nl80211: Update drv->ssid on connect/associate event based on BSS data

On a connect nl80211 event, wpa_supplicant uses
wpa_driver_nl80211_get_ssid() to fetch the current associated SSID to
compare to existing configurations. However,
wpa_driver_nl80211_get_ssid() uses drv->ssid, which is a cached value.
It is set when we explicitly initial a connect request using
wpa_supplicant. If the association was initiated outside of
wpa_supplicant, we need another way to populate drv->ssid. This commit
sets drv->ssid based on cfg80211 BSS information on connect/associate
nl80211 events.

Signed-off-by: Ningyuan Wang <nywang@google.com>

src/drivers/driver_nl80211.c

@@ -1186,6 +1186,8 @@ struct nl80211_get_assoc_freq_arg {
 	unsigned int assoc_freq;
 	unsigned int ibss_freq;
 	u8 assoc_bssid[ETH_ALEN];
+	u8 assoc_ssid[SSID_MAX_LEN];
+	u8 assoc_ssid_len;
 };
 
 static int nl80211_get_assoc_freq_handler(struct nl_msg *msg, void *arg)
@@ -1196,6 +1198,7 @@ static int nl80211_get_assoc_freq_handler(struct nl_msg *msg, void *arg)
 	static struct nla_policy bss_policy[NL80211_BSS_MAX + 1] = {
 		[NL80211_BSS_BSSID] = { .type = NLA_UNSPEC },
 		[NL80211_BSS_FREQUENCY] = { .type = NLA_U32 },
+		[NL80211_BSS_INFORMATION_ELEMENTS] = { .type = NLA_UNSPEC },
 		[NL80211_BSS_STATUS] = { .type = NLA_U32 },
 	};
 	struct nl80211_get_assoc_freq_arg *ctx = arg;
@@ -1230,10 +1233,45 @@ static int nl80211_get_assoc_freq_handler(struct nl_msg *msg, void *arg)
 			   MACSTR, MAC2STR(ctx->assoc_bssid));
 	}
 
+	if (status == NL80211_BSS_STATUS_ASSOCIATED &&
+	    bss[NL80211_BSS_INFORMATION_ELEMENTS]) {
+		const u8 *ie, *ssid;
+		size_t ie_len;
+
+		ie = nla_data(bss[NL80211_BSS_INFORMATION_ELEMENTS]);
+		ie_len = nla_len(bss[NL80211_BSS_INFORMATION_ELEMENTS]);
+		ssid = get_ie(ie, ie_len, WLAN_EID_SSID);
+		if (ssid && ssid[1] > 0 && ssid[1] <= SSID_MAX_LEN) {
+			ctx->assoc_ssid_len = ssid[1];
+			os_memcpy(ctx->assoc_ssid, ssid + 2, ssid[1]);
+		}
+	}
+
 	return NL_SKIP;
 }
 
 
+int nl80211_get_assoc_ssid(struct wpa_driver_nl80211_data *drv, u8 *ssid)
+{
+	struct nl_msg *msg;
+	int ret;
+	struct nl80211_get_assoc_freq_arg arg;
+
+	msg = nl80211_drv_msg(drv, NLM_F_DUMP, NL80211_CMD_GET_SCAN);
+	os_memset(&arg, 0, sizeof(arg));
+	arg.drv = drv;
+	ret = send_and_recv_msgs(drv, msg, nl80211_get_assoc_freq_handler,
+				 &arg);
+	if (ret == 0) {
+		os_memcpy(ssid, arg.assoc_ssid, arg.assoc_ssid_len);
+		return arg.assoc_ssid_len;
+	}
+	wpa_printf(MSG_DEBUG, "nl80211: Scan result fetch failed: ret=%d (%s)",
+		   ret, strerror(-ret));
+	return ret;
+}
+
+
 unsigned int nl80211_get_assoc_freq(struct wpa_driver_nl80211_data *drv)
 {
 	struct nl_msg *msg;

