iotop/genetlink.py

   1 '''
   2 Netlink message generation/parsing
   3
   4 Copyright 2007        Johannes Berg <johannes@sipsolutions.net>
   5
   6 GPLv2+; See copying for details.
   7 '''
   8
   9 import struct
  10 from iotop.netlink import NLM_F_REQUEST, NLMSG_MIN_TYPE, Message, parse_attributes
  11 from iotop.netlink import NulStrAttr, Connection, NETLINK_GENERIC
  12
  13 CTRL_CMD_UNSPEC       = 0
  14 CTRL_CMD_NEWFAMILY    = 1
  15 CTRL_CMD_DELFAMILY    = 2
  16 CTRL_CMD_GETFAMILY    = 3
  17 CTRL_CMD_NEWOPS       = 4
  18 CTRL_CMD_DELOPS       = 5
  19 CTRL_CMD_GETOPS       = 6
  20
  21 CTRL_ATTR_UNSPEC      = 0
  22 CTRL_ATTR_FAMILY_ID   = 1
  23 CTRL_ATTR_FAMILY_NAME = 2
  24 CTRL_ATTR_VERSION     = 3
  25 CTRL_ATTR_HDRSIZE     = 4
  26 CTRL_ATTR_MAXATTR     = 5
  27 CTRL_ATTR_OPS         = 6
  28
  29 class GenlHdr:
  30     def __init__(self, cmd, version = 0):
  31         self.cmd = cmd
  32         self.version = version
  33     def _dump(self):
  34         return struct.pack("BBxx", self.cmd, self.version)
  35
  36 def _genl_hdr_parse(data):
  37     return GenlHdr(*struct.unpack("BBxx", data))
  38
  39 GENL_ID_CTRL        = NLMSG_MIN_TYPE
  40
  41 class GeNlMessage(Message):
  42     def __init__(self, family, cmd, attrs=[], flags=0):
  43         self.cmd = cmd
  44         self.attrs = attrs
  45         self.family = family
  46         Message.__init__(self, family, flags=flags,
  47                          payload=[GenlHdr(self.cmd)]+attrs)
  48
  49     @staticmethod
  50     def recv(conn):
  51         msg = conn.recv()
  52         packet = msg.payload
  53         hdr = _genl_hdr_parse(packet[:4])
  54
  55         genlmsg = GeNlMessage(msg.type, hdr.cmd, [], msg.flags)
  56         genlmsg.attrs = parse_attributes(packet[4:])
  57         genlmsg.version = hdr.version
  58
  59         return genlmsg
  60
  61 class Controller:
  62     def __init__(self, conn):
  63         self.conn = conn
  64     def get_family_id(self, family):
  65         a = NulStrAttr(CTRL_ATTR_FAMILY_NAME, family)
  66         m = GeNlMessage(GENL_ID_CTRL, CTRL_CMD_GETFAMILY,
  67                         flags=NLM_F_REQUEST, attrs=[a])
  68         m.send(self.conn)
  69         m = GeNlMessage.recv(self.conn)
  70         return m.attrs[CTRL_ATTR_FAMILY_ID].u16()
  71
  72 connection = Connection(NETLINK_GENERIC)
  73 controller = Controller(connection)