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/*

 *      G8BPQ compatible "AX.25 via ethernet" driver release 003

 *

 *      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 2.0.0 or higher/ NET3.029

 *

 *      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.

 *

 *      This is a "pseudo" network driver to allow AX.25 over Ethernet

 *      using G8BPQ encapsulation. It has been extracted from the protocol

 *      implementation because

 *

 *              - things got unreadable within the protocol stack

 *              - to cure the protocol stack from "feature-ism"

 *              - a protocol implementation shouldn't need to know on

 *                which hardware it is running

 *              - user-level programs like the AX.25 utilities shouldn't

 *                need to know about the hardware.

 *              - IP over ethernet encapsulated AX.25 was impossible

 *              - rxecho.c did not work

 *              - to have room for extensions

 *              - it just deserves to "live" as an own driver

 *

 *      This driver can use any ethernet destination address, and can be

 *      limited to accept frames from one dedicated ethernet card only.

 *

 *      Note that the driver sets up the BPQ devices automagically on

 *      startup or (if started before the "insmod" of an ethernet device)

 *      on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing

 *      the ethernet device (in fact: as soon as another ethernet or bpq

 *      device gets "ifconfig"ured).

 *

 *      I have heard that several people are thinking of experiments

 *      with highspeed packet radio using existing ethernet cards.

 *      Well, this driver is prepared for this purpose, just add

 *      your tx key control and a txdelay / tailtime algorithm,

 *      probably some buffering, and /voila/...

 *

 *      History

 *      BPQ   001       Joerg(DL1BKE)           Extracted BPQ code from AX.25

 *                                              protocol stack and added my own

 *                                              yet existing patches

 *      BPQ   002       Joerg(DL1BKE)           Scan network device list on

 *                                              startup.

 *      BPQ   003       Joerg(DL1BKE)           Ethernet destination address

 *                                              and accepted source address

 *                                              can be configured by an ioctl()

 *                                              call.

 */

#include <linux/config.h>

#include <linux/errno.h>

#include <linux/types.h>

#include <linux/socket.h>

#include <linux/in.h>

#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/net.h>

#include <net/ax25.h>

#include <linux/inet.h>

#include <linux/netdevice.h>

#include <linux/if_arp.h>

#include <linux/skbuff.h>

#include <net/sock.h>

#include <asm/segment.h>

#include <asm/system.h>

#include <linux/mm.h>

#include <linux/interrupt.h>

#include <linux/notifier.h>

#include <linux/proc_fs.h>

#include <linux/stat.h>

#include <linux/firewall.h>

#include <linux/module.h>

#include <linux/net_alias.h>

#include <net/ip.h>

#include <net/arp.h>

#include <linux/bpqether.h>

static unsigned char ax25_bcast[AX25_ADDR_LEN] =

        {'Q' << 1, 'S' << 1, 'T' << 1, ' ' << 1, ' ' << 1, ' ' << 1, '0' << 1};

static unsigned char ax25_defaddr[AX25_ADDR_LEN] =

        {'L' << 1, 'I' << 1, 'N' << 1, 'U' << 1, 'X' << 1, ' ' << 1, '1' << 1};

static char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};

static char bpq_eth_addr[6];

static int bpq_rcv(struct sk_buff *, struct device *, struct packet_type *);

static int bpq_device_event(struct notifier_block *, unsigned long, void *);

static char *bpq_print_ethaddr(unsigned char *);

static struct packet_type bpq_packet_type = {

        0,               /* ntohs(ETH_P_BPQ),*/

        0,               /* copy */

        bpq_rcv,

        NULL,

        NULL,

};

static struct notifier_block bpq_dev_notifier = {

        bpq_device_event,

};

#define MAXBPQDEV 100

static struct bpqdev {

        struct bpqdev *next;

        char   ethname[14];             /* ether device name */

        struct device *ethdev;          /* link to ethernet device */

        struct device axdev;            /* bpq device (bpq#) */

        struct enet_statistics stats;   /* some statistics */

        char   dest_addr[6];            /* ether destination address */

        char   acpt_addr[6];            /* accept ether frames from this address only */

} *bpq_devices = NULL;

/* ------------------------------------------------------------------------ */

/*

 *      Get the ethernet device for a BPQ device

 */

static __inline__ struct device *bpq_get_ether_dev(struct device *dev)

{

        struct bpqdev *bpq;

        bpq = (struct bpqdev *)dev->priv;

        return (bpq != NULL) ? bpq->ethdev : NULL;

}

/*

 *      Get the BPQ device for the ethernet device

 */

static __inline__ struct device *bpq_get_ax25_dev(struct device *dev)

{

        struct bpqdev *bpq;

        for (bpq = bpq_devices; bpq != NULL; bpq = bpq->next)

                if (bpq->ethdev == dev)

                        return &bpq->axdev;

        return NULL;

}

static __inline__ int dev_is_ethdev(struct device *dev)

{

        return (

                        dev->type == ARPHRD_ETHER

                        && strncmp(dev->name, "dummy", 5)

#ifdef CONFIG_NET_ALIAS

                        && !net_alias_is(dev)

#endif

        );

}

/*

 *      Sanity check: remove all devices that ceased to exists and

 *      return '1' if the given BPQ device was affected.

