zebra, ifp: on netlink discovery, anticipate the vrf creation

there may be cases where the vrf is yet allocated from the vty, and the
discovery process did not make the relationship between the vrf_id and
the name of the vrf. For instance, by parsing an interface belonging to
vrf-id X, it is not sure that vrf-id X and vrfname XX are talking about
the same vrf. For that, lets allocate the vrf, and lets try to detect
there is a duplicate case in vrf, so that the merge can be done without
any impact for the user.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

3 files changed, 22 insertions, 2 deletions

diff --git a/lib/if.c b/lib/if.c
index 0cfd591160..a803754375 100644
--- a/lib/if.c
+++ b/lib/if.c
@@ -177,6 +177,8 @@ void if_update_to_new_vrf(struct interface *ifp, vrf_id_t vrf_id)
 	if (ifp->ifindex != IFINDEX_INTERNAL)
 		IFINDEX_RB_INSERT(vrf, ifp);
 
+	if (!old_vrf->name)
+		return;
 	/*
 	 * HACK: Change the interface VRF in the running configuration directly,
 	 * bypassing the northbound layer. This is necessary to avoid deleting
diff --git a/lib/vrf.c b/lib/vrf.c
index 229f19f29a..862a3da067 100644
--- a/lib/vrf.c
+++ b/lib/vrf.c
@@ -176,6 +176,24 @@ struct vrf *vrf_get(vrf_id_t vrf_id, const char *name)
 			   name, vrf_id, vrf->vrf_id);
 		return NULL;
 	}
+	/* look for duplicates. case is followine one:
+	 * - a vrf is configured per name -> vrfA
+	 * - netlink discovery creates a vrf with vrf_id ->vrfB
+	 * - then, netlink discovers vrf, and associated vrf_id and name
+	 * -> so vrfA and vrfB must be merged
+	 */
+	if (vrf && vrf_id != VRF_UNKNOWN
+	    && vrf->vrf_id == VRF_UNKNOWN) {
+		struct vrf *vrf2 = vrf_lookup_by_id(vrf_id);
+		struct interface *ifp;
+
+		if (vrf2 && !vrf2->name && vrf2 != vrf) {
+			/* move vrf2 context to vrf */
+			FOR_ALL_INTERFACES (vrf2, ifp)
+				if_update_to_new_vrf(ifp, vrf);
+			vrf_delete(vrf2);
+		}
+	}
 	/* Try to find VRF both by ID and name */
 	if (!vrf && vrf_id != VRF_UNKNOWN)
 		vrf = vrf_lookup_by_id(vrf_id);
diff --git a/zebra/if_netlink.c b/zebra/if_netlink.c
index 4b998bcdc4..2c94dd52b5 100644
--- a/zebra/if_netlink.c
+++ b/zebra/if_netlink.c
@@ -665,6 +665,8 @@ static int netlink_interface(struct nlmsghdr *h, ns_id_t ns_id, int startup)
 		    && !vrf_is_backend_netns()) {
 			zif_slave_type = ZEBRA_IF_SLAVE_VRF;
 			vrf_id = *(uint32_t *)RTA_DATA(tb[IFLA_MASTER]);
+			/* vrf can be needed before vrf netlink discovery */
+			vrf_get(vrf_id, NULL);
 		} else if (slave_kind && (strcmp(slave_kind, "bridge") == 0)) {
 			zif_slave_type = ZEBRA_IF_SLAVE_BRIDGE;
 			bridge_ifindex =
@@ -677,9 +679,7 @@ static int netlink_interface(struct nlmsghdr *h, ns_id_t ns_id, int startup)
 	}
 	if (vrf_is_backend_netns())
 		vrf_id = (vrf_id_t)ns_id;
-
 	vrf = vrf_lookup_by_id(vrf_id);
-
 	/* If linking to another interface, note it. */
 	if (tb[IFLA_LINK])
 		link_ifindex = *(ifindex_t *)RTA_DATA(tb[IFLA_LINK]);