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madwifi/net80211/ieee80211_scan.c

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/*-
* Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id$
*/
#ifndef EXPORT_SYMTAB
#define EXPORT_SYMTAB
#endif
/*
* IEEE 802.11 scanning support.
*/
#if !defined(AUTOCONF_INCLUDED) && !defined(CONFIG_LOCALVERSION)
#include <linux/config.h>
#endif
#include <linux/version.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include "if_media.h"
#include <net80211/ieee80211_var.h>
#include <net80211/if_athproto.h>
struct scan_state {
struct ieee80211_scan_state base; /* public state */
u_int ss_iflags; /* flags used internally */
#define ISCAN_MINDWELL 0x0001 /* min dwell time reached */
#define ISCAN_DISCARD 0x0002 /* discard rx'd frames */
#define ISCAN_CANCEL 0x0004 /* cancel current scan */
#define ISCAN_START 0x0008 /* 1st time through next_scan */
unsigned long ss_chanmindwell; /* min dwell on curchan */
unsigned long ss_scanend; /* time scan must stop */
u_int ss_duration; /* duration for next scan */
struct tasklet_struct ss_pwrsav; /* sta ps ena tasklet */
struct timer_list ss_scan_timer; /* scan timer */
};
#define SCAN_PRIVATE(_ss) ((struct scan_state *)(_ss))
/*
* Amount of time to go off-channel during a background
* scan. This value should be large enough to catch most
* APs but short enough that we can return on-channel
* before our listen interval expires.
*
* XXX tunable
* XXX check against configured listen interval
*/
#define IEEE80211_SCAN_OFFCHANNEL msecs_to_jiffies(150)
/*
* Roaming-related defaults. RSSI thresholds are as returned by the
* driver (dBm). Transmit rate thresholds are IEEE rate codes (i.e
* .5M units).
*/
#define SCAN_VALID_DEFAULT 60 /* scan cache valid age (secs) */
#define ROAM_RSSI_11A_DEFAULT 9 /* rssi threshold for 11a bss */
#define ROAM_RSSI_11G_DEFAULT 9 /* rssi threshold for 11g bss */
#define ROAM_RSSI_11BONLY_DEFAULT 9 /* rssi threshold for 11b-only bss */
#define ROAM_RATE_11A_DEFAULT 2 * 24 /* tx rate threshold for 11a bss */
#define ROAM_RATE_11G_DEFAULT 2 * 9 /* tx rate threshold for 11g bss */
#define ROAM_RATE_11BONLY_DEFAULT 2 * 5 /* tx rate threshold for 11b-only bss */
static void scan_restart_pwrsav(unsigned long);
static void scan_next(unsigned long);
void
ieee80211_scan_attach(struct ieee80211com *ic)
{
struct scan_state *ss;
ic->ic_roaming = IEEE80211_ROAMING_AUTO;
MALLOC(ss, struct scan_state *, sizeof(struct scan_state),
M_80211_SCAN, M_NOWAIT | M_ZERO);
if (ss != NULL) {
init_timer(&ss->ss_scan_timer);
ss->ss_scan_timer.function = scan_next;
ss->ss_scan_timer.data = (unsigned long) ss;
tasklet_init(&ss->ss_pwrsav, scan_restart_pwrsav,
(unsigned long) ss);
ic->ic_scan = &ss->base;
} else
ic->ic_scan = NULL;
}
void
ieee80211_scan_detach(struct ieee80211com *ic)
{
struct ieee80211_scan_state *ss = ic->ic_scan;
if (ss != NULL) {
del_timer(&SCAN_PRIVATE(ss)->ss_scan_timer);
tasklet_kill(&SCAN_PRIVATE(ss)->ss_pwrsav);
if (ss->ss_ops != NULL) {
ss->ss_ops->scan_detach(ss);
ss->ss_ops = NULL;
}
ic->ic_flags &= ~IEEE80211_F_SCAN;
ic->ic_scan = NULL;
FREE(SCAN_PRIVATE(ss), M_80211_SCAN);
}
}
void
ieee80211_scan_vattach(struct ieee80211vap *vap)
{
vap->iv_bgscanidle = msecs_to_jiffies(IEEE80211_BGSCAN_IDLE_DEFAULT);
vap->iv_bgscanintvl = IEEE80211_BGSCAN_INTVAL_DEFAULT * HZ;
vap->iv_scanvalid = SCAN_VALID_DEFAULT * HZ;
vap->iv_roam.rssi11a = ROAM_RSSI_11A_DEFAULT;
vap->iv_roam.rssi11g = ROAM_RSSI_11G_DEFAULT;
vap->iv_roam.rssi11bOnly = ROAM_RSSI_11BONLY_DEFAULT;
vap->iv_roam.rate11a = ROAM_RATE_11A_DEFAULT;
vap->iv_roam.rate11g = ROAM_RATE_11G_DEFAULT;
vap->iv_roam.rate11bOnly = ROAM_RATE_11BONLY_DEFAULT;
}
void
ieee80211_scan_vdetach(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
IEEE80211_LOCK_IRQ(ic);
if (ss->ss_vap == vap) {
if (ic->ic_flags & IEEE80211_F_SCAN) {
del_timer(&SCAN_PRIVATE(ss)->ss_scan_timer);
ic->ic_flags &= ~IEEE80211_F_SCAN;
}
if (ss->ss_ops != NULL) {
ss->ss_ops->scan_detach(ss);
ss->ss_ops = NULL;
}
}
IEEE80211_UNLOCK_IRQ(ic);
}
/*
* Simple-minded scanner module support.
