irlap_frame.c

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/*********************************************************************
 *                
 * Filename:      irlap_frame.c
 * Version:       1.0
 * Description:   Build and transmit IrLAP frames
 * Status:        Stable
 * Author:        Dag Brattli <dagb@cs.uit.no>
 * Created at:    Tue Aug 19 10:27:26 1997
 * Modified at:   Thu Apr 13 02:40:49 2000
 * Modified by:   Dag Brattli <dagb@cs.uit.no>
 * 
 *     Copyright (c) 1998-2000 Dag Brattli <dagb@cs.uit.no>, 
 *     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.
 *
 *     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/if.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/irda.h>
 
#include <net/pkt_sched.h>
#include <net/sock.h>
 
#include <asm/byteorder.h>

#include <net/irda/irda.h>
#include <net/irda/irda_device.h>
#include <net/irda/irlap.h>
#include <net/irda/wrapper.h>
#include <net/irda/timer.h>
#include <net/irda/irlap_frame.h>
#include <net/irda/qos.h>

/*
 * Function irlap_insert_info (self, skb)
 *
 *    Insert minimum turnaround time and speed information into the skb. We 
 *    need to do this since it's per packet relevant information. Safe to
 *    have this function inlined since it's only called from one place
 */
static inline void irlap_insert_info(struct irlap_cb *self, 
                                     struct sk_buff *skb)
{
        struct irda_skb_cb *cb = (struct irda_skb_cb *) skb->cb;

        /*  
         * Insert MTT (min. turn time) and speed into skb, so that the
         * device driver knows which settings to use 
         */
        cb->magic = LAP_MAGIC;
        cb->mtt = self->mtt_required;
        cb->speed = self->speed;

        /* Reset */
        self->mtt_required = 0;
        
        /* 
         * Delay equals negotiated BOFs count, plus the number of BOFs to 
         * force the negotiated minimum turnaround time 
         */
        cb->xbofs = self->bofs_count+self->xbofs_delay;
        
        /* Reset XBOF's delay (used only for getting min turn time) */
        self->xbofs_delay = 0;
}

/*
 * Function irlap_queue_xmit (self, skb)
 *
 *    A little wrapper for dev_queue_xmit, so we can insert some common
 *    code into it.
 */
void irlap_queue_xmit(struct irlap_cb *self, struct sk_buff *skb)
{
        /* Some common init stuff */
        skb->dev = self->netdev;
        skb->h.raw = skb->nh.raw = skb->mac.raw = skb->data;
        skb->protocol = htons(ETH_P_IRDA);
        skb->priority = TC_PRIO_BESTEFFORT;

        irlap_insert_info(self, skb);

        dev_queue_xmit(skb);
}

/*
 * Function irlap_send_snrm_cmd (void)
 *
 *    Transmits a connect SNRM command frame
 */
void irlap_send_snrm_frame(struct irlap_cb *self, struct qos_info *qos) 
{
        struct sk_buff *skb;
        struct snrm_frame *frame;
        int ret;

        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);

        /* Allocate frame */
        skb = dev_alloc_skb(64);
        if (!skb)
                return;

        frame = (struct snrm_frame *) skb_put(skb, 2); 

        /* Insert connection address field */
        if (qos)
                frame->caddr = CMD_FRAME | CBROADCAST;
        else
                frame->caddr = CMD_FRAME | self->caddr;

        /* Insert control field */
        frame->control = SNRM_CMD | PF_BIT;
        
        /*
         *  If we are establishing a connection then insert QoS paramerters 
         */
        if (qos) {
                skb_put(skb, 9); /* 21 left */
                frame->saddr = cpu_to_le32(self->saddr);
                frame->daddr = cpu_to_le32(self->daddr);

                frame->ncaddr = self->caddr;
                                
                ret = irlap_insert_qos_negotiation_params(self, skb);
                if (ret < 0) {
                        dev_kfree_skb(skb);
                        return;
                }
        }
        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_recv_snrm_cmd (skb, info)
 *
 *    Received SNRM (Set Normal Response Mode) command frame
 *
 */
static void irlap_recv_snrm_cmd(struct irlap_cb *self, struct sk_buff *skb, 
                                struct irlap_info *info) 
{
        struct snrm_frame *frame;

        frame = (struct snrm_frame *) skb->data;
        
        if (skb->len >= sizeof(struct snrm_frame)) {
                /* Copy the new connection address */
                info->caddr = frame->ncaddr;

                /* Check if the new connection address is valid */
                if ((info->caddr == 0x00) || (info->caddr == 0xfe)) {
                        IRDA_DEBUG(3, __FUNCTION__ 
                              "(), invalid connection address!\n");
                        dev_kfree_skb(skb);
                        return;
                }
                
                /* Copy peer device address */
                info->daddr = le32_to_cpu(frame->saddr);
                info->saddr = le32_to_cpu(frame->daddr);
                
