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rx.c

/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007 Johannes Berg <johannes@sipsolutions.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rcupdate.h>
#include <net/mac80211.h>
#include <net/ieee80211_radiotap.h>

#include "ieee80211_i.h"
#include "ieee80211_led.h"
#include "wep.h"
#include "wpa.h"
#include "tkip.h"
#include "wme.h"

/*
 * monitor mode reception
 *
 * This function cleans up the SKB, i.e. it removes all the stuff
 * only useful for monitoring.
 */
static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
                                 struct sk_buff *skb,
                                 int rtap_len)
{
      skb_pull(skb, rtap_len);

      if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) {
            if (likely(skb->len > FCS_LEN))
                  skb_trim(skb, skb->len - FCS_LEN);
            else {
                  /* driver bug */
                  WARN_ON(1);
                  dev_kfree_skb(skb);
                  skb = NULL;
            }
      }

      return skb;
}

static inline int should_drop_frame(struct ieee80211_rx_status *status,
                            struct sk_buff *skb,
                            int present_fcs_len,
                            int radiotap_len)
{
      struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

      if (status->flag & (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
            return 1;
      if (unlikely(skb->len < 16 + present_fcs_len + radiotap_len))
            return 1;
      if ((hdr->frame_control & cpu_to_le16(IEEE80211_FCTL_FTYPE)) ==
                  cpu_to_le16(IEEE80211_FTYPE_CTL))
            return 1;
      return 0;
}

/*
 * This function copies a received frame to all monitor interfaces and
 * returns a cleaned-up SKB that no longer includes the FCS nor the
 * radiotap header the driver might have added.
 */
static struct sk_buff *
ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
                 struct ieee80211_rx_status *status)
{
      struct ieee80211_sub_if_data *sdata;
      struct ieee80211_rate *rate;
      int needed_headroom = 0;
      struct ieee80211_rtap_hdr {
            struct ieee80211_radiotap_header hdr;
            u8 flags;
            u8 rate;
            __le16 chan_freq;
            __le16 chan_flags;
            u8 antsignal;
            u8 padding_for_rxflags;
            __le16 rx_flags;
      } __attribute__ ((packed)) *rthdr;
      struct sk_buff *skb, *skb2;
      struct net_device *prev_dev = NULL;
      int present_fcs_len = 0;
      int rtap_len = 0;

      /*
       * First, we may need to make a copy of the skb because
       *  (1) we need to modify it for radiotap (if not present), and
       *  (2) the other RX handlers will modify the skb we got.
       *
       * We don't need to, of course, if we aren't going to return
       * the SKB because it has a bad FCS/PLCP checksum.
       */
      if (status->flag & RX_FLAG_RADIOTAP)
            rtap_len = ieee80211_get_radiotap_len(origskb->data);
      else
            needed_headroom = sizeof(*rthdr);

      if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
            present_fcs_len = FCS_LEN;

      if (!local->monitors) {
            if (should_drop_frame(status, origskb, present_fcs_len,
                              rtap_len)) {
                  dev_kfree_skb(origskb);
                  return NULL;
            }

            return remove_monitor_info(local, origskb, rtap_len);
      }

      if (should_drop_frame(status, origskb, present_fcs_len, rtap_len)) {
            /* only need to expand headroom if necessary */
            skb = origskb;
            origskb = NULL;

            /*
             * This shouldn't trigger often because most devices have an
             * RX header they pull before we get here, and that should
             * be big enough for our radiotap information. We should
             * probably export the length to drivers so that we can have
             * them allocate enough headroom to start with.
             */
            if (skb_headroom(skb) < needed_headroom &&
                pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC)) {
                  dev_kfree_skb(skb);
                  return NULL;
            }
      } else {
            /*
             * Need to make a copy and possibly remove radiotap header
             * and FCS from the original.
             */
            skb = skb_copy_expand(origskb, needed_headroom, 0, GFP_ATOMIC);

            origskb = remove_monitor_info(local, origskb, rtap_len);

            if (!skb)
                  return origskb;
      }

      /* if necessary, prepend radiotap information */
      if (!(status->flag & RX_FLAG_RADIOTAP)) {
            rthdr = (void *) skb_push(skb, sizeof(*rthdr));
            memset(rthdr, 0, sizeof(*rthdr));
            rthdr->hdr.it_len = cpu_to_le16(sizeof(*rthdr));
            rthdr->hdr.it_present =
                  cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
                            (1 << IEEE80211_RADIOTAP_RATE) |
                            (1 << IEEE80211_RADIOTAP_CHANNEL) |
                            (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL) |
                            (1 << IEEE80211_RADIOTAP_RX_FLAGS));
            rthdr->flags = local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS ?
                         IEEE80211_RADIOTAP_F_FCS : 0;

            /* FIXME: when radiotap gets a 'bad PLCP' flag use it here */
            rthdr->rx_flags = 0;
            if (status->flag &
                (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
                  rthdr->rx_flags |=
                        cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADFCS);

            rate = ieee80211_get_rate(local, status->phymode,
                                status->rate);
            if (rate)
                  rthdr->rate = rate->rate / 5;

            rthdr->chan_freq = cpu_to_le16(status->freq);

            if (status->phymode == MODE_IEEE80211A)
                  rthdr->chan_flags =
                        cpu_to_le16(IEEE80211_CHAN_OFDM |
                                  IEEE80211_CHAN_5GHZ);
            else
                  rthdr->chan_flags =
                        cpu_to_le16(IEEE80211_CHAN_DYN |
                                  IEEE80211_CHAN_2GHZ);

            rthdr->antsignal = status->ssi;
      }

      skb_set_mac_header(skb, 0);
      skb->ip_summed = CHECKSUM_UNNECESSARY;
      skb->pkt_type = PACKET_OTHERHOST;
      skb->protocol = htons(ETH_P_802_2);

      list_for_each_entry_rcu(sdata, &local->interfaces, list) {
            if (!netif_running(sdata->dev))
                  continue;

            if (sdata->type != IEEE80211_IF_TYPE_MNTR)
                  continue;

            if (prev_dev) {
                  skb2 = skb_clone(skb, GFP_ATOMIC);
                  if (skb2) {
                        skb2->dev = prev_dev;
                        netif_rx(skb2);
                  }
            }

            prev_dev = sdata->dev;
            sdata->dev->stats.rx_packets++;
            sdata->dev->stats.rx_bytes += skb->len;
      }

      if (prev_dev) {
            skb->dev = prev_dev;
            netif_rx(skb);
      } else
            dev_kfree_skb(skb);

      return origskb;
}


/* pre-rx handlers
 *
 * these don't have dev/sdata fields in the rx data
 * The sta value should also not be used because it may
 * be NULL even though a STA (in IBSS mode) will be added.
 */

static ieee80211_txrx_result
ieee80211_rx_h_parse_qos(struct ieee80211_txrx_data *rx)
{
      u8 *data = rx->skb->data;
      int tid;