*/
#define IEEE80211_SCANNER_MAX (IEEE80211_M_MONITOR+1)
static const char *scan_modnames[IEEE80211_SCANNER_MAX] = {
[IEEE80211_M_IBSS] = "wlan_scan_sta",
[IEEE80211_M_STA] = "wlan_scan_sta",
[IEEE80211_M_AHDEMO] = "wlan_scan_sta",
[IEEE80211_M_HOSTAP] = "wlan_scan_ap",
};
static const struct ieee80211_scanner *scanners[IEEE80211_SCANNER_MAX];
/* If try load is set, this function will attempt to automatically load the
* requested module if it is not present. This is on operation that may sleep.
* Therefore:
* if !!tryload, then Context: process
*/
const struct ieee80211_scanner *
ieee80211_scanner_get(enum ieee80211_opmode mode, int tryload)
{
int err;
if (mode >= IEEE80211_SCANNER_MAX)
return NULL;
if (scan_modnames[mode] == NULL)
return NULL;
if (scanners[mode] == NULL && tryload) {
err = ieee80211_load_module(scan_modnames[mode]);
if (scanners[mode] == NULL || err)
printk(KERN_WARNING "unable to load %s\n", scan_modnames[mode]);
}
return scanners[mode];
}
EXPORT_SYMBOL(ieee80211_scanner_get);
void
ieee80211_scanner_register(enum ieee80211_opmode mode,
const struct ieee80211_scanner *scan)
{
if (mode >= IEEE80211_SCANNER_MAX)
return;
scanners[mode] = scan;
}
EXPORT_SYMBOL(ieee80211_scanner_register);
void
ieee80211_scanner_unregister(enum ieee80211_opmode mode,
const struct ieee80211_scanner *scan)
{
if (mode >= IEEE80211_SCANNER_MAX)
return;
if (scanners[mode] == scan)
scanners[mode] = NULL;
}
EXPORT_SYMBOL(ieee80211_scanner_unregister);
void
ieee80211_scanner_unregister_all(const struct ieee80211_scanner *scan)
{
int m;
for (m = 0; m < IEEE80211_SCANNER_MAX; m++)
if (scanners[m] == scan)
scanners[m] = NULL;
}
EXPORT_SYMBOL(ieee80211_scanner_unregister_all);
static void
change_channel(struct ieee80211com *ic,
struct ieee80211_channel *chan)
{
ic->ic_curchan = chan;
ic->ic_set_channel(ic);
}
static char
channel_type(const struct ieee80211_channel *c)
{
if (IEEE80211_IS_CHAN_ST(c))
return 'S';
if (IEEE80211_IS_CHAN_108A(c))
return 'T';
if (IEEE80211_IS_CHAN_108G(c))
return 'G';
if (IEEE80211_IS_CHAN_A(c))
return 'a';
if (IEEE80211_IS_CHAN_ANYG(c))
return 'g';
if (IEEE80211_IS_CHAN_B(c))
return 'b';
return 'f';
}
void
ieee80211_scan_dump_channels(const struct ieee80211_scan_state *ss)
{
struct ieee80211com *ic = ss->ss_vap->iv_ic;
const char *sep;
int i;
sep = "";
for (i = ss->ss_next; i < ss->ss_last; i++) {
const struct ieee80211_channel *c = ss->ss_chans[i];
printk("%s%u%c", sep, ieee80211_chan2ieee(ic, c),
channel_type(c));
sep = ", ";
}
}
EXPORT_SYMBOL(ieee80211_scan_dump_channels);
/*
* Enable station power save mode and start/restart the scanning thread.
