WNM: Add support for SSID List element matching

This allows Probe Request frame processing to compare the configured
SSID to the SSID List element in addition to the SSID element.

Signed-hostap: Jouni Malinen <j@w1.fi>

src/ap/beacon.c

@@ -2,7 +2,7 @@
  * hostapd / IEEE 802.11 Management: Beacon and Probe Request/Response
  * Copyright (c) 2002-2004, Instant802 Networks, Inc.
  * Copyright (c) 2005-2006, Devicescape Software, Inc.
- * Copyright (c) 2008-2009, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2008-2012, Jouni Malinen <j@w1.fi>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -310,6 +310,46 @@ static u8 * hostapd_gen_probe_resp(struct hostapd_data *hapd,
 }
 
 
+enum ssid_match_result {
+	NO_SSID_MATCH,
+	EXACT_SSID_MATCH,
+	WILDCARD_SSID_MATCH
+};
+
+static enum ssid_match_result ssid_match(struct hostapd_data *hapd,
+					 const u8 *ssid, size_t ssid_len,
+					 const u8 *ssid_list,
+					 size_t ssid_list_len)
+{
+	const u8 *pos, *end;
+	int wildcard = 0;
+
+	if (ssid_len == 0)
+		wildcard = 1;
+	if (ssid_len == hapd->conf->ssid.ssid_len &&
+	    os_memcmp(ssid, hapd->conf->ssid.ssid, ssid_len) == 0)
+		return EXACT_SSID_MATCH;
+
+	if (ssid_list == NULL)
+		return wildcard ? WILDCARD_SSID_MATCH : NO_SSID_MATCH;
+
+	pos = ssid_list;
+	end = ssid_list + ssid_list_len;
+	while (pos + 1 <= end) {
+		if (pos + 2 + pos[1] > end)
+			break;
+		if (pos[1] == 0)
+			wildcard = 1;
+		if (pos[1] == hapd->conf->ssid.ssid_len &&
+		    os_memcmp(pos + 2, hapd->conf->ssid.ssid, pos[1]) == 0)
+			return EXACT_SSID_MATCH;
+		pos += 2 + pos[1];
+	}
+
+	return wildcard ? WILDCARD_SSID_MATCH : NO_SSID_MATCH;
+}
+
+
 void handle_probe_req(struct hostapd_data *hapd,
 		      const struct ieee80211_mgmt *mgmt, size_t len,
 		      int ssi_signal)
@@ -321,6 +361,7 @@ void handle_probe_req(struct hostapd_data *hapd,
 	struct sta_info *sta = NULL;
 	size_t i, resp_len;
 	int noack;
+	enum ssid_match_result res;
 
 	ie = mgmt->u.probe_req.variable;
 	if (len < IEEE80211_HDRLEN + sizeof(mgmt->u.probe_req))
@@ -376,7 +417,8 @@ void handle_probe_req(struct hostapd_data *hapd,
 	}
 #endif /* CONFIG_P2P */
 
-	if (hapd->conf->ignore_broadcast_ssid && elems.ssid_len == 0) {
+	if (hapd->conf->ignore_broadcast_ssid && elems.ssid_len == 0 &&
+	    elems.ssid_list_len == 0) {
 		wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR " for "
 			   "broadcast SSID ignored", MAC2STR(mgmt->sa));
 		return;
@@ -394,10 +436,9 @@ void handle_probe_req(struct hostapd_data *hapd,
 	}
 #endif /* CONFIG_P2P */
 
