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irlap_frame.c

/*********************************************************************
 *
 * 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:   Wed Jan  5 08:59:04 2000
 * Modified by:   Dag Brattli <dagb@cs.uit.no>
 *
 *     Copyright (c) 1998-2000 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/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>

static void irlap_send_i_frame(struct irlap_cb *self, struct sk_buff *skb,
                         int command);

/*
 * 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->next_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;
      cb->next_xbofs = self->next_bofs;
      cb->xbofs_delay = self->xbofs_delay;

      /* Reset XBOF's delay (used only for getting min turn time) */
      self->xbofs_delay = 0;
      /* Put the correct xbofs value for the next packet */
      self->bofs_count = self->next_bofs;
}

/*
 * 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_reset_mac_header(skb);
      skb_reset_network_header(skb);
      skb_reset_transport_header(skb);
      skb->protocol = htons(ETH_P_IRDA);
      skb->priority = TC_PRIO_BESTEFFORT;

      irlap_insert_info(self, skb);

      if (unlikely(self->mode & IRDA_MODE_MONITOR)) {
            IRDA_DEBUG(3, "%s(): %s is in monitor mode\n", __FUNCTION__,
                     self->netdev->name);
            dev_kfree_skb(skb);
            return;
      }

      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 *tx_skb;
      struct snrm_frame *frame;
      int ret;

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

      /* Allocate frame */
      tx_skb = alloc_skb(sizeof(struct snrm_frame) +
                     IRLAP_NEGOCIATION_PARAMS_LEN,
                     GFP_ATOMIC);
      if (!tx_skb)
            return;

      frame = (struct snrm_frame *) skb_put(tx_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 parameters
       */
      if (qos) {
            skb_put(tx_skb, 9); /* 25 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, tx_skb);
            if (ret < 0) {
                  dev_kfree_skb(tx_skb);
                  return;
            }
      }
      irlap_queue_xmit(self, tx_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;

      if (pskb_may_pull(skb,sizeof(struct snrm_frame))) {
            frame = (struct snrm_frame *) skb->data;

            /* Copy the new connection address ignoring the C/R bit */
            info->caddr = frame->ncaddr & 0xFE;

            /* Check if the new connection address is valid */
            if ((info->caddr == 0x00) || (info->caddr == 0xfe)) {
                  IRDA_DEBUG(3, "%s(), invalid connection address!\n",
                           __FUNCTION__);
                  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, "%s(), not addressed to us!\n",
                           __FUNCTION__);
                  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 *tx_skb;
      struct ua_frame *frame;
      int ret;

      IRDA_DEBUG(2, "%s() <%ld>\n", __FUNCTION__, jiffies);

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

      /* Allocate frame */
      tx_skb = alloc_skb(sizeof(struct ua_frame) +
                     IRLAP_NEGOCIATION_PARAMS_LEN,
                     GFP_ATOMIC);
      if (!tx_skb)
            return;

      frame = (struct ua_frame *) skb_put(tx_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, tx_skb);
            if (ret < 0) {
                  dev_kfree_skb(tx_skb);
                  return;
            }
      }

      irlap_queue_xmit(self, tx_skb);
}


/*
 * Function irlap_send_dm_frame (void)
 *
 *    Send disconnected mode (DM) frame
 *
 */
void irlap_send_dm_frame( struct irlap_cb *self)
{
      struct sk_buff *tx_skb = NULL;
      struct dm_frame *frame;

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

      tx_skb = alloc_skb(sizeof(struct dm_frame), GFP_ATOMIC);
      if (!tx_skb)
            return;

      frame = (struct dm_frame *)skb_put(tx_skb, 2);

      if (self->state == LAP_NDM)
            frame->caddr = CBROADCAST;
      else
            frame->caddr = self->caddr;

      frame->control = DM_RSP | PF_BIT;

      irlap_queue_xmit(self, tx_skb);
}

/*
 * Function irlap_send_disc_frame (void)
 *
 *    Send disconnect (DISC) frame
 *
 */
void irlap_send_disc_frame(struct irlap_cb *self)
{
      struct sk_buff *tx_skb = NULL;
      struct disc_frame *frame;

