238 lines
6.8 KiB
Python
238 lines
6.8 KiB
Python
#
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# (Generic) Netlink message generation/parsing
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# Copyright (c) 2007 Johannes Berg <johannes@sipsolutions.net>
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# Copyright (c) 2014 Intel Corporation
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#
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# This software may be distributed under the terms of the BSD license.
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# See README for more details.
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import struct, socket
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# flags
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NLM_F_REQUEST = 1
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NLM_F_MULTI = 2
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NLM_F_ACK = 4
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NLM_F_ECHO = 8
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# types
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NLMSG_NOOP = 1
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NLMSG_ERROR = 2
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NLMSG_DONE = 3
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NLMSG_OVERRUN = 4
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NLMSG_MIN_TYPE = 0x10
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class Attr(object):
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def __init__(self, attr_type, data, *values):
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self._type = attr_type
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if len(values):
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self._data = struct.pack(data, *values)
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else:
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self._data = data
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def _dump(self):
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hdr = struct.pack("HH", len(self._data) + 4, self._type)
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length = len(self._data)
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pad = ((length + 4 - 1) & ~3 ) - length
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return hdr + self._data + '\0' * pad
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def __repr__(self):
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return '<Attr type %d, data "%s">' % (self._type, repr(self._data))
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def u16(self):
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return struct.unpack('H', self._data)[0]
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def s16(self):
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return struct.unpack('h', self._data)[0]
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def u32(self):
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return struct.unpack('I', self._data)[0]
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def s32(self):
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return struct.unpack('i', self._data)[0]
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def str(self):
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return self._data
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def nulstr(self):
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return self._data.split('\0')[0]
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def nested(self):
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return parse_attributes(self._data)
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class StrAttr(Attr):
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def __init__(self, attr_type, data):
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Attr.__init__(self, attr_type, "%ds" % len(data), data)
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class NulStrAttr(Attr):
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def __init__(self, attr_type, data):
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Attr.__init__(self, attr_type, "%dsB" % len(data), data, 0)
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class U32Attr(Attr):
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def __init__(self, attr_type, val):
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Attr.__init__(self, attr_type, "I", val)
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class U8Attr(Attr):
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def __init__(self, attr_type, val):
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Attr.__init__(self, attr_type, "B", val)
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class FlagAttr(Attr):
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def __init__(self, attr_type):
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Attr.__init__(self, attr_type, "")
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class Nested(Attr):
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def __init__(self, attr_type, attrs):
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self.attrs = attrs
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self.type = attr_type
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def _dump(self):
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contents = []
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for attr in self.attrs:
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contents.append(attr._dump())
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contents = ''.join(contents)
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length = len(contents)
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hdr = struct.pack("HH", length+4, self.type)
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return hdr + contents
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NETLINK_ROUTE = 0
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NETLINK_UNUSED = 1
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NETLINK_USERSOCK = 2
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NETLINK_FIREWALL = 3
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NETLINK_INET_DIAG = 4
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NETLINK_NFLOG = 5
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NETLINK_XFRM = 6
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NETLINK_SELINUX = 7
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NETLINK_ISCSI = 8
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NETLINK_AUDIT = 9
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NETLINK_FIB_LOOKUP = 10
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NETLINK_CONNECTOR = 11
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NETLINK_NETFILTER = 12
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NETLINK_IP6_FW = 13
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NETLINK_DNRTMSG = 14
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NETLINK_KOBJECT_UEVENT = 15
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NETLINK_GENERIC = 16
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class Message(object):
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def __init__(self, msg_type, flags=0, seq=-1, payload=None):
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self.type = msg_type
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self.flags = flags
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self.seq = seq
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self.pid = -1
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payload = payload or []
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if isinstance(payload, list):
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contents = []
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for attr in payload:
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contents.append(attr._dump())
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self.payload = ''.join(contents)
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else:
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self.payload = payload