                /* Only accept if addressed directly to us */
                if (info->saddr != self->saddr) {
                        IRDA_DEBUG(2, __FUNCTION__ "(), not addressed to us!\n");
                        dev_kfree_skb(skb);
                        return;
                }
                irlap_do_event(self, RECV_SNRM_CMD, skb, info);
        } else
                /* Signal that this SNRM frame does not contain and I-field */
                irlap_do_event(self, RECV_SNRM_CMD, skb, NULL);
}

/*
 * Function irlap_send_ua_response_frame (qos)
 *
 *    Send UA (Unnumbered Acknowledgement) frame
 *
 */
void irlap_send_ua_response_frame(struct irlap_cb *self, struct qos_info *qos)
{
        struct sk_buff *skb;
        struct ua_frame *frame;
        int ret;
        
        IRDA_DEBUG(2, __FUNCTION__ "() <%ld>\n", jiffies);
        
        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);

        skb = NULL;

        /* Allocate frame */
        skb = dev_alloc_skb(64);
        if (!skb)
                return;

        frame = (struct ua_frame *) skb_put(skb, 10);
        
        /* Build UA response */
        frame->caddr = self->caddr;
        frame->control = UA_RSP | PF_BIT;

        frame->saddr = cpu_to_le32(self->saddr);
        frame->daddr = cpu_to_le32(self->daddr);

        /* Should we send QoS negotiation parameters? */
        if (qos) {
                ret = irlap_insert_qos_negotiation_params(self, skb);
                if (ret < 0) {
                        dev_kfree_skb(skb);
                        return;
                }
        }

        irlap_queue_xmit(self, skb);
}


/*
 * Function irlap_send_dm_frame (void)
 *
 *    Send disconnected mode (DM) frame
 *
 */
void irlap_send_dm_frame( struct irlap_cb *self)
{
        struct sk_buff *skb = NULL;
        __u8 *frame;
        
        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);

        skb = dev_alloc_skb(32);
        if (!skb)
                return;

        frame = skb_put( skb, 2);
        
        if (self->state == LAP_NDM)
                frame[0] = CBROADCAST;
        else
                frame[0] = self->caddr;

        frame[1] = DM_RSP | PF_BIT;

        irlap_queue_xmit(self, skb);    
}

/*
 * Function irlap_send_disc_frame (void)
 *
 *    Send disconnect (DISC) frame
 *
 */
void irlap_send_disc_frame(struct irlap_cb *self) 
{
        struct sk_buff *skb = NULL;
        __u8 *frame;
        
        IRDA_DEBUG(3, __FUNCTION__ "()\n");

        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);

        skb = dev_alloc_skb(16);
        if (!skb)
                return;

        frame = skb_put(skb, 2);
        
        frame[0] = self->caddr | CMD_FRAME;
        frame[1] = DISC_CMD | PF_BIT;

        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_send_discovery_xid_frame (S, s, command)
 *
 *    Build and transmit a XID (eXchange station IDentifier) discovery
 *    frame. 
 */
void irlap_send_discovery_xid_frame(struct irlap_cb *self, int S, __u8 s, 
                                    __u8 command, discovery_t *discovery) 
{
        struct sk_buff *skb = NULL;
        struct xid_frame *frame;
        __u32 bcast = BROADCAST;
        __u8 *info;

        IRDA_DEBUG(4, __FUNCTION__ "(), s=%d, S=%d, command=%d\n", s, S, 
                   command);

        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);
        ASSERT(discovery != NULL, return;);

        skb = dev_alloc_skb(64);
        if (!skb)
                return;

        skb_put(skb, 14);
        frame = (struct xid_frame *) skb->data;

        if (command) {
                frame->caddr = CBROADCAST | CMD_FRAME;
                frame->control =  XID_CMD | PF_BIT;
        } else {
                frame->caddr = CBROADCAST;
                frame->control =  XID_RSP | PF_BIT;
        }
        frame->ident = XID_FORMAT;

        frame->saddr = cpu_to_le32(self->saddr);

        if (command)
                frame->daddr = cpu_to_le32(bcast);
        else
                frame->daddr = cpu_to_le32(discovery->daddr);
        
        switch (S) {
        case 1:
                frame->flags = 0x00;
                break;
        case 6:
                frame->flags = 0x01;
                break;
        case 8:
                frame->flags = 0x02;
                break;
        case 16:
                frame->flags = 0x03;
                break;
        default:
                frame->flags = 0x02;
                break;
        }

        frame->slotnr = s; 
        frame->version = 0x00;

