440 lines
12 KiB
C
440 lines
12 KiB
C
/*-
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* Copyright (c) 2007-2008 Sam Leffler, Errno Consulting
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifdef __FreeBSD__
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__FBSDID("$FreeBSD$");
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#endif
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/*
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* IEEE 802.11 DFS/Radar support.
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*/
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#include "opt_inet.h"
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#include "opt_wlan.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <sys/malloc.h>
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#include <sys/kernel.h>
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#include <sys/socket.h>
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#include <sys/sockio.h>
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#include <sys/endian.h>
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#include <sys/errno.h>
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#include <sys/proc.h>
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#include <sys/sysctl.h>
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#include <net/if.h>
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#include <net/if_var.h>
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#include <net/if_media.h>
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#include <net/ethernet.h>
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#include <net80211/ieee80211_var.h>
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static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
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static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
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SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
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&ieee80211_nol_timeout, 0, "NOL timeout (secs)");
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#define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
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static int ieee80211_cac_timeout = 60; /* 60 seconds */
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SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
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&ieee80211_cac_timeout, 0, "CAC timeout (secs)");
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#define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
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/*
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DFS* In order to facilitate debugging, a couple of operating
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* modes aside from the default are needed.
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*
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* 0 - default CAC/NOL behaviour - ie, start CAC, place
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* channel on NOL list.
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* 1 - send CAC, but don't change channel or add the channel
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* to the NOL list.
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* 2 - just match on radar, don't send CAC or place channel in
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* the NOL list.
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*/
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static int ieee80211_dfs_debug = DFS_DBG_NONE;
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/*
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* This option must not be included in the default kernel
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* as it allows users to plainly disable CAC/NOL handling.
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*/
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#ifdef IEEE80211_DFS_DEBUG
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SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW,
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&ieee80211_dfs_debug, 0, "DFS debug behaviour");
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#endif
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static int
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null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm)
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{
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return ENOSYS;
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}
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void
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ieee80211_dfs_attach(struct ieee80211com *ic)
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{
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struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
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callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
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ic->ic_set_quiet = null_set_quiet;
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}
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void
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ieee80211_dfs_detach(struct ieee80211com *ic)
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{
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/* NB: we assume no locking is needed */
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ieee80211_dfs_reset(ic);
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}
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void
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ieee80211_dfs_reset(struct ieee80211com *ic)
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{
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struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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int i;
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/* NB: we assume no locking is needed */
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/* NB: cac_timer should be cleared by the state machine */
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callout_drain(&dfs->nol_timer);
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for (i = 0; i < ic->ic_nchans; i++)
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ic->ic_channels[i].ic_state = 0;
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dfs->lastchan = NULL;
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}
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static void
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cac_timeout(void *arg)
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{
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struct ieee80211vap *vap = arg;
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struct ieee80211com *ic = vap->iv_ic;
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struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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int i;
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IEEE80211_LOCK_ASSERT(ic);
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if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
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return;
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/*
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* When radar is detected during a CAC we are woken
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* up prematurely to switch to a new channel.
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* Check the channel to decide how to act.
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*/
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if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
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ieee80211_notify_cac(ic, ic->ic_curchan,
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IEEE80211_NOTIFY_CAC_RADAR);
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if_printf(vap->iv_ifp,
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"CAC timer on channel %u (%u MHz) stopped due to radar\n",
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ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
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/* XXX clobbers any existing desired channel */
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/* NB: dfs->newchan may be NULL, that's ok */
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vap->iv_des_chan = dfs->newchan;
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/* XXX recursive lock need ieee80211_new_state_locked */
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ieee80211_new_state(vap, IEEE80211_S_SCAN, 0);
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} else {
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if_printf(vap->iv_ifp,
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"CAC timer on channel %u (%u MHz) expired; "
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"no radar detected\n",
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ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
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/*
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* Mark all channels with the current frequency
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* as having completed CAC; this keeps us from
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* doing it again until we change channels.
