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freebsd-dev/sys/net80211/ieee80211_scan.c
Adrian Chadd 66b74386c7 Attempt to catch scan cancellations at exactly the wrong time from occuring. 
The scan code unlocks the comlock and calls into the driver.  It then
assumes the state hasn't changed from underneath it.

Although I haven't seen this particular condition trigger, I'd like to
be informed if I or anyone else sees it.

What I'm thinking may occur:

* A cancellation comes in during the scan_end call;
* the cancel flag is set;
* but it's never checked, so scandone isn't updated;
* .. and the interface stays in the STA power save mode.

It's a subtle race, if it even exists.

PR:		kern/163318
2012-03-02 02:53:43 +00:00

1255 lines
36 KiB
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/*-
* Copyright (c) 2002-2008 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.
*
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* IEEE 802.11 scanning support.
*/
#include "opt_wlan.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/condvar.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_media.h>
#include <net/ethernet.h>
#include <net80211/ieee80211_var.h>
#include <net/bpf.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_ABORT 0x0008 /* end the scan immediately */
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 task ss_scan_task; /* scan execution */
struct cv ss_scan_cv; /* scan signal */
struct callout 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
* ap's 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_ticks(150)
/*
* Roaming-related defaults. RSSI thresholds are as returned by the
* driver (.5dBm). Transmit rate thresholds are IEEE rate codes (i.e
* .5M units) or MCS.
*/
/* rssi thresholds */
#define ROAM_RSSI_11A_DEFAULT 14 /* 11a bss */
#define ROAM_RSSI_11B_DEFAULT 14 /* 11b bss */
#define ROAM_RSSI_11BONLY_DEFAULT 14 /* 11b-only bss */
/* transmit rate thresholds */
#define ROAM_RATE_11A_DEFAULT 2*12 /* 11a bss */
#define ROAM_RATE_11B_DEFAULT 2*5 /* 11b bss */
#define ROAM_RATE_11BONLY_DEFAULT 2*1 /* 11b-only bss */
#define ROAM_RATE_HALF_DEFAULT 2*6 /* half-width 11a/g bss */
#define ROAM_RATE_QUARTER_DEFAULT 2*3 /* quarter-width 11a/g bss */
#define ROAM_MCS_11N_DEFAULT (1 | IEEE80211_RATE_MCS) /* 11n bss */
static void scan_curchan(struct ieee80211_scan_state *, unsigned long);
static void scan_mindwell(struct ieee80211_scan_state *);
static void scan_signal(void *);
static void scan_task(void *, int);
MALLOC_DEFINE(M_80211_SCAN, "80211scan", "802.11 scan state");
void
ieee80211_scan_attach(struct ieee80211com *ic)
{
struct scan_state *ss;
ss = (struct scan_state *) malloc(sizeof(struct scan_state),
