slip.c

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		clear_bit(SLF_ESCAPE, &sl->flags);
		sl->rcount = 0;
		return;

	 case ESC:
		set_bit(SLF_ESCAPE, &sl->flags);
		return;
	 case ESC_ESC:
		if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))  {
			s = ESC;
		}
		break;
	 case ESC_END:
		if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))  {
			s = END;
		}
		break;
	}
	if (!test_bit(SLF_ERROR, &sl->flags))  {
		if (sl->rcount < sl->buffsize)  {
			sl->rbuff[sl->rcount++] = s;
			return;
		}
		sl->rx_over_errors++;
		set_bit(SLF_ERROR, &sl->flags);
	}
}


#ifdef CONFIG_SLIP_MODE_SLIP6
/************************************************************************
 *			 6 BIT SLIP ENCAPSULATION			*
 ************************************************************************/

int
slip_esc6(unsigned char *s, unsigned char *d, int len)
{
	unsigned char *ptr = d;
	unsigned char c;
	int i;
	unsigned short v = 0;
	short bits = 0;

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

	*ptr++ = 0x70;

	/*
	 * Encode the packet into printable ascii characters
	 */

	for (i = 0; i < len; ++i) {
		v = (v << 8) | s[i];
		bits += 8;
		while (bits >= 6) {
			bits -= 6;
			c = 0x30 + ((v >> bits) & 0x3F);
			*ptr++ = c;
		}
	}
	if (bits) {
		c = 0x30 + ((v << (6 - bits)) & 0x3F);
		*ptr++ = c;
	}
	*ptr++ = 0x70;
	return ptr - d;
}

void
slip_unesc6(struct slip *sl, unsigned char s)
{
	unsigned char c;

	if (s == 0x70) {
#ifdef CONFIG_SLIP_SMART
		/* drop keeptest bit = VSV */
		if (test_bit(SLF_KEEPTEST, &sl->flags))
			clear_bit(SLF_KEEPTEST, &sl->flags);
#endif

		if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && (sl->rcount > 2))  {
			sl_bump(sl);
		}
		sl->rcount = 0;
		sl->xbits = 0;
		sl->xdata = 0;
 	} else if (s >= 0x30 && s < 0x70) {
		sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
		sl->xbits += 6;
		if (sl->xbits >= 8) {
			sl->xbits -= 8;
			c = (unsigned char)(sl->xdata >> sl->xbits);
			if (!test_bit(SLF_ERROR, &sl->flags))  {
				if (sl->rcount < sl->buffsize)  {
					sl->rbuff[sl->rcount++] = c;
					return;
				}
				sl->rx_over_errors++;
				set_bit(SLF_ERROR, &sl->flags);
			}
		}
 	}
}
#endif /* CONFIG_SLIP_MODE_SLIP6 */

/* Perform I/O control on an active SLIP channel. */
static int
slip_ioctl(struct tty_struct *tty, void *file, int cmd, void *arg)
{
	struct slip *sl = (struct slip *) tty->disc_data;
	unsigned int tmp;

	/* First make sure we're connected. */
	if (!sl || sl->magic != SLIP_MAGIC) {
		return -EINVAL;
	}

	switch(cmd) {
	 case SIOCGIFNAME:
		/* Please, do not put this line under copy_to_user,
		   it breaks my old poor gcc on alpha --ANK
		 */
		tmp = strlen(sl->dev->name) + 1;
		if (copy_to_user(arg, sl->dev->name, tmp))
			return -EFAULT;
		return 0;

	case SIOCGIFENCAP:
		if (put_user(sl->mode, (int *)arg))
			return -EFAULT;
		return 0;

	case SIOCSIFENCAP:
		if (get_user(tmp,(int *)arg))
			return -EFAULT;
#ifndef SL_INCLUDE_CSLIP
		if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))  {
			return -EINVAL;
		}
#else
		if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
		    (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))  {
			/* return -EINVAL; */
			tmp &= ~SL_MODE_ADAPTIVE;
		}
#endif
#ifndef CONFIG_SLIP_MODE_SLIP6
		if (tmp & SL_MODE_SLIP6)  {
			return -EINVAL;
		}
#endif
		sl->mode = tmp;
		sl->dev->type = ARPHRD_SLIP+sl->mode;
		return 0;

	 case SIOCSIFHWADDR:
		return -EINVAL;