      /* does the frame have a qos control field? */
      if (WLAN_FC_IS_QOS_DATA(rx->fc)) {
            u8 *qc = data + ieee80211_get_hdrlen(rx->fc) - QOS_CONTROL_LEN;
            /* frame has qos control */
            tid = qc[0] & QOS_CONTROL_TID_MASK;
      } else {
            if (unlikely((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_MGMT)) {
                  /* Separate TID for management frames */
                  tid = NUM_RX_DATA_QUEUES - 1;
            } else {
                  /* no qos control present */
                  tid = 0; /* 802.1d - Best Effort */
            }
      }

      I802_DEBUG_INC(rx->local->wme_rx_queue[tid]);
      /* only a debug counter, sta might not be assigned properly yet */
      if (rx->sta)
            I802_DEBUG_INC(rx->sta->wme_rx_queue[tid]);

      rx->u.rx.queue = tid;
      /* Set skb->priority to 1d tag if highest order bit of TID is not set.
       * For now, set skb->priority to 0 for other cases. */
      rx->skb->priority = (tid > 7) ? 0 : tid;

      return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_load_stats(struct ieee80211_txrx_data *rx)
{
      struct ieee80211_local *local = rx->local;
      struct sk_buff *skb = rx->skb;
      struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
      u32 load = 0, hdrtime;
      struct ieee80211_rate *rate;
      struct ieee80211_hw_mode *mode = local->hw.conf.mode;
      int i;

      /* Estimate total channel use caused by this frame */

      if (unlikely(mode->num_rates < 0))
            return TXRX_CONTINUE;

      rate = &mode->rates[0];
      for (i = 0; i < mode->num_rates; i++) {
            if (mode->rates[i].val == rx->u.rx.status->rate) {
                  rate = &mode->rates[i];
                  break;
            }
      }

      /* 1 bit at 1 Mbit/s takes 1 usec; in channel_use values,
       * 1 usec = 1/8 * (1080 / 10) = 13.5 */

      if (mode->mode == MODE_IEEE80211A ||
          (mode->mode == MODE_IEEE80211G &&
           rate->flags & IEEE80211_RATE_ERP))
            hdrtime = CHAN_UTIL_HDR_SHORT;
      else
            hdrtime = CHAN_UTIL_HDR_LONG;

      load = hdrtime;
      if (!is_multicast_ether_addr(hdr->addr1))
            load += hdrtime;

      load += skb->len * rate->rate_inv;

      /* Divide channel_use by 8 to avoid wrapping around the counter */
      load >>= CHAN_UTIL_SHIFT;
      local->channel_use_raw += load;
      rx->u.rx.load = load;

      return TXRX_CONTINUE;
}

ieee80211_rx_handler ieee80211_rx_pre_handlers[] =
{
      ieee80211_rx_h_parse_qos,
      ieee80211_rx_h_load_stats,
      NULL
};

/* rx handlers */

static ieee80211_txrx_result
ieee80211_rx_h_if_stats(struct ieee80211_txrx_data *rx)
{
      if (rx->sta)
            rx->sta->channel_use_raw += rx->u.rx.load;
      rx->sdata->channel_use_raw += rx->u.rx.load;
      return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_passive_scan(struct ieee80211_txrx_data *rx)
{
      struct ieee80211_local *local = rx->local;
      struct sk_buff *skb = rx->skb;

      if (unlikely(local->sta_scanning != 0)) {
            ieee80211_sta_rx_scan(rx->dev, skb, rx->u.rx.status);
            return TXRX_QUEUED;
      }

      if (unlikely(rx->flags & IEEE80211_TXRXD_RXIN_SCAN)) {
            /* scanning finished during invoking of handlers */
            I802_DEBUG_INC(local->rx_handlers_drop_passive_scan);
            return TXRX_DROP;
      }

      return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_check(struct ieee80211_txrx_data *rx)
{
      struct ieee80211_hdr *hdr;
      hdr = (struct ieee80211_hdr *) rx->skb->data;

      /* Drop duplicate 802.11 retransmissions (IEEE 802.11 Chap. 9.2.9) */
      if (rx->sta && !is_multicast_ether_addr(hdr->addr1)) {
            if (unlikely(rx->fc & IEEE80211_FCTL_RETRY &&
                       rx->sta->last_seq_ctrl[rx->u.rx.queue] ==
                       hdr->seq_ctrl)) {
                  if (rx->flags & IEEE80211_TXRXD_RXRA_MATCH) {
                        rx->local->dot11FrameDuplicateCount++;
                        rx->sta->num_duplicates++;
                  }
                  return TXRX_DROP;
            } else
                  rx->sta->last_seq_ctrl[rx->u.rx.queue] = hdr->seq_ctrl;
      }

      if (unlikely(rx->skb->len < 16)) {
            I802_DEBUG_INC(rx->local->rx_handlers_drop_short);
            return TXRX_DROP;
      }

      if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
            rx->skb->pkt_type = PACKET_OTHERHOST;
      else if (compare_ether_addr(rx->dev->dev_addr, hdr->addr1) == 0)
            rx->skb->pkt_type = PACKET_HOST;
      else if (is_multicast_ether_addr(hdr->addr1)) {
            if (is_broadcast_ether_addr(hdr->addr1))
                  rx->skb->pkt_type = PACKET_BROADCAST;
            else
                  rx->skb->pkt_type = PACKET_MULTICAST;
      } else
            rx->skb->pkt_type = PACKET_OTHERHOST;

      /* Drop disallowed frame classes based on STA auth/assoc state;
       * IEEE 802.11, Chap 5.5.
       *
       * 80211.o does filtering only based on association state, i.e., it
       * drops Class 3 frames from not associated stations. hostapd sends
       * deauth/disassoc frames when needed. In addition, hostapd is
       * responsible for filtering on both auth and assoc states.
       */
      if (unlikely(((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA ||
                  ((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_CTL &&
                   (rx->fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)) &&
                 rx->sdata->type != IEEE80211_IF_TYPE_IBSS &&
                 (!rx->sta || !(rx->sta->flags & WLAN_STA_ASSOC)))) {
            if ((!(rx->fc & IEEE80211_FCTL_FROMDS) &&
                 !(rx->fc & IEEE80211_FCTL_TODS) &&
                 (rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA)
                || !(rx->flags & IEEE80211_TXRXD_RXRA_MATCH)) {
                  /* Drop IBSS frames and frames for other hosts
                   * silently. */
                  return TXRX_DROP;
            }

            return TXRX_DROP;
      }

      return TXRX_CONTINUE;
}


static ieee80211_txrx_result
ieee80211_rx_h_decrypt(struct ieee80211_txrx_data *rx)
{
      struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
      int keyidx;
      int hdrlen;
      ieee80211_txrx_result result = TXRX_DROP;
      struct ieee80211_key *stakey = NULL;

