hdlc_raw_eth.c

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/*
 * Generic HDLC support routines for Linux
 * HDLC Ethernet emulation support
 *
 * Copyright (C) 2002-2006 Krzysztof Halasa <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 */

#include <linux/errno.h>
#include <linux/etherdevice.h>
#include <linux/gfp.h>
#include <linux/hdlc.h>
#include <linux/if_arp.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pkt_sched.h>
#include <linux/poll.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>

static int raw_eth_ioctl(struct net_device *dev, struct ifreq *ifr);

static netdev_tx_t eth_tx(struct sk_buff *skb, struct net_device *dev)
{
    int pad = ETH_ZLEN - skb->len;
    if (pad > 0) {      /* Pad the frame with zeros */
        int len = skb->len;
        if (skb_tailroom(skb) < pad)
            if (pskb_expand_head(skb, 0, pad, GFP_ATOMIC)) {
                dev->stats.tx_dropped++;
                dev_kfree_skb(skb);
                return 0;
            }
        skb_put(skb, pad);
        memset(skb->data + len, 0, pad);
    }
    return dev_to_hdlc(dev)->xmit(skb, dev);
}


static struct hdlc_proto proto = {
    .type_trans = eth_type_trans,
    .xmit       = eth_tx,
    .ioctl      = raw_eth_ioctl,
    .module     = THIS_MODULE,
};


static int raw_eth_ioctl(struct net_device *dev, struct ifreq *ifr)
{
    raw_hdlc_proto __user *raw_s = ifr->ifr_settings.ifs_ifsu.raw_hdlc;
    const size_t size = sizeof(raw_hdlc_proto);
    raw_hdlc_proto new_settings;
    hdlc_device *hdlc = dev_to_hdlc(dev);
    int result, old_qlen;

    switch (ifr->ifr_settings.type) {
    case IF_GET_PROTO:
        if (dev_to_hdlc(dev)->proto != &proto)
            return -EINVAL;
        ifr->ifr_settings.type = IF_PROTO_HDLC_ETH;
        if (ifr->ifr_settings.size < size) {
            ifr->ifr_settings.size = size; /* data size wanted */
            return -ENOBUFS;
        }
        if (copy_to_user(raw_s, hdlc->state, size))
            return -EFAULT;
        return 0;

    case IF_PROTO_HDLC_ETH:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;

        if (dev->flags & IFF_UP)
            return -EBUSY;

        if (copy_from_user(&new_settings, raw_s, size))
            return -EFAULT;

        if (new_settings.encoding == ENCODING_DEFAULT)
            new_settings.encoding = ENCODING_NRZ;

        if (new_settings.parity == PARITY_DEFAULT)
            new_settings.parity = PARITY_CRC16_PR1_CCITT;

        result = hdlc->attach(dev, new_settings.encoding,
                      new_settings.parity);
        if (result)
            return result;

        result = attach_hdlc_protocol(dev, &proto,
                          sizeof(raw_hdlc_proto));
        if (result)
            return result;
        memcpy(hdlc->state, &new_settings, size);
        old_qlen = dev->tx_queue_len;
        ether_setup(dev);
        dev->tx_queue_len = old_qlen;
        eth_hw_addr_random(dev);
        netif_dormant_off(dev);
        return 0;
    }

    return -EINVAL;
}


static int __init mod_init(void)
{
    register_hdlc_protocol(&proto);
    return 0;
}



static void __exit mod_exit(void)
{
    unregister_hdlc_protocol(&proto);
}


module_init(mod_init);
module_exit(mod_exit);

MODULE_AUTHOR("Krzysztof Halasa <[email protected]>");
MODULE_DESCRIPTION("Ethernet encapsulation support for generic HDLC");
MODULE_LICENSE("GPL v2");