tools: ynl: support packing binary arrays of scalars

We support decoding a binary type with a scalar subtype already,
add support for sending such arrays to the kernel. While at it
also support using "None" to indicate that the binary attribute
should be empty. I couldn't decide whether empty binary should
be [] or None, but there should be no harm in supporting both.

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

tools/net/ynl/pyynl/lib/ynl.py

@@ -575,7 +575,9 @@ def _add_attr(self, space, name, value, search_attrs):
         elif attr["type"] == 'string':
             attr_payload = str(value).encode('ascii') + b'\x00'
         elif attr["type"] == 'binary':
-            if isinstance(value, bytes):
+            if value is None:
+                attr_payload = b''
+            elif isinstance(value, bytes):
                 attr_payload = value
             elif isinstance(value, str):
                 if attr.display_hint:
@@ -584,6 +586,9 @@ def _add_attr(self, space, name, value, search_attrs):
                     attr_payload = bytes.fromhex(value)
             elif isinstance(value, dict) and attr.struct_name:
                 attr_payload = self._encode_struct(attr.struct_name, value)
+            elif isinstance(value, list) and attr.sub_type in NlAttr.type_formats:
+                format = NlAttr.get_format(attr.sub_type)
+                attr_payload = b''.join([format.pack(x) for x in value])
             else:
                 raise Exception(f'Unknown type for binary attribute, value: {value}')
         elif attr['type'] in NlAttr.type_formats or attr.is_auto_scalar: