wext: Add support for renamed Host AP driver ifname

Previous workaround for WEXT events from the Host AP driver required
wlan# and wifi# interfaces to have fixed names with the same number.
While that used to be the common case ten years ago, it is less common
nowadays. Extend this to use sysfs (if available) to figure out the
wifi# interface name if the specified interface is detected to be using
the Host AP driver.

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

src/drivers/driver_wext.c

@@ -1,6 +1,6 @@
 /*
  * Driver interaction with generic Linux Wireless Extensions
- * Copyright (c) 2003-2010, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2003-2015, Jouni Malinen <j@w1.fi>
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -18,6 +18,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <net/if_arp.h>
+#include <dirent.h>
 
 #include "linux_wext.h"
 #include "common.h"
@@ -874,6 +875,105 @@ static void wpa_driver_wext_send_rfkill(void *eloop_ctx, void *timeout_ctx)
 }
 
 
+static int wext_hostap_ifname(struct wpa_driver_wext_data *drv,
+			      const char *ifname)
+{
+	char buf[200], *res;
+	int type;
+	FILE *f;
+
+	if (strcmp(ifname, ".") == 0 || strcmp(ifname, "..") == 0)
+		return -1;
+
+	snprintf(buf, sizeof(buf), "/sys/class/net/%s/device/net/%s/type",
+		 drv->ifname, ifname);
+
+	f = fopen(buf, "r");
+	if (!f)
+		return -1;
+	res = fgets(buf, sizeof(buf), f);
+	fclose(f);
+
+	type = res ? atoi(res) : -1;
+	wpa_printf(MSG_DEBUG, "WEXT: hostap ifname %s type %d", ifname, type);
+
+	if (type == ARPHRD_IEEE80211) {
+		wpa_printf(MSG_DEBUG,
+			   "WEXT: Found hostap driver wifi# interface (%s)",
+			   ifname);
+		wpa_driver_wext_alternative_ifindex(drv, ifname);
+		return 0;
+	}
+	return -1;
+}
+
+
+static int wext_add_hostap(struct wpa_driver_wext_data *drv)
+{
+	char buf[200];
+	int n;
+	struct dirent **names;
+	int ret = -1;
+
+	snprintf(buf, sizeof(buf), "/sys/class/net/%s/device/net", drv->ifname);
+	n = scandir(buf, &names, NULL, alphasort);
+	if (n < 0)
+		return -1;
+
+	while (n--) {
+		if (ret < 0 && wext_hostap_ifname(drv, names[n]->d_name) == 0)
+			ret = 0;
+		free(names[n]);
+	}
+	free(names);
+
+	return ret;
+}
+
+
+static void wext_check_hostap(struct wpa_driver_wext_data *drv)
+{
+	char buf[200], *pos;
+	ssize_t res;
+
+	/*
+	 * Host AP driver may use both wlan# and wifi# interface in wireless
+	 * events. Since some of the versions included WE-18 support, let's add
+	 * the alternative ifindex also from driver_wext.c for the time being.
+	 * This may be removed at some point once it is believed that old
+	 * versions of the driver are not in use anymore. However, it looks like
+	 * the wifi# interface is still used in the current kernel tree, so it
+	 * may not really be possible to remove this before the Host AP driver
+	 * gets removed from the kernel.
+	 */
+
+	/* First, try to see if driver information is available from sysfs */
+	snprintf(buf, sizeof(buf), "/sys/class/net/%s/device/driver",
+		 drv->ifname);
+	res = readlink(buf, buf, sizeof(buf) - 1);
+	if (res > 0) {
+		buf[res] = '\0';
+		pos = strrchr(buf, '/');
+		if (pos)
+			pos++;
+		else
+			pos = buf;
+		wpa_printf(MSG_DEBUG, "WEXT: Driver: %s", pos);
+		if (os_strncmp(pos, "hostap", 6) == 0 &&
+		    wext_add_hostap(drv) == 0)
+			return;
+	}
+
+	/* Second, use the old design with hardcoded ifname */
+	if (os_strncmp(drv->ifname, "wlan", 4) == 0) {
+		char ifname2[IFNAMSIZ + 1];
+		os_strlcpy(ifname2, drv->ifname, sizeof(ifname2));
+		os_memcpy(ifname2, "wifi", 4);
+		wpa_driver_wext_alternative_ifindex(drv, ifname2);
+	}
+}
+
+
 static int wpa_driver_wext_finish_drv_init(struct wpa_driver_wext_data *drv)
 {
 	int send_rfkill_event = 0;
@@ -914,20 +1014,7 @@ static int wpa_driver_wext_finish_drv_init(struct wpa_driver_wext_data *drv)
 
 	drv->ifindex = if_nametoindex(drv->ifname);
 
-	if (os_strncmp(drv->ifname, "wlan", 4) == 0) {
-		/*
-		 * Host AP driver may use both wlan# and wifi# interface in
-		 * wireless events. Since some of the versions included WE-18
-		 * support, let's add the alternative ifindex also from
-		 * driver_wext.c for the time being. This may be removed at
-		 * some point once it is believed that old versions of the
-		 * driver are not in use anymore.
-		 */
-		char ifname2[IFNAMSIZ + 1];
-		os_strlcpy(ifname2, drv->ifname, sizeof(ifname2));
-		os_memcpy(ifname2, "wifi", 4);
-		wpa_driver_wext_alternative_ifindex(drv, ifname2);
-	}
+	wext_check_hostap(drv);
 
 	netlink_send_oper_ifla(drv->netlink, drv->ifindex,
 			       1, IF_OPER_DORMANT);