#ifdef CONFIG_SLIP_SMART
	/* VSV changes start here */
        case SIOCSKEEPALIVE:
		if (get_user(tmp,(int *)arg))
			return -EFAULT;
                if (tmp > 255) /* max for unchar */
			return -EINVAL;

		spin_lock_bh(&sl->lock);
		if (!sl->tty) {
			spin_unlock_bh(&sl->lock);
			return -ENODEV;
		}
		if ((sl->keepalive = (unchar) tmp) != 0) {
			mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
			set_bit(SLF_KEEPTEST, &sl->flags);
                } else {
                        del_timer (&sl->keepalive_timer);
		}
		spin_unlock_bh(&sl->lock);
		return 0;

        case SIOCGKEEPALIVE:
		if (put_user(sl->keepalive, (int *)arg))
			return -EFAULT;
		return 0;

        case SIOCSOUTFILL:
		if (get_user(tmp,(int *)arg))
			return -EFAULT;
                if (tmp > 255) /* max for unchar */
			return -EINVAL;
		spin_lock_bh(&sl->lock);
		if (!sl->tty) {
			spin_unlock_bh(&sl->lock);
			return -ENODEV;
		}
                if ((sl->outfill = (unchar) tmp) != 0){
			mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
			set_bit(SLF_OUTWAIT, &sl->flags);
		} else {
                        del_timer (&sl->outfill_timer);
		}
		spin_unlock_bh(&sl->lock);
                return 0;

        case SIOCGOUTFILL:
		if (put_user(sl->outfill, (int *)arg))
			return -EFAULT;
		return 0;
	/* VSV changes end */
#endif

	/* Allow stty to read, but not set, the serial port */
	case TCGETS:
	case TCGETA:
		return n_tty_ioctl(tty, (struct file *) file, cmd, (unsigned long) arg);

	default:
		return -ENOIOCTLCMD;
	}
}

/* VSV changes start here */
#ifdef CONFIG_SLIP_SMART
/* function do_ioctl called from net/core/dev.c
   to allow get/set outfill/keepalive parameter
   by ifconfig                                 */

static int sl_ioctl(struct net_device *dev,struct ifreq *rq,int cmd)
{
	struct slip *sl = (struct slip*)(dev->priv);

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

	spin_lock_bh(&sl->lock);

	if (!sl->tty) {
		spin_unlock_bh(&sl->lock);
		return -ENODEV;
	}

	switch(cmd){
        case SIOCSKEEPALIVE:
		/* max for unchar */
                if (((unsigned int)((unsigned long)rq->ifr_data)) > 255) {
			spin_unlock_bh(&sl->lock);
			return -EINVAL;
		}
		sl->keepalive = (unchar) ((unsigned long)rq->ifr_data);
		if (sl->keepalive != 0) {
			sl->keepalive_timer.expires=jiffies+sl->keepalive*HZ;
			mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
			set_bit(SLF_KEEPTEST, &sl->flags);
                } else {
                        del_timer(&sl->keepalive_timer);
		}
		break;

        case SIOCGKEEPALIVE:
		rq->ifr_data=(caddr_t)((unsigned long)sl->keepalive);
		break;

        case SIOCSOUTFILL:
                if (((unsigned)((unsigned long)rq->ifr_data)) > 255) { /* max for unchar */
			spin_unlock_bh(&sl->lock);
			return -EINVAL;
		}
                if ((sl->outfill = (unchar)((unsigned long) rq->ifr_data)) != 0){
			mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
			set_bit(SLF_OUTWAIT, &sl->flags);
		} else {
                        del_timer (&sl->outfill_timer);
		}
                break;

        case SIOCGOUTFILL:
		rq->ifr_data=(caddr_t)((unsigned long)sl->outfill);
		break;

        case SIOCSLEASE:
		/* Resolve race condition, when ioctl'ing hanged up 
		   and opened by another process device.
		 */
		if (sl->tty != current->tty && sl->pid != current->pid) {
			spin_unlock_bh(&sl->lock);
			return -EPERM;
		}
		sl->leased = 0;
                if ((unsigned long)rq->ifr_data)
			sl->leased = 1;
                break;

        case SIOCGLEASE:
		rq->ifr_data=(caddr_t)((unsigned long)sl->leased);
	};
	spin_unlock_bh(&sl->lock);
	return 0;
}
#endif
/* VSV changes end */

/* Initialize SLIP control device -- register SLIP line discipline */

int __init slip_init_ctrl_dev(void)
{
	int status;

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

	printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
#ifdef CONFIG_SLIP_MODE_SLIP6
	       " (6 bit encapsulation enabled)"
#endif
	       ".\n",
	       SLIP_VERSION, slip_maxdev );
#if defined(SL_INCLUDE_CSLIP) && !defined(MODULE)
	printk("CSLIP: code copyright 1989 Regents of the University of California.\n");
#endif
#ifdef CONFIG_SLIP_SMART
	printk(KERN_INFO "SLIP linefill/keepalive option.\n");
#endif

	slip_ctrls = (slip_ctrl_t **) kmalloc(sizeof(void*)*slip_maxdev, GFP_KERNEL);
	if (slip_ctrls == NULL)
	{
		printk("SLIP: Can't allocate slip_ctrls[] array!  Uaargh! (-> No SLIP available)\n");
		return -ENOMEM;
	}

