1 files changed, 1091 insertions, 0 deletions
diff --git a/tools/net/ynl/pyynl/lib/ynl.py b/tools/net/ynl/pyynl/lib/ynl.py
new file mode 100644
index 000000000000..dcc2c6b298d6
--- /dev/null
+++ b/tools/net/ynl/pyynl/lib/ynl.py
@@ -0,0 +1,1091 @@
+# SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+
+from collections import namedtuple
+from enum import Enum
+import functools
+import os
+import random
+import socket
+import struct
+from struct import Struct
+import sys
+import yaml
+import ipaddress
+import uuid
+import queue
+import selectors
+import time
+
+from .nlspec import SpecFamily
+
+#
+# Generic Netlink code which should really be in some library, but I can't quickly find one.
+#
+
+
+class Netlink:
+    # Netlink socket
+    SOL_NETLINK = 270
+
+    NETLINK_ADD_MEMBERSHIP = 1
+    NETLINK_CAP_ACK = 10
+    NETLINK_EXT_ACK = 11
+    NETLINK_GET_STRICT_CHK = 12
+
+    # Netlink message
+    NLMSG_ERROR = 2
+    NLMSG_DONE = 3
+
+    NLM_F_REQUEST = 1
+    NLM_F_ACK = 4
+    NLM_F_ROOT = 0x100
+    NLM_F_MATCH = 0x200
+
+    NLM_F_REPLACE = 0x100
+    NLM_F_EXCL = 0x200
+    NLM_F_CREATE = 0x400
+    NLM_F_APPEND = 0x800
+
+    NLM_F_CAPPED = 0x100
+    NLM_F_ACK_TLVS = 0x200
+
+    NLM_F_DUMP = NLM_F_ROOT | NLM_F_MATCH
+
+    NLA_F_NESTED = 0x8000
+    NLA_F_NET_BYTEORDER = 0x4000
+
+    NLA_TYPE_MASK = NLA_F_NESTED | NLA_F_NET_BYTEORDER
+
+    # Genetlink defines
+    NETLINK_GENERIC = 16
+
+    GENL_ID_CTRL = 0x10
+
+    # nlctrl
+    CTRL_CMD_GETFAMILY = 3
+
+    CTRL_ATTR_FAMILY_ID = 1
+    CTRL_ATTR_FAMILY_NAME = 2
+    CTRL_ATTR_MAXATTR = 5
+    CTRL_ATTR_MCAST_GROUPS = 7
+
+    CTRL_ATTR_MCAST_GRP_NAME = 1
+    CTRL_ATTR_MCAST_GRP_ID = 2
+
+    # Extack types
+    NLMSGERR_ATTR_MSG = 1
+    NLMSGERR_ATTR_OFFS = 2
+    NLMSGERR_ATTR_COOKIE = 3
+    NLMSGERR_ATTR_POLICY = 4
+    NLMSGERR_ATTR_MISS_TYPE = 5
+    NLMSGERR_ATTR_MISS_NEST = 6
+
+    # Policy types
+    NL_POLICY_TYPE_ATTR_TYPE = 1
+    NL_POLICY_TYPE_ATTR_MIN_VALUE_S = 2
+    NL_POLICY_TYPE_ATTR_MAX_VALUE_S = 3
+    NL_POLICY_TYPE_ATTR_MIN_VALUE_U = 4
+    NL_POLICY_TYPE_ATTR_MAX_VALUE_U = 5
+    NL_POLICY_TYPE_ATTR_MIN_LENGTH = 6
+    NL_POLICY_TYPE_ATTR_MAX_LENGTH = 7
+    NL_POLICY_TYPE_ATTR_POLICY_IDX = 8
+    NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE = 9
+    NL_POLICY_TYPE_ATTR_BITFIELD32_MASK = 10
+    NL_POLICY_TYPE_ATTR_PAD = 11
+    NL_POLICY_TYPE_ATTR_MASK = 12
+
+    AttrType = Enum('AttrType', ['flag', 'u8', 'u16', 'u32', 'u64',
+                                  's8', 's16', 's32', 's64',
+                                  'binary', 'string', 'nul-string',
+                                  'nested', 'nested-array',
+                                  'bitfield32', 'sint', 'uint'])
+
+class NlError(Exception):
+  def __init__(self, nl_msg):
+    self.nl_msg = nl_msg
+    self.error = -nl_msg.error
+
+  def __str__(self):
+    return f"Netlink error: {os.strerror(self.error)}\n{self.nl_msg}"
+
+
+class ConfigError(Exception):
+    pass
+
+
+class NlAttr:
+    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])
+        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]
+
+    @classmethod
+    def get_format(cls, attr_type, byte_order=None):
+        format = cls.type_formats[attr_type]
+        if byte_order:
+            return format.big if byte_order == "big-endian" \
+                else format.little
+        return format.native
+
+    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_auto_scalar(self, attr_type, byte_order=None):
+        if len(self.raw) != 4 and len(self.raw) != 8:
+            raise Exception(f"Auto-scalar len payload be 4 or 8 bytes, got {len(self.raw)}")
+        real_type = attr_type[0] + str(len(self.raw) * 8)
+        format = self.get_format(real_type, byte_order)
+        return format.unpack(self.raw)[0]
+
+    def as_strz(self):
+        return self.raw.decode('ascii')[:-1]
+
+    def as_bin(self):
+        return self.raw
+
+    def as_c_array(self, type):
+        format = self.get_format(type)
+        return [ x[0] for x in format.iter_unpack(self.raw) ]
+
+    def __repr__(self):
+        return f"[type:{self.type} len:{self._len}] {self.raw}"
+
+
+class NlAttrs:
+    def __init__(self, msg, offset=0):
+        self.attrs = []
+
+        while offset < len(msg):
+            attr = NlAttr(msg, offset)
+            offset += attr.full_len
+            self.attrs.append(attr)
+
+    def __iter__(self):
+        yield from self.attrs
+
+    def __repr__(self):
+        msg = ''
+        for a in self.attrs:
+            if msg:
+                msg += '\n'
+            msg += repr(a)
+        return msg
+
+
+class NlMsg:
+    def __init__(self, msg, offset, attr_space=None):
+        self.hdr = msg[offset : offset + 16]
