/*********************************************************************

   *

   * Filename:      irlmp_frame.c
   * Version:       0.9
   * Description:   IrLMP frame implementation
   * Status:        Experimental.
   * Author:        Dag Brattli <dagb@cs.uit.no>
   * Created at:    Tue Aug 19 02:09:59 1997
   * Modified at:   Mon Dec 13 13:41:12 1999
   * Modified by:   Dag Brattli <dagb@cs.uit.no>

   *

   *     Copyright (c) 1998-1999 Dag Brattli <dagb@cs.uit.no>
   *     All Rights Reserved.
   *     Copyright (c) 2000-2003 Jean Tourrilhes <jt@hpl.hp.com>

   *
   *     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.
   *

   *     Neither Dag Brattli nor University of Tromsø admit liability nor

   *     provide warranty for any of this software. This material is

   *     provided "AS-IS" and at no charge.
   *
   ********************************************************************/

  #include <linux/skbuff.h>
  #include <linux/kernel.h>
  
  #include <net/irda/irda.h>
  #include <net/irda/irlap.h>
  #include <net/irda/timer.h>
  #include <net/irda/irlmp.h>
  #include <net/irda/irlmp_frame.h>
  #include <net/irda/discovery.h>

  static struct lsap_cb *irlmp_find_lsap(struct lap_cb *self, __u8 dlsap,

  				       __u8 slsap, int status, hashbin_t *);
  
  inline void irlmp_send_data_pdu(struct lap_cb *self, __u8 dlsap, __u8 slsap,
  				int expedited, struct sk_buff *skb)
  {
  	skb->data[0] = dlsap;
  	skb->data[1] = slsap;
  
  	if (expedited) {

  		pr_debug("%s(), sending expedited data
  ", __func__);

  		irlap_data_request(self->irlap, skb, TRUE);
  	} else
  		irlap_data_request(self->irlap, skb, FALSE);
  }
  
  /*
   * Function irlmp_send_lcf_pdu (dlsap, slsap, opcode,skb)
   *
   *    Send Link Control Frame to IrLAP
   */
  void irlmp_send_lcf_pdu(struct lap_cb *self, __u8 dlsap, __u8 slsap,

  			__u8 opcode, struct sk_buff *skb)

  {
  	__u8 *frame;

  	IRDA_ASSERT(self != NULL, return;);
  	IRDA_ASSERT(self->magic == LMP_LAP_MAGIC, return;);
  	IRDA_ASSERT(skb != NULL, return;);

  	frame = skb->data;

  	frame[0] = dlsap | CONTROL_BIT;
  	frame[1] = slsap;
  
  	frame[2] = opcode;
  
  	if (opcode == DISCONNECT)
  		frame[3] = 0x01; /* Service user request */
  	else
  		frame[3] = 0x00; /* rsvd */
  
  	irlap_data_request(self->irlap, skb, FALSE);
  }
  
  /*
   * Function irlmp_input (skb)
   *
   *    Used by IrLAP to pass received data frames to IrLMP layer
   *
   */

  void irlmp_link_data_indication(struct lap_cb *self, struct sk_buff *skb,

  				int unreliable)
  {
  	struct lsap_cb *lsap;
  	__u8   slsap_sel;   /* Source (this) LSAP address */
  	__u8   dlsap_sel;   /* Destination LSAP address */
  	__u8   *fp;

  	IRDA_ASSERT(self != NULL, return;);
  	IRDA_ASSERT(self->magic == LMP_LAP_MAGIC, return;);
  	IRDA_ASSERT(skb->len > 2, return;);
  
  	fp = skb->data;
  
  	/*

  	 *  The next statements may be confusing, but we do this so that

  	 *  destination LSAP of received frame is source LSAP in our view
  	 */

  	slsap_sel = fp[0] & LSAP_MASK;
  	dlsap_sel = fp[1];

  
  	/*
  	 *  Check if this is an incoming connection, since we must deal with
  	 *  it in a different way than other established connections.
  	 */
  	if ((fp[0] & CONTROL_BIT) && (fp[2] == CONNECT_CMD)) {

  		pr_debug("%s(), incoming connection, source LSAP=%d, dest LSAP=%d
  ",
  			 __func__, slsap_sel, dlsap_sel);

  		/* Try to find LSAP among the unconnected LSAPs */
  		lsap = irlmp_find_lsap(self, dlsap_sel, slsap_sel, CONNECT_CMD,
  				       irlmp->unconnected_lsaps);

