net/mac80211/scan.c

/*
 * BSS client mode implementation
 * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/wireless.h>
#include <linux/if_arp.h>
#include <net/mac80211.h>
#include <net/iw_handler.h>

#include "ieee80211_i.h"

#define IEEE80211_PROBE_DELAY (HZ / 33)
#define IEEE80211_CHANNEL_TIME (HZ / 33)
#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)


ieee80211_rx_result
ieee80211_sta_rx_scan(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
		      struct ieee80211_rx_status *rx_status)
{
	struct ieee80211_mgmt *mgmt;
	struct ieee80211_sta_bss *bss;
	u8 *elements;
	struct ieee80211_channel *channel;
	size_t baselen;
	int freq;
	__le16 fc;
	bool presp, beacon = false;
	struct ieee802_11_elems elems;

	if (skb->len < 2)
		return RX_DROP_UNUSABLE;

	mgmt = (struct ieee80211_mgmt *) skb->data;
	fc = mgmt->frame_control;

	if (ieee80211_is_ctl(fc))
		return RX_CONTINUE;

	if (skb->len < 24)
		return RX_DROP_MONITOR;

	presp = ieee80211_is_probe_resp(fc);
	if (presp) {
		/* ignore ProbeResp to foreign address */
		if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
			return RX_DROP_MONITOR;

		presp = true;
		elements = mgmt->u.probe_resp.variable;
		baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
	} else {
		beacon = ieee80211_is_beacon(fc);
		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
		elements = mgmt->u.beacon.variable;
	}

	if (!presp && !beacon)
		return RX_CONTINUE;

	if (baselen > skb->len)
		return RX_DROP_MONITOR;

	ieee802_11_parse_elems(elements, skb->len - baselen, &elems);

	if (elems.ds_params && elems.ds_params_len == 1)
		freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
	else
		freq = rx_status->freq;

	channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);

	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
		return RX_DROP_MONITOR;

	bss = ieee80211_bss_info_update(sdata->local, rx_status,
					mgmt, skb->len, &elems,
					freq, beacon);
	ieee80211_rx_bss_put(sdata->local, bss);

	dev_kfree_skb(skb);
	return RX_QUEUED;
}

static void ieee80211_send_nullfunc(struct ieee80211_local *local,
				    struct ieee80211_sub_if_data *sdata,
				    int powersave)
{
	struct sk_buff *skb;
	struct ieee80211_hdr *nullfunc;
	__le16 fc;

	skb = dev_alloc_skb(local->hw.extra_tx_headroom + 24);
	if (!skb) {
		printk(KERN_DEBUG "%s: failed to allocate buffer for nullfunc "
		       "frame\n", sdata->dev->name);
		return;
	}
	skb_reserve(skb, local->hw.extra_tx_headroom);

	nullfunc = (struct ieee80211_hdr *) skb_put(skb, 24);
	memset(nullfunc, 0, 24);
	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_NULLFUNC |
			 IEEE80211_FCTL_TODS);
	if (powersave)
		fc |= cpu_to_le16(IEEE80211_FCTL_PM);
	nullfunc->frame_control = fc;
	memcpy(nullfunc->addr1, sdata->u.sta.bssid, ETH_ALEN);
	memcpy(nullfunc->addr2, sdata->dev->dev_addr, ETH_ALEN);
	memcpy(nullfunc->addr3, sdata->u.sta.bssid, ETH_ALEN);

	ieee80211_sta_tx(sdata, skb, 0);
}

static void ieee80211_restart_sta_timer(struct ieee80211_sub_if_data *sdata)
{
	if (sdata->vif.type == IEEE80211_IF_TYPE_STA ||
	    ieee80211_vif_is_mesh(&sdata->vif))
		ieee80211_sta_timer((unsigned long)sdata);
}

void ieee80211_scan_completed(struct ieee80211_hw *hw)
{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_sub_if_data *sdata;
	union iwreq_data wrqu;

	local->last_scan_completed = jiffies;
	memset(&wrqu, 0, sizeof(wrqu));
	wireless_send_event(local->scan_sdata->dev, SIOCGIWSCAN, &wrqu, NULL);