+
+        self.nl_len, self.nl_type, self.nl_flags, self.nl_seq, self.nl_portid = \
+            struct.unpack("IHHII", self.hdr)
+
+        self.raw = msg[offset + 16 : offset + self.nl_len]
+
+        self.error = 0
+        self.done = 0
+
+        extack_off = None
+        if self.nl_type == Netlink.NLMSG_ERROR:
+            self.error = struct.unpack("i", self.raw[0:4])[0]
+            self.done = 1
+            extack_off = 20
+        elif self.nl_type == Netlink.NLMSG_DONE:
+            self.error = struct.unpack("i", self.raw[0:4])[0]
+            self.done = 1
+            extack_off = 4
+
+        self.extack = None
+        if self.nl_flags & Netlink.NLM_F_ACK_TLVS and extack_off:
+            self.extack = dict()
+            extack_attrs = NlAttrs(self.raw[extack_off:])
+            for extack in extack_attrs:
+                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_scalar('u32')
+                elif extack.type == Netlink.NLMSGERR_ATTR_MISS_NEST:
+                    self.extack['miss-nest'] = extack.as_scalar('u32')
+                elif extack.type == Netlink.NLMSGERR_ATTR_OFFS:
+                    self.extack['bad-attr-offs'] = extack.as_scalar('u32')
+                elif extack.type == Netlink.NLMSGERR_ATTR_POLICY:
+                    self.extack['policy'] = self._decode_policy(extack.raw)
+                else:
+                    if 'unknown' not in self.extack:
+                        self.extack['unknown'] = []
+                    self.extack['unknown'].append(extack)
+
+            if attr_space:
+                # We don't have the ability to parse nests yet, so only do global
+                if 'miss-type' in self.extack and 'miss-nest' not in self.extack:
+                    miss_type = self.extack['miss-type']
+                    if miss_type in attr_space.attrs_by_val:
+                        spec = attr_space.attrs_by_val[miss_type]
+                        self.extack['miss-type'] = spec['name']
+                        if 'doc' in spec:
+                            self.extack['miss-type-doc'] = spec['doc']
+
+    def _decode_policy(self, raw):
+        policy = {}
+        for attr in NlAttrs(raw):
+            if attr.type == Netlink.NL_POLICY_TYPE_ATTR_TYPE:
+                type = attr.as_scalar('u32')
+                policy['type'] = Netlink.AttrType(type).name
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_MIN_VALUE_S:
+                policy['min-value'] = attr.as_scalar('s64')
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_MAX_VALUE_S:
+                policy['max-value'] = attr.as_scalar('s64')
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_MIN_VALUE_U:
+                policy['min-value'] = attr.as_scalar('u64')
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_MAX_VALUE_U:
+                policy['max-value'] = attr.as_scalar('u64')
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_MIN_LENGTH:
+                policy['min-length'] = attr.as_scalar('u32')
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_MAX_LENGTH:
+                policy['max-length'] = attr.as_scalar('u32')
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_BITFIELD32_MASK:
+                policy['bitfield32-mask'] = attr.as_scalar('u32')
+            elif attr.type == Netlink.NL_POLICY_TYPE_ATTR_MASK:
+                policy['mask'] = attr.as_scalar('u64')
+        return policy
+
+    def cmd(self):
+        return self.nl_type
+
+    def __repr__(self):
+        msg = f"nl_len = {self.nl_len} ({len(self.raw)}) nl_flags = 0x{self.nl_flags:x} nl_type = {self.nl_type}"
+        if self.error:
+            msg += '\n\terror: ' + str(self.error)
+        if self.extack:
+            msg += '\n\textack: ' + repr(self.extack)
+        return msg
+
+
+class NlMsgs:
+    def __init__(self, data, attr_space=None):
+        self.msgs = []
+
+        offset = 0
+        while offset < len(data):
+            msg = NlMsg(data, offset, attr_space=attr_space)
+            offset += msg.nl_len
+            self.msgs.append(msg)
+
+    def __iter__(self):
+        yield from self.msgs
+
+
+genl_family_name_to_id = None
+
+
+def _genl_msg(nl_type, nl_flags, genl_cmd, genl_version, seq=None):
+    # we prepend length in _genl_msg_finalize()
+    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)
+    return nlmsg + genlmsg
+
+
+def _genl_msg_finalize(msg):
+    return struct.pack("I", len(msg) + 4) + msg
+
+
+def _genl_load_families():
+    with socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, Netlink.NETLINK_GENERIC) as sock:
+        sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
+
+        msg = _genl_msg(Netlink.GENL_ID_CTRL,
+                        Netlink.NLM_F_REQUEST | Netlink.NLM_F_ACK | Netlink.NLM_F_DUMP,
