sys/net80211/ieee80211_radiotap.c

/*-
 * Copyright (c) 2009 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: head/sys/net80211/ieee80211_radiotap.c 192468 2009-05-20 20:00:40Z sam $");

/*
 * IEEE 802.11 radiotap support.
 */
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/endian.h>
#include <sys/kernel.h>

#include <sys/socket.h>

#include <net/bpf.h>
#include <net/if.h>
#include <net/if_llc.h>
#include <net/if_media.h>

#include <net80211/ieee80211_var.h>

static int radiotap_offset(struct ieee80211_radiotap_header *, int);

void
ieee80211_radiotap_attach(struct ieee80211com *ic,
	struct ieee80211_radiotap_header *th, int tlen, uint32_t tx_radiotap,
	struct ieee80211_radiotap_header *rh, int rlen, uint32_t rx_radiotap)
{
#define	B(_v)	(1<<(_v))
	int off;

	th->it_len = htole16(roundup2(tlen, sizeof(uint32_t)));
	th->it_present = htole32(tx_radiotap);
	ic->ic_th = th;
	/* calculate offset to channel data */
	off = -1;
	if (tx_radiotap & B(IEEE80211_RADIOTAP_CHANNEL))
		off = radiotap_offset(th, IEEE80211_RADIOTAP_CHANNEL);
	else if (tx_radiotap & B(IEEE80211_RADIOTAP_XCHANNEL))
		off = radiotap_offset(th, IEEE80211_RADIOTAP_XCHANNEL);
	if (off == -1) {
		if_printf(ic->ic_ifp, "%s: no tx channel, radiotap 0x%x",
		    __func__, tx_radiotap);
		/* NB: we handle this case but data will have no chan spec */
	} else
		ic->ic_txchan = ((uint8_t *) th) + off;

	rh->it_len = htole16(roundup2(rlen, sizeof(uint32_t)));
	rh->it_present = htole32(rx_radiotap);
	ic->ic_rh = rh;
	/* calculate offset to channel data */
	off = -1;
	if (rx_radiotap & B(IEEE80211_RADIOTAP_CHANNEL))
		off = radiotap_offset(rh, IEEE80211_RADIOTAP_CHANNEL);
	else if (rx_radiotap & B(IEEE80211_RADIOTAP_XCHANNEL))
		off = radiotap_offset(rh, IEEE80211_RADIOTAP_XCHANNEL);
	if (off == -1) {
		if_printf(ic->ic_ifp, "%s: no rx channel, radiotap 0x%x",
		    __func__, rx_radiotap);
		/* NB: we handle this case but data will have no chan spec */
	} else
		ic->ic_rxchan = ((uint8_t *) rh) + off;
#undef B
}

void
ieee80211_radiotap_detach(struct ieee80211com *ic)
{
}

void
ieee80211_radiotap_vattach(struct ieee80211vap *vap)
{
	struct ieee80211com *ic = vap->iv_ic;
	struct ieee80211_radiotap_header *th = ic->ic_th;

	KASSERT(th != NULL, ("no radiotap setup"));

	/* radiotap DLT for raw 802.11 frames */
	bpfattach2(vap->iv_ifp, DLT_IEEE802_11_RADIO,
	    sizeof(struct ieee80211_frame) + le16toh(th->it_len),
	    &vap->iv_rawbpf);
}

void
ieee80211_radiotap_vdetach(struct ieee80211vap *vap)
{
	/* NB: bpfattach is called by ether_ifdetach and claims all taps */
}

static void
set_channel(void *p, const struct ieee80211_channel *c)
{
	struct {
		uint16_t	freq;
		uint16_t	flags;
	} *rc = p;

	rc->freq = htole16(c->ic_freq);
	rc->flags = htole16(c->ic_flags);
}

static void
set_xchannel(void *p, const struct ieee80211_channel *c)
{
	struct {
		uint32_t	flags;
		uint16_t	freq;
		uint8_t		ieee;
		uint8_t		maxpow;
	} *rc = p;

	rc->flags = htole32(c->ic_flags);
	rc->freq = htole16(c->ic_freq);
	rc->ieee = c->ic_ieee;
	rc->maxpow = c->ic_maxregpower;
}