	if (local->sta_hw_scanning) {
		local->sta_hw_scanning = 0;
		if (ieee80211_hw_config(local))
			printk(KERN_DEBUG "%s: failed to restore operational "
			       "channel after scan\n", wiphy_name(local->hw.wiphy));
		/* Restart STA timer for HW scan case */
		rcu_read_lock();
		list_for_each_entry_rcu(sdata, &local->interfaces, list)
			ieee80211_restart_sta_timer(sdata);
		rcu_read_unlock();

		goto done;
	}

	local->sta_sw_scanning = 0;
	if (ieee80211_hw_config(local))
		printk(KERN_DEBUG "%s: failed to restore operational "
		       "channel after scan\n", wiphy_name(local->hw.wiphy));


	netif_tx_lock_bh(local->mdev);
	netif_addr_lock(local->mdev);
	local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
	local->ops->configure_filter(local_to_hw(local),
				     FIF_BCN_PRBRESP_PROMISC,
				     &local->filter_flags,
				     local->mdev->mc_count,
				     local->mdev->mc_list);

	netif_addr_unlock(local->mdev);
	netif_tx_unlock_bh(local->mdev);

	rcu_read_lock();
	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
		/* Tell AP we're back */
		if (sdata->vif.type == IEEE80211_IF_TYPE_STA) {
			if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
				ieee80211_send_nullfunc(local, sdata, 0);
				netif_tx_wake_all_queues(sdata->dev);
			}
		} else
			netif_tx_wake_all_queues(sdata->dev);

		ieee80211_restart_sta_timer(sdata);
	}
	rcu_read_unlock();

 done:
	ieee80211_mlme_notify_scan_completed(local);
}
EXPORT_SYMBOL(ieee80211_scan_completed);


void ieee80211_sta_scan_work(struct work_struct *work)
{
	struct ieee80211_local *local =
		container_of(work, struct ieee80211_local, scan_work.work);
	struct ieee80211_sub_if_data *sdata = local->scan_sdata;
	struct ieee80211_supported_band *sband;
	struct ieee80211_channel *chan;
	int skip;
	unsigned long next_delay = 0;

	if (!local->sta_sw_scanning)
		return;

	switch (local->scan_state) {
	case SCAN_SET_CHANNEL:
		/*
		 * Get current scan band. scan_band may be IEEE80211_NUM_BANDS
		 * after we successfully scanned the last channel of the last
		 * band (and the last band is supported by the hw)
		 */
		if (local->scan_band < IEEE80211_NUM_BANDS)
			sband = local->hw.wiphy->bands[local->scan_band];
		else
			sband = NULL;

		/*
		 * If we are at an unsupported band and have more bands
		 * left to scan, advance to the next supported one.
		 */
		while (!sband && local->scan_band < IEEE80211_NUM_BANDS - 1) {
			local->scan_band++;
			sband = local->hw.wiphy->bands[local->scan_band];
			local->scan_channel_idx = 0;
		}

		/* if no more bands/channels left, complete scan */
		if (!sband || local->scan_channel_idx >= sband->n_channels) {
			ieee80211_scan_completed(local_to_hw(local));
			return;
		}
		skip = 0;
		chan = &sband->channels[local->scan_channel_idx];

		if (chan->flags & IEEE80211_CHAN_DISABLED ||
		    (sdata->vif.type == IEEE80211_IF_TYPE_IBSS &&
		     chan->flags & IEEE80211_CHAN_NO_IBSS))
			skip = 1;

		if (!skip) {
			local->scan_channel = chan;
			if (ieee80211_hw_config(local)) {
				printk(KERN_DEBUG "%s: failed to set freq to "
				       "%d MHz for scan\n", wiphy_name(local->hw.wiphy),
				       chan->center_freq);
				skip = 1;
			}
		}

		/* advance state machine to next channel/band */
		local->scan_channel_idx++;
		if (local->scan_channel_idx >= sband->n_channels) {
			/*
			 * scan_band may end up == IEEE80211_NUM_BANDS, but
			 * we'll catch that case above and complete the scan
			 * if that is the case.
			 */
			local->scan_band++;
			local->scan_channel_idx = 0;
		}

		if (skip)
			break;

		next_delay = IEEE80211_PROBE_DELAY +
			     usecs_to_jiffies(local->hw.channel_change_time);
		local->scan_state = SCAN_SEND_PROBE;
		break;
	case SCAN_SEND_PROBE:
		next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
		local->scan_state = SCAN_SET_CHANNEL;

		if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN)
			break;
		ieee80211_send_probe_req(sdata, NULL, local->scan_ssid,
					 local->scan_ssid_len);
		next_delay = IEEE80211_CHANNEL_TIME;
		break;
	}

	if (local->sta_sw_scanning)
		queue_delayed_work(local->hw.workqueue, &local->scan_work,
				   next_delay);
}


int ieee80211_sta_start_scan(struct ieee80211_sub_if_data *scan_sdata,
			     u8 *ssid, size_t ssid_len)
{
	struct ieee80211_local *local = scan_sdata->local;
	struct ieee80211_sub_if_data *sdata;

	if (ssid_len > IEEE80211_MAX_SSID_LEN)
		return -EINVAL;

	/* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
	 * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
	 * BSSID: MACAddress
	 * SSID
	 * ScanType: ACTIVE, PASSIVE
	 * ProbeDelay: delay (in microseconds) to be used prior to transmitting
	 *    a Probe frame during active scanning
	 * ChannelList
	 * MinChannelTime (>= ProbeDelay), in TU
	 * MaxChannelTime: (>= MinChannelTime), in TU
	 */

	 /* MLME-SCAN.confirm
	  * BSSDescriptionSet
	  * ResultCode: SUCCESS, INVALID_PARAMETERS
	 */

	if (local->sta_sw_scanning || local->sta_hw_scanning) {
		if (local->scan_sdata == scan_sdata)
			return 0;
		return -EBUSY;
	}

	if (local->ops->hw_scan) {
		int rc = local->ops->hw_scan(local_to_hw(local),
					     ssid, ssid_len);
		if (!rc) {
			local->sta_hw_scanning = 1;
			local->scan_sdata = scan_sdata;
		}
		return rc;
	}

	local->sta_sw_scanning = 1;

	rcu_read_lock();
	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
		if (sdata->vif.type == IEEE80211_IF_TYPE_STA) {
			if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
				netif_tx_stop_all_queues(sdata->dev);
				ieee80211_send_nullfunc(local, sdata, 1);
			}
		} else
			netif_tx_stop_all_queues(sdata->dev);
	}
	rcu_read_unlock();

	if (ssid) {
		local->scan_ssid_len = ssid_len;
		memcpy(local->scan_ssid, ssid, ssid_len);
	} else
		local->scan_ssid_len = 0;
	local->scan_state = SCAN_SET_CHANNEL;
	local->scan_channel_idx = 0;
	local->scan_band = IEEE80211_BAND_2GHZ;
	local->scan_sdata = scan_sdata;

	netif_addr_lock_bh(local->mdev);
	local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
	local->ops->configure_filter(local_to_hw(local),
				     FIF_BCN_PRBRESP_PROMISC,
				     &local->filter_flags,
				     local->mdev->mc_count,
				     local->mdev->mc_list);
	netif_addr_unlock_bh(local->mdev);

	/* TODO: start scan as soon as all nullfunc frames are ACKed */
	queue_delayed_work(local->hw.workqueue, &local->scan_work,
			   IEEE80211_CHANNEL_TIME);

	return 0;
}


int ieee80211_sta_req_scan(struct ieee80211_sub_if_data *sdata, u8 *ssid, size_t ssid_len)
{
	struct ieee80211_if_sta *ifsta = &sdata->u.sta;
	struct ieee80211_local *local = sdata->local;

	if (sdata->vif.type != IEEE80211_IF_TYPE_STA)
		return ieee80211_sta_start_scan(sdata, ssid, ssid_len);

	if (local->sta_sw_scanning || local->sta_hw_scanning) {
		if (local->scan_sdata == sdata)
			return 0;
		return -EBUSY;
	}

	ifsta->scan_ssid_len = ssid_len;
	if (ssid_len)
		memcpy(ifsta->scan_ssid, ssid, ssid_len);
	set_bit(IEEE80211_STA_REQ_SCAN, &ifsta->request);
	queue_work(local->hw.workqueue, &ifsta->work);
	return 0;
}


static void ieee80211_sta_add_scan_ies(struct iw_request_info *info,
				       struct ieee80211_sta_bss *bss,
				       char **current_ev, char *end_buf)
{
	u8 *pos, *end, *next;
	struct iw_event iwe;

	if (bss == NULL || bss->ies == NULL)
		return;

	/*
	 * If needed, fragment the IEs buffer (at IE boundaries) into short
	 * enough fragments to fit into IW_GENERIC_IE_MAX octet messages.
	 */
	pos = bss->ies;
	end = pos + bss->ies_len;

	while (end - pos > IW_GENERIC_IE_MAX) {
		next = pos + 2 + pos[1];
		while (next + 2 + next[1] - pos < IW_GENERIC_IE_MAX)
			next = next + 2 + next[1];

		memset(&iwe, 0, sizeof(iwe));
		iwe.cmd = IWEVGENIE;
		iwe.u.data.length = next - pos;
		*current_ev = iwe_stream_add_point(info, *current_ev,
						   end_buf, &iwe, pos);

		pos = next;
	}

	if (end > pos) {
		memset(&iwe, 0, sizeof(iwe));
		iwe.cmd = IWEVGENIE;
		iwe.u.data.length = end - pos;
		*current_ev = iwe_stream_add_point(info, *current_ev,
						   end_buf, &iwe, pos);
	}
}


static char *
ieee80211_sta_scan_result(struct ieee80211_local *local,
			  struct iw_request_info *info,
			  struct ieee80211_sta_bss *bss,
			  char *current_ev, char *end_buf)
{
	struct iw_event iwe;
	char *buf;

	if (time_after(jiffies,
		       bss->last_update + IEEE80211_SCAN_RESULT_EXPIRE))
		return current_ev;

	memset(&iwe, 0, sizeof(iwe));
	iwe.cmd = SIOCGIWAP;
	iwe.u.ap_addr.sa_family = ARPHRD_ETHER;
	memcpy(iwe.u.ap_addr.sa_data, bss->bssid, ETH_ALEN);
	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
					  IW_EV_ADDR_LEN);

	memset(&iwe, 0, sizeof(iwe));
	iwe.cmd = SIOCGIWESSID;
	if (bss_mesh_cfg(bss)) {
		iwe.u.data.length = bss_mesh_id_len(bss);
		iwe.u.data.flags = 1;
		current_ev = iwe_stream_add_point(info, current_ev, end_buf,
						  &iwe, bss_mesh_id(bss));
	} else {
		iwe.u.data.length = bss->ssid_len;
		iwe.u.data.flags = 1;
		current_ev = iwe_stream_add_point(info, current_ev, end_buf,
						  &iwe, bss->ssid);
	}

	if (bss->capability & (WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS)
	    || bss_mesh_cfg(bss)) {
		memset(&iwe, 0, sizeof(iwe));
		iwe.cmd = SIOCGIWMODE;
		if (bss_mesh_cfg(bss))
			iwe.u.mode = IW_MODE_MESH;
		else if (bss->capability & WLAN_CAPABILITY_ESS)
			iwe.u.mode = IW_MODE_MASTER;
		else
			iwe.u.mode = IW_MODE_ADHOC;
		current_ev = iwe_stream_add_event(info, current_ev, end_buf,
						  &iwe, IW_EV_UINT_LEN);
	}

	memset(&iwe, 0, sizeof(iwe));
	iwe.cmd = SIOCGIWFREQ;
	iwe.u.freq.m = ieee80211_frequency_to_channel(bss->freq);
	iwe.u.freq.e = 0;
	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
					  IW_EV_FREQ_LEN);

	memset(&iwe, 0, sizeof(iwe));
	iwe.cmd = SIOCGIWFREQ;
	iwe.u.freq.m = bss->freq;
	iwe.u.freq.e = 6;
	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
					  IW_EV_FREQ_LEN);
	memset(&iwe, 0, sizeof(iwe));
	iwe.cmd = IWEVQUAL;
	iwe.u.qual.qual = bss->qual;
	iwe.u.qual.level = bss->signal;
	iwe.u.qual.noise = bss->noise;
	iwe.u.qual.updated = local->wstats_flags;
	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
					  IW_EV_QUAL_LEN);

	memset(&iwe, 0, sizeof(iwe));
	iwe.cmd = SIOCGIWENCODE;
	if (bss->capability & WLAN_CAPABILITY_PRIVACY)
		iwe.u.data.flags = IW_ENCODE_ENABLED | IW_ENCODE_NOKEY;
	else
		iwe.u.data.flags = IW_ENCODE_DISABLED;
	iwe.u.data.length = 0;
	current_ev = iwe_stream_add_point(info, current_ev, end_buf,
					  &iwe, "");

