cmk_base/classic_snmp.py

   1 #!/usr/bin/env 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 os
  28 import subprocess
  29 import signal
  30
  31 import cmk.utils.tty as tty
  32 from cmk.utils.exceptions import MKGeneralException, MKTimeout
  33
  34 import cmk_base.console as console
  35 import cmk_base.snmp_utils as snmp_utils
  36 from cmk_base.exceptions import MKSNMPError
  37
  38 #.
  39 #   .--SNMP interface------------------------------------------------------.
  40 #   | ____  _   _ __  __ ____    _       _             __                  |
  41 #   |/ ___|| \ | |  \/  |  _ \  (_)_ __ | |_ ___ _ __ / _| __ _  ___ ___   |
  42 #   |\___ \|  \| | |\/| | |_) | | | '_ \| __/ _ \ '__| |_ / _` |/ __/ _ \  |
  43 #   | ___) | |\  | |  | |  __/  | | | | | ||  __/ |  |  _| (_| | (_|  __/  |
  44 #   ||____/|_| \_|_|  |_|_|     |_|_| |_|\__\___|_|  |_|  \__,_|\___\___|  |
  45 #   |                                                                      |
  46 #   +----------------------------------------------------------------------+
  47 #   | Implements the neccessary function for Check_MK                      |
  48 #   '----------------------------------------------------------------------'
  49
  50
  51 def walk(host_config, oid, hex_plain=False, context_name=None):
  52     protospec = _snmp_proto_spec(host_config)
  53
  54     ipaddress = host_config.ipaddress
  55     if protospec == "udp6:":
  56         ipaddress = "[" + ipaddress + "]"
  57     portspec = _snmp_port_spec(host_config)
  58     command = _snmp_walk_command(host_config, context_name)
  59     command += ["-OQ", "-OU", "-On", "-Ot", "%s%s%s" % (protospec, ipaddress, portspec), oid]
  60
  61     console.vverbose("Running '%s'\n" % subprocess.list2cmdline(command))
  62
  63     snmp_process = None
  64     exitstatus = None
  65     rowinfo = []
  66     try:
  67         snmp_process = subprocess.Popen(
  68             command,
  69             close_fds=True,
  70             stdin=open(os.devnull),
  71             stdout=subprocess.PIPE,
  72             stderr=subprocess.PIPE)
  73
  74         rowinfo = _get_rowinfo_from_snmp_process(snmp_process, hex_plain)
  75
  76     except MKTimeout:
  77         # On timeout exception try to stop the process to prevent child process "leakage"
  78         if snmp_process:
  79             os.kill(snmp_process.pid, signal.SIGTERM)
  80             snmp_process.wait()
  81         raise
  82
  83     finally:
  84         # The stdout and stderr pipe are not closed correctly on a MKTimeout
  85         # Normally these pipes getting closed after p.communicate finishes
  86         # Closing them a second time in a OK scenario won't hurt neither..
  87         if snmp_process:
  88             exitstatus = snmp_process.wait()
  89             error = snmp_process.stderr.read()
  90             snmp_process.stdout.close()
  91             snmp_process.stderr.close()
  92
  93     if exitstatus:
  94         console.verbose(tty.red + tty.bold + "ERROR: " + tty.normal +
  95                         "SNMP error: %s\n" % error.strip())
  96         raise MKSNMPError(
  97             "SNMP Error on %s: %s (Exit-Code: %d)" % (ipaddress, error.strip(), exitstatus))
  98     return rowinfo
  99
 100
 101 def _get_rowinfo_from_snmp_process(snmp_process, hex_plain):
 102     line_iter = snmp_process.stdout.xreadlines()
 103     # Ugly(1): in some cases snmpwalk inserts line feed within one
 104     # dataset. This happens for example on hexdump outputs longer
 105     # than a few bytes. Those dumps are enclosed in double quotes.
 106     # So if the value begins with a double quote, but the line
 107     # does not end with a double quote, we take the next line(s) as
 108     # a continuation line.
