text: /*
   * cfg80211 scan result handling
   *
   * Copyright 2008 Johannes Berg <johannes@sipsolutions.net>
   * Copyright 2013-2014  Intel Mobile Communications GmbH
   * Copyright 2016	Intel Deutschland GmbH
   */
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/netdevice.h>
  #include <linux/wireless.h>
  #include <linux/nl80211.h>
  #include <linux/etherdevice.h>
  #include <net/arp.h>
  #include <net/cfg80211.h>
  #include <net/cfg80211-wext.h>
  #include <net/iw_handler.h>
  #include "core.h"
  #include "nl80211.h"
  #include "wext-compat.h"
  #include "rdev-ops.h"
  
  /**
   * DOC: BSS tree/list structure
   *
   * At the top level, the BSS list is kept in both a list in each
   * registered device (@bss_list) as well as an RB-tree for faster
   * lookup. In the RB-tree, entries can be looked up using their
   * channel, MESHID, MESHCONF (for MBSSes) or channel, BSSID, SSID
   * for other BSSes.
   *
   * Due to the possibility of hidden SSIDs, there's a second level
   * structure, the "hidden_list" and "hidden_beacon_bss" pointer.
   * The hidden_list connects all BSSes belonging to a single AP
   * that has a hidden SSID, and connects beacon and probe response
   * entries. For a probe response entry for a hidden SSID, the
   * hidden_beacon_bss pointer points to the BSS struct holding the
   * beacon's information.
   *
   * Reference counting is done for all these references except for
   * the hidden_list, so that a beacon BSS struct that is otherwise
   * not referenced has one reference for being on the bss_list and
   * one for each probe response entry that points to it using the
   * hidden_beacon_bss pointer. When a BSS struct that has such a
   * pointer is get/put, the refcount update is also propagated to
   * the referenced struct, this ensure that it cannot get removed
   * while somebody is using the probe response version.
   *
   * Note that the hidden_beacon_bss pointer never changes, due to
   * the reference counting. Therefore, no locking is needed for
   * it.
   *
   * Also note that the hidden_beacon_bss pointer is only relevant
   * if the driver uses something other than the IEs, e.g. private
   * data stored stored in the BSS struct, since the beacon IEs are
   * also linked into the probe response struct.
   */
  
  /*
   * Limit the number of BSS entries stored in mac80211. Each one is
   * a bit over 4k at most, so this limits to roughly 4-5M of memory.
   * If somebody wants to really attack this though, they'd likely
   * use small beacons, and only one type of frame, limiting each of
   * the entries to a much smaller size (in order to generate more
   * entries in total, so overhead is bigger.)
   */
  static int bss_entries_limit = 1000;
  module_param(bss_entries_limit, int, 0644);
  MODULE_PARM_DESC(bss_entries_limit,
                   "limit to number of scan BSS entries (per wiphy, default 1000)");
  
  #define IEEE80211_SCAN_RESULT_EXPIRE	(30 * HZ)
  
  static void bss_free(struct cfg80211_internal_bss *bss)
  {
  	struct cfg80211_bss_ies *ies;
  
  	if (WARN_ON(atomic_read(&bss->hold)))
  		return;
  
  	ies = (void *)rcu_access_pointer(bss->pub.beacon_ies);
  	if (ies && !bss->pub.hidden_beacon_bss)
  		kfree_rcu(ies, rcu_head);
  	ies = (void *)rcu_access_pointer(bss->pub.proberesp_ies);
  	if (ies)
  		kfree_rcu(ies, rcu_head);
  
  	/*
  	 * This happens when the module is removed, it doesn't
  	 * really matter any more save for completeness
  	 */
  	if (!list_empty(&bss->hidden_list))
  		list_del(&bss->hidden_list);
  
  	kfree(bss);
  }
  
  static inline void bss_ref_get(struct cfg80211_registered_device *rdev,
  			       struct cfg80211_internal_bss *bss)
  {
  	lockdep_assert_held(&rdev->bss_lock);
  
  	bss->refcount++;
  	if (bss->pub.hidden_beacon_bss) {
  		bss = container_of(bss->pub.hidden_beacon_bss,
  				   struct cfg80211_internal_bss,
  				   pub);
  		bss->refcount++;
  	}
  }
  
  static inline void bss_ref_put(struct cfg80211_registered_device *rdev,
  			       struct cfg80211_internal_bss *bss)
  {
  	lockdep_assert_held(&rdev->bss_lock);
  
  	if (bss->pub.hidden_beacon_bss) {
  		struct cfg80211_internal_bss *hbss;
  		hbss = container_of(bss->pub.hidden_beacon_bss,
  				    struct cfg80211_internal_bss,
  				    pub);
  		hbss->refcount--;
  		if (hbss->refcount == 0)
  			bss_free(hbss);
  	}
  	bss->refcount--;
  	if (bss->refcount == 0)
  		bss_free(bss);
  }
  
  static bool __cfg80211_unlink_bss(struct cfg80211_registered_device *rdev,
  				  struct cfg80211_internal_bss *bss)
  {
  	lockdep_assert_held(&rdev->bss_lock);
  
  	if (!list_empty(&bss->hidden_list)) {
  		/*
  		 * don't remove the beacon entry if it has
  		 * probe responses associated with it
  		 */
  		if (!bss->pub.hidden_beacon_bss)
  			return false;
  		/*
  		 * if it's a probe response entry break its
  		 * link to the other entries in the group
  		 */
  		list_del_init(&bss->hidden_list);
  	}
  
  	list_del_init(&bss->list);
  	rb_erase(&bss->rbn, &rdev->bss_tree);
  	rdev->bss_entries--;
  	WARN_ONCE((rdev->bss_entries == 0) ^ list_empty(&rdev->bss_list),
  		  "rdev bss entries[%d]/list[empty:%d] corruption\n",
  		  rdev->bss_entries, list_empty(&rdev->bss_list));
  	bss_ref_put(rdev, bss);
  	return true;
  }
  
  static void __cfg80211_bss_expire(struct cfg80211_registered_device *rdev,
  				  unsigned long expire_time)
  {
  	struct cfg80211_internal_bss *bss, *tmp;
  	bool expired = false;
  
  	lockdep_assert_held(&rdev->bss_lock);
  
  	list_for_each_entry_safe(bss, tmp, &rdev->bss_list, list) {
  		if (atomic_read(&bss->hold))
  			continue;
  		if (!time_after(expire_time, bss->ts))
  			continue;
  
  		if (__cfg80211_unlink_bss(rdev, bss))
  			expired = true;
  	}
  
  	if (expired)
  		rdev->bss_generation++;
  }
  
  static bool cfg80211_bss_expire_oldest(struct cfg80211_registered_device *rdev)
  {
  	struct cfg80211_internal_bss *bss, *oldest = NULL;
  	bool ret;
  
  	lockdep_assert_held(&rdev->bss_lock);
  
  	list_for_each_entry(bss, &rdev->bss_list, list) {
  		if (atomic_read(&bss->hold))
  			continue;
  
  		if (!list_empty(&bss->hidden_list) &&
  		    !bss->pub.hidden_beacon_bss)
  			continue;
  
  		if (oldest && time_before(oldest->ts, bss->ts))
  			continue;
  		oldest = bss;
  	}
  
  	if (WARN_ON(!oldest))
  		return false;
  
  	/*
  	 * The callers make sure to increase rdev->bss_generation if anything
  	 * gets removed (and a new entry added), so there's no need to also do
  	 * it here.
  	 */
  
  	ret = __cfg80211_unlink_bss(rdev, oldest);
  	WARN_ON(!ret);
  	return ret;
  }
  
  void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev,
  			   bool send_message)
  {
  	struct cfg80211_scan_request *request;
  	struct wireless_dev *wdev;
  	struct sk_buff *msg;
  #ifdef CONFIG_CFG80211_WEXT
  	union iwreq_data wrqu;
  #endif
  