*/
static void
scan_restart_pwrsav(unsigned long arg)
{
struct scan_state *ss = (struct scan_state *)arg;
struct ieee80211vap *vap = ss->base.ss_vap;
struct ieee80211com *ic = vap->iv_ic;
int delay;
ieee80211_sta_pwrsave(vap, 1);
/*
* Use an initial 1ms delay to ensure the null
* data frame has a chance to go out.
* XXX: 1ms is a lot, better to trigger scan
* on TX complete.
*/
delay = msecs_to_jiffies(1);
if (delay < 1)
delay = 1;
ic->ic_scan_start(ic); /* notify driver */
ss->ss_scanend = jiffies + delay + ss->ss_duration;
ss->ss_iflags |= ISCAN_START;
mod_timer(&ss->ss_scan_timer, jiffies + delay);
}
/*
* Start/restart scanning. If we're operating in station mode
* and associated notify the ap we're going into power save mode
* and schedule a callback to initiate the work (where there's a
* better context for doing the work). Otherwise, start the scan
* directly.
*/
static int
scan_restart(struct scan_state *ss, u_int duration)
{
struct ieee80211vap *vap = ss->base.ss_vap;
struct ieee80211com *ic = vap->iv_ic;
if (ss->base.ss_next == ss->base.ss_last) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: no channels to scan\n", __func__);
return 0;
} else {
if ((vap->iv_opmode == IEEE80211_M_STA) &&
(vap->iv_state == IEEE80211_S_RUN) &&
!(IEEE80211_VAP_IS_SLEEPING(vap))) {
/*
* Initiate power save before going off-channel.
* Note that we cannot do this directly because
* of locking issues; instead we defer it to a
* tasklet.
*/
ss->ss_duration = duration;
tasklet_schedule(&ss->ss_pwrsav);
} else {
ic->ic_scan_start(ic); /* notify driver */
ss->ss_scanend = jiffies + duration;
ss->ss_iflags |= ISCAN_START;
mod_timer(&ss->ss_scan_timer, jiffies);
}
return 1;
}
}
static void
copy_ssid(struct ieee80211vap *vap, struct ieee80211_scan_state *ss,
int nssid, const struct ieee80211_scan_ssid ssids[])
{
if (nssid > IEEE80211_SCAN_MAX_SSID) {
/* XXX printk */
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: too many ssid %d, ignoring all of them\n",
__func__, nssid);
return;
}
memcpy(ss->ss_ssid, ssids, nssid * sizeof(ssids[0]));
ss->ss_nssid = nssid;
}
/*
* Start a scan unless one is already going.
*/
int
ieee80211_start_scan(struct ieee80211vap *vap, int flags, u_int duration,
u_int nssid, const struct ieee80211_scan_ssid ssids[])
{
struct ieee80211com *ic = vap->iv_ic;
const struct ieee80211_scanner *scan;
struct ieee80211_scan_state *ss = ic->ic_scan;
int scanning;
scan = ieee80211_scanner_get(vap->iv_opmode, 0);
if (scan == NULL) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: no scanner support for mode %u\n",
__func__, vap->iv_opmode);
/* XXX stat */
return 0;
}
IEEE80211_LOCK_IRQ(ic);
if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan, duration %lu, desired mode %s, %s%s%s%s\n",
__func__,
flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
duration,
ieee80211_phymode_name[vap->iv_des_mode],
flags & IEEE80211_SCAN_FLUSH ? "flush" : "append",
flags & IEEE80211_SCAN_NOPICK ? ", nopick" : "",
flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : "",
flags & IEEE80211_SCAN_ONCE ? ", once" : "");
ss->ss_vap = vap;
if (ss->ss_ops != scan) {
/* switch scanners; detach old, attach new */
if (ss->ss_ops != NULL)
ss->ss_ops->scan_detach(ss);
if (!scan->scan_attach(ss)) {
/* XXX attach failure */
/* XXX stat+msg */
ss->ss_ops = NULL;
} else
ss->ss_ops = scan;
}
if (ss->ss_ops != NULL) {
if ((flags & IEEE80211_SCAN_NOSSID) == 0)
copy_ssid(vap, ss, nssid, ssids);
/* NB: top 4 bits for internal use */
ss->ss_flags = flags & 0xfff;
if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
vap->iv_stats.is_scan_active++;
else
vap->iv_stats.is_scan_passive++;
if (flags & IEEE80211_SCAN_FLUSH)
ss->ss_ops->scan_flush(ss);
/* NB: flush frames rx'd before 1st channel change */
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
ss->ss_ops->scan_start(ss, vap);
if (scan_restart(SCAN_PRIVATE(ss), duration))
ic->ic_flags |= IEEE80211_F_SCAN;
}
} else {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan already in progress\n", __func__,
ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
/* If the running scanning has the flag SCAN_NOPICK set, but
* the requested scan has not, then we update the running scan
* flag. This is needed when wpa_supplicant is used with
* ap_scan=1. Without it, the driver will never associate. */
if (((flags & IEEE80211_SCAN_NOPICK) == 0) &&
(ss->ss_flags & IEEE80211_SCAN_NOPICK)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: clearing SCAN_NOPICK flag\n",
__func__);
ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
}
}
scanning = (ic->ic_flags & IEEE80211_F_SCAN);
IEEE80211_UNLOCK_IRQ(ic);
return scanning;
}
EXPORT_SYMBOL(ieee80211_start_scan);
/*
* Check the scan cache for an ap/channel to use; if that
* fails then kick off a new scan.