      /*
       * Key selection 101
       *
       * There are three types of keys:
       *  - GTK (group keys)
       *  - PTK (pairwise keys)
       *  - STK (station-to-station pairwise keys)
       *
       * When selecting a key, we have to distinguish between multicast
       * (including broadcast) and unicast frames, the latter can only
       * use PTKs and STKs while the former always use GTKs. Unless, of
       * course, actual WEP keys ("pre-RSNA") are used, then unicast
       * frames can also use key indizes like GTKs. Hence, if we don't
       * have a PTK/STK we check the key index for a WEP key.
       *
       * Note that in a regular BSS, multicast frames are sent by the
       * AP only, associated stations unicast the frame to the AP first
       * which then multicasts it on their behalf.
       *
       * There is also a slight problem in IBSS mode: GTKs are negotiated
       * with each station, that is something we don't currently handle.
       * The spec seems to expect that one negotiates the same key with
       * every station but there's no such requirement; VLANs could be
       * possible.
       */

      if (!(rx->fc & IEEE80211_FCTL_PROTECTED))
            return TXRX_CONTINUE;

      /*
       * No point in finding a key and decrypting if the frame is neither
       * addressed to us nor a multicast frame.
       */
      if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
            return TXRX_CONTINUE;

      if (rx->sta)
            stakey = rcu_dereference(rx->sta->key);

      if (!is_multicast_ether_addr(hdr->addr1) && stakey) {
            rx->key = stakey;
      } else {
            /*
             * The device doesn't give us the IV so we won't be
             * able to look up the key. That's ok though, we
             * don't need to decrypt the frame, we just won't
             * be able to keep statistics accurate.
             * Except for key threshold notifications, should
             * we somehow allow the driver to tell us which key
             * the hardware used if this flag is set?
             */
            if ((rx->u.rx.status->flag & RX_FLAG_DECRYPTED) &&
                (rx->u.rx.status->flag & RX_FLAG_IV_STRIPPED))
                  return TXRX_CONTINUE;

            hdrlen = ieee80211_get_hdrlen(rx->fc);

            if (rx->skb->len < 8 + hdrlen)
                  return TXRX_DROP; /* TODO: count this? */

            /*
             * no need to call ieee80211_wep_get_keyidx,
             * it verifies a bunch of things we've done already
             */
            keyidx = rx->skb->data[hdrlen + 3] >> 6;

            rx->key = rcu_dereference(rx->sdata->keys[keyidx]);

            /*
             * RSNA-protected unicast frames should always be sent with
             * pairwise or station-to-station keys, but for WEP we allow
             * using a key index as well.
             */
            if (rx->key && rx->key->conf.alg != ALG_WEP &&
                !is_multicast_ether_addr(hdr->addr1))
                  rx->key = NULL;
      }

      if (rx->key) {
            rx->key->tx_rx_count++;
            /* TODO: add threshold stuff again */
      } else {
#ifdef CONFIG_MAC80211_DEBUG
            if (net_ratelimit())
                  printk(KERN_DEBUG "%s: RX protected frame,"
                         " but have no key\n", rx->dev->name);
#endif /* CONFIG_MAC80211_DEBUG */
            return TXRX_DROP;
      }

      /* Check for weak IVs if possible */
      if (rx->sta && rx->key->conf.alg == ALG_WEP &&
          ((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA) &&
          (!(rx->u.rx.status->flag & RX_FLAG_IV_STRIPPED) ||
           !(rx->u.rx.status->flag & RX_FLAG_DECRYPTED)) &&
          ieee80211_wep_is_weak_iv(rx->skb, rx->key))
            rx->sta->wep_weak_iv_count++;

      switch (rx->key->conf.alg) {
      case ALG_WEP:
            result = ieee80211_crypto_wep_decrypt(rx);
            break;
      case ALG_TKIP:
            result = ieee80211_crypto_tkip_decrypt(rx);
            break;
      case ALG_CCMP:
            result = ieee80211_crypto_ccmp_decrypt(rx);
            break;
      }

      /* either the frame has been decrypted or will be dropped */
      rx->u.rx.status->flag |= RX_FLAG_DECRYPTED;

      return result;
}

static void ap_sta_ps_start(struct net_device *dev, struct sta_info *sta)
{
      struct ieee80211_sub_if_data *sdata;
      DECLARE_MAC_BUF(mac);

      sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);

      if (sdata->bss)
            atomic_inc(&sdata->bss->num_sta_ps);
      sta->flags |= WLAN_STA_PS;
      sta->pspoll = 0;
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
      printk(KERN_DEBUG "%s: STA %s aid %d enters power save mode\n",
             dev->name, print_mac(mac, sta->addr), sta->aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
}

static int ap_sta_ps_end(struct net_device *dev, struct sta_info *sta)
{
      struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
      struct sk_buff *skb;
      int sent = 0;
      struct ieee80211_sub_if_data *sdata;
      struct ieee80211_tx_packet_data *pkt_data;
      DECLARE_MAC_BUF(mac);

      sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
      if (sdata->bss)
            atomic_dec(&sdata->bss->num_sta_ps);
      sta->flags &= ~(WLAN_STA_PS | WLAN_STA_TIM);
      sta->pspoll = 0;
      if (!skb_queue_empty(&sta->ps_tx_buf)) {
            if (local->ops->set_tim)
                  local->ops->set_tim(local_to_hw(local), sta->aid, 0);
            if (sdata->bss)
                  bss_tim_clear(local, sdata->bss, sta->aid);
      }
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
      printk(KERN_DEBUG "%s: STA %s aid %d exits power save mode\n",
             dev->name, print_mac(mac, sta->addr), sta->aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
      /* Send all buffered frames to the station */
      while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL) {
            pkt_data = (struct ieee80211_tx_packet_data *) skb->cb;
            sent++;
            pkt_data->flags |= IEEE80211_TXPD_REQUEUE;
            dev_queue_xmit(skb);
      }
      while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
            pkt_data = (struct ieee80211_tx_packet_data *) skb->cb;
            local->total_ps_buffered--;
            sent++;
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
            printk(KERN_DEBUG "%s: STA %s aid %d send PS frame "
                   "since STA not sleeping anymore\n", dev->name,
                   print_mac(mac, sta->addr), sta->aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
            pkt_data->flags |= IEEE80211_TXPD_REQUEUE;
            dev_queue_xmit(skb);
      }

      return sent;
}

static ieee80211_txrx_result
ieee80211_rx_h_sta_process(struct ieee80211_txrx_data *rx)
{
      struct sta_info *sta = rx->sta;
      struct net_device *dev = rx->dev;
      struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;

      if (!sta)
            return TXRX_CONTINUE;

