hostapd: Accept interface names as a command line parameter

This introduces an optinal command line parameter '-i' to override the
value of the 'interface' attribute in hostapd.conf files. This change
enables the reuse of the configuration files for the concurrent
instances of hostapd. An ability to dynamically assign the interface
names simplifies the usages of hostapd service in the automated
emulations of the wireless environments.

Signed-off-by: Tim Kourt <tim.a.kourt@linux.intel.com>

hostapd/main.c

@@ -251,7 +251,7 @@ static int hostapd_driver_init(struct hostapd_iface *iface)
  * interfaces. No actiual driver operations are started.
  */
 static struct hostapd_iface *
-hostapd_interface_init(struct hapd_interfaces *interfaces,
+hostapd_interface_init(struct hapd_interfaces *interfaces, const char *if_name,
 		       const char *config_fname, int debug)
 {
 	struct hostapd_iface *iface;
@@ -261,6 +261,12 @@ hostapd_interface_init(struct hapd_interfaces *interfaces,
 	iface = hostapd_init(interfaces, config_fname);
 	if (!iface)
 		return NULL;
+
+	if (if_name) {
+		os_strlcpy(iface->conf->bss[0]->iface, if_name,
+			   sizeof(iface->conf->bss[0]->iface));
+	}
+
 	iface->interfaces = interfaces;
 
 	for (k = 0; k < debug; k++) {
@@ -270,7 +276,8 @@ hostapd_interface_init(struct hapd_interfaces *interfaces,
 
 	if (iface->conf->bss[0]->iface[0] == '\0' &&
 	    !hostapd_drv_none(iface->bss[0])) {
-		wpa_printf(MSG_ERROR, "Interface name not specified in %s",
+		wpa_printf(MSG_ERROR,
+			   "Interface name not specified in %s, nor by '-i' parameter",
 			   config_fname);
 		hostapd_interface_deinit_free(iface);
 		return NULL;
@@ -457,6 +464,7 @@ static void usage(void)
 		"usage: hostapd [-hdBKtv] [-P <PID file>] [-e <entropy file>] "
 		"\\\n"
 		"         [-g <global ctrl_iface>] [-G <group>]\\\n"
+		"         [-i <comma-separated list of interface names>]\\\n"
 		"         <configuration file(s)>\n"
 		"\n"
 		"options:\n"
@@ -475,6 +483,7 @@ static void usage(void)
 		"   -T = record to Linux tracing in addition to logging\n"
 		"        (records all messages regardless of debug verbosity)\n"
 #endif /* CONFIG_DEBUG_LINUX_TRACING */
+		"   -i   list of interface names to use\n"
 		"   -S   start all the interfaces synchronously\n"
 		"   -t   include timestamps in some debug messages\n"
 		"   -v   show hostapd version\n");
@@ -538,6 +547,43 @@ static int hostapd_get_ctrl_iface_group(struct hapd_interfaces *interfaces,
 }
 
 
+static int hostapd_get_interface_names(char ***if_names,
+				       size_t *if_names_size,
+				       char *optarg)
+{
+	char *if_name, *tmp, **nnames;
+	size_t i;
+
+	if (!optarg)
+		return -1;
+	if_name = strtok_r(optarg, ",", &tmp);
+
+	while (if_name) {
+		nnames = os_realloc_array(*if_names, 1 + *if_names_size,
+					  sizeof(char *));
+		if (!nnames)
+			goto fail;
+		*if_names = nnames;
+
+		(*if_names)[*if_names_size] = os_strdup(if_name);
+		if (!(*if_names)[*if_names_size])
+			goto fail;
+		(*if_names_size)++;
+		if_name = strtok_r(NULL, ",", &tmp);
+	}
+
+	return 0;
+
+fail:
+	for (i = 0; i < *if_names_size; i++)
+		os_free((*if_names)[i]);
+	os_free(*if_names);
+	*if_names = NULL;
+	*if_names_size = 0;
+	return -1;
+}
+
+
 #ifdef CONFIG_WPS
 static int gen_uuid(const char *txt_addr)
 {
@@ -596,6 +642,8 @@ int main(int argc, char *argv[])
 	int enable_trace_dbg = 0;
 #endif /* CONFIG_DEBUG_LINUX_TRACING */
 	int start_ifaces_in_sync = 0;
+	char **if_names = NULL;
+	size_t if_names_size = 0;
 
 	if (os_program_init())
 		return -1;
@@ -613,7 +661,7 @@ int main(int argc, char *argv[])
 	dl_list_init(&interfaces.global_ctrl_dst);
 
 	for (;;) {
-		c = getopt(argc, argv, "b:Bde:f:hKP:STtu:vg:G:");
+		c = getopt(argc, argv, "b:Bde:f:hi:KP:STtu:vg:G:");
 		if (c < 0)
 			break;
 		switch (c) {
@@ -677,6 +725,11 @@ int main(int argc, char *argv[])
 		case 'u':
 			return gen_uuid(optarg);
 #endif /* CONFIG_WPS */
+		case 'i':
+			if (hostapd_get_interface_names(&if_names,
+							&if_names_size, optarg))
+				goto out;
+			break;
 		default:
 			usage();
 			break;
@@ -734,7 +787,13 @@ int main(int argc, char *argv[])
 
 	/* Allocate and parse configuration for full interface files */
 	for (i = 0; i < interfaces.count; i++) {
+		char *if_name = NULL;
+
+		if (i < if_names_size)
+			if_name = if_names[i];
+
 		interfaces.iface[i] = hostapd_interface_init(&interfaces,
+							     if_name,
 							     argv[optind + i],
 							     debug);
 		if (!interfaces.iface[i]) {
@@ -829,6 +888,10 @@ int main(int argc, char *argv[])
 
 	os_free(bss_config);
 
+	for (i = 0; i < if_names_size; i++)
+		os_free(if_names[i]);
+	os_free(if_names);
+
 	fst_global_deinit();
 
 	os_program_deinit();