M_80211_SCAN, M_NOWAIT | M_ZERO);
if (ss == NULL) {
ic->ic_scan = NULL;
return;
}
callout_init_mtx(&ss->ss_scan_timer, IEEE80211_LOCK_OBJ(ic), 0);
cv_init(&ss->ss_scan_cv, "scan");
TASK_INIT(&ss->ss_scan_task, 0, scan_task, ss);
ic->ic_scan = &ss->base;
ss->base.ss_ic = ic;
ic->ic_scan_curchan = scan_curchan;
ic->ic_scan_mindwell = scan_mindwell;
}
void
ieee80211_scan_detach(struct ieee80211com *ic)
{
struct ieee80211_scan_state *ss = ic->ic_scan;
if (ss != NULL) {
IEEE80211_LOCK(ic);
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_ABORT;
scan_signal(ss);
IEEE80211_UNLOCK(ic);
ieee80211_draintask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
callout_drain(&SCAN_PRIVATE(ss)->ss_scan_timer);
KASSERT((ic->ic_flags & IEEE80211_F_SCAN) == 0,
("scan still running"));
if (ss->ss_ops != NULL) {
ss->ss_ops->scan_detach(ss);
ss->ss_ops = NULL;
}
ic->ic_scan = NULL;
free(SCAN_PRIVATE(ss), M_80211_SCAN);
}
}
static const struct ieee80211_roamparam defroam[IEEE80211_MODE_MAX] = {
[IEEE80211_MODE_11A] = { .rssi = ROAM_RSSI_11A_DEFAULT,
.rate = ROAM_RATE_11A_DEFAULT },
[IEEE80211_MODE_11G] = { .rssi = ROAM_RSSI_11B_DEFAULT,
.rate = ROAM_RATE_11B_DEFAULT },
[IEEE80211_MODE_11B] = { .rssi = ROAM_RSSI_11BONLY_DEFAULT,
.rate = ROAM_RATE_11BONLY_DEFAULT },
[IEEE80211_MODE_TURBO_A]= { .rssi = ROAM_RSSI_11A_DEFAULT,
.rate = ROAM_RATE_11A_DEFAULT },
[IEEE80211_MODE_TURBO_G]= { .rssi = ROAM_RSSI_11A_DEFAULT,
.rate = ROAM_RATE_11A_DEFAULT },
[IEEE80211_MODE_STURBO_A]={ .rssi = ROAM_RSSI_11A_DEFAULT,
.rate = ROAM_RATE_11A_DEFAULT },
[IEEE80211_MODE_HALF] = { .rssi = ROAM_RSSI_11A_DEFAULT,
.rate = ROAM_RATE_HALF_DEFAULT },
[IEEE80211_MODE_QUARTER]= { .rssi = ROAM_RSSI_11A_DEFAULT,
.rate = ROAM_RATE_QUARTER_DEFAULT },
[IEEE80211_MODE_11NA] = { .rssi = ROAM_RSSI_11A_DEFAULT,
.rate = ROAM_MCS_11N_DEFAULT },
[IEEE80211_MODE_11NG] = { .rssi = ROAM_RSSI_11B_DEFAULT,
.rate = ROAM_MCS_11N_DEFAULT },
};
void
ieee80211_scan_vattach(struct ieee80211vap *vap)
{
vap->iv_bgscanidle = (IEEE80211_BGSCAN_IDLE_DEFAULT*1000)/hz;
vap->iv_bgscanintvl = IEEE80211_BGSCAN_INTVAL_DEFAULT*hz;
vap->iv_scanvalid = IEEE80211_SCAN_VALID_DEFAULT*hz;
vap->iv_roaming = IEEE80211_ROAMING_AUTO;
memcpy(vap->iv_roamparms, defroam, sizeof(defroam));
}
void
ieee80211_scan_vdetach(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss;
IEEE80211_LOCK(ic);
ss = ic->ic_scan;
if (ss != NULL && ss->ss_vap == vap) {
if (ic->ic_flags & IEEE80211_F_SCAN) {
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_ABORT;
scan_signal(ss);
}
if (ss->ss_ops != NULL) {
ss->ss_ops->scan_detach(ss);
ss->ss_ops = NULL;
}
ss->ss_vap = NULL;
}
IEEE80211_UNLOCK(ic);
}
/*
* Simple-minded scanner module support.
