ieee80211_input.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_input.c 1676 2006-07-06 03:23:08Z brian $
 */
#ifndef EXPORT_SYMTAB
#define	EXPORT_SYMTAB
#endif

/*
 * IEEE 802.11 input handling.
 */
#include <linux/config.h>
#include <linux/version.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/random.h>
#include <linux/if_vlan.h>
#include <net/iw_handler.h> /* wireless_send_event(..) */
#include <linux/wireless.h> /* SIOCGIWTHRSPY */
#include <linux/if_arp.h> /* ARPHRD_ETHER */

#include "if_llc.h"
#include "if_ethersubr.h"
#include "if_media.h"
#include "if_athproto.h"

#include <net80211/ieee80211_var.h>

#ifdef IEEE80211_DEBUG
/*
 * Decide if a received management frame should be
 * printed when debugging is enabled.  This filters some
 * of the less interesting frames that come frequently
 * (e.g. beacons).
 */
static __inline int
doprint(struct ieee80211vap *vap, int subtype)
{
	switch (subtype) {
	case IEEE80211_FC0_SUBTYPE_BEACON:
		return (vap->iv_ic->ic_flags & IEEE80211_F_SCAN);
	case IEEE80211_FC0_SUBTYPE_PROBE_REQ:
		return (vap->iv_opmode == IEEE80211_M_IBSS);
	}
	return 1;
}

/*
 * Emit a debug message about discarding a frame or information
 * element.  One format is for extracting the mac address from
 * the frame header; the other is for when a header is not
 * available or otherwise appropriate.
 */
#define	IEEE80211_DISCARD(_vap, _m, _wh, _type, _fmt, ...) do {		\
	if ((_vap)->iv_debug & (_m))					\
		ieee80211_discard_frame(_vap, _wh, _type, _fmt, __VA_ARGS__);\
} while (0)
#define	IEEE80211_DISCARD_IE(_vap, _m, _wh, _type, _fmt, ...) do {	\
	if ((_vap)->iv_debug & (_m))					\
		ieee80211_discard_ie(_vap, _wh, _type, _fmt, __VA_ARGS__);\
} while (0)
#define	IEEE80211_DISCARD_MAC(_vap, _m, _mac, _type, _fmt, ...) do {	\
	if ((_vap)->iv_debug & (_m))					\
		ieee80211_discard_mac(_vap, _mac, _type, _fmt, __VA_ARGS__);\
} while (0)

static const u_int8_t *ieee80211_getbssid(struct ieee80211vap *,
	const struct ieee80211_frame *);
static void ieee80211_discard_frame(struct ieee80211vap *,
	const struct ieee80211_frame *, const char *, const char *, ...);
static void ieee80211_discard_ie(struct ieee80211vap *,
	const struct ieee80211_frame *, const char *, const char *, ...);
static void ieee80211_discard_mac(struct ieee80211vap *,
	const u_int8_t mac[IEEE80211_ADDR_LEN], const char *,
	const char *, ...);
#else
#define	IEEE80211_DISCARD(_vap, _m, _wh, _type, _fmt, ...)
#define	IEEE80211_DISCARD_IE(_vap, _m, _wh, _type, _fmt, ...)
#define	IEEE80211_DISCARD_MAC(_vap, _m, _mac, _type, _fmt, ...)
#endif /* IEEE80211_DEBUG */

static struct sk_buff *ieee80211_defrag(struct ieee80211_node *,
	struct sk_buff *, int);
static void ieee80211_deliver_data(struct ieee80211_node *, struct sk_buff *);
static struct sk_buff *ieee80211_decap(struct ieee80211vap *,
	struct sk_buff *, int);
static void ieee80211_send_error(struct ieee80211_node *, const u_int8_t *,
	int, int);
static void ieee80211_recv_pspoll(struct ieee80211_node *, struct sk_buff *);
static int accept_data_frame(struct ieee80211vap *, struct ieee80211_node *,
	struct ieee80211_key *, struct sk_buff *, struct ether_header *);


#ifdef ATH_SUPERG_FF
static void athff_decap(struct sk_buff *);
#endif
#ifdef USE_HEADERLEN_RESV
static unsigned short ath_eth_type_trans(struct sk_buff *, struct net_device *);
#endif

