lib: fix binding to a vrf

There are two possible use-cases for the `vrf_bind` function:
- bind socket to an interface in a vrf
- bind socket to a vrf device

For the former case, there's one problem - success is returned when the
interface is not found. In that case, the socket is left unbound without
throwing an error.

For the latter case, there are multiple possible problems:
- If the name is not set, then the socket is left unbound (zebra, vrrp).
- If the name is "default" and there's an interface with that name in the
  default VRF, then the socket is bound to that interface.
- In most daemons, if the router is configured before the VRF is actually
  created, we're trying to open and bind the socket right after the
  daemon receives a VRF registration from zebra. We may not receive the
  VRF-interface registration from zebra yet at that point. Therefore,
  `if_lookup_by_name` fails, and the socket is left unbound.

This commit fixes all the issues and updates the function description.

Suggested-by: Pat Ruddy <pat@voltanet.io>
Signed-off-by: Igor Ryzhov <iryzhov@nfware.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/tests/topotests/ospf6_topo1_vrf/test_ospf6_topo1_vrf.py b/tests/topotests/ospf6_topo1_vrf/test_ospf6_topo1_vrf.py
index fa2784ee7..e1857abc4 100755
--- a/tests/topotests/ospf6_topo1_vrf/test_ospf6_topo1_vrf.py
+++ b/tests/topotests/ospf6_topo1_vrf/test_ospf6_topo1_vrf.py
@@ -92,10 +92,7 @@ from lib import topotest
 from lib.topogen import Topogen, TopoRouter, get_topogen
 from lib.topolog import logger
 from lib.topotest import iproute2_is_vrf_capable
-from lib.common_config import (
-    required_linux_kernel_version,
-    adjust_router_l3mdev,
-)
+from lib.common_config import required_linux_kernel_version
 
 #####################################################
 ##
@@ -159,6 +156,11 @@ class NetworkTopo(Topo):
 def setup_module(mod):
     "Sets up the pytest environment"
 
+    # Required linux kernel version for this suite to run.
+    result = required_linux_kernel_version("5.0")
+    if result is not True:
+        pytest.skip("Kernel requirements are not met")
+
     tgen = Topogen(NetworkTopo, mod.__name__)
     tgen.start_topology()
 
@@ -197,9 +199,6 @@ def setup_module(mod):
             for cmd in cmds2:
                 output = tgen.net[rname].cmd(cmd.format(rname))
 
-        # adjust handling of vrf traffic
-        adjust_router_l3mdev(tgen, rname)
-
     for rname, router in tgen.routers().items():
         router.load_config(
             TopoRouter.RD_ZEBRA, os.path.join(CWD, "{}/zebra.conf".format(rname))