From: Benjamin Berg <benjamin.berg@xxxxxxxxx>
When receiving a BTM request, wpa_s would try to fetch new results from
the driver, and, independently of that, would also process the latest
scan results that were partially updated by the previous fetch.
Simplify the logic by using wpa_supplicant_get_scan_results directly and
then processing the old scan data as usual. However, this data may be
outdated, so add a new heuristic to avoid roaming to a BSS if it is
either outdated or bad.
Doing this moves all scan data processing into wnm_scan_process.
Signed-off-by: Benjamin Berg <benjamin.berg@xxxxxxxxx>
---
wpa_supplicant/events.c | 2 +-
wpa_supplicant/wnm_sta.c | 146 ++++++++++++---------------------------
wpa_supplicant/wnm_sta.h | 2 +-
3 files changed, 45 insertions(+), 105 deletions(-)
diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c
index 9346a4f61..d61512124 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -2493,7 +2493,7 @@ static int _wpa_supplicant_event_scan_results(struct wpa_supplicant *wpa_s,
return 0;
}
- if (wnm_scan_process(wpa_s, 1) > 0)
+ if (wnm_scan_process(wpa_s, false) > 0)
goto scan_work_done;
if (sme_proc_obss_scan(wpa_s) > 0)
diff --git a/wpa_supplicant/wnm_sta.c b/wpa_supplicant/wnm_sta.c
index b340fae06..6f5f63a8d 100644
--- a/wpa_supplicant/wnm_sta.c
+++ b/wpa_supplicant/wnm_sta.c
@@ -1172,7 +1172,7 @@ static void wnm_bss_tm_connect(struct wpa_supplicant *wpa_s,
}
-int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail)
+int wnm_scan_process(struct wpa_supplicant *wpa_s, bool pre_scan_check)
{
struct wpa_bss *bss;
struct wpa_ssid *ssid = wpa_s->current_ssid;
@@ -1185,7 +1185,8 @@ int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail)
wpa_dbg(wpa_s, MSG_DEBUG,
"WNM: Process scan results for BSS Transition Management");
- if (os_reltime_before(&wpa_s->wnm_cand_valid_until,
+ if (!pre_scan_check &&
+ os_reltime_before(&wpa_s->wnm_cand_valid_until,
&wpa_s->scan_trigger_time)) {
wpa_printf(MSG_DEBUG, "WNM: Previously stored BSS transition candidate list is not valid anymore - drop it");
wnm_deallocate_memory(wpa_s);
@@ -1201,6 +1202,34 @@ int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail)
/* Compare the Neighbor Report and scan results */
bss = compare_scan_neighbor_results(wpa_s, 0, &reason);
+
+ /*
+ * If this is a pre-scan check, then returning 0 will trigger a scan
+ * and another call. In that case, reject "bad" candidates in the hope
+ * that a better candidate is found after scanning.
+ *
+ * Simple heuristic to check whether the selection is reasonable or a
+ * scan is a good idea. For that, we need to have found a candidate BSS
+ * (which might be the current one), it is up-to-date and we don't want
+ * to immediately roam back again.
+ */
+ if (pre_scan_check) {
+ struct os_reltime age;
+
+ if (!bss)
+ return 0;
+
+ os_reltime_age(&bss->last_update, &age);
+ if (age.sec >= 10)
+ return 0;
+
+ if (bss != wpa_s->current_bss &&
+ wpa_supplicant_need_to_roam_within_ess(wpa_s,
+ wpa_s->current_bss,
+ bss))
+ return 0;
+ }
+
if (!bss) {
wpa_printf(MSG_DEBUG, "WNM: No BSS transition candidate match found");
status = WNM_BSS_TM_REJECT_NO_SUITABLE_CANDIDATES;
@@ -1212,9 +1241,6 @@ int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail)
return 1;
send_bss_resp_fail:
- if (!reply_on_fail)
- return 0;
-
/* Send reject response for all the failures */
if (wpa_s->wnm_reply) {
@@ -1354,79 +1380,6 @@ static void wnm_set_scan_freqs(struct wpa_supplicant *wpa_s)
}
-static int wnm_fetch_scan_results(struct wpa_supplicant *wpa_s)
-{
- struct wpa_scan_results *scan_res;
- struct wpa_bss *bss;
- struct wpa_ssid *ssid = wpa_s->current_ssid;
- u8 i, found = 0;
- size_t j;
-
- wpa_dbg(wpa_s, MSG_DEBUG,
- "WNM: Fetch current scan results from the driver for checking transition candidates");
- scan_res = wpa_drv_get_scan_results2(wpa_s);