/* Enhanced iwspy support */
#ifdef CONFIG_NET_WIRELESS
#if WIRELESS_EXT >= 16

#ifndef IW_QUAL_QUAL_UPDATED
#define IW_QUAL_QUAL_UPDATED	0x01
#define IW_QUAL_LEVEL_UPDATED	0x02
#define IW_QUAL_NOISE_UPDATED	0x04
#endif /* IW_QUAL_QUAL_UPDATED */

/**
 * This function is a clone of set_quality(..) in ieee80211_wireless.c
 */
static void
set_quality(struct iw_quality *iq, u_int rssi)
{
	iq->qual = rssi;
	/* NB: max is 94 because noise is hardcoded to 161 */
	if (iq->qual > 94)
		iq->qual = 94;

	iq->noise = 161;		/* -95dBm */
	iq->level = iq->noise + iq->qual;
	iq->updated = IW_QUAL_QUAL_UPDATED | IW_QUAL_LEVEL_UPDATED |
		IW_QUAL_NOISE_UPDATED;
}

/**
 * Given a node and the rssi value of a just received frame from the node, this
 * function checks if to raise an iwspy event because we iwspy the node and rssi
 * exceeds threshold (if active).
 * 
 * @param vap: vap
 * @param ni: sender node
 * @param rssi: rssi value of received frame
 */
static void
iwspy_event(struct ieee80211vap *vap, struct ieee80211_node *ni, u_int rssi)
{
	if (vap->iv_spy.thr_low && vap->iv_spy.num && ni && (rssi <
		vap->iv_spy.thr_low || rssi > vap->iv_spy.thr_high)) {
		int i;
		for (i = 0; i < vap->iv_spy.num; i++) {
			if (IEEE80211_ADDR_EQ(ni->ni_macaddr,
				&(vap->iv_spy.mac[i * IEEE80211_ADDR_LEN]))) {
					
				union iwreq_data wrq;
				struct iw_thrspy thr;
				IEEE80211_DPRINTF(vap, IEEE80211_MSG_DEBUG,
					"%s: we spy %s, threshold is active "
					"and rssi exceeds it -> raise an iwspy"
					" event\n", __func__, ether_sprintf(
					 ni->ni_macaddr));
				memset(&wrq, 0, sizeof(wrq));
				wrq.data.length = 1;
				memset(&thr, 0, sizeof(struct iw_thrspy));
				memcpy(thr.addr.sa_data, ni->ni_macaddr,
					IEEE80211_ADDR_LEN);
				thr.addr.sa_family = ARPHRD_ETHER;
				set_quality(&thr.qual, rssi);
				set_quality(&thr.low, vap->iv_spy.thr_low);
				set_quality(&thr.high, vap->iv_spy.thr_high);
				wireless_send_event(vap->iv_dev,
					SIOCGIWTHRSPY, &wrq, (char*) &thr);
				break;
			}
		}
	}
}

#else
#define iwspy_event(_vap, _ni, _rssi)
#endif /* WIRELESS_EXT >= 16 */
#else
#define iwspy_event(_vap, _ni, _rssi)
#endif /* CONFIG_NET_WIRELESS */

/*
 * Process a received frame.  The node associated with the sender
 * should be supplied.  If nothing was found in the node table then
 * the caller is assumed to supply a reference to ic_bss instead.
 * The RSSI and a timestamp are also supplied.  The RSSI data is used
 * during AP scanning to select a AP to associate with; it can have
 * any units so long as values have consistent units and higher values
 * mean ``better signal''.  The receive timestamp is currently not used
 * by the 802.11 layer.
 *
 * Context: softIRQ (tasklet)
 */
int
ieee80211_input(struct ieee80211_node *ni,
	struct sk_buff *skb, int rssi, u_int32_t rstamp)
{
#define	HAS_SEQ(type)	((type & 0x4) == 0)
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211com *ic = vap->iv_ic;
	struct ieee80211_node *ni_wds = NULL;
	struct net_device *dev = vap->iv_dev;
	struct ieee80211_frame *wh;
	struct ieee80211_key *key;
	struct ether_header *eh;
#ifdef ATH_SUPERG_FF
	struct llc *llc;
#endif
	int hdrspace;
	u_int8_t dir, type, subtype;
	u_int8_t *bssid;
	u_int16_t rxseq;

