203 lines
8.0 KiB
Python
203 lines
8.0 KiB
Python
#
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# This file is part of pysnmp software.
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#
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# Copyright (c) 2005-2018, Ilya Etingof <etingof@gmail.com>
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# License: http://snmplabs.com/pysnmp/license.html
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#
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import os
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import shutil
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import sys
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import tempfile
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from pyasn1.compat.octets import str2octs
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from pysnmp.proto.rfc3412 import MsgAndPduDispatcher
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from pysnmp.proto.mpmod.rfc2576 import SnmpV1MessageProcessingModel, SnmpV2cMessageProcessingModel
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from pysnmp.proto.mpmod.rfc3412 import SnmpV3MessageProcessingModel
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from pysnmp.proto.secmod.rfc2576 import SnmpV1SecurityModel, SnmpV2cSecurityModel
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from pysnmp.proto.secmod.rfc3414 import SnmpUSMSecurityModel
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from pysnmp.proto.acmod import rfc3415, void
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from pysnmp.entity import observer
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from pysnmp import debug
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from pysnmp import error
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__all__ = ['SnmpEngine']
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class SnmpEngine(object):
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"""Creates SNMP engine object.
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SNMP engine object is central in SNMP v3 architecture. It is an umbrella
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object that coordinates interactions between all parts of SNMP v3 system.
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See :RFC:`3412#section-2.1` (where it is termed *The Dispatcher*).
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With PySNMP design, `SnmpEngine` is the only stateful object, all SNMP
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v3 operations require an instance of SNMP engine. Users do not normally
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request services directly from `SnmpEngine`, but pass it around to
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other PySNMP interfaces.
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It is possible to run multiple instances of `SnmpEngine` in the
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application. In a multithreaded environment, each thread that
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works with SNMP must have its own `SnmpEngine` instance.
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Parameters
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----------
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snmpEngineID : :py:class:`~pysnmp.proto.rfc1902.OctetString`
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Unique and unambiguous identifier of an SNMP engine.
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If not given, `snmpEngineID` is autogenerated and stored on
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the filesystem. See :RFC:`3411#section-3.1.1` for details.
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Examples
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--------
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>>> SnmpEngine()
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SnmpEngine(snmpEngineID=OctetString(hexValue='0x80004fb80567726f6d6d69742'))
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>>>
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"""
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def __init__(self, snmpEngineID=None, maxMessageSize=65507,
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msgAndPduDsp=None):
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self.cache = {}
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self.observer = observer.MetaObserver()
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if msgAndPduDsp is None:
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self.msgAndPduDsp = MsgAndPduDispatcher()
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else:
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self.msgAndPduDsp = msgAndPduDsp
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self.messageProcessingSubsystems = {
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SnmpV1MessageProcessingModel.messageProcessingModelID:
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SnmpV1MessageProcessingModel(),
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SnmpV2cMessageProcessingModel.messageProcessingModelID:
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SnmpV2cMessageProcessingModel(),
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SnmpV3MessageProcessingModel.messageProcessingModelID:
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SnmpV3MessageProcessingModel()
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}
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self.securityModels = {
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SnmpV1SecurityModel.securityModelID: SnmpV1SecurityModel(),
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SnmpV2cSecurityModel.securityModelID: SnmpV2cSecurityModel(),
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SnmpUSMSecurityModel.securityModelID: SnmpUSMSecurityModel()
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}
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self.accessControlModel = {
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void.Vacm.accessModelID: void.Vacm(),
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rfc3415.Vacm.accessModelID: rfc3415.Vacm()
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}
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self.transportDispatcher = None
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if self.msgAndPduDsp.mibInstrumController is None:
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raise error.PySnmpError(
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'MIB instrumentation does not yet exist'
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)
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snmpEngineMaxMessageSize, = self.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols(
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'__SNMP-FRAMEWORK-MIB', 'snmpEngineMaxMessageSize')
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snmpEngineMaxMessageSize.syntax = snmpEngineMaxMessageSize.syntax.clone(maxMessageSize)
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snmpEngineBoots, = self.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-FRAMEWORK-MIB',
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'snmpEngineBoots')
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snmpEngineBoots.syntax += 1
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origSnmpEngineID, = self.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-FRAMEWORK-MIB',
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'snmpEngineID')
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if snmpEngineID is None:
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self.snmpEngineID = origSnmpEngineID.syntax
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else:
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origSnmpEngineID.syntax = origSnmpEngineID.syntax.clone(snmpEngineID)
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self.snmpEngineID = origSnmpEngineID.syntax
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debug.logger & debug.flagApp and debug.logger(
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'SnmpEngine: using custom SNMP Engine ID: %s' % self.snmpEngineID.prettyPrint())
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# Attempt to make some of snmp Engine settings persistent.
