/*
 * cfg80211 scan result handling
 *
 * Copyright 2008 Johannes Berg <johannes@sipsolutions.net>
 */
#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"

#define IEEE80211_SCAN_RESULT_EXPIRE    (30 * HZ)

void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev, bool leak)
{
        struct cfg80211_scan_request *request;
        struct wireless_dev *wdev;
#ifdef CONFIG_CFG80211_WEXT
        union iwreq_data wrqu;
#endif

        ASSERT_RDEV_LOCK(rdev);

        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->aborted)
                nl80211_send_scan_aborted(rdev, wdev);
        else
                nl80211_send_scan_done(rdev, wdev);

#ifdef CONFIG_CFG80211_WEXT
        if (wdev->netdev && !request->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;

        /*
         * OK. If this is invoked with "leak" then we can't
         * free this ... but we've cleaned it up anyway. The
         * driver failed to call the scan_done callback, so
         * all bets are off, it might still be trying to use
         * the scan request or not ... if it accesses the dev
         * in there (it shouldn't anyway) then it may crash.
         */
        if (!leak)
                kfree(request);
}

void __cfg80211_scan_done(struct work_struct *wk)
{
        struct cfg80211_registered_device *rdev;

        rdev = container_of(wk, struct cfg80211_registered_device,
                            scan_done_wk);

        cfg80211_lock_rdev(rdev);
        ___cfg80211_scan_done(rdev, false);
        cfg80211_unlock_rdev(rdev);
}

void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted)
{
        WARN_ON(request != wiphy_to_dev(request->wiphy)->scan_req);

        request->aborted = aborted;
        queue_work(cfg80211_wq, &wiphy_to_dev(request->wiphy)->scan_done_wk);
}
EXPORT_SYMBOL(cfg80211_scan_done);

void __cfg80211_sched_scan_results(struct work_struct *wk)
{
        struct cfg80211_registered_device *rdev;

        rdev = container_of(wk, struct cfg80211_registered_device,
                            sched_scan_results_wk);

        mutex_lock(&rdev->sched_scan_mtx);

        /* we don't have sched_scan_req anymore if the scan is stopping */
        if (rdev->sched_scan_req)
                nl80211_send_sched_scan_results(rdev,
                                                rdev->sched_scan_req->dev);

        mutex_unlock(&rdev->sched_scan_mtx);
}

void cfg80211_sched_scan_results(struct wiphy *wiphy)
{
        /* ignore if we're not scanning */
        if (wiphy_to_dev(wiphy)->sched_scan_req)
                queue_work(cfg80211_wq,
                           &wiphy_to_dev(wiphy)->sched_scan_results_wk);
}
EXPORT_SYMBOL(cfg80211_sched_scan_results);

void cfg80211_sched_scan_stopped(struct wiphy *wiphy)
{
        struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);

        mutex_lock(&rdev->sched_scan_mtx);
        __cfg80211_stop_sched_scan(rdev, true);
        mutex_unlock(&rdev->sched_scan_mtx);
}
EXPORT_SYMBOL(cfg80211_sched_scan_stopped);

int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
                               bool driver_initiated)
{
        struct net_device *dev;

        lockdep_assert_held(&rdev->sched_scan_mtx);

        if (!rdev->sched_scan_req)
                return -ENOENT;

        dev = rdev->sched_scan_req->dev;

        if (!driver_initiated) {
                int err = rdev->ops->sched_scan_stop(&rdev->wiphy, dev);
                if (err)
                        return err;
        }

        nl80211_send_sched_scan(rdev, dev, NL80211_CMD_SCHED_SCAN_STOPPED);

        kfree(rdev->sched_scan_req);
        rdev->sched_scan_req = NULL;

        return 0;
}

static void bss_release(struct kref *ref)
{
        struct cfg80211_internal_bss *bss;

        bss = container_of(ref, struct cfg80211_internal_bss, ref);
        if (bss->pub.free_priv)
                bss->pub.free_priv(&bss->pub);

        if (bss->beacon_ies_allocated)
                kfree(bss->pub.beacon_ies);
        if (bss->proberesp_ies_allocated)
                kfree(bss->pub.proberesp_ies);

