ieee80211softmac_assoc.c

linux 内核源代码

/*
 * This file contains the softmac's association logic.
 *
 * Copyright (c) 2005, 2006 Johannes Berg <[e-mail]>
 *                          Joseph Jezak <[e-mail]>
 *                          Larry Finger <[e-mail]>
 *                          Danny van Dyk <[e-mail]>
 *                          Michael Buesch <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 *
 * The full GNU General Public License is included in this distribution in the
 * file called COPYING.
 */

#include "ieee80211softmac_priv.h"

/*
 * Overview
 *
 * Before you can associate, you have to authenticate.
 *
 */

/* Sends out an association request to the desired AP */
static void
ieee80211softmac_assoc(struct ieee80211softmac_device *mac, struct ieee80211softmac_network *net)
{
	unsigned long flags;

	/* Switch to correct channel for this network */
	mac->set_channel(mac->dev, net->channel);

	/* Send association request */
	ieee80211softmac_send_mgt_frame(mac, net, IEEE80211_STYPE_ASSOC_REQ, 0);

	dprintk(KERN_INFO PFX "sent association request!\n");

	spin_lock_irqsave(&mac->lock, flags);
	mac->associnfo.associated = 0; /* just to make sure */

	/* Set a timer for timeout */
	/* FIXME: make timeout configurable */
	if (likely(mac->running))
		queue_delayed_work(mac->wq, &mac->associnfo.timeout, 5 * HZ);
	spin_unlock_irqrestore(&mac->lock, flags);
}

void
ieee80211softmac_assoc_timeout(struct work_struct *work)
{
	struct ieee80211softmac_device *mac =
		container_of(work, struct ieee80211softmac_device,
			     associnfo.timeout.work);
	struct ieee80211softmac_network *n;

	mutex_lock(&mac->associnfo.mutex);
	/* we might race against ieee80211softmac_handle_assoc_response,
	 * so make sure only one of us does something */
	if (!mac->associnfo.associating)
		goto out;
	mac->associnfo.associating = 0;
	mac->associnfo.bssvalid = 0;
	mac->associnfo.associated = 0;

	n = ieee80211softmac_get_network_by_bssid_locked(mac, mac->associnfo.bssid);

	dprintk(KERN_INFO PFX "assoc request timed out!\n");
	ieee80211softmac_call_events(mac, IEEE80211SOFTMAC_EVENT_ASSOCIATE_TIMEOUT, n);
out:
	mutex_unlock(&mac->associnfo.mutex);
}

void
ieee80211softmac_disassoc(struct ieee80211softmac_device *mac)
{
	unsigned long flags;

	spin_lock_irqsave(&mac->lock, flags);
	if (mac->associnfo.associating)
		cancel_delayed_work(&mac->associnfo.timeout);

	netif_carrier_off(mac->dev);

	mac->associnfo.associated = 0;
	mac->associnfo.bssvalid = 0;
	mac->associnfo.associating = 0;
	ieee80211softmac_init_bss(mac);
	ieee80211softmac_call_events_locked(mac, IEEE80211SOFTMAC_EVENT_DISASSOCIATED, NULL);
	spin_unlock_irqrestore(&mac->lock, flags);
}

/* Sends out a disassociation request to the desired AP */
void
ieee80211softmac_send_disassoc_req(struct ieee80211softmac_device *mac, u16 reason)
{
	struct ieee80211softmac_network *found;

	if (mac->associnfo.bssvalid && mac->associnfo.associated) {
		found = ieee80211softmac_get_network_by_bssid(mac, mac->associnfo.bssid);
		if (found)
			ieee80211softmac_send_mgt_frame(mac, found, IEEE80211_STYPE_DISASSOC, reason);
	}

	ieee80211softmac_disassoc(mac);
}

static inline int
we_support_all_basic_rates(struct ieee80211softmac_device *mac, u8 *from, u8 from_len)
{
	int idx;
	u8 rate;

	for (idx = 0; idx < (from_len); idx++) {
		rate = (from)[idx];
		if (!(rate & IEEE80211_BASIC_RATE_MASK))
			continue;
		rate &= ~IEEE80211_BASIC_RATE_MASK;
		if (!ieee80211softmac_ratesinfo_rate_supported(&mac->ratesinfo, rate))
			return 0;
	}
	return 1;
}

static int
network_matches_request(struct ieee80211softmac_device *mac, struct ieee80211_network *net)
{
	/* we cannot associate to networks whose name we don't know */
	if (ieee80211_is_empty_essid(net->ssid, net->ssid_len))
		return 0;
	/* do not associate to a network whose BSSBasicRateSet we cannot support */
	if (!we_support_all_basic_rates(mac, net->rates, net->rates_len))
		return 0;
	/* do we really need to check the ex rates? */
	if (!we_support_all_basic_rates(mac, net->rates_ex, net->rates_ex_len))
		return 0;

