ieee80211_beacon.c

Linux下wifi实现

	wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_MGT |
		IEEE80211_FC0_SUBTYPE_BEACON;
	wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
	*(u_int16_t *)wh->i_dur = 0;
	IEEE80211_ADDR_COPY(wh->i_addr1, ic->ic_dev->broadcast);
	IEEE80211_ADDR_COPY(wh->i_addr2, vap->iv_myaddr);
	IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
	*(u_int16_t *)wh->i_seq = 0;

	return skb;
}
EXPORT_SYMBOL(ieee80211_beacon_alloc);

/*
 * Update the dynamic parts of a beacon frame based on the current state.
 */
int
ieee80211_beacon_update(struct ieee80211_node *ni,
	struct ieee80211_beacon_offsets *bo, struct sk_buff *skb, int mcast)
{
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211com *ic = ni->ni_ic;
	int len_changed = 0;
	u_int16_t capinfo;

	IEEE80211_LOCK(ic);

	if ((ic->ic_flags & IEEE80211_F_DOTH) &&
	    (vap->iv_flags & IEEE80211_F_CHANSWITCH) &&
	    (vap->iv_chanchange_count == ic->ic_chanchange_tbtt)) {
		u_int8_t *frm;
		struct ieee80211_channel *c;

		vap->iv_chanchange_count = 0;

		IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
			"%s: reinit beacon\n", __func__);

		/* 
		 * NB: ic_bsschan is in the DSPARMS beacon IE, so must set this
		 *     prior to the beacon re-init, below.
		 */
		c = ieee80211_doth_findchan(vap, ic->ic_chanchange_chan);
		if (c == NULL) {
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
				"%s: find channel failure\n", __func__);
			return 0;
		}
		ic->ic_bsschan = c;

		skb_pull(skb, sizeof(struct ieee80211_frame));
		skb_trim(skb, 0);
		frm = skb->data;
		skb_put(skb, ieee80211_beacon_init(ni, bo, frm) - frm); 
		skb_push(skb, sizeof(struct ieee80211_frame));

		vap->iv_flags &= ~IEEE80211_F_CHANSWITCH;
		ic->ic_flags &= ~IEEE80211_F_CHANSWITCH;

		/* NB: only for the first VAP to get here */
		if (ic->ic_curchan != c) {
			ic->ic_curchan = c;
			ic->ic_set_channel(ic);
		}

		len_changed = 1;
	}

	/* XXX faster to recalculate entirely or just changes? */
	if (vap->iv_opmode == IEEE80211_M_IBSS)
		capinfo = IEEE80211_CAPINFO_IBSS;
	else
		capinfo = IEEE80211_CAPINFO_ESS;
	if (vap->iv_flags & IEEE80211_F_PRIVACY)
		capinfo |= IEEE80211_CAPINFO_PRIVACY;
	if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
	    IEEE80211_IS_CHAN_2GHZ(ic->ic_bsschan))
		capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
	if (ic->ic_flags & IEEE80211_F_SHSLOT)
		capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
	if (ic->ic_flags & IEEE80211_F_DOTH)
		capinfo |= IEEE80211_CAPINFO_SPECTRUM_MGMT;

	*bo->bo_caps = htole16(capinfo);

	if (vap->iv_flags & IEEE80211_F_WME) {
		struct ieee80211_wme_state *wme = &ic->ic_wme;

		/*
		 * Check for agressive mode change.  When there is
		 * significant high priority traffic in the BSS
		 * throttle back BE traffic by using conservative
		 * parameters.  Otherwise BE uses agressive params
		 * to optimize performance of legacy/non-QoS traffic.
		 */
		if (wme->wme_flags & WME_F_AGGRMODE) {
			if (wme->wme_hipri_traffic >
			    wme->wme_hipri_switch_thresh) {
				IEEE80211_NOTE(vap, IEEE80211_MSG_WME, ni,
					"%s: traffic %u, disable aggressive mode",
					__func__, wme->wme_hipri_traffic);
				wme->wme_flags &= ~WME_F_AGGRMODE;
				ieee80211_wme_updateparams_locked(vap);
				wme->wme_hipri_traffic =
					wme->wme_hipri_switch_hysteresis;
			} else
				wme->wme_hipri_traffic = 0;
		} else {
			if (wme->wme_hipri_traffic <=
			    wme->wme_hipri_switch_thresh) {
				IEEE80211_NOTE(vap, IEEE80211_MSG_WME, ni,
					"%s: traffic %u, enable aggressive mode",
					__func__, wme->wme_hipri_traffic);
				wme->wme_flags |= WME_F_AGGRMODE;
				ieee80211_wme_updateparams_locked(vap);
				wme->wme_hipri_traffic = 0;
			} else
				wme->wme_hipri_traffic =
					wme->wme_hipri_switch_hysteresis;
		}
		/* XXX multi-bss */
		if (vap->iv_flags & IEEE80211_F_WMEUPDATE) {
			(void) ieee80211_add_wme_param(bo->bo_wme, wme, IEEE80211_VAP_UAPSD_ENABLED(vap));
			vap->iv_flags &= ~IEEE80211_F_WMEUPDATE;
		}
	}