+                        Netlink.CTRL_CMD_GETFAMILY, 1)
+        msg = _genl_msg_finalize(msg)
+
+        sock.send(msg, 0)
+
+        global genl_family_name_to_id
+        genl_family_name_to_id = dict()
+
+        while True:
+            reply = sock.recv(128 * 1024)
+            nms = NlMsgs(reply)
+            for nl_msg in nms:
+                if nl_msg.error:
+                    print("Netlink error:", nl_msg.error)
+                    return
+                if nl_msg.done:
+                    return
+
+                gm = GenlMsg(nl_msg)
+                fam = dict()
+                for attr in NlAttrs(gm.raw):
+                    if attr.type == Netlink.CTRL_ATTR_FAMILY_ID:
+                        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_scalar('u32')
+                    elif attr.type == Netlink.CTRL_ATTR_MCAST_GROUPS:
+                        fam['mcast'] = dict()
+                        for entry in NlAttrs(attr.raw):
+                            mcast_name = None
+                            mcast_id = None
+                            for entry_attr in NlAttrs(entry.raw):
+                                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_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:
+                    genl_family_name_to_id[fam['name']] = fam
+
+
+class GenlMsg:
+    def __init__(self, nl_msg):
+        self.nl = nl_msg
+        self.genl_cmd, self.genl_version, _ = struct.unpack_from("BBH", nl_msg.raw, 0)
+        self.raw = nl_msg.raw[4:]
+
+    def cmd(self):
+        return self.genl_cmd
+
+    def __repr__(self):
+        msg = repr(self.nl)
+        msg += f"\tgenl_cmd = {self.genl_cmd} genl_ver = {self.genl_version}\n"
+        for a in self.raw_attrs:
+            msg += '\t\t' + repr(a) + '\n'
+        return msg
+
+
+class NetlinkProtocol:
+    def __init__(self, family_name, proto_num):
+        self.family_name = family_name
+        self.proto_num = proto_num
+
+    def _message(self, nl_type, nl_flags, seq=None):
+        if seq is None:
+            seq = random.randint(1, 1024)
+        nlmsg = struct.pack("HHII", nl_type, nl_flags, seq, 0)
+        return nlmsg
+
+    def message(self, flags, command, version, seq=None):
+        return self._message(command, flags, seq)
+
+    def _decode(self, nl_msg):
+        return nl_msg
+
+    def decode(self, ynl, nl_msg, op):
+        msg = self._decode(nl_msg)
+        if op is None:
+            op = ynl.rsp_by_value[msg.cmd()]
+        fixed_header_size = ynl._struct_size(op.fixed_header)
+        msg.raw_attrs = NlAttrs(msg.raw, fixed_header_size)
+        return msg
+
+    def get_mcast_id(self, mcast_name, mcast_groups):
+        if mcast_name not in mcast_groups:
+            raise Exception(f'Multicast group "{mcast_name}" not present in the spec')
+        return mcast_groups[mcast_name].value
+
+    def msghdr_size(self):
+        return 16
+
+
+class GenlProtocol(NetlinkProtocol):
+    def __init__(self, family_name):
+        super().__init__(family_name, Netlink.NETLINK_GENERIC)
+
+        global genl_family_name_to_id
+        if genl_family_name_to_id is None:
+            _genl_load_families()
+
+        self.genl_family = genl_family_name_to_id[family_name]
+        self.family_id = genl_family_name_to_id[family_name]['id']
+
+    def message(self, flags, command, version, seq=None):
+        nlmsg = self._message(self.family_id, flags, seq)
+        genlmsg = struct.pack("BBH", command, version, 0)
+        return nlmsg + genlmsg
+
+    def _decode(self, nl_msg):
+        return GenlMsg(nl_msg)
+
+    def get_mcast_id(self, mcast_name, mcast_groups):
+        if mcast_name not in self.genl_family['mcast']:
+            raise Exception(f'Multicast group "{mcast_name}" not present in the family')
+        return self.genl_family['mcast'][mcast_name]
+
+    def msghdr_size(self):
+        return super().msghdr_size() + 4
+
+
+class SpaceAttrs:
+    SpecValuesPair = namedtuple('SpecValuesPair', ['spec', 'values'])
+
+    def __init__(self, attr_space, attrs, outer = None):
+        outer_scopes = outer.scopes if outer else []
+        inner_scope = self.SpecValuesPair(attr_space, attrs)
+        self.scopes = [inner_scope] + outer_scopes
+
+    def lookup(self, name):
+        for scope in self.scopes:
+            if name in scope.spec:
+                if name in scope.values:
+                    return scope.values[name]
+                spec_name = scope.spec.yaml['name']
+                raise Exception(
+                    f"No value for '{name}' in attribute space '{spec_name}'")
+        raise Exception(f"Attribute '{name}' not defined in any attribute-set")
+
+
+#
+# YNL implementation details.