        /*  
         *  Provide info for final slot only in commands, and for all
         *  responses. Send the second byte of the hint only if the
         *  EXTENSION bit is set in the first byte.
         */
        if (!command || (frame->slotnr == 0xff)) {
                int len;

                if (discovery->hints.byte[0] & HINT_EXTENSION) {
                        info = skb_put(skb, 2);         
                        info[0] = discovery->hints.byte[0];
                        info[1] = discovery->hints.byte[1];
                } else {
                        info = skb_put(skb, 1);
                        info[0] = discovery->hints.byte[0];
                }
                info = skb_put(skb, 1);
                info[0] = discovery->charset;

                len = IRDA_MIN(discovery->name_len, skb_tailroom(skb));
                info = skb_put(skb, len);
                memcpy(info, discovery->nickname, len);
        } 
        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_recv_discovery_xid_rsp (skb, info)
 *
 *    Received a XID discovery response
 *
 */
static void irlap_recv_discovery_xid_rsp(struct irlap_cb *self, 
                                         struct sk_buff *skb, 
                                         struct irlap_info *info) 
{
        struct xid_frame *xid;
        discovery_t *discovery = NULL;
        __u8 *discovery_info;
        char *text;

        IRDA_DEBUG(4, __FUNCTION__ "()\n");

        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);

        xid = (struct xid_frame *) skb->data;

        info->daddr = le32_to_cpu(xid->saddr);
        info->saddr = le32_to_cpu(xid->daddr);

        /* Make sure frame is addressed to us */
        if ((info->saddr != self->saddr) && (info->saddr != BROADCAST)) {
                IRDA_DEBUG(0, __FUNCTION__ 
                           "(), frame is not addressed to us!\n");
                dev_kfree_skb(skb);
                return;
        }

        if ((discovery = kmalloc(sizeof(discovery_t), GFP_ATOMIC)) == NULL) {
                WARNING(__FUNCTION__ "(), kmalloc failed!\n");
                dev_kfree_skb(skb);
                return;
        }
        memset(discovery, 0, sizeof(discovery_t));

        discovery->daddr = info->daddr;
        discovery->saddr = self->saddr;
        discovery->timestamp = jiffies;

        IRDA_DEBUG(4, __FUNCTION__ "(), daddr=%08x\n", discovery->daddr);

        discovery_info = skb_pull(skb, sizeof(struct xid_frame));

        /* Get info returned from peer */
        discovery->hints.byte[0] = discovery_info[0];
        if (discovery_info[0] & HINT_EXTENSION) {
                IRDA_DEBUG(4, "EXTENSION\n");
                discovery->hints.byte[1] = discovery_info[1];
                discovery->charset = discovery_info[2];
                text = (char *) &discovery_info[3];
        } else {
                discovery->hints.byte[1] = 0;
                discovery->charset = discovery_info[1];
                text = (char *) &discovery_info[2];
        }
        /* 
         *  Terminate info string, should be safe since this is where the 
         *  FCS bytes resides.
         */
        skb->data[skb->len] = '\0'; 
        strncpy(discovery->nickname, text, NICKNAME_MAX_LEN);
        discovery->name_len = strlen(discovery->nickname);

        info->discovery = discovery;

        irlap_do_event(self, RECV_DISCOVERY_XID_RSP, skb, info);
}

/*
 * Function irlap_recv_discovery_xid_cmd (skb, info)
 *
 *    Received a XID discovery command
 *
 */
static void irlap_recv_discovery_xid_cmd(struct irlap_cb *self, 
                                         struct sk_buff *skb, 
                                         struct irlap_info *info) 
{
        struct xid_frame *xid;
        discovery_t *discovery = NULL;
        __u8 *discovery_info;
        char *text;

        xid = (struct xid_frame *) skb->data;

        info->daddr = le32_to_cpu(xid->saddr);
        info->saddr = le32_to_cpu(xid->daddr);

        /* Make sure frame is addressed to us */
        if ((info->saddr != self->saddr) && (info->saddr != BROADCAST)) {
                IRDA_DEBUG(0, __FUNCTION__ 
                           "(), frame is not addressed to us!\n");
                dev_kfree_skb(skb);
                return;
        }

        switch (xid->flags & 0x03) {
        case 0x00:
                info->S = 1;
                break;
        case 0x01:
                info->S = 6;
                break;
        case 0x02:
                info->S = 8;
                break;
        case 0x03:
                info->S = 16;
                break;
        default:
                /* Error!! */
                dev_kfree_skb(skb);
                return;
        }
        info->s = xid->slotnr;
        
        discovery_info = skb_pull(skb, sizeof(struct xid_frame));

        /* 
         *  Check if last frame 
         */
        if (info->s == 0xff) {
                /*
                 *  We now have some discovery info to deliver!
                 */
                discovery = kmalloc(sizeof(discovery_t), GFP_ATOMIC);
                if (!discovery) {
                        WARNING(__FUNCTION__ "(), unable to malloc!\n");
                        dev_kfree_skb(skb);
                        return;
                }
              
                discovery->daddr = info->daddr;
                discovery->saddr = self->saddr;
                discovery->timestamp = jiffies;

                discovery->hints.byte[0] = discovery_info[0];
                if (discovery_info[0] & HINT_EXTENSION) {
                        discovery->hints.byte[1] = discovery_info[1];
                        discovery->charset = discovery_info[2];
                        text = (char *) &discovery_info[3];
                } else {
                        discovery->hints.byte[1] = 0;
                        discovery->charset = discovery_info[1];
                        text = (char *) &discovery_info[2];
                }
                /* 
                 *  Terminate string, should be safe since this is where the 
                 *  FCS bytes resides.
                 */
                skb->data[skb->len] = '\0'; 
                strncpy(discovery->nickname, text, NICKNAME_MAX_LEN);
                discovery->name_len = strlen(discovery->nickname);

