interfaces: T6592: moving an interface between VRF instances failed

To reproduce:

    set vrf name mgmt table '150'
    set vrf name no-mgmt table '151'
    set interfaces ethernet eth2 vrf 'mgmt'
    commit

    set interfaces ethernet eth2 vrf no-mgmt
    commit

This resulted in an error while interacting with nftables:
[Errno 1] failed to run command: nft add element inet vrf_zones ct_iface_map { "eth2" : 151 }

The reason is that the old mapping entry still exists and was not removed.

This commit adds a new utility function get_vrf_tableid() and compares the
current and new VRF table IDs assigned to an interface. If the IDs do not
match, the nftables ct_iface_map entry is removed before the new entry is added.

1 files changed, 18 insertions, 5 deletions

diff --git a/python/vyos/utils/network.py b/python/vyos/utils/network.py
index 829124b57..8406a5638 100644
--- a/python/vyos/utils/network.py
+++ b/python/vyos/utils/network.py
@@ -83,6 +83,19 @@ def get_interface_vrf(interface):
         return tmp['master']
     return 'default'
 
+def get_vrf_tableid(interface: str):
+    """ Return VRF table ID for given interface name or None """
+    from vyos.utils.dict import dict_search
+    table = None
+    tmp = get_interface_config(interface)
+    # Check if we are "the" VRF interface
+    if dict_search('linkinfo.info_kind', tmp) == 'vrf':
+        table = tmp['linkinfo']['info_data']['table']
+    # or an interface bound to a VRF
+    elif dict_search('linkinfo.info_slave_kind', tmp) == 'vrf':
+        table = tmp['linkinfo']['info_slave_data']['table']
+    return table
+
 def get_interface_config(interface):
     """ Returns the used encapsulation protocol for given interface.
         If interface does not exist, None is returned.
@@ -537,21 +550,21 @@ def ipv6_prefix_length(low, high):
         return None
 
     xor = bytearray(a ^ b for a, b in zip(lo, hi))
-        
+
     plen = 0
     while plen < 128 and xor[plen // 8] == 0:
         plen += 8
-        
+
     if plen == 128:
         return plen
-    
+
     for i in range((plen // 8) + 1, 16):
         if xor[i] != 0:
             return None
-    
+
     for i in range(8):
         msk = ~xor[plen // 8] & 0xff
-        
+
         if msk == bytemasks[i]:
             return plen + i + 1