	KASSERT(ni != NULL, ("null node"));
	ni->ni_inact = ni->ni_inact_reload;

	KASSERT(skb->len >= sizeof(struct ieee80211_frame_min),
		("frame length too short: %u", skb->len));

	/* XXX adjust device in sk_buff? */

	type = -1;			/* undefined */
	/*
	 * In monitor mode, send everything directly to bpf.
	 * Also do not process frames w/o i_addr2 any further.
	 * XXX may want to include the CRC
	 */
	if (vap->iv_opmode == IEEE80211_M_MONITOR)
		goto out;

	if (skb->len < sizeof(struct ieee80211_frame_min)) {
		IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_ANY,
			ni->ni_macaddr, NULL,
			"too short (1): len %u", skb->len);
		vap->iv_stats.is_rx_tooshort++;
		goto out;
	}
	/*
	 * Bit of a cheat here, we use a pointer for a 3-address
	 * frame format but don't reference fields past outside
	 * ieee80211_frame_min w/o first validating the data is
	 * present.
	 */
	wh = (struct ieee80211_frame *)skb->data;

	if ((wh->i_fc[0] & IEEE80211_FC0_VERSION_MASK) !=
	    IEEE80211_FC0_VERSION_0) {
		IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_ANY,
			ni->ni_macaddr, NULL, "wrong version %x", wh->i_fc[0]);
		vap->iv_stats.is_rx_badversion++;
		goto err;
	}

	dir = wh->i_fc[1] & IEEE80211_FC1_DIR_MASK;
	type = wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK;
	subtype = wh->i_fc[0] & IEEE80211_FC0_SUBTYPE_MASK;
	if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
		switch (vap->iv_opmode) {
		case IEEE80211_M_STA:
			bssid = wh->i_addr2;
			if (!IEEE80211_ADDR_EQ(bssid, ni->ni_bssid)) {
				/* not interested in */
				IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
					bssid, NULL, "%s", "not to bss");
				vap->iv_stats.is_rx_wrongbss++;
				goto out;
			}
			iwspy_event(vap, ni, rssi);
			break;
		case IEEE80211_M_IBSS:
		case IEEE80211_M_AHDEMO:
			if (dir != IEEE80211_FC1_DIR_NODS)
				bssid = wh->i_addr1;
			else if (type == IEEE80211_FC0_TYPE_CTL)
				bssid = wh->i_addr1;
			else {
				if (skb->len < sizeof(struct ieee80211_frame)) {
					IEEE80211_DISCARD_MAC(vap,
						IEEE80211_MSG_ANY, ni->ni_macaddr,
						NULL, "too short (2): len %u",
						skb->len);
					vap->iv_stats.is_rx_tooshort++;
					goto out;
				}
				bssid = wh->i_addr3;
			}
			if (type == IEEE80211_FC0_TYPE_DATA &&
			    ni == vap->iv_bss) {
				/*
				 * Try to find sender in local node table.
				 */
				ni = ieee80211_find_node(ni->ni_table, wh->i_addr2);
				if (ni == NULL) {
					/*
					 * Fake up a node for this newly discovered
					 * member of the IBSS.  This should probably
					 * done after an ACL check.
					 */
					ni = ieee80211_fakeup_adhoc_node(vap,
							wh->i_addr2);
					if (ni == NULL) {
						/* NB: stat kept for alloc failure */
						goto err;
					}
				}
			}
			iwspy_event(vap, ni, rssi);
			break;
		case IEEE80211_M_HOSTAP:
			if (dir != IEEE80211_FC1_DIR_NODS)
				bssid = wh->i_addr1;
			else if (type == IEEE80211_FC0_TYPE_CTL)
				bssid = wh->i_addr1;
			else {
				if (skb->len < sizeof(struct ieee80211_frame)) {
					IEEE80211_DISCARD_MAC(vap,
						IEEE80211_MSG_ANY, ni->ni_macaddr,
						NULL, "too short (2): len %u",
						skb->len);
					vap->iv_stats.is_rx_tooshort++;
					goto out;
				}
				bssid = wh->i_addr3;
			}
			/*
			 * Validate the bssid.
			 */
#ifdef ATH_SUPERG_XR
			if (!IEEE80211_ADDR_EQ(bssid, vap->iv_bss->ni_bssid) &&
			    !IEEE80211_ADDR_EQ(bssid, dev->broadcast)) {
				/*
				 * allow MGT frames to vap->iv_xrvap.
				 * this will allow roaming between  XR and normal vaps
				 * without station dis associating from previous vap.
				 */
				if (!(vap->iv_xrvap && 
				    IEEE80211_ADDR_EQ(bssid, vap->iv_xrvap->iv_bss->ni_bssid) &&
				    type == IEEE80211_FC0_TYPE_MGT && 
				    ni != vap->iv_bss)) {
					/* not interested in */
					IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
						bssid, NULL, "%s", "not to bss or xrbss");
					vap->iv_stats.is_rx_wrongbss++;
					goto out;
				}
			}
#else
			if (!IEEE80211_ADDR_EQ(bssid, vap->iv_bss->ni_bssid) &&
			    !IEEE80211_ADDR_EQ(bssid, dev->broadcast)) {
				/* not interested in */
				IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
					bssid, NULL, "%s", "not to bss");
				vap->iv_stats.is_rx_wrongbss++;
				goto out;
			}