                info->discovery = discovery;
        } else
                info->discovery = NULL;
        
        irlap_do_event(self, RECV_DISCOVERY_XID_CMD, skb, info);
}

/*
 * Function irlap_send_rr_frame (self, command)
 *
 *    Build and transmit RR (Receive Ready) frame. Notice that it is currently
 *    only possible to send RR frames with the poll bit set.
 */
void irlap_send_rr_frame(struct irlap_cb *self, int command) 
{
        struct sk_buff *skb;
        __u8 *frame;

        skb = dev_alloc_skb(16);
        if (!skb)
                return;
        
        frame = skb_put(skb, 2);
        
        frame[0] = self->caddr;
        frame[0] |= (command) ? CMD_FRAME : 0;

        frame[1] = RR | PF_BIT | (self->vr << 5);

        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_send_rd_frame (self)
 *
 *    Request disconnect. Used by a secondary station to request the 
 *    disconnection of the link.
 */
void irlap_send_rd_frame(struct irlap_cb *self)
{
        struct sk_buff *skb;
        __u8 *frame;

        skb = dev_alloc_skb(16);
        if (!skb)
                return;
        
        frame = skb_put(skb, 2);
        
        frame[0] = self->caddr;
        frame[1] = RD_RSP | PF_BIT;

        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_recv_rr_frame (skb, info)
 *
 *    Received RR (Receive Ready) frame from peer station, no harm in
 *    making it inline since its called only from one single place
 *    (irlap_driver_rcv).
 */
static inline void irlap_recv_rr_frame(struct irlap_cb *self, 
                                       struct sk_buff *skb, 
                                       struct irlap_info *info, int command)
{
        info->nr = skb->data[1] >> 5;

        /* Check if this is a command or a response frame */
        if (command)
                irlap_do_event(self, RECV_RR_CMD, skb, info);
        else
                irlap_do_event(self, RECV_RR_RSP, skb, info);
}

void irlap_send_frmr_frame( struct irlap_cb *self, int command)
{
        struct sk_buff *skb = NULL;
        __u8 *frame;
        
        ASSERT( self != NULL, return;);
        ASSERT( self->magic == LAP_MAGIC, return;);

        skb = dev_alloc_skb( 32);
        if (!skb)
                return;

        frame = skb_put( skb, 2);
        
        frame[0] = self->caddr;
        frame[0] |= (command) ? CMD_FRAME : 0;

        frame[1]  = (self->vs << 1);
        frame[1] |= PF_BIT;
        frame[1] |= (self->vr << 5);

        frame[2] = 0;

        IRDA_DEBUG(4, __FUNCTION__ "(), vr=%d, %ld\n",self->vr, jiffies); 

        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_recv_rnr_frame (self, skb, info)
 *
 *    Received RNR (Receive Not Ready) frame from peer station
 *
 */
static void irlap_recv_rnr_frame(struct irlap_cb *self, struct sk_buff *skb, 
                                 struct irlap_info *info, int command) 
{
        info->nr = skb->data[1] >> 5;

        IRDA_DEBUG(4, __FUNCTION__ "(), nr=%d, %ld\n", info->nr, jiffies);

        if (command)
                irlap_do_event(self, RECV_RNR_CMD, skb, info);
        else
                irlap_do_event(self, RECV_RNR_RSP, skb, info);
}

static void irlap_recv_rej_frame(struct irlap_cb *self, struct sk_buff *skb, 
                                 struct irlap_info *info, int command)
{
        IRDA_DEBUG(0, __FUNCTION__ "()\n");

        info->nr = skb->data[1] >> 5;
        
        /* Check if this is a command or a response frame */
        if (command)
                irlap_do_event(self, RECV_REJ_CMD, skb, info);
        else
                irlap_do_event(self, RECV_REJ_RSP, skb, info);
}

static void irlap_recv_srej_frame(struct irlap_cb *self, struct sk_buff *skb, 
                                  struct irlap_info *info, int command)
{
        IRDA_DEBUG(0, __FUNCTION__ "()\n");

        info->nr = skb->data[1] >> 5;
        
        /* Check if this is a command or a response frame */
        if (command)
                irlap_do_event(self, RECV_SREJ_CMD, skb, info);
        else
                irlap_do_event(self, RECV_SREJ_RSP, skb, info);
}

static void irlap_recv_disc_frame(struct irlap_cb *self, struct sk_buff *skb, 
                                  struct irlap_info *info, int command)
{
        IRDA_DEBUG(0, __FUNCTION__ "()\n");

        /* Check if this is a command or a response frame */
        if (command)
                irlap_do_event(self, RECV_DISC_CMD, skb, info);
        else
                irlap_do_event(self, RECV_RD_RSP, skb, info);
}

