuild_header(struct sk_buff *skb)
{
    unsigned char *bp = skb->data;

    if (arp_find(bp + 7, skb))
        return 1;

    bp[6] &= ~AX25_CBIT;
    bp[6] &= ~AX25_EBIT;
    bp[6] |= AX25_SSSID_SPARE;
    bp    += AX25_ADDR_LEN;

    bp[6] &= ~AX25_CBIT;
    bp[6] |= AX25_EBIT;
    bp[6] |= AX25_SSSID_SPARE;

    return 0;
}

#else

static int nr_rebuild_header(struct sk_buff *skb)
{
    return 1;
}

#endif

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++ = 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((ax25_address *)dev->dev_addr, NULL);
    }

    memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);

    return 0;
}

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

    err = ax25_listen_register((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((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,
    .rebuild= nr_rebuild_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;
}