Add address masks to BSSID lists

In many applications it is useful not just to enumerate a group of well
known access points, but to use a address/mask notation to match an
entire set of addresses (ca:ff:ee:00:00:00/ff:ff:ff:00:00:00).

This change expands the data structures used by MAC lists to include a
mask indicating the significant (non-masked) portions of an address and
extends the list parser to recognize mask suffixes.

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

src/utils/common.c

@@ -36,6 +36,25 @@ int hex2byte(const char *hex)
 }
 
 
+static const char * hwaddr_parse(const char *txt, u8 *addr)
+{
+	size_t i;
+
+	for (i = 0; i < ETH_ALEN; i++) {
+		int a;
+
+		a = hex2byte(txt);
+		if (a < 0)
+			return NULL;
+		txt += 2;
+		addr[i] = a;
+		if (i < ETH_ALEN - 1 && *txt++ != ':')
+			return NULL;
+	}
+	return txt;
+}
+
+
 /**
  * hwaddr_aton - Convert ASCII string to MAC address (colon-delimited format)
  * @txt: MAC address as a string (e.g., "00:11:22:33:44:55")
@@ -44,25 +63,46 @@ int hex2byte(const char *hex)
  */
 int hwaddr_aton(const char *txt, u8 *addr)
 {
-	int i;
+	return hwaddr_parse(txt, addr) ? 0 : -1;
+}
 
-	for (i = 0; i < 6; i++) {
-		int a, b;
 
-		a = hex2num(*txt++);
+/**
-		if (a < 0)
+ * hwaddr_masked_aton - Convert ASCII string with optional mask to MAC address (colon-delimited format)
-			return -1;
+ * @txt: MAC address with optional mask as a string (e.g., "00:11:22:33:44:55/ff:ff:ff:ff:00:00")
-		b = hex2num(*txt++);
+ * @addr: Buffer for the MAC address (ETH_ALEN = 6 bytes)
-		if (b < 0)
+ * @mask: Buffer for the MAC address mask (ETH_ALEN = 6 bytes)
-			return -1;
+ * @maskable: Flag to indicate whether a mask is allowed
-		*addr++ = (a << 4) | b;
+ * Returns: 0 on success, -1 on failure (e.g., string not a MAC address)
-		if (i < 5 && *txt++ != ':')
+ */
+int hwaddr_masked_aton(const char *txt, u8 *addr, u8 *mask, u8 maskable)
+{
+	const char *r;
+
+	/* parse address part */
+	r = hwaddr_parse(txt, addr);
+	if (!r)
+		return -1;
+
+	/* check for optional mask */
+	if (*r == '\0' || isspace(*r)) {
+		/* no mask specified, assume default */
+		os_memset(mask, 0xff, ETH_ALEN);
+	} else if (maskable && *r == '/') {
+		/* mask specified and allowed */
+		r = hwaddr_parse(r + 1, mask);
+		/* parser error? */
+		if (!r)
 			return -1;
+	} else {
+		/* mask specified but not allowed or trailing garbage */
+		return -1;
 	}
 
 	return 0;
 }
 
+
 /**
  * hwaddr_compact_aton - Convert ASCII string to MAC address (no colon delimitors format)
  * @txt: MAC address as a string (e.g., "001122334455")
@@ -144,6 +184,30 @@ int hexstr2bin(const char *hex, u8 *buf, size_t len)
 }
 
 
+int hwaddr_mask_txt(char *buf, size_t len, const u8 *addr, const u8 *mask)
+{
+	size_t i;
+	int print_mask = 0;
+	int res;
+
+	for (i = 0; i < ETH_ALEN; i++) {
+		if (mask[i] != 0xff) {
+			print_mask = 1;
+			break;
+		}
+	}
+
+	if (print_mask)
+		res = os_snprintf(buf, len, MACSTR "/" MACSTR,
+				  MAC2STR(addr), MAC2STR(mask));
+	else
+		res = os_snprintf(buf, len, MACSTR, MAC2STR(addr));
+	if (os_snprintf_error(len, res))
+		return -1;
+	return res;
+}
+
+
 /**
  * inc_byte_array - Increment arbitrary length byte array by one
  * @counter: Pointer to byte array

src/utils/common.h

@@ -471,6 +471,7 @@ typedef u64 __bitwise le64;
 #endif /* __must_check */
 
 int hwaddr_aton(const char *txt, u8 *addr);
+int hwaddr_masked_aton(const char *txt, u8 *addr, u8 *mask, u8 maskable);
 int hwaddr_compact_aton(const char *txt, u8 *addr);
 int hwaddr_aton2(const char *txt, u8 *addr);
 int hex2byte(const char *hex);
@@ -482,6 +483,8 @@ int wpa_snprintf_hex(char *buf, size_t buf_size, const u8 *data, size_t len);
 int wpa_snprintf_hex_uppercase(char *buf, size_t buf_size, const u8 *data,
 			       size_t len);
 