*/
static const char *scan_modnames[IEEE80211_OPMODE_MAX] = {
"wlan_scan_sta", /* IEEE80211_M_IBSS */
"wlan_scan_sta", /* IEEE80211_M_STA */
"wlan_scan_wds", /* IEEE80211_M_WDS */
"wlan_scan_sta", /* IEEE80211_M_AHDEMO */
"wlan_scan_ap", /* IEEE80211_M_HOSTAP */
"wlan_scan_monitor", /* IEEE80211_M_MONITOR */
"wlan_scan_sta", /* IEEE80211_M_MBSS */
};
static const struct ieee80211_scanner *scanners[IEEE80211_OPMODE_MAX];
const struct ieee80211_scanner *
ieee80211_scanner_get(enum ieee80211_opmode mode)
{
if (mode >= IEEE80211_OPMODE_MAX)
return NULL;
if (scanners[mode] == NULL)
ieee80211_load_module(scan_modnames[mode]);
return scanners[mode];
}
void
ieee80211_scanner_register(enum ieee80211_opmode mode,
const struct ieee80211_scanner *scan)
{
if (mode >= IEEE80211_OPMODE_MAX)
return;
scanners[mode] = scan;
}
void
ieee80211_scanner_unregister(enum ieee80211_opmode mode,
const struct ieee80211_scanner *scan)
{
if (mode >= IEEE80211_OPMODE_MAX)
return;
if (scanners[mode] == scan)
scanners[mode] = NULL;
}
void
ieee80211_scanner_unregister_all(const struct ieee80211_scanner *scan)
{
int m;
for (m = 0; m < IEEE80211_OPMODE_MAX; m++)
if (scanners[m] == scan)
scanners[m] = NULL;
}
/*
* Update common scanner state to reflect the current
* operating mode. This is called when the state machine
* is transitioned to RUN state w/o scanning--e.g. when
* operating in monitor mode. The purpose of this is to
* ensure later callbacks find ss_ops set to properly
* reflect current operating mode.
*/
static void
scan_update_locked(struct ieee80211vap *vap,
const struct ieee80211_scanner *scan)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
IEEE80211_LOCK_ASSERT(ic);
#ifdef IEEE80211_DEBUG
if (ss->ss_vap != vap || ss->ss_ops != scan) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: current scanner is <%s:%s>, switch to <%s:%s>\n",
__func__,
ss->ss_vap != NULL ?
ss->ss_vap->iv_ifp->if_xname : "none",
ss->ss_vap != NULL ?
ieee80211_opmode_name[ss->ss_vap->iv_opmode] : "none",
vap->iv_ifp->if_xname,
ieee80211_opmode_name[vap->iv_opmode]);
}
#endif
ss->ss_vap = vap;
if (ss->ss_ops != scan) {
/*
* Switch scanners; detach old, attach new. Special
* case where a single scan module implements multiple
* policies by using different scan ops but a common
* core. We assume if the old and new attach methods
* are identical then it's ok to just change ss_ops
* and not flush the internal state of the module.
*/
if (scan == NULL || ss->ss_ops == NULL ||
ss->ss_ops->scan_attach != scan->scan_attach) {
if (ss->ss_ops != NULL)
ss->ss_ops->scan_detach(ss);
if (scan != NULL && !scan->scan_attach(ss)) {
/* XXX attach failure */
/* XXX stat+msg */
scan = NULL;
}
}
ss->ss_ops = scan;
}
}
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_HT(c))
return 'n';
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_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];
printf("%s%u%c", sep, ieee80211_chan2ieee(ic, c),
channel_type(c));
sep = ", ";
}
}
#ifdef IEEE80211_DEBUG
static void
scan_dump(struct ieee80211_scan_state *ss)
{
struct ieee80211vap *vap = ss->ss_vap;
if_printf(vap->iv_ifp, "scan set ");
ieee80211_scan_dump_channels(ss);
printf(" dwell min %lums max %lums\n",
ticks_to_msecs(ss->ss_mindwell), ticks_to_msecs(ss->ss_maxdwell));
}
#endif /* IEEE80211_DEBUG */
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 printf */
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.
