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|
"""
Implementing scalar MIB objects
+++++++++++++++++++++++++++++++
Listen and respond to SNMP GET/GETNEXT queries with the following options:
* SNMPv1 or SNMPv2c
* with SNMP community "public"
* over IPv4/UDP, listening at 127.0.0.1:161
* over IPv6/UDP, listening at [::1]:161
* serving two Managed Objects Instances (sysDescr.0 and sysUptime.0)
Either of the following Net-SNMP commands will walk this Agent:
| $ snmpwalk -v2c -c public 127.0.0.1 .1.3.6
| $ snmpwalk -v2c -c public udp6:[::1] .1.3.6
The Command Receiver below uses two distinct transports for communication
with Command Generators - UDP over IPv4 and UDP over IPv6.
"""#
from pysnmp.carrier.asyncore.dispatch import AsyncoreDispatcher
from pysnmp.carrier.asyncore.dgram import udp, udp6, unix
from pyasn1.codec.ber import encoder, decoder
from pysnmp.proto import api
import time, bisect
class SysDescr(object):
name = (1, 3, 6, 1, 2, 1, 1, 1, 0)
def __eq__(self, other): return self.name == other
def __ne__(self, other): return self.name != other
def __lt__(self, other): return self.name < other
def __le__(self, other): return self.name <= other
def __gt__(self, other): return self.name > other
def __ge__(self, other): return self.name >= other
def __call__(self, protoVer):
return api.protoModules[protoVer].OctetString(
'PySNMP example command responder'
)
class Uptime(object):
name = (1, 3, 6, 1, 2, 1, 1, 3, 0)
birthday = time.time()
def __eq__(self, other): return self.name == other
def __ne__(self, other): return self.name != other
def __lt__(self, other): return self.name < other
def __le__(self, other): return self.name <= other
def __gt__(self, other): return self.name > other
def __ge__(self, other): return self.name >= other
def __call__(self, protoVer):
return api.protoModules[protoVer].TimeTicks(
(time.time() - self.birthday) * 100
)
mibInstr = (
SysDescr(), Uptime() # sorted by object name
)
mibInstrIdx = {}
for mibVar in mibInstr:
mibInstrIdx[mibVar.name] = mibVar
def cbFun(transportDispatcher, transportDomain, transportAddress, wholeMsg):
while wholeMsg:
msgVer = api.decodeMessageVersion(wholeMsg)
if msgVer in api.protoModules:
pMod = api.protoModules[msgVer]
else:
print('Unsupported SNMP version %s' % msgVer)
return
reqMsg, wholeMsg = decoder.decode(
wholeMsg, asn1Spec=pMod.Message(),
)
rspMsg = pMod.apiMessage.getResponse(reqMsg)
rspPDU = pMod.apiMessage.getPDU(rspMsg)
reqPDU = pMod.apiMessage.getPDU(reqMsg)
varBinds = []
pendingErrors = []
errorIndex = 0
# GETNEXT PDU
if reqPDU.isSameTypeWith(pMod.GetNextRequestPDU()):
# Produce response var-binds
for oid, val in pMod.apiPDU.getVarBinds(reqPDU):
errorIndex = errorIndex + 1
# Search next OID to report
nextIdx = bisect.bisect(mibInstr, oid)
if nextIdx == len(mibInstr):
# Out of MIB
varBinds.append((oid, val))
pendingErrors.append(
(pMod.apiPDU.setEndOfMibError, errorIndex)
)
else:
# Report value if OID is found
varBinds.append(
(mibInstr[nextIdx].name, mibInstr[nextIdx](msgVer))
)
elif reqPDU.isSameTypeWith(pMod.GetRequestPDU()):
for oid, val in pMod.apiPDU.getVarBinds(reqPDU):
if oid in mibInstrIdx:
varBinds.append((oid, mibInstrIdx[oid](msgVer)))
else:
# No such instance
varBinds.append((oid, val))
pendingErrors.append(
(pMod.apiPDU.setNoSuchInstanceError, errorIndex)
)
break
else:
# Report unsupported request type
pMod.apiPDU.setErrorStatus(rspPDU, 'genErr')
pMod.apiPDU.setVarBinds(rspPDU, varBinds)
# Commit possible error indices to response PDU
for f, i in pendingErrors:
f(rspPDU, i)
transportDispatcher.sendMessage(
encoder.encode(rspMsg), transportDomain, transportAddress
)
return wholeMsg
transportDispatcher = AsyncoreDispatcher()
transportDispatcher.registerRecvCbFun(cbFun)
# UDP/IPv4
transportDispatcher.registerTransport(
udp.domainName, udp.UdpSocketTransport().openServerMode(('localhost', 161))
)
# UDP/IPv6
transportDispatcher.registerTransport(
udp6.domainName, udp6.Udp6SocketTransport().openServerMode(('::1', 161))
)
## Local domain socket
# transportDispatcher.registerTransport(
# unix.domainName, unix.UnixSocketTransport().openServerMode('/tmp/snmp-agent')
# )
transportDispatcher.jobStarted(1)
try:
# Dispatcher will never finish as job#1 never reaches zero
transportDispatcher.runDispatcher()
except:
transportDispatcher.closeDispatcher()
raise
|