        BUG_ON(atomic_read(&bss->hold));

        kfree(bss);
}

/* must hold dev->bss_lock! */
void cfg80211_bss_age(struct cfg80211_registered_device *dev,
                      unsigned long age_secs)
{
        struct cfg80211_internal_bss *bss;
        unsigned long age_jiffies = msecs_to_jiffies(age_secs * MSEC_PER_SEC);

        list_for_each_entry(bss, &dev->bss_list, list) {
                bss->ts -= age_jiffies;
        }
}

/* must hold dev->bss_lock! */
static void __cfg80211_unlink_bss(struct cfg80211_registered_device *dev,
                                  struct cfg80211_internal_bss *bss)
{
        list_del_init(&bss->list);
        rb_erase(&bss->rbn, &dev->bss_tree);
        kref_put(&bss->ref, bss_release);
}

/* must hold dev->bss_lock! */
void cfg80211_bss_expire(struct cfg80211_registered_device *dev)
{
        struct cfg80211_internal_bss *bss, *tmp;
        bool expired = false;

        list_for_each_entry_safe(bss, tmp, &dev->bss_list, list) {
                if (atomic_read(&bss->hold))
                        continue;
                if (!time_after(jiffies, bss->ts + IEEE80211_SCAN_RESULT_EXPIRE))
                        continue;
                __cfg80211_unlink_bss(dev, bss);
                expired = true;
        }

        if (expired)
                dev->bss_generation++;
}

const u8 *cfg80211_find_ie(u8 eid, const u8 *ies, int len)
{
        while (len > 2 && ies[0] != eid) {
                len -= ies[1] + 2;
                ies += ies[1] + 2;
        }
        if (len < 2)
                return NULL;
        if (len < 2 + ies[1])
                return NULL;
        return ies;
}
EXPORT_SYMBOL(cfg80211_find_ie);

const u8 *cfg80211_find_vendor_ie(unsigned int oui, u8 oui_type,
                                  const u8 *ies, int len)
{
        struct ieee80211_vendor_ie *ie;
        const u8 *pos = ies, *end = ies + len;
        int ie_oui;

        while (pos < end) {
                pos = cfg80211_find_ie(WLAN_EID_VENDOR_SPECIFIC, pos,
                                       end - pos);
                if (!pos)
                        return NULL;

                if (end - pos < sizeof(*ie))
                        return NULL;

                ie = (struct ieee80211_vendor_ie *)pos;
                ie_oui = ie->oui[0] << 16 | ie->oui[1] << 8 | ie->oui[2];
                if (ie_oui == oui && ie->oui_type == oui_type)
                        return pos;

                pos += 2 + ie->len;
        }
        return NULL;
}
EXPORT_SYMBOL(cfg80211_find_vendor_ie);

static int cmp_ies(u8 num, u8 *ies1, size_t len1, u8 *ies2, size_t len2)
{
        const u8 *ie1 = cfg80211_find_ie(num, ies1, len1);
        const u8 *ie2 = cfg80211_find_ie(num, ies2, len2);

        /* equal if both missing */
        if (!ie1 && !ie2)
                return 0;
        /* sort missing IE before (left of) present IE */
        if (!ie1)
                return -1;
        if (!ie2)
                return 1;