+int hwaddr_mask_txt(char *buf, size_t len, const u8 *addr, const u8 *mask);
+
 #ifdef CONFIG_NATIVE_WINDOWS
 void wpa_unicode2ascii_inplace(TCHAR *str);
 TCHAR * wpa_strdup_tchar(const char *str);

wpa_supplicant/config.c

@@ -238,10 +238,10 @@ static char * wpa_config_write_int(const struct parse_data *data,
 static int wpa_config_parse_addr_list(const struct parse_data *data,
 				      int line, const char *value,
 				      u8 **list, size_t *num, char *name,
-				      u8 abort_on_error)
+				      u8 abort_on_error, u8 masked)
 {
 	const char *pos;
-	u8 *buf, *n, addr[ETH_ALEN];
+	u8 *buf, *n, addr[2 * ETH_ALEN];
 	size_t count;
 
 	buf = NULL;
@@ -252,7 +252,7 @@ static int wpa_config_parse_addr_list(const struct parse_data *data,
 		while (*pos == ' ')
 			pos++;
 
-		if (hwaddr_aton(pos, addr)) {
+		if (hwaddr_masked_aton(pos, addr, &addr[ETH_ALEN], masked)) {
 			if (abort_on_error || count == 0) {
 				wpa_printf(MSG_ERROR,
 					   "Line %d: Invalid %s address '%s'",
@@ -266,16 +266,20 @@ static int wpa_config_parse_addr_list(const struct parse_data *data,
 				   "Line %d: Ignore likely truncated %s address '%s'",
 				   line, name, pos);
 		} else {
-			n = os_realloc_array(buf, count + 1, ETH_ALEN);
+			n = os_realloc_array(buf, count + 1, 2 * ETH_ALEN);
 			if (n == NULL) {
 				os_free(buf);
 				return -1;
 			}
 			buf = n;
-			os_memmove(buf + ETH_ALEN, buf, count * ETH_ALEN);
+			os_memmove(buf + 2 * ETH_ALEN, buf,
-			os_memcpy(buf, addr, ETH_ALEN);
+				   count * 2 * ETH_ALEN);
+			os_memcpy(buf, addr, 2 * ETH_ALEN);
 			count++;
-			wpa_hexdump(MSG_MSGDUMP, name, addr, ETH_ALEN);
+			wpa_printf(MSG_MSGDUMP,
+				   "%s: addr=" MACSTR " mask=" MACSTR,
+				   name, MAC2STR(addr),
+				   MAC2STR(&addr[ETH_ALEN]));
 		}
 
 		pos = os_strchr(pos, ' ');
@@ -300,25 +304,26 @@ static char * wpa_config_write_addr_list(const struct parse_data *data,
 	if (list == NULL || num == 0)
 		return NULL;
 
-	value = os_malloc(20 * num);
+	value = os_malloc(2 * 20 * num);
 	if (value == NULL)
 		return NULL;
 	pos = value;
-	end = value + 20 * num;
+	end = value + 2 * 20 * num;
 
 	for (i = num; i > 0; i--) {
-		res = os_snprintf(pos, end - pos, MACSTR " ",
+		const u8 *a = list + (i - 1) * 2 * ETH_ALEN;
-				  MAC2STR(list + (i - 1) * ETH_ALEN));
+		const u8 *m = a + ETH_ALEN;
-		if (os_snprintf_error(end - pos, res)) {
+
+		if (i < num)
+			*pos++ = ' ';
+		res = hwaddr_mask_txt(pos, end - pos, a, m);
+		if (res < 0) {
 			os_free(value);
 			return NULL;
 		}
 		pos += res;
 	}
 