 */

static int bpq_check_devices(struct device *dev)

{

        struct bpqdev *bpq, *bpq_prev;

        int result = 0;

        unsigned long flags;

        save_flags(flags);

        cli();

        bpq_prev = NULL;

        for (bpq = bpq_devices; bpq != NULL; bpq = bpq->next) {

                if (!dev_get(bpq->ethname)) {

                        if (bpq_prev)

                                bpq_prev->next = bpq->next;

                        else

                                bpq_devices = bpq->next;

                        if (&bpq->axdev == dev)

                                result = 1;

                        unregister_netdev(&bpq->axdev);

                        kfree(bpq);

                }

                bpq_prev = bpq;

        }

        restore_flags(flags);

        return result;

}

/* ------------------------------------------------------------------------ */

/*

 *      Receive an AX.25 frame via an ethernet interface.

 */

static int bpq_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *ptype)

{

        int len;

        char * ptr;

        struct ethhdr *eth = (struct ethhdr *)skb->mac.raw;

        struct bpqdev *bpq;

        skb->sk = NULL;         /* Initially we don't know who it's for */

        dev = bpq_get_ax25_dev(dev);

        if (dev == NULL || dev->start == 0) {

                kfree_skb(skb, FREE_READ);

                return 0;

        }

        /*

         * if we want to accept frames from just one ethernet device

         * we check the source address of the sender.

         */

        bpq = (struct bpqdev *)dev->priv;

        if (!(bpq->acpt_addr[0] & 0x01) && memcmp(eth->h_source, bpq->acpt_addr, ETH_ALEN)) {

                printk(KERN_DEBUG "bpqether: wrong dest %s\n", bpq_print_ethaddr(eth->h_source));

                kfree_skb(skb, FREE_READ);

                return 0;

        }

        ((struct bpqdev *)dev->priv)->stats.rx_packets++;

        len = skb->data[0] + skb->data[1] * 256 - 5;

        skb_pull(skb, 2);       /* Remove the length bytes */

        skb_trim(skb, len);     /* Set the length of the data */

        ptr = skb_push(skb, 1);

        *ptr = 0;

        skb->dev = dev;

        skb->protocol = htons(ETH_P_AX25);

        skb->mac.raw = skb->data;

        skb->pkt_type = PACKET_HOST;

        netif_rx(skb);

        return 0;

}

/*

 *      Send an AX.25 frame via an ethernet interface

 */

static int bpq_xmit(struct sk_buff *skb, struct device *dev)

{

        unsigned char *ptr;

        struct bpqdev *bpq;

        int size;

        /*

         * Just to be *really* sure not to send anything if the interface

         * is down, the ethernet device may have gone.

         */

        if (!dev->start) {

                bpq_check_devices(dev);

                dev_kfree_skb(skb, FREE_WRITE);

                return -ENODEV;

        }

        skb_pull(skb, 1);

        size = skb->len;

        /*

         * The AX.25 code leaves enough room for the ethernet header, but

         * sendto() does not.

         */

        if (skb_headroom(skb) < AX25_BPQ_HEADER_LEN) {  /* Ough! */

                struct sk_buff *newskb = alloc_skb(skb->len + AX25_BPQ_HEADER_LEN, GFP_ATOMIC);

                if (newskb == NULL) {                   /* Argh! */

                        printk(KERN_WARNING "bpq_xmit: not enough space to add BPQ Ether header\n");

                        dev_kfree_skb(skb, FREE_WRITE);

                        return -ENOMEM;

                }

                newskb->free = 1;

                newskb->arp  = 1;

                if (skb->sk != NULL)

                        atomic_add(newskb->truesize, &skb->sk->wmem_alloc);

                newskb->sk   = skb->sk;

                skb_reserve(newskb, AX25_BPQ_HEADER_LEN);

                memcpy(skb_put(newskb, size), skb->data, size);

                dev_kfree_skb(skb, FREE_WRITE);

                skb = newskb;

        }

        skb->protocol = htons(ETH_P_AX25);

        ptr = skb_push(skb, 2);

        *ptr++ = (size + 5) % 256;

        *ptr++ = (size + 5) / 256;

        bpq = (struct bpqdev *)dev->priv;

        bpq->stats.tx_packets++;

        if ((dev = bpq_get_ether_dev(dev)) == NULL) {

                bpq->stats.tx_dropped++;

                dev_kfree_skb(skb, FREE_WRITE);

                return -ENODEV;