        /* 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]);
}

static bool is_bss(struct cfg80211_bss *a,
                   const u8 *bssid,
                   const u8 *ssid, size_t ssid_len)
{
        const u8 *ssidie;

        if (bssid && !ether_addr_equal(a->bssid, bssid))
                return false;

        if (!ssid)
                return true;

        ssidie = cfg80211_find_ie(WLAN_EID_SSID,
                                  a->information_elements,
                                  a->len_information_elements);
        if (!ssidie)
                return false;
        if (ssidie[1] != ssid_len)
                return false;
        return memcmp(ssidie + 2, ssid, ssid_len) == 0;
}

static bool is_mesh_bss(struct cfg80211_bss *a)
{
        const u8 *ie;

        if (!WLAN_CAPABILITY_IS_STA_BSS(a->capability))
                return false;

        ie = cfg80211_find_ie(WLAN_EID_MESH_ID,
                              a->information_elements,
                              a->len_information_elements);
        if (!ie)
                return false;

        ie = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                              a->information_elements,
                              a->len_information_elements);
        if (!ie)
                return false;

        return true;
}

static bool is_mesh(struct cfg80211_bss *a,
                    const u8 *meshid, size_t meshidlen,
                    const u8 *meshcfg)
{
        const u8 *ie;

        if (!WLAN_CAPABILITY_IS_STA_BSS(a->capability))
                return false;

        ie = cfg80211_find_ie(WLAN_EID_MESH_ID,
                              a->information_elements,
                              a->len_information_elements);
        if (!ie)
                return false;
        if (ie[1] != meshidlen)
                return false;
        if (memcmp(ie + 2, meshid, meshidlen))
                return false;

        ie = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                              a->information_elements,
                              a->len_information_elements);
        if (!ie)
                return false;
        if (ie[1] != sizeof(struct ieee80211_meshconf_ie))
                return false;

        /*
         * Ignore mesh capability (last two bytes of the IE) when
         * comparing since that may differ between stations taking
         * part in the same mesh.
         */
        return memcmp(ie + 2, meshcfg,
            sizeof(struct ieee80211_meshconf_ie) - 2) == 0;
}

static int cmp_bss_core(struct cfg80211_bss *a,
                        struct cfg80211_bss *b)
{
        int r;

        if (a->channel != b->channel)
                return b->channel->center_freq - a->channel->center_freq;

        if (is_mesh_bss(a) && is_mesh_bss(b)) {
                r = cmp_ies(WLAN_EID_MESH_ID,
                            a->information_elements,
                            a->len_information_elements,
                            b->information_elements,
                            b->len_information_elements);
                if (r)
                        return r;
                return cmp_ies(WLAN_EID_MESH_CONFIG,
                               a->information_elements,
                               a->len_information_elements,
                               b->information_elements,
                               b->len_information_elements);
        }

        /*
         * we can't use compare_ether_addr here since we need a < > operator.
         * The binary return value of compare_ether_addr isn't enough
         */
        return memcmp(a->bssid, b->bssid, sizeof(a->bssid));
}

static int cmp_bss(struct cfg80211_bss *a,
                   struct cfg80211_bss *b)
{
        int r;

        r = cmp_bss_core(a, b);
        if (r)
                return r;

        return cmp_ies(WLAN_EID_SSID,
                       a->information_elements,
                       a->len_information_elements,
                       b->information_elements,
                       b->len_information_elements);
}

static int cmp_hidden_bss(struct cfg80211_bss *a,
                   struct cfg80211_bss *b)
{
        const u8 *ie1;
        const u8 *ie2;
        int i;
        int r;

        r = cmp_bss_core(a, b);
        if (r)
                return r;

        ie1 = cfg80211_find_ie(WLAN_EID_SSID,
                        a->information_elements,
                        a->len_information_elements);
        ie2 = cfg80211_find_ie(WLAN_EID_SSID,
                        b->information_elements,
                        b->len_information_elements);

        /* Key comparator must use same algorithm in any rb-tree
         * search function (order is important), otherwise ordering
         * of items in the tree is broken and search gives incorrect
         * results. This code uses same order as cmp_ies() does. */

        /* sort missing IE before (left of) present IE */
        if (!ie1)
                return -1;
        if (!ie2)
                return 1;