  	ASSERT_RTNL();
  
  	if (rdev->scan_msg) {
  		nl80211_send_scan_result(rdev, rdev->scan_msg);
  		rdev->scan_msg = NULL;
  		return;
  	}
  
  	request = rdev->scan_req;
  	if (!request)
  		return;
  
  	wdev = request->wdev;
  
  	/*
  	 * This must be before sending the other events!
  	 * Otherwise, wpa_supplicant gets completely confused with
  	 * wext events.
  	 */
  	if (wdev->netdev)
  		cfg80211_sme_scan_done(wdev->netdev);
  
  	if (!request->info.aborted &&
  	    request->flags & NL80211_SCAN_FLAG_FLUSH) {
  		/* flush entries from previous scans */
  		spin_lock_bh(&rdev->bss_lock);
  		__cfg80211_bss_expire(rdev, request->scan_start);
  		spin_unlock_bh(&rdev->bss_lock);
  	}
  
  	msg = nl80211_build_scan_msg(rdev, wdev, request->info.aborted);
  
  #ifdef CONFIG_CFG80211_WEXT
  	if (wdev->netdev && !request->info.aborted) {
  		memset(&wrqu, 0, sizeof(wrqu));
  
  		wireless_send_event(wdev->netdev, SIOCGIWSCAN, &wrqu, NULL);
  	}
  #endif
  
  	if (wdev->netdev)
  		dev_put(wdev->netdev);
  
  	rdev->scan_req = NULL;
  	kfree(request);
  
  	if (!send_message)
  		rdev->scan_msg = msg;
  	else
  		nl80211_send_scan_result(rdev, msg);
  }
  
  void __cfg80211_scan_done(struct work_struct *wk)
  {
  	struct cfg80211_registered_device *rdev;
  
  	rdev = container_of(wk, struct cfg80211_registered_device,
  			    scan_done_wk);
  
  	rtnl_lock();
  	___cfg80211_scan_done(rdev, true);
  	rtnl_unlock();
  }
  
  void cfg80211_scan_done(struct cfg80211_scan_request *request,
  			struct cfg80211_scan_info *info)
  {
  	trace_cfg80211_scan_done(request, info);
  	WARN_ON(request != wiphy_to_rdev(request->wiphy)->scan_req);
  
  	request->info = *info;
  	request->notified = true;
  	queue_work(cfg80211_wq, &wiphy_to_rdev(request->wiphy)->scan_done_wk);
  }
  EXPORT_SYMBOL(cfg80211_scan_done);
  
  void __cfg80211_sched_scan_results(struct work_struct *wk)
  {
  	struct cfg80211_registered_device *rdev;
  	struct cfg80211_sched_scan_request *request;
  
  	rdev = container_of(wk, struct cfg80211_registered_device,
  			    sched_scan_results_wk);
  
  	rtnl_lock();
  
  	request = rtnl_dereference(rdev->sched_scan_req);
  
  	/* we don't have sched_scan_req anymore if the scan is stopping */
  	if (request) {
  		if (request->flags & NL80211_SCAN_FLAG_FLUSH) {
  			/* flush entries from previous scans */
  			spin_lock_bh(&rdev->bss_lock);
  			__cfg80211_bss_expire(rdev, request->scan_start);
  			spin_unlock_bh(&rdev->bss_lock);
  			request->scan_start = jiffies;
  		}
  		nl80211_send_sched_scan_results(rdev, request->dev);
  	}
  
  	rtnl_unlock();
  }
  
  void cfg80211_sched_scan_results(struct wiphy *wiphy)
  {
  	trace_cfg80211_sched_scan_results(wiphy);
  	/* ignore if we're not scanning */
  
  	if (rcu_access_pointer(wiphy_to_rdev(wiphy)->sched_scan_req))
  		queue_work(cfg80211_wq,
  			   &wiphy_to_rdev(wiphy)->sched_scan_results_wk);
  }
  EXPORT_SYMBOL(cfg80211_sched_scan_results);
  
  void cfg80211_sched_scan_stopped_rtnl(struct wiphy *wiphy)
  {
  	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
  
  	ASSERT_RTNL();
  
  	trace_cfg80211_sched_scan_stopped(wiphy);
  
  	__cfg80211_stop_sched_scan(rdev, true);
  }
  EXPORT_SYMBOL(cfg80211_sched_scan_stopped_rtnl);
  
  void cfg80211_sched_scan_stopped(struct wiphy *wiphy)
  {
  	rtnl_lock();
  	cfg80211_sched_scan_stopped_rtnl(wiphy);
  	rtnl_unlock();
  }
  EXPORT_SYMBOL(cfg80211_sched_scan_stopped);
  
  int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
  			       bool driver_initiated)
  {
  	struct cfg80211_sched_scan_request *sched_scan_req;
  	struct net_device *dev;
  
  	ASSERT_RTNL();
  
  	if (!rdev->sched_scan_req)
  		return -ENOENT;
  
  	sched_scan_req = rtnl_dereference(rdev->sched_scan_req);
  	dev = sched_scan_req->dev;
  
  	if (!driver_initiated) {
  		int err = rdev_sched_scan_stop(rdev, dev);
  		if (err)
  			return err;
  	}
  
  	nl80211_send_sched_scan(rdev, dev, NL80211_CMD_SCHED_SCAN_STOPPED);
  
  	RCU_INIT_POINTER(rdev->sched_scan_req, NULL);
  	kfree_rcu(sched_scan_req, rcu_head);
  
  	return 0;
  }
  
  void cfg80211_bss_age(struct cfg80211_registered_device *rdev,
                        unsigned long age_secs)
  {
  	struct cfg80211_internal_bss *bss;
  	unsigned long age_jiffies = msecs_to_jiffies(age_secs * MSEC_PER_SEC);
  
  	spin_lock_bh(&rdev->bss_lock);
  	list_for_each_entry(bss, &rdev->bss_list, list)
  		bss->ts -= age_jiffies;
  	spin_unlock_bh(&rdev->bss_lock);
  }
  
  void cfg80211_bss_expire(struct cfg80211_registered_device *rdev)
  {
  	__cfg80211_bss_expire(rdev, jiffies - IEEE80211_SCAN_RESULT_EXPIRE);
  }
  
  const u8 *cfg80211_find_ie_match(u8 eid, const u8 *ies, int len,
  				 const u8 *match, int match_len,
  				 int match_offset)
  {
  	/* match_offset can't be smaller than 2, unless match_len is
  	 * zero, in which case match_offset must be zero as well.
  	 */
  	if (WARN_ON((match_len && match_offset < 2) ||
  		    (!match_len && match_offset)))
  		return NULL;
  
  	while (len >= 2 && len >= ies[1] + 2) {
  		if ((ies[0] == eid) &&
  		    (ies[1] + 2 >= match_offset + match_len) &&
  		    !memcmp(ies + match_offset, match, match_len))
  			return ies;
  
  		len -= ies[1] + 2;
  		ies += ies[1] + 2;
  	}
  
  	return NULL;
  }
  EXPORT_SYMBOL(cfg80211_find_ie_match);
  
  const u8 *cfg80211_find_vendor_ie(unsigned int oui, int oui_type,
  				  const u8 *ies, int len)
  {
  	const u8 *ie;
  	u8 match[] = { oui >> 16, oui >> 8, oui, oui_type };
  	int match_len = (oui_type < 0) ? 3 : sizeof(match);
  
  	if (WARN_ON(oui_type > 0xff))
  		return NULL;
  
  	ie = cfg80211_find_ie_match(WLAN_EID_VENDOR_SPECIFIC, ies, len,
  				    match, match_len, 2);
  
  	if (ie && (ie[1] < 4))
  		return NULL;
  
  	return ie;
  }
  EXPORT_SYMBOL(cfg80211_find_vendor_ie);
  
  static bool is_bss(struct cfg80211_bss *a, const u8 *bssid,
  		   const u8 *ssid, size_t ssid_len)
  {
  	const struct cfg80211_bss_ies *ies;
  	const u8 *ssidie;
  
  	if (bssid && !ether_addr_equal(a->bssid, bssid))
  		return false;
  
  	if (!ssid)
  		return true;
  
  	ies = rcu_access_pointer(a->ies);
  	if (!ies)
  		return false;
  	ssidie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
  	if (!ssidie)
  		return false;
  	if (ssidie[1] != ssid_len)
  		return false;
  	return memcmp(ssidie + 2, ssid, ssid_len) == 0;
  }
  