      /* Update last_rx only for IBSS packets which are for the current
       * BSSID to avoid keeping the current IBSS network alive in cases where
       * other STAs are using different BSSID. */
      if (rx->sdata->type == IEEE80211_IF_TYPE_IBSS) {
            u8 *bssid = ieee80211_get_bssid(hdr, rx->skb->len);
            if (compare_ether_addr(bssid, rx->sdata->u.sta.bssid) == 0)
                  sta->last_rx = jiffies;
      } else
      if (!is_multicast_ether_addr(hdr->addr1) ||
          rx->sdata->type == IEEE80211_IF_TYPE_STA) {
            /* Update last_rx only for unicast frames in order to prevent
             * the Probe Request frames (the only broadcast frames from a
             * STA in infrastructure mode) from keeping a connection alive.
             */
            sta->last_rx = jiffies;
      }

      if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
            return TXRX_CONTINUE;

      sta->rx_fragments++;
      sta->rx_bytes += rx->skb->len;
      sta->last_rssi = rx->u.rx.status->ssi;
      sta->last_signal = rx->u.rx.status->signal;
      sta->last_noise = rx->u.rx.status->noise;

      if (!(rx->fc & IEEE80211_FCTL_MOREFRAGS)) {
            /* Change STA power saving mode only in the end of a frame
             * exchange sequence */
            if ((sta->flags & WLAN_STA_PS) && !(rx->fc & IEEE80211_FCTL_PM))
                  rx->u.rx.sent_ps_buffered += ap_sta_ps_end(dev, sta);
            else if (!(sta->flags & WLAN_STA_PS) &&
                   (rx->fc & IEEE80211_FCTL_PM))
                  ap_sta_ps_start(dev, sta);
      }

      /* Drop data::nullfunc frames silently, since they are used only to
       * control station power saving mode. */
      if ((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
          (rx->fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_NULLFUNC) {
            I802_DEBUG_INC(rx->local->rx_handlers_drop_nullfunc);
            /* Update counter and free packet here to avoid counting this
             * as a dropped packed. */
            sta->rx_packets++;
            dev_kfree_skb(rx->skb);
            return TXRX_QUEUED;
      }

      return TXRX_CONTINUE;
} /* ieee80211_rx_h_sta_process */

static inline struct ieee80211_fragment_entry *
ieee80211_reassemble_add(struct ieee80211_sub_if_data *sdata,
                   unsigned int frag, unsigned int seq, int rx_queue,
                   struct sk_buff **skb)
{
      struct ieee80211_fragment_entry *entry;
      int idx;

      idx = sdata->fragment_next;
      entry = &sdata->fragments[sdata->fragment_next++];
      if (sdata->fragment_next >= IEEE80211_FRAGMENT_MAX)
            sdata->fragment_next = 0;

      if (!skb_queue_empty(&entry->skb_list)) {
#ifdef CONFIG_MAC80211_DEBUG
            struct ieee80211_hdr *hdr =
                  (struct ieee80211_hdr *) entry->skb_list.next->data;
            DECLARE_MAC_BUF(mac);
            DECLARE_MAC_BUF(mac2);
            printk(KERN_DEBUG "%s: RX reassembly removed oldest "
                   "fragment entry (idx=%d age=%lu seq=%d last_frag=%d "
                   "addr1=%s addr2=%s\n",
                   sdata->dev->name, idx,
                   jiffies - entry->first_frag_time, entry->seq,
                   entry->last_frag, print_mac(mac, hdr->addr1),
                   print_mac(mac2, hdr->addr2));
#endif /* CONFIG_MAC80211_DEBUG */
            __skb_queue_purge(&entry->skb_list);
      }

      __skb_queue_tail(&entry->skb_list, *skb); /* no need for locking */
      *skb = NULL;
      entry->first_frag_time = jiffies;
      entry->seq = seq;
      entry->rx_queue = rx_queue;
      entry->last_frag = frag;
      entry->ccmp = 0;
      entry->extra_len = 0;

      return entry;
}

static inline struct ieee80211_fragment_entry *
ieee80211_reassemble_find(struct ieee80211_sub_if_data *sdata,
                    u16 fc, unsigned int frag, unsigned int seq,
                    int rx_queue, struct ieee80211_hdr *hdr)
{
      struct ieee80211_fragment_entry *entry;
      int i, idx;

      idx = sdata->fragment_next;
      for (i = 0; i < IEEE80211_FRAGMENT_MAX; i++) {
            struct ieee80211_hdr *f_hdr;
            u16 f_fc;

            idx--;
            if (idx < 0)
                  idx = IEEE80211_FRAGMENT_MAX - 1;

            entry = &sdata->fragments[idx];
            if (skb_queue_empty(&entry->skb_list) || entry->seq != seq ||
                entry->rx_queue != rx_queue ||
                entry->last_frag + 1 != frag)
                  continue;

            f_hdr = (struct ieee80211_hdr *) entry->skb_list.next->data;
            f_fc = le16_to_cpu(f_hdr->frame_control);

            if ((fc & IEEE80211_FCTL_FTYPE) != (f_fc & IEEE80211_FCTL_FTYPE) ||
                compare_ether_addr(hdr->addr1, f_hdr->addr1) != 0 ||
                compare_ether_addr(hdr->addr2, f_hdr->addr2) != 0)
                  continue;

            if (entry->first_frag_time + 2 * HZ < jiffies) {
                  __skb_queue_purge(&entry->skb_list);
                  continue;
            }
            return entry;
      }

      return NULL;
}

static ieee80211_txrx_result
ieee80211_rx_h_defragment(struct ieee80211_txrx_data *rx)
{
      struct ieee80211_hdr *hdr;
      u16 sc;
      unsigned int frag, seq;
      struct ieee80211_fragment_entry *entry;
      struct sk_buff *skb;
      DECLARE_MAC_BUF(mac);

      hdr = (struct ieee80211_hdr *) rx->skb->data;
      sc = le16_to_cpu(hdr->seq_ctrl);
      frag = sc & IEEE80211_SCTL_FRAG;

      if (likely((!(rx->fc & IEEE80211_FCTL_MOREFRAGS) && frag == 0) ||
               (rx->skb)->len < 24 ||
               is_multicast_ether_addr(hdr->addr1))) {
            /* not fragmented */
            goto out;
      }
      I802_DEBUG_INC(rx->local->rx_handlers_fragments);

      seq = (sc & IEEE80211_SCTL_SEQ) >> 4;

      if (frag == 0) {
            /* This is the first fragment of a new frame. */
            entry = ieee80211_reassemble_add(rx->sdata, frag, seq,
                                     rx->u.rx.queue, &(rx->skb));
            if (rx->key && rx->key->conf.alg == ALG_CCMP &&
                (rx->fc & IEEE80211_FCTL_PROTECTED)) {
                  /* Store CCMP PN so that we can verify that the next
                   * fragment has a sequential PN value. */
                  entry->ccmp = 1;
                  memcpy(entry->last_pn,
                         rx->key->u.ccmp.rx_pn[rx->u.rx.queue],
                         CCMP_PN_LEN);
            }
            return TXRX_QUEUED;
      }

      /* This is a fragment for a frame that should already be pending in
       * fragment cache. Add this fragment to the end of the pending entry.
       */
      entry = ieee80211_reassemble_find(rx->sdata, rx->fc, frag, seq,
                                rx->u.rx.queue, hdr);
      if (!entry) {
            I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
            return TXRX_DROP;
      }