+#
+
+
+class YnlFamily(SpecFamily):
+    def __init__(self, def_path, schema=None, process_unknown=False,
+                 recv_size=0):
+        super().__init__(def_path, schema)
+
+        self.include_raw = False
+        self.process_unknown = process_unknown
+
+        try:
+            if self.proto == "netlink-raw":
+                self.nlproto = NetlinkProtocol(self.yaml['name'],
+                                               self.yaml['protonum'])
+            else:
+                self.nlproto = GenlProtocol(self.yaml['name'])
+        except KeyError:
+            raise Exception(f"Family '{self.yaml['name']}' not supported by the kernel")
+
+        self._recv_dbg = False
+        # Note that netlink will use conservative (min) message size for
+        # the first dump recv() on the socket, our setting will only matter
+        # from the second recv() on.
+        self._recv_size = recv_size if recv_size else 131072
+        # Netlink will always allocate at least PAGE_SIZE - sizeof(skb_shinfo)
+        # for a message, so smaller receive sizes will lead to truncation.
+        # Note that the min size for other families may be larger than 4k!
+        if self._recv_size < 4000:
+            raise ConfigError()
+
+        self.sock = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, self.nlproto.proto_num)
+        self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
+        self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_EXT_ACK, 1)
+        self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_GET_STRICT_CHK, 1)
+
+        self.async_msg_ids = set()
+        self.async_msg_queue = queue.Queue()
+
+        for msg in self.msgs.values():
+            if msg.is_async:
+                self.async_msg_ids.add(msg.rsp_value)
+
+        for op_name, op in self.ops.items():
+            bound_f = functools.partial(self._op, op_name)
+            setattr(self, op.ident_name, bound_f)
+
+
+    def ntf_subscribe(self, mcast_name):
+        mcast_id = self.nlproto.get_mcast_id(mcast_name, self.mcast_groups)
+        self.sock.bind((0, 0))
+        self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_ADD_MEMBERSHIP,
+                             mcast_id)
+
+    def set_recv_dbg(self, enabled):
+        self._recv_dbg = enabled
+
+    def _recv_dbg_print(self, reply, nl_msgs):
+        if not self._recv_dbg:
+            return
+        print("Recv: read", len(reply), "bytes,",
+              len(nl_msgs.msgs), "messages", file=sys.stderr)
+        for nl_msg in nl_msgs:
+            print("  ", nl_msg, file=sys.stderr)
+
+    def _encode_enum(self, attr_spec, value):
+        enum = self.consts[attr_spec['enum']]
+        if enum.type == 'flags' or attr_spec.get('enum-as-flags', False):
+            scalar = 0
+            if isinstance(value, str):
+                value = [value]
+            for single_value in value:
+                scalar += enum.entries[single_value].user_value(as_flags = True)
+            return scalar
+        else:
+            return enum.entries[value].user_value()
+
+    def _get_scalar(self, attr_spec, value):
+        try:
+            return int(value)
+        except (ValueError, TypeError) as e:
+            if 'enum' in attr_spec:
+                return self._encode_enum(attr_spec, value)
+            if attr_spec.display_hint:
+                return self._from_string(value, attr_spec)
+            raise e
+
+    def _add_attr(self, space, name, value, search_attrs):
+        try:
+            attr = self.attr_sets[space][name]
+        except KeyError:
+            raise Exception(f"Space '{space}' has no attribute '{name}'")
+        nl_type = attr.value
+
+        if attr.is_multi and isinstance(value, list):
+            attr_payload = b''
+            for subvalue in value:
+                attr_payload += self._add_attr(space, name, subvalue, search_attrs)
+            return attr_payload
+
+        if attr["type"] == 'nest':
+            nl_type |= Netlink.NLA_F_NESTED
+            attr_payload = b''
+            sub_space = attr['nested-attributes']
+            sub_attrs = SpaceAttrs(self.attr_sets[sub_space], value, search_attrs)
+            for subname, subvalue in value.items():
+                attr_payload += self._add_attr(sub_space, subname, subvalue, sub_attrs)
+        elif attr["type"] == 'flag':
+            if not value:
+                # If value is absent or false then skip attribute creation.