        /* zero-size SSID is used as an indication of the hidden bss */
        if (!ie2[1])
                return 0;

        /* sort by length first, then by contents */
        if (ie1[1] != ie2[1])
                return ie2[1] - ie1[1];

        /* zeroed SSID ie is another indication of a hidden bss */
        for (i = 0; i < ie2[1]; i++)
                if (ie2[i + 2])
                        return -1;

        return 0;
}

struct cfg80211_bss *cfg80211_get_bss(struct wiphy *wiphy,
                                      struct ieee80211_channel *channel,
                                      const u8 *bssid,
                                      const u8 *ssid, size_t ssid_len,
                                      u16 capa_mask, u16 capa_val)
{
        struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
        struct cfg80211_internal_bss *bss, *res = NULL;
        unsigned long now = jiffies;

        spin_lock_bh(&dev->bss_lock);

        list_for_each_entry(bss, &dev->bss_list, list) {
                if ((bss->pub.capability & capa_mask) != capa_val)
                        continue;
                if (channel && bss->pub.channel != channel)
                        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;
                        kref_get(&res->ref);
                        break;
                }
        }

        spin_unlock_bh(&dev->bss_lock);
        if (!res)
                return NULL;
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_get_bss);

struct cfg80211_bss *cfg80211_get_mesh(struct wiphy *wiphy,
                                       struct ieee80211_channel *channel,
                                       const u8 *meshid, size_t meshidlen,
                                       const u8 *meshcfg)
{
        struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
        struct cfg80211_internal_bss *bss, *res = NULL;

        spin_lock_bh(&dev->bss_lock);

        list_for_each_entry(bss, &dev->bss_list, list) {
                if (channel && bss->pub.channel != channel)
                        continue;
                if (is_mesh(&bss->pub, meshid, meshidlen, meshcfg)) {
                        res = bss;
                        kref_get(&res->ref);
                        break;
                }
        }

        spin_unlock_bh(&dev->bss_lock);
        if (!res)
                return NULL;
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_get_mesh);


static void rb_insert_bss(struct cfg80211_registered_device *dev,
                          struct cfg80211_internal_bss *bss)
{
        struct rb_node **p = &dev->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);

                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, &dev->bss_tree);
}

static struct cfg80211_internal_bss *
rb_find_bss(struct cfg80211_registered_device *dev,
            struct cfg80211_internal_bss *res)
{
        struct rb_node *n = dev->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);

                if (r == 0)
                        return bss;
                else if (r < 0)
                        n = n->rb_left;
                else
                        n = n->rb_right;
        }

        return NULL;
}

static struct cfg80211_internal_bss *
rb_find_hidden_bss(struct cfg80211_registered_device *dev,
            struct cfg80211_internal_bss *res)
{
        struct rb_node *n = dev->bss_tree.rb_node;
        struct cfg80211_internal_bss *bss;
        int r;

        while (n) {
                bss = rb_entry(n, struct cfg80211_internal_bss, rbn);
                r = cmp_hidden_bss(&res->pub, &bss->pub);

                if (r == 0)
                        return bss;
                else if (r < 0)
                        n = n->rb_left;
                else
                        n = n->rb_right;
        }

        return NULL;
}

static void
copy_hidden_ies(struct cfg80211_internal_bss *res,
                 struct cfg80211_internal_bss *hidden)
{
        if (unlikely(res->pub.beacon_ies))
                return;
        if (WARN_ON(!hidden->pub.beacon_ies))
                return;

        res->pub.beacon_ies = kmalloc(hidden->pub.len_beacon_ies, GFP_ATOMIC);
        if (unlikely(!res->pub.beacon_ies))
                return;

        res->beacon_ies_allocated = true;
        res->pub.len_beacon_ies = hidden->pub.len_beacon_ies;
        memcpy(res->pub.beacon_ies, hidden->pub.beacon_ies,
                        res->pub.len_beacon_ies);
}

static struct cfg80211_internal_bss *
cfg80211_bss_update(struct cfg80211_registered_device *dev,
                    struct cfg80211_internal_bss *res)
{
        struct cfg80211_internal_bss *found = NULL;