*/
static int
start_scan_locked(const struct ieee80211_scanner *scan,
struct ieee80211vap *vap, int flags, u_int duration,
u_int mindwell, u_int maxdwell,
u_int nssid, const struct ieee80211_scan_ssid ssids[])
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
IEEE80211_LOCK_ASSERT(ic);
if (ic->ic_flags & IEEE80211_F_CSAPENDING) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: scan inhibited by pending channel change\n", __func__);
} else if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan, duration %u mindwell %u maxdwell %u, desired mode %s, %s%s%s%s%s%s\n"
, __func__
, flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive"
, duration, mindwell, maxdwell
, ieee80211_phymode_name[vap->iv_des_mode]
, flags & IEEE80211_SCAN_FLUSH ? "flush" : "append"
, flags & IEEE80211_SCAN_NOPICK ? ", nopick" : ""
, flags & IEEE80211_SCAN_NOJOIN ? ", nojoin" : ""
, flags & IEEE80211_SCAN_NOBCAST ? ", nobcast" : ""
, flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : ""
, flags & IEEE80211_SCAN_ONCE ? ", once" : ""
);
scan_update_locked(vap, 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);
if (flags & IEEE80211_SCAN_BGSCAN)
ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
/* NB: flush frames rx'd before 1st channel change */
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
SCAN_PRIVATE(ss)->ss_duration = duration;
ss->ss_next = 0;
ss->ss_mindwell = mindwell;
ss->ss_maxdwell = maxdwell;
/* NB: scan_start must be before the scan runtask */
ss->ss_ops->scan_start(ss, vap);
#ifdef IEEE80211_DEBUG
if (ieee80211_msg_scan(vap))
scan_dump(ss);
#endif /* IEEE80211_DEBUG */
ic->ic_flags |= IEEE80211_F_SCAN;
ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
}
return 1;
} else {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan already in progress\n", __func__,
ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
}
return 0;
}
/*
* Start a scan unless one is already going.
*/
int
ieee80211_start_scan(struct ieee80211vap *vap, int flags,
u_int duration, u_int mindwell, u_int maxdwell,
u_int nssid, const struct ieee80211_scan_ssid ssids[])
{
struct ieee80211com *ic = vap->iv_ic;
const struct ieee80211_scanner *scan;
int result;
scan = ieee80211_scanner_get(vap->iv_opmode);
if (scan == NULL) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: no scanner support for %s mode\n",
__func__, ieee80211_opmode_name[vap->iv_opmode]);
/* XXX stat */
return 0;
}
IEEE80211_LOCK(ic);
result = start_scan_locked(scan, vap, flags, duration,
mindwell, maxdwell, nssid, ssids);
IEEE80211_UNLOCK(ic);
return result;
}
/*
* 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 mindwell, u_int maxdwell,
u_int nssid, const struct ieee80211_scan_ssid ssids[])
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
const struct ieee80211_scanner *scan;
int result;
scan = ieee80211_scanner_get(vap->iv_opmode);
if (scan == NULL) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: no scanner support for %s mode\n",
__func__, vap->iv_opmode);
/* XXX stat */
return 0;
}
/*
* Check if there's a list of scan candidates already.
* XXX want more than the ap we're currently associated with
*/
IEEE80211_LOCK(ic);
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s scan, %s%s%s%s%s\n"
, __func__
, flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive"
, flags & IEEE80211_SCAN_FLUSH ? "flush" : "append"
, flags & IEEE80211_SCAN_NOPICK ? ", nopick" : ""
, flags & IEEE80211_SCAN_NOJOIN ? ", nojoin" : ""
, flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : ""
, flags & IEEE80211_SCAN_ONCE ? ", once" : ""
);
if (ss->ss_ops != scan) {
/* XXX re-use cache contents? e.g. adhoc<->sta */
flags |= IEEE80211_SCAN_FLUSH;
}
scan_update_locked(vap, scan);
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 &&
(flags & IEEE80211_SCAN_FLUSH) == 0 &&
time_before(ticks, 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;
/* NB: need to use supplied flags in check */
ss->ss_flags = flags & 0xff;
result = ss->ss_ops->scan_end(ss, vap);
ic->ic_flags &= ~IEEE80211_F_SCAN;
SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_DISCARD;
if (result) {
ieee80211_notify_scan_done(vap);
IEEE80211_UNLOCK(ic);
return 1;
}
}
}
result = start_scan_locked(scan, vap, flags, duration,
mindwell, maxdwell, nssid, ssids);
IEEE80211_UNLOCK(ic);
return result;
}
/*
* Check the scan cache for an ap/channel to use; if that fails
* then kick off a scan using the current settings.
