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

From: Donald Hunter <[email-masked]>
Date: Thu, 16 Mar 2023 12:01:41 +0000

Signed-off-by: Donald Hunter <[email-masked]>
---
 Documentation/netlink/genetlink-legacy.yaml | 10 +++-
 tools/net/ynl/lib/ynl.py                    | 58 ++++++++++++++++++---
 2 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/Documentation/netlink/genetlink-legacy.yaml b/Documentation/netlink/genetlink-legacy.yaml
index c6b8c77f7d12..7f019c0a9762 100644
--- a/Documentation/netlink/genetlink-legacy.yaml
+++ b/Documentation/netlink/genetlink-legacy.yaml
@@ -53,6 +53,9 @@ properties:
       Defines if the input policy in the kernel is global, per-operation, or split per operation type.
       Default is split.
     enum: [ split, per-op, global ]
+  user-header:
+    description: Name of the struct definition for the user header for the family.
+    type: string
   # End genetlink-legacy
 
   definitions:
@@ -172,7 +175,7 @@ properties:
                 type: string
               type: &attr-type
                 enum: [ unused, pad, flag, binary, u8, u16, u32, u64, s32, s64,
-                        string, nest, array-nest, nest-type-value ]
+                        string, nest, array-nest, nest-type-value, struct ]
               doc:
                 description: Documentation of the attribute.
                 type: string
@@ -218,6 +221,11 @@ properties:
                     description: Max length for a string or a binary attribute.
                     $ref: '#/$defs/len-or-define'
               sub-type: *attr-type
+              # Start genetlink-legacy
+              struct:
+                description: Name of the struct type used for the attribute.
+                type: string
+              # End genetlink-legacy
 
       # Make sure name-prefix does not appear in subsets (subsets inherit naming)
       dependencies:
diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
index 90764a83c646..584b1e0a6b2f 100644
--- a/tools/net/ynl/lib/ynl.py
+++ b/tools/net/ynl/lib/ynl.py
@@ -68,6 +68,11 @@ class Netlink:

 class NlAttr:
+    type_formats = { 'u8' : ('B', 1),
+                     'u16': ('H', 2),
+                     'u32': ('I', 4),
+                     'u64': ('Q', 8) }
+
     def __init__(self, raw, offset):
         self._len, self._type = struct.unpack("HH", raw[offset:offset + 4])
         self.type = self._type & ~Netlink.NLA_TYPE_MASK
@@ -93,6 +98,21 @@ class NlAttr:
     def as_bin(self):
         return self.raw
 
+    def as_array(self, type):
+        format, _ = self.type_formats[type]
+        return list({ x[0] for x in struct.iter_unpack(format, self.raw) })
+
+    def as_struct(self, members):
+        value = dict()
+        offset = 0
+        for m in members:
+            type = m['type']
+            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)
     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]
+
+        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']
         rsp[attr_spec['name']] = value
 
     def _decode(self, attrs, space):
@@ -381,6 +410,14 @@ class YnlFamily(SpecFamily):
                 decoded = attr.as_bin()
             elif attr_spec["type"] == 'flag':
                 decoded = True
+            elif attr_spec["type"] == 'struct':
+                s = attr_spec['struct']
+                decoded = attr.as_struct(self.consts[s]['members'])
+            elif attr_spec["type"] == 'array-nest':
+                decoded = attr.as_array(attr_spec["sub-type"])
+            elif attr_spec["type"] == 'unused':
+                print(f"Warning: skipping unused attribute {attr_spec['name']}")
+                continue
             else:
                 raise Exception(f'Unknown {attr.type} {attr_spec["name"]} {attr_spec["type"]}')
 
@@ -472,6 +509,13 @@ class YnlFamily(SpecFamily):
 
         req_seq = random.randint(1024, 65535)
         msg = _genl_msg(self.family.family_id, nl_flags, op.req_value, 1, req_seq)
+        user_headers = []
+        if self._user_header:
+            user_headers = self.consts[self._user_header]['members']
+            for m in user_headers:
+                value = vals.pop(m['name'])
+                format, _ = NlAttr.type_formats[m['type']]
+                msg += struct.pack(format, value)
         for name, value in vals.items():
             msg += self._add_attr(op.attr_set.name, name, value)
         msg = _genl_msg_finalize(msg)
@@ -498,7 +542,7 @@ class YnlFamily(SpecFamily):
                     done = True
                     break
 
-                gm = GenlMsg(nl_msg)
+                gm = GenlMsg(nl_msg, user_headers)
                 # Check if this is a reply to our request
                 if nl_msg.nl_seq != req_seq or gm.genl_cmd != op.rsp_value:
                     if gm.genl_cmd in self.async_msg_ids:
@@ -508,7 +552,7 @@ class YnlFamily(SpecFamily):
                         print('Unexpected message: ' + repr(gm))
                         continue
 
-                rsp.append(self._decode(gm.raw_attrs, op.attr_set.name))
+                rsp.append(self._decode(gm.raw_attrs, op.attr_set.name) | gm.user_attrs)
 
         if not rsp:
             return None
-- 
2.39.0