        /*
         * The reference to "res" is donated to this function.
         */

        if (WARN_ON(!res->pub.channel)) {
                kref_put(&res->ref, bss_release);
                return NULL;
        }

        res->ts = jiffies;

        spin_lock_bh(&dev->bss_lock);

        found = rb_find_bss(dev, res);

        if (found) {
                found->pub.beacon_interval = res->pub.beacon_interval;
                found->pub.tsf = res->pub.tsf;
                found->pub.signal = res->pub.signal;
                found->pub.capability = res->pub.capability;
                found->ts = res->ts;

                /* Update IEs */
                if (res->pub.proberesp_ies) {
                        size_t used = dev->wiphy.bss_priv_size + sizeof(*res);
                        size_t ielen = res->pub.len_proberesp_ies;

                        if (found->pub.proberesp_ies &&
                            !found->proberesp_ies_allocated &&
                            ksize(found) >= used + ielen) {
                                memcpy(found->pub.proberesp_ies,
                                       res->pub.proberesp_ies, ielen);
                                found->pub.len_proberesp_ies = ielen;
                        } else {
                                u8 *ies = found->pub.proberesp_ies;

                                if (found->proberesp_ies_allocated)
                                        ies = krealloc(ies, ielen, GFP_ATOMIC);
                                else
                                        ies = kmalloc(ielen, GFP_ATOMIC);

                                if (ies) {
                                        memcpy(ies, res->pub.proberesp_ies,
                                               ielen);
                                        found->proberesp_ies_allocated = true;
                                        found->pub.proberesp_ies = ies;
                                        found->pub.len_proberesp_ies = ielen;
                                }
                        }

                        /* Override possible earlier Beacon frame IEs */
                        found->pub.information_elements =
                                found->pub.proberesp_ies;
                        found->pub.len_information_elements =
                                found->pub.len_proberesp_ies;
                }
                if (res->pub.beacon_ies) {
                        size_t used = dev->wiphy.bss_priv_size + sizeof(*res);
                        size_t ielen = res->pub.len_beacon_ies;
                        bool information_elements_is_beacon_ies =
                                (found->pub.information_elements ==
                                 found->pub.beacon_ies);

                        if (found->pub.beacon_ies &&
                            !found->beacon_ies_allocated &&
                            ksize(found) >= used + ielen) {
                                memcpy(found->pub.beacon_ies,
                                       res->pub.beacon_ies, ielen);
                                found->pub.len_beacon_ies = ielen;
                        } else {
                                u8 *ies = found->pub.beacon_ies;

                                if (found->beacon_ies_allocated)
                                        ies = krealloc(ies, ielen, GFP_ATOMIC);
                                else
                                        ies = kmalloc(ielen, GFP_ATOMIC);

                                if (ies) {
                                        memcpy(ies, res->pub.beacon_ies,
                                               ielen);
                                        found->beacon_ies_allocated = true;
                                        found->pub.beacon_ies = ies;
                                        found->pub.len_beacon_ies = ielen;
                                }
                        }

                        /* Override IEs if they were from a beacon before */
                        if (information_elements_is_beacon_ies) {
                                found->pub.information_elements =
                                        found->pub.beacon_ies;
                                found->pub.len_information_elements =
                                        found->pub.len_beacon_ies;
                        }
                }

                kref_put(&res->ref, bss_release);
        } else {
                struct cfg80211_internal_bss *hidden;

                /* First check if the beacon is a probe response from
                 * a hidden bss. If so, copy beacon ies (with nullified
                 * ssid) into the probe response bss entry (with real ssid).
                 * It is required basically for PSM implementation
                 * (probe responses do not contain tim ie) */