*/
int
ieee80211_check_scan_current(struct ieee80211vap *vap)
{
return ieee80211_check_scan(vap,
IEEE80211_SCAN_ACTIVE,
IEEE80211_SCAN_FOREVER, 0, 0,
vap->iv_des_nssid, vap->iv_des_ssid);
}
/*
* 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, int flags)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
const struct ieee80211_scanner *scan;
scan = ieee80211_scanner_get(vap->iv_opmode);
if (scan == NULL) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: no scanner support for %s mode\n",
__func__, vap->iv_opmode);
/* XXX stat */
return 0;
}
IEEE80211_LOCK(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 ap's 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, ticks %u duration %lu\n", __func__,
ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
ticks, duration);
scan_update_locked(vap, scan);
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
| flags
;
/* if previous scan completed, restart */
if (ss->ss_next >= ss->ss_last) {
if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
vap->iv_stats.is_scan_active++;
else
vap->iv_stats.is_scan_passive++;
/*
* NB: beware of the scan cache being flushed;
* if the channel list is empty use the
* scan_start method to populate it.
*/
ss->ss_next = 0;
if (ss->ss_last != 0)
ss->ss_ops->scan_restart(ss, vap);
else {
ss->ss_ops->scan_start(ss, vap);
#ifdef IEEE80211_DEBUG
if (ieee80211_msg_scan(vap))
scan_dump(ss);
#endif /* IEEE80211_DEBUG */
}
}
/* NB: flush frames rx'd before 1st channel change */
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
SCAN_PRIVATE(ss)->ss_duration = duration;
ss->ss_maxdwell = duration;
ic->ic_flags |= IEEE80211_F_SCAN;
ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
} 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");
}
IEEE80211_UNLOCK(ic);
/* NB: racey, does it matter? */
return (ic->ic_flags & IEEE80211_F_SCAN);
}
/*
* Cancel any scan currently going on for the specified vap.
*/
void
ieee80211_cancel_scan(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
IEEE80211_LOCK(ic);
if ((ic->ic_flags & IEEE80211_F_SCAN) &&
ss->ss_vap == vap &&
(SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) {
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;
/* wake up the scan task */
scan_signal(ss);
}
IEEE80211_UNLOCK(ic);
}
/*
* Cancel any scan currently going on.
*/
void
ieee80211_cancel_anyscan(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
IEEE80211_LOCK(ic);
if ((ic->ic_flags & IEEE80211_F_SCAN) &&
(SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) {
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;
/* wake up the scan task */
scan_signal(ss);
}
IEEE80211_UNLOCK(ic);
}
/*
* Public access to scan_next for drivers that manage
* scanning themselves (e.g. for firmware-based devices).
*/
void
ieee80211_scan_next(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
/* wake up the scan task */
IEEE80211_LOCK(ic);
scan_signal(ss);
IEEE80211_UNLOCK(ic);
}
/*
* Public access to scan_next for drivers that are not able to scan single
* channels (e.g. for firmware-based devices).
*/
void
ieee80211_scan_done(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss;
IEEE80211_LOCK(ic);
ss = ic->ic_scan;
ss->ss_next = ss->ss_last; /* all channels are complete */
scan_signal(ss);
IEEE80211_UNLOCK(ic);
}
/*
* Probe the curent channel, if allowed, while scanning.
* If the channel is not marked passive-only then send
* a probe request immediately. Otherwise mark state and
* listen for beacons on the channel; if we receive something
* then we'll transmit a probe request.
*/
void
ieee80211_probe_curchan(struct ieee80211vap *vap, int force)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
struct ifnet *ifp = vap->iv_ifp;
int i;
if ((ic->ic_curchan->ic_flags & IEEE80211_CHAN_PASSIVE) && !force) {
ic->ic_flags_ext |= IEEE80211_FEXT_PROBECHAN;
return;
}
/*
* Send directed probe requests followed by any
* broadcast probe request.
