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