                /* TODO: The code is not trying to update existing probe
                 * response bss entries when beacon ies are
                 * getting changed. */
                hidden = rb_find_hidden_bss(dev, res);
                if (hidden)
                        copy_hidden_ies(res, hidden);

                /* this "consumes" the reference */
                list_add_tail(&res->list, &dev->bss_list);
                rb_insert_bss(dev, res);
                found = res;
        }

        dev->bss_generation++;
        spin_unlock_bh(&dev->bss_lock);

        kref_get(&found->ref);
        return found;
}

struct cfg80211_bss*
cfg80211_inform_bss(struct wiphy *wiphy,
                    struct ieee80211_channel *channel,
                    const u8 *bssid, u64 tsf, u16 capability,
                    u16 beacon_interval, const u8 *ie, size_t ielen,
                    s32 signal, gfp_t gfp)
{
        struct cfg80211_internal_bss *res;
        size_t privsz;

        if (WARN_ON(!wiphy))
                return NULL;

        privsz = wiphy->bss_priv_size;

        if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
                        (signal < 0 || signal > 100)))
                return NULL;

        res = kzalloc(sizeof(*res) + privsz + ielen, gfp);
        if (!res)
                return NULL;

        memcpy(res->pub.bssid, bssid, ETH_ALEN);
        res->pub.channel = channel;
        res->pub.signal = signal;
        res->pub.tsf = tsf;
        res->pub.beacon_interval = beacon_interval;
        res->pub.capability = capability;
        /*
         * Since 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 information_elements pointer should we have received an
         * earlier indication of Probe Response data.
         *
         * The initial buffer for the IEs is allocated with the BSS entry and
         * is located after the private area.
         */
        res->pub.beacon_ies = (u8 *)res + sizeof(*res) + privsz;
        memcpy(res->pub.beacon_ies, ie, ielen);
        res->pub.len_beacon_ies = ielen;
        res->pub.information_elements = res->pub.beacon_ies;
        res->pub.len_information_elements = res->pub.len_beacon_ies;

        kref_init(&res->ref);

        res = cfg80211_bss_update(wiphy_to_dev(wiphy), res);
        if (!res)
                return NULL;

        if (res->pub.capability & WLAN_CAPABILITY_ESS)
                regulatory_hint_found_beacon(wiphy, channel, gfp);

        /* cfg80211_bss_update gives us a referenced result */
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss);

struct cfg80211_bss *
cfg80211_inform_bss_frame(struct wiphy *wiphy,
                          struct ieee80211_channel *channel,
                          struct ieee80211_mgmt *mgmt, size_t len,
                          s32 signal, gfp_t gfp)
{
        struct cfg80211_internal_bss *res;
        size_t ielen = len - offsetof(struct ieee80211_mgmt,
                                      u.probe_resp.variable);
        size_t privsz;

        if (WARN_ON(!mgmt))
                return NULL;

        if (WARN_ON(!wiphy))
                return NULL;

        if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
                    (signal < 0 || signal > 100)))
                return NULL;

        if (WARN_ON(len < offsetof(struct ieee80211_mgmt, u.probe_resp.variable)))
                return NULL;

        privsz = wiphy->bss_priv_size;

        res = kzalloc(sizeof(*res) + privsz + ielen, gfp);
        if (!res)
                return NULL;

