On Sat, 18 Mar 2023 at 04:50, Jakub Kicinski [off-list ref] wrote:

On Thu, 16 Mar 2023 12:01:41 +0000 Donald Hunter wrote:

quoted

Subject: [PATCH net-next v1 1/2] tools: ynl: add user-header and struct attr support

The use of "and" usually indicates it should be 2 separate patches ;)

Ack. I'll try and split it into two.

quoted

+  user-header:
+    description: Name of the struct definition for the user header for the family.
+    type: string

Took me a minute to remember this is header as in protocol header
not header as in C header file :) Would it possibly be better to call it
fixed-header ? Can't really decide myself.

I went with user header because the generic netlink howto calls it the
"optional user specific message header" but happy to go with fixed-header.

But the description definitely need to be more verbose:

description: |
  Name of the structure defining the fixed-length protocol header.
  This header is placed in a message after the netlink and genetlink
  headers and before any attributes.

Agreed, this is a much clearer description.

quoted

+    def as_array(self, type):
+        format, _ = self.type_formats[type]
+        return list({ x[0] for x in struct.iter_unpack(format, self.raw) })

The Python is strong within you :)

quoted

+    def as_struct(self, members):
+        value = dict()
+        offset = 0
+        for m in members:
+            type = m['type']

Accessing the spec components directly is a bit of an anti-pattern,
can we parse the struct description into Python objects in
tools/net/ynl/lib/nlspec.py ?

Ack, will do.

quoted

+            format, size = self.type_formats[type]
+            decoded = struct.unpack_from(format, self.raw, offset)
+            offset += size
+            value[m['name']] = decoded[0]
+        return value
+
     def __repr__(self):
         return f"[type:{self.type} len:{self._len}] {self.raw}"

@@ -200,7 +220,7 @@ def _genl_msg(nl_type, nl_flags, genl_cmd, genl_version, seq=None):
     if seq is None:
         seq = random.randint(1, 1024)
     nlmsg = struct.pack("HHII", nl_type, nl_flags, seq, 0)
-    genlmsg = struct.pack("bbH", genl_cmd, genl_version, 0)
+    genlmsg = struct.pack("BBH", genl_cmd, genl_version, 0)

Should also be a separate patch

Yep, I will separate this into its own patch.

quoted

     return nlmsg + genlmsg

@@ -258,14 +278,22 @@ def _genl_load_families():


 class GenlMsg:
-    def __init__(self, nl_msg):
+    def __init__(self, nl_msg, extra_headers = []):
         self.nl = nl_msg

         self.hdr = nl_msg.raw[0:4]
-        self.raw = nl_msg.raw[4:]
+        offset = 4

-        self.genl_cmd, self.genl_version, _ = struct.unpack("bbH", self.hdr)
+        self.genl_cmd, self.genl_version, _ = struct.unpack("BBH", self.hdr)

+        self.user_attrs = dict()
+        for m in extra_headers:
+            format, size = NlAttr.type_formats[m['type']]
+            decoded = struct.unpack_from(format, nl_msg.raw, offset)
+            offset += size
+            self.user_attrs[m['name']] = decoded[0]

user_attrs?

Um, attrs of the user-header. I'll try to name this better.

quoted

+        self.raw = nl_msg.raw[offset:]
         self.raw_attrs = NlAttrs(self.raw)

     def __repr__(self):

@@ -315,6 +343,7 @@ class YnlFamily(SpecFamily):
             setattr(self, op.ident_name, bound_f)

         self.family = GenlFamily(self.yaml['name'])
+        self._user_header = self.yaml.get('user-header', None)

     def ntf_subscribe(self, mcast_name):
         if mcast_name not in self.family.genl_family['mcast']:

@@ -358,7 +387,7 @@ class YnlFamily(SpecFamily):
                 raw >>= 1
                 i += 1
         else:
-            value = enum['entries'][raw - i]
+            value = enum.entries_by_val[raw - i]['name']

Also a separate fix :S

Ack, will do.