-	if (pos > value)
-		pos[-1] = '\0';
-
 	return value;
 }
 #endif /* NO_CONFIG_WRITE */
@@ -375,7 +380,7 @@ static int wpa_config_parse_bssid_blacklist(const struct parse_data *data,
 	return wpa_config_parse_addr_list(data, line, value,
 					  &ssid->bssid_blacklist,
 					  &ssid->num_bssid_blacklist,
-					  "bssid_blacklist", 1);
+					  "bssid_blacklist", 1, 1);
 }
 
 
@@ -397,7 +402,7 @@ static int wpa_config_parse_bssid_whitelist(const struct parse_data *data,
 	return wpa_config_parse_addr_list(data, line, value,
 					  &ssid->bssid_whitelist,
 					  &ssid->num_bssid_whitelist,
-					  "bssid_whitelist", 1);
+					  "bssid_whitelist", 1, 1);
 }
 
 
@@ -1588,7 +1593,7 @@ static int wpa_config_parse_p2p_client_list(const struct parse_data *data,
 	return wpa_config_parse_addr_list(data, line, value,
 					  &ssid->p2p_client_list,
 					  &ssid->num_p2p_clients,
-					  "p2p_client_list", 0);
+					  "p2p_client_list", 0, 0);
 }
 
 
@@ -2101,6 +2106,8 @@ void wpa_config_free_ssid(struct wpa_ssid *ssid)
 	os_free(ssid->freq_list);
 	os_free(ssid->bgscan);
 	os_free(ssid->p2p_client_list);
+	os_free(ssid->bssid_blacklist);
+	os_free(ssid->bssid_whitelist);
 #ifdef CONFIG_HT_OVERRIDES
 	os_free(ssid->ht_mcs);
 #endif /* CONFIG_HT_OVERRIDES */

wpa_supplicant/events.c

@@ -698,14 +698,27 @@ static int bss_is_ess(struct wpa_bss *bss)
 }
 
 
+static int match_mac_mask(const u8 *addr_a, const u8 *addr_b, const u8 *mask)
+{
+	size_t i;
+
+	for (i = 0; i < ETH_ALEN; i++) {
+		if ((addr_a[i] & mask[i]) != (addr_b[i] & mask[i]))
+			return 0;
+	}
+	return 1;
+}
+
+
 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);
+		const u8 *a = list + i * ETH_ALEN * 2;
+		const u8 *m = a + ETH_ALEN;
 
-		if (os_memcmp(a, addr, ETH_ALEN) == 0)
+		if (match_mac_mask(a, addr, m))
 			return 1;
 	}
 	return 0;

wpa_supplicant/p2p_supplicant.c

@@ -837,7 +837,7 @@ static void wpas_p2p_add_persistent_group_client(struct wpa_supplicant *wpa_s,
 		return;
 
 	for (i = 0; s->p2p_client_list && i < s->num_p2p_clients; i++) {
-		if (os_memcmp(s->p2p_client_list + i * ETH_ALEN, addr,
+		if (os_memcmp(s->p2p_client_list + i * 2 * ETH_ALEN, addr,
 			      ETH_ALEN) != 0)
 			continue;
 
@@ -845,32 +845,42 @@ static void wpas_p2p_add_persistent_group_client(struct wpa_supplicant *wpa_s,
 			return; /* already the most recent entry */
 
 		/* move the entry to mark it most recent */
-		os_memmove(s->p2p_client_list + i * ETH_ALEN,
+		os_memmove(s->p2p_client_list + i * 2 * ETH_ALEN,
-			   s->p2p_client_list + (i + 1) * ETH_ALEN,
+			   s->p2p_client_list + (i + 1) * 2 * ETH_ALEN,
-			   (s->num_p2p_clients - i - 1) * ETH_ALEN);
+			   (s->num_p2p_clients - i - 1) * 2 * ETH_ALEN);
 		os_memcpy(s->p2p_client_list +
-			  (s->num_p2p_clients - 1) * ETH_ALEN, addr, ETH_ALEN);
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN, addr,
+			  ETH_ALEN);
+		os_memset(s->p2p_client_list +
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN + ETH_ALEN,
+			  0xff, ETH_ALEN);
 		found = 1;
 		break;
 	}
 
