vxlan: T5753: add support for VNI filtering

In a service provider network a service provider typically supports multiple
bridge domains with overlapping vlans. One bridge domain per customer. Vlans in
each bridge domain are mapped to globally unique VXLAN VNI ranges assigned to
each customer.

Without the ability of VNI filtering, we can not provide VXLAN tunnels
with multiple tenants all requiring e.g. VLAN 10.

To Test:

set interfaces vxlan vxlan987 parameters external
set interfaces vxlan vxlan987 source-interface eth0
set interfaces vxlan vxlan987 parameters vni-filter
set interfaces vxlan vxlan987 vlan-to-vni 50 vni 10050
set interfaces vxlan vxlan987 vlan-to-vni 51 vni 10051
set interfaces vxlan vxlan987 vlan-to-vni 52 vni 10052
set interfaces vxlan vxlan987 vlan-to-vni 53 vni 10053
set interfaces vxlan vxlan987 vlan-to-vni 54 vni 10054
set interfaces vxlan vxlan987 vlan-to-vni 60 vni 10060
set interfaces vxlan vxlan987 vlan-to-vni 69 vni 10069
set interfaces bridge br0 member interface vxlan987

Add new op-mode command: show bridge vni

Interface    VNI
-----------  -----------
vxlan987     10050-10054
vxlan987     10060
vxlan987     10069

1 files changed, 33 insertions, 0 deletions

diff --git a/python/vyos/utils/network.py b/python/vyos/utils/network.py
index 5d19f256b..6a5de5423 100644
--- a/python/vyos/utils/network.py
+++ b/python/vyos/utils/network.py
@@ -483,3 +483,36 @@ def get_vxlan_vlan_tunnels(interface: str) -> list:
             os_configured_vlan_ids.append(str(vlanStart))
 
     return os_configured_vlan_ids
+
+def get_vxlan_vni_filter(interface: str) -> list:
+    """ Return a list of strings with VNIs configured in the Kernel"""
+    from json import loads
+    from vyos.utils.process import cmd
+
+    if not interface.startswith('vxlan'):
+        raise ValueError('Only applicable for VXLAN interfaces!')
+
+    # Determine current OS Kernel configured VNI filters in VXLAN interface
+    #
+    # $ bridge -j vni show dev vxlan1
+    # [{"ifname":"vxlan1","vnis":[{"vni":100},{"vni":200},{"vni":300,"vniEnd":399}]}]
+    #
+    # Example output: ['10010', '10020', '10021', '10022']
+    os_configured_vnis = []
+    tmp = loads(cmd(f'bridge --json vni show dev {interface}'))
+    if tmp:
+        for tunnel in tmp[0].get('vnis', {}):
+            vniStart = tunnel['vni']
+            if 'vniEnd' in tunnel:
+                vniEnd = tunnel['vniEnd']
+                # Build a real list for user VNIs
+                vni_list = list(range(vniStart, vniEnd +1))
+                # Convert list of integers to list or strings
+                os_configured_vnis.extend(map(str, vni_list))
+                # Proceed with next tunnel - this one is complete
+                continue
+
+            # Add single tunel id - not part of a range
+            os_configured_vnis.append(str(vniStart))
+
+    return os_configured_vnis