+                return b''
+            attr_payload = b''
+        elif attr["type"] == 'string':
+            attr_payload = str(value).encode('ascii') + b'\x00'
+        elif attr["type"] == 'binary':
+            if isinstance(value, bytes):
+                attr_payload = value
+            elif isinstance(value, str):
+                if attr.display_hint:
+                    attr_payload = self._from_string(value, attr)
+                else:
+                    attr_payload = bytes.fromhex(value)
+            elif isinstance(value, dict) and attr.struct_name:
+                attr_payload = self._encode_struct(attr.struct_name, value)
+            else:
+                raise Exception(f'Unknown type for binary attribute, value: {value}')
+        elif attr['type'] in NlAttr.type_formats or attr.is_auto_scalar:
+            scalar = self._get_scalar(attr, value)
+            if attr.is_auto_scalar:
+                attr_type = attr["type"][0] + ('32' if scalar.bit_length() <= 32 else '64')
+            else:
+                attr_type = attr["type"]
+            format = NlAttr.get_format(attr_type, attr.byte_order)
+            attr_payload = format.pack(scalar)
+        elif attr['type'] in "bitfield32":
+            scalar_value = self._get_scalar(attr, value["value"])
+            scalar_selector = self._get_scalar(attr, value["selector"])
+            attr_payload = struct.pack("II", scalar_value, scalar_selector)
+        elif attr['type'] == 'sub-message':
+            msg_format = self._resolve_selector(attr, search_attrs)
+            attr_payload = b''
+            if msg_format.fixed_header:
+                attr_payload += self._encode_struct(msg_format.fixed_header, value)
+            if msg_format.attr_set:
+                if msg_format.attr_set in self.attr_sets:
+                    nl_type |= Netlink.NLA_F_NESTED
+                    sub_attrs = SpaceAttrs(msg_format.attr_set, value, search_attrs)
+                    for subname, subvalue in value.items():
+                        attr_payload += self._add_attr(msg_format.attr_set,
+                                                       subname, subvalue, sub_attrs)
+                else:
+                    raise Exception(f"Unknown attribute-set '{msg_format.attr_set}'")
+        else:
+            raise Exception(f'Unknown type at {space} {name} {value} {attr["type"]}')
+
+        pad = b'\x00' * ((4 - len(attr_payload) % 4) % 4)
+        return struct.pack('HH', len(attr_payload) + 4, nl_type) + attr_payload + pad
+
+    def _decode_enum(self, raw, attr_spec):
+        enum = self.consts[attr_spec['enum']]
+        if enum.type == 'flags' or attr_spec.get('enum-as-flags', False):
+            i = 0
+            value = set()
+            while raw:
+                if raw & 1:
+                    value.add(enum.entries_by_val[i].name)
+                raw >>= 1
+                i += 1
+        else:
+            value = enum.entries_by_val[raw].name
+        return value
+
+    def _decode_binary(self, attr, attr_spec):
+        if attr_spec.struct_name:
+            decoded = self._decode_struct(attr.raw, attr_spec.struct_name)
+        elif attr_spec.sub_type:
+            decoded = attr.as_c_array(attr_spec.sub_type)
+            if 'enum' in attr_spec:
+                decoded = [ self._decode_enum(x, attr_spec) for x in decoded ]
+            elif attr_spec.display_hint:
+                decoded = [ self._formatted_string(x, attr_spec.display_hint)
+                            for x in decoded ]
+        else:
+            decoded = attr.as_bin()
+            if attr_spec.display_hint:
+                decoded = self._formatted_string(decoded, attr_spec.display_hint)
+        return decoded
+
+    def _decode_array_attr(self, attr, attr_spec):
+        decoded = []
+        offset = 0
+        while offset < len(attr.raw):
+            item = NlAttr(attr.raw, offset)
+            offset += item.full_len
+
+            if attr_spec["sub-type"] == 'nest':
+                subattrs = self._decode(NlAttrs(item.raw), attr_spec['nested-attributes'])
+                decoded.append({ item.type: subattrs })
+            elif attr_spec["sub-type"] == 'binary':
+                subattr = item.as_bin()
+                if attr_spec.display_hint:
+                    subattr = self._formatted_string(subattr, attr_spec.display_hint)
+                decoded.append(subattr)
+            elif attr_spec["sub-type"] in NlAttr.type_formats:
+                subattr = item.as_scalar(attr_spec['sub-type'], attr_spec.byte_order)
+                if 'enum' in attr_spec:
+                    subattr = self._decode_enum(subattr, attr_spec)
+                elif attr_spec.display_hint:
+                    subattr = self._formatted_string(subattr, attr_spec.display_hint)
+                decoded.append(subattr)
+            else:
+                raise Exception(f'Unknown {attr_spec["sub-type"]} with name {attr_spec["name"]}')
+        return decoded
+
+    def _decode_nest_type_value(self, attr, attr_spec):
+        decoded = {}
+        value = attr
+        for name in attr_spec['type-value']:
+            value = NlAttr(value.raw, 0)