  		/* Maybe LSAP was already connected, so try one more time */
  		if (!lsap) {

  			pr_debug("%s(), incoming connection for LSAP already connected
  ",
  				 __func__);

  			lsap = irlmp_find_lsap(self, dlsap_sel, slsap_sel, 0,
  					       self->lsaps);
  		}
  	} else

  		lsap = irlmp_find_lsap(self, dlsap_sel, slsap_sel, 0,

  				       self->lsaps);

  	if (lsap == NULL) {

  		pr_debug("IrLMP, Sorry, no LSAP for received frame!
  ");
  		pr_debug("%s(), slsap_sel = %02x, dlsap_sel = %02x
  ",
  			 __func__, slsap_sel, dlsap_sel);

  		if (fp[0] & CONTROL_BIT) {

  			pr_debug("%s(), received control frame %02x
  ",
  				 __func__, fp[2]);

  		} else {

  			pr_debug("%s(), received data frame
  ", __func__);

  		}
  		return;
  	}

  	/*
  	 *  Check if we received a control frame?

  	 */
  	if (fp[0] & CONTROL_BIT) {
  		switch (fp[2]) {
  		case CONNECT_CMD:
  			lsap->lap = self;
  			irlmp_do_lsap_event(lsap, LM_CONNECT_INDICATION, skb);
  			break;
  		case CONNECT_CNF:
  			irlmp_do_lsap_event(lsap, LM_CONNECT_CONFIRM, skb);
  			break;
  		case DISCONNECT:

  			pr_debug("%s(), Disconnect indication!
  ",
  				 __func__);

  			irlmp_do_lsap_event(lsap, LM_DISCONNECT_INDICATION,

  					    skb);
  			break;
  		case ACCESSMODE_CMD:

  			pr_debug("Access mode cmd not implemented!
  ");

  			break;
  		case ACCESSMODE_CNF:

  			pr_debug("Access mode cnf not implemented!
  ");

  			break;
  		default:

  			pr_debug("%s(), Unknown control frame %02x
  ",
  				 __func__, fp[2]);

  			break;
  		}
  	} else if (unreliable) {
  		/* Optimize and bypass the state machine if possible */
  		if (lsap->lsap_state == LSAP_DATA_TRANSFER_READY)
  			irlmp_udata_indication(lsap, skb);
  		else
  			irlmp_do_lsap_event(lsap, LM_UDATA_INDICATION, skb);

  	} else {

  		/* Optimize and bypass the state machine if possible */
  		if (lsap->lsap_state == LSAP_DATA_TRANSFER_READY)
  			irlmp_data_indication(lsap, skb);
  		else
  			irlmp_do_lsap_event(lsap, LM_DATA_INDICATION, skb);
  	}
  }
  
  /*
   * Function irlmp_link_unitdata_indication (self, skb)
   *

   *

   *
   */
  #ifdef CONFIG_IRDA_ULTRA
  void irlmp_link_unitdata_indication(struct lap_cb *self, struct sk_buff *skb)
  {
  	struct lsap_cb *lsap;
  	__u8   slsap_sel;   /* Source (this) LSAP address */
  	__u8   dlsap_sel;   /* Destination LSAP address */
  	__u8   pid;         /* Protocol identifier */
  	__u8   *fp;
  	unsigned long flags;

  	IRDA_ASSERT(self != NULL, return;);
  	IRDA_ASSERT(self->magic == LMP_LAP_MAGIC, return;);
  	IRDA_ASSERT(skb->len > 2, return;);
  
  	fp = skb->data;
  
  	/*

  	 *  The next statements may be confusing, but we do this so that

  	 *  destination LSAP of received frame is source LSAP in our view
  	 */

  	slsap_sel = fp[0] & LSAP_MASK;

  	dlsap_sel = fp[1];
  	pid       = fp[2];

  	if (pid & 0x80) {

  		pr_debug("%s(), extension in PID not supp!
  ",
  			 __func__);

  		return;
  	}
  
  	/* Check if frame is addressed to the connectionless LSAP */
  	if ((slsap_sel != LSAP_CONNLESS) || (dlsap_sel != LSAP_CONNLESS)) {

  		pr_debug("%s(), dropping frame!
  ", __func__);

  		return;
  	}

  	/* Search the connectionless LSAP */
  	spin_lock_irqsave(&irlmp->unconnected_lsaps->hb_spinlock, flags);
  	lsap = (struct lsap_cb *) hashbin_get_first(irlmp->unconnected_lsaps);
  	while (lsap != NULL) {
  		/*
  		 *  Check if source LSAP and dest LSAP selectors and PID match.
  		 */

  		if ((lsap->slsap_sel == slsap_sel) &&
  		    (lsap->dlsap_sel == dlsap_sel) &&
  		    (lsap->pid == pid))
  		{

  			break;
  		}
  		lsap = (struct lsap_cb *) hashbin_get_next(irlmp->unconnected_lsaps);
  	}
  	spin_unlock_irqrestore(&irlmp->unconnected_lsaps->hb_spinlock, flags);
  
  	if (lsap)
  		irlmp_connless_data_indication(lsap, skb);
  	else {

  		pr_debug("%s(), found no matching LSAP!
  ", __func__);