*/
int
ieee80211_check_scan(struct ieee80211vap *vap, int flags, u_int duration,
u_int nssid, const struct ieee80211_scan_ssid ssids[],
int (*action)(struct ieee80211vap *, const struct ieee80211_scan_entry *))
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
int checkscanlist = 0;
/*
* Check if there's a list of scan candidates already.
* XXX want more than the ap we're currently associated with
*/
IEEE80211_LOCK_IRQ(ic);
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan, duration %lu, desired mode %s, %s%s%s%s\n",
__func__,
flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
duration,
ieee80211_phymode_name[vap->iv_des_mode],
flags & IEEE80211_SCAN_FLUSH ? "flush" : "append",
flags & IEEE80211_SCAN_NOPICK ? ", nopick" : "",
flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : "",
flags & IEEE80211_SCAN_ONCE ? ", once" : "",
flags & IEEE80211_SCAN_USECACHE ? ", usecache" : "");
if (ss->ss_ops != NULL) {
/* XXX verify ss_ops matches vap->iv_opmode */
if ((flags & IEEE80211_SCAN_NOSSID) == 0) {
/*
* Update the ssid list and mark flags so if
* we call start_scan it doesn't duplicate work.
*/
copy_ssid(vap, ss, nssid, ssids);
flags |= IEEE80211_SCAN_NOSSID;
}
if ((ic->ic_flags & IEEE80211_F_SCAN) == 0 &&
time_before(jiffies, ic->ic_lastscan + vap->iv_scanvalid)) {
/*
* We're not currently scanning and the cache is
* deemed hot enough to consult. Lock out others
* by marking IEEE80211_F_SCAN while we decide if
* something is already in the scan cache we can
* use. Also discard any frames that might come
* in while temporarily marked as scanning.
*/
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
ic->ic_flags |= IEEE80211_F_SCAN;
checkscanlist = 1;
}
}
IEEE80211_UNLOCK_IRQ(ic);
if (checkscanlist) {
/*
* ss must be filled out so scan may be restarted "outside"
* of the current callstack.
*/
ss->ss_flags = flags;
ss->ss_duration = duration;
if (ss->ss_ops->scan_end(ss, ss->ss_vap, action, flags & IEEE80211_SCAN_KEEPMODE)) {
/* found an ap, just clear the flag */
ic->ic_flags &= ~IEEE80211_F_SCAN;
return 1;
}
/* no ap, clear the flag before starting a scan */
ic->ic_flags &= ~IEEE80211_F_SCAN;
}
if ((flags & IEEE80211_SCAN_USECACHE) == 0)
return ieee80211_start_scan(vap, flags, duration, nssid, ssids);
else {
/* If we *must* use the cache and no ap was found, return failure */
return 0;
}
}
/*
* Restart a previous scan. If the previous scan completed
* then we start again using the existing channel list.
*/
int
ieee80211_bg_scan(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
int scanning;
IEEE80211_LOCK_IRQ(ic);
if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
u_int duration;
/*
* Go off-channel for a fixed interval that is large
* enough to catch most APs but short enough that
* we can return on-channel before our listen interval
* expires.
*/
duration = IEEE80211_SCAN_OFFCHANNEL;
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan, jiffies %lu duration %lu\n", __func__,
ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
jiffies, duration);
if (ss->ss_ops != NULL) {
ss->ss_vap = vap;
/*
* A background scan does not select a new STA; it
* just refreshes the scan cache. Also, indicate
* the scan logic should follow the beacon schedule:
* we go off-channel and scan for a while, then
* return to the bss channel to receive a beacon,
* then go off-channel again. All during this time
* we notify the ap we're in power save mode. When
* the scan is complete, we leave power save mode.