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*/
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for (i = 0; i < ic->ic_nchans; i++) {
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struct ieee80211_channel *c = &ic->ic_channels[i];
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if (c->ic_freq == ic->ic_curchan->ic_freq)
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c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
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}
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ieee80211_notify_cac(ic, ic->ic_curchan,
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IEEE80211_NOTIFY_CAC_EXPIRE);
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ieee80211_cac_completeswitch(vap);
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}
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}
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/*
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* Initiate the CAC timer. The driver is responsible
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* for setting up the hardware to scan for radar on the
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* channnel, we just handle timing things out.
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*/
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void
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ieee80211_dfs_cac_start(struct ieee80211vap *vap)
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{
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struct ieee80211com *ic = vap->iv_ic;
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struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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IEEE80211_LOCK_ASSERT(ic);
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callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
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if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
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ticks_to_secs(CAC_TIMEOUT),
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ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
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ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
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}
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/*
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* Clear the CAC timer.
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*/
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void
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ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
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{
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struct ieee80211com *ic = vap->iv_ic;
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struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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IEEE80211_LOCK_ASSERT(ic);
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/* NB: racey but not important */
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if (callout_pending(&dfs->cac_timer)) {
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if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
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ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
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ieee80211_notify_cac(ic, ic->ic_curchan,
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IEEE80211_NOTIFY_CAC_STOP);
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}
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callout_stop(&dfs->cac_timer);
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}
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void
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ieee80211_dfs_cac_clear(struct ieee80211com *ic,
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const struct ieee80211_channel *chan)
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{
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int i;
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for (i = 0; i < ic->ic_nchans; i++) {
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struct ieee80211_channel *c = &ic->ic_channels[i];
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if (c->ic_freq == chan->ic_freq)
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c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
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}
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}
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static void
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dfs_timeout(void *arg)
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{
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struct ieee80211com *ic = arg;
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struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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struct ieee80211_channel *c;
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int i, oldest, now;
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IEEE80211_LOCK_ASSERT(ic);
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now = oldest = ticks;
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for (i = 0; i < ic->ic_nchans; i++) {
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c = &ic->ic_channels[i];
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if (IEEE80211_IS_CHAN_RADAR(c)) {
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if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
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c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
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if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
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/*
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* NB: do this here so we get only one
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* msg instead of one for every channel
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* table entry.
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*/
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ic_printf(ic, "radar on channel %u "
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"(%u MHz) cleared after timeout\n",
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c->ic_ieee, c->ic_freq);
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/* notify user space */
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c->ic_state &=
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~IEEE80211_CHANSTATE_NORADAR;
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ieee80211_notify_radar(ic, c);
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}
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} else if (dfs->nol_event[i] < oldest)
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oldest = dfs->nol_event[i];
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}
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}
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if (oldest != now) {
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/* arrange to process next channel up for a status change */
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callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now);
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}
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}
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static void
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announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan,
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const struct ieee80211_channel *newchan)
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{
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if (newchan == NULL)
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ic_printf(ic, "radar detected on channel %u (%u MHz)\n",
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curchan->ic_ieee, curchan->ic_freq);
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else
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ic_printf(ic, "radar detected on channel %u (%u MHz), "
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"moving to channel %u (%u MHz)\n",
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curchan->ic_ieee, curchan->ic_freq,
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newchan->ic_ieee, newchan->ic_freq);
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}
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/*
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* Handle a radar detection event on a channel. The channel is
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* added to the NOL list and we record the time of the event.
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* Entries are aged out after NOL_TIMEOUT. If radar was
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* detected while doing CAC we force a state/channel change.
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* Otherwise radar triggers a channel switch using the CSA
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* mechanism (when the channel is the bss channel).
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*/
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void
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ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
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{
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struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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int i, now;
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IEEE80211_LOCK_ASSERT(ic);
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/*
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* If doing DFS debugging (mode 2), don't bother
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* running the rest of this function.
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*
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* Simply announce the presence of the radar and continue
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* along merrily.
