mac80211: add direct probe before association

This patch adds a direct probe request as first step in the association
flow if data we have is not up to date. Motivation of this step is to make
sure that the bss information we have is correct, since last scan could
have been done a while ago, and beacons do not fully answer this need as
there are potential differences between them and probe responses (e.g.
WMM parameter element)

Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/ieee80211_i.h

@@ -100,7 +100,7 @@ struct ieee80211_sta_bss {
 	u64 timestamp;
 	int beacon_int;
 
-	bool probe_resp;
+	unsigned long last_probe_resp;
 	unsigned long last_update;
 
 	/* during assocation, we save an ERP value from a probe response so
@@ -294,12 +294,14 @@ struct mesh_config {
 #define IEEE80211_STA_PRIVACY_INVOKED	BIT(13)
 /* flags for  MLME request*/
 #define IEEE80211_STA_REQ_SCAN 0
-#define IEEE80211_STA_REQ_AUTH 1
-#define IEEE80211_STA_REQ_RUN  2
+#define IEEE80211_STA_REQ_DIRECT_PROBE 1
+#define IEEE80211_STA_REQ_AUTH 2
+#define IEEE80211_STA_REQ_RUN  3
 
 /* flags used for setting mlme state */
 enum ieee80211_sta_mlme_state {
 	IEEE80211_STA_MLME_DISABLED,
+	IEEE80211_STA_MLME_DIRECT_PROBE,
 	IEEE80211_STA_MLME_AUTHENTICATE,
 	IEEE80211_STA_MLME_ASSOCIATE,
 	IEEE80211_STA_MLME_ASSOCIATED,
@@ -362,6 +364,7 @@ struct ieee80211_if_sta {
 	struct sk_buff_head skb_queue;
 
 	int assoc_scan_tries; /* number of scans done pre-association */
+	int direct_probe_tries; /* retries for direct probes */
 	int auth_tries; /* retries for auth req */
 	int assoc_tries; /* retries for assoc req */
 

net/mac80211/mlme.c

@@ -595,8 +595,10 @@ static void ieee80211_set_associated(struct ieee80211_sub_if_data *sdata,
 static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 				   struct ieee80211_if_sta *ifsta, int deauth)
 {
-	if (deauth)
+	if (deauth) {
+		ifsta->direct_probe_tries = 0;
 		ifsta->auth_tries = 0;
+	}
 	ifsta->assoc_scan_tries = 0;
 	ifsta->assoc_tries = 0;
 	ieee80211_set_associated(sdata, ifsta, 0);
@@ -654,6 +656,36 @@ static void ieee80211_send_auth(struct ieee80211_sub_if_data *sdata,
 	ieee80211_sta_tx(sdata, skb, encrypt);
 }
 
+static void ieee80211_direct_probe(struct ieee80211_sub_if_data *sdata,
+				   struct ieee80211_if_sta *ifsta)
+{
+	DECLARE_MAC_BUF(mac);
+
+	ifsta->direct_probe_tries++;
+	if (ifsta->direct_probe_tries > IEEE80211_AUTH_MAX_TRIES) {
+		printk(KERN_DEBUG "%s: direct probe to AP %s timed out\n",
+		       sdata->dev->name, print_mac(mac, ifsta->bssid));
+		ifsta->state = IEEE80211_STA_MLME_DISABLED;
+		return;
+	}
+
+	printk(KERN_DEBUG "%s: direct probe to AP %s try %d\n",
+			sdata->dev->name, print_mac(mac, ifsta->bssid),
+			ifsta->direct_probe_tries);
+
+	ifsta->state = IEEE80211_STA_MLME_DIRECT_PROBE;
+
+	set_bit(IEEE80211_STA_REQ_DIRECT_PROBE, &ifsta->request);
+
+	/* Direct probe is sent to broadcast address as some APs
+	 * will not answer to direct packet in unassociated state.
+	 */
+	ieee80211_send_probe_req(sdata, NULL,
+				 ifsta->ssid, ifsta->ssid_len);
+
+	mod_timer(&ifsta->timer, jiffies + IEEE80211_AUTH_TIMEOUT);
+}
+
 
 static void ieee80211_authenticate(struct ieee80211_sub_if_data *sdata,
 				   struct ieee80211_if_sta *ifsta)
@@ -1947,7 +1979,7 @@ static void ieee80211_rx_mgmt_deauth(struct ieee80211_sub_if_data *sdata,
 	if (ifsta->state == IEEE80211_STA_MLME_AUTHENTICATE ||
 	    ifsta->state == IEEE80211_STA_MLME_ASSOCIATE ||
 	    ifsta->state == IEEE80211_STA_MLME_ASSOCIATED) {
-		ifsta->state = IEEE80211_STA_MLME_AUTHENTICATE;
+		ifsta->state = IEEE80211_STA_MLME_DIRECT_PROBE;
 		mod_timer(&ifsta->timer, jiffies +
 				      IEEE80211_RETRY_AUTH_INTERVAL);
 	}
@@ -2540,8 +2572,7 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 				  struct ieee80211_mgmt *mgmt,
 				  size_t len,
 				  struct ieee80211_rx_status *rx_status,
-				  struct ieee802_11_elems *elems,
-				  int beacon)
+				  struct ieee802_11_elems *elems)
 {
 	struct ieee80211_local *local = sdata->local;
 	int freq, clen;
@@ -2549,6 +2580,7 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 	struct sta_info *sta;
 	u64 beacon_timestamp, rx_timestamp;
 	struct ieee80211_channel *channel;
+	bool beacon = ieee80211_is_beacon(mgmt->frame_control);
 	DECLARE_MAC_BUF(mac);
 	DECLARE_MAC_BUF(mac2);
 
