/*********************************************************************
   *
   * Filename:      discovery.c
   * Version:       0.1
   * Description:   Routines for handling discoveries at the IrLMP layer
   * Status:        Experimental.
   * Author:        Dag Brattli <dagb@cs.uit.no>
   * Created at:    Tue Apr  6 15:33:50 1999
   * Modified at:   Sat Oct  9 17:11:31 1999
   * Modified by:   Dag Brattli <dagb@cs.uit.no>
   * Modified at:   Fri May 28  3:11 CST 1999
   * Modified by:   Horst von Brand <vonbrand@sleipnir.valparaiso.cl>
   *
   *     Copyright (c) 1999 Dag Brattli, All Rights Reserved.
   *
   *     This program 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 program is distributed in the hope that it will be useful,
   *     but WITHOUT ANY WARRANTY; without even the implied warranty of
   *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   *     GNU General Public License for more details.
   *
   *     You should have received a copy of the GNU General Public License
   *     along with this program; if not, see <http://www.gnu.org/licenses/>.
   *
   ********************************************************************/
  
  #include <linux/string.h>
  #include <linux/socket.h>
  #include <linux/fs.h>
  #include <linux/seq_file.h>
  #include <linux/slab.h>
  #include <linux/export.h>
  
  #include <net/irda/irda.h>
  #include <net/irda/irlmp.h>
  
  #include <net/irda/discovery.h>
  
  #include <asm/unaligned.h>
  
  /*
   * Function irlmp_add_discovery (cachelog, discovery)
   *
   *    Add a new discovery to the cachelog, and remove any old discoveries
   *    from the same device
   *
   * Note : we try to preserve the time this device was *first* discovered
   * (as opposed to the time of last discovery used for cleanup). This is
   * used by clients waiting for discovery events to tell if the device
   * discovered is "new" or just the same old one. They can't rely there
   * on a binary flag (new/old), because not all discovery events are
   * propagated to them, and they might not always listen, so they would
   * miss some new devices popping up...
   * Jean II
   */
  void irlmp_add_discovery(hashbin_t *cachelog, discovery_t *new)
  {
  	discovery_t *discovery, *node;
  	unsigned long flags;
  
  	/* Set time of first discovery if node is new (see below) */
  	new->firststamp = new->timestamp;
  
  	spin_lock_irqsave(&cachelog->hb_spinlock, flags);
  
  	/*
  	 * Remove all discoveries of devices that has previously been
  	 * discovered on the same link with the same name (info), or the
  	 * same daddr. We do this since some devices (mostly PDAs) change
  	 * their device address between every discovery.
  	 */
  	discovery = (discovery_t *) hashbin_get_first(cachelog);
  	while (discovery != NULL ) {
  		node = discovery;
  
  		/* Be sure to stay one item ahead */
  		discovery = (discovery_t *) hashbin_get_next(cachelog);
  
  		if ((node->data.saddr == new->data.saddr) &&
  		    ((node->data.daddr == new->data.daddr) ||
  		     (strcmp(node->data.info, new->data.info) == 0)))
  		{
  			/* This discovery is a previous discovery
  			 * from the same device, so just remove it
  			 */
  			hashbin_remove_this(cachelog, (irda_queue_t *) node);
  			/* Check if hints bits are unchanged */
  			if (get_unaligned((__u16 *)node->data.hints) == get_unaligned((__u16 *)new->data.hints))
  				/* Set time of first discovery for this node */
  				new->firststamp = node->firststamp;
  			kfree(node);
  		}
  	}
  
  	/* Insert the new and updated version */
  	hashbin_insert(cachelog, (irda_queue_t *) new, new->data.daddr, NULL);
  
  	spin_unlock_irqrestore(&cachelog->hb_spinlock, flags);
  }
  
  /*
   * Function irlmp_add_discovery_log (cachelog, log)
   *
   *    Merge a disovery log into the cachelog.
   *
   */
  void irlmp_add_discovery_log(hashbin_t *cachelog, hashbin_t *log)
  {
  	discovery_t *discovery;
  
  	IRDA_DEBUG(4, "%s()
  ", __func__);
  
  	/*
  	 *  If log is missing this means that IrLAP was unable to perform the
  	 *  discovery, so restart discovery again with just the half timeout
  	 *  of the normal one.
  	 */
  	/* Well... It means that there was nobody out there - Jean II */
  	if (log == NULL) {
  		/* irlmp_start_discovery_timer(irlmp, 150); */
  		return;
  	}
  
  	/*
  	 * Locking : we are the only owner of this discovery log, so
  	 * no need to lock it.
  	 * We just need to lock the global log in irlmp_add_discovery().
  	 */
  	discovery = (discovery_t *) hashbin_remove_first(log);
  	while (discovery != NULL) {
  		irlmp_add_discovery(cachelog, discovery);
  
  		discovery = (discovery_t *) hashbin_remove_first(log);
  	}
  
  	/* Delete the now empty log */
  	hashbin_delete(log, (FREE_FUNC) kfree);
  }
  
  /*
   * Function irlmp_expire_discoveries (log, saddr, force)
   *
   *    Go through all discoveries and expire all that has stayed too long
   *
   * Note : this assume that IrLAP won't change its saddr, which
   * currently is a valid assumption...
   */
  void irlmp_expire_discoveries(hashbin_t *log, __u32 saddr, int force)
  {
  	discovery_t *		discovery;
  	discovery_t *		curr;
  	unsigned long		flags;
  	discinfo_t *		buffer = NULL;
  	int			n;		/* Size of the full log */
  	int			i = 0;		/* How many we expired */
  
