ip: link add vxcan support

Since commit a8f820a380a2a06 ('can: add Virtual CAN Tunnel driver (vxcan)')
for Linux 4.12 a virtual CAN tunnel driver analogue to veth is available in
Linux.

This patch adds the ability to create vxcan device pairs.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>

include/linux/can/vxcan.h

@@ -0,0 +1,12 @@
+#ifndef _CAN_VXCAN_H
+#define _CAN_VXCAN_H
+
+enum {
+	VXCAN_INFO_UNSPEC,
+	VXCAN_INFO_PEER,
+
+	__VXCAN_INFO_MAX
+#define VXCAN_INFO_MAX	(__VXCAN_INFO_MAX - 1)
+};
+
+#endif

ip/Makefile

@@ -2,7 +2,7 @@ IPOBJ=ip.o ipaddress.o ipaddrlabel.o iproute.o iprule.o ipnetns.o \
     rtm_map.o iptunnel.o ip6tunnel.o tunnel.o ipneigh.o ipntable.o iplink.o \
     ipmaddr.o ipmonitor.o ipmroute.o ipprefix.o iptuntap.o iptoken.o \
     ipxfrm.o xfrm_state.o xfrm_policy.o xfrm_monitor.o iplink_dummy.o \
-    iplink_ifb.o iplink_nlmon.o iplink_team.o iplink_vcan.o \
+    iplink_ifb.o iplink_nlmon.o iplink_team.o iplink_vcan.o iplink_vxcan.o \
     iplink_vlan.o link_veth.o link_gre.o iplink_can.o iplink_xdp.o \
     iplink_macvlan.o ipl2tp.o link_vti.o link_vti6.o \
     iplink_vxlan.o tcp_metrics.o iplink_ipoib.o ipnetconf.o link_ip6tnl.o \

ip/iplink_vxcan.c

@@ -0,0 +1,99 @@
+/*
+ * iplink_vxcan.c	vxcan device support (Virtual CAN Tunnel)
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ * Author:	Oliver Hartkopp <socketcan@hartkopp.net>
+ * Based on:	link_veth.c from Pavel Emelianov <xemul@openvz.org>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <net/if.h>
+#include <linux/can/vxcan.h>
+
+#include "utils.h"
+#include "ip_common.h"
+
+static void print_usage(FILE *f)
+{
+	printf("Usage: ip link <options> type vxcan [peer <options>]\n"
+	       "To get <options> type 'ip link add help'\n");
+}
+
+static void usage(void)
+{
+	print_usage(stderr);
+}
+
+static int vxcan_parse_opt(struct link_util *lu, int argc, char **argv,
+			  struct nlmsghdr *hdr)
+{
+	char *dev = NULL;
+	char *name = NULL;
+	char *link = NULL;
+	char *type = NULL;
+	int index = 0;
+	int err, len;
+	struct rtattr *data;
+	int group;
+	struct ifinfomsg *ifm, *peer_ifm;
+	unsigned int ifi_flags, ifi_change;
+
+	if (strcmp(argv[0], "peer") != 0) {
+		usage();
+		return -1;
+	}
+
+	ifm = NLMSG_DATA(hdr);
+	ifi_flags = ifm->ifi_flags;
+	ifi_change = ifm->ifi_change;
+	ifm->ifi_flags = 0;
+	ifm->ifi_change = 0;
+
+	data = NLMSG_TAIL(hdr);
+	addattr_l(hdr, 1024, VXCAN_INFO_PEER, NULL, 0);
+
+	hdr->nlmsg_len += sizeof(struct ifinfomsg);
+
+	err = iplink_parse(argc - 1, argv + 1, (struct iplink_req *)hdr,
+			   &name, &type, &link, &dev, &group, &index);
+	if (err < 0)
+		return err;
+
+	if (name) {
+		len = strlen(name) + 1;
+		if (len > IFNAMSIZ)
+			invarg("\"name\" too long\n", *argv);
+		addattr_l(hdr, 1024, IFLA_IFNAME, name, len);
+	}
+
+	peer_ifm = RTA_DATA(data);
+	peer_ifm->ifi_index = index;
+	peer_ifm->ifi_flags = ifm->ifi_flags;
+	peer_ifm->ifi_change = ifm->ifi_change;
+	ifm->ifi_flags = ifi_flags;
+	ifm->ifi_change = ifi_change;
+
+	if (group != -1)
+		addattr32(hdr, 1024, IFLA_GROUP, group);
+
+	data->rta_len = (void *)NLMSG_TAIL(hdr) - (void *)data;
+	return argc - 1 - err;
+}
+
+static void vxcan_print_help(struct link_util *lu, int argc, char **argv,
+	FILE *f)
+{
+	print_usage(f);
+}
+
+struct link_util vxcan_link_util = {
+	.id = "vxcan",
+	.parse_opt = vxcan_parse_opt,
+	.print_help = vxcan_print_help,
+};