/*
 * Update radiotap state on channel change.
 */
void
ieee80211_radiotap_chan_change(struct ieee80211com *ic)
{
	if (ic->ic_rxchan != NULL) {
		struct ieee80211_radiotap_header *rh = ic->ic_rh;

		if (rh->it_present & (1<<IEEE80211_RADIOTAP_XCHANNEL))
			set_xchannel(ic->ic_rxchan, ic->ic_curchan);
		else if (rh->it_present & (1<<IEEE80211_RADIOTAP_CHANNEL))
			set_channel(ic->ic_rxchan, ic->ic_curchan);
	}
	if (ic->ic_txchan != NULL) {
		struct ieee80211_radiotap_header *th = ic->ic_th;

		if (th->it_present & (1<<IEEE80211_RADIOTAP_XCHANNEL))
			set_xchannel(ic->ic_txchan, ic->ic_curchan);
		else if (th->it_present & (1<<IEEE80211_RADIOTAP_CHANNEL))
			set_channel(ic->ic_txchan, ic->ic_curchan);
	}
}

static void
dispatch_radiotap(struct ieee80211vap *vap0, struct mbuf *m,
	struct ieee80211_radiotap_header *rh)
{
	struct ieee80211com *ic = vap0->iv_ic;
	int len = le16toh(rh->it_len);

	if (ieee80211_radiotap_active_vap(vap0))
		bpf_mtap2(vap0->iv_rawbpf, rh, len, m);
	if (ic->ic_monvaps) {
		struct ieee80211vap *vap;
		TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
			if (vap->iv_opmode == IEEE80211_M_MONITOR &&
			    vap != vap0 && ieee80211_radiotap_active_vap(vap))
				bpf_mtap2(vap->iv_rawbpf, rh, len, m);
		}
	}
}

/*
 * Dispatch radiotap data for transmitted packet.
 */
void
ieee80211_radiotap_tx(struct ieee80211vap *vap0, struct mbuf *m)
{
	dispatch_radiotap(vap0, m, vap0->iv_ic->ic_th);
}

/*
 * Dispatch radiotap data for received packet.
 */
void
ieee80211_radiotap_rx(struct ieee80211vap *vap0, struct mbuf *m)
{
	dispatch_radiotap(vap0, m, vap0->iv_ic->ic_rh);
}

/*
 * Dispatch radiotap data for a packet received outside the normal
 * rx processing path; this is used, for example, to handle frames
 * received with errors that would otherwise be dropped.
 */
void
ieee80211_radiotap_rx_all(struct ieee80211com *ic, struct mbuf *m)
{
	struct ieee80211_radiotap_header *rh = ic->ic_rh;
	int len = le16toh(rh->it_len);
	struct ieee80211vap *vap;

	/* XXX locking? */
	TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
		if (ieee80211_radiotap_active_vap(vap))
			bpf_mtap2(vap->iv_rawbpf, rh, len, m);
	}
}

/*
 * Return the offset of the specified item in the radiotap
 * header description.  If the item is not present or is not
 * known -1 is returned.
 */
static int
radiotap_offset(struct ieee80211_radiotap_header *rh, int item)
{
	static const struct {
		size_t	align, width;
	} items[] = {
		[IEEE80211_RADIOTAP_TSFT] = {
		    .align	= sizeof(uint64_t),
		    .width	= sizeof(uint64_t),
		},
		[IEEE80211_RADIOTAP_FLAGS] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_RATE] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_CHANNEL] = {
		    .align	= sizeof(uint16_t),
		    .width	= 2*sizeof(uint16_t),
		},
		[IEEE80211_RADIOTAP_FHSS] = {
		    .align	= sizeof(uint16_t),
		    .width	= sizeof(uint16_t),
		},
		[IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_DBM_ANTNOISE] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_LOCK_QUALITY] = {
		    .align	= sizeof(uint16_t),
		    .width	= sizeof(uint16_t),
		},
		[IEEE80211_RADIOTAP_TX_ATTENUATION] = {
		    .align	= sizeof(uint16_t),
		    .width	= sizeof(uint16_t),
		},
		[IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = {
		    .align	= sizeof(uint16_t),
		    .width	= sizeof(uint16_t),
		},
		[IEEE80211_RADIOTAP_DBM_TX_POWER] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_ANTENNA] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_DB_ANTSIGNAL] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_DB_ANTNOISE] = {
		    .align	= sizeof(uint8_t),
		    .width	= sizeof(uint8_t),
		},
		[IEEE80211_RADIOTAP_XCHANNEL] = {
		    .align	= sizeof(uint32_t),
		    .width	= 2*sizeof(uint32_t),
		},
	};
	uint32_t present = le32toh(rh->it_present);
	int off, i;

	off = sizeof(struct ieee80211_radiotap_header);
	for (i = 0; i < IEEE80211_RADIOTAP_EXT; i++) {
		if ((present & (1<<i)) == 0)
			continue;
		if (items[i].align == 0) {
			/* NB: unidentified element, don't guess */
			printf("%s: unknown item %d\n", __func__, i);
			return -1;
		}
		off = roundup2(off, items[i].align);
		if (i == item) {
			if (off + items[i].width > le16toh(rh->it_len)) {
				/* NB: item does not fit in header data */
				printf("%s: item %d not in header data, "
				    "off %d width %zu len %d\n", __func__, i,
				    off, items[i].width, le16toh(rh->it_len));
				return -1;
			}
			return off;
		}
		off += items[i].width;
	}
	return -1;
}