/*
 * Function irlap_recv_ua_frame (skb, frame)
 *
 *    Received UA (Unnumbered Acknowledgement) frame
 *
 */
static inline void irlap_recv_ua_frame(struct irlap_cb *self, 
                                       struct sk_buff *skb, 
                                       struct irlap_info *info) 
{
        irlap_do_event(self, RECV_UA_RSP, skb, info);
}

/*
 * Function irlap_send_data_primary(self, skb)
 *
 *    Send I-frames as the primary station but without the poll bit set
 *
 */
void irlap_send_data_primary(struct irlap_cb *self, struct sk_buff *skb)
{
        struct sk_buff *tx_skb;

        if (skb->data[1] == I_FRAME) {

                /*  
                 *  Insert frame sequence number (Vs) in control field before
                 *  inserting into transmit window queue.
                 */
                skb->data[1] = I_FRAME | (self->vs << 1);
                
                /* Copy buffer */
                tx_skb = skb_clone(skb, GFP_ATOMIC);
                if (tx_skb == NULL) {
                        dev_kfree_skb(skb);
                        return;
                }
                
                /*
                 *  make sure the skb->sk accounting of memory usage is sane
                 */
                if (skb->sk != NULL)
                        skb_set_owner_w(tx_skb, skb->sk);
                
                /* 
                 *  Insert frame in store, in case of retransmissions 
                 */
                skb_queue_tail(&self->wx_list, skb);
                
                self->vs = (self->vs + 1) % 8;
                self->ack_required = FALSE;             
                self->window -= 1;

                irlap_send_i_frame( self, tx_skb, CMD_FRAME);
        } else {
                IRDA_DEBUG(4, __FUNCTION__ "(), sending unreliable frame\n");
                irlap_send_ui_frame(self, skb, self->caddr, CMD_FRAME);
                self->window -= 1;
        }
}
/*
 * Function irlap_send_data_primary_poll (self, skb)
 *
 *    Send I(nformation) frame as primary with poll bit set
 */
void irlap_send_data_primary_poll(struct irlap_cb *self, struct sk_buff *skb) 
{
        struct sk_buff *tx_skb;

        /* Is this reliable or unreliable data? */
        if (skb->data[1] == I_FRAME) {
                
                /*  
                 *  Insert frame sequence number (Vs) in control field before
                 *  inserting into transmit window queue.
                 */
                skb->data[1] = I_FRAME | (self->vs << 1);
                
                /* Copy buffer */
                tx_skb = skb_clone(skb, GFP_ATOMIC);
                if (tx_skb == NULL) {
                        dev_kfree_skb(skb);
                        return;
                }
                
                /*
                 *  make sure the skb->sk accounting of memory usage is sane
                 */
                if (skb->sk != NULL)
                        skb_set_owner_w(tx_skb, skb->sk);
                
                /* 
                 *  Insert frame in store, in case of retransmissions 
                 */
                skb_queue_tail(&self->wx_list, skb);
                
                /*  
                 *  Set poll bit if necessary. We do this to the copied
                 *  skb, since retransmitted need to set or clear the poll
                 *  bit depending on when they are sent.  
                 */
                /* Stop P timer */
                del_timer(&self->poll_timer);
                
                tx_skb->data[1] |= PF_BIT;
                
                self->vs = (self->vs + 1) % 8;
                self->ack_required = FALSE;
                self->window = self->window_size;

                irlap_start_final_timer(self, self->final_timeout);

                irlap_send_i_frame(self, tx_skb, CMD_FRAME);
        } else {
                IRDA_DEBUG(4, __FUNCTION__ "(), sending unreliable frame\n");

                del_timer(&self->poll_timer);

                if (self->ack_required) {
                        irlap_send_ui_frame(self, skb, self->caddr, CMD_FRAME);
                        irlap_send_rr_frame(self, CMD_FRAME);
                        self->ack_required = FALSE;
                } else {
                        skb->data[1] |= PF_BIT;
                        irlap_send_ui_frame(self, skb, self->caddr, CMD_FRAME);
                }
                self->window = self->window_size;
                irlap_start_final_timer(self, self->final_timeout);
        }
}

/*
 * Function irlap_send_data_secondary_final (self, skb)
 *
 *    Send I(nformation) frame as secondary with final bit set
 *
 */
void irlap_send_data_secondary_final(struct irlap_cb *self, 
                                     struct sk_buff *skb) 
{
        struct sk_buff *tx_skb = NULL;

        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);
        ASSERT(skb != NULL, return;);

        /* Is this reliable or unreliable data? */
        if (skb->data[1] == I_FRAME) {

                /*  
                 *  Insert frame sequence number (Vs) in control field before
                 *  inserting into transmit window queue.
                 */
                skb->data[1] = I_FRAME | (self->vs << 1);
                
                tx_skb = skb_clone(skb, GFP_ATOMIC);
                if (tx_skb == NULL) {
                        dev_kfree_skb(skb);
                        return;
                }               

                if (skb->sk != NULL)
                        skb_set_owner_w(tx_skb, skb->sk);
                
