platform: rework link type detection for better fallback (bgo #743209)

See "Revert "wireless: Support of IFLA_INFO_KIND rtnl attribute""
http://www.spinics.net/lists/linux-wireless/msg132219.html

The reverted kernel patch caused rtnl_link_get_type() to return "wlan"
for WiFi devices.  Since NM depends on this function returning
NULL for WiFi devices so that it goes on to check the sysfs DEVTYPE
attribute, the kernel patch caused WiFi devices to show up as Generic
ones instead.  That's wrong, and NM should be able to more easily
handle changes in the kernel drivers from NULL to a more descriptive
rtnl_link_get_type() return, since that's the kernel trend.

What NM should be doing here is to fall back to other detection
schemes if the type is NULL or unrecognized. Make that happen and
clean things up to use a table instead of a giant if(strcmp()) block.

https://bugzilla.gnome.org/show_bug.cgi?id=743209

src/platform/nm-linux-platform.c

@@ -951,31 +951,55 @@ read_devtype (const char *sysfs_path)
 static NMLinkType
 link_extract_type (NMPlatform *platform, struct rtnl_link *rtnllink, const char **out_name)
 {
-	const char *type;
+	const char *rtnl_type, *ifname;
+	int i, arptype;
 
 	if (!rtnllink)
 		return_type (NM_LINK_TYPE_NONE, NULL);
 
-	type = rtnl_link_get_type (rtnllink);
+	rtnl_type = rtnl_link_get_type (rtnllink);
+	if (rtnl_type) {
+		for (i = 0; i < G_N_ELEMENTS (linktypes); i++) {
+			if (g_strcmp0 (rtnl_type, linktypes[i].rtnl_type) == 0)
+				return_type (linktypes[i].nm_type, linktypes[i].type_string);
+		}
 
-	if (!type) {
+		if (!strcmp (rtnl_type, "tun")) {
-		int arptype = rtnl_link_get_arptype (rtnllink);
+			NMPlatformTunProperties props;
-		const char *driver;
+			guint flags;
-		const char *ifname;
+
-		gs_free char *anycast_mask = NULL;
+			if (nm_platform_tun_get_properties (platform, rtnl_link_get_ifindex (rtnllink), &props)) {
+				if (!g_strcmp0 (props.mode, "tap"))
+					return_type (NM_LINK_TYPE_TAP, "tap");
+				if (!g_strcmp0 (props.mode, "tun"))
+					return_type (NM_LINK_TYPE_TUN, "tun");
+			}
+			flags = rtnl_link_get_flags (rtnllink);
+
+			nm_log_dbg (LOGD_PLATFORM, "Failed to read tun properties for interface %d (link flags: %X)",
+			            rtnl_link_get_ifindex (rtnllink), flags);
+
+			/* try guessing the type using the link flags instead... */
+			if (flags & IFF_POINTOPOINT)
+				return_type (NM_LINK_TYPE_TUN, "tun");
+			return_type (NM_LINK_TYPE_TAP, "tap");
+		}
+	}
+
+	arptype = rtnl_link_get_arptype (rtnllink);
+	if (arptype == ARPHRD_LOOPBACK)
+		return_type (NM_LINK_TYPE_LOOPBACK, "loopback");
+	else if (arptype == ARPHRD_INFINIBAND)
+		return_type (NM_LINK_TYPE_INFINIBAND, "infiniband");
+
+
+	ifname = rtnl_link_get_name (rtnllink);
+	if (ifname) {
+		const char *driver = ethtool_get_driver (ifname);
 		gs_free char *sysfs_path = NULL;
+		gs_free char *anycast_mask = NULL;
 		gs_free char *devtype = NULL;
 
-		if (arptype == ARPHRD_LOOPBACK)
-			return_type (NM_LINK_TYPE_LOOPBACK, "loopback");
-		else if (arptype == ARPHRD_INFINIBAND)
-			return_type (NM_LINK_TYPE_INFINIBAND, "infiniband");
-
-		ifname = rtnl_link_get_name (rtnllink);
-		if (!ifname)
-			return_type (NM_LINK_TYPE_UNKNOWN, type);
-
-		driver = ethtool_get_driver (ifname);
 		if (arptype == 256) {
 			/* Some s390 CTC-type devices report 256 for the encapsulation type
 			 * for some reason, but we need to call them Ethernet.
@@ -984,6 +1008,7 @@ link_extract_type (NMPlatform *platform, struct rtnl_link *rtnllink, const char
 				return_type (NM_LINK_TYPE_ETHERNET, "ethernet");
 		}
 
+		/* Fallback OVS detection for kernel <= 3.16 */
 		if (!g_strcmp0 (driver, "openvswitch"))
 			return_type (NM_LINK_TYPE_OPENVSWITCH, "openvswitch");
 
@@ -993,64 +1018,25 @@ link_extract_type (NMPlatform *platform, struct rtnl_link *rtnllink, const char
 			return_type (NM_LINK_TYPE_OLPC_MESH, "olpc-mesh");
 
 		devtype = read_devtype (sysfs_path);
-		if (devtype) {
+		for (i = 0; devtype && i < G_N_ELEMENTS (linktypes); i++) {
-			if (wifi_utils_is_wifi (ifname, sysfs_path, devtype))
+			if (g_strcmp0 (devtype, linktypes[i].devtype) == 0)
-				return_type (NM_LINK_TYPE_WIFI, "wifi");
+				return_type (linktypes[i].nm_type, linktypes[i].type_string);
-			else if (g_strcmp0 (devtype, "wwan") == 0)
-				return_type (NM_LINK_TYPE_WWAN_ETHERNET, "wwan");
-			else if (g_strcmp0 (devtype, "wimax") == 0)
-				return_type (NM_LINK_TYPE_WIMAX, "wimax");
 		}
 