  	}
  }
  #endif /* CONFIG_IRDA_ULTRA */
  
  /*
   * Function irlmp_link_disconnect_indication (reason, userdata)
   *

   *    IrLAP has disconnected

   *
   */

  void irlmp_link_disconnect_indication(struct lap_cb *lap,
  				      struct irlap_cb *irlap,
  				      LAP_REASON reason,

  				      struct sk_buff *skb)
  {

  	IRDA_ASSERT(lap != NULL, return;);
  	IRDA_ASSERT(lap->magic == LMP_LAP_MAGIC, return;);
  
  	lap->reason = reason;
  	lap->daddr = DEV_ADDR_ANY;

  	/* FIXME: must do something with the skb if any */

  	/*
  	 *  Inform station state machine
  	 */
  	irlmp_do_lap_event(lap, LM_LAP_DISCONNECT_INDICATION, NULL);
  }
  
  /*
   * Function irlmp_link_connect_indication (qos)
   *
   *    Incoming LAP connection!
   *
   */

  void irlmp_link_connect_indication(struct lap_cb *self, __u32 saddr,

  				   __u32 daddr, struct qos_info *qos,

  				   struct sk_buff *skb)

  {

  	/* Copy QoS settings for this session */
  	self->qos = qos;
  
  	/* Update destination device address */
  	self->daddr = daddr;
  	IRDA_ASSERT(self->saddr == saddr, return;);
  
  	irlmp_do_lap_event(self, LM_LAP_CONNECT_INDICATION, skb);
  }
  
  /*
   * Function irlmp_link_connect_confirm (qos)
   *
   *    LAP connection confirmed!
   *
   */

  void irlmp_link_connect_confirm(struct lap_cb *self, struct qos_info *qos,

  				struct sk_buff *skb)
  {

  	IRDA_ASSERT(self != NULL, return;);
  	IRDA_ASSERT(self->magic == LMP_LAP_MAGIC, return;);
  	IRDA_ASSERT(qos != NULL, return;);
  
  	/* Don't need use the skb for now */
  
  	/* Copy QoS settings for this session */
  	self->qos = qos;
  
  	irlmp_do_lap_event(self, LM_LAP_CONNECT_CONFIRM, NULL);
  }
  
  /*
   * Function irlmp_link_discovery_indication (self, log)
   *
   *    Device is discovering us
   *
   * It's not an answer to our own discoveries, just another device trying
   * to perform discovery, but we don't want to miss the opportunity
   * to exploit this information, because :
   *	o We may not actively perform discovery (just passive discovery)
   *	o This type of discovery is much more reliable. In some cases, it
   *	  seem that less than 50% of our discoveries get an answer, while
   *	  we always get ~100% of these.
   *	o Make faster discovery, statistically divide time of discovery
   *	  events by 2 (important for the latency aspect and user feel)
   *	o Even is we do active discovery, the other node might not
   *	  answer our discoveries (ex: Palm). The Palm will just perform
   *	  one active discovery and connect directly to us.
   *
   * However, when both devices discover each other, they might attempt to
   * connect to each other following the discovery event, and it would create
   * collisions on the medium (SNRM battle).
   * The "fix" for that is to disable all connection requests in IrLAP
   * for 100ms after a discovery indication by setting the media_busy flag.
   * Previously, we used to postpone the event which was quite ugly. Now
   * that IrLAP takes care of this problem, just pass the event up...
   *
   * Jean II
   */

  void irlmp_link_discovery_indication(struct lap_cb *self,

  				     discovery_t *discovery)
  {
  	IRDA_ASSERT(self != NULL, return;);
  	IRDA_ASSERT(self->magic == LMP_LAP_MAGIC, return;);
  
  	/* Add to main log, cleanup */
  	irlmp_add_discovery(irlmp->cachelog, discovery);

  	/* Just handle it the same way as a discovery confirm,
  	 * bypass the LM_LAP state machine (see below) */
  	irlmp_discovery_confirm(irlmp->cachelog, DISCOVERY_PASSIVE);
  }
  