#endif
			break;
		case IEEE80211_M_WDS:
			if (skb->len < sizeof(struct ieee80211_frame_addr4)) {
				IEEE80211_DISCARD_MAC(vap,
					IEEE80211_MSG_ANY, ni->ni_macaddr,
					NULL, "too short (3): len %u",
					skb->len);
				vap->iv_stats.is_rx_tooshort++;
				goto out;
			}
			bssid = wh->i_addr1;
			if (!IEEE80211_ADDR_EQ(bssid, vap->iv_bss->ni_bssid) &&
			    !IEEE80211_ADDR_EQ(bssid, dev->broadcast)) {
				/* not interested in */
				IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
					bssid, NULL, "%s", "not to bss");
				vap->iv_stats.is_rx_wrongbss++;
				goto out;
			}
			if (!IEEE80211_ADDR_EQ(wh->i_addr2, vap->wds_mac)) {
				/* not interested in */
				IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
					wh->i_addr2, NULL, "%s", "not from DS");
				vap->iv_stats.is_rx_wrongbss++;
				goto out;	
			}
			break;
		default:
			/* XXX catch bad values */
			goto out;
		}
		ni->ni_rssi = rssi;
		ni->ni_rstamp = rstamp;
		ni->ni_last_rx = jiffies;
		if (HAS_SEQ(type)) {
			u_int8_t tid;
			if (IEEE80211_QOS_HAS_SEQ(wh)) {
				tid = ((struct ieee80211_qosframe *)wh)->
					i_qos[0] & IEEE80211_QOS_TID;
				if (TID_TO_WME_AC(tid) >= WME_AC_VI)
					ic->ic_wme.wme_hipri_traffic++;
				tid++;
			} else
				tid = 0;
			rxseq = le16toh(*(u_int16_t *)wh->i_seq);
			if ((wh->i_fc[1] & IEEE80211_FC1_RETRY) &&
			    IEEE80211_SEQ_LEQ(rxseq, ni->ni_rxseqs[tid])) {
				/* duplicate, discard */
				IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
					bssid, "duplicate",
					"seqno <%u,%u> fragno <%u,%u> tid %u",
					rxseq >> IEEE80211_SEQ_SEQ_SHIFT,
					ni->ni_rxseqs[tid] >>
						IEEE80211_SEQ_SEQ_SHIFT,
					rxseq & IEEE80211_SEQ_FRAG_MASK,
					ni->ni_rxseqs[tid] &
						IEEE80211_SEQ_FRAG_MASK,
					tid);
				vap->iv_stats.is_rx_dup++;
				IEEE80211_NODE_STAT(ni, rx_dup);
				goto out;
			}