Add network specific BSSID black and white lists

This change adds the configuration options "bssid_whitelist" and
"bssid_blacklist" used to limit the AP selection of a network to a
specified (finite) set or discard certain APs.

This can be useful for environments where multiple networks operate
using the same SSID and roaming between those is not desired. It is also
useful to ignore a faulty or otherwise unwanted AP.

Signed-off-by: Stefan Tomanek <stefan.tomanek@wertarbyte.de>

wpa_supplicant/config.c

@@ -368,6 +368,50 @@ static char * wpa_config_write_bssid(const struct parse_data *data,
 #endif /* NO_CONFIG_WRITE */
 
 
+static int wpa_config_parse_bssid_blacklist(const struct parse_data *data,
+					    struct wpa_ssid *ssid, int line,
+					    const char *value)
+{
+	return wpa_config_parse_addr_list(data, line, value,
+					  &ssid->bssid_blacklist,
+					  &ssid->num_bssid_blacklist,
+					  "bssid_blacklist", 1);
+}
+
+
+#ifndef NO_CONFIG_WRITE
+static char * wpa_config_write_bssid_blacklist(const struct parse_data *data,
+					       struct wpa_ssid *ssid)
+{
+	return wpa_config_write_addr_list(data, ssid->bssid_blacklist,
+					  ssid->num_bssid_blacklist,
+					  "bssid_blacklist");
+}
+#endif /* NO_CONFIG_WRITE */
+
+
+static int wpa_config_parse_bssid_whitelist(const struct parse_data *data,
+					    struct wpa_ssid *ssid, int line,
+					    const char *value)
+{
+	return wpa_config_parse_addr_list(data, line, value,
+					  &ssid->bssid_whitelist,
+					  &ssid->num_bssid_whitelist,
+					  "bssid_whitelist", 1);
+}
+
+
+#ifndef NO_CONFIG_WRITE
+static char * wpa_config_write_bssid_whitelist(const struct parse_data *data,
+					       struct wpa_ssid *ssid)
+{
+	return wpa_config_write_addr_list(data, ssid->bssid_whitelist,
+					  ssid->num_bssid_whitelist,
+					  "bssid_whitelist");
+}
+#endif /* NO_CONFIG_WRITE */
+
+
 static int wpa_config_parse_psk(const struct parse_data *data,
 				struct wpa_ssid *ssid, int line,
 				const char *value)
@@ -1744,6 +1788,8 @@ static const struct parse_data ssid_fields[] = {
 	{ STR_RANGE(ssid, 0, MAX_SSID_LEN) },
 	{ INT_RANGE(scan_ssid, 0, 1) },
 	{ FUNC(bssid) },
+	{ FUNC(bssid_blacklist) },
+	{ FUNC(bssid_whitelist) },
 	{ FUNC_KEY(psk) },
 	{ FUNC(proto) },
 	{ FUNC(key_mgmt) },

wpa_supplicant/config_ssid.h

@@ -131,6 +131,18 @@ struct wpa_ssid {
 	 */
 	u8 bssid[ETH_ALEN];
 
+	/**
+	 * bssid_blacklist - List of inacceptable BSSIDs
+	 */
+	u8 *bssid_blacklist;
+	size_t num_bssid_blacklist;
+
+	/**
+	 * bssid_blacklist - List of acceptable BSSIDs
+	 */
+	u8 *bssid_whitelist;
+	size_t num_bssid_whitelist;
+
 	/**
 	 * bssid_set - Whether BSSID is configured for this network
 	 */

wpa_supplicant/events.c

@@ -698,6 +698,20 @@ static int bss_is_ess(struct wpa_bss *bss)
 }
 
 
+static int addr_in_list(const u8 *addr, const u8 *list, size_t num)
+{
+	size_t i;
+
+	for (i = 0; i < num; i++) {
+		const u8 *a = list + (i * ETH_ALEN);
+
+		if (os_memcmp(a, addr, ETH_ALEN) == 0)
+			return 1;
+	}
+	return 0;
+}
+
+
 static struct wpa_ssid * wpa_scan_res_match(struct wpa_supplicant *wpa_s,
 					    int i, struct wpa_bss *bss,
 					    struct wpa_ssid *group,
@@ -822,6 +836,24 @@ static struct wpa_ssid * wpa_scan_res_match(struct wpa_supplicant *wpa_s,
 			continue;
 		}
 
+		/* check blacklist */
+		if (ssid->num_bssid_blacklist &&
+		    addr_in_list(bss->bssid, ssid->bssid_blacklist,
+				 ssid->num_bssid_blacklist)) {
+			wpa_dbg(wpa_s, MSG_DEBUG,
+				"   skip - BSSID blacklisted");
+			continue;
+		}
+
+		/* if there is a whitelist, only accept those APs */
+		if (ssid->num_bssid_whitelist &&
+		    !addr_in_list(bss->bssid, ssid->bssid_whitelist,
+				  ssid->num_bssid_whitelist)) {
+			wpa_dbg(wpa_s, MSG_DEBUG,
+				"   skip - BSSID not in whitelist");
+			continue;
+		}
+
 		if (!wpa_supplicant_ssid_bss_match(wpa_s, ssid, bss))
 			continue;
 

wpa_supplicant/wpa_supplicant.conf

@@ -1431,6 +1431,21 @@ network={
 	key_mgmt=NONE
 }
 
+# Example configuration blacklisting two APs - these will be ignored
+# for this network.
+network={
+	ssid="example"
+	psk="very secret passphrase"
+	bssid_blacklist=02:11:22:33:44:55 02:22:aa:44:55:66
+}
+
+# Example configuration limiting AP selection to a specific set of APs;
+# any other AP will be ignored for this network entry.
+network={
+	ssid="example"
+	psk="very secret passphrase"
+	bssid_whitelist=02:55:ae:bc:de:f0 02:88:77:66:55:44
+}
 
 # Example config file that will only scan on channel 36.
 freq_list=5180