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*/
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if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) {
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announce_radar(ic, chan, chan);
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ieee80211_notify_radar(ic, chan);
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return;
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}
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/*
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* Don't mark the channel and don't put it into NOL
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* if we're doing DFS debugging.
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*/
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if (ieee80211_dfs_debug == DFS_DBG_NONE) {
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/*
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* Mark all entries with this frequency. Notify user
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* space and arrange for notification when the radar
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* indication is cleared. Then kick the NOL processing
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* thread if not already running.
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*/
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now = ticks;
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for (i = 0; i < ic->ic_nchans; i++) {
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struct ieee80211_channel *c = &ic->ic_channels[i];
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if (c->ic_freq == chan->ic_freq) {
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c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
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c->ic_state |= IEEE80211_CHANSTATE_RADAR;
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dfs->nol_event[i] = now;
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}
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}
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ieee80211_notify_radar(ic, chan);
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chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
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if (!callout_pending(&dfs->nol_timer))
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callout_reset(&dfs->nol_timer, NOL_TIMEOUT,
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dfs_timeout, ic);
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}
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/*
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* If radar is detected on the bss channel while
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* doing CAC; force a state change by scheduling the
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* callout to be dispatched asap. Otherwise, if this
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* event is for the bss channel then we must quiet
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* traffic and schedule a channel switch.
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*
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* Note this allows us to receive notification about
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* channels other than the bss channel; not sure
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* that can/will happen but it's simple to support.
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*/
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if (chan == ic->ic_bsschan) {
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/* XXX need a way to defer to user app */
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/*
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* Don't flip over to a new channel if
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* we are currently doing DFS debugging.
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*/
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if (ieee80211_dfs_debug == DFS_DBG_NONE)
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dfs->newchan = ieee80211_dfs_pickchannel(ic);
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else
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dfs->newchan = chan;
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announce_radar(ic, chan, dfs->newchan);
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if (callout_pending(&dfs->cac_timer))
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callout_schedule(&dfs->cac_timer, 0);
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else if (dfs->newchan != NULL) {
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/* XXX mode 1, switch count 2 */
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/* XXX calculate switch count based on max
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switch time and beacon interval? */
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ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
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} else {
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/*
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* Spec says to stop all transmissions and
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* wait on the current channel for an entry
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* on the NOL to expire.
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*/
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/*XXX*/
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ic_printf(ic, "%s: No free channels; waiting for entry "
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"on NOL to expire\n", __func__);
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}
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} else {
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/*
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* Issue rate-limited console msgs.
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*/
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if (dfs->lastchan != chan) {
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dfs->lastchan = chan;
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dfs->cureps = 0;
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announce_radar(ic, chan, NULL);
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} else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
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announce_radar(ic, chan, NULL);
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}
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}
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}
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struct ieee80211_channel *
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ieee80211_dfs_pickchannel(struct ieee80211com *ic)
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{
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struct ieee80211_channel *c;
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int i, flags;
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uint16_t v;
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/*
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* Consult the scan cache first.
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*/
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flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
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/*
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* XXX if curchan is HT this will never find a channel
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* XXX 'cuz we scan only legacy channels
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*/
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c = ieee80211_scan_pickchannel(ic, flags);
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if (c != NULL)
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return c;
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/*
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* No channel found in scan cache; select a compatible
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* one at random (skipping channels where radar has
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* been detected).
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*/
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get_random_bytes(&v, sizeof(v));
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v %= ic->ic_nchans;
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for (i = v; i < ic->ic_nchans; i++) {
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c = &ic->ic_channels[i];
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if (!IEEE80211_IS_CHAN_RADAR(c) &&
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(c->ic_flags & flags) == flags)
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return c;
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}
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for (i = 0; i < v; i++) {
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c = &ic->ic_channels[i];
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if (!IEEE80211_IS_CHAN_RADAR(c) &&
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(c->ic_flags & flags) == flags)
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return c;
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}
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ic_printf(ic, "HELP, no channel located to switch to!\n");
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return NULL;
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}
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