  /**
   * enum bss_compare_mode - BSS compare mode
   * @BSS_CMP_REGULAR: regular compare mode (for insertion and normal find)
   * @BSS_CMP_HIDE_ZLEN: find hidden SSID with zero-length mode
   * @BSS_CMP_HIDE_NUL: find hidden SSID with NUL-ed out mode
   */
  enum bss_compare_mode {
  	BSS_CMP_REGULAR,
  	BSS_CMP_HIDE_ZLEN,
  	BSS_CMP_HIDE_NUL,
  };
  
  static int cmp_bss(struct cfg80211_bss *a,
  		   struct cfg80211_bss *b,
  		   enum bss_compare_mode mode)
  {
  	const struct cfg80211_bss_ies *a_ies, *b_ies;
  	const u8 *ie1 = NULL;
  	const u8 *ie2 = NULL;
  	int i, r;
  
  	if (a->channel != b->channel)
  		return b->channel->center_freq - a->channel->center_freq;
  
  	a_ies = rcu_access_pointer(a->ies);
  	if (!a_ies)
  		return -1;
  	b_ies = rcu_access_pointer(b->ies);
  	if (!b_ies)
  		return 1;
  
  	if (WLAN_CAPABILITY_IS_STA_BSS(a->capability))
  		ie1 = cfg80211_find_ie(WLAN_EID_MESH_ID,
  				       a_ies->data, a_ies->len);
  	if (WLAN_CAPABILITY_IS_STA_BSS(b->capability))
  		ie2 = cfg80211_find_ie(WLAN_EID_MESH_ID,
  				       b_ies->data, b_ies->len);
  	if (ie1 && ie2) {
  		int mesh_id_cmp;
  
  		if (ie1[1] == ie2[1])
  			mesh_id_cmp = memcmp(ie1 + 2, ie2 + 2, ie1[1]);
  		else
  			mesh_id_cmp = ie2[1] - ie1[1];
  
  		ie1 = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
  				       a_ies->data, a_ies->len);
  		ie2 = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
  				       b_ies->data, b_ies->len);
  		if (ie1 && ie2) {
  			if (mesh_id_cmp)
  				return mesh_id_cmp;
  			if (ie1[1] != ie2[1])
  				return ie2[1] - ie1[1];
  			return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
  		}
  	}
  
  	r = memcmp(a->bssid, b->bssid, sizeof(a->bssid));
  	if (r)
  		return r;
  
  	ie1 = cfg80211_find_ie(WLAN_EID_SSID, a_ies->data, a_ies->len);
  	ie2 = cfg80211_find_ie(WLAN_EID_SSID, b_ies->data, b_ies->len);
  
  	if (!ie1 && !ie2)
  		return 0;
  
  	/*
  	 * Note that with "hide_ssid", the function returns a match if
  	 * the already-present BSS ("b") is a hidden SSID beacon for
  	 * the new BSS ("a").
  	 */
  
  	/* sort missing IE before (left of) present IE */
  	if (!ie1)
  		return -1;
  	if (!ie2)
  		return 1;
  
  	switch (mode) {
  	case BSS_CMP_HIDE_ZLEN:
  		/*
  		 * In ZLEN mode we assume the BSS entry we're
  		 * looking for has a zero-length SSID. So if
  		 * the one we're looking at right now has that,
  		 * return 0. Otherwise, return the difference
  		 * in length, but since we're looking for the
  		 * 0-length it's really equivalent to returning
  		 * the length of the one we're looking at.
  		 *
  		 * No content comparison is needed as we assume
  		 * the content length is zero.
  		 */
  		return ie2[1];
  	case BSS_CMP_REGULAR:
  	default:
  		/* sort by length first, then by contents */
  		if (ie1[1] != ie2[1])
  			return ie2[1] - ie1[1];
  		return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
  	case BSS_CMP_HIDE_NUL:
  		if (ie1[1] != ie2[1])
  			return ie2[1] - ie1[1];
  		/* this is equivalent to memcmp(zeroes, ie2 + 2, len) */
  		for (i = 0; i < ie2[1]; i++)
  			if (ie2[i + 2])
  				return -1;
  		return 0;
  	}
  }
  
  static bool cfg80211_bss_type_match(u16 capability,
  				    enum nl80211_band band,
  				    enum ieee80211_bss_type bss_type)
  {
  	bool ret = true;
  	u16 mask, val;
  
  	if (bss_type == IEEE80211_BSS_TYPE_ANY)
  		return ret;
  
  	if (band == NL80211_BAND_60GHZ) {
  		mask = WLAN_CAPABILITY_DMG_TYPE_MASK;
  		switch (bss_type) {
  		case IEEE80211_BSS_TYPE_ESS:
  			val = WLAN_CAPABILITY_DMG_TYPE_AP;
  			break;
  		case IEEE80211_BSS_TYPE_PBSS:
  			val = WLAN_CAPABILITY_DMG_TYPE_PBSS;
  			break;
  		case IEEE80211_BSS_TYPE_IBSS:
  			val = WLAN_CAPABILITY_DMG_TYPE_IBSS;
  			break;
  		default:
  			return false;
  		}
  	} else {
  		mask = WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS;
  		switch (bss_type) {
  		case IEEE80211_BSS_TYPE_ESS:
  			val = WLAN_CAPABILITY_ESS;
  			break;
  		case IEEE80211_BSS_TYPE_IBSS:
  			val = WLAN_CAPABILITY_IBSS;
  			break;
  		case IEEE80211_BSS_TYPE_MBSS:
  			val = 0;
  			break;
  		default:
  			return false;
  		}
  	}
  
  	ret = ((capability & mask) == val);
  	return ret;
  }
  
  /* Returned bss is reference counted and must be cleaned up appropriately. */
  struct cfg80211_bss *cfg80211_get_bss(struct wiphy *wiphy,
  				      struct ieee80211_channel *channel,
  				      const u8 *bssid,
  				      const u8 *ssid, size_t ssid_len,
  				      enum ieee80211_bss_type bss_type,
  				      enum ieee80211_privacy privacy)
  {
  	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
  	struct cfg80211_internal_bss *bss, *res = NULL;
  	unsigned long now = jiffies;
  	int bss_privacy;
  
  	trace_cfg80211_get_bss(wiphy, channel, bssid, ssid, ssid_len, bss_type,
  			       privacy);
  
  	spin_lock_bh(&rdev->bss_lock);
  
  	list_for_each_entry(bss, &rdev->bss_list, list) {
  		if (!cfg80211_bss_type_match(bss->pub.capability,
  					     bss->pub.channel->band, bss_type))
  			continue;
  
  		bss_privacy = (bss->pub.capability & WLAN_CAPABILITY_PRIVACY);
  		if ((privacy == IEEE80211_PRIVACY_ON && !bss_privacy) ||
  		    (privacy == IEEE80211_PRIVACY_OFF && bss_privacy))
  			continue;
  		if (channel && bss->pub.channel != channel)
  			continue;
  		if (!is_valid_ether_addr(bss->pub.bssid))
  			continue;
  		/* Don't get expired BSS structs */
  		if (time_after(now, bss->ts + IEEE80211_SCAN_RESULT_EXPIRE) &&
  		    !atomic_read(&bss->hold))
  			continue;
  		if (is_bss(&bss->pub, bssid, ssid, ssid_len)) {
  			res = bss;
  			bss_ref_get(rdev, res);
  			break;
  		}
  	}
  