* If any beacon indicates there are frames pending
* for us then we drop out of power save mode
* (and background scan) automatically by way of the
* usual STA power save logic.
*/
ss->ss_flags |= IEEE80211_SCAN_NOPICK |
IEEE80211_SCAN_BGSCAN;
/* If previous scan completed, restart */
if (ss->ss_next >= ss->ss_last) {
ss->ss_next = 0;
if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
vap->iv_stats.is_scan_active++;
else
vap->iv_stats.is_scan_passive++;
ss->ss_ops->scan_restart(ss, vap);
}
/* NB: Flush frames RX'd before 1st channel change */
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
ss->ss_mindwell = duration;
if (scan_restart(SCAN_PRIVATE(ss), duration)) {
ic->ic_flags |= IEEE80211_F_SCAN;
ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
}
} else {
/* XXX msg+stat */
}
} else {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan already in progress\n", __func__,
ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
}
scanning = (ic->ic_flags & IEEE80211_F_SCAN);
IEEE80211_UNLOCK_IRQ(ic);
return scanning;
}
EXPORT_SYMBOL(ieee80211_bg_scan);
EXPORT_SYMBOL(ieee80211_cancel_scan);
/*
* Cancel any scan currently going on.
*/
void
ieee80211_cancel_scan(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
IEEE80211_LOCK_IRQ(ic);
if (ic->ic_flags & IEEE80211_F_SCAN) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: cancel %s scan\n", __func__,
ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
/* clear bg scan NOPICK and mark cancel request */
ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_CANCEL;
ss->ss_ops->scan_cancel(ss, vap);
/* force it to fire asap */
mod_timer(&SCAN_PRIVATE(ss)->ss_scan_timer, jiffies);
}
IEEE80211_UNLOCK_IRQ(ic);
}
/*
* Switch to the next channel marked for scanning.
*/
static void
scan_next(unsigned long arg)
{
#define ISCAN_REP (ISCAN_MINDWELL | ISCAN_START | ISCAN_DISCARD)
struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *)arg;
struct ieee80211vap *vap = ss->ss_vap;
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_channel *chan;
unsigned long maxdwell, scanend;
int scanning, scandone, i;
IEEE80211_LOCK_IRQ(ic);
scanning = (ic->ic_flags & IEEE80211_F_SCAN) != 0;
IEEE80211_UNLOCK_IRQ(ic);
if (!scanning) /* canceled */
return;
again:
scandone = (ss->ss_next >= ss->ss_last) ||
((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0);
scanend = SCAN_PRIVATE(ss)->ss_scanend;
if (!scandone &&
(ss->ss_flags & IEEE80211_SCAN_GOTPICK) == 0 &&
((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_START) ||
time_before(jiffies + ss->ss_mindwell, scanend))) {
chan = ss->ss_chans[ss->ss_next++];
/*
* Watch for truncation due to the scan end time.
*/
if (time_after(jiffies + ss->ss_maxdwell, scanend))
maxdwell = scanend - jiffies;
else
maxdwell = ss->ss_maxdwell;
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: chan %3d%c -> %3d%c [%s, dwell min %lu max %lu]\n",
__func__,
ieee80211_chan2ieee(ic, ic->ic_curchan),
channel_type(ic->ic_curchan),
ieee80211_chan2ieee(ic, chan), channel_type(chan),
(ss->ss_flags & IEEE80211_SCAN_ACTIVE) &&
(!IEEE80211_IS_CHAN_PASSIVE(chan)) ?
"active" : "passive",
ss->ss_mindwell, maxdwell);
/*
* Potentially change channel and phy mode.
*/
change_channel(ic, chan);
/*
* If doing an active scan and the channel is not
* marked passive-only then send a probe request.
* Otherwise just listen for traffic on the channel.
*/
if ((ss->ss_flags & IEEE80211_SCAN_ACTIVE) &&
!IEEE80211_IS_CHAN_PASSIVE(chan)) {
struct net_device *dev = vap->iv_dev;
/*
* Send a broadcast probe request followed by
* any specified directed probe requests.
* XXX suppress broadcast probe req?
* XXX remove dependence on vap/vap->iv_bss
* XXX move to policy code?