      /* Verify that MPDUs within one MSDU have sequential PN values.
       * (IEEE 802.11i, 8.3.3.4.5) */
      if (entry->ccmp) {
            int i;
            u8 pn[CCMP_PN_LEN], *rpn;
            if (!rx->key || rx->key->conf.alg != ALG_CCMP)
                  return TXRX_DROP;
            memcpy(pn, entry->last_pn, CCMP_PN_LEN);
            for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
                  pn[i]++;
                  if (pn[i])
                        break;
            }
            rpn = rx->key->u.ccmp.rx_pn[rx->u.rx.queue];
            if (memcmp(pn, rpn, CCMP_PN_LEN) != 0) {
                  if (net_ratelimit())
                        printk(KERN_DEBUG "%s: defrag: CCMP PN not "
                               "sequential A2=%s"
                               " PN=%02x%02x%02x%02x%02x%02x "
                               "(expected %02x%02x%02x%02x%02x%02x)\n",
                               rx->dev->name, print_mac(mac, hdr->addr2),
                               rpn[0], rpn[1], rpn[2], rpn[3], rpn[4],
                               rpn[5], pn[0], pn[1], pn[2], pn[3],
                               pn[4], pn[5]);
                  return TXRX_DROP;
            }
            memcpy(entry->last_pn, pn, CCMP_PN_LEN);
      }

      skb_pull(rx->skb, ieee80211_get_hdrlen(rx->fc));
      __skb_queue_tail(&entry->skb_list, rx->skb);
      entry->last_frag = frag;
      entry->extra_len += rx->skb->len;
      if (rx->fc & IEEE80211_FCTL_MOREFRAGS) {
            rx->skb = NULL;
            return TXRX_QUEUED;
      }

      rx->skb = __skb_dequeue(&entry->skb_list);
      if (skb_tailroom(rx->skb) < entry->extra_len) {
            I802_DEBUG_INC(rx->local->rx_expand_skb_head2);
            if (unlikely(pskb_expand_head(rx->skb, 0, entry->extra_len,
                                    GFP_ATOMIC))) {
                  I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
                  __skb_queue_purge(&entry->skb_list);
                  return TXRX_DROP;
            }
      }
      while ((skb = __skb_dequeue(&entry->skb_list))) {
            memcpy(skb_put(rx->skb, skb->len), skb->data, skb->len);
            dev_kfree_skb(skb);
      }

      /* Complete frame has been reassembled - process it now */
      rx->flags |= IEEE80211_TXRXD_FRAGMENTED;

 out:
      if (rx->sta)
            rx->sta->rx_packets++;
      if (is_multicast_ether_addr(hdr->addr1))
            rx->local->dot11MulticastReceivedFrameCount++;
      else
            ieee80211_led_rx(rx->local);
      return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_ps_poll(struct ieee80211_txrx_data *rx)
{
      struct sk_buff *skb;
      int no_pending_pkts;
      DECLARE_MAC_BUF(mac);

      if (likely(!rx->sta ||
               (rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_CTL ||
               (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_PSPOLL ||
               !(rx->flags & IEEE80211_TXRXD_RXRA_MATCH)))
            return TXRX_CONTINUE;

      skb = skb_dequeue(&rx->sta->tx_filtered);
      if (!skb) {
            skb = skb_dequeue(&rx->sta->ps_tx_buf);
            if (skb)
                  rx->local->total_ps_buffered--;
      }
      no_pending_pkts = skb_queue_empty(&rx->sta->tx_filtered) &&
            skb_queue_empty(&rx->sta->ps_tx_buf);

      if (skb) {
            struct ieee80211_hdr *hdr =
                  (struct ieee80211_hdr *) skb->data;

            /* tell TX path to send one frame even though the STA may
             * still remain is PS mode after this frame exchange */
            rx->sta->pspoll = 1;

#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
            printk(KERN_DEBUG "STA %s aid %d: PS Poll (entries after %d)\n",
                   print_mac(mac, rx->sta->addr), rx->sta->aid,
                   skb_queue_len(&rx->sta->ps_tx_buf));
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

            /* Use MoreData flag to indicate whether there are more
             * buffered frames for this STA */
            if (no_pending_pkts) {
                  hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_MOREDATA);
                  rx->sta->flags &= ~WLAN_STA_TIM;
            } else
                  hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_MOREDATA);

            dev_queue_xmit(skb);

            if (no_pending_pkts) {
                  if (rx->local->ops->set_tim)
                        rx->local->ops->set_tim(local_to_hw(rx->local),
                                           rx->sta->aid, 0);
                  if (rx->sdata->bss)
                        bss_tim_clear(rx->local, rx->sdata->bss, rx->sta->aid);
            }
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
      } else if (!rx->u.rx.sent_ps_buffered) {
            printk(KERN_DEBUG "%s: STA %s sent PS Poll even "
                   "though there is no buffered frames for it\n",
                   rx->dev->name, print_mac(mac, rx->sta->addr));
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

      }

      /* Free PS Poll skb here instead of returning TXRX_DROP that would
       * count as an dropped frame. */
      dev_kfree_skb(rx->skb);

      return TXRX_QUEUED;
}

static ieee80211_txrx_result
ieee80211_rx_h_remove_qos_control(struct ieee80211_txrx_data *rx)
{
      u16 fc = rx->fc;
      u8 *data = rx->skb->data;
      struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) data;

      if (!WLAN_FC_IS_QOS_DATA(fc))
            return TXRX_CONTINUE;

      /* remove the qos control field, update frame type and meta-data */
      memmove(data + 2, data, ieee80211_get_hdrlen(fc) - 2);
      hdr = (struct ieee80211_hdr *) skb_pull(rx->skb, 2);
      /* change frame type to non QOS */
      rx->fc = fc &= ~IEEE80211_STYPE_QOS_DATA;
      hdr->frame_control = cpu_to_le16(fc);

      return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_802_1x_pae(struct ieee80211_txrx_data *rx)
{
      if (rx->sdata->eapol && ieee80211_is_eapol(rx->skb) &&
          rx->sdata->type != IEEE80211_IF_TYPE_STA &&
          (rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
            return TXRX_CONTINUE;

      if (unlikely(rx->sdata->ieee802_1x &&
                 (rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
                 (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_NULLFUNC &&
                 (!rx->sta || !(rx->sta->flags & WLAN_STA_AUTHORIZED)) &&
                 !ieee80211_is_eapol(rx->skb))) {
#ifdef CONFIG_MAC80211_DEBUG
            struct ieee80211_hdr *hdr =
                  (struct ieee80211_hdr *) rx->skb->data;
            DECLARE_MAC_BUF(mac);
            printk(KERN_DEBUG "%s: dropped frame from %s"
                   " (unauthorized port)\n", rx->dev->name,
                   print_mac(mac, hdr->addr2));
#endif /* CONFIG_MAC80211_DEBUG */
            return TXRX_DROP;
      }

      return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_drop_unencrypted(struct ieee80211_txrx_data *rx)
{
      /*
       * Pass through unencrypted frames if the hardware has
       * decrypted them already.
       */
      if (rx->u.rx.status->flag & RX_FLAG_DECRYPTED)
            return TXRX_CONTINUE;