                /* Insert frame in store */
                skb_queue_tail(&self->wx_list, skb);
                
                tx_skb->data[1] |= PF_BIT;
                
                self->vs = (self->vs + 1) % 8; 
                self->window = self->window_size;
                self->ack_required = FALSE;
                
                irlap_start_wd_timer(self, self->wd_timeout);

                irlap_send_i_frame(self, tx_skb, RSP_FRAME); 
        } else {
                if (self->ack_required) {
                        irlap_send_ui_frame(self, skb, self->caddr, RSP_FRAME);
                        irlap_send_rr_frame(self, RSP_FRAME);
                        self->ack_required = FALSE;
                } else {
                        skb->data[1] |= PF_BIT;
                        irlap_send_ui_frame(self, skb, self->caddr, RSP_FRAME);
                }
                self->window = self->window_size;

                irlap_start_wd_timer(self, self->wd_timeout);
        }
}

/*
 * Function irlap_send_data_secondary (self, skb)
 *
 *    Send I(nformation) frame as secondary without final bit set
 *
 */
void irlap_send_data_secondary(struct irlap_cb *self, struct sk_buff *skb) 
{
        struct sk_buff *tx_skb = NULL;

        /* Is this reliable or unreliable data? */
        if (skb->data[1] == I_FRAME) {
                
                /*  
                 *  Insert frame sequence number (Vs) in control field before
                 *  inserting into transmit window queue.
                 */
                skb->data[1] = I_FRAME | (self->vs << 1);
                
                tx_skb = skb_clone(skb, GFP_ATOMIC);
                if (tx_skb == NULL) {
                        dev_kfree_skb(skb);
                        return;
                }               
                
                if (skb->sk != NULL)
                        skb_set_owner_w(tx_skb, skb->sk);
                
                /* Insert frame in store */
                skb_queue_tail(&self->wx_list, skb);
                
                self->vs = (self->vs + 1) % 8;
                self->ack_required = FALSE;             
                self->window -= 1;

                irlap_send_i_frame(self, tx_skb, RSP_FRAME); 
        } else {
                irlap_send_ui_frame(self, skb, self->caddr, RSP_FRAME);
                self->window -= 1;
        }
}

/*
 * Function irlap_resend_rejected_frames (nr)
 *
 *    Resend frames which has not been acknowledged. Should be safe to 
 *    traverse the list without locking it since this function will only be 
 *    called from interrupt context (BH)
 */
void irlap_resend_rejected_frames(struct irlap_cb *self, int command)
{
        struct sk_buff *tx_skb;
        struct sk_buff *skb;
        int count;

        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);

        /* Initialize variables */
        skb = tx_skb = NULL;

        count = skb_queue_len(&self->wx_list);

        /*  Resend unacknowledged frame(s) */
        skb = skb_peek(&self->wx_list);
        while (skb != NULL) {
                irlap_wait_min_turn_around(self, &self->qos_tx);

                /* We copy the skb to be retransmitted since we will have to 
                 * modify it. Cloning will confuse packet sniffers 
                 */
                /* tx_skb = skb_clone( skb, GFP_ATOMIC); */
                tx_skb = skb_copy(skb, GFP_ATOMIC);
                if (!tx_skb) {
                        IRDA_DEBUG(0, __FUNCTION__ "(), unable to copy\n");
                        return;
                }
                /* Unlink tx_skb from list */
                tx_skb->next = tx_skb->prev = NULL;
                tx_skb->list = NULL;

                /*
                 *  make sure the skb->sk accounting of memory usage is sane
                 */
                if (skb->sk != NULL)
                        skb_set_owner_w(tx_skb, skb->sk);

                /* Clear old Nr field + poll bit */
                tx_skb->data[1] &= 0x0f;

                /* 
                 *  Set poll bit on the last frame retransmitted
                 */
                if (count-- == 1)
                        tx_skb->data[1] |= PF_BIT; /* Set p/f bit */
                else
                        tx_skb->data[1] &= ~PF_BIT; /* Clear p/f bit */
                
                irlap_send_i_frame(self, tx_skb, command);

                /* 
                 *  If our skb is the last buffer in the list, then
                 *  we are finished, if not, move to the next sk-buffer
                 */
                if (skb == skb_peek_tail(&self->wx_list))
                        skb = NULL;
                else
                        skb = skb->next;
        }
#if 0 /* Not yet */
        /* 
         *  We can now fill the window with additinal data frames
         */
        while (skb_queue_len( &self->txq) > 0) {
                
                IRDA_DEBUG(0, __FUNCTION__ "(), sending additional frames!\n");
                if ((skb_queue_len( &self->txq) > 0) && 
                    (self->window > 0)) {
                        skb = skb_dequeue( &self->txq); 
                        ASSERT(skb != NULL, return;);