* XXX remove dependence on ic/vap->iv_bss
*/
for (i = 0; i < ss->ss_nssid; i++)
ieee80211_send_probereq(vap->iv_bss,
vap->iv_myaddr, ifp->if_broadcastaddr,
ifp->if_broadcastaddr,
ss->ss_ssid[i].ssid, ss->ss_ssid[i].len);
if ((ss->ss_flags & IEEE80211_SCAN_NOBCAST) == 0)
ieee80211_send_probereq(vap->iv_bss,
vap->iv_myaddr, ifp->if_broadcastaddr,
ifp->if_broadcastaddr,
"", 0);
}
/*
* Scan curchan. If this is an active scan and the channel
* is not marked passive then send probe request frame(s).
* Arrange for the channel change after maxdwell ticks.
*/
static void
scan_curchan(struct ieee80211_scan_state *ss, unsigned long maxdwell)
{
struct ieee80211vap *vap = ss->ss_vap;
IEEE80211_LOCK(vap->iv_ic);
if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
ieee80211_probe_curchan(vap, 0);
callout_reset(&SCAN_PRIVATE(ss)->ss_scan_timer,
maxdwell, scan_signal, ss);
IEEE80211_UNLOCK(vap->iv_ic);
}
static void
scan_signal(void *arg)
{
struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *) arg;
IEEE80211_LOCK_ASSERT(ss->ss_ic);
cv_signal(&SCAN_PRIVATE(ss)->ss_scan_cv);
}
/*
* Handle mindwell requirements completed; initiate a channel
* change to the next channel asap.
*/
static void
scan_mindwell(struct ieee80211_scan_state *ss)
{
struct ieee80211com *ic = ss->ss_ic;
IEEE80211_LOCK(ic);
scan_signal(ss);
IEEE80211_UNLOCK(ic);
}
static void
scan_task(void *arg, int pending)
{
#define ISCAN_REP (ISCAN_MINDWELL | ISCAN_DISCARD)
struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *) arg;
struct ieee80211vap *vap = ss->ss_vap;
struct ieee80211com *ic = ss->ss_ic;
struct ieee80211_channel *chan;
unsigned long maxdwell, scanend;
int scandone = 0;
IEEE80211_LOCK(ic);
if (vap == NULL || (ic->ic_flags & IEEE80211_F_SCAN) == 0 ||
(SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)) {
/* Cancelled before we started */
goto done;
}
if (ss->ss_next == ss->ss_last) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: no channels to scan\n", __func__);
goto done;
}
if (vap->iv_opmode == IEEE80211_M_STA &&
vap->iv_state == IEEE80211_S_RUN) {
if ((vap->iv_bss->ni_flags & IEEE80211_NODE_PWR_MGT) == 0) {
/* Enable station power save mode */
ieee80211_sta_pwrsave(vap, 1);
/*
* Use an 1ms delay so the null data frame has a chance
* to go out.
* XXX Should use M_TXCB mechanism to eliminate this.
*/
cv_timedwait(&SCAN_PRIVATE(ss)->ss_scan_cv,
IEEE80211_LOCK_OBJ(ic), hz / 1000);
if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)
goto done;
}
}
scanend = ticks + SCAN_PRIVATE(ss)->ss_duration;
IEEE80211_UNLOCK(ic);
ic->ic_scan_start(ic); /* notify driver */
IEEE80211_LOCK(ic);
for (;;) {
scandone = (ss->ss_next >= ss->ss_last) ||
(SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0;
if (scandone || (ss->ss_flags & IEEE80211_SCAN_GOTPICK) ||
(SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT) ||
time_after(ticks + ss->ss_mindwell, scanend))
break;
chan = ss->ss_chans[ss->ss_next++];
/*
* Watch for truncation due to the scan end time.