  	spin_unlock_bh(&rdev->bss_lock);
  	if (!res)
  		return NULL;
  	trace_cfg80211_return_bss(&res->pub);
  	return &res->pub;
  }
  EXPORT_SYMBOL(cfg80211_get_bss);
  
  static void rb_insert_bss(struct cfg80211_registered_device *rdev,
  			  struct cfg80211_internal_bss *bss)
  {
  	struct rb_node **p = &rdev->bss_tree.rb_node;
  	struct rb_node *parent = NULL;
  	struct cfg80211_internal_bss *tbss;
  	int cmp;
  
  	while (*p) {
  		parent = *p;
  		tbss = rb_entry(parent, struct cfg80211_internal_bss, rbn);
  
  		cmp = cmp_bss(&bss->pub, &tbss->pub, BSS_CMP_REGULAR);
  
  		if (WARN_ON(!cmp)) {
  			/* will sort of leak this BSS */
  			return;
  		}
  
  		if (cmp < 0)
  			p = &(*p)->rb_left;
  		else
  			p = &(*p)->rb_right;
  	}
  
  	rb_link_node(&bss->rbn, parent, p);
  	rb_insert_color(&bss->rbn, &rdev->bss_tree);
  }
  
  static struct cfg80211_internal_bss *
  rb_find_bss(struct cfg80211_registered_device *rdev,
  	    struct cfg80211_internal_bss *res,
  	    enum bss_compare_mode mode)
  {
  	struct rb_node *n = rdev->bss_tree.rb_node;
  	struct cfg80211_internal_bss *bss;
  	int r;
  
  	while (n) {
  		bss = rb_entry(n, struct cfg80211_internal_bss, rbn);
  		r = cmp_bss(&res->pub, &bss->pub, mode);
  
  		if (r == 0)
  			return bss;
  		else if (r < 0)
  			n = n->rb_left;
  		else
  			n = n->rb_right;
  	}
  
  	return NULL;
  }
  
  static bool cfg80211_combine_bsses(struct cfg80211_registered_device *rdev,
  				   struct cfg80211_internal_bss *new)
  {
  	const struct cfg80211_bss_ies *ies;
  	struct cfg80211_internal_bss *bss;
  	const u8 *ie;
  	int i, ssidlen;
  	u8 fold = 0;
  	u32 n_entries = 0;
  
  	ies = rcu_access_pointer(new->pub.beacon_ies);
  	if (WARN_ON(!ies))
  		return false;
  
  	ie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
  	if (!ie) {
  		/* nothing to do */
  		return true;
  	}
  
  	ssidlen = ie[1];
  	for (i = 0; i < ssidlen; i++)
  		fold |= ie[2 + i];
  
  	if (fold) {
  		/* not a hidden SSID */
  		return true;
  	}
  
  	/* This is the bad part ... */
  
  	list_for_each_entry(bss, &rdev->bss_list, list) {
  		/*
  		 * we're iterating all the entries anyway, so take the
  		 * opportunity to validate the list length accounting
  		 */
  		n_entries++;
  
  		if (!ether_addr_equal(bss->pub.bssid, new->pub.bssid))
  			continue;
  		if (bss->pub.channel != new->pub.channel)
  			continue;
  		if (bss->pub.scan_width != new->pub.scan_width)
  			continue;
  		if (rcu_access_pointer(bss->pub.beacon_ies))
  			continue;
  		ies = rcu_access_pointer(bss->pub.ies);
  		if (!ies)
  			continue;
  		ie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
  		if (!ie)
  			continue;
  		if (ssidlen && ie[1] != ssidlen)
  			continue;
  		if (WARN_ON_ONCE(bss->pub.hidden_beacon_bss))
  			continue;
  		if (WARN_ON_ONCE(!list_empty(&bss->hidden_list)))
  			list_del(&bss->hidden_list);
  		/* combine them */
  		list_add(&bss->hidden_list, &new->hidden_list);
  		bss->pub.hidden_beacon_bss = &new->pub;
  		new->refcount += bss->refcount;
  		rcu_assign_pointer(bss->pub.beacon_ies,
  				   new->pub.beacon_ies);
  	}
  
  	WARN_ONCE(n_entries != rdev->bss_entries,
  		  "rdev bss entries[%d]/list[len:%d] corruption\n",
  		  rdev->bss_entries, n_entries);
  
  	return true;
  }
  
  /* Returned bss is reference counted and must be cleaned up appropriately. */
  static struct cfg80211_internal_bss *
  cfg80211_bss_update(struct cfg80211_registered_device *rdev,
  		    struct cfg80211_internal_bss *tmp,
  		    bool signal_valid)
  {
  	struct cfg80211_internal_bss *found = NULL;
  
  	if (WARN_ON(!tmp->pub.channel))
  		return NULL;
  
  	tmp->ts = jiffies;
  
  	spin_lock_bh(&rdev->bss_lock);
  
  	if (WARN_ON(!rcu_access_pointer(tmp->pub.ies))) {
  		spin_unlock_bh(&rdev->bss_lock);
  		return NULL;
  	}
  
  	found = rb_find_bss(rdev, tmp, BSS_CMP_REGULAR);
  
  	if (found) {
  		/* Update IEs */
  		if (rcu_access_pointer(tmp->pub.proberesp_ies)) {
  			const struct cfg80211_bss_ies *old;
  
  			old = rcu_access_pointer(found->pub.proberesp_ies);
  
  			rcu_assign_pointer(found->pub.proberesp_ies,
  					   tmp->pub.proberesp_ies);
  			/* Override possible earlier Beacon frame IEs */
  			rcu_assign_pointer(found->pub.ies,
  					   tmp->pub.proberesp_ies);
  			if (old)
  				kfree_rcu((struct cfg80211_bss_ies *)old,
  					  rcu_head);
  		} else if (rcu_access_pointer(tmp->pub.beacon_ies)) {
  			const struct cfg80211_bss_ies *old;
  			struct cfg80211_internal_bss *bss;
  
  			if (found->pub.hidden_beacon_bss &&
  			    !list_empty(&found->hidden_list)) {
  				const struct cfg80211_bss_ies *f;
  
  				/*
  				 * The found BSS struct is one of the probe
  				 * response members of a group, but we're
  				 * receiving a beacon (beacon_ies in the tmp
  				 * bss is used). This can only mean that the
  				 * AP changed its beacon from not having an
  				 * SSID to showing it, which is confusing so
  				 * drop this information.
  				 */
  
  				f = rcu_access_pointer(tmp->pub.beacon_ies);
  				kfree_rcu((struct cfg80211_bss_ies *)f,
  					  rcu_head);
  				goto drop;
  			}
  
  			old = rcu_access_pointer(found->pub.beacon_ies);
  
  			rcu_assign_pointer(found->pub.beacon_ies,
  					   tmp->pub.beacon_ies);
  
  			/* Override IEs if they were from a beacon before */
  			if (old == rcu_access_pointer(found->pub.ies))
  				rcu_assign_pointer(found->pub.ies,
  						   tmp->pub.beacon_ies);
  
