irnet_ppp.c

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/*
 *	IrNET protocol module : Synchronous PPP over an IrDA socket.
 *
 *		Jean II - HPL `00 - <[e-mail]>
 *
 * This file implement the PPP interface and /dev/irnet character device.
 * The PPP interface hook to the ppp_generic module, handle all our
 *	relationship to the PPP code in the kernel (and by extension to pppd),
 *	and exchange PPP frames with this module (send/receive).
 * The /dev/irnet device is used primarily for 2 functions :
 *	1) as a stub for pppd (the ppp daemon), so that we can appropriately
 *	generate PPP sessions (we pretend we are a tty).
 *	2) as a control channel (write commands, read events)
 */

#include "irnet_ppp.h"		/* Private header */

/************************* CONTROL CHANNEL *************************/
/*
 * When a pppd instance is not active on /dev/irnet, it acts as a control
 * channel.
 * Writting allow to set up the IrDA destination of the IrNET channel,
 * and any application may be read events happening in IrNET...
 */

/*------------------------------------------------------------------*/
/*
 * Write is used to send a command to configure a IrNET channel
 * before it is open by pppd. The syntax is : "command argument"
 * Currently there is only two defined commands :
 *	o name : set the requested IrDA nickname of the IrNET peer.
 *	o addr : set the requested IrDA address of the IrNET peer.
 * Note : the code is crude, but effective...
 */
static inline ssize_t
irnet_ctrl_write(irnet_socket *	ap,
		 const char *	buf,
		 size_t		count)
{
  char		command[5 + NICKNAME_MAX_LEN + 2];
  int		length = count;

  DENTER(CTRL_TRACE, "(ap=0x%X, count=%d)\n", (unsigned int) ap, count);

  /* Check for overflow... */
  DABORT(count > (5 + NICKNAME_MAX_LEN + 1), -ENOMEM,
	 CTRL_ERROR, "Too much data !!!\n");

  /* Get the data in the driver */
  if(copy_from_user(command, buf, count))
    {
      DERROR(CTRL_ERROR, "Invalid user space pointer.\n");
      return -EFAULT;
    }

  /* Strip out '\n' if needed, and safe terminate the string */
  if(command[length - 1] == '\0')
    length--;
  if(command[length - 1] == '\n')
    length--;
  command[length] = '\0';
  DEBUG(CTRL_INFO, "Command received is ``%s'' (%d-%d).\n",
	command, length, count);

  /* Check if we recognised the command */
  /* First command : name */
  if(!strncmp(command, "name", 4))
    {
      /* Copy the name only if is included and not "any" */
      if((length > 5) && (strcmp(command + 5, "any")))
	{
	  /* Copy the name for later reuse (including the '/0') */
	  memcpy(ap->rname, command + 5, length - 5 + 1);
	}
      else
	ap->rname[0] = '\0';
      DEXIT(CTRL_TRACE, " - rname = ``%s''\n", ap->rname);
      return(count);
    }

  /* Second command : addr */
  if(!strncmp(command, "addr", 4))
    {
      /* Copy the address only if is included and not "any" */
      if((length > 5) && (strcmp(command + 5, "any")))
	{
	  char *	endp;
	  __u32		daddr;

	  /* Convert argument to a number (last arg is the base) */
	  daddr = simple_strtoul(command + 5, &endp, 16);
	  /* Has it worked  ? (endp should be command + count) */
	  DABORT(endp <= (command + 5), -EINVAL,
		 CTRL_ERROR, "Invalid address.\n");
	  /* Save it */
	  ap->raddr = daddr;
	}
      else
	ap->raddr = DEV_ADDR_ANY;
      DEXIT(CTRL_TRACE, " - raddr = %08x\n", ap->raddr);
      return(count);
    }

  /* Other possible command : connect N (number of retries) */

  /* Failed... */
  DABORT(1, -EINVAL, CTRL_ERROR, "Not a recognised IrNET command.\n");
}

#ifdef INITIAL_DISCOVERY
/*------------------------------------------------------------------*/
/*
 * Function irnet_read_discovery_log (self)
 *
 *    Read the content on the discovery log
 *
 * This function dump the current content of the discovery log
 * at the startup of the event channel.
 * Return 1 if written on the control channel...
 *
 * State of the ap->disco_XXX variables :
 *	at socket creation :	disco_index = 0 ; disco_number = 0
 *	while reading :		disco_index = X ; disco_number = Y
 *	After reading :		disco_index = Y ; disco_number = -1
 */
static inline int
irnet_read_discovery_log(irnet_socket *	ap,
			 char *		event)
{
  int		done_event = 0;