*/
ieee80211_send_probereq(vap->iv_bss,
vap->iv_myaddr, dev->broadcast,
dev->broadcast,
"", 0,
vap->iv_opt_ie, vap->iv_opt_ie_len);
for (i = 0; i < ss->ss_nssid; i++)
ieee80211_send_probereq(vap->iv_bss,
vap->iv_myaddr, dev->broadcast,
dev->broadcast,
ss->ss_ssid[i].ssid,
ss->ss_ssid[i].len,
vap->iv_opt_ie, vap->iv_opt_ie_len);
}
SCAN_PRIVATE(ss)->ss_chanmindwell = jiffies + ss->ss_mindwell;
mod_timer(&SCAN_PRIVATE(ss)->ss_scan_timer, jiffies + maxdwell);
/* clear mindwell lock and initial channel change flush */
SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
} else {
ic->ic_scan_end(ic); /* notify driver */
/*
* Record scan complete time. Note that we also do
* this when canceled so any background scan will
* not be restarted for a while.
*/
if (scandone)
ic->ic_lastscan = jiffies;
/* return to the bss channel */
if ((ic->ic_bsschan != IEEE80211_CHAN_ANYC) &&
(ic->ic_curchan != ic->ic_bsschan))
change_channel(ic, ic->ic_bsschan);
/* clear internal flags and any indication of a pick */
SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
ss->ss_flags &= ~IEEE80211_SCAN_GOTPICK;
/*
* If not canceled and scan completed, do post-processing.
* If the callback function returns 0, then it wants to
* continue/restart scanning. Unfortunately we needed to
* notify the driver to end the scan above to avoid having
* rx frames alter the scan candidate list.
*/
if (((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) &&
!ss->ss_ops->scan_end(ss, vap, NULL, 0) &&
((ss->ss_flags & IEEE80211_SCAN_ONCE) == 0) &&
time_before(jiffies + ss->ss_mindwell, scanend)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: done, restart "
"[jiffies %lu, dwell min %lu scanend %lu]\n",
__func__,
jiffies, ss->ss_mindwell, scanend);
ss->ss_next = 0; /* reset to beginning */
if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
vap->iv_stats.is_scan_active++;
else
vap->iv_stats.is_scan_passive++;
ic->ic_scan_start(ic); /* notify driver */
goto again;
} else {
if ((ss->ss_flags & IEEE80211_SCAN_BGSCAN) == 0)
scandone = 1;
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s, "
"[jiffies %lu, dwell min %lu scanend %lu]\n",
__func__, scandone ? "done" : "stopped",
jiffies, ss->ss_mindwell, scanend);
/*
* Clear the SCAN bit first in case frames are
* pending on the station power save queue. If
* we defer this then the dispatch of the frames
* may generate a request to cancel scanning.
*/
ic->ic_flags &= ~IEEE80211_F_SCAN;
/*
* Drop out of power save mode when a scan has
* completed. If this scan was prematurely terminated
* because it is a background scan then don't notify
* the ap; we'll either return to scanning after we
* receive the beacon frame or we'll drop out of power
* save mode because the beacon indicates we have frames
* waiting for us.
*/
if (scandone) {
ieee80211_sta_pwrsave(vap, 0);
if (ss->ss_next >= ss->ss_last) {
ieee80211_notify_scan_done(vap);
ic->ic_flags_ext &= ~IEEE80211_FEXT_BGSCAN;
}
}
SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_CANCEL;
ss->ss_flags &=
~(IEEE80211_SCAN_ONCE | IEEE80211_SCAN_PICK1ST);
}
}
#undef ISCAN_REP
}
#ifdef IEEE80211_DEBUG
static void
dump_probe_beacon(u_int8_t subtype, int isnew,
const u_int8_t mac[IEEE80211_ADDR_LEN],
const struct ieee80211_scanparams *sp)
{
printk("[" MAC_FMT "] %s%s on chan %u (bss chan %u) ",
MAC_ADDR(mac), isnew ? "new " : "",
ieee80211_mgt_subtype_name[subtype >> IEEE80211_FC0_SUBTYPE_SHIFT],
sp->chan, sp->bchan);
ieee80211_print_essid(sp->ssid + 2, sp->ssid[1]);
printk("\n");
if (isnew) {
printk("[" MAC_FMT "] caps 0x%x bintval %u erp 0x%x",
MAC_ADDR(mac), sp->capinfo, sp->bintval, sp->erp);
if (sp->country != NULL) {
#ifdef __FreeBSD__
printk(" country info %*D",
sp->country[1], sp->country + 2, " ");
#else
int i;
printk(" country info");
for (i = 0; i < sp->country[1]; i++)
printk(" %02x", sp->country[i + 2]);
#endif
}
printk("\n");
}
}
#endif /* IEEE80211_DEBUG */
/*
* Process a beacon or probe response frame.