        memcpy(res->pub.bssid, mgmt->bssid, ETH_ALEN);
        res->pub.channel = channel;
        res->pub.signal = signal;
        res->pub.tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
        res->pub.beacon_interval = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
        res->pub.capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);
        /*
         * The initial buffer for the IEs is allocated with the BSS entry and
         * is located after the private area.
         */
        if (ieee80211_is_probe_resp(mgmt->frame_control)) {
                res->pub.proberesp_ies = (u8 *) res + sizeof(*res) + privsz;
                memcpy(res->pub.proberesp_ies, mgmt->u.probe_resp.variable,
                       ielen);
                res->pub.len_proberesp_ies = ielen;
                res->pub.information_elements = res->pub.proberesp_ies;
                res->pub.len_information_elements = res->pub.len_proberesp_ies;
        } else {
                res->pub.beacon_ies = (u8 *) res + sizeof(*res) + privsz;
                memcpy(res->pub.beacon_ies, mgmt->u.beacon.variable, ielen);
                res->pub.len_beacon_ies = ielen;
                res->pub.information_elements = res->pub.beacon_ies;
                res->pub.len_information_elements = res->pub.len_beacon_ies;
        }

        kref_init(&res->ref);

        res = cfg80211_bss_update(wiphy_to_dev(wiphy), res);
        if (!res)
                return NULL;

        if (res->pub.capability & WLAN_CAPABILITY_ESS)
                regulatory_hint_found_beacon(wiphy, channel, gfp);

        /* cfg80211_bss_update gives us a referenced result */
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss_frame);

void cfg80211_ref_bss(struct cfg80211_bss *pub)
{
        struct cfg80211_internal_bss *bss;

        if (!pub)
                return;

        bss = container_of(pub, struct cfg80211_internal_bss, pub);
        kref_get(&bss->ref);
}
EXPORT_SYMBOL(cfg80211_ref_bss);

void cfg80211_put_bss(struct cfg80211_bss *pub)
{
        struct cfg80211_internal_bss *bss;

        if (!pub)
                return;

        bss = container_of(pub, struct cfg80211_internal_bss, pub);
        kref_put(&bss->ref, bss_release);
}
EXPORT_SYMBOL(cfg80211_put_bss);

void cfg80211_unlink_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
{
        struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
        struct cfg80211_internal_bss *bss;

        if (WARN_ON(!pub))
                return;

        bss = container_of(pub, struct cfg80211_internal_bss, pub);

        spin_lock_bh(&dev->bss_lock);
        if (!list_empty(&bss->list)) {
                __cfg80211_unlink_bss(dev, bss);
                dev->bss_generation++;
        }
        spin_unlock_bh(&dev->bss_lock);
}
EXPORT_SYMBOL(cfg80211_unlink_bss);

#ifdef CONFIG_CFG80211_WEXT
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 ieee80211_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) {
                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 {
                for (band = 0; band < IEEE80211_NUM_BANDS; band++)
                        if (wiphy->bands[band])
                                n_channels += wiphy->bands[band]->n_channels;
        }

        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;

        /* translate "Scan on frequencies" request */
        i = 0;
        for (band = 0; band < IEEE80211_NUM_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++) {
                                        int wext_freq = cfg80211_wext_freq(wiphy, &wreq->channel_list[k]);
                                        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 < IEEE80211_NUM_BANDS; i++)
                if (wiphy->bands[i])
                        creq->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;

        rdev->scan_req = creq;
        err = rdev->ops->scan(wiphy, 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);
        cfg80211_unlock_rdev(rdev);
        return err;
}
EXPORT_SYMBOL_GPL(cfg80211_wext_siwscan);

static void ieee80211_scan_add_ies(struct iw_request_info *info,
                                   struct cfg80211_bss *bss,
                                   char **current_ev, char *end_buf)
{
        u8 *pos, *end, *next;
        struct iw_event iwe;

        if (!bss->information_elements ||
            !bss->len_information_elements)
                return;

        /*
         * If needed, fragment the IEs buffer (at IE boundaries) into short
         * enough fragments to fit into IW_GENERIC_IE_MAX octet messages.
         */
        pos = bss->information_elements;
        end = pos + bss->len_information_elements;

        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(info, *current_ev,
                                                   end_buf, &iwe, pos);