  			/* Assign beacon IEs to all sub entries */
  			list_for_each_entry(bss, &found->hidden_list,
  					    hidden_list) {
  				const struct cfg80211_bss_ies *ies;
  
  				ies = rcu_access_pointer(bss->pub.beacon_ies);
  				WARN_ON(ies != old);
  
  				rcu_assign_pointer(bss->pub.beacon_ies,
  						   tmp->pub.beacon_ies);
  			}
  
  			if (old)
  				kfree_rcu((struct cfg80211_bss_ies *)old,
  					  rcu_head);
  		}
  
  		found->pub.beacon_interval = tmp->pub.beacon_interval;
  		/*
  		 * don't update the signal if beacon was heard on
  		 * adjacent channel.
  		 */
  		if (signal_valid)
  			found->pub.signal = tmp->pub.signal;
  		found->pub.capability = tmp->pub.capability;
  		found->ts = tmp->ts;
  		found->ts_boottime = tmp->ts_boottime;
  		found->parent_tsf = tmp->parent_tsf;
  		ether_addr_copy(found->parent_bssid, tmp->parent_bssid);
  	} else {
  		struct cfg80211_internal_bss *new;
  		struct cfg80211_internal_bss *hidden;
  		struct cfg80211_bss_ies *ies;
  
  		/*
  		 * create a copy -- the "res" variable that is passed in
  		 * is allocated on the stack since it's not needed in the
  		 * more common case of an update
  		 */
  		new = kzalloc(sizeof(*new) + rdev->wiphy.bss_priv_size,
  			      GFP_ATOMIC);
  		if (!new) {
  			ies = (void *)rcu_dereference(tmp->pub.beacon_ies);
  			if (ies)
  				kfree_rcu(ies, rcu_head);
  			ies = (void *)rcu_dereference(tmp->pub.proberesp_ies);
  			if (ies)
  				kfree_rcu(ies, rcu_head);
  			goto drop;
  		}
  		memcpy(new, tmp, sizeof(*new));
  		new->refcount = 1;
  		INIT_LIST_HEAD(&new->hidden_list);
  
  		if (rcu_access_pointer(tmp->pub.proberesp_ies)) {
  			hidden = rb_find_bss(rdev, tmp, BSS_CMP_HIDE_ZLEN);
  			if (!hidden)
  				hidden = rb_find_bss(rdev, tmp,
  						     BSS_CMP_HIDE_NUL);
  			if (hidden) {
  				new->pub.hidden_beacon_bss = &hidden->pub;
  				list_add(&new->hidden_list,
  					 &hidden->hidden_list);
  				hidden->refcount++;
  				rcu_assign_pointer(new->pub.beacon_ies,
  						   hidden->pub.beacon_ies);
  			}
  		} else {
  			/*
  			 * Ok so we found a beacon, and don't have an entry. If
  			 * it's a beacon with hidden SSID, we might be in for an
  			 * expensive search for any probe responses that should
  			 * be grouped with this beacon for updates ...
  			 */
  			if (!cfg80211_combine_bsses(rdev, new)) {
  				kfree(new);
  				goto drop;
  			}
  		}
  
  		if (rdev->bss_entries >= bss_entries_limit &&
  		    !cfg80211_bss_expire_oldest(rdev)) {
  			kfree(new);
  			goto drop;
  		}
  
  		list_add_tail(&new->list, &rdev->bss_list);
  		rdev->bss_entries++;
  		rb_insert_bss(rdev, new);
  		found = new;
  	}
  
  	rdev->bss_generation++;
  	bss_ref_get(rdev, found);
  	spin_unlock_bh(&rdev->bss_lock);
  
  	return found;
   drop:
  	spin_unlock_bh(&rdev->bss_lock);
  	return NULL;
  }
  
  static struct ieee80211_channel *
  cfg80211_get_bss_channel(struct wiphy *wiphy, const u8 *ie, size_t ielen,
  			 struct ieee80211_channel *channel)
  {
  	const u8 *tmp;
  	u32 freq;
  	int channel_number = -1;
  
  	tmp = cfg80211_find_ie(WLAN_EID_DS_PARAMS, ie, ielen);
  	if (tmp && tmp[1] == 1) {
  		channel_number = tmp[2];
  	} else {
  		tmp = cfg80211_find_ie(WLAN_EID_HT_OPERATION, ie, ielen);
  		if (tmp && tmp[1] >= sizeof(struct ieee80211_ht_operation)) {
  			struct ieee80211_ht_operation *htop = (void *)(tmp + 2);
  
  			channel_number = htop->primary_chan;
  		}
  	}
  
  	if (channel_number < 0)
  		return channel;
  
  	freq = ieee80211_channel_to_frequency(channel_number, channel->band);
  	channel = ieee80211_get_channel(wiphy, freq);
  	if (!channel)
  		return NULL;
  	if (channel->flags & IEEE80211_CHAN_DISABLED)
  		return NULL;
  	return channel;
  }
  
  /* Returned bss is reference counted and must be cleaned up appropriately. */
  struct cfg80211_bss *
  cfg80211_inform_bss_data(struct wiphy *wiphy,
  			 struct cfg80211_inform_bss *data,
  			 enum cfg80211_bss_frame_type ftype,
  			 const u8 *bssid, u64 tsf, u16 capability,
  			 u16 beacon_interval, const u8 *ie, size_t ielen,
  			 gfp_t gfp)
  {
  	struct cfg80211_bss_ies *ies;
  	struct ieee80211_channel *channel;
  	struct cfg80211_internal_bss tmp = {}, *res;
  	int bss_type;
  	bool signal_valid;
  
  	if (WARN_ON(!wiphy))
  		return NULL;
  
  	if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
  		    (data->signal < 0 || data->signal > 100)))
  		return NULL;
  
  	channel = cfg80211_get_bss_channel(wiphy, ie, ielen, data->chan);
  	if (!channel)
  		return NULL;
  
  	memcpy(tmp.pub.bssid, bssid, ETH_ALEN);
  	tmp.pub.channel = channel;
  	tmp.pub.scan_width = data->scan_width;
  	tmp.pub.signal = data->signal;
  	tmp.pub.beacon_interval = beacon_interval;
  	tmp.pub.capability = capability;
  	tmp.ts_boottime = data->boottime_ns;
  
  	/*
  	 * If we do not know here whether the IEs are from a Beacon or Probe
  	 * Response frame, we need to pick one of the options and only use it
  	 * with the driver that does not provide the full Beacon/Probe Response
  	 * frame. Use Beacon frame pointer to avoid indicating that this should
  	 * override the IEs pointer should we have received an earlier
  	 * indication of Probe Response data.
  	 */
  	ies = kzalloc(sizeof(*ies) + ielen, gfp);
  	if (!ies)
  		return NULL;
  	ies->len = ielen;
  	ies->tsf = tsf;
  	ies->from_beacon = false;
  	memcpy(ies->data, ie, ielen);
  
  	switch (ftype) {
  	case CFG80211_BSS_FTYPE_BEACON:
  		ies->from_beacon = true;
  		/* fall through to assign */
  	case CFG80211_BSS_FTYPE_UNKNOWN:
  		rcu_assign_pointer(tmp.pub.beacon_ies, ies);
  		break;
  	case CFG80211_BSS_FTYPE_PRESP:
  		rcu_assign_pointer(tmp.pub.proberesp_ies, ies);
  		break;
  	}
  	rcu_assign_pointer(tmp.pub.ies, ies);
  
  	signal_valid = abs(data->chan->center_freq - channel->center_freq) <=
  		wiphy->max_adj_channel_rssi_comp;
  	res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid);
  	if (!res)
  		return NULL;
  
  	if (channel->band == NL80211_BAND_60GHZ) {
  		bss_type = res->pub.capability & WLAN_CAPABILITY_DMG_TYPE_MASK;
  		if (bss_type == WLAN_CAPABILITY_DMG_TYPE_AP ||
  		    bss_type == WLAN_CAPABILITY_DMG_TYPE_PBSS)
  			regulatory_hint_found_beacon(wiphy, channel, gfp);
  	} else {
  		if (res->pub.capability & WLAN_CAPABILITY_ESS)
  			regulatory_hint_found_beacon(wiphy, channel, gfp);
  	}
  
  	trace_cfg80211_return_bss(&res->pub);
  	/* cfg80211_bss_update gives us a referenced result */
  	return &res->pub;
  }
  EXPORT_SYMBOL(cfg80211_inform_bss_data);
  