  DENTER(CTRL_TRACE, "(ap=0x%X, event=0x%X)\n",
	 (unsigned int) ap, (unsigned int) event);

  /* Test if we have some work to do or we have already finished */
  if(ap->disco_number == -1)
    {
      DEBUG(CTRL_INFO, "Already done\n");
      return 0;
    }

  /* Test if it's the first time and therefore we need to get the log */
  if(ap->disco_index == 0)
    {
      __u16		mask = irlmp_service_to_hint(S_LAN);

      /* Ask IrLMP for the current discovery log */
      ap->discoveries = irlmp_get_discoveries(&ap->disco_number, mask);
      /* Check if the we got some results */
      if(ap->discoveries == NULL)
	ap->disco_number = -1;
      DEBUG(CTRL_INFO, "Got the log (0x%X), size is %d\n",
	    (unsigned int) ap->discoveries, ap->disco_number);
    }

  /* Check if we have more item to dump */
  if(ap->disco_index < ap->disco_number)
    {
      /* Write an event */
      sprintf(event, "Found %08x (%s)\n",
	      ap->discoveries[ap->disco_index].daddr,
	      ap->discoveries[ap->disco_index].info);
      DEBUG(CTRL_INFO, "Writing discovery %d : %s\n",
	    ap->disco_index, ap->discoveries[ap->disco_index].info);

      /* We have an event */
      done_event = 1;
      /* Next discovery */
      ap->disco_index++;
    }

  /* Check if we have done the last item */
  if(ap->disco_index >= ap->disco_number)
    {
      /* No more items : remove the log and signal termination */
      DEBUG(CTRL_INFO, "Cleaning up log (0x%X)\n",
	    (unsigned int) ap->discoveries);
      if(ap->discoveries != NULL)
	{
	  /* Cleanup our copy of the discovery log */
	  kfree(ap->discoveries);
	  ap->discoveries = NULL;
	}
      ap->disco_number = -1;
    }

  return done_event;
}
#endif INITIAL_DISCOVERY

/*------------------------------------------------------------------*/
/*
 * Read is used to get IrNET events
 */
static inline ssize_t
irnet_ctrl_read(irnet_socket *	ap,
		struct file *	file,
		char *		buf,
		size_t		count)
{
  DECLARE_WAITQUEUE(wait, current);
  char		event[64];	/* Max event is 61 char */
  ssize_t	ret = 0;

  DENTER(CTRL_TRACE, "(ap=0x%X, count=%d)\n", (unsigned int) ap, count);

  /* Check if we can write an event out in one go */
  DABORT(count < sizeof(event), -EOVERFLOW, CTRL_ERROR, "Buffer to small.\n");

#ifdef INITIAL_DISCOVERY
  /* Check if we have read the log */
  if(irnet_read_discovery_log(ap, event))
    {
      /* We have an event !!! Copy it to the user */
      if(copy_to_user(buf, event, strlen(event)))
	{
	  DERROR(CTRL_ERROR, "Invalid user space pointer.\n");
	  return -EFAULT;
	}

      DEXIT(CTRL_TRACE, "\n");
      return(strlen(event));
    }
#endif INITIAL_DISCOVERY

  /* Put ourselves on the wait queue to be woken up */
  add_wait_queue(&irnet_events.rwait, &wait);
  current->state = TASK_INTERRUPTIBLE;
  for(;;)
    {
      /* If there is unread events */
      ret = 0;
      if(ap->event_index != irnet_events.index)
	break;
      ret = -EAGAIN;
      if(file->f_flags & O_NONBLOCK)
	break;
      ret = -ERESTARTSYS;
      if(signal_pending(current))
	break;
      /* Yield and wait to be woken up */
      schedule();
    }
  current->state = TASK_RUNNING;
  remove_wait_queue(&irnet_events.rwait, &wait);

  /* Did we got it ? */
  if(ret != 0)
    {
      /* No, return the error code */
      DEXIT(CTRL_TRACE, " - ret %d\n", ret);
      return ret;
    }

