hostapd: Add some testing options

In order to test clients in scenarios where APs may (randomly)
drop certain management frames, introduce some testing options
into the hostapd configuration that can make it ignore certain
frames. For now, these are probe requests, authentication and
(re)association frames.

Signed-hostap: Johannes Berg <johannes.berg@intel.com>

hostapd/Makefile

@@ -824,6 +824,10 @@ LIBS += -lsqlite3
 LIBS_h += -lsqlite3
 endif
 
+ifdef CONFIG_TESTING_OPTIONS
+CFLAGS += -DCONFIG_TESTING_OPTIONS
+endif
+
 ALL=hostapd hostapd_cli
 
 all: verify_config $(ALL)

hostapd/config_file.c

@@ -2876,6 +2876,25 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 			bss->hs20_operating_class = oper_class;
 			bss->hs20_operating_class_len = oper_class_len;
 #endif /* CONFIG_HS20 */
+#ifdef CONFIG_TESTING_OPTIONS
+#define PARSE_TEST_PROBABILITY(_val)					\
+		} else if (os_strcmp(buf, #_val) == 0) {		\
+			char *end;					\
+									\
+			conf->_val = strtod(pos, &end);			\
+			if (*end || conf->_val < 0.0d ||		\
+			    conf->_val > 1.0d) {			\
+				wpa_printf(MSG_ERROR,			\
+					   "Line %d: Invalid value '%s'", \
+					   line, pos);			\
+				errors++;				\
+				return errors;				\
+			}
+		PARSE_TEST_PROBABILITY(ignore_probe_probability)
+		PARSE_TEST_PROBABILITY(ignore_auth_probability)
+		PARSE_TEST_PROBABILITY(ignore_assoc_probability)
+		PARSE_TEST_PROBABILITY(ignore_reassoc_probability)
+#endif /* CONFIG_TESTING_OPTIONS */
 		} else if (os_strcmp(buf, "vendor_elements") == 0) {
 			struct wpabuf *elems;
 			size_t len = os_strlen(pos);

hostapd/defconfig

@@ -267,3 +267,11 @@ CONFIG_IPV6=y
 
 # Enable SQLite database support in hlr_auc_gw, EAP-SIM DB, and eap_user_file
 #CONFIG_SQLITE=y
+
+# Testing options
+# This can be used to enable some testing options (see also the example
+# configuration file) that are really useful only for testing clients that
+# connect to this hostapd. These options allow, for example, to drop a
+# certain percentage of probe requests or auth/(re)assoc frames.
+#
+#CONFIG_TESTING_OPTIONS=y

hostapd/hostapd.conf

@@ -1521,6 +1521,25 @@ own_ip_addr=127.0.0.1
 # channels 36-48):
 #hs20_operating_class=5173
 
+##### TESTING OPTIONS #########################################################
+#
+# The options in this section are only available when the build configuration
+# option CONFIG_TESTING_OPTIONS is set while compiling hostapd. They allow
+# testing some scenarios that are otherwise difficult to reproduce.
+#
+# Ignore probe requests sent to hostapd with the given probability, must be a
+# floating point number in the range [0, 1).
+#ignore_probe_probability=0.0
+#
+# Ignore authentication frames with the given probability
+#ignore_auth_probability=0.0
+#
+# Ignore association requests with the given probability
+#ignore_assoc_probability=0.0
+#
+# Ignore reassociation requests with the given probability
+#ignore_reassoc_probability=0.0
+
 ##### Multiple BSSID support ##################################################
 #
 # Above configuration is using the default interface (wlan#, or multi-SSID VLAN

src/ap/ap_config.c

@@ -163,6 +163,13 @@ struct hostapd_config * hostapd_config_defaults(void)
 	conf->ap_table_max_size = 255;
 	conf->ap_table_expiration_time = 60;
 
+#ifdef CONFIG_TESTING_OPTIONS
+	conf->ignore_probe_probability = 0.0d;
+	conf->ignore_auth_probability = 0.0d;
+	conf->ignore_assoc_probability = 0.0d;
+	conf->ignore_reassoc_probability = 0.0d;
+#endif /* CONFIG_TESTING_OPTIONS */
+
 	return conf;
 }
 

src/ap/ap_config.h

@@ -520,6 +520,13 @@ struct hostapd_config {
 	u8 vht_oper_chwidth;
 	u8 vht_oper_centr_freq_seg0_idx;
 	u8 vht_oper_centr_freq_seg1_idx;
+
+#ifdef CONFIG_TESTING_OPTIONS
+	double ignore_probe_probability;
+	double ignore_auth_probability;
+	double ignore_assoc_probability;
+	double ignore_reassoc_probability;
+#endif /* CONFIG_TESTING_OPTIONS */
 };
 
 

src/ap/beacon.c

@@ -488,6 +488,16 @@ void handle_probe_req(struct hostapd_data *hapd,
 	/* TODO: verify that supp_rates contains at least one matching rate
 	 * with AP configuration */
 
+#ifdef CONFIG_TESTING_OPTIONS
+	if (hapd->iconf->ignore_probe_probability > 0.0d &&
+	    drand48() < hapd->iconf->ignore_probe_probability) {
+		wpa_printf(MSG_INFO,
+			   "TESTING: ignoring probe request from " MACSTR,
+			   MAC2STR(mgmt->sa));
+		return;
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
+
 	resp = hostapd_gen_probe_resp(hapd, sta, mgmt, elems.p2p != NULL,
 				      &resp_len);
 	if (resp == NULL)

src/ap/ieee802_11.c

@@ -557,6 +557,16 @@ static void handle_auth(struct hostapd_data *hapd,
 		return;
 	}
 
+#ifdef CONFIG_TESTING_OPTIONS
+	if (hapd->iconf->ignore_auth_probability > 0.0d &&
+	    drand48() < hapd->iconf->ignore_auth_probability) {
+		wpa_printf(MSG_INFO,
+			   "TESTING: ignoring auth frame from " MACSTR,
+			   MAC2STR(mgmt->sa));
+		return;
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
+
 	auth_alg = le_to_host16(mgmt->u.auth.auth_alg);
 	auth_transaction = le_to_host16(mgmt->u.auth.auth_transaction);
 	status_code = le_to_host16(mgmt->u.auth.status_code);
@@ -1226,6 +1236,26 @@ static void handle_assoc(struct hostapd_data *hapd,
 		return;
 	}
 
+#ifdef CONFIG_TESTING_OPTIONS
+	if (reassoc) {
+		if (hapd->iconf->ignore_reassoc_probability > 0.0d &&
+		    drand48() < hapd->iconf->ignore_reassoc_probability) {
+			wpa_printf(MSG_INFO,
+				   "TESTING: ignoring reassoc request from "
+				   MACSTR, MAC2STR(mgmt->sa));
+			return;
+		}
+	} else {
+		if (hapd->iconf->ignore_assoc_probability > 0.0d &&
+		    drand48() < hapd->iconf->ignore_assoc_probability) {
+			wpa_printf(MSG_INFO,
+				   "TESTING: ignoring assoc request from "
+				   MACSTR, MAC2STR(mgmt->sa));
+			return;
+		}
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
+
 	if (reassoc) {
 		capab_info = le_to_host16(mgmt->u.reassoc_req.capab_info);
 		listen_interval = le_to_host16(