cmk_base/snmp_utils.py

   1 #!/usr/bin/python
   2 # -*- encoding: utf-8; py-indent-offset: 4 -*-
   3 # +------------------------------------------------------------------+
   4 # |             ____ _               _        __  __ _  __           |
   5 # |            / ___| |__   ___  ___| | __   |  \/  | |/ /           |
   6 # |           | |   | '_ \ / _ \/ __| |/ /   | |\/| | ' /            |
   7 # |           | |___| | | |  __/ (__|   <    | |  | | . \            |
   8 # |            \____|_| |_|\___|\___|_|\_\___|_|  |_|_|\_\           |
   9 # |                                                                  |
  10 # | Copyright Mathias Kettner 2014             mk@mathias-kettner.de |
  11 # +------------------------------------------------------------------+
  12 #
  13 # This file is part of Check_MK.
  14 # The official homepage is at http://mathias-kettner.de/check_mk.
  15 #
  16 # check_mk is free software;  you can redistribute it and/or modify it
  17 # under the  terms of the  GNU General Public License  as published by
  18 # the Free Software Foundation in version 2.  check_mk is  distributed
  19 # in the hope that it will be useful, but WITHOUT ANY WARRANTY;  with-
  20 # out even the implied warranty of  MERCHANTABILITY  or  FITNESS FOR A
  21 # PARTICULAR PURPOSE. See the  GNU General Public License for more de-
  22 # tails. You should have  received  a copy of the  GNU  General Public
  23 # License along with GNU Make; see the file  COPYING.  If  not,  write
  24 # to the Free Software Foundation, Inc., 51 Franklin St,  Fifth Floor,
  25 # Boston, MA 02110-1301 USA.
  26
  27 import abc
  28 import functools
  29 from typing import NamedTuple, Union, Tuple, Optional  # pylint: disable=unused-import
  30
  31 OID_END = 0  # Suffix-part of OID that was not specified
  32 OID_STRING = -1  # Complete OID as string ".1.3.6.1.4.1.343...."
  33 OID_BIN = -2  # Complete OID as binary string "\x01\x03\x06\x01..."
  34 OID_END_BIN = -3  # Same, but just the end part
  35 OID_END_OCTET_STRING = -4  # yet same, but omit first byte (assuming that is the length byte)
  36
  37
  38 def BINARY(oid):
  39     """Tell Check_MK to process this OID as binary data to the check."""
  40     return "binary", oid
  41
  42
  43 def CACHED_OID(oid):
  44     """Use this to mark OIDs as being cached for regular checks,
  45     but not for discovery"""
  46     return "cached", oid
  47
  48
  49 def binstring_to_int(binstring):
  50     """Convert a string to an integer.
  51
  52     This is done by consideren the string to by a little endian byte string.
  53     Such strings are sometimes used by SNMP to encode 64 bit counters without
  54     needed COUNTER64 (which is not available in SNMP v1)."""
  55     value = 0
  56     mult = 1
  57     for byte in binstring[::-1]:
  58         value += mult * ord(byte)
  59         mult *= 256
  60     return value
  61
  62
  63 def is_snmpv3_host(host_config):
  64     return isinstance(host_config.credentials, tuple)
  65
  66
  67 # TODO: Be more specific about the possible tuples
  68 # if the credentials are a string, we use that as community,
  69 # if it is a four-tuple, we use it as V3 auth parameters:
  70 # (1) security level (-l)
  71 # (2) auth protocol (-a, e.g. 'md5')
  72 # (3) security name (-u)
  73 # (4) auth password (-A)
  74 # And if it is a six-tuple, it has the following additional arguments:
  75 # (5) privacy protocol (DES|AES) (-x)
  76 # (6) privacy protocol pass phrase (-X)
  77 SNMPCredentials = Union[str, Tuple[str, str, str, str], Tuple[str, str, str, str], Tuple[str, str]]
  78
  79 # Wraps the configuration of a host into a single object for the SNMP code
  80 SNMPHostConfig = NamedTuple(
  81     "SNMPHostConfig",
  82     [
  83         ("is_ipv6_primary", bool),
  84         ("hostname", str),
  85         ("ipaddress", str),
  86         ("credentials", SNMPCredentials),
  87         ("port", int),
  88         ("is_bulkwalk_host", bool),
  89         ("is_snmpv2or3_without_bulkwalk_host", bool),
  90         ("bulk_walk_size_of", int),
  91         # TODO: Cleanup to named tuple
  92         ("timing", dict),
  93         ("oid_range_limits", list),
  94     ])
  95
  96
  97 class ABCSNMPBackend(object):
  98     __metaclass__ = abc.ABCMeta
  99
 100     @abc.abstractmethod
 101     def get(self, host_config, oid, context_name=None):
 102         # type: (SNMPHostConfig, str, Optional[str]) -> Optional[str]
 103         """Fetch a single OID from the given host in the given SNMP context
 104
 105         The OID may end with .* to perform a GETNEXT request. Otherwise a GET
 106         request is sent to the given host.
 107         """
 108         raise NotImplementedError()
 109
 110
 111 class MutexScanRegistry(object):
 112     """Register scan functions that are checked before a fallback is used
 113
 114     Add any number of scan functions to a registry instance by decorating
 115     them like this:
 116
 117         @mutex_scan_registry_instance.register
 118         def my_snmp_scan_function(oid):
 119             ...
 120
 121     You can then declare a scan function to be a fallback to those functions
 122     by decorating it with "@mutex_scan_registry_instance.as_fallback",
 123     meaning that the fallback function will only be evaluated if all of the
 124     scan functions registered earlier return something falsey.
 125     """
 126
 127     def __init__(self):
 128         super(MutexScanRegistry, self).__init__()
 129         self._specific_scans = []
 130
 131     def _is_specific(self, oid):
 132         return any(scan(oid) for scan in self._specific_scans)
 133
 134     def register(self, scan_function):
 135         self._specific_scans.append(scan_function)
 136         return scan_function
 137
 138     def as_fallback(self, scan_function):
 139         @functools.wraps(scan_function)
 140         def wrapper(oid):
 141             if self._is_specific(oid):
 142                 return False
 143             return scan_function(oid)
 144
 145         return wrapper