                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(info, *current_ev,
                                                   end_buf, &iwe, pos);
        }
}

static inline unsigned int elapsed_jiffies_msecs(unsigned long start)
{
        unsigned long end = jiffies;

        if (end >= start)
                return jiffies_to_msecs(end - start);

        return jiffies_to_msecs(end + (MAX_JIFFY_OFFSET - start) + 1);
}

static char *
ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
              struct cfg80211_internal_bss *bss, char *current_ev,
              char *end_buf)
{
        struct iw_event iwe;
        u8 *buf, *cfg, *p;
        u8 *ie = bss->pub.information_elements;
        int rem = bss->pub.len_information_elements, 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(info, current_ev, end_buf, &iwe,
                                          IW_EV_ADDR_LEN);

        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(info, current_ev, end_buf, &iwe,
                                          IW_EV_FREQ_LEN);

        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(info, current_ev, end_buf, &iwe,
                                          IW_EV_FREQ_LEN);

        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(info, current_ev, end_buf,
                                                  &iwe, IW_EV_QUAL_LEN);
        }

        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(info, current_ev, end_buf,
                                          &iwe, "");

        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(info, current_ev, end_buf,
                                                          &iwe, ie + 2);
                        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(info, current_ev, end_buf,
                                                          &iwe, ie + 2);
                        break;
                case WLAN_EID_MESH_CONFIG:
                        ismesh = true;
                        if (ie[1] != sizeof(struct ieee80211_meshconf_ie))
                                break;
                        buf = kmalloc(50, GFP_ATOMIC);
                        if (!buf)
                                break;
                        cfg = 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(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Path Selection Metric ID: 0x%02X",
                                cfg[1]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Congestion Control Mode ID: 0x%02X",
                                cfg[2]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Synchronization ID: 0x%02X", cfg[3]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Authentication ID: 0x%02X", cfg[4]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Formation Info: 0x%02X", cfg[5]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Capabilities: 0x%02X", cfg[6]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        kfree(buf);
                        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);
                                p = iwe_stream_add_value(info, current_ev, p,
                                                end_buf, &iwe, IW_EV_PARAM_LEN);
                        }
                        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(info, current_ev, end_buf,
                                                  &iwe, IW_EV_UINT_LEN);
        }

        buf = kmalloc(30, GFP_ATOMIC);
        if (buf) {
                memset(&iwe, 0, sizeof(iwe));
                iwe.cmd = IWEVCUSTOM;
                sprintf(buf, "tsf=%016llx", (unsigned long long)(bss->pub.tsf));
                iwe.u.data.length = strlen(buf);
                current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                                                  &iwe, buf);
                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(info, current_ev,
                                                  end_buf, &iwe, buf);
                kfree(buf);
        }

        ieee80211_scan_add_ies(info, &bss->pub, &current_ev, end_buf);

        return current_ev;
}


static int ieee80211_scan_results(struct cfg80211_registered_device *dev,
                                  struct iw_request_info *info,
                                  char *buf, size_t len)
{
        char *current_ev = buf;
        char *end_buf = buf + len;
        struct cfg80211_internal_bss *bss;

        spin_lock_bh(&dev->bss_lock);
        cfg80211_bss_expire(dev);

        list_for_each_entry(bss, &dev->bss_list, list) {
                if (buf + len - current_ev <= IW_EV_ADDR_LEN) {
                        spin_unlock_bh(&dev->bss_lock);
                        return -E2BIG;
                }
                current_ev = ieee80211_bss(&dev->wiphy, info, bss,
                                           current_ev, end_buf);
        }
        spin_unlock_bh(&dev->bss_lock);
        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) {
                res = -EAGAIN;
                goto out;
        }

        res = ieee80211_scan_results(rdev, info, extra, data->length);
        data->length = 0;
        if (res >= 0) {
                data->length = res;
                res = 0;
        }

 out:
        cfg80211_unlock_rdev(rdev);
        return res;
}
EXPORT_SYMBOL_GPL(cfg80211_wext_giwscan);
#endif