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

	/* Fill in our line protocol discipline, and register it */
	memset(&sl_ldisc, 0, sizeof(sl_ldisc));
	sl_ldisc.magic  = TTY_LDISC_MAGIC;
	sl_ldisc.name   = "slip";
	sl_ldisc.flags  = 0;
	sl_ldisc.open   = slip_open;
	sl_ldisc.close  = slip_close;
	sl_ldisc.read   = NULL;
	sl_ldisc.write  = NULL;
	sl_ldisc.ioctl  = (int (*)(struct tty_struct *, struct file *,
				   unsigned int, unsigned long)) slip_ioctl;
	sl_ldisc.poll   = NULL;
	sl_ldisc.receive_buf = slip_receive_buf;
	sl_ldisc.receive_room = slip_receive_room;
	sl_ldisc.write_wakeup = slip_write_wakeup;
	if ((status = tty_register_ldisc(N_SLIP, &sl_ldisc)) != 0)  {
		printk("SLIP: can't register line discipline (err = %d)\n", status);
	}


	return status;
}



#ifdef MODULE

int
init_module(void)
{
	return slip_init_ctrl_dev();
}

void
cleanup_module(void)
{
	int i;

	if (slip_ctrls != NULL) {
		unsigned long start = jiffies;
		int busy = 0;

		/* First of all: check for active disciplines and hangup them.
		 */
		do {
			if (busy) {
				current->counter = 0;
				schedule();
			}

			busy = 0;
			local_bh_disable();
			for (i = 0; i < slip_maxdev; i++) {
				struct slip_ctrl *slc = slip_ctrls[i];
				if (!slc)
					continue;
				spin_lock(&slc->ctrl.lock);
				if (slc->ctrl.tty) {
					busy++;
					tty_hangup(slc->ctrl.tty);
				}
				spin_unlock(&slc->ctrl.lock);
			}
			local_bh_enable();
		} while (busy && jiffies - start < 1*HZ);

		busy = 0;
		for (i = 0; i < slip_maxdev; i++) {
			struct slip_ctrl *slc = slip_ctrls[i];
			if (slc) {
				unregister_netdev(&slc->dev);
				if (slc->ctrl.tty) {
					printk("%s: tty discipline is still running\n", slc->dev.name);
					/* Pin module forever */
					MOD_INC_USE_COUNT;
					busy++;
					continue;
				}
				sl_free_bufs(&slc->ctrl);
				kfree(slc);
				slip_ctrls[i] = NULL;
			}
		}
		if (!busy) {
			kfree(slip_ctrls);
			slip_ctrls = NULL;
		}
	}
	if ((i = tty_register_ldisc(N_SLIP, NULL)))
	{
		printk("SLIP: can't unregister line discipline (err = %d)\n", i);
	}
}
#endif /* MODULE */

#ifdef CONFIG_SLIP_SMART
/*
 * This is start of the code for multislip style line checking
 * added by Stanislav Voronyi. All changes before marked VSV
 */

static void sl_outfill(unsigned long sls)
{
	struct slip *sl=(struct slip *)sls;

	spin_lock(&sl->lock);

	if (sl->tty == NULL)
		goto out;

	if(sl->outfill)
	{
		if( test_bit(SLF_OUTWAIT, &sl->flags) )
		{
			/* no packets were transmitted, do outfill */
#ifdef CONFIG_SLIP_MODE_SLIP6
			unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
#else
			unsigned char s = END;
#endif
			/* put END into tty queue. Is it right ??? */
			if (!netif_queue_stopped(sl->dev))
			{
				/* if device busy no outfill */
				sl->tty->driver.write(sl->tty, 0, &s, 1);
			}
		}
		else
			set_bit(SLF_OUTWAIT, &sl->flags);

		mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
	}
out:
	spin_unlock(&sl->lock);
}

static void sl_keepalive(unsigned long sls)
{
	struct slip *sl=(struct slip *)sls;

	spin_lock(&sl->lock);

	if (sl->tty == NULL)
		goto out;

	if( sl->keepalive)
	{
		if(test_bit(SLF_KEEPTEST, &sl->flags))
		{
			/* keepalive still high :(, we must hangup */
			if( sl->outfill ) /* outfill timer must be deleted too */
				(void)del_timer(&sl->outfill_timer);
			printk("%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
			tty_hangup(sl->tty); /* this must hangup tty & close slip */
			/* I think we need not something else */
			goto out;
		}
		else
			set_bit(SLF_KEEPTEST, &sl->flags);

		mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
	}

out:
	spin_unlock(&sl->lock);
}

#endif