mkiss.c

linux-2.4.29操作系统的源码

	if (type != htons(ETH_P_AX25))
		return ax25_encapsulate(skb, dev, type, daddr, saddr, len);
#endif
	return 0;
}


static int ax_rebuild_header(struct sk_buff *skb)
{
#ifdef CONFIG_INET
	return ax25_rebuild_header(skb);
#else
	return 0;
#endif
}

#endif	/* CONFIG_{AX25,AX25_MODULE} */

/* Open the low-level part of the AX25 channel. Easy! */
static int ax_open(struct net_device *dev)
{
	struct ax_disp *ax = (struct ax_disp *) dev->priv;
	unsigned long len;

	if (ax->tty == NULL)
		return -ENODEV;

	/*
	 * Allocate the frame buffers:
	 *
	 * rbuff	Receive buffer.
	 * xbuff	Transmit buffer.
	 */
	len = dev->mtu * 2;

	/*
	 * allow for arrival of larger UDP packets, even if we say not to
	 * also fixes a bug in which SunOS sends 512-byte packets even with
	 * an MSS of 128
	 */
	if (len < 576 * 2)
		len = 576 * 2;

	if ((ax->rbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
		goto norbuff;

	if ((ax->xbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
		goto noxbuff;

	ax->mtu	     = dev->mtu + 73;
	ax->buffsize = len;
	ax->rcount   = 0;
	ax->xleft    = 0;

	ax->flags   &= (1 << AXF_INUSE);      /* Clear ESCAPE & ERROR flags */

	netif_start_queue(dev);
	return 0;

noxbuff:
	kfree(ax->rbuff);

norbuff:
	return -ENOMEM;
}


/* Close the low-level part of the AX25 channel. Easy! */
static int ax_close(struct net_device *dev)
{
	struct ax_disp *ax = (struct ax_disp *) dev->priv;

	if (ax->tty == NULL)
		return -EBUSY;

	ax->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);

	netif_stop_queue(dev);

	return 0;
}

static int ax25_receive_room(struct tty_struct *tty)
{
	return 65536;  /* We can handle an infinite amount of data. :-) */
}

/*
 * Handle the 'receiver data ready' interrupt.
 * This function is called by the 'tty_io' module in the kernel when
 * a block of data has been received, which can now be decapsulated
 * and sent on to the AX.25 layer for further processing.
 */
static void ax25_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
{
	struct ax_disp *ax = (struct ax_disp *) tty->disc_data;

	if (ax == NULL || ax->magic != AX25_MAGIC || !netif_running(ax->dev))
		return;

	/*
	 * Argh! mtu change time! - costs us the packet part received
	 * at the change
	 */
	if (ax->mtu != ax->dev->mtu + 73)
		ax_changedmtu(ax);

	/* Read the characters out of the buffer */
	while (count--) {
		if (fp != NULL && *fp++) {
			if (!test_and_set_bit(AXF_ERROR, &ax->flags))
				ax->rx_errors++;
			cp++;
			continue;
		}

		kiss_unesc(ax, *cp++);
	}
}

static int ax25_open(struct tty_struct *tty)
{
	struct ax_disp *ax = (struct ax_disp *) tty->disc_data;
	struct ax_disp *tmp_ax;
	struct mkiss_channel *mkiss;
	int err, cnt;

	/* First make sure we're not already connected. */
	if (ax && ax->magic == AX25_MAGIC)
		return -EEXIST;

	/* OK.  Find a free AX25 channel to use. */
	if ((ax = ax_alloc()) == NULL)
		return -ENFILE;

	ax->tty = tty;
	tty->disc_data = ax;

	ax->mkiss = NULL;
	tmp_ax    = NULL;

	if (tty->driver.flush_buffer)
		tty->driver.flush_buffer(tty);
	tty_ldisc_flush(tty);

	/* Restore default settings */
	ax->dev->type = ARPHRD_AX25;

	/* Perform the low-level AX25 initialization. */
	if ((err = ax_open(ax->dev)))
		return err;

	mkiss = ax->tty->driver_data;

	if (mkiss->magic  == MKISS_DRIVER_MAGIC) {
		for (cnt = 1; cnt < ax25_maxdev; cnt++) {
			if (ax25_ctrls[cnt]) {
				if (netif_running(&ax25_ctrls[cnt]->dev)) {
					if (ax == &ax25_ctrls[cnt]->ctrl) {
						cnt--;
						tmp_ax = &ax25_ctrls[cnt]->ctrl;
						break;
					}
				}
			}
		}
	}

	if (tmp_ax != NULL) {
		ax->mkiss     = tmp_ax;
		tmp_ax->mkiss = ax;
	}

	MOD_INC_USE_COUNT;

	/* Done.  We have linked the TTY line to a channel. */
	return ax->dev->base_addr;
}

static void ax25_close(struct tty_struct *tty)
{
	struct ax_disp *ax = (struct ax_disp *) tty->disc_data;