  /* cfg80211_inform_bss_width_frame helper */
  struct cfg80211_bss *
  cfg80211_inform_bss_frame_data(struct wiphy *wiphy,
  			       struct cfg80211_inform_bss *data,
  			       struct ieee80211_mgmt *mgmt, size_t len,
  			       gfp_t gfp)
  
  {
  	struct cfg80211_internal_bss tmp = {}, *res;
  	struct cfg80211_bss_ies *ies;
  	struct ieee80211_channel *channel;
  	bool signal_valid;
  	size_t ielen = len - offsetof(struct ieee80211_mgmt,
  				      u.probe_resp.variable);
  	int bss_type;
  
  	BUILD_BUG_ON(offsetof(struct ieee80211_mgmt, u.probe_resp.variable) !=
  			offsetof(struct ieee80211_mgmt, u.beacon.variable));
  
  	trace_cfg80211_inform_bss_frame(wiphy, data, mgmt, len);
  
  	if (WARN_ON(!mgmt))
  		return NULL;
  
  	if (WARN_ON(!wiphy))
  		return NULL;
  
  	if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
  		    (data->signal < 0 || data->signal > 100)))
  		return NULL;
  
  	if (WARN_ON(len < offsetof(struct ieee80211_mgmt, u.probe_resp.variable)))
  		return NULL;
  
  	channel = cfg80211_get_bss_channel(wiphy, mgmt->u.beacon.variable,
  					   ielen, data->chan);
  	if (!channel)
  		return NULL;
  
  	ies = kzalloc(sizeof(*ies) + ielen, gfp);
  	if (!ies)
  		return NULL;
  	ies->len = ielen;
  	ies->tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
  	ies->from_beacon = ieee80211_is_beacon(mgmt->frame_control);
  	memcpy(ies->data, mgmt->u.probe_resp.variable, ielen);
  
  	if (ieee80211_is_probe_resp(mgmt->frame_control))
  		rcu_assign_pointer(tmp.pub.proberesp_ies, ies);
  	else
  		rcu_assign_pointer(tmp.pub.beacon_ies, ies);
  	rcu_assign_pointer(tmp.pub.ies, ies);
  	
  	memcpy(tmp.pub.bssid, mgmt->bssid, ETH_ALEN);
  	tmp.pub.channel = channel;
  	tmp.pub.scan_width = data->scan_width;
  	tmp.pub.signal = data->signal;
  	tmp.pub.beacon_interval = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
  	tmp.pub.capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);
  	tmp.ts_boottime = data->boottime_ns;
  	tmp.parent_tsf = data->parent_tsf;
  	ether_addr_copy(tmp.parent_bssid, data->parent_bssid);
  
  	signal_valid = abs(data->chan->center_freq - channel->center_freq) <=
  		wiphy->max_adj_channel_rssi_comp;
  	res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid);
  	if (!res)
  		return NULL;
  
  	if (channel->band == NL80211_BAND_60GHZ) {
  		bss_type = res->pub.capability & WLAN_CAPABILITY_DMG_TYPE_MASK;
  		if (bss_type == WLAN_CAPABILITY_DMG_TYPE_AP ||
  		    bss_type == WLAN_CAPABILITY_DMG_TYPE_PBSS)
  			regulatory_hint_found_beacon(wiphy, channel, gfp);
  	} else {
  		if (res->pub.capability & WLAN_CAPABILITY_ESS)
  			regulatory_hint_found_beacon(wiphy, channel, gfp);
  	}
  
  	trace_cfg80211_return_bss(&res->pub);
  	/* cfg80211_bss_update gives us a referenced result */
  	return &res->pub;
  }
  EXPORT_SYMBOL(cfg80211_inform_bss_frame_data);
  
  void cfg80211_ref_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
  {
  	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
  	struct cfg80211_internal_bss *bss;
  
  	if (!pub)
  		return;
  
  	bss = container_of(pub, struct cfg80211_internal_bss, pub);
  
  	spin_lock_bh(&rdev->bss_lock);
  	bss_ref_get(rdev, bss);
  	spin_unlock_bh(&rdev->bss_lock);
  }
  EXPORT_SYMBOL(cfg80211_ref_bss);
  
  void cfg80211_put_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
  {
  	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
  	struct cfg80211_internal_bss *bss;
  
  	if (!pub)
  		return;
  
  	bss = container_of(pub, struct cfg80211_internal_bss, pub);
  
  	spin_lock_bh(&rdev->bss_lock);
  	bss_ref_put(rdev, bss);
  	spin_unlock_bh(&rdev->bss_lock);
  }
  EXPORT_SYMBOL(cfg80211_put_bss);
  
  void cfg80211_unlink_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
  {
  	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
  	struct cfg80211_internal_bss *bss;
  
  	if (WARN_ON(!pub))
  		return;
  
  	bss = container_of(pub, struct cfg80211_internal_bss, pub);
  
  	spin_lock_bh(&rdev->bss_lock);
  	if (!list_empty(&bss->list)) {
  		if (__cfg80211_unlink_bss(rdev, bss))
  			rdev->bss_generation++;
  	}
  	spin_unlock_bh(&rdev->bss_lock);
  }
  EXPORT_SYMBOL(cfg80211_unlink_bss);
  
  #ifdef CONFIG_CFG80211_WEXT
  static struct cfg80211_registered_device *
  cfg80211_get_dev_from_ifindex(struct net *net, int ifindex)
  {
  	struct cfg80211_registered_device *rdev;
  	struct net_device *dev;
  
  	ASSERT_RTNL();
  
  	dev = dev_get_by_index(net, ifindex);
  	if (!dev)
  		return ERR_PTR(-ENODEV);
  	if (dev->ieee80211_ptr)
  		rdev = wiphy_to_rdev(dev->ieee80211_ptr->wiphy);
  	else
  		rdev = ERR_PTR(-ENODEV);
  	dev_put(dev);
  	return rdev;
  }
  
  int cfg80211_wext_siwscan(struct net_device *dev,
  			  struct iw_request_info *info,
  			  union iwreq_data *wrqu, char *extra)
  {
  	struct cfg80211_registered_device *rdev;
  	struct wiphy *wiphy;
  	struct iw_scan_req *wreq = NULL;
  	struct cfg80211_scan_request *creq = NULL;
  	int i, err, n_channels = 0;
  	enum nl80211_band band;
  
  	if (!netif_running(dev))
  		return -ENETDOWN;
  
  	if (wrqu->data.length == sizeof(struct iw_scan_req))
  		wreq = (struct iw_scan_req *)extra;
  
  	rdev = cfg80211_get_dev_from_ifindex(dev_net(dev), dev->ifindex);
  
  	if (IS_ERR(rdev))
  		return PTR_ERR(rdev);
  
  	if (rdev->scan_req || rdev->scan_msg) {
  		err = -EBUSY;
  		goto out;
  	}
  
  	wiphy = &rdev->wiphy;
  
  	/* Determine number of channels, needed to allocate creq */
  	if (wreq && wreq->num_channels)
  		n_channels = wreq->num_channels;
  	else
  		n_channels = ieee80211_get_num_supported_channels(wiphy);
  
  	creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
  		       n_channels * sizeof(void *),
  		       GFP_ATOMIC);
  	if (!creq) {
  		err = -ENOMEM;
  		goto out;
  	}
  
  	creq->wiphy = wiphy;
  	creq->wdev = dev->ieee80211_ptr;
  	/* SSIDs come after channels */
  	creq->ssids = (void *)&creq->channels[n_channels];
  	creq->n_channels = n_channels;
  	creq->n_ssids = 1;
  	creq->scan_start = jiffies;
  
