ieee80211_beacon.c

Linux下wifi实现

/*-
 * Copyright (c) 2001 Atsushi Onoe
 * Copyright (c) 2002-2005 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * 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.
 *
 * $Id: ieee80211_beacon.c 1575 2006-05-19 20:42:19Z dyqith $
 */
#ifndef EXPORT_SYMTAB
#define	EXPORT_SYMTAB
#endif

/*
 * IEEE 802.11 beacon handling routines
 */
#include <linux/config.h>
#include <linux/version.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/if_vlan.h>

#include "if_media.h"
#include <net80211/ieee80211_var.h>

/* 
 *  XXX: Include an intra-module function from ieee80211_input.c.
 *       When we move regdomain code out to separate .h/.c files
 *       this should go to that .h file.
 */
struct ieee80211_channel *ieee80211_doth_findchan(struct ieee80211vap *, u_int8_t);


static u_int8_t *
ieee80211_beacon_init(struct ieee80211_node *ni, struct ieee80211_beacon_offsets *bo,
	u_int8_t *frm)
{
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211com *ic = ni->ni_ic;
	u_int16_t capinfo;
	struct ieee80211_rateset *rs = &ni->ni_rates;

	KASSERT(ic->ic_bsschan != IEEE80211_CHAN_ANYC, ("no bss chan"));

	/* XXX timestamp is set by hardware/driver */
	memset(frm, 0, 8);
	frm += 8;

	/* beacon interval */
	*(u_int16_t *)frm = htole16(ni->ni_intval);
	frm += 2;

	/* capability information */
	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 = (u_int16_t *)frm;
	*(u_int16_t *)frm = htole16(capinfo);
	frm += 2;

	/* ssid */
	*frm++ = IEEE80211_ELEMID_SSID;
	if ((vap->iv_flags & IEEE80211_F_HIDESSID) == 0) {
		*frm++ = ni->ni_esslen;
		memcpy(frm, ni->ni_essid, ni->ni_esslen);
		frm += ni->ni_esslen;
	} else
		*frm++ = 0;
	
	/* supported rates */
	frm = ieee80211_add_rates(frm, rs);


	/* XXX: better way to check this? */
	/* XXX: how about DS ? */
	if (!IEEE80211_IS_CHAN_FHSS(ic->ic_bsschan)) {
		*frm++ = IEEE80211_ELEMID_DSPARMS;
		*frm++ = 1;
		*frm++ = ieee80211_chan2ieee(ic, ic->ic_bsschan);
	}
	bo->bo_tim = frm;

	/* IBSS/TIM */
	if (vap->iv_opmode == IEEE80211_M_IBSS) {
		*frm++ = IEEE80211_ELEMID_IBSSPARMS;
		*frm++ = 2;
		*frm++ = 0; *frm++ = 0;		/* TODO: ATIM window */
		bo->bo_tim_len = 0;
	} else {
		struct ieee80211_tim_ie *tie = (struct ieee80211_tim_ie *) frm;

		tie->tim_ie = IEEE80211_ELEMID_TIM;
		tie->tim_len = 4;	/* length */
		tie->tim_count = 0;	/* DTIM count */
		tie->tim_period = vap->iv_dtim_period;	/* DTIM period */
		tie->tim_bitctl = 0;	/* bitmap control */
		tie->tim_bitmap[0] = 0;	/* Partial Virtual Bitmap */
		frm += sizeof(struct ieee80211_tim_ie);
		bo->bo_tim_len = 1;
	}
	bo->bo_tim_trailer = frm;

	/* country */
	if ((ic->ic_flags & IEEE80211_F_DOTH) || 
	    (ic->ic_flags_ext & IEEE80211_FEXT_COUNTRYIE)) {
		frm = ieee80211_add_country(frm, ic);
	}

	/* power constraint */
	if (ic->ic_flags & IEEE80211_F_DOTH) {
		*frm++ = IEEE80211_ELEMID_PWRCNSTR;
		*frm++ = 1;
		*frm++ = IEEE80211_PWRCONSTRAINT_VAL(ic);
	}

	/* XXX: channel switch announcement ? */ 
	bo->bo_chanswitch = frm;

	/* ERP */
	if (IEEE80211_IS_CHAN_ANYG(ic->ic_bsschan)) {
		bo->bo_erp = frm;
		frm = ieee80211_add_erp(frm, ic);
	}

	/* Ext. Supp. Rates */
	frm = ieee80211_add_xrates(frm, rs);