      /* Drop unencrypted frames if key is set. */
      if (unlikely(!(rx->fc & IEEE80211_FCTL_PROTECTED) &&
                 (rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
                 (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_NULLFUNC &&
                 (rx->key || rx->sdata->drop_unencrypted) &&
                 (rx->sdata->eapol == 0 || !ieee80211_is_eapol(rx->skb)))) {
            if (net_ratelimit())
                  printk(KERN_DEBUG "%s: RX non-WEP frame, but expected "
                         "encryption\n", rx->dev->name);
            return TXRX_DROP;
      }
      return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_data(struct ieee80211_txrx_data *rx)
{
      struct net_device *dev = rx->dev;
      struct ieee80211_local *local = rx->local;
      struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
      u16 fc, hdrlen, ethertype;
      u8 *payload;
      u8 dst[ETH_ALEN];
      u8 src[ETH_ALEN];
      struct sk_buff *skb = rx->skb, *skb2;
      struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
      DECLARE_MAC_BUF(mac);
      DECLARE_MAC_BUF(mac2);
      DECLARE_MAC_BUF(mac3);
      DECLARE_MAC_BUF(mac4);

      fc = rx->fc;
      if (unlikely((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA))
            return TXRX_CONTINUE;

      if (unlikely(!WLAN_FC_DATA_PRESENT(fc)))
            return TXRX_DROP;

      hdrlen = ieee80211_get_hdrlen(fc);

      /* convert IEEE 802.11 header + possible LLC headers into Ethernet
       * header
       * IEEE 802.11 address fields:
       * ToDS FromDS Addr1 Addr2 Addr3 Addr4
       *   0     0   DA    SA    BSSID n/a
       *   0     1   DA    BSSID SA    n/a
       *   1     0   BSSID SA    DA    n/a
       *   1     1   RA    TA    DA    SA
       */

      switch (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
      case IEEE80211_FCTL_TODS:
            /* BSSID SA DA */
            memcpy(dst, hdr->addr3, ETH_ALEN);
            memcpy(src, hdr->addr2, ETH_ALEN);

            if (unlikely(sdata->type != IEEE80211_IF_TYPE_AP &&
                       sdata->type != IEEE80211_IF_TYPE_VLAN)) {
                  if (net_ratelimit())
                        printk(KERN_DEBUG "%s: dropped ToDS frame "
                               "(BSSID=%s SA=%s DA=%s)\n",
                               dev->name,
                               print_mac(mac, hdr->addr1),
                               print_mac(mac2, hdr->addr2),
                               print_mac(mac3, hdr->addr3));
                  return TXRX_DROP;
            }
            break;
      case (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS):
            /* RA TA DA SA */
            memcpy(dst, hdr->addr3, ETH_ALEN);
            memcpy(src, hdr->addr4, ETH_ALEN);

            if (unlikely(sdata->type != IEEE80211_IF_TYPE_WDS)) {
                  if (net_ratelimit())
                        printk(KERN_DEBUG "%s: dropped FromDS&ToDS "
                               "frame (RA=%s TA=%s DA=%s SA=%s)\n",
                               rx->dev->name,
                               print_mac(mac, hdr->addr1),
                               print_mac(mac2, hdr->addr2),
                               print_mac(mac3, hdr->addr3),
                               print_mac(mac4, hdr->addr4));
                  return TXRX_DROP;
            }
            break;
      case IEEE80211_FCTL_FROMDS:
            /* DA BSSID SA */
            memcpy(dst, hdr->addr1, ETH_ALEN);
            memcpy(src, hdr->addr3, ETH_ALEN);

            if (sdata->type != IEEE80211_IF_TYPE_STA ||
                (is_multicast_ether_addr(dst) &&
                 !compare_ether_addr(src, dev->dev_addr)))
                  return TXRX_DROP;
            break;
      case 0:
            /* DA SA BSSID */
            memcpy(dst, hdr->addr1, ETH_ALEN);
            memcpy(src, hdr->addr2, ETH_ALEN);

            if (sdata->type != IEEE80211_IF_TYPE_IBSS) {
                  if (net_ratelimit()) {
                        printk(KERN_DEBUG "%s: dropped IBSS frame "
                               "(DA=%s SA=%s BSSID=%s)\n",
                               dev->name,
                               print_mac(mac, hdr->addr1),
                               print_mac(mac2, hdr->addr2),
                               print_mac(mac3, hdr->addr3));
                  }
                  return TXRX_DROP;
            }
            break;
      }

      payload = skb->data + hdrlen;

      if (unlikely(skb->len - hdrlen < 8)) {
            if (net_ratelimit()) {
                  printk(KERN_DEBUG "%s: RX too short data frame "
                         "payload\n", dev->name);
            }
            return TXRX_DROP;
      }

      ethertype = (payload[6] << 8) | payload[7];

      if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
                ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
               compare_ether_addr(payload, bridge_tunnel_header) == 0)) {
            /* remove RFC1042 or Bridge-Tunnel encapsulation and
             * replace EtherType */
            skb_pull(skb, hdrlen + 6);
            memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
            memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
      } else {
            struct ethhdr *ehdr;
            __be16 len;
            skb_pull(skb, hdrlen);
            len = htons(skb->len);
            ehdr = (struct ethhdr *) skb_push(skb, sizeof(struct ethhdr));
            memcpy(ehdr->h_dest, dst, ETH_ALEN);
            memcpy(ehdr->h_source, src, ETH_ALEN);
            ehdr->h_proto = len;
      }
      skb->dev = dev;

      skb2 = NULL;

      dev->stats.rx_packets++;
      dev->stats.rx_bytes += skb->len;

      if (local->bridge_packets && (sdata->type == IEEE80211_IF_TYPE_AP
          || sdata->type == IEEE80211_IF_TYPE_VLAN) &&
          (rx->flags & IEEE80211_TXRXD_RXRA_MATCH)) {
            if (is_multicast_ether_addr(skb->data)) {
                  /* send multicast frames both to higher layers in
                   * local net stack and back to the wireless media */
                  skb2 = skb_copy(skb, GFP_ATOMIC);
                  if (!skb2 && net_ratelimit())
                        printk(KERN_DEBUG "%s: failed to clone "
                               "multicast frame\n", dev->name);
            } else {
                  struct sta_info *dsta;
                  dsta = sta_info_get(local, skb->data);
                  if (dsta && !dsta->dev) {
                        if (net_ratelimit())
                              printk(KERN_DEBUG "Station with null "
                                     "dev structure!\n");
                  } else if (dsta && dsta->dev == dev) {
                        /* Destination station is associated to this
                         * AP, so send the frame directly to it and
                         * do not pass the frame to local net stack.
                         */
                        skb2 = skb;
                        skb = NULL;
                  }
                  if (dsta)
                        sta_info_put(dsta);
            }
      }