+            decoded[name] = value.type
+        subattrs = self._decode(NlAttrs(value.raw), attr_spec['nested-attributes'])
+        decoded.update(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 _resolve_selector(self, attr_spec, search_attrs):
+        sub_msg = attr_spec.sub_message
+        if sub_msg not in self.sub_msgs:
+            raise Exception(f"No sub-message spec named {sub_msg} for {attr_spec.name}")
+        sub_msg_spec = self.sub_msgs[sub_msg]
+
+        selector = attr_spec.selector
+        value = search_attrs.lookup(selector)
+        if value not in sub_msg_spec.formats:
+            raise Exception(f"No message format for '{value}' in sub-message spec '{sub_msg}'")
+
+        spec = sub_msg_spec.formats[value]
+        return spec
+
+    def _decode_sub_msg(self, attr, attr_spec, search_attrs):
+        msg_format = self._resolve_selector(attr_spec, search_attrs)
+        decoded = {}
+        offset = 0
+        if msg_format.fixed_header:
+            decoded.update(self._decode_struct(attr.raw, msg_format.fixed_header));
+            offset = self._struct_size(msg_format.fixed_header)
+        if msg_format.attr_set:
+            if msg_format.attr_set in self.attr_sets:
+                subdict = self._decode(NlAttrs(attr.raw, offset), msg_format.attr_set)
+                decoded.update(subdict)
+            else:
+                raise Exception(f"Unknown attribute-set '{attr_space}' when decoding '{attr_spec.name}'")
+        return decoded
+
+    def _decode(self, attrs, space, outer_attrs = None):
+        rsp = dict()
+        if space:
+            attr_space = self.attr_sets[space]
+            search_attrs = SpaceAttrs(attr_space, rsp, outer_attrs)
+
+        for attr in attrs:
+            try:
+                attr_spec = attr_space.attrs_by_val[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
+
+            try:
+                if attr_spec["type"] == 'nest':
+                    subdict = self._decode(NlAttrs(attr.raw), attr_spec['nested-attributes'], search_attrs)
+                    decoded = subdict
+                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.is_auto_scalar:
+                    decoded = attr.as_auto_scalar(attr_spec['type'], attr_spec.byte_order)
+                elif attr_spec["type"] in NlAttr.type_formats:
+                    decoded = attr.as_scalar(attr_spec['type'], attr_spec.byte_order)
+                    if 'enum' in attr_spec:
+                        decoded = self._decode_enum(decoded, attr_spec)
+                    elif attr_spec.display_hint:
+                        decoded = self._formatted_string(decoded, attr_spec.display_hint)
+                elif attr_spec["type"] == 'indexed-array':
+                    decoded = self._decode_array_attr(attr, attr_spec)
+                elif attr_spec["type"] == 'bitfield32':
+                    value, selector = struct.unpack("II", attr.raw)
+                    if 'enum' in attr_spec:
+                        value = self._decode_enum(value, attr_spec)
+                        selector = self._decode_enum(selector, attr_spec)
+                    decoded = {"value": value, "selector": selector}
+                elif attr_spec["type"] == 'sub-message':
+                    decoded = self._decode_sub_msg(attr, attr_spec, search_attrs)
+                elif attr_spec["type"] == 'nest-type-value':
+                    decoded = self._decode_nest_type_value(attr, attr_spec)
+                else:
+                    if not self.process_unknown:
+                        raise Exception(f'Unknown {attr_spec["type"]} with name {attr_spec["name"]}')
+                    decoded = self._decode_unknown(attr)
+
+                self._rsp_add(rsp, attr_spec["name"], attr_spec.is_multi, decoded)
+            except:
+                print(f"Error decoding '{attr_spec.name}' from '{space}'")
+                raise
+
+        return rsp
+
+    def _decode_extack_path(self, attrs, attr_set, offset, target):
+        for attr in attrs:
+            try:
+                attr_spec = attr_set.attrs_by_val[attr.type]
+            except KeyError:
+                raise Exception(f"Space '{attr_set.name}' has no attribute with value '{attr.type}'")
+            if offset > target:
+                break
+            if offset == target:
+                return '.' + attr_spec.name
+
+            if offset + attr.full_len <= target:
+                offset += attr.full_len
+                continue
+            if attr_spec['type'] != 'nest':
+                raise Exception(f"Can't dive into {attr.type} ({attr_spec['name']}) for extack")
+            offset += 4
+            subpath = self._decode_extack_path(NlAttrs(attr.raw),
+                                               self.attr_sets[attr_spec['nested-attributes']],
+                                               offset, target)
+            if subpath is None:
+                return None
+            return '.' + attr_spec.name + subpath
+
+        return None
+
+    def _decode_extack(self, request, op, extack):
+        if 'bad-attr-offs' not in extack:
+            return
+