      IRDA_DEBUG(3, "%s()\n", __FUNCTION__);

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

      tx_skb = alloc_skb(sizeof(struct disc_frame), GFP_ATOMIC);
      if (!tx_skb)
            return;

      frame = (struct disc_frame *)skb_put(tx_skb, 2);

      frame->caddr = self->caddr | CMD_FRAME;
      frame->control = DISC_CMD | PF_BIT;

      irlap_queue_xmit(self, tx_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 *tx_skb = NULL;
      struct xid_frame *frame;
      __u32 bcast = BROADCAST;
      __u8 *info;

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

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

      tx_skb = alloc_skb(sizeof(struct xid_frame) + IRLAP_DISCOVERY_INFO_LEN,
                     GFP_ATOMIC);
      if (!tx_skb)
            return;

      skb_put(tx_skb, 14);
      frame = (struct xid_frame *) tx_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->data.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->data.hints[0] & HINT_EXTENSION) {
                  info = skb_put(tx_skb, 2);
                  info[0] = discovery->data.hints[0];
                  info[1] = discovery->data.hints[1];
            } else {
                  info = skb_put(tx_skb, 1);
                  info[0] = discovery->data.hints[0];
            }
            info = skb_put(tx_skb, 1);
            info[0] = discovery->data.charset;

            len = IRDA_MIN(discovery->name_len, skb_tailroom(tx_skb));
            info = skb_put(tx_skb, len);
            memcpy(info, discovery->data.info, len);
      }
      irlap_queue_xmit(self, tx_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, "%s()\n", __FUNCTION__);

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

      if (!pskb_may_pull(skb, sizeof(struct xid_frame))) {
            IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
            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, "%s(), frame is not addressed to us!\n",
                     __FUNCTION__);
            return;
      }

      if ((discovery = kzalloc(sizeof(discovery_t), GFP_ATOMIC)) == NULL) {
            IRDA_WARNING("%s: kmalloc failed!\n", __FUNCTION__);
            return;
      }

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

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

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

      /* Get info returned from peer */
      discovery->data.hints[0] = discovery_info[0];
      if (discovery_info[0] & HINT_EXTENSION) {
            IRDA_DEBUG(4, "EXTENSION\n");
            discovery->data.hints[1] = discovery_info[1];
            discovery->data.charset = discovery_info[2];
            text = (char *) &discovery_info[3];
      } else {
            discovery->data.hints[1] = 0;
            discovery->data.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->data.info, text, NICKNAME_MAX_LEN);
      discovery->name_len = strlen(discovery->data.info);

      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;

      if (!pskb_may_pull(skb, sizeof(struct xid_frame))) {
            IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
            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, "%s(), frame is not addressed to us!\n",
                     __FUNCTION__);
            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!! */
            return;
      }
      info->s = xid->slotnr;

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

      /*
       *  Check if last frame
       */
      if (info->s == 0xff) {
            /* Check if things are sane at this point... */
            if((discovery_info == NULL) ||
               !pskb_may_pull(skb, 3)) {
                  IRDA_ERROR("%s: discovery frame too short!\n",
                           __FUNCTION__);
                  return;
            }

            /*
             *  We now have some discovery info to deliver!
             */
            discovery = kmalloc(sizeof(discovery_t), GFP_ATOMIC);
            if (!discovery) {
                  IRDA_WARNING("%s: unable to malloc!\n", __FUNCTION__);
                  return;
            }

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

            discovery->data.hints[0] = discovery_info[0];
            if (discovery_info[0] & HINT_EXTENSION) {
                  discovery->data.hints[1] = discovery_info[1];
                  discovery->data.charset = discovery_info[2];
                  text = (char *) &discovery_info[3];
            } else {
                  discovery->data.hints[1] = 0;
                  discovery->data.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->data.info, text, NICKNAME_MAX_LEN);
            discovery->name_len = strlen(discovery->data.info);