  	IRDA_ASSERT(log != NULL, return;);
  	IRDA_DEBUG(4, "%s()
  ", __func__);
  
  	spin_lock_irqsave(&log->hb_spinlock, flags);
  
  	discovery = (discovery_t *) hashbin_get_first(log);
  	while (discovery != NULL) {
  		/* Be sure to be one item ahead */
  		curr = discovery;
  		discovery = (discovery_t *) hashbin_get_next(log);
  
  		/* Test if it's time to expire this discovery */
  		if ((curr->data.saddr == saddr) &&
  		    (force ||
  		     ((jiffies - curr->timestamp) > DISCOVERY_EXPIRE_TIMEOUT)))
  		{
  			/* Create buffer as needed.
  			 * As this function get called a lot and most time
  			 * we don't have anything to put in the log (we are
  			 * quite picky), we can save a lot of overhead
  			 * by not calling kmalloc. Jean II */
  			if(buffer == NULL) {
  				/* Create the client specific buffer */
  				n = HASHBIN_GET_SIZE(log);
  				buffer = kmalloc(n * sizeof(struct irda_device_info), GFP_ATOMIC);
  				if (buffer == NULL) {
  					spin_unlock_irqrestore(&log->hb_spinlock, flags);
  					return;
  				}
  
  			}
  
  			/* Copy discovery information */
  			memcpy(&(buffer[i]), &(curr->data),
  			       sizeof(discinfo_t));
  			i++;
  
  			/* Remove it from the log */
  			curr = hashbin_remove_this(log, (irda_queue_t *) curr);
  			kfree(curr);
  		}
  	}
  
  	/* Drop the spinlock before calling the higher layers, as
  	 * we can't guarantee they won't call us back and create a
  	 * deadlock. We will work on our own private data, so we
  	 * don't care to be interrupted. - Jean II */
  	spin_unlock_irqrestore(&log->hb_spinlock, flags);
  
  	if(buffer == NULL)
  		return;
  
  	/* Tell IrLMP and registered clients about it */
  	irlmp_discovery_expiry(buffer, i);
  
  	/* Free up our buffer */
  	kfree(buffer);
  }
  
  #if 0
  /*
   * Function irlmp_dump_discoveries (log)
   *
   *    Print out all discoveries in log
   *
   */
  void irlmp_dump_discoveries(hashbin_t *log)
  {
  	discovery_t *discovery;
  
  	IRDA_ASSERT(log != NULL, return;);
  
  	discovery = (discovery_t *) hashbin_get_first(log);
  	while (discovery != NULL) {
  		IRDA_DEBUG(0, "Discovery:
  ");
  		IRDA_DEBUG(0, "  daddr=%08x
  ", discovery->data.daddr);
  		IRDA_DEBUG(0, "  saddr=%08x
  ", discovery->data.saddr);
  		IRDA_DEBUG(0, "  nickname=%s
  ", discovery->data.info);
  
  		discovery = (discovery_t *) hashbin_get_next(log);
  	}
  }
  #endif
  
  /*
   * Function irlmp_copy_discoveries (log, pn, mask)
   *
   *    Copy all discoveries in a buffer
   *
   * This function implement a safe way for lmp clients to access the
   * discovery log. The basic problem is that we don't want the log
   * to change (add/remove) while the client is reading it. If the
   * lmp client manipulate directly the hashbin, he is sure to get
   * into troubles...
   * The idea is that we copy all the current discovery log in a buffer
   * which is specific to the client and pass this copy to him. As we
   * do this operation with the spinlock grabbed, we are safe...
   * Note : we don't want those clients to grab the spinlock, because
   * we have no control on how long they will hold it...
   * Note : we choose to copy the log in "struct irda_device_info" to
   * save space...
   * Note : the client must kfree himself() the log...
   * Jean II
   */
  struct irda_device_info *irlmp_copy_discoveries(hashbin_t *log, int *pn,
  						__u16 mask, int old_entries)
  {
  	discovery_t *		discovery;
  	unsigned long		flags;
  	discinfo_t *		buffer = NULL;
  	int			j_timeout = (sysctl_discovery_timeout * HZ);
  	int			n;		/* Size of the full log */
  	int			i = 0;		/* How many we picked */
  
  	IRDA_ASSERT(pn != NULL, return NULL;);
  	IRDA_ASSERT(log != NULL, return NULL;);
  
