platform: refactor nm_platform_veth_get_properties()

For recent kernels, the peer-ifindex of veths is reported as
parent (IFA_LINK). Prefer that over the ethtool lookup.

For one, this avoids the extra ethtool call which has the
downside of sidestepping the platform cache. Also, looking
up the peer-ifindex in ethtool does not report whether the
peer lifes in another netns (NM_PLATFORM_LINK_OTHER_NETNS).

Only use ethtool as fallback for older kernels.

src/devices/nm-device-veth.c

@@ -76,17 +76,18 @@ get_peer (NMDeviceVeth *self)
 {
 	NMDeviceVethPrivate *priv = NM_DEVICE_VETH_GET_PRIVATE (self);
 	NMDevice *device = NM_DEVICE (self), *peer = NULL;
-	NMPlatformVethProperties props;
+	int peer_ifindex;
 
 	if (priv->ever_had_peer)
 		return priv->peer;
 
-	if (!nm_platform_veth_get_properties (NM_PLATFORM_GET, nm_device_get_ifindex (device), &props)) {
+	if (!nm_platform_veth_get_properties (NM_PLATFORM_GET, nm_device_get_ifindex (device), &peer_ifindex)) {
 		_LOGW (LOGD_HW, "could not read veth properties");
 		return NULL;
 	}
 
-	peer = nm_manager_get_device_by_ifindex (nm_manager_get (), props.peer);
+	if (peer_ifindex > 0)
+		peer = nm_manager_get_device_by_ifindex (nm_manager_get (), peer_ifindex);
 	if (peer && NM_IS_DEVICE_VETH (peer)) {
 		set_peer (self, peer);
 		set_peer (NM_DEVICE_VETH (peer), device);

src/platform/nm-fake-platform.c

@@ -701,12 +701,6 @@ infiniband_partition_add (NMPlatform *platform, int parent, int p_key, NMPlatfor
 	return TRUE;
 }
 
-static gboolean
-veth_get_properties (NMPlatform *platform, int ifindex, NMPlatformVethProperties *props)
-{
-	return FALSE;
-}
-
 static gboolean
 wifi_get_capabilities (NMPlatform *platform, int ifindex, NMDeviceWifiCapabilities *caps)
 {
@@ -1438,8 +1432,6 @@ nm_fake_platform_class_init (NMFakePlatformClass *klass)
 
 	platform_class->infiniband_partition_add = infiniband_partition_add;
 
-	platform_class->veth_get_properties = veth_get_properties;
-
 	platform_class->wifi_get_capabilities = wifi_get_capabilities;
 	platform_class->wifi_get_bssid = wifi_get_bssid;
 	platform_class->wifi_get_ssid = wifi_get_ssid;

src/platform/nm-linux-platform.c

@@ -3976,26 +3976,6 @@ infiniband_partition_add (NMPlatform *platform, int parent, int p_key, NMPlatfor
 
 /******************************************************************/
 
-static gboolean
-veth_get_properties (NMPlatform *platform, int ifindex, NMPlatformVethProperties *props)
-{
-	const char *ifname;
-	int peer_ifindex;
-
-	ifname = nm_platform_link_get_name (platform, ifindex);
-	if (!ifname)
-		return FALSE;
-
-	peer_ifindex = nmp_utils_ethtool_get_peer_ifindex (ifname);
-	if (peer_ifindex <= 0)
-		return FALSE;
-
-	props->peer = peer_ifindex;
-	return TRUE;
-}
-
-/******************************************************************/
-
 static WifiData *
 wifi_get_wifi_data (NMPlatform *platform, int ifindex)
 {
@@ -5223,8 +5203,6 @@ nm_linux_platform_class_init (NMLinuxPlatformClass *klass)
 
 	platform_class->infiniband_partition_add = infiniband_partition_add;
 
-	platform_class->veth_get_properties = veth_get_properties;
-
 	platform_class->wifi_get_capabilities = wifi_get_capabilities;
 	platform_class->wifi_get_bssid = wifi_get_bssid;
 	platform_class->wifi_get_frequency = wifi_get_frequency;

src/platform/nm-platform.c

@@ -1688,14 +1688,33 @@ nm_platform_infiniband_get_info (NMPlatform *self,
 }
 
 gboolean
-nm_platform_veth_get_properties (NMPlatform *self, int ifindex, NMPlatformVethProperties *props)
+nm_platform_veth_get_properties (NMPlatform *self, int ifindex, int *out_peer_ifindex)
 {
+	const NMPlatformLink *plink;
+	int peer_ifindex;
 	_CHECK_SELF (self, klass, FALSE);
 