  /* Which event is it ? */
  switch(irnet_events.log[ap->event_index].event)
    {
    case IRNET_DISCOVER:
      sprintf(event, "Discovered %08x (%s)\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name);
      break;
    case IRNET_EXPIRE:
      sprintf(event, "Expired %08x (%s)\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name);
      break;
    case IRNET_CONNECT_TO:
      sprintf(event, "Connected to %08x (%s) on ppp%d\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name,
	      irnet_events.log[ap->event_index].unit);
      break;
    case IRNET_CONNECT_FROM:
      sprintf(event, "Connection from %08x (%s) on ppp%d\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name,
	      irnet_events.log[ap->event_index].unit);
      break;
    case IRNET_REQUEST_FROM:
      sprintf(event, "Request from %08x (%s)\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name);
      break;
    case IRNET_NOANSWER_FROM:
      sprintf(event, "No-answer from %08x (%s) on ppp%d\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name,
	      irnet_events.log[ap->event_index].unit);
      break;
    case IRNET_BLOCKED_LINK:
      sprintf(event, "Blocked link with %08x (%s) on ppp%d\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name,
	      irnet_events.log[ap->event_index].unit);
      break;
    case IRNET_DISCONNECT_FROM:
      sprintf(event, "Disconnection from %08x (%s) on ppp%d\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name,
	      irnet_events.log[ap->event_index].unit);
      break;
    case IRNET_DISCONNECT_TO:
      sprintf(event, "Disconnected to %08x (%s)\n",
	      irnet_events.log[ap->event_index].addr,
	      irnet_events.log[ap->event_index].name);
      break;
    default:
      sprintf(event, "Bug\n");
    }
  /* Increment our event index */
  ap->event_index = (ap->event_index + 1) % IRNET_MAX_EVENTS;

  DEBUG(CTRL_INFO, "Event is :%s", event);

  /* Copy it to the user */
  if(copy_to_user(buf, event, strlen(event)))
    {
      DERROR(CTRL_ERROR, "Invalid user space pointer.\n");
      return -EFAULT;
    }

  DEXIT(CTRL_TRACE, "\n");
  return(strlen(event));
}

/*------------------------------------------------------------------*/
/*
 * Poll : called when someone do a select on /dev/irnet.
 * Just check if there are new events...
 */
static inline unsigned int
irnet_ctrl_poll(irnet_socket *	ap,
		struct file *	file,
		poll_table *	wait)
{
  unsigned int mask;

  DENTER(CTRL_TRACE, "(ap=0x%X)\n", (unsigned int) ap);

  poll_wait(file, &irnet_events.rwait, wait);
  mask = POLLOUT | POLLWRNORM;
  /* If there is unread events */
  if(ap->event_index != irnet_events.index)
    mask |= POLLIN | POLLRDNORM;
#ifdef INITIAL_DISCOVERY
  if(ap->disco_number != -1)
    mask |= POLLIN | POLLRDNORM;
#endif INITIAL_DISCOVERY

  DEXIT(CTRL_TRACE, " - mask=0x%X\n", mask);
  return mask;
}


/*********************** FILESYSTEM CALLBACKS ***********************/
/*
 * Implement the usual open, read, write functions that will be called
 * by the file system when some action is performed on /dev/irnet.
 * Most of those actions will in fact be performed by "pppd" or
 * the control channel, we just act as a redirector...
 */

/*------------------------------------------------------------------*/
/*
 * Open : when somebody open /dev/irnet
 * We basically create a new instance of irnet and initialise it.
 */
static int
dev_irnet_open(struct inode *	inode,
	       struct file *	file)
{
  struct irnet_socket *	ap;
  int			err;

  DENTER(FS_TRACE, "(file=0x%X)\n", (unsigned int) file);

#ifdef SECURE_DEVIRNET
  /* This could (should?) be enforced by the permissions on /dev/irnet. */
  if(!capable(CAP_NET_ADMIN))
    return -EPERM;
#endif SECURE_DEVIRNET

  /* Allocate a private structure for this IrNET instance */
  ap = kmalloc(sizeof(*ap), GFP_KERNEL);
  DABORT(ap == NULL, -ENOMEM, FS_ERROR, "Can't allocate struct irnet...\n");

  MOD_INC_USE_COUNT;

  /* initialize the irnet structure */
  memset(ap, 0, sizeof(*ap));
  ap->file = file;

