zebra: set connected route metric based on the devaddr metric

MACVLAN devices are typically used for applications such as VRR/VRRP that
require a second MAC address (virtual). These devices have a corresponding
SVI/VLAN device -
root@TORC11:~# ip addr show vlan1002
39: vlan1002@bridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9152 qdisc noqueue master vrf1 state UP group default
    link/ether 00:02:00:00:00:2e brd ff:ff:ff:ff:ff:ff
    inet6 2001:aa:1::2/64 scope global
       valid_lft forever preferred_lft forever
root@TORC11:~# ip addr show vlan1002-v0
40: vlan1002-v0@vlan1002: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9152 qdisc noqueue master vrf1 state UP group default
    link/ether 00:00:5e:00:01:01 brd ff:ff:ff:ff:ff:ff
    inet6 2001:aa:1::a/64 metric 1024 scope global
       valid_lft forever preferred_lft forever
root@TORC11:~#

The macvlan device is used primarily for RX (VR-IP/VR-MAC). And TX is via
the SVI. To acheive that functionality the macvlan network's metric
is set to a higher value.

Zebra currently ignores the devaddr metric sent by the kernel and hardcodes
it to 0. This commit eliminates that hardcoding. If the devaddr metric
is available (METRIC_MAX) it is used for setting up the connected route
otherwise we fallback to the dev/interface metric.

Setting the macvlan metric to a higher value ensures that zebra will always
select the connected route on the SVI (and subsequently use it for next hop
resolution etc.) -
root@TORC11:~# vtysh -c "show ip route vrf vrf1 2001:aa:1::/64"
Routing entry for 2001:aa:1::/64
  Known via "connected", distance 0, metric 1024, vrf vrf1
  Last update 11:30:56 ago
  * directly connected, vlan1002-v0

Routing entry for 2001:aa:1::/64
  Known via "connected", distance 0, metric 0, vrf vrf1, best
  Last update 11:30:56 ago
  * directly connected, vlan1002

root@TORC11:~#

Ticket: CM-23511
Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/include/linux/if_addr.h b/include/linux/if_addr.h
new file mode 100644
index 0000000000..a924606f36
--- /dev/null
+++ b/include/linux/if_addr.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef __LINUX_IF_ADDR_H
+#define __LINUX_IF_ADDR_H
+
+#include <linux/types.h>
+#include <linux/netlink.h>
+
+struct ifaddrmsg {
+	__u8		ifa_family;
+	__u8		ifa_prefixlen;	/* The prefix length		*/
+	__u8		ifa_flags;	/* Flags			*/
+	__u8		ifa_scope;	/* Address scope		*/
+	__u32		ifa_index;	/* Link index			*/
+};
+
+/*
+ * Important comment:
+ * IFA_ADDRESS is prefix address, rather than local interface address.
+ * It makes no difference for normally configured broadcast interfaces,
+ * but for point-to-point IFA_ADDRESS is DESTINATION address,
+ * local address is supplied in IFA_LOCAL attribute.
+ *
+ * IFA_FLAGS is a u32 attribute that extends the u8 field ifa_flags.
+ * If present, the value from struct ifaddrmsg will be ignored.
+ */
+enum {
+	IFA_UNSPEC,
+	IFA_ADDRESS,
+	IFA_LOCAL,
+	IFA_LABEL,
+	IFA_BROADCAST,
+	IFA_ANYCAST,
+	IFA_CACHEINFO,
+	IFA_MULTICAST,
+	IFA_FLAGS,
+	IFA_RT_PRIORITY,  /* u32, priority/metric for prefix route */
+	__IFA_MAX,
+};
+
+#define IFA_MAX (__IFA_MAX - 1)
+
+/* ifa_flags */
+#define IFA_F_SECONDARY		0x01
+#define IFA_F_TEMPORARY		IFA_F_SECONDARY
+
+#define	IFA_F_NODAD		0x02
+#define IFA_F_OPTIMISTIC	0x04
+#define IFA_F_DADFAILED		0x08
+#define	IFA_F_HOMEADDRESS	0x10
+#define IFA_F_DEPRECATED	0x20
+#define IFA_F_TENTATIVE		0x40
+#define IFA_F_PERMANENT		0x80
+#define IFA_F_MANAGETEMPADDR	0x100
+#define IFA_F_NOPREFIXROUTE	0x200
+#define IFA_F_MCAUTOJOIN	0x400
+#define IFA_F_STABLE_PRIVACY	0x800
+
+struct ifa_cacheinfo {
+	__u32	ifa_prefered;
+	__u32	ifa_valid;
+	__u32	cstamp; /* created timestamp, hundredths of seconds */
+	__u32	tstamp; /* updated timestamp, hundredths of seconds */
+};
+
+/* backwards compatibility for userspace */
+#define IFA_RTA(r)  ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifaddrmsg))))
+#define IFA_PAYLOAD(n) NLMSG_PAYLOAD(n,sizeof(struct ifaddrmsg))
+
+#endif