        }

        skb->dev = dev;

        dev->hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0);

        dev_queue_xmit(skb, dev, SOPRI_NORMAL);

        return 0;

}

/*

 *      Statistics

 */

static struct enet_statistics *bpq_get_stats(struct device *dev)

{

        struct bpqdev *bpq;

        bpq = (struct bpqdev *)dev->priv;

        return &bpq->stats;

}

/*

 *      Set AX.25 callsign

 */

static int bpq_set_mac_address(struct device *dev, void *addr)

{

    struct sockaddr *sa = (struct sockaddr *)addr;

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

    return 0;

}

/*      Ioctl commands

 *

 *              SIOCSBPQETHOPT          reserved for enhancements

 *              SIOCSBPQETHADDR         set the destination and accepted

 *                                      source ethernet address (broadcast

 *                                      or multicast: accept all)

 */

static int bpq_ioctl(struct device *dev, struct ifreq *ifr, int cmd)

{

        int err;

        struct bpq_ethaddr *ethaddr = (struct bpq_ethaddr *)ifr->ifr_data;

        struct bpqdev *bpq = dev->priv;

        struct bpq_req req;

        if (!suser())

                return -EPERM;

        if (bpq == NULL)                /* woops! */

                return -ENODEV;

        switch (cmd) {

                case SIOCSBPQETHOPT:

                        if ((err = verify_area(VERIFY_WRITE, ifr->ifr_data, sizeof(struct bpq_req))) != 0)

                                return err;

                        memcpy_fromfs(&req, ifr->ifr_data, sizeof(struct bpq_req));

                        switch (req.cmd) {

                                case SIOCGBPQETHPARAM:

                                case SIOCSBPQETHPARAM:

                                default:

                                        return -EINVAL;

                        }

                        break;

                case SIOCSBPQETHADDR:

                        if ((err = verify_area(VERIFY_READ, ethaddr, sizeof(struct bpq_ethaddr))) != 0)

                                return err;

                        memcpy_fromfs(bpq->dest_addr, ethaddr->destination, ETH_ALEN);

                        memcpy_fromfs(bpq->acpt_addr, ethaddr->accept, ETH_ALEN);

                        break;

                default:

                        return -EINVAL;

        }

        return 0;

}

/*

 * open/close a device

 */

static int bpq_open(struct device *dev)

{

        if (bpq_check_devices(dev))

                return -ENODEV;         /* oops, it's gone */

        dev->tbusy = 0;

        dev->start = 1;

        MOD_INC_USE_COUNT;

        return 0;

}

static int bpq_close(struct device *dev)

{

        dev->tbusy = 1;

        dev->start = 0;

        MOD_DEC_USE_COUNT;

        return 0;

}

/*

 * currently unused

 */

static int bpq_dev_init(struct device *dev)

{

        return 0;

}

/* ------------------------------------------------------------------------ */

/*

 *      Proc filesystem

 */

static char * bpq_print_ethaddr(unsigned char *e)

{

        static char buf[18];

        sprintf(buf, "%2.2X:%2.2X:%2.2X:%2.2X:%2.2X:%2.2X",

                e[0], e[1], e[2], e[3], e[4], e[5]);

        return buf;

}

int bpq_get_info(char *buffer, char **start, off_t offset, int length, int dummy)

{

        struct bpqdev *bpqdev;

        int len     = 0;

        off_t pos   = 0;

        off_t begin = 0;

        cli();

        len += sprintf(buffer, "dev   ether      destination        accept from\n");

        for (bpqdev = bpq_devices; bpqdev != NULL; bpqdev = bpqdev->next) {

                len += sprintf(buffer + len, "%-5s %-10s %s  ",

                        bpqdev->axdev.name, bpqdev->ethname,

                        bpq_print_ethaddr(bpqdev->dest_addr));

                len += sprintf(buffer + len, "%s\n",

                        (bpqdev->acpt_addr[0] & 0x01) ? "*" : bpq_print_ethaddr(bpqdev->acpt_addr));

                pos = begin + len;

                if (pos < offset) {

                        len   = 0;

                        begin = pos;

                }

                if (pos > offset + length)

                        break;

        }

        sti();

        *start = buffer + (offset - begin);

        len   -= (offset - begin);

        if (len > length) len = length;

        return len;

}

/* ------------------------------------------------------------------------ */

/*

 *      Setup a new device.