*/
void
ieee80211_add_scan(struct ieee80211vap *vap,
const struct ieee80211_scanparams *sp,
const struct ieee80211_frame *wh,
int subtype, int rssi, u_int64_t rtsf)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
/*
* Frames received during startup are discarded to avoid
* using scan state setup on the initial entry to the timer
* callback. This can occur because the device may enable
* rx prior to our doing the initial channel change in the
* timer routine (we defer the channel change to the timer
* code to simplify locking on linux).
*/
if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_DISCARD)
return;
#ifdef IEEE80211_DEBUG
if (ieee80211_msg_scan(vap) && (ic->ic_flags & IEEE80211_F_SCAN))
dump_probe_beacon(subtype, 1, wh->i_addr2, sp);
#endif
if (ss->ss_ops != NULL &&
ss->ss_ops->scan_add(ss, sp, wh, subtype, rssi, rtsf)) {
/*
* If we've reached the min dwell time terminate
* the timer so we'll switch to the next channel.
*/
if ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_MINDWELL) == 0 &&
time_after_eq(jiffies, SCAN_PRIVATE(ss)->ss_chanmindwell)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: chan %3d%c min dwell met (%lu > %lu)\n",
__func__,
ieee80211_chan2ieee(ic, ic->ic_curchan),
channel_type(ic->ic_curchan),
jiffies, SCAN_PRIVATE(ss)->ss_chanmindwell);
/*
* XXX
* We want to just kick the timer and still
* process frames until it fires but linux
* will livelock unless we discard frames.
*/
#if 0
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_MINDWELL;
#else
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
#endif
/* NB: trigger at next clock tick */
mod_timer(&SCAN_PRIVATE(ss)->ss_scan_timer, jiffies);
}
}
}
/*
* Timeout/age scan cache entries; called from sta timeout
* timer (XXX should be self-contained).
*/
void
ieee80211_scan_timeout(struct ieee80211com *ic)
{
struct ieee80211_scan_state *ss = ic->ic_scan;
if (ss->ss_ops != NULL)
ss->ss_ops->scan_age(ss);
}
/*
* Mark a scan cache entry after a successful associate.
*/
void
ieee80211_scan_assoc_success(struct ieee80211com *ic, const u_int8_t mac[])
{
struct ieee80211_scan_state *ss = ic->ic_scan;
if (ss->ss_ops != NULL) {
IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
mac, "%s", __func__);
ss->ss_ops->scan_assoc_success(ss, mac);
}
}
/*
* Demerit a scan cache entry after failing to associate.
*/
void
ieee80211_scan_assoc_fail(struct ieee80211com *ic,
const u_int8_t mac[], int reason)
{
struct ieee80211_scan_state *ss = ic->ic_scan;
if (ss->ss_ops != NULL) {
IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN, mac,
"%s: reason %u", __func__, reason);
ss->ss_ops->scan_assoc_fail(ss, mac, reason);
}
}
/*
* Iterate over the contents of the scan cache.
*/
int
ieee80211_scan_iterate(struct ieee80211com *ic,
ieee80211_scan_iter_func *f, void *arg)
{
int res = 0;
struct ieee80211_scan_state *ss = ic->ic_scan;
if (ss->ss_ops != NULL) {
res = ss->ss_ops->scan_iterate(ss, f, arg);
}
return res;
}
/*
* Flush the contents of the scan cache.
*/
void
ieee80211_scan_flush(struct ieee80211com *ic)
{
struct ieee80211_scan_state *ss = ic->ic_scan;
if (ss->ss_ops != NULL) {
IEEE80211_DPRINTF(ss->ss_vap, IEEE80211_MSG_SCAN,
"%s\n", __func__);
ss->ss_ops->scan_flush(ss);
}
}
/* Check if a channel is usable for a DFS channel switch */
static int
ieee80211_dfs_is_channel_usable(struct ieee80211com *ic,
struct ieee80211_channel *channel)
{
u_int16_t curChanBandFlags, curChanOutdoorFlags;
/*
* Criteria for the new frequency:
* - it must be different from the current frequency
* - it must not have radar detected
* - it must be an active channel
* - it must be in the same band (2.4Ghz/5Ghz)
* - it must be suitable for indoor/outdoor use according to what the
* user selected
*/
curChanBandFlags = ic->ic_bsschan->ic_flags &
(IEEE80211_CHAN_2GHZ | IEEE80211_CHAN_5GHZ);
curChanOutdoorFlags = ic->ic_country_outdoor ?
