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# SNMP v1 & v2c security models implementation
from pyasn1.codec.ber import encoder
from pysnmp.proto.secmod import base
from pysnmp.smi.error import NoSuchInstanceError
from pysnmp.proto import error
class SnmpV1SecurityModel(base.AbstractSecurityModel):
securityModelID = 1
# According to rfc2576, community name <-> contextEngineId/contextName
# mapping is up to MP module for notifications but belongs to secmod
# responsibility for other PDU types. Since I do not yet understand
# the reason for this de-coupling, I've moved this code from MP-scope
# in here.
def generateRequestMsg(
self,
snmpEngine,
messageProcessingModel,
globalData,
maxMessageSize,
securityModel,
securityEngineId,
securityName,
securityLevel,
scopedPDU
):
msg, = globalData
contextEngineId, contextName, pdu = scopedPDU
# rfc2576: 5.2.3
( snmpCommunityName,
snmpCommunitySecurityName,
snmpCommunityContextEngineId,
snmpCommunityContextName ) = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols(
'SNMP-COMMUNITY-MIB',
'snmpCommunityName',
'snmpCommunitySecurityName',
'snmpCommunityContextEngineID',
'snmpCommunityContextName'
)
mibNodeIdx = snmpCommunitySecurityName
while 1:
try:
mibNodeIdx = snmpCommunitySecurityName.getNextNode(
mibNodeIdx.name
)
except NoSuchInstanceError:
break
if mibNodeIdx.syntax != securityName:
continue
instId = mibNodeIdx.name[len(snmpCommunitySecurityName.name):]
mibNode = snmpCommunityContextEngineId.getNode(
snmpCommunityContextEngineId.name + instId
)
if mibNode.syntax != contextEngineId:
continue
mibNode = snmpCommunityContextName.getNode(
snmpCommunityContextName.name + instId
)
if mibNode.syntax != contextName:
continue
# XXX TODO: snmpCommunityTransportTag
mibNode = snmpCommunityName.getNode(
snmpCommunityName.name + instId
)
securityParameters = mibNode.syntax
msg.setComponentByPosition(1, securityParameters)
msg.setComponentByPosition(2)
msg.getComponentByPosition(2).setComponentByType(pdu.tagSet, pdu)
wholeMsg = encoder.encode(msg)
return ( securityParameters, wholeMsg )
raise error.StatusInformation(
errorIndication = 'unknownCommunityName'
)
def generateResponseMsg(
self,
snmpEngine,
messageProcessingModel,
globalData,
maxMessageSize,
securityModel,
securityEngineID,
securityName,
securityLevel,
scopedPDU,
securityStateReference
):
# rfc2576: 5.2.2
msg, = globalData
contextEngineId, contextName, pdu = scopedPDU
cachedSecurityData = self._cachePop(securityStateReference)
communityName = cachedSecurityData['communityName']
msg.setComponentByPosition(1, communityName)
msg.setComponentByPosition(2)
msg.getComponentByPosition(2).setComponentByType(pdu.tagSet, pdu)
wholeMsg = encoder.encode(msg)
return ( communityName, wholeMsg )
def processIncomingMsg(
self,
snmpEngine,
messageProcessingModel,
maxMessageSize,
securityParameters,
securityModel,
securityLevel,
wholeMsg,
msg
):
# rfc2576: 5.2.1
( communityName, srcTransport, destTransport ) = securityParameters
( snmpCommunityName,
snmpCommunitySecurityName,
snmpCommunityContextEngineId,
snmpCommunityContextName
) = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols(
'SNMP-COMMUNITY-MIB',
'snmpCommunityName',
'snmpCommunitySecurityName',
'snmpCommunityContextEngineID',
'snmpCommunityContextName'
)
mibNodeIdx = snmpCommunityName
while 1:
try:
mibNodeIdx = snmpCommunityName.getNextNode(
mibNodeIdx.name
)
except NoSuchInstanceError:
break
if mibNodeIdx.syntax != communityName:
continue
break
else:
snmpInBadCommunityNames, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-COMMUNITY-MIB', 'snmpInBadCommunityNames')
snmpInBadCommunityNames.syntax = snmpInBadCommunityNames.syntax+1
raise error.StatusInformation(
errorIndication = 'unknownCommunityName'
)
# XXX TODO: snmpCommunityTransportTag
instId = mibNodeIdx.name[len(snmpCommunityName.name):]
communityName = snmpCommunityName.getNode(
snmpCommunityName.name + instId
)
securityName = snmpCommunitySecurityName.getNode(
snmpCommunitySecurityName.name + instId
)
contextEngineId = snmpCommunityContextEngineId.getNode(
snmpCommunityContextEngineId.name + instId
)
contextName = snmpCommunityContextName.getNode(
snmpCommunityContextName.name + instId
)
snmpEngineID, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-FRAMEWORK-MIB', 'snmpEngineID')
stateReference = self._cachePush(
communityName=communityName.syntax
)
securityEngineID = snmpEngineID.syntax
securityName = securityName.syntax
scopedPDU = (
contextEngineId.syntax, contextName.syntax,
msg.getComponentByPosition(2).getComponent()
)
maxSizeResponseScopedPDU = maxMessageSize - 128
securityStateReference = stateReference
return ( securityEngineID,
securityName,
scopedPDU,
maxSizeResponseScopedPDU,
securityStateReference )
class SnmpV2cSecurityModel(SnmpV1SecurityModel):
securityModelID = 2
# XXX
# contextEngineId/contextName goes to globalData
|