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# This should probably be generalized as a non-volatile MIB store.
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persistentPath = os.path.join(tempfile.gettempdir(), '__pysnmp', self.snmpEngineID.prettyPrint())
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debug.logger & debug.flagApp and debug.logger('SnmpEngine: using persistent directory: %s' % persistentPath)
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if not os.path.exists(persistentPath):
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try:
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os.makedirs(persistentPath)
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except OSError:
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return
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f = os.path.join(persistentPath, 'boots')
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try:
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snmpEngineBoots.syntax = snmpEngineBoots.syntax.clone(open(f).read())
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except Exception:
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pass
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try:
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snmpEngineBoots.syntax += 1
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except Exception:
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snmpEngineBoots.syntax = snmpEngineBoots.syntax.clone(1)
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try:
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fd, fn = tempfile.mkstemp(dir=persistentPath)
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os.write(fd, str2octs(snmpEngineBoots.syntax.prettyPrint()))
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os.close(fd)
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shutil.move(fn, f)
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except Exception:
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debug.logger & debug.flagApp and debug.logger(
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'SnmpEngine: could not stored SNMP Engine Boots: %s' % sys.exc_info()[1])
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else:
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debug.logger & debug.flagApp and debug.logger(
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'SnmpEngine: stored SNMP Engine Boots: %s' % snmpEngineBoots.syntax.prettyPrint())
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def __repr__(self):
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return '%s(snmpEngineID=%r)' % (self.__class__.__name__, self.snmpEngineID)
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# Transport dispatcher bindings
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def __receiveMessageCbFun(self, transportDispatcher, transportDomain,
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transportAddress, wholeMsg):
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self.msgAndPduDsp.receiveMessage(
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self, transportDomain, transportAddress, wholeMsg
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)
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def __receiveTimerTickCbFun(self, timeNow):
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self.msgAndPduDsp.receiveTimerTick(self, timeNow)
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for mpHandler in self.messageProcessingSubsystems.values():
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mpHandler.receiveTimerTick(self, timeNow)
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for smHandler in self.securityModels.values():
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smHandler.receiveTimerTick(self, timeNow)
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def registerTransportDispatcher(self, transportDispatcher, recvId=None):
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if self.transportDispatcher is not None and \
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self.transportDispatcher is not transportDispatcher:
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raise error.PySnmpError(
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'Transport dispatcher already registered'
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)
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transportDispatcher.registerRecvCbFun(
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self.__receiveMessageCbFun, recvId
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)
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if self.transportDispatcher is None:
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transportDispatcher.registerTimerCbFun(
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self.__receiveTimerTickCbFun
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)
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self.transportDispatcher = transportDispatcher
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def unregisterTransportDispatcher(self, recvId=None):
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if self.transportDispatcher is None:
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raise error.PySnmpError(
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'Transport dispatcher not registered'
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)
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self.transportDispatcher.unregisterRecvCbFun(recvId)
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self.transportDispatcher.unregisterTimerCbFun()
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self.transportDispatcher = None
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def getMibBuilder(self):
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return self.msgAndPduDsp.mibInstrumController.mibBuilder
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# User app may attach opaque objects to SNMP Engine
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def setUserContext(self, **kwargs):
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self.cache.update(
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dict([('__%s' % k, kwargs[k]) for k in kwargs])
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)
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def getUserContext(self, arg):
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return self.cache.get('__%s' % arg)
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def delUserContext(self, arg):
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try:
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del self.cache['__%s' % arg]
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except KeyError:
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pass
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