images: add a network namespace id into images

It is possible to assign id for network namespaces and
this id will be used by the kernel in some netlink messages.
If no id is assigned when the kernel needs it, it will be
automatically assigned by the kernel.

For example, this id is reported for peer veth devices.

v2: add a comment
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

images/netdev.proto

@@ -42,9 +42,22 @@ message net_device_entry {
 
 	optional macvlan_link_entry	macvlan		= 11;
 
+	optional uint32 peer_ifindex	= 12;
+	optional uint32 peer_nsid	= 13;
 	optional sit_entry sit		= 15;
 }
 
+message netns_id {
+	/* This is CRIU's id which is allocated for each namespace */
+	required uint32	target_ns_id	= 1;
+	/*
+	 * This is an id which can be used to address this namespace
+	 * from another network namespace. Each network namespace has
+	 * one set of id-s for other namespaces.
+	 */
+	required int32	netnsid_value	= 2;
+}
+
 message netns_entry {
 	repeated int32 def_conf		= 1;
 	repeated int32 all_conf		= 2;
@@ -54,4 +67,6 @@ message netns_entry {
 
 	repeated sysctl_entry def_conf6	= 5;
 	repeated sysctl_entry all_conf6	= 6;
+
+	repeated netns_id nsids		= 7;
 }