            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 *tx_skb;
      struct rr_frame *frame;

      tx_skb = alloc_skb(sizeof(struct rr_frame), GFP_ATOMIC);
      if (!tx_skb)
            return;

      frame = (struct rr_frame *)skb_put(tx_skb, 2);

      frame->caddr = self->caddr;
      frame->caddr |= (command) ? CMD_FRAME : 0;

      frame->control = RR | PF_BIT | (self->vr << 5);

      irlap_queue_xmit(self, tx_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 *tx_skb;
      struct rd_frame *frame;

      tx_skb = alloc_skb(sizeof(struct rd_frame), GFP_ATOMIC);
      if (!tx_skb)
            return;

      frame = (struct rd_frame *)skb_put(tx_skb, 2);

      frame->caddr = self->caddr;
      frame->caddr = RD_RSP | PF_BIT;

      irlap_queue_xmit(self, tx_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);
}

/*
 * 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, "%s(), nr=%d, %ld\n", __FUNCTION__, 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, "%s()\n", __FUNCTION__);

      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, "%s()\n", __FUNCTION__);

      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(2, "%s()\n", __FUNCTION__);

      /* 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);

            /*
             *  Insert frame in store, in case of retransmissions
             *  Increase skb reference count, see irlap_do_event()
             */
            skb_get(skb);
            skb_queue_tail(&self->wx_list, skb);

            /* Copy buffer */
            tx_skb = skb_clone(skb, GFP_ATOMIC);
            if (tx_skb == NULL) {
                  return;
            }

            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, "%s(), sending unreliable frame\n", __FUNCTION__);
            irlap_send_ui_frame(self, skb_get(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;
      int transmission_time;

      /* Stop P timer */
      del_timer(&self->poll_timer);

      /* 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);

            /*
             *  Insert frame in store, in case of retransmissions
             *  Increase skb reference count, see irlap_do_event()
             */
            skb_get(skb);
            skb_queue_tail(&self->wx_list, skb);

            /* Copy buffer */
            tx_skb = skb_clone(skb, GFP_ATOMIC);
            if (tx_skb == NULL) {
                  return;
            }

            /*
             *  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.
             */
            tx_skb->data[1] |= PF_BIT;

            self->vs = (self->vs + 1) % 8;
            self->ack_required = FALSE;

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

            if (self->ack_required) {
                  irlap_send_ui_frame(self, skb_get(skb), self->caddr, CMD_FRAME);
                  irlap_next_state(self, LAP_NRM_P);
                  irlap_send_rr_frame(self, CMD_FRAME);
                  self->ack_required = FALSE;
            } else {
                  skb->data[1] |= PF_BIT;
                  irlap_next_state(self, LAP_NRM_P);
                  irlap_send_ui_frame(self, skb_get(skb), self->caddr, CMD_FRAME);
            }
      }

      /* How much time we took for transmission of all frames.
       * We don't know, so let assume we used the full window. Jean II */
      transmission_time = self->final_timeout;

      /* Reset parameter so that we can fill next window */
      self->window = self->window_size;

#ifdef CONFIG_IRDA_DYNAMIC_WINDOW
      /* Remove what we have not used. Just do a prorata of the
       * bytes left in window to window capacity.
       * See max_line_capacities[][] in qos.c for details. Jean II */
      transmission_time -= (self->final_timeout * self->bytes_left
                        / self->line_capacity);
      IRDA_DEBUG(4, "%s() adjusting transmission_time : ft=%d, bl=%d, lc=%d -> tt=%d\n", __FUNCTION__, self->final_timeout, self->bytes_left, self->line_capacity, transmission_time);