 109     rowinfo = []
 110     while True:
 111         try:
 112             line = line_iter.next().strip()
 113         except StopIteration:
 114             break
 115
 116         parts = line.split('=', 1)
 117         if len(parts) < 2:
 118             continue  # broken line, must contain =
 119         oid = parts[0].strip()
 120         value = parts[1].strip()
 121         # Filter out silly error messages from snmpwalk >:-P
 122         if value.startswith('No more variables') or value.startswith('End of MIB') \
 123            or value.startswith('No Such Object available') \
 124            or value.startswith('No Such Instance currently exists'):
 125             continue
 126
 127         if value == '"' or (len(value) > 1 and value[0] == '"' and
 128                             (value[-1] != '"')):  # to be continued
 129             while True:  # scan for end of this dataset
 130                 nextline = line_iter.next().strip()
 131                 value += " " + nextline
 132                 if value[-1] == '"':
 133                     break
 134         rowinfo.append((oid, strip_snmp_value(value, hex_plain)))
 135     return rowinfo
 136
 137
 138 class ClassicSNMPBackend(snmp_utils.ABCSNMPBackend):
 139     def get(self, host_config, oid, context_name=None):
 140         if oid.endswith(".*"):
 141             oid_prefix = oid[:-2]
 142             commandtype = "getnext"
 143         else:
 144             oid_prefix = oid
 145             commandtype = "get"
 146
 147         protospec = _snmp_proto_spec(host_config)
 148         ipaddress = host_config.ipaddress
 149         if protospec == "udp6:":
 150             ipaddress = "[" + ipaddress + "]"
 151         portspec = _snmp_port_spec(host_config)
 152         command = _snmp_base_command(commandtype, host_config, context_name) + \
 153                    [ "-On", "-OQ", "-Oe", "-Ot",
 154                      "%s%s%s" % (protospec, ipaddress, portspec),
 155                      oid_prefix ]
 156
 157         console.vverbose("Running '%s'\n" % subprocess.list2cmdline(command))
 158
 159         snmp_process = subprocess.Popen(
 160             command, close_fds=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
 161         exitstatus = snmp_process.wait()
 162         if exitstatus:
 163             console.verbose(tty.red + tty.bold + "ERROR: " + tty.normal + "SNMP error\n")
 164             console.verbose(snmp_process.stderr.read() + "\n")
 165             return None
 166
 167         line = snmp_process.stdout.readline().strip()
 168         if not line:
 169             console.verbose("Error in response to snmpget.\n")
 170             return None
 171
 172         item, value = line.split("=", 1)
 173         value = value.strip()
 174         console.vverbose("SNMP answer: ==> [%s]\n" % value)
 175         if value.startswith('No more variables') or value.startswith('End of MIB') \
 176            or value.startswith('No Such Object available') or value.startswith('No Such Instance currently exists'):
 177             value = None
 178
 179         # In case of .*, check if prefix is the one we are looking for
 180         if commandtype == "getnext" and not item.startswith(oid_prefix + "."):
 181             value = None
 182
 183         # Strip quotes
 184         if value and value.startswith('"') and value.endswith('"'):
 185             value = value[1:-1]
 186         return value
 187
 188
 189 def _snmp_port_spec(host_config):
 190     if host_config.port == 161:
 191         return ""
 192     return ":%d" % host_config.port
 193
 194
 195 def _snmp_proto_spec(host_config):
 196     if host_config.is_ipv6_primary:
 197         return "udp6:"
 198
 199     return ""
 200
 201
 202 # Returns command lines for snmpwalk and snmpget including
 203 # options for authentication. This handles communities and
 204 # authentication for SNMP V3. Also bulkwalk hosts
 205 def _snmp_walk_command(host_config, context_name):
 206     return _snmp_base_command('walk', host_config, context_name) + ["-Cc"]
 207
 208
 209 # if the credentials are a string, we use that as community,
 210 # if it is a four-tuple, we use it as V3 auth parameters:
 211 # (1) security level (-l)
 212 # (2) auth protocol (-a, e.g. 'md5')
 213 # (3) security name (-u)
 214 # (4) auth password (-A)
 215 # And if it is a six-tuple, it has the following additional arguments:
 216 # (5) privacy protocol (DES|AES) (-x)
 217 # (6) privacy protocol pass phrase (-X)
 218 def _snmp_base_command(what, host_config, context_name):
 219     options = []
 220
 221     if what == 'get':
 222         command = ['snmpget']
 223     elif what == 'getnext':