  	/* translate "Scan on frequencies" request */
  	i = 0;
  	for (band = 0; band < NUM_NL80211_BANDS; band++) {
  		int j;
  
  		if (!wiphy->bands[band])
  			continue;
  
  		for (j = 0; j < wiphy->bands[band]->n_channels; j++) {
  			/* ignore disabled channels */
  			if (wiphy->bands[band]->channels[j].flags &
  						IEEE80211_CHAN_DISABLED)
  				continue;
  
  			/* If we have a wireless request structure and the
  			 * wireless request specifies frequencies, then search
  			 * for the matching hardware channel.
  			 */
  			if (wreq && wreq->num_channels) {
  				int k;
  				int wiphy_freq = wiphy->bands[band]->channels[j].center_freq;
  				for (k = 0; k < wreq->num_channels; k++) {
  					struct iw_freq *freq =
  						&wreq->channel_list[k];
  					int wext_freq =
  						cfg80211_wext_freq(freq);
  
  					if (wext_freq == wiphy_freq)
  						goto wext_freq_found;
  				}
  				goto wext_freq_not_found;
  			}
  
  		wext_freq_found:
  			creq->channels[i] = &wiphy->bands[band]->channels[j];
  			i++;
  		wext_freq_not_found: ;
  		}
  	}
  	/* No channels found? */
  	if (!i) {
  		err = -EINVAL;
  		goto out;
  	}
  
  	/* Set real number of channels specified in creq->channels[] */
  	creq->n_channels = i;
  
  	/* translate "Scan for SSID" request */
  	if (wreq) {
  		if (wrqu->data.flags & IW_SCAN_THIS_ESSID) {
  			if (wreq->essid_len > IEEE80211_MAX_SSID_LEN) {
  				err = -EINVAL;
  				goto out;
  			}
  			memcpy(creq->ssids[0].ssid, wreq->essid, wreq->essid_len);
  			creq->ssids[0].ssid_len = wreq->essid_len;
  		}
  		if (wreq->scan_type == IW_SCAN_TYPE_PASSIVE)
  			creq->n_ssids = 0;
  	}
  
  	for (i = 0; i < NUM_NL80211_BANDS; i++)
  		if (wiphy->bands[i])
  			creq->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;
  
  	eth_broadcast_addr(creq->bssid);
  
  	rdev->scan_req = creq;
  	err = rdev_scan(rdev, creq);
  	if (err) {
  		rdev->scan_req = NULL;
  		/* creq will be freed below */
  	} else {
  		nl80211_send_scan_start(rdev, dev->ieee80211_ptr);
  		/* creq now owned by driver */
  		creq = NULL;
  		dev_hold(dev);
  	}
   out:
  	kfree(creq);
  	return err;
  }
  EXPORT_WEXT_HANDLER(cfg80211_wext_siwscan);
  
  static char *ieee80211_scan_add_ies(struct iw_request_info *info,
  				    const struct cfg80211_bss_ies *ies,
  				    char *current_ev, char *end_buf)
  {
  	const u8 *pos, *end, *next;
  	struct iw_event iwe;
  
  	if (!ies)
  		return current_ev;
  
  	/*
  	 * If needed, fragment the IEs buffer (at IE boundaries) into short
  	 * enough fragments to fit into IW_GENERIC_IE_MAX octet messages.
  	 */
  	pos = ies->data;
  	end = pos + ies->len;
  
  	while (end - pos > IW_GENERIC_IE_MAX) {
  		next = pos + 2 + pos[1];
  		while (next + 2 + next[1] - pos < IW_GENERIC_IE_MAX)
  			next = next + 2 + next[1];
  
  		memset(&iwe, 0, sizeof(iwe));
  		iwe.cmd = IWEVGENIE;
  		iwe.u.data.length = next - pos;
  		current_ev = iwe_stream_add_point_check(info, current_ev,
  							end_buf, &iwe,
  							(void *)pos);
  		if (IS_ERR(current_ev))
  			return current_ev;
  		pos = next;
  	}
  
  	if (end > pos) {
  		memset(&iwe, 0, sizeof(iwe));
  		iwe.cmd = IWEVGENIE;
  		iwe.u.data.length = end - pos;
  		current_ev = iwe_stream_add_point_check(info, current_ev,
  							end_buf, &iwe,
  							(void *)pos);
  		if (IS_ERR(current_ev))
  			return current_ev;
  	}
  
  	return current_ev;
  }
  
  static char *
  ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
  	      struct cfg80211_internal_bss *bss, char *current_ev,
  	      char *end_buf)
  {
  	const struct cfg80211_bss_ies *ies;
  	struct iw_event iwe;
  	const u8 *ie;
  	u8 buf[50];
  	u8 *cfg, *p, *tmp;
  	int rem, i, sig;
  	bool ismesh = false;
  
  	memset(&iwe, 0, sizeof(iwe));
  	iwe.cmd = SIOCGIWAP;
  	iwe.u.ap_addr.sa_family = ARPHRD_ETHER;
  	memcpy(iwe.u.ap_addr.sa_data, bss->pub.bssid, ETH_ALEN);
  	current_ev = iwe_stream_add_event_check(info, current_ev, end_buf, &iwe,
  						IW_EV_ADDR_LEN);
  	if (IS_ERR(current_ev))
  		return current_ev;
  
  	memset(&iwe, 0, sizeof(iwe));
  	iwe.cmd = SIOCGIWFREQ;
  	iwe.u.freq.m = ieee80211_frequency_to_channel(bss->pub.channel->center_freq);
  	iwe.u.freq.e = 0;
  	current_ev = iwe_stream_add_event_check(info, current_ev, end_buf, &iwe,
  						IW_EV_FREQ_LEN);
  	if (IS_ERR(current_ev))
  		return current_ev;
  
  	memset(&iwe, 0, sizeof(iwe));
  	iwe.cmd = SIOCGIWFREQ;
  	iwe.u.freq.m = bss->pub.channel->center_freq;
  	iwe.u.freq.e = 6;
  	current_ev = iwe_stream_add_event_check(info, current_ev, end_buf, &iwe,
  						IW_EV_FREQ_LEN);
  	if (IS_ERR(current_ev))
  		return current_ev;
  
  	if (wiphy->signal_type != CFG80211_SIGNAL_TYPE_NONE) {
  		memset(&iwe, 0, sizeof(iwe));
  		iwe.cmd = IWEVQUAL;
  		iwe.u.qual.updated = IW_QUAL_LEVEL_UPDATED |
  				     IW_QUAL_NOISE_INVALID |
  				     IW_QUAL_QUAL_UPDATED;
  		switch (wiphy->signal_type) {
  		case CFG80211_SIGNAL_TYPE_MBM:
  			sig = bss->pub.signal / 100;
  			iwe.u.qual.level = sig;
  			iwe.u.qual.updated |= IW_QUAL_DBM;
  			if (sig < -110)		/* rather bad */
  				sig = -110;
  			else if (sig > -40)	/* perfect */
  				sig = -40;
  			/* will give a range of 0 .. 70 */
  			iwe.u.qual.qual = sig + 110;
  			break;
  		case CFG80211_SIGNAL_TYPE_UNSPEC:
  			iwe.u.qual.level = bss->pub.signal;
  			/* will give range 0 .. 100 */
  			iwe.u.qual.qual = bss->pub.signal;
  			break;
  		default:
  			/* not reached */
  			break;
  		}
  		current_ev = iwe_stream_add_event_check(info, current_ev,
  							end_buf, &iwe,
  							IW_EV_QUAL_LEN);
  		if (IS_ERR(current_ev))
  			return current_ev;
  	}
  
