nl80211: Filter out duplicated BSS table entries from scan results

cfg80211 maintains separate BSS table entries for APs if the same
BSSID,SSID pair is seen on multiple channels. wpa_supplicant does
not use frequency as a separate key in the BSS table, so filter out
duplicated entries. Prefer associated BSS entry in such a case in
order to get the correct frequency into the BSS table.

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 8a4b9ad1f33296608e49f92b88c8bce0b571afc8..b4f01faf302df50e2047def0b0b2275ae6f14573 100644 (file)
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -2415,6 +2415,7 @@ static int bss_info_handler(struct nl_msg *msg, void *arg)
        const u8 *ie, *beacon_ie;
        size_t ie_len, beacon_ie_len;
        u8 *pos;
+       size_t i;
 
        nla_parse(tb, NL80211_ATTR_MAX, genlmsg_attrdata(gnlh, 0),
                  genlmsg_attrlen(gnlh, 0), NULL);
@@ -2506,6 +2507,38 @@ static int bss_info_handler(struct nl_msg *msg, void *arg)
                }
        }
 
+       /*
+        * cfg80211 maintains separate BSS table entries for APs if the same
+        * BSSID,SSID pair is seen on multiple channels. wpa_supplicant does
+        * not use frequency as a separate key in the BSS table, so filter out
+        * duplicated entries. Prefer associated BSS entry in such a case in
+        * order to get the correct frequency into the BSS table.
+        */
+       for (i = 0; i < res->num; i++) {
+               const u8 *s1, *s2;
+               if (os_memcmp(res->res[i]->bssid, r->bssid, ETH_ALEN) != 0)
+                       continue;
+
+               s1 = nl80211_get_ie((u8 *) (res->res[i] + 1),
+                                   res->res[i]->ie_len, WLAN_EID_SSID);
+               s2 = nl80211_get_ie((u8 *) (r + 1), r->ie_len, WLAN_EID_SSID);
+               if (s1 == NULL || s2 == NULL || s1[1] != s2[1] ||
+                   os_memcmp(s1, s2, 2 + s1[1]) != 0)
+                       continue;
+
+               /* Same BSSID,SSID was already included in scan results */
+               wpa_printf(MSG_DEBUG, "nl80211: Remove duplicated scan result "
+                          "for " MACSTR, MAC2STR(r->bssid));
+
+               if ((r->flags & WPA_SCAN_ASSOCIATED) &&
+                   !(res->res[i]->flags & WPA_SCAN_ASSOCIATED)) {
+                       os_free(res->res[i]);
+                       res->res[i] = r;
+               } else
+                       os_free(r);
+               return NL_SKIP;
+       }
+
        tmp = os_realloc(res->res,
                         (res->num + 1) * sizeof(struct wpa_scan_res *));
        if (tmp == NULL) {