Merge branch 'tools-ynl-byteorder'

Donald Hunter says:

====================
tools: ynl: Add byte-order support for struct members

This patchset adds support to ynl for handling byte-order in struct
members. The first patch is a refactor to use predefined Struct() objects
instead of generating byte-order specific formats on the fly. The second
patch adds byte-order handling for struct members.
====================
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/netlink/genetlink-legacy.yaml

@@ -122,6 +122,8 @@ properties:
                 enum: [ u8, u16, u32, u64, s8, s16, s32, s64, string ]
               len:
                 $ref: '#/$defs/len-or-define'
+              byte-order:
+                enum: [ little-endian, big-endian ]
         # End genetlink-legacy
 
   attribute-sets:

tools/net/ynl/lib/nlspec.py

@@ -226,11 +226,13 @@ class SpecStructMember(SpecElement):
     Represents a single struct member attribute.
 
     Attributes:
-        type    string, type of the member attribute
+        type        string, type of the member attribute
+        byte_order  string or None for native byte order
     """
     def __init__(self, family, yaml):
         super().__init__(family, yaml)
         self.type = yaml['type']
+        self.byte_order = yaml.get('byte-order')
 
 
 class SpecStruct(SpecElement):

tools/net/ynl/lib/ynl.py

 # SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
 
+from collections import namedtuple
 import functools
 import os
 import random
 import socket
 import struct
+from struct import Struct
 import yaml
 
 from .nlspec import SpecFamily
@@ -76,10 +78,17 @@ class NlError(Exception):
 
 
 class NlAttr:
-    type_formats = { 'u8' : ('B', 1), 's8' : ('b', 1),
-                     'u16': ('H', 2), 's16': ('h', 2),
-                     'u32': ('I', 4), 's32': ('i', 4),
-                     'u64': ('Q', 8), 's64': ('q', 8) }
+    ScalarFormat = namedtuple('ScalarFormat', ['native', 'big', 'little'])
+    type_formats = {
+        'u8' : ScalarFormat(Struct('B'), Struct("B"),  Struct("B")),
+        's8' : ScalarFormat(Struct('b'), Struct("b"),  Struct("b")),
+        'u16': ScalarFormat(Struct('H'), Struct(">H"), Struct("<H")),
+        's16': ScalarFormat(Struct('h'), Struct(">h"), Struct("<h")),
+        'u32': ScalarFormat(Struct('I'), Struct(">I"), Struct("<I")),
+        's32': ScalarFormat(Struct('i'), Struct(">i"), Struct("<i")),
+        'u64': ScalarFormat(Struct('Q'), Struct(">Q"), Struct("<Q")),
+        's64': ScalarFormat(Struct('q'), Struct(">q"), Struct("<q"))
+    }
 
     def __init__(self, raw, offset):
         self._len, self._type = struct.unpack("HH", raw[offset:offset + 4])
@@ -88,25 +97,17 @@ class NlAttr:
         self.full_len = (self.payload_len + 3) & ~3
         self.raw = raw[offset + 4:offset + self.payload_len]
 
-    def format_byte_order(byte_order):
+    @classmethod
+    def get_format(cls, attr_type, byte_order=None):
+        format = cls.type_formats[attr_type]
         if byte_order:
-            return ">" if byte_order == "big-endian" else "<"
-        return ""
+            return format.big if byte_order == "big-endian" \
+                else format.little
+        return format.native
 
-    def as_u8(self):
-        return struct.unpack("B", self.raw)[0]
-
-    def as_u16(self, byte_order=None):
-        endian = NlAttr.format_byte_order(byte_order)
-        return struct.unpack(f"{endian}H", self.raw)[0]
-
-    def as_u32(self, byte_order=None):
-        endian = NlAttr.format_byte_order(byte_order)
-        return struct.unpack(f"{endian}I", self.raw)[0]
-
-    def as_u64(self, byte_order=None):
-        endian = NlAttr.format_byte_order(byte_order)
-        return struct.unpack(f"{endian}Q", self.raw)[0]
+    def as_scalar(self, attr_type, byte_order=None):
+        format = self.get_format(attr_type, byte_order)
+        return format.unpack(self.raw)[0]
 
     def as_strz(self):
         return self.raw.decode('ascii')[:-1]
@@ -115,17 +116,17 @@ class NlAttr:
         return self.raw
 
     def as_c_array(self, type):
-        format, _ = self.type_formats[type]
-        return list({ x[0] for x in struct.iter_unpack(format, self.raw) })
+        format = self.get_format(type)
+        return [ x[0] for x in format.iter_unpack(self.raw) ]
 
     def as_struct(self, members):
         value = dict()
         offset = 0
         for m in members:
             # TODO: handle non-scalar members
-            format, size = self.type_formats[m.type]
-            decoded = struct.unpack_from(format, self.raw, offset)
-            offset += size
+            format = self.get_format(m.type, m.byte_order)
+            decoded = format.unpack_from(self.raw, offset)
+            offset += format.size
             value[m.name] = decoded[0]
         return value
 
