[PATCH net-next v3 4/6] tools/net/ynl: Add nest-type-value decoding

[Donald Hunter <donald.hunter@gmail.com>]

The nlctrl genetlink-legacy family uses nest-type-value encoding as
described in Documentation/userspace-api/netlink/genetlink-legacy.rst

Add nest-type-value decoding to ynl.

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
---
 tools/net/ynl/lib/ynl.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
index b810a478a304..2d7fdd903d9e 100644
--- a/tools/net/ynl/lib/ynl.py
+++ b/tools/net/ynl/lib/ynl.py
@@ -595,6 +595,16 @@ class YnlFamily(SpecFamily):
             decoded.append({ item.type: subattrs })
         return decoded
 
+    def _decode_nest_type_value(self, attr, attr_spec):
+        decoded = {}
+        value = attr
+        for name in attr_spec['type-value']:
+            value = NlAttr(value.raw, 0)
+            decoded[name] = value.type
+        subattrs = self._decode(NlAttrs(value.raw), attr_spec['nested-attributes'])
+        decoded.update(subattrs)
+        return decoded
+
     def _decode_unknown(self, attr):
         if attr.is_nest:
             return self._decode(NlAttrs(attr.raw), None)
@@ -686,6 +696,8 @@ class YnlFamily(SpecFamily):
                 decoded = {"value": value, "selector": selector}
             elif attr_spec["type"] == 'sub-message':
                 decoded = self._decode_sub_msg(attr, attr_spec, search_attrs)
+            elif attr_spec["type"] == 'nest-type-value':
+                decoded = self._decode_nest_type_value(attr, attr_spec)
             else:
                 if not self.process_unknown:
                     raise Exception(f'Unknown {attr_spec["type"]} with name {attr_spec["name"]}')
-- 
2.42.0