	ieee80211_sta_add_scan_ies(info, bss, &current_ev, end_buf);

	if (bss->supp_rates_len > 0) {
		/* display all supported rates in readable format */
		char *p = current_ev + iwe_stream_lcp_len(info);
		int i;

		memset(&iwe, 0, sizeof(iwe));
		iwe.cmd = SIOCGIWRATE;
		/* Those two flags are ignored... */
		iwe.u.bitrate.fixed = iwe.u.bitrate.disabled = 0;

		for (i = 0; i < bss->supp_rates_len; i++) {
			iwe.u.bitrate.value = ((bss->supp_rates[i] &
							0x7f) * 500000);
			p = iwe_stream_add_value(info, current_ev, p,
					end_buf, &iwe, IW_EV_PARAM_LEN);
		}
		current_ev = p;
	}

	buf = kmalloc(30, GFP_ATOMIC);
	if (buf) {
		memset(&iwe, 0, sizeof(iwe));
		iwe.cmd = IWEVCUSTOM;
		sprintf(buf, "tsf=%016llx", (unsigned long long)(bss->timestamp));
		iwe.u.data.length = strlen(buf);
		current_ev = iwe_stream_add_point(info, current_ev, end_buf,
						  &iwe, buf);
		memset(&iwe, 0, sizeof(iwe));
		iwe.cmd = IWEVCUSTOM;
		sprintf(buf, " Last beacon: %dms ago",
			jiffies_to_msecs(jiffies - bss->last_update));
		iwe.u.data.length = strlen(buf);
		current_ev = iwe_stream_add_point(info, current_ev,
						  end_buf, &iwe, buf);
		kfree(buf);
	}

	if (bss_mesh_cfg(bss)) {
		u8 *cfg = bss_mesh_cfg(bss);
		buf = kmalloc(50, GFP_ATOMIC);
		if (buf) {
			memset(&iwe, 0, sizeof(iwe));
			iwe.cmd = IWEVCUSTOM;
			sprintf(buf, "Mesh network (version %d)", cfg[0]);
			iwe.u.data.length = strlen(buf);
			current_ev = iwe_stream_add_point(info, current_ev,
							  end_buf,
							  &iwe, buf);
			sprintf(buf, "Path Selection Protocol ID: "
				"0x%02X%02X%02X%02X", cfg[1], cfg[2], cfg[3],
							cfg[4]);
			iwe.u.data.length = strlen(buf);
			current_ev = iwe_stream_add_point(info, current_ev,
							  end_buf,
							  &iwe, buf);
			sprintf(buf, "Path Selection Metric ID: "
				"0x%02X%02X%02X%02X", cfg[5], cfg[6], cfg[7],
							cfg[8]);
			iwe.u.data.length = strlen(buf);
			current_ev = iwe_stream_add_point(info, current_ev,
							  end_buf,
							  &iwe, buf);
			sprintf(buf, "Congestion Control Mode ID: "
				"0x%02X%02X%02X%02X", cfg[9], cfg[10],
							cfg[11], cfg[12]);
			iwe.u.data.length = strlen(buf);
			current_ev = iwe_stream_add_point(info, current_ev,
							  end_buf,
							  &iwe, buf);
			sprintf(buf, "Channel Precedence: "
				"0x%02X%02X%02X%02X", cfg[13], cfg[14],
							cfg[15], cfg[16]);
			iwe.u.data.length = strlen(buf);
			current_ev = iwe_stream_add_point(info, current_ev,
							  end_buf,
							  &iwe, buf);
			kfree(buf);
		}
	}

	return current_ev;
}


int ieee80211_sta_scan_results(struct ieee80211_local *local,
			       struct iw_request_info *info,
			       char *buf, size_t len)
{
	char *current_ev = buf;
	char *end_buf = buf + len;
	struct ieee80211_sta_bss *bss;

	spin_lock_bh(&local->sta_bss_lock);
	list_for_each_entry(bss, &local->sta_bss_list, list) {
		if (buf + len - current_ev <= IW_EV_ADDR_LEN) {
			spin_unlock_bh(&local->sta_bss_lock);
			return -E2BIG;
		}
		current_ev = ieee80211_sta_scan_result(local, info, bss,
						       current_ev, end_buf);
	}
	spin_unlock_bh(&local->sta_bss_lock);
	return current_ev - buf;
}