	/* First make sure we're connected. */
	if (ax == NULL || ax->magic != AX25_MAGIC)
		return;

	unregister_netdev(ax->dev);

	tty->disc_data = 0;
	ax->tty        = NULL;

	ax_free(ax);
	MOD_DEC_USE_COUNT;
}


static struct net_device_stats *ax_get_stats(struct net_device *dev)
{
	static struct net_device_stats stats;
	struct ax_disp *ax = (struct ax_disp *) dev->priv;

	memset(&stats, 0, sizeof(struct net_device_stats));

	stats.rx_packets     = ax->rx_packets;
	stats.tx_packets     = ax->tx_packets;
	stats.rx_bytes	     = ax->rx_bytes;
	stats.tx_bytes       = ax->tx_bytes;
	stats.rx_dropped     = ax->rx_dropped;
	stats.tx_dropped     = ax->tx_dropped;
	stats.tx_errors      = ax->tx_errors;
	stats.rx_errors      = ax->rx_errors;
	stats.rx_over_errors = ax->rx_over_errors;

	return &stats;
}


/************************************************************************
 *			   STANDARD ENCAPSULATION	        	 *
 ************************************************************************/

static int kiss_esc(unsigned char *s, unsigned char *d, int len)
{
	unsigned char *ptr = d;
	unsigned char c;

	/*
	 * Send an initial END character to flush out any
	 * data that may have accumulated in the receiver
	 * due to line noise.
	 */

	*ptr++ = END;

	while (len-- > 0) {
		switch (c = *s++) {
			case END:
				*ptr++ = ESC;
				*ptr++ = ESC_END;
				break;
			case ESC:
				*ptr++ = ESC;
				*ptr++ = ESC_ESC;
				break;
			default:
				*ptr++ = c;
				break;
		}
	}

	*ptr++ = END;

	return ptr - d;
}

/*
 * MW:
 * OK its ugly, but tell me a better solution without copying the
 * packet to a temporary buffer :-)
 */
static int kiss_esc_crc(unsigned char *s, unsigned char *d, unsigned short crc, int len)
{
	unsigned char *ptr = d;
	unsigned char c=0;

	*ptr++ = END;
	while (len > 0) {
		if (len > 2) 
			c = *s++;
		else if (len > 1)
			c = crc >> 8;
		else if (len > 0)
			c = crc & 0xff;

		len--;

		switch (c) {
                        case END:
                                *ptr++ = ESC;
                                *ptr++ = ESC_END;
                                break;
                        case ESC:
                                *ptr++ = ESC;
                                *ptr++ = ESC_ESC;
                                break;
                        default:
                                *ptr++ = c;
                                break;
		}
	}
	*ptr++ = END;
	return ptr - d;		
}

static void kiss_unesc(struct ax_disp *ax, unsigned char s)
{
	switch (s) {
		case END:
			/* drop keeptest bit = VSV */
			if (test_bit(AXF_KEEPTEST, &ax->flags))
				clear_bit(AXF_KEEPTEST, &ax->flags);

			if (!test_and_clear_bit(AXF_ERROR, &ax->flags) && (ax->rcount > 2))
				ax_bump(ax);

			clear_bit(AXF_ESCAPE, &ax->flags);
			ax->rcount = 0;
			return;

		case ESC:
			set_bit(AXF_ESCAPE, &ax->flags);
			return;
		case ESC_ESC:
			if (test_and_clear_bit(AXF_ESCAPE, &ax->flags))
				s = ESC;
			break;
		case ESC_END:
			if (test_and_clear_bit(AXF_ESCAPE, &ax->flags))
				s = END;
			break;
	}

	if (!test_bit(AXF_ERROR, &ax->flags)) {
		if (ax->rcount < ax->buffsize) {
			ax->rbuff[ax->rcount++] = s;
			return;
		}

		ax->rx_over_errors++;
		set_bit(AXF_ERROR, &ax->flags);
	}
}


static int ax_set_mac_address(struct net_device *dev, void *addr)
{
	if (copy_from_user(dev->dev_addr, addr, AX25_ADDR_LEN))
		return -EFAULT;
	return 0;
}

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

	memcpy(dev->dev_addr, sa->sa_data, AX25_ADDR_LEN);

	return 0;
}


/* Perform I/O control on an active ax25 channel. */
static int ax25_disp_ioctl(struct tty_struct *tty, void *file, int cmd, void *arg)
{
	struct ax_disp *ax = (struct ax_disp *) tty->disc_data;
	unsigned int tmp;