  /*
   * Function irlmp_link_discovery_confirm (self, log)
   *
   *    Called by IrLAP with a list of discoveries after the discovery
   *    request has been carried out. A NULL log is received if IrLAP
   *    was unable to carry out the discovery request
   *
   */
  void irlmp_link_discovery_confirm(struct lap_cb *self, hashbin_t *log)
  {

  	IRDA_ASSERT(self != NULL, return;);
  	IRDA_ASSERT(self->magic == LMP_LAP_MAGIC, return;);

  	/* Add to main log, cleanup */
  	irlmp_add_discovery_log(irlmp->cachelog, log);
  
  	/* Propagate event to various LSAPs registered for it.
  	 * We bypass the LM_LAP state machine because
  	 *	1) We do it regardless of the LM_LAP state
  	 *	2) It doesn't affect the LM_LAP state
  	 *	3) Faster, slimer, simpler, ...
  	 * Jean II */
  	irlmp_discovery_confirm(irlmp->cachelog, DISCOVERY_ACTIVE);
  }
  
  #ifdef CONFIG_IRDA_CACHE_LAST_LSAP
  static inline void irlmp_update_cache(struct lap_cb *lap,
  				      struct lsap_cb *lsap)
  {
  	/* Prevent concurrent read to get garbage */
  	lap->cache.valid = FALSE;
  	/* Update cache entry */
  	lap->cache.dlsap_sel = lsap->dlsap_sel;
  	lap->cache.slsap_sel = lsap->slsap_sel;
  	lap->cache.lsap = lsap;
  	lap->cache.valid = TRUE;
  }
  #endif
  
  /*
   * Function irlmp_find_handle (self, dlsap_sel, slsap_sel, status, queue)
   *
   *    Find handle associated with destination and source LSAP
   *
   * Any IrDA connection (LSAP/TSAP) is uniquely identified by

   * 3 parameters, the local lsap, the remote lsap and the remote address.

   * We may initiate multiple connections to the same remote service
   * (they will have different local lsap), a remote device may initiate
   * multiple connections to the same local service (they will have
   * different remote lsap), or multiple devices may connect to the same
   * service and may use the same remote lsap (and they will have
   * different remote address).
   * So, where is the remote address ? Each LAP connection is made with
   * a single remote device, so imply a specific remote address.
   * Jean II
   */
  static struct lsap_cb *irlmp_find_lsap(struct lap_cb *self, __u8 dlsap_sel,
  				       __u8 slsap_sel, int status,

  				       hashbin_t *queue)

  {
  	struct lsap_cb *lsap;
  	unsigned long flags;

  
  	/*

  	 *  Optimize for the common case. We assume that the last frame
  	 *  received is in the same connection as the last one, so check in
  	 *  cache first to avoid the linear search
  	 */
  #ifdef CONFIG_IRDA_CACHE_LAST_LSAP

  	if ((self->cache.valid) &&
  	    (self->cache.slsap_sel == slsap_sel) &&
  	    (self->cache.dlsap_sel == dlsap_sel))

  	{

  		return self->cache.lsap;

  	}
  #endif
  
  	spin_lock_irqsave(&queue->hb_spinlock, flags);
  
  	lsap = (struct lsap_cb *) hashbin_get_first(queue);
  	while (lsap != NULL) {

  		/*
  		 *  If this is an incoming connection, then the destination
  		 *  LSAP selector may have been specified as LM_ANY so that

  		 *  any client can connect. In that case we only need to check
  		 *  if the source LSAP (in our view!) match!
  		 */

  		if ((status == CONNECT_CMD) &&
  		    (lsap->slsap_sel == slsap_sel) &&

  		    (lsap->dlsap_sel == LSAP_ANY)) {
  			/* This is where the dest lsap sel is set on incoming
  			 * lsaps */
  			lsap->dlsap_sel = dlsap_sel;
  			break;
  		}
  		/*
  		 *  Check if source LSAP and dest LSAP selectors match.
  		 */

  		if ((lsap->slsap_sel == slsap_sel) &&
  		    (lsap->dlsap_sel == dlsap_sel))

  			break;
  
  		lsap = (struct lsap_cb *) hashbin_get_next(queue);
  	}
  #ifdef CONFIG_IRDA_CACHE_LAST_LSAP
  	if(lsap)
  		irlmp_update_cache(self, lsap);
  #endif
  	spin_unlock_irqrestore(&queue->hb_spinlock, flags);
  
  	/* Return what we've found or NULL */
  	return lsap;
  }