 224         command = ['snmpgetnext', '-Cf']
 225     elif host_config.is_bulkwalk_host:
 226         command = ['snmpbulkwalk']
 227
 228         options.append("-Cr%d" % host_config.bulk_walk_size_of)
 229     else:
 230         command = ['snmpwalk']
 231
 232     if not snmp_utils.is_snmpv3_host(host_config):
 233         # Handle V1 and V2C
 234         if host_config.is_bulkwalk_host:
 235             options.append('-v2c')
 236         else:
 237             if what == 'walk':
 238                 command = ['snmpwalk']
 239             if host_config.is_snmpv2or3_without_bulkwalk_host:
 240                 options.append('-v2c')
 241             else:
 242                 options.append('-v1')
 243
 244         options += ["-c", host_config.credentials]
 245
 246     else:
 247         # Handle V3
 248         if len(host_config.credentials) == 6:
 249             options += [
 250                 "-v3", "-l", host_config.credentials[0], "-a", host_config.credentials[1], "-u",
 251                 host_config.credentials[2], "-A", host_config.credentials[3], "-x",
 252                 host_config.credentials[4], "-X", host_config.credentials[5]
 253             ]
 254         elif len(host_config.credentials) == 4:
 255             options += [
 256                 "-v3", "-l", host_config.credentials[0], "-a", host_config.credentials[1], "-u",
 257                 host_config.credentials[2], "-A", host_config.credentials[3]
 258             ]
 259         elif len(host_config.credentials) == 2:
 260             options += ["-v3", "-l", host_config.credentials[0], "-u", host_config.credentials[1]]
 261         else:
 262             raise MKGeneralException("Invalid SNMP credentials '%r' for host %s: must be "
 263                                      "string, 2-tuple, 4-tuple or 6-tuple" %
 264                                      (host_config.credentials, host_config.hostname))
 265
 266     # Do not load *any* MIB files. This save lot's of CPU.
 267     options += ["-m", "", "-M", ""]
 268
 269     # Configuration of timing and retries
 270     settings = host_config.timing
 271     if "timeout" in settings:
 272         options += ["-t", "%0.2f" % settings["timeout"]]
 273     if "retries" in settings:
 274         options += ["-r", "%d" % settings["retries"]]
 275
 276     if context_name is not None:
 277         options += ["-n", context_name]
 278
 279     return command + options
 280
 281
 282 #.
 283 #   .--SNMP helpers--------------------------------------------------------.
 284 #   |     ____  _   _ __  __ ____    _          _                          |
 285 #   |    / ___|| \ | |  \/  |  _ \  | |__   ___| |_ __   ___ _ __ ___      |
 286 #   |    \___ \|  \| | |\/| | |_) | | '_ \ / _ \ | '_ \ / _ \ '__/ __|     |
 287 #   |     ___) | |\  | |  | |  __/  | | | |  __/ | |_) |  __/ |  \__ \     |
 288 #   |    |____/|_| \_|_|  |_|_|     |_| |_|\___|_| .__/ \___|_|  |___/     |
 289 #   |                                            |_|                       |
 290 #   +----------------------------------------------------------------------+
 291 #   | Internal helpers for processing SNMP things                          |
 292 #   '----------------------------------------------------------------------'
 293
 294
 295 def strip_snmp_value(value, hex_plain=False):
 296     v = value.strip()
 297     if v.startswith('"'):
 298         v = v[1:-1]
 299         if len(v) > 2 and _is_hex_string(v):
 300             return value if hex_plain else _convert_from_hex(v)
 301         # Fix for non hex encoded string which have been somehow encoded by the
 302         # netsnmp command line tools. An example:
 303         # Checking windows systems via SNMP with hr_fs: disk names like c:\
 304         # are reported as c:\\, fix this to single \
 305         return v.strip().replace('\\\\', '\\')
 306     return v
 307
 308
 309 def _is_hex_string(value):
 310     # as far as I remember, snmpwalk puts a trailing space within
 311     # the quotes in case of hex strings. So we require that space
 312     # to be present in order make sure, we really deal with a hex string.
 313     if value[-1] != ' ':
 314         return False
 315     hexdigits = "0123456789abcdefABCDEF"
 316     n = 0
 317     for x in value:
 318         if n % 3 == 2:
 319             if x != ' ':
 320                 return False
 321         else:
 322             if x not in hexdigits:
 323                 return False
 324         n += 1
 325     return True
 326
 327
 328 def _convert_from_hex(value):
 329     hexparts = value.split()
 330     r = ""
 331     for hx in hexparts:
 332         r += chr(int(hx, 16))
 333     return r