	/* WME */
	if (vap->iv_flags & IEEE80211_F_WME) {
		bo->bo_wme = frm;
		frm = ieee80211_add_wme_param(frm, &ic->ic_wme, IEEE80211_VAP_UAPSD_ENABLED(vap));
		vap->iv_flags &= ~IEEE80211_F_WMEUPDATE;
	}

	/* WPA 1+2 */
	if (vap->iv_flags & IEEE80211_F_WPA)
		frm = ieee80211_add_wpa(frm, vap);

	/* athAdvCaps */
	bo->bo_ath_caps = frm;
	if (vap->iv_bss && vap->iv_bss->ni_ath_flags)
		frm = ieee80211_add_athAdvCap(frm, vap->iv_bss->ni_ath_flags,
			vap->iv_bss->ni_ath_defkeyindex);
	
	/* XR */
	bo->bo_xr = frm;
#ifdef ATH_SUPERG_XR
	if (vap->iv_xrvap && vap->iv_ath_cap & IEEE80211_ATHC_XR)	/* XR */
		frm = ieee80211_add_xr_param(frm, vap);
#endif
	
	bo->bo_tim_trailerlen = frm - bo->bo_tim_trailer;
	bo->bo_chanswitch_trailerlen = frm - bo->bo_chanswitch;

	return frm;
}


/*
 * Allocate a beacon frame and fillin the appropriate bits.
 */
struct sk_buff *
ieee80211_beacon_alloc(struct ieee80211_node *ni,
	struct ieee80211_beacon_offsets *bo)
{
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211com *ic = ni->ni_ic;
	struct ieee80211_frame *wh;
	struct sk_buff *skb;
	int pktlen;
	u_int8_t *frm;
	struct ieee80211_rateset *rs;

	/*
	 * beacon frame format
	 *	[8] time stamp
	 *	[2] beacon interval
	 *	[2] cabability information
	 *	[tlv] ssid
	 *	[tlv] supported rates
	 *	[7] FH/DS parameter set
	 *	[tlv] IBSS/TIM parameter set
	 *	[tlv] country code 
	 *	[3] power constraint
	 *	[5] channel switch announcement
	 *	[3] extended rate phy (ERP)
	 *	[tlv] extended supported rates
	 *	[tlv] WME parameters
	 *	[tlv] WPA/RSN parameters
	 *	[tlv] Atheros Advanced Capabilities
	 *	[tlv] AtherosXR parameters
	 * XXX Vendor-specific OIDs (e.g. Atheros)
	 * NB: we allocate the max space required for the TIM bitmap.
	 */
	rs = &ni->ni_rates;
	pktlen =   8					/* time stamp */
		 + sizeof(u_int16_t)			/* beacon interval */
		 + sizeof(u_int16_t)			/* capability information */
		 + 2 + ni->ni_esslen			/* ssid */
	         + 2 + IEEE80211_RATE_SIZE		/* supported rates */
	         + 7 					/* FH/DS parameters max(7,3) */
		 + 2 + 4 + vap->iv_tim_len		/* IBSS/TIM parameter set*/
		 + ic->ic_country_ie.country_len + 2	/* country code */
	         + 3					/* power constraint */
	         + 5					/* channel switch announcement */
		 + 3					/* ERP */
	         + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE) /* Ext. Supp. Rates */
		 + (vap->iv_caps & IEEE80211_C_WME ?	/* WME */
			sizeof(struct ieee80211_wme_param) : 0)
		 + (vap->iv_caps & IEEE80211_C_WPA ?	/* WPA 1+2 */
			2 * sizeof(struct ieee80211_ie_wpa) : 0)
		 + sizeof(struct ieee80211_ie_athAdvCap)
#ifdef ATH_SUPERG_XR
		 + (ic->ic_ath_cap & IEEE80211_ATHC_XR ?	/* XR */
			sizeof(struct ieee80211_xr_param) : 0)
#endif
		 ;
	skb = ieee80211_getmgtframe(&frm, pktlen);
	if (skb == NULL) {
		IEEE80211_NOTE(vap, IEEE80211_MSG_ANY, ni,
			"%s: cannot get buf; size %u", __func__, pktlen);
		vap->iv_stats.is_tx_nobuf++;
		return NULL;
	}

	frm = ieee80211_beacon_init(ni, bo, frm);

	skb_trim(skb, frm - skb->data);

	wh = (struct ieee80211_frame *)
		skb_push(skb, sizeof(struct ieee80211_frame));