lib: fix next vrf interface lookup avoid loopback interface

When the default vrf is submitted, the returned interface
may be the loopback interface, which may not be valid.
Actually, on vrfs, the vrf interface is bypassed. When
being on default vrf, the 'lo' interface should be
bypassed too.
Fix this by avoiding returning the lo interface too.

Fixes: 0760a74 ("lib: add utility to get the next index in a vrf")

Signed-off-by: Philippe Guibert <[email protected]>

lib/if.c

@@ -322,17 +322,17 @@ struct interface *if_vrf_lookup_by_index_next(ifindex_t ifindex,
 
 	if (ifindex == 0) {
 		tmp_ifp = RB_MIN(if_index_head, &vrf->ifaces_by_index);
-		/* skip the vrf interface */
-		if (tmp_ifp && if_is_vrf(tmp_ifp))
+		/* skip the vrf interface or the lo interface */
+		if (tmp_ifp && if_is_loopback(tmp_ifp))
 			ifindex = tmp_ifp->ifindex;
 		else
 			return tmp_ifp;
 	}
 
 	RB_FOREACH (tmp_ifp, if_index_head, &vrf->ifaces_by_index) {
 		if (found) {
-			/* skip the vrf interface */
-			if (tmp_ifp && if_is_vrf(tmp_ifp))
+			/* skip the vrf interface or the lo interface */
+			if (tmp_ifp && if_is_loopback(tmp_ifp))
 				continue;
 			else
 				return tmp_ifp;