zebra: set ZEBRA_IFC_DOWN on connected routes for inactive interfaces

If you are in a situation where you have multiple addresses on an
interface, zebra creates one connected route for them.
The issue is that the rib entry is not created if addresses were
added before the interface was running.

We add the address to a running interface in a typical flow.
Therefore, we handle the route & rib creation within a single ADD event.
In the opposite case, we create the route entries without activating them.
These are considered to be active since ZEBRA_IFC_DOWN is not set.
On the following interface UP, we ignore the same ADDR_ADD as it overlaps
with the existing prefixes -> rib is never created.

The minimal reproducible setup:
-----------------------------------------
ip link add name dummy0 type dummy
ip addr flush dev dummy0
ip link set dummy0 down
ip addr add 192.168.1.7/24 dev dummy0
ip addr add 192.168.1.8/24 dev dummy0
ip link set dummy0 up
vtysh -c 'show ip route' | grep dummy0

Signed-off-by: Volodymyr Huti <v.huti@vyos.io>
(cherry picked from commit 7fb9825cf7e762add68f5108df4eddda1247f198)

diff --git a/zebra/connected.c b/zebra/connected.c
index b261ddb7914de009b27ad483ba136ea6826e7161..dc8bf0f1f36fe79fa7da2f5d7fdc65fe9220c3e3 100644 (file)
--- a/zebra/connected.c
+++ b/zebra/connected.c
@@ -325,6 +325,8 @@ void connected_add_ipv4(struct interface *ifp, int flags,
        /* If we get a notification from the kernel,
         * we can safely assume the address is known to the kernel */
        SET_FLAG(ifc->conf, ZEBRA_IFC_QUEUED);
+       if (!if_is_operative(ifp))
+               SET_FLAG(ifc->conf, ZEBRA_IFC_DOWN);
 
        /* Allocate new connected address. */
        p = prefix_ipv4_new();
@@ -546,6 +548,8 @@ void connected_add_ipv6(struct interface *ifp, int flags,
        /* If we get a notification from the kernel,
         * we can safely assume the address is known to the kernel */
        SET_FLAG(ifc->conf, ZEBRA_IFC_QUEUED);
+       if (!if_is_operative(ifp))
+               SET_FLAG(ifc->conf, ZEBRA_IFC_DOWN);
 
        /* Allocate new connected address. */
        p = prefix_ipv6_new();