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Date: Fri, 17 Mar 2023 21:50:38 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Donald Hunter <donald.hunter@...il.com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>, donald.hunter@...hat.com
Subject: Re: [PATCH net-next v1 1/2] tools: ynl: add user-header and struct
attr support
On Thu, 16 Mar 2023 12:01:41 +0000 Donald Hunter wrote:
> 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 ;)
> Signed-off-by: Donald Hunter <donald.hunter@...il.com>
> ---
> 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
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.
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.
> # 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) })
The Python is strong within you :)
> + 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 ?
> + 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
> 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?
> + 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
> 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
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