/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2007-2008 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>
#ifdef __FreeBSD__
__FBSDID("$FreeBSD$");
#endif
/*
* IEEE 802.11 DFS/Radar support.
*/
#include "opt_inet.h"
#include "opt_wlan.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/endian.h>
#include <sys/errno.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_media.h>
#include <net/ethernet.h>
#include <net80211/ieee80211_var.h>
static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
&ieee80211_nol_timeout, 0, "NOL timeout (secs)");
#define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
static int ieee80211_cac_timeout = 60; /* 60 seconds */
SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
&ieee80211_cac_timeout, 0, "CAC timeout (secs)");
#define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
/*
DFS* In order to facilitate debugging, a couple of operating
* modes aside from the default are needed.
*
* 0 - default CAC/NOL behaviour - ie, start CAC, place
* channel on NOL list.
* 1 - send CAC, but don't change channel or add the channel
* to the NOL list.
* 2 - just match on radar, don't send CAC or place channel in
* the NOL list.
*/
static int ieee80211_dfs_debug = DFS_DBG_NONE;
/*
* This option must not be included in the default kernel
* as it allows users to plainly disable CAC/NOL handling.
*/
#ifdef IEEE80211_DFS_DEBUG
SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW,
&ieee80211_dfs_debug, 0, "DFS debug behaviour");
#endif
static int
null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm)
{
return ENOSYS;
}
void
ieee80211_dfs_attach(struct ieee80211com *ic)
{
struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
ic->ic_set_quiet = null_set_quiet;
}
void
ieee80211_dfs_detach(struct ieee80211com *ic)
{
/* NB: we assume no locking is needed */
ieee80211_dfs_reset(ic);
}
void
ieee80211_dfs_reset(struct ieee80211com *ic)
{
struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
int i;
/* NB: we assume no locking is needed */
/* NB: cac_timer should be cleared by the state machine */
callout_drain(&dfs->nol_timer);
for (i = 0; i < ic->ic_nchans; i++)
ic->ic_channels[i].ic_state = 0;
dfs->lastchan = NULL;
}
static void
cac_timeout(void *arg)
{
struct ieee80211vap *vap = arg;
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
int i;
IEEE80211_LOCK_ASSERT(ic);
if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
return;
/*
* When radar is detected during a CAC we are woken
* up prematurely to switch to a new channel.
* Check the channel to decide how to act.
*/
if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
ieee80211_notify_cac(ic, ic->ic_curchan,
IEEE80211_NOTIFY_CAC_RADAR);
if_printf(vap->iv_ifp,
"CAC timer on channel %u (%u MHz) stopped due to radar\n",
ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
/* XXX clobbers any existing desired channel */
/* NB: dfs->newchan may be NULL, that's ok */
vap->iv_des_chan = dfs->newchan;
ieee80211_new_state_locked(vap, IEEE80211_S_SCAN, 0);
} else {
if_printf(vap->iv_ifp,
"CAC timer on channel %u (%u MHz) expired; "
"no radar detected\n",
ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
/*
* Mark all channels with the current frequency
* as having completed CAC; this keeps us from
* doing it again until we change channels.
*/
for (i = 0; i < ic->ic_nchans; i++) {
struct ieee80211_channel *c = &ic->ic_channels[i];
if (c->ic_freq == ic->ic_curchan->ic_freq)
c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
}
ieee80211_notify_cac(ic, ic->ic_curchan,
IEEE80211_NOTIFY_CAC_EXPIRE);
ieee80211_cac_completeswitch(vap);
}
}
/*
* Initiate the CAC timer. The driver is responsible
* for setting up the hardware to scan for radar on the
* channnel, we just handle timing things out.
*/
void
ieee80211_dfs_cac_start(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
IEEE80211_LOCK_ASSERT(ic);
callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
ticks_to_secs(CAC_TIMEOUT),
ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
}
/*
* Clear the CAC timer.
*/
void
ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
IEEE80211_LOCK_ASSERT(ic);
/* NB: racey but not important */
if (callout_pending(&dfs->cac_timer)) {
if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
ieee80211_notify_cac(ic, ic->ic_curchan,
IEEE80211_NOTIFY_CAC_STOP);
}
callout_stop(&dfs->cac_timer);
}
void
ieee80211_dfs_cac_clear(struct ieee80211com *ic,
const struct ieee80211_channel *chan)
{
int i;
for (i = 0; i < ic->ic_nchans; i++) {
struct ieee80211_channel *c = &ic->ic_channels[i];
if (c->ic_freq == chan->ic_freq)
c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
}
}
static void
dfs_timeout(void *arg)
{
struct ieee80211com *ic = arg;
struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
struct ieee80211_channel *c;
int i, oldest, now;
IEEE80211_LOCK_ASSERT(ic);
now = oldest = ticks;
for (i = 0; i < ic->ic_nchans; i++) {
c = &ic->ic_channels[i];
if (IEEE80211_IS_CHAN_RADAR(c)) {
if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
/*
* NB: do this here so we get only one
* msg instead of one for every channel
* table entry.
