[patch net-next v4] tools: ynl: introduce option to process unknown attributes or types

[patch net-next v4] tools: ynl: introduce option to process unknown attributes or types

[Jiri Pirko]

From: Jiri Pirko <jiri@nvidia.com>

In case the kernel sends message back containing attribute not defined
in family spec, following exception is raised to the user:

$ sudo ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/devlink.yaml --do trap-get --json '{"bus-name": "netdevsim", "dev-name": "netdevsim1", "trap-name": "source_mac_is_multicast"}'
Traceback (most recent call last):
  File "/home/jiri/work/linux/tools/net/ynl/lib/ynl.py", line 521, in _decode
    attr_spec = attr_space.attrs_by_val[attr.type]
                ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
KeyError: 132

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jiri/work/linux/./tools/net/ynl/cli.py", line 61, in <module>
    main()
  File "/home/jiri/work/linux/./tools/net/ynl/cli.py", line 49, in main
    reply = ynl.do(args.do, attrs, args.flags)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jiri/work/linux/tools/net/ynl/lib/ynl.py", line 731, in do
    return self._op(method, vals, flags)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jiri/work/linux/tools/net/ynl/lib/ynl.py", line 719, in _op
    rsp_msg = self._decode(decoded.raw_attrs, op.attr_set.name)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jiri/work/linux/tools/net/ynl/lib/ynl.py", line 525, in _decode
    raise Exception(f"Space '{space}' has no attribute with value '{attr.type}'")
Exception: Space 'devlink' has no attribute with value '132'

Introduce a command line option "process-unknown" and pass it down to
YnlFamily class constructor to allow user to process unknown
attributes and types and print them as binaries.

$ sudo ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/devlink.yaml --do trap-get --json '{"bus-name": "netdevsim", "dev-name": "netdevsim1", "trap-name": "source_mac_is_multicast"}' --process-unknown
{'UnknownAttr(129)': {'UnknownAttr(0)': b'\x00\x00\x00\x00\x00\x00\x00\x00',
                      'UnknownAttr(1)': b'\x00\x00\x00\x00\x00\x00\x00\x00',
                      'UnknownAttr(2)': b'\x0e\x00\x00\x00\x00\x00\x00\x00'},
 'UnknownAttr(132)': b'\x00',
 'UnknownAttr(133)': b'',
 'UnknownAttr(134)': {'UnknownAttr(0)': b''},
 'bus-name': 'netdevsim',
 'dev-name': 'netdevsim1',
 'trap-action': 'drop',
 'trap-group-name': 'l2_drops',
 'trap-name': 'source_mac_is_multicast'}

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
v3->v4:
- changed unknown attr key to f"UnknownAttr({attr.type})"
v2->v3:
- rebased on top of previous patchset and recent net-next
- removed fake attr spec class
- introduced "attr.is_nest" and using it instead of direct access
  to "attr._type"
- pushed out rsp value addition into separate helper and sanitize
  the unknown attr is possibly multi-value there
- pushed out unknown attr decode into separate helper
v1->v2:
- changed to process unknown attributes and type instead of ignoring them
---
 tools/net/ynl/cli.py     |  3 ++-
 tools/net/ynl/lib/ynl.py | 48 +++++++++++++++++++++++++++++++---------
 2 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/tools/net/ynl/cli.py b/tools/net/ynl/cli.py
index 564ecf07cd2c..2ad9ec0f5545 100755
--- a/tools/net/ynl/cli.py
+++ b/tools/net/ynl/cli.py
@@ -27,6 +27,7 @@ def main():
                         const=Netlink.NLM_F_CREATE)
     parser.add_argument('--append', dest='flags', action='append_const',
                         const=Netlink.NLM_F_APPEND)
+    parser.add_argument('--process-unknown', action=argparse.BooleanOptionalAction)
     args = parser.parse_args()
 
     if args.no_schema:
@@ -36,7 +37,7 @@ def main():
     if args.json_text:
         attrs = json.loads(args.json_text)
 
-    ynl = YnlFamily(args.spec, args.schema)
+    ynl = YnlFamily(args.spec, args.schema, args.process_unknown)
 
     if args.ntf:
         ynl.ntf_subscribe(args.ntf)
diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
index b1da4aea9336..92995bca14e1 100644
--- a/tools/net/ynl/lib/ynl.py
+++ b/tools/net/ynl/lib/ynl.py
@@ -100,6 +100,7 @@ class NlAttr:
     def __init__(self, raw, offset):
         self._len, self._type = struct.unpack("HH", raw[offset:offset + 4])
         self.type = self._type & ~Netlink.NLA_TYPE_MASK
+        self.is_nest = self._type & Netlink.NLA_F_NESTED
         self.payload_len = self._len
         self.full_len = (self.payload_len + 3) & ~3
         self.raw = raw[offset + 4:offset + self.payload_len]
@@ -411,10 +412,11 @@ class GenlProtocol(NetlinkProtocol):
 
 
 class YnlFamily(SpecFamily):
-    def __init__(self, def_path, schema=None):
+    def __init__(self, def_path, schema=None, process_unknown=False):
         super().__init__(def_path, schema)
 
         self.include_raw = False
+        self.process_unknown = process_unknown
 
         try:
             if self.proto == "netlink-raw":
@@ -526,14 +528,41 @@ class YnlFamily(SpecFamily):
             decoded.append({ item.type: subattrs })
         return decoded
 
