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#
# This file is part of pysnmp software.
#
# Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
# License: http://snmplabs.com/pysnmp/license.html
#
from time import time
from pysnmp.proto.api import verdec
from pysnmp.proto import api
from pysnmp.proto import error
from pysnmp import debug
from pyasn1.codec.ber import encoder, decoder
__all__ = []
class AbstractSnmpDispatcher(object):
"""Creates SNMP message dispatcher object.
`SnmpDispatcher` object manages send and receives SNMP PDU
messages through underlying transport dispatcher and dispatches
them to the callers.
`SnmpDispatcher` is the only stateful object, all `hlapi.v1arch` SNMP
operations require an instance of `SnmpDispatcher`. Users do not normally
request services directly from `SnmpDispather`, but pass it around to
other `hlapi.v1arch` interfaces.
It is possible to run multiple instances of `SnmpDispatcher` in the
application. In a multithreaded environment, each thread that
works with SNMP must have its own `SnmpDispatcher` instance.
"""
PROTO_DISPATCHER = None
def __init__(self, transportDispatcher=None):
if transportDispatcher:
self.transportDispatcher = transportDispatcher
else:
self.transportDispatcher = self.PROTO_DISPATCHER()
self._automaticDispatcher = transportDispatcher is not self.transportDispatcher
self._configuredTransports = set()
self._pendingReqs = {}
self.transportDispatcher.registerRecvCbFun(self._recvCb)
self.transportDispatcher.registerTimerCbFun(self._timerCb)
self.cache = {}
def __repr__(self):
return '%s(transportDispatcher=%s)' % (self.__class__.__name__, self.transportDispatcher)
def close(self):
self.transportDispatcher.unregisterRecvCbFun()
self.transportDispatcher.unregisterTimerCbFun()
if self._automaticDispatcher:
self.transportDispatcher.close()
for requestId, stateInfo in self._pendingReqs.items():
cbFun = stateInfo['cbFun']
cbCtx = stateInfo['cbCtx']
if cbFun:
cbFun(self, 'Request #%d terminated' % requestId, None, cbCtx)
self._pendingReqs.clear()
def sendPdu(self, authData, transportTarget, reqPdu, cbFun=None, cbCtx=None):
if (self._automaticDispatcher and
transportTarget.TRANSPORT_DOMAIN not in self._configuredTransports):
self.transportDispatcher.registerTransport(
transportTarget.TRANSPORT_DOMAIN, transportTarget.PROTO_TRANSPORT().openClientMode()
)
self._configuredTransports.add(transportTarget.TRANSPORT_DOMAIN)
pMod = api.PROTOCOL_MODULES[authData.mpModel]
reqMsg = pMod.Message()
pMod.apiMessage.setDefaults(reqMsg)
pMod.apiMessage.setCommunity(reqMsg, authData.communityName)
pMod.apiMessage.setPDU(reqMsg, reqPdu)
outgoingMsg = encoder.encode(reqMsg)
requestId = pMod.apiPDU.getRequestID(reqPdu)
self._pendingReqs[requestId] = dict(
outgoingMsg=outgoingMsg,
transportTarget=transportTarget,
cbFun=cbFun, cbCtx=cbCtx,
timestamp=time() + transportTarget.timeout, retries=0
)
self.transportDispatcher.sendMessage(
outgoingMsg, transportTarget.TRANSPORT_DOMAIN, transportTarget.transportAddr
)
if (reqPdu.__class__ is getattr(pMod, 'SNMPv2TrapPDU', None) or
reqPdu.__class__ is getattr(pMod, 'TrapPDU', None)):
return requestId
self.transportDispatcher.jobStarted(id(self))
return requestId
def _recvCb(self, snmpEngine, transportDomain, transportAddress, wholeMsg):
try:
mpModel = verdec.decodeMessageVersion(wholeMsg)
except error.ProtocolError:
return null # n.b the whole buffer gets dropped
debug.logger & debug.FLAG_DSP and debug.logger('receiveMessage: msgVersion %s, msg decoded' % mpModel)
pMod = api.PROTOCOL_MODULES[mpModel]
while wholeMsg:
rspMsg, wholeMsg = decoder.decode(wholeMsg, asn1Spec=pMod.Message())
rspPdu = pMod.apiMessage.getPDU(rspMsg)
requestId = pMod.apiPDU.getRequestID(rspPdu)
try:
stateInfo = self._pendingReqs.pop(requestId)
except KeyError:
continue
self.transportDispatcher.jobFinished(id(self))
cbFun = stateInfo['cbFun']
cbCtx = stateInfo['cbCtx']
if cbFun:
cbFun(self, requestId, None, rspPdu, cbCtx)
return wholeMsg
def _timerCb(self, timeNow):
for requestId, stateInfo in tuple(self._pendingReqs.items()):
if stateInfo['timestamp'] > timeNow:
continue
retries = stateInfo['retries']
transportTarget = stateInfo['transportTarget']
if retries == transportTarget.retries:
cbFun = stateInfo['cbFun']
cbCtx = stateInfo['cbCtx']
if cbFun:
del self._pendingReqs[requestId]
cbFun(self, requestId, 'Request #%d timed out' % requestId, None, cbCtx)
self.transportDispatcher.jobFinished(id(self))
continue
stateInfo['retries'] += 1
stateInfo['timestamp'] = timeNow + transportTarget.timeout
outgoingMsg = stateInfo['outgoingMsg']
self.transportDispatcher.sendMessage(
outgoingMsg, transportTarget.TRANSPORT_DOMAIN, transportTarget.transportAddr
)
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