      if (skb) {
            /* deliver to local stack */
            skb->protocol = eth_type_trans(skb, dev);
            memset(skb->cb, 0, sizeof(skb->cb));
            netif_rx(skb);
      }

      if (skb2) {
            /* send to wireless media */
            skb2->protocol = __constant_htons(ETH_P_802_3);
            skb_set_network_header(skb2, 0);
            skb_set_mac_header(skb2, 0);
            dev_queue_xmit(skb2);
      }

      return TXRX_QUEUED;
}

static ieee80211_txrx_result
ieee80211_rx_h_mgmt(struct ieee80211_txrx_data *rx)
{
      struct ieee80211_sub_if_data *sdata;

      if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
            return TXRX_DROP;

      sdata = IEEE80211_DEV_TO_SUB_IF(rx->dev);
      if ((sdata->type == IEEE80211_IF_TYPE_STA ||
           sdata->type == IEEE80211_IF_TYPE_IBSS) &&
          !(sdata->flags & IEEE80211_SDATA_USERSPACE_MLME))
            ieee80211_sta_rx_mgmt(rx->dev, rx->skb, rx->u.rx.status);
      else
            return TXRX_DROP;

      return TXRX_QUEUED;
}

static inline ieee80211_txrx_result __ieee80211_invoke_rx_handlers(
                        struct ieee80211_local *local,
                        ieee80211_rx_handler *handlers,
                        struct ieee80211_txrx_data *rx,
                        struct sta_info *sta)
{
      ieee80211_rx_handler *handler;
      ieee80211_txrx_result res = TXRX_DROP;

      for (handler = handlers; *handler != NULL; handler++) {
            res = (*handler)(rx);

            switch (res) {
            case TXRX_CONTINUE:
                  continue;
            case TXRX_DROP:
                  I802_DEBUG_INC(local->rx_handlers_drop);
                  if (sta)
                        sta->rx_dropped++;
                  break;
            case TXRX_QUEUED:
                  I802_DEBUG_INC(local->rx_handlers_queued);
                  break;
            }
            break;
      }

      if (res == TXRX_DROP)
            dev_kfree_skb(rx->skb);
      return res;
}

static inline void ieee80211_invoke_rx_handlers(struct ieee80211_local *local,
                                    ieee80211_rx_handler *handlers,
                                    struct ieee80211_txrx_data *rx,
                                    struct sta_info *sta)
{
      if (__ieee80211_invoke_rx_handlers(local, handlers, rx, sta) ==
          TXRX_CONTINUE)
            dev_kfree_skb(rx->skb);
}

static void ieee80211_rx_michael_mic_report(struct net_device *dev,
                                  struct ieee80211_hdr *hdr,
                                  struct sta_info *sta,
                                  struct ieee80211_txrx_data *rx)
{
      int keyidx, hdrlen;
      DECLARE_MAC_BUF(mac);
      DECLARE_MAC_BUF(mac2);

      hdrlen = ieee80211_get_hdrlen_from_skb(rx->skb);
      if (rx->skb->len >= hdrlen + 4)
            keyidx = rx->skb->data[hdrlen + 3] >> 6;
      else
            keyidx = -1;

      if (net_ratelimit())
            printk(KERN_DEBUG "%s: TKIP hwaccel reported Michael MIC "
                   "failure from %s to %s keyidx=%d\n",
                   dev->name, print_mac(mac, hdr->addr2),
                   print_mac(mac2, hdr->addr1), keyidx);

      if (!sta) {
            /*
             * Some hardware seem to generate incorrect Michael MIC
             * reports; ignore them to avoid triggering countermeasures.
             */
            if (net_ratelimit())
                  printk(KERN_DEBUG "%s: ignored spurious Michael MIC "
                         "error for unknown address %s\n",
                         dev->name, print_mac(mac, hdr->addr2));
            goto ignore;
      }

      if (!(rx->fc & IEEE80211_FCTL_PROTECTED)) {
            if (net_ratelimit())
                  printk(KERN_DEBUG "%s: ignored spurious Michael MIC "
                         "error for a frame with no PROTECTED flag (src "
                         "%s)\n", dev->name, print_mac(mac, hdr->addr2));
            goto ignore;
      }

      if (rx->sdata->type == IEEE80211_IF_TYPE_AP && keyidx) {
            /*
             * APs with pairwise keys should never receive Michael MIC
             * errors for non-zero keyidx because these are reserved for
             * group keys and only the AP is sending real multicast
             * frames in the BSS.
             */
            if (net_ratelimit())
                  printk(KERN_DEBUG "%s: ignored Michael MIC error for "
                         "a frame with non-zero keyidx (%d)"
                         " (src %s)\n", dev->name, keyidx,
                         print_mac(mac, hdr->addr2));
            goto ignore;
      }

      if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA &&
          ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT ||
           (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_AUTH)) {
            if (net_ratelimit())
                  printk(KERN_DEBUG "%s: ignored spurious Michael MIC "
                         "error for a frame that cannot be encrypted "
                         "(fc=0x%04x) (src %s)\n",
                         dev->name, rx->fc, print_mac(mac, hdr->addr2));
            goto ignore;
      }

      mac80211_ev_michael_mic_failure(rx->dev, keyidx, hdr);
 ignore:
      dev_kfree_skb(rx->skb);
      rx->skb = NULL;
}

ieee80211_rx_handler ieee80211_rx_handlers[] =
{
      ieee80211_rx_h_if_stats,
      ieee80211_rx_h_passive_scan,
      ieee80211_rx_h_check,
      ieee80211_rx_h_decrypt,
      ieee80211_rx_h_sta_process,
      ieee80211_rx_h_defragment,
      ieee80211_rx_h_ps_poll,
      ieee80211_rx_h_michael_mic_verify,
      /* this must be after decryption - so header is counted in MPDU mic
       * must be before pae and data, so QOS_DATA format frames
       * are not passed to user space by these functions
       */
      ieee80211_rx_h_remove_qos_control,
      ieee80211_rx_h_802_1x_pae,
      ieee80211_rx_h_drop_unencrypted,
      ieee80211_rx_h_data,
      ieee80211_rx_h_mgmt,
      NULL
};

