Ask driver to report only new scan results if requested

If the BSS table within wpa_supplicant is flushed, request the driver to
flush its own scan result table during the next scan. This can avoid
unexpected old BSS entries showing up after BSS_FLUSH or FLUSH command
in cases where the driver may maintain its internal cache of scan
results (e.g., cfg80211 BSS table persists at least for 15 seconds).

In addition to doing this automatically on BSS_FLUSH/FLUSH, a new SCAN
command argument, only_new=1, can be used to request a manual scan
request to do same. Though, it should be noted that this maintains the
BSS table within wpa_supplicant. BSS_FLUSH followed by SCAN command can
be used to clear all BSS entries from both the driver and
wpa_supplicant.

Signed-hostap: Jouni Malinen <j@w1.fi>

diff --git a/src/drivers/driver.h b/src/drivers/driver.h
index b4442becbb5a4c86d190b01a1fee6d463c493f58..4e5ab34b4e067bcc7038a87855b079e0a32333bd 100644 (file)
--- a/src/drivers/driver.h
+++ b/src/drivers/driver.h
@@ -340,6 +340,15 @@ struct wpa_driver_scan_params {
         * and not to transmit the frames at any of those rates.
         */
        u8 p2p_probe;
+
+       /**
+        * only_new_results - Request driver to report only new results
+        *
+        * This is used to request the driver to report only BSSes that have
+        * been detected after this scan request has been started, i.e., to
+        * flush old cached BSS entries.
+        */
+       int only_new_results;
 };
 
 /**

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 5aa692586d80384fb4deb9ef15816756aa9594f0..6c4c8167077cc8a87e88c8775c10b45647df16fc 100644 (file)
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -4679,6 +4679,12 @@ nl80211_scan_common(struct wpa_driver_nl80211_data *drv, u8 cmd,
        params->filter_ssids = NULL;
        drv->num_filter_ssids = params->num_filter_ssids;
 
+       if (params->only_new_results) {
+               wpa_printf(MSG_DEBUG, "nl80211: Add NL80211_SCAN_FLAG_FLUSH");
+               NLA_PUT_U32(msg, NL80211_ATTR_SCAN_FLAGS,
+                           NL80211_SCAN_FLAG_FLUSH);
+       }
+
        return msg;
 
 fail:

diff --git a/wpa_supplicant/bss.c b/wpa_supplicant/bss.c
index 033384ce1074e20e9de837a825073a5dbb39348d..9ea690330dccefce81629652b1170be6e1ede03e 100644 (file)
--- a/wpa_supplicant/bss.c
+++ b/wpa_supplicant/bss.c
@@ -820,6 +820,8 @@ void wpa_bss_flush(struct wpa_supplicant *wpa_s)
 {
        struct wpa_bss *bss, *n;
 
+       wpa_s->clear_driver_scan_cache = 1;
+
        if (wpa_s->bss.next == NULL)
                return; /* BSS table not yet initialized */
 

diff --git a/wpa_supplicant/ctrl_iface.c b/wpa_supplicant/ctrl_iface.c
index 7d7576f6e4c65f7110b0fd7c991a927372a11b3b..03b5e17241d1187c4cd43883d0421c770af9506d 100644 (file)
--- a/wpa_supplicant/ctrl_iface.c
+++ b/wpa_supplicant/ctrl_iface.c
@@ -5278,6 +5278,7 @@ static void wpas_ctrl_scan(struct wpa_supplicant *wpa_s, char *params,
 
        wpa_s->manual_scan_passive = 0;
        wpa_s->manual_scan_use_id = 0;
+       wpa_s->manual_scan_only_new = 0;
 
        if (params) {
                if (os_strncasecmp(params, "TYPE=ONLY", 9) == 0)
@@ -5296,6 +5297,10 @@ static void wpas_ctrl_scan(struct wpa_supplicant *wpa_s, char *params,
                pos = os_strstr(params, "use_id=");
                if (pos)
                        wpa_s->manual_scan_use_id = atoi(pos + 7);
+
+               pos = os_strstr(params, "only_new=1");
+               if (pos)
+                       wpa_s->manual_scan_only_new = 1;
        } else {
                os_free(wpa_s->manual_scan_freqs);
                wpa_s->manual_scan_freqs = NULL;

diff --git a/wpa_supplicant/scan.c b/wpa_supplicant/scan.c
index 34c430fabd3bb12f73442b31fab6a600efaadbe3..167ab9ddbe8168708cef011c85f7ceefa5d58ddf 100644 (file)
--- a/wpa_supplicant/scan.c
+++ b/wpa_supplicant/scan.c
@@ -155,6 +155,8 @@ int wpa_supplicant_trigger_scan(struct wpa_supplicant *wpa_s,
 
        wpa_supplicant_notify_scanning(wpa_s, 1);
 
+       if (wpa_s->clear_driver_scan_cache)
+               params->only_new_results = 1;
        ret = wpa_drv_scan(wpa_s, params);
        if (ret) {
                wpa_supplicant_notify_scanning(wpa_s, 0);
@@ -164,6 +166,7 @@ int wpa_supplicant_trigger_scan(struct wpa_supplicant *wpa_s,
                wpa_s->scan_runs++;
                wpa_s->normal_scans++;
                wpa_s->own_scan_requested = 1;
+               params->only_new_results = 0;
        }
 
        return ret;
@@ -727,6 +730,10 @@ ssid_list_set:
        wpa_supplicant_optimize_freqs(wpa_s, &params);
        extra_ie = wpa_supplicant_extra_ies(wpa_s);
 
+       if (wpa_s->last_scan_req == MANUAL_SCAN_REQ &&
+           wpa_s->manual_scan_only_new)
+               params.only_new_results = 1;
+
        if (wpa_s->last_scan_req == MANUAL_SCAN_REQ && params.freqs == NULL &&
            wpa_s->manual_scan_freqs) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Limit manual scan to specified channels");

diff --git a/wpa_supplicant/wpa_supplicant_i.h b/wpa_supplicant/wpa_supplicant_i.h
index 2e3f24494c15a3282cb9ddb141394eb2cafdbcf4..8563b18385debffa187579bab054077dbbd68770 100644 (file)
--- a/wpa_supplicant/wpa_supplicant_i.h
+++ b/wpa_supplicant/wpa_supplicant_i.h
@@ -484,9 +484,11 @@ struct wpa_supplicant {
        int *manual_scan_freqs;
        unsigned int manual_scan_passive:1;
        unsigned int manual_scan_use_id:1;
+       unsigned int manual_scan_only_new:1;
        unsigned int own_scan_requested:1;
        unsigned int own_scan_running:1;
        unsigned int external_scan_running:1;
+       unsigned int clear_driver_scan_cache:1;
        unsigned int manual_scan_id;
        int scan_interval; /* time in sec between scans to find suitable AP */
        int normal_scans; /* normal scans run before sched_scan */