*/
if (time_after(ticks + ss->ss_maxdwell, scanend))
maxdwell = scanend - ticks;
else
maxdwell = ss->ss_maxdwell;
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: chan %3d%c -> %3d%c [%s, dwell min %lums max %lums]\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) &&
(chan->ic_flags & IEEE80211_CHAN_PASSIVE) == 0 ?
"active" : "passive",
ticks_to_msecs(ss->ss_mindwell), ticks_to_msecs(maxdwell));
/*
* Potentially change channel and phy mode.
*/
ic->ic_curchan = chan;
ic->ic_rt = ieee80211_get_ratetable(chan);
IEEE80211_UNLOCK(ic);
/*
* Perform the channel change and scan unlocked so the driver
* may sleep. Once set_channel returns the hardware has
* completed the channel change.
*/
ic->ic_set_channel(ic);
ieee80211_radiotap_chan_change(ic);
/*
* Scan curchan. Drivers for "intelligent hardware"
* override ic_scan_curchan to tell the device to do
* the work. Otherwise we manage the work outselves;
* sending a probe request (as needed), and arming the
* timeout to switch channels after maxdwell ticks.
*
* scan_curchan should only pause for the time required to
* prepare/initiate the hardware for the scan (if at all), the
* below condvar is used to sleep for the channels dwell time
* and allows it to be signalled for abort.
*/
ic->ic_scan_curchan(ss, maxdwell);
IEEE80211_LOCK(ic);
SCAN_PRIVATE(ss)->ss_chanmindwell = ticks + ss->ss_mindwell;
/* clear mindwell lock and initial channel change flush */
SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
if ((SCAN_PRIVATE(ss)->ss_iflags & (ISCAN_CANCEL|ISCAN_ABORT)))
continue;
/* Wait to be signalled to scan the next channel */
cv_wait(&SCAN_PRIVATE(ss)->ss_scan_cv, IEEE80211_LOCK_OBJ(ic));
}
if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)
goto done;
IEEE80211_UNLOCK(ic);
ic->ic_scan_end(ic); /* notify driver */
IEEE80211_LOCK(ic);
/*
* Since a cancellation may have occured during one of the
* driver calls (whilst unlocked), update scandone.
*/
if (scandone == 0 &&
((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0)) {
/* XXX printf? */
if_printf(vap->iv_ifp,
"%s: OOPS! scan cancelled during driver call!\n",
__func__);
}
scandone |= ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0);
/*
* 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 = ticks;
/* return to the bss channel */
if (ic->ic_bsschan != IEEE80211_CHAN_ANYC &&
ic->ic_curchan != ic->ic_bsschan) {
ieee80211_setupcurchan(ic, ic->ic_bsschan);
IEEE80211_UNLOCK(ic);
ic->ic_set_channel(ic);
ieee80211_radiotap_chan_change(ic);
IEEE80211_LOCK(ic);
}
/* 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) &&
(ss->ss_flags & IEEE80211_SCAN_ONCE) == 0 &&
time_before(ticks + ss->ss_mindwell, scanend)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: done, restart "
"[ticks %u, dwell min %lu scanend %lu]\n",
__func__,
ticks, ss->ss_mindwell, scanend);
ss->ss_next = 0; /* reset to begining */
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); /* XXX? */
ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
IEEE80211_UNLOCK(ic);
return;
}
/* past here, scandone is ``true'' if not in bg mode */
if ((ss->ss_flags & IEEE80211_SCAN_BGSCAN) == 0)
scandone = 1;
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: %s, [ticks %u, dwell min %lu scanend %lu]\n",
__func__, scandone ? "done" : "stopped",
ticks, 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.