/* main receive path */

static int prepare_for_handlers(struct ieee80211_sub_if_data *sdata,
                        u8 *bssid, struct ieee80211_txrx_data *rx,
                        struct ieee80211_hdr *hdr)
{
      int multicast = is_multicast_ether_addr(hdr->addr1);

      switch (sdata->type) {
      case IEEE80211_IF_TYPE_STA:
            if (!bssid)
                  return 0;
            if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
                  if (!(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                        return 0;
                  rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
            } else if (!multicast &&
                     compare_ether_addr(sdata->dev->dev_addr,
                                    hdr->addr1) != 0) {
                  if (!(sdata->dev->flags & IFF_PROMISC))
                        return 0;
                  rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
            }
            break;
      case IEEE80211_IF_TYPE_IBSS:
            if (!bssid)
                  return 0;
            if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
                  if (!(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                        return 0;
                  rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
            } else if (!multicast &&
                     compare_ether_addr(sdata->dev->dev_addr,
                                    hdr->addr1) != 0) {
                  if (!(sdata->dev->flags & IFF_PROMISC))
                        return 0;
                  rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
            } else if (!rx->sta)
                  rx->sta = ieee80211_ibss_add_sta(sdata->dev, rx->skb,
                                           bssid, hdr->addr2);
            break;
      case IEEE80211_IF_TYPE_VLAN:
      case IEEE80211_IF_TYPE_AP:
            if (!bssid) {
                  if (compare_ether_addr(sdata->dev->dev_addr,
                                     hdr->addr1))
                        return 0;
            } else if (!ieee80211_bssid_match(bssid,
                              sdata->dev->dev_addr)) {
                  if (!(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                        return 0;
                  rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
            }
            if (sdata->dev == sdata->local->mdev &&
                !(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                  /* do not receive anything via
                   * master device when not scanning */
                  return 0;
            break;
      case IEEE80211_IF_TYPE_WDS:
            if (bssid ||
                (rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
                  return 0;
            if (compare_ether_addr(sdata->u.wds.remote_addr, hdr->addr2))
                  return 0;
            break;
      case IEEE80211_IF_TYPE_MNTR:
            /* take everything */
            break;
      case IEEE80211_IF_TYPE_INVALID:
            /* should never get here */
            WARN_ON(1);
            break;
      }

      return 1;
}

/*
 * This is the receive path handler. It is called by a low level driver when an
 * 802.11 MPDU is received from the hardware.
 */
void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
                struct ieee80211_rx_status *status)
{
      struct ieee80211_local *local = hw_to_local(hw);
      struct ieee80211_sub_if_data *sdata;
      struct sta_info *sta;
      struct ieee80211_hdr *hdr;
      struct ieee80211_txrx_data rx;
      u16 type;
      int prepres;
      struct ieee80211_sub_if_data *prev = NULL;
      struct sk_buff *skb_new;
      u8 *bssid;

      /*
       * key references and virtual interfaces are protected using RCU
       * and this requires that we are in a read-side RCU section during
       * receive processing
       */
      rcu_read_lock();

      /*
       * Frames with failed FCS/PLCP checksum are not returned,
       * all other frames are returned without radiotap header
       * if it was previously present.
       * Also, frames with less than 16 bytes are dropped.
       */
      skb = ieee80211_rx_monitor(local, skb, status);
      if (!skb) {
            rcu_read_unlock();
            return;
      }

      hdr = (struct ieee80211_hdr *) skb->data;
      memset(&rx, 0, sizeof(rx));
      rx.skb = skb;
      rx.local = local;

      rx.u.rx.status = status;
      rx.fc = le16_to_cpu(hdr->frame_control);
      type = rx.fc & IEEE80211_FCTL_FTYPE;

      if (type == IEEE80211_FTYPE_DATA || type == IEEE80211_FTYPE_MGMT)
            local->dot11ReceivedFragmentCount++;

      sta = rx.sta = sta_info_get(local, hdr->addr2);
      if (sta) {
            rx.dev = rx.sta->dev;
            rx.sdata = IEEE80211_DEV_TO_SUB_IF(rx.dev);
      }

      if ((status->flag & RX_FLAG_MMIC_ERROR)) {
            ieee80211_rx_michael_mic_report(local->mdev, hdr, sta, &rx);
            goto end;
      }

      if (unlikely(local->sta_scanning))
            rx.flags |= IEEE80211_TXRXD_RXIN_SCAN;

      if (__ieee80211_invoke_rx_handlers(local, local->rx_pre_handlers, &rx,
                                 sta) != TXRX_CONTINUE)
            goto end;
      skb = rx.skb;

      if (sta && !(sta->flags & (WLAN_STA_WDS | WLAN_STA_ASSOC_AP)) &&
          !atomic_read(&local->iff_promiscs) &&
          !is_multicast_ether_addr(hdr->addr1)) {
            rx.flags |= IEEE80211_TXRXD_RXRA_MATCH;
            ieee80211_invoke_rx_handlers(local, local->rx_handlers, &rx,
                                   rx.sta);
            sta_info_put(sta);
            rcu_read_unlock();
            return;
      }

      bssid = ieee80211_get_bssid(hdr, skb->len);

      list_for_each_entry_rcu(sdata, &local->interfaces, list) {
            if (!netif_running(sdata->dev))
                  continue;

            if (sdata->type == IEEE80211_IF_TYPE_MNTR)
                  continue;

            rx.flags |= IEEE80211_TXRXD_RXRA_MATCH;
            prepres = prepare_for_handlers(sdata, bssid, &rx, hdr);
            /* prepare_for_handlers can change sta */
            sta = rx.sta;

            if (!prepres)
                  continue;

            /*
             * frame is destined for this interface, but if it's not
             * also for the previous one we handle that after the
             * loop to avoid copying the SKB once too much
             */

            if (!prev) {
                  prev = sdata;
                  continue;
            }

            /*
             * frame was destined for the previous interface
             * so invoke RX handlers for it
             */

            skb_new = skb_copy(skb, GFP_ATOMIC);
            if (!skb_new) {
                  if (net_ratelimit())
                        printk(KERN_DEBUG "%s: failed to copy "
                               "multicast frame for %s",
                               wiphy_name(local->hw.wiphy),
                               prev->dev->name);
                  continue;
            }
            rx.skb = skb_new;
            rx.dev = prev->dev;
            rx.sdata = prev;
            ieee80211_invoke_rx_handlers(local, local->rx_handlers,
                                   &rx, sta);
            prev = sdata;
      }
      if (prev) {
            rx.skb = skb;
            rx.dev = prev->dev;
            rx.sdata = prev;
            ieee80211_invoke_rx_handlers(local, local->rx_handlers,
                                   &rx, sta);
      } else
            dev_kfree_skb(skb);

 end:
      rcu_read_unlock();

      if (sta)
            sta_info_put(sta);
}
EXPORT_SYMBOL(__ieee80211_rx);

/* This is a version of the rx handler that can be called from hard irq
 * context. Post the skb on the queue and schedule the tasklet */
void ieee80211_rx_irqsafe(struct ieee80211_hw *hw, struct sk_buff *skb,
                    struct ieee80211_rx_status *status)
{
      struct ieee80211_local *local = hw_to_local(hw);

      BUILD_BUG_ON(sizeof(struct ieee80211_rx_status) > sizeof(skb->cb));

      skb->dev = local->mdev;
      /* copy status into skb->cb for use by tasklet */
      memcpy(skb->cb, status, sizeof(*status));
      skb->pkt_type = IEEE80211_RX_MSG;
      skb_queue_tail(&local->skb_queue, skb);
      tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee80211_rx_irqsafe);

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