src/drivers/driver_nl80211.h

@@ -228,6 +228,7 @@ int nl80211_create_iface(struct wpa_driver_nl80211_data *drv,
 			 void *arg, int use_existing);
 void nl80211_remove_iface(struct wpa_driver_nl80211_data *drv, int ifidx);
 unsigned int nl80211_get_assoc_freq(struct wpa_driver_nl80211_data *drv);
+int nl80211_get_assoc_ssid(struct wpa_driver_nl80211_data *drv, u8 *ssid);
 enum chan_width convert2width(int width);
 void nl80211_mark_disconnected(struct wpa_driver_nl80211_data *drv);
 struct i802_bss * get_bss_ifindex(struct wpa_driver_nl80211_data *drv,

src/drivers/driver_nl80211_event.c

@@ -206,6 +206,7 @@ static void mlme_event_assoc(struct wpa_driver_nl80211_data *drv,
 	const struct ieee80211_mgmt *mgmt;
 	union wpa_event_data event;
 	u16 status;
+	int ssid_len;
 
 	if (!(drv->capa.flags & WPA_DRIVER_FLAGS_SME) &&
 	    drv->force_connect_cmd) {
@@ -257,6 +258,16 @@ static void mlme_event_assoc(struct wpa_driver_nl80211_data *drv,
 
 	event.assoc_info.freq = drv->assoc_freq;
 
+	/* When this association was initiated outside of wpa_supplicant,
+	 * drv->ssid needs to be set here to satisfy later checking. */
+	ssid_len = nl80211_get_assoc_ssid(drv, drv->ssid);
+	if (ssid_len > 0) {
+		drv->ssid_len = ssid_len;
+		wpa_printf(MSG_DEBUG,
+			   "nl80211: Set drv->ssid based on scan res info to '%s'",
+			   wpa_ssid_txt(drv->ssid, drv->ssid_len));
+	}
+
 	nl80211_parse_wmm_params(wmm, &event.assoc_info.wmm_params);
 
 	wpa_supplicant_event(drv->ctx, EVENT_ASSOC, &event);
@@ -275,8 +286,9 @@ static void mlme_event_connect(struct wpa_driver_nl80211_data *drv,
 			       struct nlattr *subnet_status)
 {
 	union wpa_event_data event;
-	const u8 *ssid;
+	const u8 *ssid = NULL;
 	u16 status_code;
+	int ssid_len;
 
 	if (drv->capa.flags & WPA_DRIVER_FLAGS_SME) {
 		/*
@@ -347,6 +359,10 @@ static void mlme_event_connect(struct wpa_driver_nl80211_data *drv,
 			if (ssid && ssid[1] > 0 && ssid[1] <= 32) {
 				drv->ssid_len = ssid[1];
 				os_memcpy(drv->ssid, ssid + 2, ssid[1]);
+				wpa_printf(MSG_DEBUG,
+					   "nl80211: Set drv->ssid based on req_ie to '%s'",
+					   wpa_ssid_txt(drv->ssid,
+							drv->ssid_len));
 			}
 		}
 	}
@@ -357,6 +373,16 @@ static void mlme_event_connect(struct wpa_driver_nl80211_data *drv,
 
 	event.assoc_info.freq = nl80211_get_assoc_freq(drv);
 
+	if ((!ssid || ssid[1] == 0 || ssid[1] > 32) &&
+	    (ssid_len = nl80211_get_assoc_ssid(drv, drv->ssid)) > 0) {
+		/* When this connection was initiated outside of wpa_supplicant,
+		 * drv->ssid needs to be set here to satisfy later checking. */
+		drv->ssid_len = ssid_len;
+		wpa_printf(MSG_DEBUG,
+			   "nl80211: Set drv->ssid based on scan res info to '%s'",
+			   wpa_ssid_txt(drv->ssid, drv->ssid_len));
+	}
+
 	if (authorized && nla_get_u8(authorized)) {
 		event.assoc_info.authorized = 1;
 		wpa_printf(MSG_DEBUG, "nl80211: connection authorized");