	if (vap->iv_opmode == IEEE80211_M_HOSTAP) {	/* NB: no IBSS support*/
		struct ieee80211_tim_ie *tie =
			(struct ieee80211_tim_ie *) bo->bo_tim;
		if (vap->iv_flags & IEEE80211_F_TIMUPDATE) {
			u_int timlen, timoff, i;
			/*
			 * ATIM/DTIM needs updating.  If it fits in the
			 * current space allocated then just copy in the
			 * new bits.  Otherwise we need to move any trailing
			 * data to make room.  Note that we know there is
			 * contiguous space because ieee80211_beacon_allocate
			 * ensures there is space in the mbuf to write a
			 * maximal-size virtual bitmap (based on ic_max_aid).
			 */
			/*
			 * Calculate the bitmap size and offset, copy any
			 * trailer out of the way, and then copy in the
			 * new bitmap and update the information element.
			 * Note that the tim bitmap must contain at least
			 * one byte and any offset must be even.
			 */
			if (vap->iv_ps_pending != 0) {
				timoff = 128;		/* impossibly large */
				for (i = 0; i < vap->iv_tim_len; i++)
					if (vap->iv_tim_bitmap[i]) {
						timoff = i &~ 1;
						break;
					}
				KASSERT(timoff != 128, ("tim bitmap empty!"));
				for (i = vap->iv_tim_len-1; i >= timoff; i--)
					if (vap->iv_tim_bitmap[i])
						break;
				timlen = 1 + (i - timoff);
			} else {
				timoff = 0;
				timlen = 1;
			}
			if (timlen != bo->bo_tim_len) {
				/* copy up/down trailer */
				int trailer_adjust =
					(tie->tim_bitmap+timlen) - (bo->bo_tim_trailer);
				memmove(tie->tim_bitmap+timlen, bo->bo_tim_trailer,
					bo->bo_tim_trailerlen);
				bo->bo_tim_trailer = tie->tim_bitmap+timlen;
				bo->bo_chanswitch += trailer_adjust;
				bo->bo_wme += trailer_adjust;
				bo->bo_erp += trailer_adjust;
				bo->bo_ath_caps += trailer_adjust;
				bo->bo_xr += trailer_adjust;
				if (timlen > bo->bo_tim_len)
					skb_put(skb, timlen - bo->bo_tim_len);
				else
					skb_trim(skb, skb->len - (bo->bo_tim_len - timlen));
				bo->bo_tim_len = timlen;

				/* update information element */
				tie->tim_len = 3 + timlen;
				tie->tim_bitctl = timoff;
				len_changed = 1;
			}
			memcpy(tie->tim_bitmap, vap->iv_tim_bitmap + timoff,
				bo->bo_tim_len);

			vap->iv_flags &= ~IEEE80211_F_TIMUPDATE;

			IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
				"%s: TIM updated, pending %u, off %u, len %u",
				__func__, vap->iv_ps_pending, timoff, timlen);
		}
		/* count down DTIM period */
		if (tie->tim_count == 0)
			tie->tim_count = tie->tim_period - 1;
		else
			tie->tim_count--;
		/* update state for buffered multicast frames on DTIM */
		if (mcast && (tie->tim_count == 0))
			tie->tim_bitctl |= 1;
		else
			tie->tim_bitctl &= ~1;

		if ((ic->ic_flags & IEEE80211_F_DOTH) &&
		    (ic->ic_flags & IEEE80211_F_CHANSWITCH)) {

			if (!vap->iv_chanchange_count) {
				vap->iv_flags |= IEEE80211_F_CHANSWITCH;

				/* copy out trailer to open up a slot */
				memmove(bo->bo_chanswitch + IEEE80211_CHANSWITCHANN_BYTES, 
					bo->bo_chanswitch, bo->bo_chanswitch_trailerlen);

				/* add ie in opened slot */
				bo->bo_chanswitch[0] = IEEE80211_ELEMID_CHANSWITCHANN;
				bo->bo_chanswitch[1] = 3; /* fixed length */
				bo->bo_chanswitch[2] = 1; /* stas get off for now */
				bo->bo_chanswitch[3] = ic->ic_chanchange_chan;
				bo->bo_chanswitch[4] = ic->ic_chanchange_tbtt;

				/* update the trailer lens */
				bo->bo_chanswitch_trailerlen += IEEE80211_CHANSWITCHANN_BYTES;
				bo->bo_tim_trailerlen += IEEE80211_CHANSWITCHANN_BYTES;
				bo->bo_wme += IEEE80211_CHANSWITCHANN_BYTES;
				bo->bo_erp += IEEE80211_CHANSWITCHANN_BYTES;
				bo->bo_ath_caps += IEEE80211_CHANSWITCHANN_BYTES;
				bo->bo_xr += IEEE80211_CHANSWITCHANN_BYTES;

				/* indicate new beacon length so other layers may manage memory */
				skb_put(skb, IEEE80211_CHANSWITCHANN_BYTES);
				len_changed = 1;
			}
			else
				bo->bo_chanswitch[4]--;
			vap->iv_chanchange_count++;
			IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
				"%s: CHANSWITCH IE, change in %d\n",
				__func__, bo->bo_chanswitch[4]);
		}
#ifdef ATH_SUPERG_XR
		if (vap->iv_flags & IEEE80211_F_XRUPDATE) {
			if (vap->iv_xrvap)
				(void) ieee80211_add_xr_param(bo->bo_xr, vap);
			vap->iv_flags &= ~IEEE80211_F_XRUPDATE;
		}
#endif
		if (ic->ic_flags_ext & IEEE80211_FEXT_ERPUPDATE) {
			(void) ieee80211_add_erp(bo->bo_erp, ic);
			ic->ic_flags_ext &= ~IEEE80211_FEXT_ERPUPDATE;
		}
	}
	/* if it is a mode change beacon for dynamic turbo case */
	if (((ic->ic_ath_cap & IEEE80211_ATHC_BOOST) != 0) ^
	    IEEE80211_IS_CHAN_TURBO(ic->ic_curchan))
		ieee80211_add_athAdvCap(bo->bo_ath_caps, vap->iv_bss->ni_ath_flags,
			vap->iv_bss->ni_ath_defkeyindex);
	IEEE80211_UNLOCK(ic);

	return len_changed;
}
EXPORT_SYMBOL(ieee80211_beacon_update);