	/* First make sure we're connected. */
	if (ax == NULL || ax->magic != AX25_MAGIC)
		return -EINVAL;

	switch (cmd) {
	 	case SIOCGIFNAME:
			if (copy_to_user(arg, ax->dev->name, strlen(ax->dev->name) + 1))
				return -EFAULT;
			return 0;

		case SIOCGIFENCAP:
			return put_user(4, (int *)arg);

		case SIOCSIFENCAP:
			if (get_user(tmp, (int *)arg))
				return -EFAULT;
			ax->mode = tmp;
			ax->dev->addr_len        = AX25_ADDR_LEN;	  /* sizeof an AX.25 addr */
			ax->dev->hard_header_len = AX25_KISS_HEADER_LEN + AX25_MAX_HEADER_LEN + 3;
			ax->dev->type            = ARPHRD_AX25;
			return 0;

		 case SIOCSIFHWADDR:
			return ax_set_mac_address(ax->dev, arg);

		default:
			return -ENOIOCTLCMD;
	}
}

static int ax_open_dev(struct net_device *dev)
{
	struct ax_disp *ax = (struct ax_disp *) dev->priv;

	if (ax->tty == NULL)
		return -ENODEV;

	return 0;
}


/* Initialize the driver.  Called by network startup. */
static int ax25_init(struct net_device *dev)
{
	struct ax_disp *ax = (struct ax_disp *) dev->priv;

	static char ax25_bcast[AX25_ADDR_LEN] =
		{'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};
	static char ax25_test[AX25_ADDR_LEN] =
		{'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};

	if (ax == NULL)		/* Allocation failed ?? */
		return -ENODEV;

	/* Set up the "AX25 Control Block". (And clear statistics) */
	memset(ax, 0, sizeof (struct ax_disp));
	ax->magic  = AX25_MAGIC;
	ax->dev	   = dev;

	/* Finish setting up the DEVICE info. */
	dev->mtu             = AX_MTU;
	dev->hard_start_xmit = ax_xmit;
	dev->open            = ax_open_dev;
	dev->stop            = ax_close;
	dev->get_stats	     = ax_get_stats;
	dev->set_mac_address = ax_set_dev_mac_address;
	dev->hard_header_len = 0;
	dev->addr_len        = 0;
	dev->type            = ARPHRD_AX25;
	dev->tx_queue_len    = 10;
	dev->hard_header     = ax_header;
	dev->rebuild_header  = ax_rebuild_header;

	memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);
	memcpy(dev->dev_addr,  ax25_test,  AX25_ADDR_LEN);

	/* New-style flags. */
	dev->flags      = IFF_BROADCAST | IFF_MULTICAST;

	return 0;
}


/* ******************************************************************** */
/* *			Init MKISS driver			      * */
/* ******************************************************************** */

static int __init mkiss_init_driver(void)
{
	int status;

	printk(banner);

	if (ax25_maxdev < 4)
	  ax25_maxdev = 4; /* Sanity */

	if ((ax25_ctrls = kmalloc(sizeof(void *) * ax25_maxdev, GFP_KERNEL)) == NULL) {
		printk(KERN_ERR "mkiss: Can't allocate ax25_ctrls[] array!\n");
		return -ENOMEM;
	}

	/* Clear the pointer array, we allocate devices when we need them */
	memset(ax25_ctrls, 0, sizeof(void*) * ax25_maxdev); /* Pointers */

	/* Fill in our line protocol discipline, and register it */
	ax_ldisc.magic		= TTY_LDISC_MAGIC;
	ax_ldisc.name		= "mkiss";
	ax_ldisc.open		= ax25_open;
	ax_ldisc.close		= ax25_close;
	ax_ldisc.ioctl		= (int (*)(struct tty_struct *, struct file *,
					unsigned int, unsigned long))ax25_disp_ioctl;
	ax_ldisc.receive_buf	= ax25_receive_buf;
	ax_ldisc.receive_room	= ax25_receive_room;
	ax_ldisc.write_wakeup	= ax25_write_wakeup;

	if ((status = tty_register_ldisc(N_AX25, &ax_ldisc)) != 0) {
		printk(KERN_ERR "mkiss: can't register line discipline (err = %d)\n", status);
		kfree(ax25_ctrls);
	}
	return status;
}

static void __exit mkiss_exit_driver(void)
{
	int i;

	for (i = 0; i < ax25_maxdev; i++) {
		if (ax25_ctrls[i]) {
			/*
			* VSV = if dev->start==0, then device
			* unregistered while close proc.
			*/
			if (netif_running(&ax25_ctrls[i]->dev))
				unregister_netdev(&ax25_ctrls[i]->dev);
			kfree(ax25_ctrls[i]);
		}
	}

	kfree(ax25_ctrls);
	ax25_ctrls = NULL;

	if ((i = tty_register_ldisc(N_AX25, NULL)))
		printk(KERN_ERR "mkiss: can't unregister line discipline (err = %d)\n", i);
}

MODULE_AUTHOR("Hans Albas PE1AYX <[e-mail]>");
MODULE_DESCRIPTION("KISS driver for AX.25 over TTYs");
MODULE_PARM(ax25_maxdev, "i");
MODULE_PARM_DESC(ax25_maxdev, "number of MKISS devices");
MODULE_LICENSE("GPL");

module_init(mkiss_init_driver);
module_exit(mkiss_exit_driver);