@@ -184,11 +185,11 @@ class NlMsg:
                 if extack.type == Netlink.NLMSGERR_ATTR_MSG:
                     self.extack['msg'] = extack.as_strz()
                 elif extack.type == Netlink.NLMSGERR_ATTR_MISS_TYPE:
-                    self.extack['miss-type'] = extack.as_u32()
+                    self.extack['miss-type'] = extack.as_scalar('u32')
                 elif extack.type == Netlink.NLMSGERR_ATTR_MISS_NEST:
-                    self.extack['miss-nest'] = extack.as_u32()
+                    self.extack['miss-nest'] = extack.as_scalar('u32')
                 elif extack.type == Netlink.NLMSGERR_ATTR_OFFS:
-                    self.extack['bad-attr-offs'] = extack.as_u32()
+                    self.extack['bad-attr-offs'] = extack.as_scalar('u32')
                 else:
                     if 'unknown' not in self.extack:
                         self.extack['unknown'] = []
@@ -272,11 +273,11 @@ def _genl_load_families():
                 fam = dict()
                 for attr in gm.raw_attrs:
                     if attr.type == Netlink.CTRL_ATTR_FAMILY_ID:
-                        fam['id'] = attr.as_u16()
+                        fam['id'] = attr.as_scalar('u16')
                     elif attr.type == Netlink.CTRL_ATTR_FAMILY_NAME:
                         fam['name'] = attr.as_strz()
                     elif attr.type == Netlink.CTRL_ATTR_MAXATTR:
-                        fam['maxattr'] = attr.as_u32()
+                        fam['maxattr'] = attr.as_scalar('u32')
                     elif attr.type == Netlink.CTRL_ATTR_MCAST_GROUPS:
                         fam['mcast'] = dict()
                         for entry in NlAttrs(attr.raw):
@@ -286,7 +287,7 @@ def _genl_load_families():
                                 if entry_attr.type == Netlink.CTRL_ATTR_MCAST_GRP_NAME:
                                     mcast_name = entry_attr.as_strz()
                                 elif entry_attr.type == Netlink.CTRL_ATTR_MCAST_GRP_ID:
-                                    mcast_id = entry_attr.as_u32()
+                                    mcast_id = entry_attr.as_scalar('u32')
                             if mcast_name and mcast_id is not None:
                                 fam['mcast'][mcast_name] = mcast_id
                 if 'name' in fam and 'id' in fam:
@@ -304,9 +305,9 @@ class GenlMsg:
 
         self.fixed_header_attrs = dict()
         for m in fixed_header_members:
-            format, size = NlAttr.type_formats[m.type]
-            decoded = struct.unpack_from(format, nl_msg.raw, offset)
-            offset += size
+            format = NlAttr.get_format(m.type, m.byte_order)
+            decoded = format.unpack_from(nl_msg.raw, offset)
+            offset += format.size
             self.fixed_header_attrs[m.name] = decoded[0]
 
         self.raw = nl_msg.raw[offset:]
@@ -381,21 +382,13 @@ class YnlFamily(SpecFamily):
                 attr_payload += self._add_attr(attr['nested-attributes'], subname, subvalue)
         elif attr["type"] == 'flag':
             attr_payload = b''
-        elif attr["type"] == 'u8':
-            attr_payload = struct.pack("B", int(value))
-        elif attr["type"] == 'u16':
-            endian = NlAttr.format_byte_order(attr.byte_order)
-            attr_payload = struct.pack(f"{endian}H", int(value))
-        elif attr["type"] == 'u32':
-            endian = NlAttr.format_byte_order(attr.byte_order)
-            attr_payload = struct.pack(f"{endian}I", int(value))
-        elif attr["type"] == 'u64':
-            endian = NlAttr.format_byte_order(attr.byte_order)
-            attr_payload = struct.pack(f"{endian}Q", int(value))
         elif attr["type"] == 'string':
             attr_payload = str(value).encode('ascii') + b'\x00'
         elif attr["type"] == 'binary':
             attr_payload = value
+        elif attr['type'] in NlAttr.type_formats:
+            format = NlAttr.get_format(attr['type'], attr.byte_order)
+            attr_payload = format.pack(int(value))
         else:
             raise Exception(f'Unknown type at {space} {name} {value} {attr["type"]}')
 
@@ -434,22 +427,16 @@ class YnlFamily(SpecFamily):
             if attr_spec["type"] == 'nest':
                 subdict = self._decode(NlAttrs(attr.raw), attr_spec['nested-attributes'])
                 decoded = subdict
-            elif attr_spec['type'] == 'u8':
-                decoded = attr.as_u8()
-            elif attr_spec['type'] == 'u16':
-                decoded = attr.as_u16(attr_spec.byte_order)
-            elif attr_spec['type'] == 'u32':
-                decoded = attr.as_u32(attr_spec.byte_order)
-            elif attr_spec['type'] == 'u64':
-                decoded = attr.as_u64(attr_spec.byte_order)
             elif attr_spec["type"] == 'string':
                 decoded = attr.as_strz()
             elif attr_spec["type"] == 'binary':
                 decoded = self._decode_binary(attr, attr_spec)
             elif attr_spec["type"] == 'flag':
                 decoded = True
+            elif attr_spec["type"] in NlAttr.type_formats:
+                decoded = attr.as_scalar(attr_spec['type'], attr_spec.byte_order)
             else:
-                raise Exception(f'Unknown {attr.type} {attr_spec["name"]} {attr_spec["type"]}')
+                raise Exception(f'Unknown {attr_spec["type"]} with name {attr_spec["name"]}')
 
             if not attr_spec.is_multi:
                 rsp[attr_spec['name']] = decoded
@@ -555,8 +542,8 @@ class YnlFamily(SpecFamily):
             fixed_header_members = self.consts[op.fixed_header].members
             for m in fixed_header_members:
                 value = vals.pop(m.name)
-                format, _ = NlAttr.type_formats[m.type]
-                msg += struct.pack(format, value)
+                format = NlAttr.get_format(m.type, m.byte_order)
+                msg += format.pack(value)
         for name, value in vals.items():
             msg += self._add_attr(op.attr_set.name, name, value)
         msg = _genl_msg_finalize(msg)