+ const struct netdev_class *class = netdev_get_dev(netdev)->netdev_class;
+ int error;
+
+ error = class->get_mtu ? class->get_mtu(netdev, mtup) : EOPNOTSUPP;
+ if (error) {
+ *mtup = 0;
+ if (error != EOPNOTSUPP) {
+ VLOG_WARN_RL(&rl, "failed to retrieve MTU for network device %s: "
+ "%s", netdev_get_name(netdev), strerror(error));
+ }
+ }
+ return error;
+}
+
+/* Sets the MTU of 'netdev'. The MTU is the maximum size of transmitted
+ * (and received) packets, in bytes.
+ *
+ * If successful, returns 0. Returns EOPNOTSUPP if 'netdev' does not have an
+ * MTU (as e.g. some tunnels do not). On other failure, returns a positive
+ * errno value. */
+int
+netdev_set_mtu(const struct netdev *netdev, int mtu)
+{
+ const struct netdev_class *class = netdev_get_dev(netdev)->netdev_class;
+ int error;
+
+ error = class->set_mtu ? class->set_mtu(netdev, mtu) : EOPNOTSUPP;
+ if (error && error != EOPNOTSUPP) {
+ VLOG_WARN_RL(&rl, "failed to retrieve MTU for network device %s: %s",
+ netdev_get_name(netdev), strerror(error));
+ }
+
+ return error;
+}
+
+/* Returns the ifindex of 'netdev', if successful, as a positive number. On
+ * failure, returns a negative errno value.
+ *
+ * The desired semantics of the ifindex value are a combination of those
+ * specified by POSIX for if_nametoindex() and by SNMP for ifIndex. An ifindex
+ * value should be unique within a host and remain stable at least until
+ * reboot. SNMP says an ifindex "ranges between 1 and the value of ifNumber"
+ * but many systems do not follow this rule anyhow.
+ *
+ * Some network devices may not implement support for this function. In such
+ * cases this function will always return -EOPNOTSUPP.
+ */
+int
+netdev_get_ifindex(const struct netdev *netdev)
+{
+ int (*get_ifindex)(const struct netdev *);
+
+ get_ifindex = netdev_get_dev(netdev)->netdev_class->get_ifindex;
+
+ return get_ifindex ? get_ifindex(netdev) : -EOPNOTSUPP;