networkd: introduce netdev ipvtap

This patch adds netdev ipvtap that is based on the
IP-VLAN network interface, called ipvtap. An ipvtap device can be created
in the same way as an ipvlan device, using 'kind ipvtap', and then accessed
using the tap user space interface.

src/network/netdev/ipvlan.c

@@ -32,7 +32,10 @@ static int netdev_ipvlan_fill_message_create(NetDev *netdev, Link *link, sd_netl
         assert(link);
         assert(netdev->ifname);
 
-        m = IPVLAN(netdev);
+        if (netdev->kind == NETDEV_KIND_IPVLAN)
+                m = IPVLAN(netdev);
+        else
+                m = IPVTAP(netdev);
 
         assert(m);
 
@@ -56,7 +59,10 @@ static void ipvlan_init(NetDev *n) {
 
         assert(n);
 
-        m = IPVLAN(n);
+        if (n->kind == NETDEV_KIND_IPVLAN)
+                m = IPVLAN(n);
+        else
+                m = IPVTAP(n);
 
         assert(m);
 
@@ -71,3 +77,11 @@ const NetDevVTable ipvlan_vtable = {
         .fill_message_create = netdev_ipvlan_fill_message_create,
         .create_type = NETDEV_CREATE_STACKED,
 };
+
+const NetDevVTable ipvtap_vtable = {
+        .object_size = sizeof(IPVlan),
+        .init = ipvlan_init,
+        .sections = "Match\0NetDev\0IPVTAP\0",
+        .fill_message_create = netdev_ipvlan_fill_message_create,
+        .create_type = NETDEV_CREATE_STACKED,
+};

src/network/netdev/ipvlan.h

@@ -30,7 +30,9 @@ typedef struct IPVlan {
 } IPVlan;
 
 DEFINE_NETDEV_CAST(IPVLAN, IPVlan);
+DEFINE_NETDEV_CAST(IPVTAP, IPVlan);
 extern const NetDevVTable ipvlan_vtable;
+extern const NetDevVTable ipvtap_vtable;
 
 const char *ipvlan_mode_to_string(IPVlanMode d) _const_;
 IPVlanMode ipvlan_mode_from_string(const char *d) _pure_;

src/network/netdev/netdev-gperf.gperf

@@ -54,6 +54,8 @@ MACVLAN.Mode,                             config_parse_macvlan_mode,
 MACVTAP.Mode,                             config_parse_macvlan_mode,                 0,                             offsetof(MacVlan, mode)
 IPVLAN.Mode,                              config_parse_ipvlan_mode,                  0,                             offsetof(IPVlan, mode)
 IPVLAN.Flags,                             config_parse_ipvlan_flags,                 0,                             offsetof(IPVlan, flags)
+IPVTAP.Mode,                              config_parse_ipvlan_mode,                  0,                             offsetof(IPVlan, mode)
+IPVTAP.Flags,                             config_parse_ipvlan_flags,                 0,                             offsetof(IPVlan, flags)
 Tunnel.Local,                             config_parse_tunnel_address,               0,                             offsetof(Tunnel, local)
 Tunnel.Remote,                            config_parse_tunnel_address,               0,                             offsetof(Tunnel, remote)
 Tunnel.TOS,                               config_parse_unsigned,                     0,                             offsetof(Tunnel, tos)

src/network/netdev/netdev.c

@@ -45,6 +45,7 @@ const NetDevVTable * const netdev_vtable[_NETDEV_KIND_MAX] = {
         [NETDEV_KIND_MACVLAN] = &macvlan_vtable,
         [NETDEV_KIND_MACVTAP] = &macvtap_vtable,
         [NETDEV_KIND_IPVLAN] = &ipvlan_vtable,
+        [NETDEV_KIND_IPVTAP] = &ipvtap_vtable,
         [NETDEV_KIND_VXLAN] = &vxlan_vtable,
         [NETDEV_KIND_IPIP] = &ipip_vtable,
         [NETDEV_KIND_GRE] = &gre_vtable,
@@ -78,6 +79,7 @@ static const char* const netdev_kind_table[_NETDEV_KIND_MAX] = {
         [NETDEV_KIND_MACVLAN] = "macvlan",
         [NETDEV_KIND_MACVTAP] = "macvtap",
         [NETDEV_KIND_IPVLAN] = "ipvlan",
+        [NETDEV_KIND_IPVTAP] = "ipvtap",
         [NETDEV_KIND_VXLAN] = "vxlan",
         [NETDEV_KIND_IPIP] = "ipip",
         [NETDEV_KIND_GRE] = "gre",

src/network/netdev/netdev.h

@@ -24,6 +24,7 @@ typedef enum NetDevKind {
         NETDEV_KIND_MACVLAN,
         NETDEV_KIND_MACVTAP,
         NETDEV_KIND_IPVLAN,
+        NETDEV_KIND_IPVTAP,
         NETDEV_KIND_VXLAN,
         NETDEV_KIND_IPIP,
         NETDEV_KIND_GRE,