diff options
Diffstat (limited to 'sys/net80211/ieee80211_dfs.c')
| -rw-r--r-- | sys/net80211/ieee80211_dfs.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/sys/net80211/ieee80211_dfs.c b/sys/net80211/ieee80211_dfs.c new file mode 100644 index 0000000..0351cb8 --- /dev/null +++ b/sys/net80211/ieee80211_dfs.c @@ -0,0 +1,372 @@ +/*- + * 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_media.h> + +#include <net80211/ieee80211_var.h> + +MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state"); + +/* XXX public for sysctl hookup */ +int ieee80211_nol_timeout = 30*60; /* 30 minutes */ +#define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) +int ieee80211_cac_timeout = 60; /* 60 seconds */ +#define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) + +void +ieee80211_dfs_attach(struct ieee80211com *ic) +{ + struct ieee80211_dfs_state *dfs = &ic->ic_dfs; + + callout_init(&dfs->nol_timer, CALLOUT_MPSAFE); + callout_init(&dfs->cac_timer, CALLOUT_MPSAFE); +} + +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; + + 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(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); + } + /* XXX cannot use drain 'cuz holding a lock */ + 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(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_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT, + dfs_timeout, ic); + } + IEEE80211_UNLOCK(ic); +} + +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); + + /* + * 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 */ + dfs->newchan = ieee80211_dfs_pickchannel(ic); + + announce_radar(ic->ic_ifp, chan, dfs->newchan); + + if (callout_pending(&dfs->cac_timer)) + callout_reset(&dfs->nol_timer, 0, dfs_timeout, ic); + 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*/ + } + } 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; +} |