 */

static int bpq_new_device(struct device *dev)

{

        int k;

        unsigned char *buf;

        struct bpqdev *bpq, *bpq2;

        if ((bpq = (struct bpqdev *)kmalloc(sizeof(struct bpqdev), GFP_KERNEL)) == NULL)

                return -ENOMEM;

        memset(bpq, 0, sizeof(struct bpqdev));

        bpq->ethdev = dev;

        bpq->ethname[sizeof(bpq->ethname)-1] = '\0';

        strncpy(bpq->ethname, dev->name, sizeof(bpq->ethname)-1);

        memcpy(bpq->dest_addr, bcast_addr, sizeof(bpq_eth_addr));

        memcpy(bpq->acpt_addr, bcast_addr, sizeof(bpq_eth_addr));

        dev = &bpq->axdev;

        buf = (unsigned char *)kmalloc(14, GFP_KERNEL);

        for (k = 0; k < MAXBPQDEV; k++) {

                struct device *odev;

                sprintf(buf, "bpq%d", k);

                if ((odev = dev_get(buf)) == NULL || bpq_check_devices(odev))

                        break;

        }

        if (k == MAXBPQDEV) {

                kfree(bpq);

                return -ENODEV;

        }

        dev->priv = (void *)bpq;        /* pointer back */

        dev->name = buf;

        dev->init = bpq_dev_init;

        if (register_netdev(dev) != 0) {

                kfree(bpq);

                return -EIO;

        }

        for (k=0; k < DEV_NUMBUFFS; k++)

                skb_queue_head_init(&dev->buffs[k]);

        dev->hard_start_xmit = bpq_xmit;

        dev->open            = bpq_open;

        dev->stop            = bpq_close;

        dev->set_mac_address = bpq_set_mac_address;

        dev->get_stats       = bpq_get_stats;

        dev->do_ioctl        = bpq_ioctl;

        memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);

        memcpy(dev->dev_addr,  ax25_defaddr, AX25_ADDR_LEN);

        /* preset with reasonable values */

        dev->flags      = 0;

        dev->family     = AF_INET;

#ifdef CONFIG_INET

        dev->pa_addr    = in_aton("192.168.0.1");

        dev->pa_brdaddr = in_aton("192.168.0.255");

        dev->pa_mask    = in_aton("255.255.255.0");

        dev->pa_alen    = 4;

#endif

#if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)

        dev->hard_header     = ax25_encapsulate;

        dev->rebuild_header  = ax25_rebuild_header;

#endif

        dev->type            = ARPHRD_AX25;

        dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;

        dev->mtu             = AX25_DEF_PACLEN;

        dev->addr_len        = AX25_ADDR_LEN;

        cli();

        if (bpq_devices == NULL) {

                bpq_devices = bpq;

        } else {

                for (bpq2 = bpq_devices; bpq2->next != NULL; bpq2 = bpq2->next);

                bpq2->next = bpq;

        }

        sti();

        return 0;

}

/*

 *      Handle device status changes.

 */

static int bpq_device_event(struct notifier_block *this,unsigned long event, void *ptr)

{

        struct device *dev = (struct device *)ptr;

        if (!dev_is_ethdev(dev))

                return NOTIFY_DONE;

        bpq_check_devices(NULL);

        switch (event) {

                case NETDEV_UP:         /* new ethernet device -> new BPQ interface */

                        if (bpq_get_ax25_dev(dev) == NULL)

                                bpq_new_device(dev);

                        break;

                case NETDEV_DOWN:       /* ethernet device closed -> close BPQ interface */

                        if ((dev = bpq_get_ax25_dev(dev)) != NULL)

                                dev_close(dev);

                        break;

                default:

                        break;

        }

        return NOTIFY_DONE;

}

/* ------------------------------------------------------------------------ */

/*

 * Initialize driver. To be called from af_ax25 if not compiled as a

 * module

 */

int bpq_init(void)

{

        struct device *dev;

        bpq_packet_type.type  = htons(ETH_P_BPQ);

        dev_add_pack(&bpq_packet_type);

        register_netdevice_notifier(&bpq_dev_notifier);

        printk(KERN_INFO "AX.25 ethernet driver version 0.01\n");

#ifdef CONFIG_PROC_FS

        proc_net_register(&(struct proc_dir_entry) {

                PROC_NET_AX25_BPQETHER, 8, "bpqether",

                S_IFREG | S_IRUGO, 1, 0, 0,

                0, &proc_net_inode_operations,

                bpq_get_info

        });

#endif

        for (dev = dev_base; dev != NULL; dev = dev->next) {

                if (dev_is_ethdev(dev))

                        bpq_new_device(dev);

        }

        return 0;

}

#ifdef MODULE

int init_module(void)

{

        register_symtab(NULL);

        return bpq_init();

}

void cleanup_module(void)

{

        struct bpqdev *bpq;

        dev_remove_pack(&bpq_packet_type);

        unregister_netdevice_notifier(&bpq_dev_notifier);

#ifdef CONFIG_PROC_FS

        proc_net_unregister(PROC_NET_AX25_BPQETHER);

#endif

        for (bpq = bpq_devices; bpq != NULL; bpq = bpq->next)

                unregister_netdev(&bpq->axdev);

}

#endif