-	g_return_val_if_fail (ifindex > 0, FALSE);
-	g_return_val_if_fail (props != NULL, FALSE);
+	plink = nm_platform_link_get (self, ifindex);
 
-	return klass->veth_get_properties (self, ifindex, props);
+	if (!plink)
+		return FALSE;
+	if (plink->type != NM_LINK_TYPE_VETH)
+		return FALSE;
+
+	if (plink->parent != 0) {
+		NM_SET_OUT (out_peer_ifindex, plink->parent);
+		return TRUE;
+	}
+
+	/* Pre-4.1 kernel did not expose the peer_ifindex as IFA_LINK. Lookup via ethtool. */
+	if (out_peer_ifindex) {
+		peer_ifindex = nmp_utils_ethtool_get_peer_ifindex (plink->name);
+		if (peer_ifindex <= 0)
+			return FALSE;
+
+		*out_peer_ifindex = peer_ifindex;
+	}
+	return TRUE;
 }
 
 gboolean

src/platform/nm-platform.h

@@ -350,10 +350,6 @@ typedef struct {
 	guint16 id;
 } NMPlatformLnkVlan;
 
-typedef struct {
-	int peer;
-} NMPlatformVethProperties;
-
 typedef struct {
 	gint64 owner;
 	gint64 group;
@@ -504,8 +500,6 @@ typedef struct {
 
 	gboolean (*infiniband_partition_add) (NMPlatform *, int parent, int p_key, NMPlatformLink *out_link);
 
-	gboolean (*veth_get_properties) (NMPlatform *, int ifindex, NMPlatformVethProperties *properties);
-
 	gboolean    (*wifi_get_capabilities) (NMPlatform *, int ifindex, NMDeviceWifiCapabilities *caps);
 	gboolean    (*wifi_get_bssid)        (NMPlatform *, int ifindex, guint8 *bssid);
 	GByteArray *(*wifi_get_ssid)         (NMPlatform *, int ifindex);
@@ -701,7 +695,7 @@ gboolean nm_platform_vlan_set_egress_map (NMPlatform *self, int ifindex, int fro
 NMPlatformError nm_platform_infiniband_partition_add (NMPlatform *self, int parent, int p_key, NMPlatformLink *out_link);
 gboolean nm_platform_infiniband_get_info (NMPlatform *self, int ifindex, int *parent, int *p_key, const char **mode);
 
-gboolean nm_platform_veth_get_properties        (NMPlatform *self, int ifindex, NMPlatformVethProperties *properties);
+gboolean nm_platform_veth_get_properties        (NMPlatform *self, int ifindex, int *out_peer_ifindex);
 gboolean nm_platform_tun_get_properties         (NMPlatform *self, int ifindex, NMPlatformTunProperties *properties);
 
 gboolean nm_platform_tun_get_properties_ifname  (NMPlatform *platform, const char *ifname, NMPlatformTunProperties *props);

src/platform/tests/platform.c

@@ -356,20 +356,6 @@ do_vlan_set_egress_map (char **argv)
 	return nm_platform_vlan_set_egress_map (NM_PLATFORM_GET, ifindex, from, to);
 }
 
-static gboolean
-do_veth_get_properties (char **argv)
-{
-	int ifindex = parse_ifindex (*argv++);
-	NMPlatformVethProperties props;
-
-	if (!nm_platform_veth_get_properties (NM_PLATFORM_GET, ifindex, &props))
-		return FALSE;
-
-	printf ("peer: %d\n", props.peer);
-
-	return TRUE;
-}
-
 static gboolean
 do_tun_get_properties (char **argv)
 {
@@ -825,8 +811,6 @@ static const command_t commands[] = {
 		"<ifname/ifindex> <from> <to>" },
 	{ "vlan-set-egress-map", "set vlan egress map", do_vlan_set_egress_map, 3,
 		"<ifname/ifindex> <from> <to>" },
-	{ "veth-get-properties", "get veth properties", do_veth_get_properties, 1,
-	  "<ifname/ifindex>" },
 	{ "tun-get-properties", "get tun/tap properties", do_tun_get_properties, 1,
 	  "<ifname/ifindex>" },
 	{ "macvlan-get-properties", "get macvlan properties", do_macvlan_get_properties, 1,