+    def _decode_unknown(self, attr):
+        if attr.is_nest:
+            return self._decode(NlAttrs(attr.raw), None)
+        else:
+            return attr.as_bin()
+
+    def _rsp_add(self, rsp, name, is_multi, decoded):
+        if is_multi == None:
+            if name in rsp and type(rsp[name]) is not list:
+                rsp[name] = [rsp[name]]
+                is_multi = True
+            else:
+                is_multi = False
+
+        if not is_multi:
+            rsp[name] = decoded
+        elif name in rsp:
+            rsp[name].append(decoded)
+        else:
+            rsp[name] = [decoded]
+
     def _decode(self, attrs, space):
-        attr_space = self.attr_sets[space]
+        if space:
+            attr_space = self.attr_sets[space]
         rsp = dict()
         for attr in attrs:
             try:
                 attr_spec = attr_space.attrs_by_val[attr.type]
-            except KeyError:
-                raise Exception(f"Space '{space}' has no attribute with value '{attr.type}'")
+            except (KeyError, UnboundLocalError):
+                if not self.process_unknown:
+                    raise Exception(f"Space '{space}' has no attribute with value '{attr.type}'")
+                attr_name = f"UnknownAttr({attr.type})"
+                self._rsp_add(rsp, attr_name, None, self._decode_unknown(attr))
+                continue
+
             if attr_spec["type"] == 'nest':
                 subdict = self._decode(NlAttrs(attr.raw), attr_spec['nested-attributes'])
                 decoded = subdict
@@ -558,14 +587,11 @@ class YnlFamily(SpecFamily):
                     selector = self._decode_enum(selector, attr_spec)
                 decoded = {"value": value, "selector": selector}
             else:
-                raise Exception(f'Unknown {attr_spec["type"]} with name {attr_spec["name"]}')
+                if not self.process_unknown:
+                    raise Exception(f'Unknown {attr_spec["type"]} with name {attr_spec["name"]}')
+                decoded = self._decode_unknown(attr)
 
-            if not attr_spec.is_multi:
-                rsp[attr_spec['name']] = decoded
-            elif attr_spec.name in rsp:
-                rsp[attr_spec.name].append(decoded)
-            else:
-                rsp[attr_spec.name] = [decoded]
+            self._rsp_add(rsp, attr_spec["name"], attr_spec.is_multi, decoded)
 
         return rsp
 
-- 
2.41.0

Re: [patch net-next v4] tools: ynl: introduce option to process unknown attributes or types

[Jakub Kicinski]

On Fri, 27 Oct 2023 11:25:25 +0200 Jiri Pirko wrote:
> - changed unknown attr key to f"UnknownAttr({attr.type})"

Not what I wanted but okay. Let's move on.. :)

Re: [patch net-next v4] tools: ynl: introduce option to process unknown attributes or types

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 27 Oct 2023 11:25:25 +0200 you wrote:
> From: Jiri Pirko <jiri@nvidia.com>
> 
> In case the kernel sends message back containing attribute not defined
> in family spec, following exception is raised to the user:
> 
> $ sudo ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/devlink.yaml --do trap-get --json '{"bus-name": "netdevsim", "dev-name": "netdevsim1", "trap-name": "source_mac_is_multicast"}'
> Traceback (most recent call last):
>   File "/home/jiri/work/linux/tools/net/ynl/lib/ynl.py", line 521, in _decode
>     attr_spec = attr_space.attrs_by_val[attr.type]
>                 ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
> KeyError: 132
> 
> [...]

Here is the summary with links:
  - [net-next,v4] tools: ynl: introduce option to process unknown attributes or types
    https://git.kernel.org/netdev/net-next/c/d96e48a3d55d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [patch net-next v4] tools: ynl: introduce option to process unknown attributes or types

[Jiri Pirko]

Fri, Oct 27, 2023 at 11:54:19PM CEST, kuba@kernel.org wrote:
>On Fri, 27 Oct 2023 11:25:25 +0200 Jiri Pirko wrote:
>> - changed unknown attr key to f"UnknownAttr({attr.type})"
>
>Not what I wanted but okay. Let's move on.. :)

Feel free to patch the way you wanted. But I don't see any nicer way
now. What you suggest with the class does not make sense to me.