      /* We are allowed to transmit a maximum number of bytes again. */
      self->bytes_left = self->line_capacity;
#endif /* CONFIG_IRDA_DYNAMIC_WINDOW */

      /*
       * The network layer has a intermediate buffer between IrLAP
       * and the IrDA driver which can contain 8 frames. So, even
       * though IrLAP is currently sending the *last* frame of the
       * tx-window, the driver most likely has only just started
       * sending the *first* frame of the same tx-window.
       * I.e. we are always at the very begining of or Tx window.
       * Now, we are supposed to set the final timer from the end
       * of our tx-window to let the other peer reply. So, we need
       * to add extra time to compensate for the fact that we
       * are really at the start of tx-window, otherwise the final timer
       * might expire before he can answer...
       * Jean II
       */
      irlap_start_final_timer(self, self->final_timeout + transmission_time);

      /*
       * The clever amongst you might ask why we do this adjustement
       * only here, and not in all the other cases in irlap_event.c.
       * In all those other case, we only send a very short management
       * frame (few bytes), so the adjustement would be lost in the
       * noise...
       * The exception of course is irlap_resend_rejected_frame().
       * Jean II */
}

/*
 * 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;

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

            /*
             *  Insert frame in store, in case of retransmissions
             *  Increase skb reference count, see irlap_do_event()
             */
            skb_get(skb);
            skb_queue_tail(&self->wx_list, skb);

            tx_skb = skb_clone(skb, GFP_ATOMIC);
            if (tx_skb == NULL) {
                  return;
            }

            tx_skb->data[1] |= PF_BIT;

            self->vs = (self->vs + 1) % 8;
            self->ack_required = FALSE;

            irlap_send_i_frame(self, tx_skb, RSP_FRAME);
      } else {
            if (self->ack_required) {
                  irlap_send_ui_frame(self, skb_get(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_get(skb), self->caddr, RSP_FRAME);
            }
      }

      self->window = self->window_size;
#ifdef CONFIG_IRDA_DYNAMIC_WINDOW
      /* We are allowed to transmit a maximum number of bytes again. */
      self->bytes_left = self->line_capacity;
#endif /* CONFIG_IRDA_DYNAMIC_WINDOW */

      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);

            /*
             *  Insert frame in store, in case of retransmissions
             *  Increase skb reference count, see irlap_do_event()
             */
            skb_get(skb);
            skb_queue_tail(&self->wx_list, skb);

            tx_skb = skb_clone(skb, GFP_ATOMIC);
            if (tx_skb == NULL) {
                  return;
            }

            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_get(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;

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

      /* Initialize variables */
      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, "%s(), unable to copy\n", __FUNCTION__);
                  return;
            }

            /* 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 additional data frames
       */
      while (!skb_queue_empty(&self->txq)) {

            IRDA_DEBUG(0, "%s(), sending additional frames!\n", __FUNCTION__);
            if (self->window > 0) {
                  skb = skb_dequeue( &self->txq);
                  IRDA_ASSERT(skb != NULL, return;);

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

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

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

      /*  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, "%s(), unable to copy\n", __FUNCTION__);
                  return;
            }

            /* 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, "%s()\n", __FUNCTION__);

      IRDA_ASSERT(self != NULL, return;);
      IRDA_ASSERT(self->magic == LAP_MAGIC, return;);
      IRDA_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
 */
static 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, "%s()\n", __FUNCTION__);

      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, "%s()\n", __FUNCTION__);

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

      if (!pskb_may_pull(skb, 4)) {
            IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
            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 *tx_skb;
      struct test_frame *frame;
      __u8 *info;

      tx_skb = alloc_skb(cmd->len + sizeof(struct test_frame), GFP_ATOMIC);
      if (!tx_skb)
            return;

      /* Broadcast frames must include saddr and daddr fields */
      if (caddr == CBROADCAST) {
            frame = (struct test_frame *)
                  skb_put(tx_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(tx_skb, LAP_ADDR_HEADER + LAP_CTRL_HEADER);