	/* assume that users know what they're doing ...
	 * (note we don't let them select a net we're incompatible with) */
	if (mac->associnfo.bssfixed) {
		return !memcmp(mac->associnfo.bssid, net->bssid, ETH_ALEN);
	}

	/* if 'ANY' network requested, take any that doesn't have privacy enabled */
	if (mac->associnfo.req_essid.len == 0
	    && !(net->capability & WLAN_CAPABILITY_PRIVACY))
		return 1;
	if (net->ssid_len != mac->associnfo.req_essid.len)
		return 0;
	if (!memcmp(net->ssid, mac->associnfo.req_essid.data, mac->associnfo.req_essid.len))
		return 1;
	return 0;
}

static void
ieee80211softmac_assoc_notify_scan(struct net_device *dev, int event_type, void *context)
{
	struct ieee80211softmac_device *mac = ieee80211_priv(dev);
	ieee80211softmac_assoc_work(&mac->associnfo.work.work);
}

static void
ieee80211softmac_assoc_notify_auth(struct net_device *dev, int event_type, void *context)
{
	struct ieee80211softmac_device *mac = ieee80211_priv(dev);

	switch (event_type) {
	case IEEE80211SOFTMAC_EVENT_AUTHENTICATED:
		ieee80211softmac_assoc_work(&mac->associnfo.work.work);
		break;
	case IEEE80211SOFTMAC_EVENT_AUTH_FAILED:
	case IEEE80211SOFTMAC_EVENT_AUTH_TIMEOUT:
		ieee80211softmac_disassoc(mac);
		break;
	}
}

/* This function is called to handle userspace requests (asynchronously) */
void
ieee80211softmac_assoc_work(struct work_struct *work)
{
	struct ieee80211softmac_device *mac =
		container_of(work, struct ieee80211softmac_device,
			     associnfo.work.work);
	struct ieee80211softmac_network *found = NULL;
	struct ieee80211_network *net = NULL, *best = NULL;
	int bssvalid;
	unsigned long flags;

	mutex_lock(&mac->associnfo.mutex);

	if (!mac->associnfo.associating)
		goto out;

	/* ieee80211_disassoc might clear this */
	bssvalid = mac->associnfo.bssvalid;

	/* meh */
	if (mac->associnfo.associated)
		ieee80211softmac_send_disassoc_req(mac, WLAN_REASON_DISASSOC_STA_HAS_LEFT);

	/* try to find the requested network in our list, if we found one already */
	if (bssvalid || mac->associnfo.bssfixed)
		found = ieee80211softmac_get_network_by_bssid(mac, mac->associnfo.bssid);

	/* Search the ieee80211 networks for this network if we didn't find it by bssid,
	 * but only if we've scanned at least once (to get a better list of networks to
	 * select from). If we have not scanned before, the !found logic below will be
	 * invoked and will scan. */
	if (!found && (mac->associnfo.scan_retry < IEEE80211SOFTMAC_ASSOC_SCAN_RETRY_LIMIT))
	{
		s8 rssi = -128;	/* if I don't initialise, gcc emits an invalid warning
				   because it cannot follow the best pointer logic. */
		spin_lock_irqsave(&mac->ieee->lock, flags);
		list_for_each_entry(net, &mac->ieee->network_list, list) {
			/* we're supposed to find the network with
			 * the best signal here, as we're asked to join
			 * any network with a specific ESSID, and many
			 * different ones could have that.
			 *
			 * I'll for now just go with the reported rssi.
			 *
			 * We also should take into account the rateset
			 * here to find the best BSSID to try.
			 */
			if (network_matches_request(mac, net)) {
				if (!best) {
					best = net;
					rssi = best->stats.rssi;
					continue;
				}
				/* we already had a matching network, so
				 * compare their properties to get the
				 * better of the two ... (see above)