  	memset(&iwe, 0, sizeof(iwe));
  	iwe.cmd = SIOCGIWENCODE;
  	if (bss->pub.capability & WLAN_CAPABILITY_PRIVACY)
  		iwe.u.data.flags = IW_ENCODE_ENABLED | IW_ENCODE_NOKEY;
  	else
  		iwe.u.data.flags = IW_ENCODE_DISABLED;
  	iwe.u.data.length = 0;
  	current_ev = iwe_stream_add_point_check(info, current_ev, end_buf,
  						&iwe, "");
  	if (IS_ERR(current_ev))
  		return current_ev;
  
  	rcu_read_lock();
  	ies = rcu_dereference(bss->pub.ies);
  	rem = ies->len;
  	ie = ies->data;
  
  	while (rem >= 2) {
  		/* invalid data */
  		if (ie[1] > rem - 2)
  			break;
  
  		switch (ie[0]) {
  		case WLAN_EID_SSID:
  			memset(&iwe, 0, sizeof(iwe));
  			iwe.cmd = SIOCGIWESSID;
  			iwe.u.data.length = ie[1];
  			iwe.u.data.flags = 1;
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf, &iwe,
  								(u8 *)ie + 2);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			break;
  		case WLAN_EID_MESH_ID:
  			memset(&iwe, 0, sizeof(iwe));
  			iwe.cmd = SIOCGIWESSID;
  			iwe.u.data.length = ie[1];
  			iwe.u.data.flags = 1;
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf, &iwe,
  								(u8 *)ie + 2);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			break;
  		case WLAN_EID_MESH_CONFIG:
  			ismesh = true;
  			if (ie[1] != sizeof(struct ieee80211_meshconf_ie))
  				break;
  			cfg = (u8 *)ie + 2;
  			memset(&iwe, 0, sizeof(iwe));
  			iwe.cmd = IWEVCUSTOM;
  			sprintf(buf, "Mesh Network Path Selection Protocol ID: "
  				"0x%02X", cfg[0]);
  			iwe.u.data.length = strlen(buf);
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf,
  								&iwe, buf);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			sprintf(buf, "Path Selection Metric ID: 0x%02X",
  				cfg[1]);
  			iwe.u.data.length = strlen(buf);
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf,
  								&iwe, buf);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			sprintf(buf, "Congestion Control Mode ID: 0x%02X",
  				cfg[2]);
  			iwe.u.data.length = strlen(buf);
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf,
  								&iwe, buf);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			sprintf(buf, "Synchronization ID: 0x%02X", cfg[3]);
  			iwe.u.data.length = strlen(buf);
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf,
  								&iwe, buf);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			sprintf(buf, "Authentication ID: 0x%02X", cfg[4]);
  			iwe.u.data.length = strlen(buf);
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf,
  								&iwe, buf);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			sprintf(buf, "Formation Info: 0x%02X", cfg[5]);
  			iwe.u.data.length = strlen(buf);
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf,
  								&iwe, buf);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			sprintf(buf, "Capabilities: 0x%02X", cfg[6]);
  			iwe.u.data.length = strlen(buf);
  			current_ev = iwe_stream_add_point_check(info,
  								current_ev,
  								end_buf,
  								&iwe, buf);
  			if (IS_ERR(current_ev))
  				goto unlock;
  			break;
  		case WLAN_EID_SUPP_RATES:
  		case WLAN_EID_EXT_SUPP_RATES:
  			/* display all supported rates in readable format */
  			p = current_ev + iwe_stream_lcp_len(info);
  
  			memset(&iwe, 0, sizeof(iwe));
  			iwe.cmd = SIOCGIWRATE;
  			/* Those two flags are ignored... */
  			iwe.u.bitrate.fixed = iwe.u.bitrate.disabled = 0;
  
  			for (i = 0; i < ie[1]; i++) {
  				iwe.u.bitrate.value =
  					((ie[i + 2] & 0x7f) * 500000);
  				tmp = p;
  				p = iwe_stream_add_value(info, current_ev, p,
  							 end_buf, &iwe,
  							 IW_EV_PARAM_LEN);
  				if (p == tmp) {
  					current_ev = ERR_PTR(-E2BIG);
  					goto unlock;
  				}
  			}
  			current_ev = p;
  			break;
  		}
  		rem -= ie[1] + 2;
  		ie += ie[1] + 2;
  	}
  
  	if (bss->pub.capability & (WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS) ||
  	    ismesh) {
  		memset(&iwe, 0, sizeof(iwe));
  		iwe.cmd = SIOCGIWMODE;
  		if (ismesh)
  			iwe.u.mode = IW_MODE_MESH;
  		else if (bss->pub.capability & WLAN_CAPABILITY_ESS)
  			iwe.u.mode = IW_MODE_MASTER;
  		else
  			iwe.u.mode = IW_MODE_ADHOC;
  		current_ev = iwe_stream_add_event_check(info, current_ev,
  							end_buf, &iwe,
  							IW_EV_UINT_LEN);
  		if (IS_ERR(current_ev))
  			goto unlock;
  	}
  
  	memset(&iwe, 0, sizeof(iwe));
  	iwe.cmd = IWEVCUSTOM;
  	sprintf(buf, "tsf=%016llx", (unsigned long long)(ies->tsf));
  	iwe.u.data.length = strlen(buf);
  	current_ev = iwe_stream_add_point_check(info, current_ev, end_buf,
  						&iwe, buf);
  	if (IS_ERR(current_ev))
  		goto unlock;
  	memset(&iwe, 0, sizeof(iwe));
  	iwe.cmd = IWEVCUSTOM;
  	sprintf(buf, " Last beacon: %ums ago",
  		elapsed_jiffies_msecs(bss->ts));
  	iwe.u.data.length = strlen(buf);
  	current_ev = iwe_stream_add_point_check(info, current_ev,
  						end_buf, &iwe, buf);
  	if (IS_ERR(current_ev))
  		goto unlock;
  
  	current_ev = ieee80211_scan_add_ies(info, ies, current_ev, end_buf);
  
   unlock:
  	rcu_read_unlock();
  	return current_ev;
  }
  
  
  static int ieee80211_scan_results(struct cfg80211_registered_device *rdev,
  				  struct iw_request_info *info,
  				  char *buf, size_t len)
  {
  	char *current_ev = buf;
  	char *end_buf = buf + len;
  	struct cfg80211_internal_bss *bss;
  	int err = 0;
  
  	spin_lock_bh(&rdev->bss_lock);
  	cfg80211_bss_expire(rdev);
  
  	list_for_each_entry(bss, &rdev->bss_list, list) {
  		if (buf + len - current_ev <= IW_EV_ADDR_LEN) {
  			err = -E2BIG;
  			break;
  		}
  		current_ev = ieee80211_bss(&rdev->wiphy, info, bss,
  					   current_ev, end_buf);
  		if (IS_ERR(current_ev)) {
  			err = PTR_ERR(current_ev);
  			break;
  		}
  	}
  	spin_unlock_bh(&rdev->bss_lock);
  
  	if (err)
  		return err;
  	return current_ev - buf;
  }
  
  
  int cfg80211_wext_giwscan(struct net_device *dev,
  			  struct iw_request_info *info,
  			  struct iw_point *data, char *extra)
  {
  	struct cfg80211_registered_device *rdev;
  	int res;
  
  	if (!netif_running(dev))
  		return -ENETDOWN;
  
  	rdev = cfg80211_get_dev_from_ifindex(dev_net(dev), dev->ifindex);
  
  	if (IS_ERR(rdev))
  		return PTR_ERR(rdev);
  
  	if (rdev->scan_req || rdev->scan_msg)
  		return -EAGAIN;
  
  	res = ieee80211_scan_results(rdev, info, extra, data->length);
  	data->length = 0;
  	if (res >= 0) {
  		data->length = res;
  		res = 0;
  	}
  
  	return res;
  }
  EXPORT_WEXT_HANDLER(cfg80211_wext_giwscan);
  #endif
  