+        msg = self.nlproto.decode(self, NlMsg(request, 0, op.attr_set), op)
+        offset = self.nlproto.msghdr_size() + self._struct_size(op.fixed_header)
+        path = self._decode_extack_path(msg.raw_attrs, op.attr_set, offset,
+                                        extack['bad-attr-offs'])
+        if path:
+            del extack['bad-attr-offs']
+            extack['bad-attr'] = path
+
+    def _struct_size(self, name):
+        if name:
+            members = self.consts[name].members
+            size = 0
+            for m in members:
+                if m.type in ['pad', 'binary']:
+                    if m.struct:
+                        size += self._struct_size(m.struct)
+                    else:
+                        size += m.len
+                else:
+                    format = NlAttr.get_format(m.type, m.byte_order)
+                    size += format.size
+            return size
+        else:
+            return 0
+
+    def _decode_struct(self, data, name):
+        members = self.consts[name].members
+        attrs = dict()
+        offset = 0
+        for m in members:
+            value = None
+            if m.type == 'pad':
+                offset += m.len
+            elif m.type == 'binary':
+                if m.struct:
+                    len = self._struct_size(m.struct)
+                    value = self._decode_struct(data[offset : offset + len],
+                                                m.struct)
+                    offset += len
+                else:
+                    value = data[offset : offset + m.len]
+                    offset += m.len
+            else:
+                format = NlAttr.get_format(m.type, m.byte_order)
+                [ value ] = format.unpack_from(data, offset)
+                offset += format.size
+            if value is not None:
+                if m.enum:
+                    value = self._decode_enum(value, m)
+                elif m.display_hint:
+                    value = self._formatted_string(value, m.display_hint)
+                attrs[m.name] = value
+        return attrs
+
+    def _encode_struct(self, name, vals):
+        members = self.consts[name].members
+        attr_payload = b''
+        for m in members:
+            value = vals.pop(m.name) if m.name in vals else None
+            if m.type == 'pad':
+                attr_payload += bytearray(m.len)
+            elif m.type == 'binary':
+                if m.struct:
+                    if value is None:
+                        value = dict()
+                    attr_payload += self._encode_struct(m.struct, value)
+                else:
+                    if value is None:
+                        attr_payload += bytearray(m.len)
+                    else:
+                        attr_payload += bytes.fromhex(value)
+            else:
+                if value is None:
+                    value = 0
+                format = NlAttr.get_format(m.type, m.byte_order)
+                attr_payload += format.pack(value)
+        return attr_payload
+
+    def _formatted_string(self, raw, display_hint):
+        if display_hint == 'mac':
+            formatted = ':'.join('%02x' % b for b in raw)
+        elif display_hint == 'hex':
+            if isinstance(raw, int):
+                formatted = hex(raw)
+            else:
+                formatted = bytes.hex(raw, ' ')
+        elif display_hint in [ 'ipv4', 'ipv6' ]:
+            formatted = format(ipaddress.ip_address(raw))
+        elif display_hint == 'uuid':
+            formatted = str(uuid.UUID(bytes=raw))
+        else:
+            formatted = raw
+        return formatted
+
+    def _from_string(self, string, attr_spec):
+        if attr_spec.display_hint in ['ipv4', 'ipv6']:
+            ip = ipaddress.ip_address(string)
+            if attr_spec['type'] == 'binary':
+                raw = ip.packed
+            else:
+                raw = int(ip)
+        else:
+            raise Exception(f"Display hint '{attr_spec.display_hint}' not implemented"
+                            f" when parsing '{attr_spec['name']}'")
+        return raw
+
+    def handle_ntf(self, decoded):
+        msg = dict()
+        if self.include_raw:
+            msg['raw'] = decoded
+        op = self.rsp_by_value[decoded.cmd()]
+        attrs = self._decode(decoded.raw_attrs, op.attr_set.name)
+        if op.fixed_header:
+            attrs.update(self._decode_struct(decoded.raw, op.fixed_header))
+
+        msg['name'] = op['name']
+        msg['msg'] = attrs
+        self.async_msg_queue.put(msg)
+
+    def check_ntf(self):
+        while True:
+            try:
+                reply = self.sock.recv(self._recv_size, socket.MSG_DONTWAIT)
+            except BlockingIOError:
+                return
+
+            nms = NlMsgs(reply)
+            self._recv_dbg_print(reply, nms)
+            for nl_msg in nms:
+                if nl_msg.error:
+                    print("Netlink error in ntf!?", os.strerror(-nl_msg.error))
+                    print(nl_msg)
+                    continue
+                if nl_msg.done:
+                    print("Netlink done while checking for ntf!?")
