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
  11 from iotop.netlink import parse_attributes
  12 from iotop.netlink import NulStrAttr, Connection, NETLINK_GENERIC
  13
  14 CTRL_CMD_UNSPEC = 0
  15 CTRL_CMD_NEWFAMILY = 1
  16 CTRL_CMD_DELFAMILY = 2
  17 CTRL_CMD_GETFAMILY = 3
  18 CTRL_CMD_NEWOPS = 4
  19 CTRL_CMD_DELOPS = 5
  20 CTRL_CMD_GETOPS = 6
  21
  22 CTRL_ATTR_UNSPEC = 0
  23 CTRL_ATTR_FAMILY_ID = 1
  24 CTRL_ATTR_FAMILY_NAME = 2
  25 CTRL_ATTR_VERSION = 3
  26 CTRL_ATTR_HDRSIZE = 4
  27 CTRL_ATTR_MAXATTR = 5
  28 CTRL_ATTR_OPS = 6
  29
  30
  31 class GenlHdr:
  32     def __init__(self, cmd, version=0):
  33         self.cmd = cmd
  34         self.version = version
  35
  36     def _dump(self):
  37         return struct.pack("BBxx", self.cmd, self.version)
  38
  39
  40 def _genl_hdr_parse(data):
  41     return GenlHdr(*struct.unpack("BBxx", data))
  42
  43 GENL_ID_CTRL = NLMSG_MIN_TYPE
  44
  45
  46 class GeNlMessage(Message):
  47     def __init__(self, family, cmd, attrs=[], flags=0):
  48         self.cmd = cmd
  49         self.attrs = attrs
  50         self.family = family
  51         Message.__init__(self, family, flags=flags,
  52                          payload=[GenlHdr(self.cmd)] + attrs)
  53
  54     @staticmethod
  55     def recv(conn):
  56         msg = conn.recv()
  57         packet = msg.payload
  58         hdr = _genl_hdr_parse(packet[:4])
  59
  60         genlmsg = GeNlMessage(msg.type, hdr.cmd, [], msg.flags)
  61         genlmsg.attrs = parse_attributes(packet[4:])
  62         genlmsg.version = hdr.version
  63
  64         return genlmsg
  65
  66
  67 class Controller:
  68     def __init__(self, conn):
  69         self.conn = conn
  70
  71     def get_family_id(self, family):
  72         a = NulStrAttr(CTRL_ATTR_FAMILY_NAME, family)
  73         m = GeNlMessage(GENL_ID_CTRL, CTRL_CMD_GETFAMILY,
  74                         flags=NLM_F_REQUEST, attrs=[a])
  75         m.send(self.conn)
  76         m = GeNlMessage.recv(self.conn)
  77         return m.attrs[CTRL_ATTR_FAMILY_ID].u16()
  78
  79 connection = Connection(NETLINK_GENERIC)
  80 controller = Controller(connection)