-		if (arptype == ARPHRD_ETHER)
+		/* Fallback for drivers that don't call SET_NETDEV_DEVTYPE() */
+		if (wifi_utils_is_wifi (ifname, sysfs_path))
+			return_type (NM_LINK_TYPE_WIFI, "wifi");
+
+		/* Standard wired ethernet interfaces don't report an rtnl_link_type, so
+		 * only allow fallback to Ethernet if no type is given.  This should
+		 * prevent future virtual network drivers from being treated as Ethernet
+		 * when they should be Generic instead.
+		 */
+		if (arptype == ARPHRD_ETHER && !rtnl_type && !devtype)
 			return_type (NM_LINK_TYPE_ETHERNET, "ethernet");
+	}
 
-		return_type (NM_LINK_TYPE_UNKNOWN, "unknown");
+	return_type (NM_LINK_TYPE_UNKNOWN, rtnl_type ? rtnl_type : "unknown");
-	} else if (!strcmp (type, "dummy"))
-		return_type (NM_LINK_TYPE_DUMMY, "dummy");
-	else if (!strcmp (type, "gre"))
-		return_type (NM_LINK_TYPE_GRE, "gre");
-	else if (!strcmp (type, "gretap"))
-		return_type (NM_LINK_TYPE_GRETAP, "gretap");
-	else if (!strcmp (type, "ifb"))
-		return_type (NM_LINK_TYPE_IFB, "ifb");
-	else if (!strcmp (type, "macvlan"))
-		return_type (NM_LINK_TYPE_MACVLAN, "macvlan");
-	else if (!strcmp (type, "macvtap"))
-		return_type (NM_LINK_TYPE_MACVTAP, "macvtap");
-	else if (!strcmp (type, "tun")) {
-		NMPlatformTunProperties props;
-		guint flags;
-
-		if (nm_platform_tun_get_properties (platform, rtnl_link_get_ifindex (rtnllink), &props)) {
-			if (!g_strcmp0 (props.mode, "tap"))
-				return_type (NM_LINK_TYPE_TAP, "tap");
-			if (!g_strcmp0 (props.mode, "tun"))
-				return_type (NM_LINK_TYPE_TUN, "tun");
-		}
-		flags = rtnl_link_get_flags (rtnllink);
-
-		nm_log_dbg (LOGD_PLATFORM, "Failed to read tun properties for interface %d (link flags: %X)",
-		                           rtnl_link_get_ifindex (rtnllink), flags);
-
-		/* try guessing the type using the link flags instead... */
-		if (flags & IFF_POINTOPOINT)
-			return_type (NM_LINK_TYPE_TUN, "tun");
-		return_type (NM_LINK_TYPE_TAP, "tap");
-	} else if (!strcmp (type, "veth"))
-		return_type (NM_LINK_TYPE_VETH, "veth");
-	else if (!strcmp (type, "vlan"))
-		return_type (NM_LINK_TYPE_VLAN, "vlan");
-	else if (!strcmp (type, "vxlan"))
-		return_type (NM_LINK_TYPE_VXLAN, "vxlan");
-	else if (!strcmp (type, "bridge"))
-		return_type (NM_LINK_TYPE_BRIDGE, "bridge");
-	else if (!strcmp (type, "bond"))
-		return_type (NM_LINK_TYPE_BOND, "bond");
-	else if (!strcmp (type, "team"))
-		return_type (NM_LINK_TYPE_TEAM, "team");
-
-	return_type (NM_LINK_TYPE_UNKNOWN, type);
 }
 
 static gboolean

src/platform/wifi/wifi-utils.c

@@ -170,20 +170,13 @@ wifi_utils_deinit (WifiData *data)
 }
 
 gboolean
-wifi_utils_is_wifi (const char *iface, const char *sysfs_path, const char *devtype)
+wifi_utils_is_wifi (const char *iface, const char *sysfs_path)
 {
 	char phy80211_path[255];
 	struct stat s;
 
 	g_return_val_if_fail (iface != NULL, FALSE);
 
-	if (g_strcmp0 (devtype, "wlan") == 0) {
-		/* All Wi-Fi drivers should set DEVTYPE=wlan.  Since the kernel's
-		 * cfg80211/nl80211 stack does, this check should match any nl80211
-		 * capable driver (including mac82011-based ones). */
-		return TRUE;
-	}
-
 	if (sysfs_path) {
 		/* Check for nl80211 sysfs paths */
 		g_snprintf (phy80211_path, sizeof (phy80211_path), "%s/phy80211", sysfs_path);

src/platform/wifi/wifi-utils.h

@@ -29,7 +29,7 @@
 
 typedef struct WifiData WifiData;
 
-gboolean wifi_utils_is_wifi (const char *iface, const char *sysfs_path, const char *devtype);
+gboolean wifi_utils_is_wifi (const char *iface, const char *sysfs_path);
 
 WifiData *wifi_utils_init (const char *iface, int ifindex, gboolean check_scan);