@@ -2705,15 +2737,14 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 	bss->signal = rx_status->signal;
 	bss->noise = rx_status->noise;
 	bss->qual = rx_status->qual;
-	if (!beacon && !bss->probe_resp)
-		bss->probe_resp = true;
-
+	if (!beacon)
+		bss->last_probe_resp = jiffies;
 	/*
 	 * In STA mode, the remaining parameters should not be overridden
 	 * by beacons because they're not necessarily accurate there.
 	 */
 	if (sdata->vif.type != IEEE80211_IF_TYPE_IBSS &&
-	    bss->probe_resp && beacon) {
+	    bss->last_probe_resp && beacon) {
 		ieee80211_rx_bss_put(local, bss);
 		return;
 	}
@@ -2868,6 +2899,7 @@ static void ieee80211_rx_mgmt_probe_resp(struct ieee80211_sub_if_data *sdata,
 {
 	size_t baselen;
 	struct ieee802_11_elems elems;
+	struct ieee80211_if_sta *ifsta = &sdata->u.sta;
 
 	if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
 		return; /* ignore ProbeResp to foreign address */
@@ -2879,7 +2911,15 @@ static void ieee80211_rx_mgmt_probe_resp(struct ieee80211_sub_if_data *sdata,
 	ieee802_11_parse_elems(mgmt->u.probe_resp.variable, len - baselen,
 				&elems);
 
-	ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems, 0);
+	ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems);
+
+	/* direct probe may be part of the association flow */
+	if (test_and_clear_bit(IEEE80211_STA_REQ_DIRECT_PROBE,
+							&ifsta->request)) {
+		printk(KERN_DEBUG "%s direct probe responded\n",
+		       sdata->dev->name);
+		ieee80211_authenticate(sdata, ifsta);
+	}
 }
 
 
@@ -2902,7 +2942,7 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 
 	ieee802_11_parse_elems(mgmt->u.beacon.variable, len - baselen, &elems);
 
-	ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems, 1);
+	ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems);
 
 	if (sdata->vif.type != IEEE80211_IF_TYPE_STA)
 		return;
@@ -3329,7 +3369,8 @@ void ieee80211_sta_work(struct work_struct *work)
 		mesh_path_start_discovery(sdata);
 #endif
 
-	if (ifsta->state != IEEE80211_STA_MLME_AUTHENTICATE &&
+	if (ifsta->state != IEEE80211_STA_MLME_DIRECT_PROBE &&
+	    ifsta->state != IEEE80211_STA_MLME_AUTHENTICATE &&
 	    ifsta->state != IEEE80211_STA_MLME_ASSOCIATE &&
 	    test_and_clear_bit(IEEE80211_STA_REQ_SCAN, &ifsta->request)) {
 		if (ifsta->scan_ssid_len)
@@ -3349,6 +3390,9 @@ void ieee80211_sta_work(struct work_struct *work)
 	switch (ifsta->state) {
 	case IEEE80211_STA_MLME_DISABLED:
 		break;
+	case IEEE80211_STA_MLME_DIRECT_PROBE:
+		ieee80211_direct_probe(sdata, ifsta);
+		break;
 	case IEEE80211_STA_MLME_AUTHENTICATE:
 		ieee80211_authenticate(sdata, ifsta);
 		break;
@@ -3408,6 +3452,7 @@ static void ieee80211_sta_reset_auth(struct ieee80211_sub_if_data *sdata,
 	ifsta->auth_transaction = -1;
 	ifsta->flags &= ~IEEE80211_STA_ASSOCIATED;
 	ifsta->assoc_scan_tries = 0;
+	ifsta->direct_probe_tries = 0;
 	ifsta->auth_tries = 0;
 	ifsta->assoc_tries = 0;
 	netif_carrier_off(sdata->dev);
@@ -3509,8 +3554,18 @@ static int ieee80211_sta_config_auth(struct ieee80211_sub_if_data *sdata,
 					       selected->ssid_len);
 		ieee80211_sta_set_bssid(sdata, selected->bssid);
 		ieee80211_sta_def_wmm_params(sdata, selected, 0);
+
+		/* Send out direct probe if no probe resp was received or
+		 * the one we have is outdated
+		 */
+		if (!selected->last_probe_resp ||
+		    time_after(jiffies, selected->last_probe_resp
+					+ IEEE80211_SCAN_RESULT_EXPIRE))
+			ifsta->state = IEEE80211_STA_MLME_DIRECT_PROBE;
+		else
+			ifsta->state = IEEE80211_STA_MLME_AUTHENTICATE;
+
 		ieee80211_rx_bss_put(local, selected);
-		ifsta->state = IEEE80211_STA_MLME_AUTHENTICATE;
 		ieee80211_sta_reset_auth(sdata, ifsta);
 		return 0;
 	} else {