+                    continue
+
+                decoded = self.nlproto.decode(self, nl_msg, None)
+                if decoded.cmd() not in self.async_msg_ids:
+                    print("Unexpected msg id while checking for ntf", decoded)
+                    continue
+
+                self.handle_ntf(decoded)
+
+    def poll_ntf(self, duration=None):
+        start_time = time.time()
+        selector = selectors.DefaultSelector()
+        selector.register(self.sock, selectors.EVENT_READ)
+
+        while True:
+            try:
+                yield self.async_msg_queue.get_nowait()
+            except queue.Empty:
+                if duration is not None:
+                    timeout = start_time + duration - time.time()
+                    if timeout <= 0:
+                        return
+                else:
+                    timeout = None
+                events = selector.select(timeout)
+                if events:
+                    self.check_ntf()
+
+    def operation_do_attributes(self, name):
+      """
+      For a given operation name, find and return a supported
+      set of attributes (as a dict).
+      """
+      op = self.find_operation(name)
+      if not op:
+        return None
+
+      return op['do']['request']['attributes'].copy()
+
+    def _encode_message(self, op, vals, flags, req_seq):
+        nl_flags = Netlink.NLM_F_REQUEST | Netlink.NLM_F_ACK
+        for flag in flags or []:
+            nl_flags |= flag
+
+        msg = self.nlproto.message(nl_flags, op.req_value, 1, req_seq)
+        if op.fixed_header:
+            msg += self._encode_struct(op.fixed_header, vals)
+        search_attrs = SpaceAttrs(op.attr_set, vals)
+        for name, value in vals.items():
+            msg += self._add_attr(op.attr_set.name, name, value, search_attrs)
+        msg = _genl_msg_finalize(msg)
+        return msg
+
+    def _ops(self, ops):
+        reqs_by_seq = {}
+        req_seq = random.randint(1024, 65535)
+        payload = b''
+        for (method, vals, flags) in ops:
+            op = self.ops[method]
+            msg = self._encode_message(op, vals, flags, req_seq)
+            reqs_by_seq[req_seq] = (op, msg, flags)
+            payload += msg
+            req_seq += 1
+
+        self.sock.send(payload, 0)
+
+        done = False
+        rsp = []
+        op_rsp = []
+        while not done:
+            reply = self.sock.recv(self._recv_size)
+            nms = NlMsgs(reply, attr_space=op.attr_set)
+            self._recv_dbg_print(reply, nms)
+            for nl_msg in nms:
+                if nl_msg.nl_seq in reqs_by_seq:
+                    (op, req_msg, req_flags) = reqs_by_seq[nl_msg.nl_seq]
+                    if nl_msg.extack:
+                        self._decode_extack(req_msg, op, nl_msg.extack)
+                else:
+                    op = None
+                    req_flags = []
+
+                if nl_msg.error:
+                    raise NlError(nl_msg)
+                if nl_msg.done:
+                    if nl_msg.extack:
+                        print("Netlink warning:")
+                        print(nl_msg)
+
+                    if Netlink.NLM_F_DUMP in req_flags:
+                        rsp.append(op_rsp)
+                    elif not op_rsp:
+                        rsp.append(None)
+                    elif len(op_rsp) == 1:
+                        rsp.append(op_rsp[0])
+                    else:
+                        rsp.append(op_rsp)
+                    op_rsp = []
+
+                    del reqs_by_seq[nl_msg.nl_seq]
+                    done = len(reqs_by_seq) == 0
+                    break
+
+                decoded = self.nlproto.decode(self, nl_msg, op)
+
+                # Check if this is a reply to our request
+                if nl_msg.nl_seq not in reqs_by_seq or decoded.cmd() != op.rsp_value:
+                    if decoded.cmd() in self.async_msg_ids:
+                        self.handle_ntf(decoded)
+                        continue
+                    else:
+                        print('Unexpected message: ' + repr(decoded))
+                        continue
+
+                rsp_msg = self._decode(decoded.raw_attrs, op.attr_set.name)
+                if op.fixed_header:
+                    rsp_msg.update(self._decode_struct(decoded.raw, op.fixed_header))
+                op_rsp.append(rsp_msg)
+
+        return rsp
+
+    def _op(self, method, vals, flags=None, dump=False):
+        req_flags = flags or []
+        if dump:
+            req_flags.append(Netlink.NLM_F_DUMP)
+
+        ops = [(method, vals, req_flags)]
+        return self._ops(ops)[0]
+
+    def do(self, method, vals, flags=None):
+        return self._op(method, vals, flags)
+
+    def dump(self, method, vals):
+        return self._op(method, vals, dump=True)
+
+    def do_multi(self, ops):
+        return self._ops(ops)