 	if (!found && s->num_p2p_clients < P2P_MAX_STORED_CLIENTS) {
 		n = os_realloc_array(s->p2p_client_list,
-				     s->num_p2p_clients + 1, ETH_ALEN);
+				     s->num_p2p_clients + 1, 2 * ETH_ALEN);
 		if (n == NULL)
 			return;
-		os_memcpy(n + s->num_p2p_clients * ETH_ALEN, addr, ETH_ALEN);
+		os_memcpy(n + s->num_p2p_clients * 2 * ETH_ALEN, addr,
+			  ETH_ALEN);
+		os_memset(n + s->num_p2p_clients * 2 * ETH_ALEN + ETH_ALEN,
+			  0xff, ETH_ALEN);
 		s->p2p_client_list = n;
 		s->num_p2p_clients++;
 	} else if (!found && s->p2p_client_list) {
 		/* Not enough room for an additional entry - drop the oldest
 		 * entry */
 		os_memmove(s->p2p_client_list,
-			   s->p2p_client_list + ETH_ALEN,
+			   s->p2p_client_list + 2 * ETH_ALEN,
-			   (s->num_p2p_clients - 1) * ETH_ALEN);
+			   (s->num_p2p_clients - 1) * 2 * ETH_ALEN);
 		os_memcpy(s->p2p_client_list +
-			  (s->num_p2p_clients - 1) * ETH_ALEN,
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN,
 			  addr, ETH_ALEN);
+		os_memset(s->p2p_client_list +
+			  (s->num_p2p_clients - 1) * 2 * ETH_ALEN + ETH_ALEN,
+			  0xff, ETH_ALEN);
 	}
 
 	if (wpa_s->parent->conf->update_config &&
@@ -3348,7 +3358,7 @@ static void wpas_remove_persistent_peer(struct wpa_supplicant *wpa_s,
 		return;
 
 	for (i = 0; ssid->p2p_client_list && i < ssid->num_p2p_clients; i++) {
-		if (os_memcmp(ssid->p2p_client_list + i * ETH_ALEN, peer,
+		if (os_memcmp(ssid->p2p_client_list + i * 2 * ETH_ALEN, peer,
 			      ETH_ALEN) == 0)
 			break;
 	}
@@ -3368,9 +3378,9 @@ static void wpas_remove_persistent_peer(struct wpa_supplicant *wpa_s,
 		   "group %d client list%s",
 		   MAC2STR(peer), ssid->id,
 		   inv ? " due to invitation result" : "");
-	os_memmove(ssid->p2p_client_list + i * ETH_ALEN,
+	os_memmove(ssid->p2p_client_list + i * 2 * ETH_ALEN,
-		   ssid->p2p_client_list + (i + 1) * ETH_ALEN,
+		   ssid->p2p_client_list + (i + 1) * 2 * ETH_ALEN,
-		   (ssid->num_p2p_clients - i - 1) * ETH_ALEN);
+		   (ssid->num_p2p_clients - i - 1) * 2 * ETH_ALEN);
 	ssid->num_p2p_clients--;
 	if (wpa_s->parent->conf->update_config &&
 	    wpa_config_write(wpa_s->parent->confname, wpa_s->parent->conf))
@@ -7047,7 +7057,7 @@ struct wpa_ssid * wpas_p2p_get_persistent(struct wpa_supplicant *wpa_s,
 		if (s->mode != WPAS_MODE_P2P_GO || s->p2p_client_list == NULL)
 			continue;
 		for (i = 0; i < s->num_p2p_clients; i++) {
-			if (os_memcmp(s->p2p_client_list + i * ETH_ALEN,
+			if (os_memcmp(s->p2p_client_list + i * 2 * ETH_ALEN,
 				      addr, ETH_ALEN) == 0)
 				return s; /* peer is P2P client in persistent
 					   * group */

wpa_supplicant/wpa_supplicant.conf

@@ -1440,11 +1440,11 @@ network={
 }
 
 # Example configuration limiting AP selection to a specific set of APs;
-# any other AP will be ignored for this network entry.
+# any other AP not matching the masked address will be ignored.
 network={
 	ssid="example"
 	psk="very secret passphrase"
-	bssid_whitelist=02:55:ae:bc:de:f0 02:88:77:66:55:44
+	bssid_whitelist=02:55:ae:bc:00:00/ff:ff:ff:ff:00:00 00:00:77:66:55:44/00:00:ff:ff:ff:ff
 }
 
 # Example config file that will only scan on channel 36.