tethering: Fix bridge module loading problem

Connman tries to check if bridging is supported by the kernel by checking
whether "/proc/sys/net/bridge" is present. If the bridge is a kernel
module which is not already loaded, then tethering cannot be enabled.

Instead of checking for the file we invoke the "get bridge version" socket
ioctl and the kernel will handle module loading issues - if the bridge
module is not loaded, it will first load it, and then check the version.

1 files changed, 12 insertions, 6 deletions

diff --git a/src/tethering.c b/src/tethering.c
index decb1122..b7343032 100644
--- a/src/tethering.c
+++ b/src/tethering.c
@@ -35,6 +35,7 @@
 #include <string.h>
 #include <fcntl.h>
 #include <linux/if_tun.h>
+#include <linux/if_bridge.h>
 
 #include "connman.h"
 
@@ -46,8 +47,6 @@
 #define DBUS_TYPE_UNIX_FD -1
 #endif
 
-#define BRIDGE_PROC_DIR "/proc/sys/net/bridge"
-
 #define BRIDGE_NAME "tether"
 #define BRIDGE_DNS "8.8.8.8"
 
@@ -79,12 +78,19 @@ struct connman_private_network {
 
 const char *__connman_tethering_get_bridge(void)
 {
-	struct stat st;
+	int sk, err;
+	unsigned long args[3];
 
-	if (stat(BRIDGE_PROC_DIR, &st) < 0) {
-		connman_error("Missing support for 802.1d ethernet bridging");
+	sk = socket(AF_INET, SOCK_STREAM, 0);
+	if (sk < 0)
+		return NULL;
+
+	args[0] = BRCTL_GET_VERSION;
+	args[1] = args[2] = 0;
+	err = ioctl(sk, SIOCGIFBR, &args);
+	close(sk);
+	if (err == -1)
 		return NULL;
-	}
 
 	return BRIDGE_NAME;
 }