                        /*
                         *  If send window > 1 then send frame with pf 
                         *  bit cleared
                         */ 
                        if ((self->window > 1) && 
                            skb_queue_len(&self->txq) > 0) 
                        {
                                irlap_send_data_primary(self, skb);
                        } else {
                                irlap_send_data_primary_poll(self, skb);
                        }
                }
        }
#endif
}

void irlap_resend_rejected_frame(struct irlap_cb *self, int command)
{
        struct sk_buff *tx_skb;
        struct sk_buff *skb;

        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);

        /* Initialize variables */
        skb = tx_skb = NULL;

        /*  Resend unacknowledged frame(s) */
        skb = skb_peek(&self->wx_list);
        if (skb != NULL) {
                irlap_wait_min_turn_around(self, &self->qos_tx);

                /* We copy the skb to be retransmitted since we will have to 
                 * modify it. Cloning will confuse packet sniffers 
                 */
                /* tx_skb = skb_clone( skb, GFP_ATOMIC); */
                tx_skb = skb_copy(skb, GFP_ATOMIC);
                if (!tx_skb) {
                        IRDA_DEBUG(0, __FUNCTION__ "(), unable to copy\n");
                        return; 
                }
                /* Unlink tx_skb from list */
                tx_skb->next = tx_skb->prev = NULL;
                tx_skb->list = NULL;

                /*
                 *  make sure the skb->sk accounting of memory usage is sane
                 */
                if (skb->sk != NULL)
                        skb_set_owner_w(tx_skb, skb->sk);

                /* Clear old Nr field + poll bit */
                tx_skb->data[1] &= 0x0f;

                /*  Set poll/final bit */
                tx_skb->data[1] |= PF_BIT; /* Set p/f bit */
                
                irlap_send_i_frame(self, tx_skb, command);
        }
}

/*
 * Function irlap_send_ui_frame (self, skb, command)
 *
 *    Contruct and transmit an Unnumbered Information (UI) frame
 *
 */
void irlap_send_ui_frame(struct irlap_cb *self, struct sk_buff *skb, 
                         __u8 caddr, int command)
{
        IRDA_DEBUG(4, __FUNCTION__ "()\n");
        
        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);
        ASSERT(skb != NULL, return;);
        
        /* Insert connection address */
        skb->data[0] = caddr | ((command) ? CMD_FRAME : 0);

        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_send_i_frame (skb)
 *
 *    Contruct and transmit Information (I) frame
 */
void irlap_send_i_frame(struct irlap_cb *self, struct sk_buff *skb, 
                        int command) 
{
        /* Insert connection address */
        skb->data[0] = self->caddr;
        skb->data[0] |= (command) ? CMD_FRAME : 0;
        
        /* Insert next to receive (Vr) */
        skb->data[1] |= (self->vr << 5);  /* insert nr */

        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_recv_i_frame (skb, frame)
 *
 *    Receive and parse an I (Information) frame, no harm in making it inline
 *    since it's called only from one single place (irlap_driver_rcv).
 */
static inline void irlap_recv_i_frame(struct irlap_cb *self, 
                                      struct sk_buff *skb, 
                                      struct irlap_info *info, int command) 
{
        info->nr = skb->data[1] >> 5;          /* Next to receive */
        info->pf = skb->data[1] & PF_BIT;      /* Final bit */
        info->ns = (skb->data[1] >> 1) & 0x07; /* Next to send */

        /* Check if this is a command or a response frame */
        if (command)
                irlap_do_event(self, RECV_I_CMD, skb, info);
        else
                irlap_do_event(self, RECV_I_RSP, skb, info);
}

/*
 * Function irlap_recv_ui_frame (self, skb, info)
 *
 *    Receive and parse an Unnumbered Information (UI) frame
 *
 */
static void irlap_recv_ui_frame(struct irlap_cb *self, struct sk_buff *skb, 
                                struct irlap_info *info)
{
        IRDA_DEBUG( 4, __FUNCTION__ "()\n");

        info->pf = skb->data[1] & PF_BIT;      /* Final bit */

        irlap_do_event(self, RECV_UI_FRAME, skb, info);
}

/*
 * Function irlap_recv_frmr_frame (skb, frame)
 *
 *    Received Frame Reject response.
 *
 */
static void irlap_recv_frmr_frame(struct irlap_cb *self, struct sk_buff *skb, 
                                  struct irlap_info *info) 
{
        __u8 *frame;
        int w, x, y, z;

        IRDA_DEBUG(0, __FUNCTION__ "()\n");
        
