[PATCH 1/2] Revert "STA OBSS: Add check for overlapping BSSs"

[Matthew Wang]

This reverts commit 3204795d7a43bcbda8b695dd96d11f3000de7340.

The commit adds an additional check that checks for overlapping BSSs in
addition to the existing 40MHz intolerance subfield checks. The commit
cites IEEE Std 802.11-2016 section 11.16.12, which defines the proper
behavior for a 20/40MHz HT STA and AP, but the spec actually doesn't say
anything about overlapping BSSs. Specifically, the spec states that the
only BSSs that belong in the Intolerant channel report are those that
satisfy trigger event A, defined as channels with BSSs that don't
contain the HT capabilities element (which wpa_supplicant already did
before). Note that we also include channels with BSSs that have the
40MHz intolerance bit set in the Intolerant channel report.

Signed-off-by: Matthew Wang <matthewmwang at chromium.org>
---
 wpa_supplicant/events.c |  2 +-
 wpa_supplicant/sme.c    | 42 +++++++++++++----------------------------
 wpa_supplicant/sme.h    |  6 ++----
 3 files changed, 16 insertions(+), 34 deletions(-)

diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c
index 5f5c50ba975..f55e1846e20 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -2177,7 +2177,7 @@ static int _wpa_supplicant_event_scan_results(struct wpa_supplicant *wpa_s,
 	if (wnm_scan_process(wpa_s, 1) > 0)
 		goto scan_work_done;
 
-	if (sme_proc_obss_scan(wpa_s, scan_res) > 0)
+	if (sme_proc_obss_scan(wpa_s) > 0)
 		goto scan_work_done;
 
 	if (own_request && data &&
diff --git a/wpa_supplicant/sme.c b/wpa_supplicant/sme.c
index f2c42ff354e..0dd3772f374 100644
--- a/wpa_supplicant/sme.c
+++ b/wpa_supplicant/sme.c
@@ -13,7 +13,6 @@
 #include "common/ieee802_11_defs.h"
 #include "common/ieee802_11_common.h"
 #include "common/ocv.h"
-#include "common/hw_features_common.h"
 #include "eapol_supp/eapol_supp_sm.h"
 #include "common/wpa_common.h"
 #include "common/sae.h"
@@ -2380,14 +2379,13 @@ static void sme_send_2040_bss_coex(struct wpa_supplicant *wpa_s,
 }
 
 
-int sme_proc_obss_scan(struct wpa_supplicant *wpa_s,
-		       struct wpa_scan_results *scan_res)
+int sme_proc_obss_scan(struct wpa_supplicant *wpa_s)
 {
+	struct wpa_bss *bss;
 	const u8 *ie;
+	u16 ht_cap;
 	u8 chan_list[P2P_MAX_CHANNELS], channel;
 	u8 num_channels = 0, num_intol = 0, i;
-	size_t j;
-	int pri_freq, sec_freq;
 
 	if (!wpa_s->sme.sched_obss_scan)
 		return 0;
@@ -2415,36 +2413,22 @@ int sme_proc_obss_scan(struct wpa_supplicant *wpa_s,
 
 	os_memset(chan_list, 0, sizeof(chan_list));
 
-	pri_freq = wpa_s->assoc_freq;
-
-	switch (wpa_s->sme.ht_sec_chan) {
-	case HT_SEC_CHAN_ABOVE:
-		sec_freq = pri_freq + 20;
-		break;
-	case HT_SEC_CHAN_BELOW:
-		sec_freq = pri_freq - 20;
-		break;
-	case HT_SEC_CHAN_UNKNOWN:
-	default:
-		wpa_msg(wpa_s, MSG_WARNING,
-			"Undefined secondary channel: drop OBSS scan results");
-		return 1;
-	}
-
-	for (j = 0; j < scan_res->num; j++) {
-		struct wpa_scan_res *bss = scan_res->res[j];
-		enum hostapd_hw_mode mode;
-		int res;
-
+	dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
 		/* Skip other band bss */
+		enum hostapd_hw_mode mode;
 		mode = ieee80211_freq_to_chan(bss->freq, &channel);
 		if (mode != HOSTAPD_MODE_IEEE80211G &&
 		    mode != HOSTAPD_MODE_IEEE80211B)
 			continue;
 
-		res = check_bss_coex_40mhz(bss, pri_freq, sec_freq);
-		if (res) {
-			if (res == 2)
+		ie = wpa_bss_get_ie(bss, WLAN_EID_HT_CAP);
+		ht_cap = (ie && (ie[1] == 26)) ? WPA_GET_LE16(ie + 2) : 0;
+		wpa_printf(MSG_DEBUG, "SME OBSS scan BSS " MACSTR
+			   " freq=%u chan=%u ht_cap=0x%x",
+			   MAC2STR(bss->bssid), bss->freq, channel, ht_cap);
+
+		if (!ht_cap || (ht_cap & HT_CAP_INFO_40MHZ_INTOLERANT)) {
+			if (ht_cap & HT_CAP_INFO_40MHZ_INTOLERANT)
 				num_intol++;
 
 			/* Check whether the channel is already considered */
diff --git a/wpa_supplicant/sme.h b/wpa_supplicant/sme.h
index ecbc16dacd9..c797d2e9e79 100644
--- a/wpa_supplicant/sme.h
+++ b/wpa_supplicant/sme.h
@@ -37,8 +37,7 @@ void sme_disassoc_while_authenticating(struct wpa_supplicant *wpa_s,
 void sme_clear_on_disassoc(struct wpa_supplicant *wpa_s);
 void sme_deinit(struct wpa_supplicant *wpa_s);
 
-int sme_proc_obss_scan(struct wpa_supplicant *wpa_s,
-		       struct wpa_scan_results *scan_res);
+int sme_proc_obss_scan(struct wpa_supplicant *wpa_s);
 void sme_sched_obss_scan(struct wpa_supplicant *wpa_s, int enable);
 void sme_external_auth_trigger(struct wpa_supplicant *wpa_s,
 			       union wpa_event_data *data);
@@ -113,8 +112,7 @@ static inline void sme_deinit(struct wpa_supplicant *wpa_s)
 {
 }
 
-static inline int sme_proc_obss_scan(struct wpa_supplicant *wpa_s,
-				     struct wpa_scan_results *scan_res)
+static inline int sme_proc_obss_scan(struct wpa_supplicant *wpa_s)
 {
 	return 0;
 }
-- 
2.31.0