-	if (elems.ssid_len == 0 ||
-	    (elems.ssid_len == hapd->conf->ssid.ssid_len &&
-	     os_memcmp(elems.ssid, hapd->conf->ssid.ssid, elems.ssid_len) ==
-	     0)) {
+	res = ssid_match(hapd, elems.ssid, elems.ssid_len,
+			 elems.ssid_list, elems.ssid_list_len);
+	if (res != NO_SSID_MATCH) {
 		if (sta)
 			sta->ssid_probe = &hapd->conf->ssid;
 	} else {
@@ -406,9 +447,10 @@ void handle_probe_req(struct hostapd_data *hapd,
 			ieee802_11_print_ssid(ssid_txt, elems.ssid,
 					      elems.ssid_len);
 			wpa_printf(MSG_MSGDUMP, "Probe Request from " MACSTR
-				   " for foreign SSID '%s' (DA " MACSTR ")",
+				   " for foreign SSID '%s' (DA " MACSTR ")%s",
 				   MAC2STR(mgmt->sa), ssid_txt,
-				   MAC2STR(mgmt->da));
+				   MAC2STR(mgmt->da),
+				   elems.ssid_list ? " (SSID list)" : "");
 		}
 		return;
 	}
@@ -455,7 +497,8 @@ void handle_probe_req(struct hostapd_data *hapd,
 	 * If this is a broadcast probe request, apply no ack policy to avoid
 	 * excessive retries.
 	 */
-	noack = !!(elems.ssid_len == 0 && is_broadcast_ether_addr(mgmt->da));
+	noack = !!(res == WILDCARD_SSID_MATCH &&
+		   is_broadcast_ether_addr(mgmt->da));
 
 	if (hostapd_drv_send_mlme(hapd, resp, resp_len, noack) < 0)
 		perror("handle_probe_req: send");

src/ap/ieee802_11_shared.c

@@ -177,6 +177,10 @@ u8 * hostapd_eid_ext_capab(struct hostapd_data *hapd, u8 *eid)
 		len = 3;
 	if (len < 7 && hapd->conf->ssid.utf8_ssid)
 		len = 7;
+#ifdef CONFIG_WNM
+	if (len < 4)
+		len = 4;
+#endif /* CONFIG_WNM */
 	if (len == 0)
 		return eid;
 
@@ -193,6 +197,9 @@ u8 * hostapd_eid_ext_capab(struct hostapd_data *hapd, u8 *eid)
 	if (len < 4)
 		return pos;
 	*pos = 0x00;
+#ifdef CONFIG_WNM
+	*pos |= 0x02; /* Bit 25 - SSID List */
+#endif /* CONFIG_WNM */
 	if (hapd->conf->time_advertisement == 2)
 		*pos |= 0x08; /* Bit 27 - UTC TSF Offset */
 	if (hapd->conf->interworking)

src/common/ieee802_11_common.c

@@ -284,6 +284,10 @@ ParseRes ieee802_11_parse_elems(const u8 *start, size_t len,
 				break;
 			elems->bss_max_idle_period = pos;
 			break;
+		case WLAN_EID_SSID_LIST:
+			elems->ssid_list = pos;
+			elems->ssid_list_len = elen;
+			break;
 		default:
 			unknown++;
 			if (!show_errors)

src/common/ieee802_11_common.h

@@ -1,6 +1,6 @@
 /*
  * IEEE 802.11 Common routines
- * Copyright (c) 2002-2009, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2002-2012, Jouni Malinen <j@w1.fi>
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -43,6 +43,7 @@ struct ieee802_11_elems {
 	const u8 *hs20;
 	const u8 *ext_capab;
 	const u8 *bss_max_idle_period;
+	const u8 *ssid_list;
 
 	u8 ssid_len;
 	u8 supp_rates_len;
@@ -74,6 +75,7 @@ struct ieee802_11_elems {
 	u8 interworking_len;
 	u8 hs20_len;
 	u8 ext_capab_len;
+	u8 ssid_list_len;
 };
 
 typedef enum { ParseOK = 0, ParseUnknown = 1, ParseFailed = -1 } ParseRes;

src/common/ieee802_11_defs.h

@@ -232,6 +232,7 @@
 #define WLAN_EID_20_40_BSS_INTOLERANT 73
 #define WLAN_EID_OVERLAPPING_BSS_SCAN_PARAMS 74
 #define WLAN_EID_MMIE 76
+#define WLAN_EID_SSID_LIST 84
 #define WLAN_EID_BSS_MAX_IDLE_PERIOD 90
 #define WLAN_EID_TFS_REQ 91
 #define WLAN_EID_TFS_RESP 92