  	/* Save spin lock */
  	spin_lock_irqsave(&log->hb_spinlock, flags);
  
  	discovery = (discovery_t *) hashbin_get_first(log);
  	while (discovery != NULL) {
  		/* Mask out the ones we don't want :
  		 * We want to match the discovery mask, and to get only
  		 * the most recent one (unless we want old ones) */
  		if ((get_unaligned((__u16 *)discovery->data.hints) & mask) &&
  		    ((old_entries) ||
  		     ((jiffies - discovery->firststamp) < j_timeout))) {
  			/* Create buffer as needed.
  			 * As this function get called a lot and most time
  			 * we don't have anything to put in the log (we are
  			 * quite picky), we can save a lot of overhead
  			 * by not calling kmalloc. Jean II */
  			if(buffer == NULL) {
  				/* Create the client specific buffer */
  				n = HASHBIN_GET_SIZE(log);
  				buffer = kmalloc(n * sizeof(struct irda_device_info), GFP_ATOMIC);
  				if (buffer == NULL) {
  					spin_unlock_irqrestore(&log->hb_spinlock, flags);
  					return NULL;
  				}
  
  			}
  
  			/* Copy discovery information */
  			memcpy(&(buffer[i]), &(discovery->data),
  			       sizeof(discinfo_t));
  			i++;
  		}
  		discovery = (discovery_t *) hashbin_get_next(log);
  	}
  
  	spin_unlock_irqrestore(&log->hb_spinlock, flags);
  
  	/* Get the actual number of device in the buffer and return */
  	*pn = i;
  	return buffer;
  }
  
  #ifdef CONFIG_PROC_FS
  static inline discovery_t *discovery_seq_idx(loff_t pos)
  
  {
  	discovery_t *discovery;
  
  	for (discovery = (discovery_t *) hashbin_get_first(irlmp->cachelog);
  	     discovery != NULL;
  	     discovery = (discovery_t *) hashbin_get_next(irlmp->cachelog)) {
  		if (pos-- == 0)
  			break;
  	}
  
  	return discovery;
  }
  
  static void *discovery_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	spin_lock_irq(&irlmp->cachelog->hb_spinlock);
  	return *pos ? discovery_seq_idx(*pos - 1) : SEQ_START_TOKEN;
  }
  
  static void *discovery_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	++*pos;
  	return (v == SEQ_START_TOKEN)
  		? (void *) hashbin_get_first(irlmp->cachelog)
  		: (void *) hashbin_get_next(irlmp->cachelog);
  }
  
  static void discovery_seq_stop(struct seq_file *seq, void *v)
  {
  	spin_unlock_irq(&irlmp->cachelog->hb_spinlock);
  }
  
  static int discovery_seq_show(struct seq_file *seq, void *v)
  {
  	if (v == SEQ_START_TOKEN)
  		seq_puts(seq, "IrLMP: Discovery log:
  
  ");
  	else {
  		const discovery_t *discovery = v;
  
  		seq_printf(seq, "nickname: %s, hint: 0x%02x%02x",
  			   discovery->data.info,
  			   discovery->data.hints[0],
  			   discovery->data.hints[1]);
  #if 0
  		if ( discovery->data.hints[0] & HINT_PNP)
  			seq_puts(seq, "PnP Compatible ");
  		if ( discovery->data.hints[0] & HINT_PDA)
  			seq_puts(seq, "PDA/Palmtop ");
  		if ( discovery->data.hints[0] & HINT_COMPUTER)
  			seq_puts(seq, "Computer ");
  		if ( discovery->data.hints[0] & HINT_PRINTER)
  			seq_puts(seq, "Printer ");
  		if ( discovery->data.hints[0] & HINT_MODEM)
  			seq_puts(seq, "Modem ");
  		if ( discovery->data.hints[0] & HINT_FAX)
  			seq_puts(seq, "Fax ");
  		if ( discovery->data.hints[0] & HINT_LAN)
  			seq_puts(seq, "LAN Access ");
  
  		if ( discovery->data.hints[1] & HINT_TELEPHONY)
  			seq_puts(seq, "Telephony ");
  		if ( discovery->data.hints[1] & HINT_FILE_SERVER)
  			seq_puts(seq, "File Server ");
  		if ( discovery->data.hints[1] & HINT_COMM)
  			seq_puts(seq, "IrCOMM ");
  		if ( discovery->data.hints[1] & HINT_OBEX)
  			seq_puts(seq, "IrOBEX ");
  #endif
  		seq_printf(seq,", saddr: 0x%08x, daddr: 0x%08x
  
  ",
  			       discovery->data.saddr,
  			       discovery->data.daddr);
  
  		seq_putc(seq, '
  ');
  	}
  	return 0;
  }
  
  static const struct seq_operations discovery_seq_ops = {
  	.start  = discovery_seq_start,
  	.next   = discovery_seq_next,
  	.stop   = discovery_seq_stop,
  	.show   = discovery_seq_show,
  };
  
  static int discovery_seq_open(struct inode *inode, struct file *file)
  {
  	IRDA_ASSERT(irlmp != NULL, return -EINVAL;);
  
  	return seq_open(file, &discovery_seq_ops);
  }
  
  const struct file_operations discovery_seq_fops = {
  	.owner		= THIS_MODULE,
  	.open           = discovery_seq_open,
  	.read           = seq_read,
  	.llseek         = seq_lseek,
  	.release	= seq_release,
  };
  #endif