vxlan: T3700: support VLAN tunnel mapping of VLAN aware bridges

FRR supports a new way of configuring VLAN-to-VNI mappings for EVPN-VXLAN, when
working with the Linux kernel. In this new way, the mapping of a VLAN to a VNI
is configured against a container VXLAN interface which is referred to as a
'Single VXLAN device (SVD)'.

Multiple VLAN to VNI mappings can be configured against the same SVD. This
allows for a significant scaling of the number of VNIs since a separate VXLAN
interface is no longer required for each VNI.

Sample configuration of SVD with VLAN to VNI mappings is shown below.

set interfaces bridge br0 member interface vxlan0
set interfaces vxlan vxlan0 external
set interfaces vxlan vxlan0 source-interface 'dum0'
set interfaces vxlan vxlan0 vlan-to-vni 10 vni '10010'
set interfaces vxlan vxlan0 vlan-to-vni 11 vni '10011'
set interfaces vxlan vxlan0 vlan-to-vni 30 vni '10030'
set interfaces vxlan vxlan0 vlan-to-vni 31 vni '10031'

(cherry picked from commit 7f6624f5a6f8bd1749b54103ea5ec9f010adf778)

2 files changed, 45 insertions, 2 deletions

diff --git a/python/vyos/utils/network.py b/python/vyos/utils/network.py
index bc6899e45..c96ee4eed 100644
--- a/python/vyos/utils/network.py
+++ b/python/vyos/utils/network.py
@@ -429,7 +429,7 @@ def is_subnet_connected(subnet, primary=False):
 
     return False
 
-def is_afi_configured(interface, afi):
+def is_afi_configured(interface: str, afi):
     """ Check if given address family is configured, or in other words - an IP
     address is assigned to the interface. """
     from netifaces import ifaddresses
@@ -446,3 +446,46 @@ def is_afi_configured(interface, afi):
         return False
 
     return afi in addresses
+
+def get_vxlan_vlan_tunnels(interface: str) -> list:
+    """ Return a list of strings with VLAN IDs 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 VLANs
+    #
+    # $ bridge -j -p vlan tunnelshow dev vxlan0
+    # [ {
+    #         "ifname": "vxlan0",
+    #         "tunnels": [ {
+    #                 "vlan": 10,
+    #                 "vlanEnd": 11,
+    #                 "tunid": 10010,
+    #                 "tunidEnd": 10011
+    #             },{
+    #                 "vlan": 20,
+    #                 "tunid": 10020
+    #             } ]
+    #     } ]
+    #
+    os_configured_vlan_ids = []
+    tmp = loads(cmd(f'bridge --json vlan tunnelshow dev {interface}'))
+    if tmp:
+        for tunnel in tmp[0].get('tunnels', {}):
+            vlanStart = tunnel['vlan']
+            if 'vlanEnd' in tunnel:
+                vlanEnd = tunnel['vlanEnd']
+                # Build a real list for user VLAN IDs
+                vlan_list = list(range(vlanStart, vlanEnd +1))
+                # Convert list of integers to list or strings
+                os_configured_vlan_ids.extend(map(str, vlan_list))
+                # Proceed with next tunnel - this one is complete
+                continue
+
+            # Add single tunel id - not part of a range
+            os_configured_vlan_ids.append(str(vlanStart))
+
+    return os_configured_vlan_ids
diff --git a/python/vyos/utils/process.py b/python/vyos/utils/process.py
index e09c7d86d..1c861815e 100644
--- a/python/vyos/utils/process.py
+++ b/python/vyos/utils/process.py
@@ -139,7 +139,7 @@ def cmd(command, flag='', shell=None, input=None, timeout=None, env=None,
     expect:  a list of error codes to consider as normal
     """
     decoded, code = popen(
-        command, flag,
+        command.lstrip(), flag,
         stdout=stdout, stderr=stderr,
         input=input, timeout=timeout,
         env=env, shell=shell,