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

      /* Copy info */
      info = skb_put(tx_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, tx_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, "%s()\n", __FUNCTION__);

      if (!pskb_may_pull(skb, sizeof(*frame))) {
            IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
            return;
      }
      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, "%s() test frame too short!\n",
                           __FUNCTION__);
                  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)) {
                  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.
 *
 * Note on skb management :
 * After calling the higher layers of the IrDA stack, we always
 * kfree() the skb, which drop the reference count (and potentially
 * destroy it).
 * If a higher layer of the stack want to keep the skb around (to put
 * in a queue or pass it to the higher layer), it will need to use
 * skb_get() to keep a reference on it. This is usually done at the
 * LMP level in irlmp.c.
 * Jean II
 */
int irlap_driver_rcv(struct sk_buff *skb, struct net_device *dev,
                 struct packet_type *ptype, struct net_device *orig_dev)
{
      struct irlap_info info;
      struct irlap_cb *self;
      int command;
      __u8 control;

      if (dev->nd_net != &init_net)
            goto out;

      /* 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;
      }

      /* We are no longer an "old" protocol, so we need to handle
       * share and non linear skbs. This should never happen, so
       * we don't need to be clever about it. Jean II */
      if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
            IRDA_ERROR("%s: can't clone shared skb!\n", __FUNCTION__);
            dev_kfree_skb(skb);
            return -1;
      }

      /* Check if frame is large enough for parsing */
      if (!pskb_may_pull(skb, 2)) {
            IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
            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, "%s(), wrong connection address!\n",
                     __FUNCTION__);
            goto out;
      }
      /*
       *  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) {
            irlap_recv_i_frame(self, skb, &info, command);
            goto out;
      }
      /*
       *  We now check is the frame is an S(upervisory) frame. Only
       *  S-frames have bit 0 set to 1 and bit 1 set to 0
       */
      if (~control & 0x02) {
            /*
             *  Received S(upervisory) frame, check which frame type it is
             *  only the first nibble is of interest
             */
            switch (control & 0x0f) {
            case RR:
                  irlap_recv_rr_frame(self, skb, &info, command);
                  break;
            case RNR:
                  irlap_recv_rnr_frame(self, skb, &info, command);
                  break;
            case REJ:
                  irlap_recv_rej_frame(self, skb, &info, command);
                  break;
            case SREJ:
                  irlap_recv_srej_frame(self, skb, &info, command);
                  break;
            default:
                  IRDA_WARNING("%s: Unknown S-frame %02x received!\n",
                        __FUNCTION__, info.control);
                  break;
            }
            goto out;
      }
      /*
       *  This must be a C(ontrol) frame
       */
      switch (control) {
      case XID_RSP:
            irlap_recv_discovery_xid_rsp(self, skb, &info);
            break;
      case XID_CMD:
            irlap_recv_discovery_xid_cmd(self, skb, &info);
            break;
      case SNRM_CMD:
            irlap_recv_snrm_cmd(self, skb, &info);
            break;
      case DM_RSP:
            irlap_do_event(self, RECV_DM_RSP, skb, &info);
            break;
      case DISC_CMD: /* And RD_RSP since they have the same value */
            irlap_recv_disc_frame(self, skb, &info, command);
            break;
      case TEST_CMD:
            irlap_recv_test_frame(self, skb, &info, command);
            break;
      case UA_RSP:
            irlap_recv_ua_frame(self, skb, &info);
            break;
      case FRMR_RSP:
            irlap_recv_frmr_frame(self, skb, &info);
            break;
      case UI_FRAME:
            irlap_recv_ui_frame(self, skb, &info);
            break;
      default:
            IRDA_WARNING("%s: Unknown frame %02x received!\n",
                        __FUNCTION__, info.control);
            break;
      }
out:
      /* Always drop our reference on the skb */
      dev_kfree_skb(skb);
      return 0;
}

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