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def send(self, conn):
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if self.seq == -1:
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self.seq = conn.seq()
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self.pid = conn.pid
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length = len(self.payload)
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hdr = struct.pack("IHHII", length + 4*4, self.type,
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self.flags, self.seq, self.pid)
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conn.send(hdr + self.payload)
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def __repr__(self):
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return '<netlink.Message type=%d, pid=%d, seq=%d, flags=0x%x "%s">' % (
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self.type, self.pid, self.seq, self.flags, repr(self.payload))
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@property
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def ret(self):
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assert self.type == NLMSG_ERROR
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return struct.unpack("i", self.payload[:4])[0]
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def send_and_recv(self, conn):
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self.send(conn)
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while True:
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m = conn.recv()
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if m.seq == self.seq:
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return m
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class Connection(object):
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def __init__(self, nltype, groups=0, unexpected_msg_handler=None):
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self.descriptor = socket.socket(socket.AF_NETLINK,
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socket.SOCK_RAW, nltype)
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self.descriptor.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 65536)
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self.descriptor.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 65536)
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self.descriptor.bind((0, groups))
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self.pid, self.groups = self.descriptor.getsockname()
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self._seq = 0
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self.unexpected = unexpected_msg_handler
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def send(self, msg):
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self.descriptor.send(msg)
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def recv(self):
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contents = self.descriptor.recv(16384)
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# XXX: python doesn't give us message flags, check
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# len(contents) vs. msglen for TRUNC
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msglen, msg_type, flags, seq, pid = struct.unpack("IHHII",
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contents[:16])
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msg = Message(msg_type, flags, seq, contents[16:])
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msg.pid = pid
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if msg.type == NLMSG_ERROR:
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import os
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errno = msg.ret
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if errno < 0:
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err = OSError("Netlink error: %s (%d)" % (
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os.strerror(-errno), -errno))
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err.errno = -errno
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raise err
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return msg
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def seq(self):
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self._seq += 1
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return self._seq
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def parse_attributes(data):
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attrs = {}
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while len(data):
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attr_len, attr_type = struct.unpack("HH", data[:4])
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attrs[attr_type] = Attr(attr_type, data[4:attr_len])
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attr_len = ((attr_len + 4 - 1) & ~3 )
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data = data[attr_len:]
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return attrs
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CTRL_CMD_UNSPEC = 0
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CTRL_CMD_NEWFAMILY = 1
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CTRL_CMD_DELFAMILY = 2
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CTRL_CMD_GETFAMILY = 3
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CTRL_CMD_NEWOPS = 4
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CTRL_CMD_DELOPS = 5
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CTRL_CMD_GETOPS = 6
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CTRL_ATTR_UNSPEC = 0
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CTRL_ATTR_FAMILY_ID = 1
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CTRL_ATTR_FAMILY_NAME = 2
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CTRL_ATTR_VERSION = 3
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CTRL_ATTR_HDRSIZE = 4
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CTRL_ATTR_MAXATTR = 5
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CTRL_ATTR_OPS = 6
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class GenlHdr(object):
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def __init__(self, cmd, version = 0):
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self.cmd = cmd
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self.version = version
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def _dump(self):
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return struct.pack("BBxx", self.cmd, self.version)
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def _genl_hdr_parse(data):
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return GenlHdr(*struct.unpack("BBxx", data))
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GENL_ID_CTRL = NLMSG_MIN_TYPE
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class GenlMessage(Message):
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def __init__(self, family, cmd, attrs=[], flags=0):
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Message.__init__(self, family, flags=flags, payload=[GenlHdr(cmd)] + attrs)
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class GenlController(object):
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def __init__(self, conn):
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self.conn = conn
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def get_family_id(self, family):
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a = NulStrAttr(CTRL_ATTR_FAMILY_NAME, family)
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m = GenlMessage(GENL_ID_CTRL, CTRL_CMD_GETFAMILY, flags=NLM_F_REQUEST, attrs=[a])
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m.send(self.conn)
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m = self.conn.recv()
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gh = _genl_hdr_parse(m.payload[:4])
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attrs = parse_attributes(m.payload[4:])
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return attrs[CTRL_ATTR_FAMILY_ID].u16()
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genl_controller = GenlController(Connection(NETLINK_GENERIC))
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