T4630: can not use same source-interface for macsec and pseudo-ethernet

A macsec interface requires a dedicated source interface, it can not be
shared with another macsec or a pseudo-ethernet interface.

set interfaces macsec macsec10 address '192.168.2.1/30'
set interfaces macsec macsec10 security cipher 'gcm-aes-256'
set interfaces macsec macsec10 security encrypt
set interfaces macsec macsec10 security mka cak '232e44b7fda6f8e2d88a07bf78a7aff4232e44b7fda6f8e2d88a07bf78a7aff4'
set interfaces macsec macsec10 security mka ckn '09924585a6f3010208cf5222ef24c821405b0e34f4b4f63b1f0ced474b9bb6e6'
set interfaces macsec macsec10 source-interface 'eth1'
commit

set interfaces pseudo-ethernet peth0 source-interface eth1
commit

Reuslts in

FileNotFoundError: [Errno 2] failed to run command: ip link add peth0 link eth1 type macvlan mode private
returned:
exit code: 2

noteworthy:
cmd 'ip link add peth0 link eth1 type macvlan mode private'
returned (out):

returned (err):
RTNETLINK answers: Device or resource busy

[[interfaces pseudo-ethernet peth0]] failed
Commit failed

1 files changed, 9 insertions, 2 deletions

diff --git a/python/vyos/configdict.py b/python/vyos/configdict.py
index 8f822a97d..912bc94f2 100644
--- a/python/vyos/configdict.py
+++ b/python/vyos/configdict.py
@@ -295,11 +295,18 @@ def is_source_interface(conf, interface, intftype=None):
     """
     ret_val = None
     intftypes = ['macsec', 'pppoe', 'pseudo-ethernet', 'tunnel', 'vxlan']
-    if intftype not in intftypes + [None]:
+    if not intftype:
+        intftype = intftypes
+
+    if isinstance(intftype, str):
+        intftype = [intftype]
+    elif not isinstance(intftype, list):
+        raise ValueError(f'Interface type "{type(intftype)}" must be either str or list!')
+
+    if not all(x in intftypes for x in intftype):
         raise ValueError(f'unknown interface type "{intftype}" or it can not '
             'have a source-interface')
 
-    intftype = intftypes if intftype == None else [intftype]
     for it in intftype:
         base = ['interfaces', it]
         for intf in conf.list_nodes(base):