        ASSERT(self != NULL, return;);
        ASSERT(self->magic == LAP_MAGIC, return;);
        ASSERT(skb != NULL, return;);
        ASSERT(info != NULL, return;);
        
        frame = skb->data;

        info->nr = frame[2] >> 5;          /* Next to receive */
        info->pf = frame[2] & PF_BIT;      /* Final bit */
        info->ns = (frame[2] >> 1) & 0x07; /* Next to send */

        w = frame[3] & 0x01;
        x = frame[3] & 0x02;
        y = frame[3] & 0x04;
        z = frame[3] & 0x08;
        
        if (w) {
                IRDA_DEBUG(0, "Rejected control field is undefined or not "
                      "implemented.\n");
        } 
        if (x) {
                IRDA_DEBUG(0, "Rejected control field was invalid because it "
                      "contained a non permitted I field.\n");
        }
        if (y) {
                IRDA_DEBUG(0, "Received I field exceeded the maximum negotiated "
                      "for the existing connection or exceeded the maximum "
                      "this station supports if no connection exists.\n");
        }
        if (z) {
                IRDA_DEBUG(0, "Rejected control field control field contained an "
                      "invalid Nr count.\n");
        }
        irlap_do_event(self, RECV_FRMR_RSP, skb, info);
}

/*
 * Function irlap_send_test_frame (self, daddr)
 *
 *    Send a test frame response
 *
 */
void irlap_send_test_frame(struct irlap_cb *self, __u8 caddr, __u32 daddr, 
                           struct sk_buff *cmd)
{
        struct sk_buff *skb;
        struct test_frame *frame;
        __u8 *info;

        skb = dev_alloc_skb(cmd->len+sizeof(struct test_frame));
        if (!skb)
                return;

        /* Broadcast frames must include saddr and daddr fields */
        if (caddr == CBROADCAST) {
                frame = (struct test_frame *) 
                        skb_put(skb, sizeof(struct test_frame));

                /* Insert the swapped addresses */
                frame->saddr = cpu_to_le32(self->saddr);
                frame->daddr = cpu_to_le32(daddr);
        } else
                frame = (struct test_frame *) skb_put(skb, LAP_ADDR_HEADER + LAP_CTRL_HEADER);

        frame->caddr = caddr;
        frame->control = TEST_RSP | PF_BIT;

        /* Copy info */
        info = skb_put(skb, cmd->len);
        memcpy(info, cmd->data, cmd->len);

        /* Return to sender */
        irlap_wait_min_turn_around(self, &self->qos_tx);
        irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_recv_test_frame (self, skb)
 *
 *    Receive a test frame
 *
 */
static void irlap_recv_test_frame(struct irlap_cb *self, struct sk_buff *skb, 
                                  struct irlap_info *info, int command)
{
        struct test_frame *frame;

        IRDA_DEBUG(2, __FUNCTION__ "()\n");
        
        frame = (struct test_frame *) skb->data;
                
        /* Broadcast frames must carry saddr and daddr fields */
        if (info->caddr == CBROADCAST) {
                if (skb->len < sizeof(struct test_frame)) {
                        IRDA_DEBUG(0, __FUNCTION__ 
                                   "() test frame to short!\n");
                        dev_kfree_skb(skb);
                        return;
                }
                
                /* Read and swap addresses */
                info->daddr = le32_to_cpu(frame->saddr);
                info->saddr = le32_to_cpu(frame->daddr);

                /* Make sure frame is addressed to us */
                if ((info->saddr != self->saddr) && 
                    (info->saddr != BROADCAST)) {
                        dev_kfree_skb(skb);
                        return;
                }
        }

        if (command)
                irlap_do_event(self, RECV_TEST_CMD, skb, info);
        else
                irlap_do_event(self, RECV_TEST_RSP, skb, info);
}

/*
 * Function irlap_driver_rcv (skb, netdev, ptype)
 *
 *    Called when a frame is received. Dispatches the right receive function 
 *    for processing of the frame.
 *
 */
int irlap_driver_rcv(struct sk_buff *skb, struct device *dev, 
                     struct packet_type *ptype)
{
        struct irlap_info info;
        struct irlap_cb *self;
        int command;
        __u8 control;
        
        /* FIXME: should we get our own field? */
        self = (struct irlap_cb *) dev->atalk_ptr;

        /* If the net device is down, then IrLAP is gone! */
        if (!self || self->magic != LAP_MAGIC) {
                dev_kfree_skb(skb);
                return -1;
        }

        /* Check if frame is large enough for parsing */
        if (skb->len < 2) {
                ERROR(__FUNCTION__ "(), frame to short!\n");
                dev_kfree_skb(skb);
                return -1;
        }
        
        command    = skb->data[0] & CMD_FRAME;
        info.caddr = skb->data[0] & CBROADCAST;
        
        info.pf      = skb->data[1] &  PF_BIT;
        info.control = skb->data[1] & ~PF_BIT; /* Mask away poll/final bit */

        control = info.control;

        /*  First we check if this frame has a valid connection address */
        if ((info.caddr != self->caddr) && (info.caddr != CBROADCAST)) {
                IRDA_DEBUG(0, __FUNCTION__ "(), wrong connection address!\n");
                dev_kfree_skb(skb);
                return 0;
        }
        /*  
         *  Optimize for the common case and check if the frame is an
         *  I(nformation) frame. Only I-frames have bit 0 set to 0
         */
        if (~control & 0x01) {