net: Dump veth device

These devices can be distinguished by type ETHER and kind "veth".
Some problems with peer detection exists (described in comment), but
we cannot handle them at the moment.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

net.c

@@ -37,6 +37,39 @@ static int dump_one_netdev(int type, struct ifinfomsg *ifi,
 	return pb_write_one(fdset_fd(fds, CR_FD_NETDEV), &netdev, PB_NETDEV);
 }
 
+static int dump_one_ethernet(struct ifinfomsg *ifi,
+		struct rtattr **tb, struct cr_fdset *fds)
+{
+	struct rtattr *linkinfo[IFLA_INFO_MAX + 1];
+	char *kind;
+
+	if (!tb[IFLA_LINKINFO]) {
+		pr_err("No linkinfo for eth link %d\n", ifi->ifi_index);
+		return -1;
+	}
+
+	parse_rtattr_nested(linkinfo, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);
+	if (!linkinfo[IFLA_INFO_KIND]) {
+		pr_err("No kind for eth link %d\n", ifi->ifi_index);
+		return -1;
+	}
+
+	kind = RTA_DATA(linkinfo[IFLA_INFO_KIND]);
+	if (!strcmp(kind, "veth"))
+		/*
+		 * This is not correct. The peer of the veth device may
+		 * be either outside or inside the netns we're working
+		 * on, but there's currently no way of finding this out.
+		 *
+		 * Sigh... we have to assume, that the veth device is a
+		 * connection to the outer world and just dump this end :(
+		 */
+		return dump_one_netdev(ND_TYPE__VETH, ifi, tb, fds);
+
+	pr_err("Unknown eth kind %s link %d\n", kind, ifi->ifi_index);
+	return -1;
+}
+
 static int dump_one_link(struct nlmsghdr *hdr, void *arg)
 {
 	struct cr_fdset *fds = arg;
@@ -59,6 +92,9 @@ static int dump_one_link(struct nlmsghdr *hdr, void *arg)
 	case ARPHRD_LOOPBACK:
 		ret = dump_one_netdev(ND_TYPE__LOOPBACK, ifi, tb, fds);
 		break;
+	case ARPHRD_ETHER:
+		ret = dump_one_ethernet(ifi, tb, fds);
+		break;
 	default:
 		pr_err("Unsupported link type %d\n", ifi->ifi_type);
 		ret = 0; /* just skip for now */
@@ -134,6 +170,8 @@ static int restore_link(NetDeviceEntry *nde, int nlsk)
 	switch (nde->type) {
 	case ND_TYPE__LOOPBACK:
 		return restore_one_link(nde, nlsk);
+	case ND_TYPE__VETH:
+		break;
 	}
 
 	BUG_ON(1);

protobuf/netdev.proto

 enum nd_type {
 	LOOPBACK	= 1;
+	VETH		= 2;
 }
 
 message net_device_entry {