  /* PPP channel setup */
  ap->ppp_open = 0;
  ap->chan.private = ap;
  /* PPP parameters */
  ap->mru = PPP_MRU;
  ap->xaccm[0] = ~0U;
  ap->xaccm[3] = 0x60000000U;
  ap->raccm = ~0U;

  /* Setup the IrDA part... */
  err = irda_irnet_create(ap);
  if(err)
    {
      DERROR(FS_ERROR, "Can't setup IrDA link...\n");
      kfree(ap);
      MOD_DEC_USE_COUNT;
      return err;
    }

  /* For the control channel */
  ap->event_index = irnet_events.index;	/* Cancel all past events */

  /* Put our stuff where we will be able to find it later */
  file->private_data = ap;

  DEXIT(FS_TRACE, " - ap=0x%X\n", (unsigned int) ap);
  return 0;
}


/*------------------------------------------------------------------*/
/*
 * Close : when somebody close /dev/irnet
 * Destroy the instance of /dev/irnet
 */
static int
dev_irnet_close(struct inode *	inode,
		struct file *	file)
{
  irnet_socket *	ap = (struct irnet_socket *) file->private_data;

  DENTER(FS_TRACE, "(file=0x%X, ap=0x%X)\n",
	 (unsigned int) file, (unsigned int) ap);
  DABORT(ap == NULL, 0, FS_ERROR, "ap is NULL !!!\n");

  /* Detach ourselves */
  file->private_data = NULL;

  /* Close IrDA stuff */
  irda_irnet_destroy(ap);

  /* Disconnect from the generic PPP layer if not already done */
  if(ap->ppp_open)
    {
      DERROR(FS_ERROR, "Channel still registered - deregistering !\n");
      ppp_unregister_channel(&ap->chan);
      ap->ppp_open = 0;
    }

  kfree(ap);
  MOD_DEC_USE_COUNT;

  DEXIT(FS_TRACE, "\n");
  return 0;
}

/*------------------------------------------------------------------*/
/*
 * Write does nothing.
 * (we receive packet from ppp_generic through ppp_irnet_send())
 */
static ssize_t
dev_irnet_write(struct file *	file,
		const char *	buf,
		size_t		count,
		loff_t *	ppos)
{
  irnet_socket *	ap = (struct irnet_socket *) file->private_data;

  DPASS(FS_TRACE, "(file=0x%X, ap=0x%X, count=%d)\n",
	(unsigned int) file, (unsigned int) ap, count);
  DABORT(ap == NULL, -ENXIO, FS_ERROR, "ap is NULL !!!\n");

  /* If we are connected to ppp_generic, let it handle the job */
  if(ap->ppp_open)
    return ppp_channel_write(&ap->chan, buf, count);
  else
    return irnet_ctrl_write(ap, buf, count);
}

/*------------------------------------------------------------------*/
/*
 * Read doesn't do much either.
 * (pppd poll us, but ultimately reads through /dev/ppp)
 */
static ssize_t
dev_irnet_read(struct file *	file,
	       char *		buf,
	       size_t		count,
	       loff_t *		ppos)
{
  irnet_socket *	ap = (struct irnet_socket *) file->private_data;

  DPASS(FS_TRACE, "(file=0x%X, ap=0x%X, count=%d)\n",
	(unsigned int) file, (unsigned int) ap, count);
  DABORT(ap == NULL, -ENXIO, FS_ERROR, "ap is NULL !!!\n");

  /* If we are connected to ppp_generic, let it handle the job */
  if(ap->ppp_open)
    return ppp_channel_read(&ap->chan, file, buf, count);
  else
    return irnet_ctrl_read(ap, file, buf, count);
}

/*------------------------------------------------------------------*/
/*
 * Poll : called when someone do a select on /dev/irnet
 */
static unsigned int
dev_irnet_poll(struct file *	file,
	       poll_table *	wait)
{
  irnet_socket *	ap = (struct irnet_socket *) file->private_data;
  unsigned int		mask;

  DENTER(FS_TRACE, "(file=0x%X, ap=0x%X)\n",
	 (unsigned int) file, (unsigned int) ap);

  mask = POLLOUT | POLLWRNORM;
  DABORT(ap == NULL, mask, FS_ERROR, "ap is NULL !!!\n");

  /* If we are connected to ppp_generic, let it handle the job */
  if(ap->ppp_open)
    mask |= ppp_channel_poll(&ap->chan, file, wait);