irlmp_frame.c

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/*********************************************************************
 *
 * Filename:      irlmp_frame.c
 * Version:       0.9
 * Description:   IrLMP frame implementation
 * Status:        Experimental.
 * Author:        Dag Brattli <[email protected]>
 * Created at:    Tue Aug 19 02:09:59 1997
 * Modified at:   Mon Dec 13 13:41:12 1999
 * Modified by:   Dag Brattli <[email protected]>
 *
 *     Copyright (c) 1998-1999 Dag Brattli <[email protected]>
 *     All Rights Reserved.
 *     Copyright (c) 2000-2003 Jean Tourrilhes <[email protected]>
 *
 *     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) {
        IRDA_DEBUG(4, "%s(), sending expedited data\n", __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_DEBUG(2, "%s()\n", __func__);

    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_DEBUG(4, "%s()\n", __func__);

    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)) {
        IRDA_DEBUG(3, "%s(), incoming connection, "
               "source LSAP=%d, dest LSAP=%d\n",
               __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) {
            IRDA_DEBUG(1, "%s(), incoming connection for LSAP already connected\n", __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) {
        IRDA_DEBUG(2, "IrLMP, Sorry, no LSAP for received frame!\n");
        IRDA_DEBUG(2, "%s(), slsap_sel = %02x, dlsap_sel = %02x\n",
               __func__, slsap_sel, dlsap_sel);
        if (fp[0] & CONTROL_BIT) {
            IRDA_DEBUG(2, "%s(), received control frame %02x\n",
                   __func__, fp[2]);
        } else {
            IRDA_DEBUG(2, "%s(), received data frame\n", __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:
            IRDA_DEBUG(4, "%s(), Disconnect indication!\n",
                   __func__);
            irlmp_do_lsap_event(lsap, LM_DISCONNECT_INDICATION,
                        skb);
            break;
        case ACCESSMODE_CMD:
            IRDA_DEBUG(0, "Access mode cmd not implemented!\n");
            break;
        case ACCESSMODE_CNF:
            IRDA_DEBUG(0, "Access mode cnf not implemented!\n");
            break;
        default:
            IRDA_DEBUG(0, "%s(), Unknown control frame %02x\n",
                   __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_DEBUG(4, "%s()\n", __func__);

    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) {
        IRDA_DEBUG(0, "%s(), extension in PID not supp!\n",
               __func__);
        return;
    }

    /* Check if frame is addressed to the connectionless LSAP */
    if ((slsap_sel != LSAP_CONNLESS) || (dlsap_sel != LSAP_CONNLESS)) {
        IRDA_DEBUG(0, "%s(), dropping frame!\n", __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 {
        IRDA_DEBUG(0, "%s(), found no matching LSAP!\n", __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_DEBUG(2, "%s()\n", __func__);

    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)
{
    IRDA_DEBUG(4, "%s()\n", __func__);

    /* 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_DEBUG(4, "%s()\n", __func__);

    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_DEBUG(4, "%s()\n", __func__);

    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;
}