*/
done:
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|ISCAN_ABORT);
ss->ss_flags &= ~(IEEE80211_SCAN_ONCE | IEEE80211_SCAN_PICK1ST);
IEEE80211_UNLOCK(ic);
#undef ISCAN_REP
}
#ifdef IEEE80211_DEBUG
static void
dump_country(const uint8_t *ie)
{
const struct ieee80211_country_ie *cie =
(const struct ieee80211_country_ie *) ie;
int i, nbands, schan, nchan;
if (cie->len < 3) {
printf(" <bogus country ie, len %d>", cie->len);
return;
}
printf(" country [%c%c%c", cie->cc[0], cie->cc[1], cie->cc[2]);
nbands = (cie->len - 3) / sizeof(cie->band[0]);
for (i = 0; i < nbands; i++) {
schan = cie->band[i].schan;
nchan = cie->band[i].nchan;
if (nchan != 1)
printf(" %u-%u,%u", schan, schan + nchan-1,
cie->band[i].maxtxpwr);
else
printf(" %u,%u", schan, cie->band[i].maxtxpwr);
}
printf("]");
}
static void
dump_probe_beacon(uint8_t subtype, int isnew,
const uint8_t mac[IEEE80211_ADDR_LEN],
const struct ieee80211_scanparams *sp, int rssi)
{
printf("[%s] %s%s on chan %u (bss chan %u) ",
ether_sprintf(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]);
printf(" rssi %d\n", rssi);
if (isnew) {
printf("[%s] caps 0x%x bintval %u erp 0x%x",
ether_sprintf(mac), sp->capinfo, sp->bintval, sp->erp);
if (sp->country != NULL)
dump_country(sp->country);
printf("\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, int noise)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_scan_state *ss = ic->ic_scan;
/* XXX locking */
/*
* 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.
*/
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, rssi);
#endif
if (ss->ss_ops != NULL &&
ss->ss_ops->scan_add(ss, sp, wh, subtype, rssi, noise)) {
/*
* 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(ticks, SCAN_PRIVATE(ss)->ss_chanmindwell)) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: chan %3d%c min dwell met (%u > %lu)\n",
__func__,
ieee80211_chan2ieee(ic, ic->ic_curchan),
channel_type(ic->ic_curchan),
ticks, SCAN_PRIVATE(ss)->ss_chanmindwell);
SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_MINDWELL;
/*
* NB: trigger at next clock tick or wait for the
* hardware.
*/
ic->ic_scan_mindwell(ss);
}
}
}
/*
* 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 ieee80211vap *vap, const uint8_t mac[])
{
struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
if (ss->ss_ops != NULL) {
IEEE80211_NOTE_MAC(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 ieee80211vap *vap,
const uint8_t mac[], int reason)
{
struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
if (ss->ss_ops != NULL) {
IEEE80211_NOTE_MAC(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.
*/
void
ieee80211_scan_iterate(struct ieee80211vap *vap,
ieee80211_scan_iter_func *f, void *arg)
{
struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
if (ss->ss_ops != NULL)
ss->ss_ops->scan_iterate(ss, f, arg);
}
/*
* Flush the contents of the scan cache.
*/
void
ieee80211_scan_flush(struct ieee80211vap *vap)
{
struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
if (ss->ss_ops != NULL && ss->ss_vap == vap) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN, "%s\n", __func__);
ss->ss_ops->scan_flush(ss);
}
}
/*
* Check the scan cache for an ap/channel to use; if that
* fails then kick off a new scan.
*/
struct ieee80211_channel *
ieee80211_scan_pickchannel(struct ieee80211com *ic, int flags)
{
struct ieee80211_scan_state *ss = ic->ic_scan;
IEEE80211_LOCK_ASSERT(ic);
if (ss == NULL || ss->ss_ops == NULL || ss->ss_vap == NULL) {
/* XXX printf? */
return NULL;
}
if (ss->ss_ops->scan_pickchan == NULL) {
IEEE80211_DPRINTF(ss->ss_vap, IEEE80211_MSG_SCAN,
"%s: scan module does not support picking a channel, "
"opmode %s\n", __func__, ss->ss_vap->iv_opmode);
return NULL;
}
return ss->ss_ops->scan_pickchan(ss, flags);
}
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