/*- * 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 #ifdef __FreeBSD__ __FBSDID("$FreeBSD$"); #endif /* * IEEE 802.11 DFS/Radar support. */ #include "opt_inet.h" #include "opt_wlan.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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; /* XXX recursive lock need ieee80211_new_state_locked */ ieee80211_new_state(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 (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. */ if_printf(ic->ic_ifp, "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 ifnet *ifp, const struct ieee80211_channel *curchan, const struct ieee80211_channel *newchan) { if (newchan == NULL) if_printf(ifp, "radar detected on channel %u (%u MHz)\n", curchan->ic_ieee, curchan->ic_freq); else if_printf(ifp, "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->ic_ifp, 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->ic_ifp, 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*/ if_printf(ic->ic_ifp, "%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->ic_ifp, chan, NULL); } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { announce_radar(ic->ic_ifp, 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; } if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n"); return NULL; }