*/
ic_printf(ic, "radar on channel %u "
"(%u MHz) cleared after timeout\n",
c->ic_ieee, c->ic_freq);
/* notify user space */
c->ic_state &=
~IEEE80211_CHANSTATE_NORADAR;
ieee80211_notify_radar(ic, c);
}
} else if (dfs->nol_event[i] < oldest)
oldest = dfs->nol_event[i];
}
}
if (oldest != now) {
/* arrange to process next channel up for a status change */
callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now);
}
}
static void
announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan,
const struct ieee80211_channel *newchan)
{
if (newchan == NULL)
ic_printf(ic, "radar detected on channel %u (%u MHz)\n",
curchan->ic_ieee, curchan->ic_freq);
else
ic_printf(ic, "radar detected on channel %u (%u MHz), "
"moving to channel %u (%u MHz)\n",
curchan->ic_ieee, curchan->ic_freq,
newchan->ic_ieee, newchan->ic_freq);
}
/*
* Handle a radar detection event on a channel. The channel is
* added to the NOL list and we record the time of the event.
* Entries are aged out after NOL_TIMEOUT. If radar was
* detected while doing CAC we force a state/channel change.
* Otherwise radar triggers a channel switch using the CSA
* mechanism (when the channel is the bss channel).
*/
void
ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
{
struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
int i, now;
IEEE80211_LOCK_ASSERT(ic);
/*
* If doing DFS debugging (mode 2), don't bother
* running the rest of this function.
*
* Simply announce the presence of the radar and continue
* along merrily.
*/
if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) {
announce_radar(ic, chan, chan);
ieee80211_notify_radar(ic, chan);
return;
}
/*
* Don't mark the channel and don't put it into NOL
* if we're doing DFS debugging.
*/
if (ieee80211_dfs_debug == DFS_DBG_NONE) {
/*
* Mark all entries with this frequency. Notify user
* space and arrange for notification when the radar
* indication is cleared. Then kick the NOL processing
* thread if not already running.
*/
now = ticks;
for (i = 0; i < ic->ic_nchans; i++) {
struct ieee80211_channel *c = &ic->ic_channels[i];
if (c->ic_freq == chan->ic_freq) {
c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
c->ic_state |= IEEE80211_CHANSTATE_RADAR;
dfs->nol_event[i] = now;
}
}
ieee80211_notify_radar(ic, chan);
chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
if (!callout_pending(&dfs->nol_timer))
callout_reset(&dfs->nol_timer, NOL_TIMEOUT,
dfs_timeout, ic);
}
/*
* If radar is detected on the bss channel while
* doing CAC; force a state change by scheduling the
* callout to be dispatched asap. Otherwise, if this
* event is for the bss channel then we must quiet
* traffic and schedule a channel switch.
*
* Note this allows us to receive notification about
* channels other than the bss channel; not sure
* that can/will happen but it's simple to support.
*/
if (chan == ic->ic_bsschan) {
/* XXX need a way to defer to user app */
/*
* Don't flip over to a new channel if
* we are currently doing DFS debugging.
*/
if (ieee80211_dfs_debug == DFS_DBG_NONE)
dfs->newchan = ieee80211_dfs_pickchannel(ic);
else
dfs->newchan = chan;
announce_radar(ic, chan, dfs->newchan);
if (callout_pending(&dfs->cac_timer))
callout_schedule(&dfs->cac_timer, 0);
else if (dfs->newchan != NULL) {
/* XXX mode 1, switch count 2 */
/* XXX calculate switch count based on max
switch time and beacon interval? */
ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
} else {
/*
* Spec says to stop all transmissions and
* wait on the current channel for an entry
* on the NOL to expire.
*/
/*XXX*/
ic_printf(ic, "%s: No free channels; waiting for entry "
"on NOL to expire\n", __func__);
}
} else {
/*
* Issue rate-limited console msgs.
*/
if (dfs->lastchan != chan) {
dfs->lastchan = chan;
dfs->cureps = 0;
announce_radar(ic, chan, NULL);
} else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
announce_radar(ic, chan, NULL);
}
}
}
struct ieee80211_channel *
ieee80211_dfs_pickchannel(struct ieee80211com *ic)
{
struct ieee80211_channel *c;
int i, flags;
uint16_t v;
/*
* Consult the scan cache first.
*/
flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
/*
* XXX if curchan is HT this will never find a channel
* XXX 'cuz we scan only legacy channels
*/
c = ieee80211_scan_pickchannel(ic, flags);
if (c != NULL)
return c;
/*
* No channel found in scan cache; select a compatible
* one at random (skipping channels where radar has
* been detected).
*/
get_random_bytes(&v, sizeof(v));
v %= ic->ic_nchans;
for (i = v; i < ic->ic_nchans; i++) {
c = &ic->ic_channels[i];
if (!IEEE80211_IS_CHAN_RADAR(c) &&
(c->ic_flags & flags) == flags)
return c;
}
for (i = 0; i < v; i++) {
c = &ic->ic_channels[i];
if (!IEEE80211_IS_CHAN_RADAR(c) &&
(c->ic_flags & flags) == flags)
return c;
}
ic_printf(ic, "HELP, no channel located to switch to!\n");
return NULL;
}