IEEE80211_CHAN_OUTDOOR : IEEE80211_CHAN_INDOOR;
return ((channel->ic_freq != ic->ic_bsschan->ic_freq) &&
(!IEEE80211_IS_CHAN_RADAR(channel) &&
(ic->ic_flags & IEEE80211_F_DOTH)) &&
(isset(ic->ic_chan_active, channel->ic_ieee)) &&
(channel->ic_flags & curChanBandFlags) &&
(channel->ic_flags & curChanOutdoorFlags));
}
/*
* Execute radar channel change. This is called when a radar signal is
* detected. AP/IBSS mode only. Return 1 on success, 0 on failure
*/
void
ieee80211_scan_dfs_action(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_channel *new_channel = NULL;
int chanStart, i, count;
if (!IEEE80211_IS_MODE_DFS_MASTER(vap->iv_opmode)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: called but not in DFS master mode\n",
__func__);
return;
}
/* Do nothing if a channel switch is already in progress */
if (ic->ic_flags & IEEE80211_F_CHANSWITCH) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: channel switch already in progress\n",
__func__);
return;
}
if ((ic->ic_curchan != NULL) &&
(ic->ic_curchan != IEEE80211_CHAN_ANYC)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: ic_curchan is %3d (%4d MHz)\n",
__func__, ic->ic_curchan->ic_ieee,
ic->ic_curchan->ic_freq);
}
if ((ic->ic_bsschan != NULL) &&
(ic->ic_bsschan != IEEE80211_CHAN_ANYC)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: ic_bsschan is %3d (%4d MHz)\n",
__func__, ic->ic_bsschan->ic_ieee,
ic->ic_bsschan->ic_freq);
}
/* According to FCC/ETSI rules on uniform spreading, we shall select a
* channel out of the list of usable channels so that the probability
* of selecting a given channel shall be the same for all channels
* (reference: ETSI 301 893 v1.3.1 $4.6.2.5.1 */
/* First, we count the usable channels */
count = 0;
for (i = 0; i < ic->ic_nchans; i++) {
if (ieee80211_dfs_is_channel_usable(
ic, &ic->ic_channels[i])) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: usable channel %3d "
"(%4d MHz)\n",
__func__,
ic->ic_channels[i].ic_ieee,
ic->ic_channels[i].ic_freq);
count ++;
}
}
if (count != 0) {
/* Next, we pickup a random usable channel */
chanStart = jiffies % count;
count = 0;
for (i = 0; i < ic->ic_nchans; i++) {
/* must be the same formula as above */
if (ieee80211_dfs_is_channel_usable(
ic, &ic->ic_channels[i])) {
if (count++ == chanStart) {
new_channel =
&ic->ic_channels[i];
break;
}
}
}
}
if (new_channel == NULL) {
/* We found no channel to switch to (for instance, all
* available channels are under Non-Occupancy Period). In this
* case, we still need to send an action frame and beacon with
* CSA IE to tell other nodes to stop their transmission, in
* order to meet the Channel Closing Transmission Time
* requirement of FCC/ETSI */
if ((ic->ic_bsschan != NULL) &&
(ic->ic_bsschan != IEEE80211_CHAN_ANYC)) {
new_channel = ic->ic_bsschan;
}
}
if (new_channel != NULL) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: new channel found %3d "
"(%4d MHz)\n", __func__,
new_channel->ic_ieee,
new_channel->ic_freq);
/* send a CSA frame immediately */
ieee80211_send_csa_frame(vap,
IEEE80211_CSA_MUST_STOP_TX,
new_channel->ic_ieee,
IEEE80211_RADAR_CHANCHANGE_TBTT_COUNT);
/* A suitable scan entry was found, so change channels */
if (vap->iv_state == IEEE80211_S_RUN) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: CSA switching to channel %3d (%4d MHz)\n",
__func__,
new_channel->ic_ieee,
new_channel->ic_freq);
ieee80211_start_new_csa(vap,
IEEE80211_CSA_MUST_STOP_TX, new_channel,
IEEE80211_RADAR_CHANCHANGE_TBTT_COUNT, 0);
} else {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: directly switching to channel "
"%3d (%4d MHz)\n", __func__,
new_channel->ic_ieee,
new_channel->ic_freq);
/* VAP is not in run state yet. so
* change the channel here. */
change_channel(ic, new_channel);
ic->ic_bsschan = new_channel;
if (vap->iv_bss)
vap->iv_bss->ni_chan = new_channel;
}
} else {
/* A suitable scan entry was not found */
IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
"%s: new channel not found\n", __func__);
}
}
EXPORT_SYMBOL(ieee80211_scan_dfs_action);
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