- if (!scan_res) {
- wpa_dbg(wpa_s, MSG_DEBUG, "WNM: Failed to get scan results");
- return 0;
- }
-
- if (scan_res->fetch_time.sec == 0)
- os_get_reltime(&scan_res->fetch_time);
-
- filter_scan_res(wpa_s, scan_res);
-
- for (i = 0; i < wpa_s->wnm_num_neighbor_report; i++) {
- struct neighbor_report *nei;
-
- nei = &wpa_s->wnm_neighbor_report_elements[i];
- if (nei->preference_present && nei->preference == 0)
- continue;
-
- for (j = 0; j < scan_res->num; j++) {
- struct wpa_scan_res *res;
- const u8 *ssid_ie;
-
- res = scan_res->res[j];
- if (!ether_addr_equal(nei->bssid, res->bssid) ||
- res->age > WNM_SCAN_RESULT_AGE * 1000)
- continue;
- bss = wpa_s->current_bss;
- ssid_ie = wpa_scan_get_ie(res, WLAN_EID_SSID);
- if (bss && ssid_ie && ssid_ie[1] &&
- (bss->ssid_len != ssid_ie[1] ||
- os_memcmp(bss->ssid, ssid_ie + 2,
- bss->ssid_len) != 0))
- continue; /* Skip entries for other ESSs */
-
- /* Potential candidate found */
- found = 1;
- scan_snr(res);
- scan_est_throughput(wpa_s, res);
- wpa_bss_update_scan_res(wpa_s, res,
- &scan_res->fetch_time);
- }
- }
-
- wpa_scan_results_free(scan_res);
- if (!found) {
- wpa_dbg(wpa_s, MSG_DEBUG,
- "WNM: No transition candidate matches existing scan results");
- return 0;
- }
-
- bss = compare_scan_neighbor_results(wpa_s, WNM_SCAN_RESULT_AGE, NULL);
- if (!bss) {
- wpa_dbg(wpa_s, MSG_DEBUG,
- "WNM: Comparison of scan results against transition candidates did not find matches");
- return 0;
- }
-
- /* Associate to the network */
- wnm_bss_tm_connect(wpa_s, bss, ssid, 0);
- return 1;
-}
-
-
static void ieee802_11_rx_bss_trans_mgmt_req(struct wpa_supplicant *wpa_s,
const u8 *pos, const u8 *end,
int reply)
@@ -1634,32 +1587,19 @@ static void ieee802_11_rx_bss_trans_mgmt_req(struct wpa_supplicant *wpa_s,
os_memcpy(wpa_s->wnm_cand_from_bss, wpa_s->bssid, ETH_ALEN);
/*
- * Fetch the latest scan results from the kernel and check for
- * candidates based on those results first. This can help in
- * finding more up-to-date information should the driver has
- * done some internal scanning operations after the last scan
- * result update in wpa_supplicant.
- */
- if (wnm_fetch_scan_results(wpa_s) > 0)
+ * Try fetching the latest scan results from the kernel.
+ * This can help in finding more up-to-date information should the
+ * driver have done some internal scanning operations after the last
+ * scan result update in wpa_supplicant.
+ *
+ * It is not a new scan, this does not update the last_scan timestamp
+ * nor will it expire old BSSs.
+ */
+ wpa_supplicant_update_scan_results(wpa_s);
+ if (wnm_scan_process(wpa_s, true) > 0)
return;
-
- /*
- * Try to use previously received scan results, if they are
- * recent enough to use for a connection.
- */
- if (wpa_s->last_scan_res_used > 0) {
- struct os_reltime now;
-
- os_get_reltime(&now);
- if (!os_reltime_expired(&now, &wpa_s->last_scan, 10)) {
- wpa_printf(MSG_DEBUG,
- "WNM: Try to use recent scan results");
- if (wnm_scan_process(wpa_s, 0) > 0)
- return;
- wpa_printf(MSG_DEBUG,
- "WNM: No match in previous scan results - try a new scan");
- }
- }
+ wpa_printf(MSG_DEBUG,
+ "WNM: No valid match in previous scan results - try a new scan");
wnm_set_scan_freqs(wpa_s);
if (wpa_s->wnm_num_neighbor_report == 1) {
diff --git a/wpa_supplicant/wnm_sta.h b/wpa_supplicant/wnm_sta.h
index 2a473db4e..2eaa2964f 100644
--- a/wpa_supplicant/wnm_sta.h
+++ b/wpa_supplicant/wnm_sta.h
@@ -75,7 +75,7 @@ bool wnm_is_bss_excluded(struct wpa_supplicant *wpa_s, struct wpa_bss *bss);
#ifdef CONFIG_WNM
-int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail);
+int wnm_scan_process(struct wpa_supplicant *wpa_s, bool pre_scan_check);
void wnm_clear_coloc_intf_reporting(struct wpa_supplicant *wpa_s);
#else /* CONFIG_WNM */
--
2.43.2
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