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confluent/confluent_server/confluent/snmputil.py
Jarrod Johnson a0ca3d3122 Extend snmp timeout
Default is 1 second, bump to 2 seconds for some
extraordinarily slow switches.  This changes
overall to about 10 seconds as there are, by default,
5 retries.
2021-10-07 13:03:05 -04:00

125 lines
4.9 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2016 Lenovo
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# This provides a simplified wrapper around snmp implementation roughly
# mapping to the net-snmp commands
# net-snmp-python was considered as the API is cleaner, but the ability to
# patch pysnmp to have it be eventlet friendly has caused it's selection
# This module simplifies the complex hlapi pysnmp interface
import confluent.exceptions as exc
import eventlet
from eventlet.support.greendns import getaddrinfo
import pysnmp.smi.error as snmperr
import socket
snmp = eventlet.import_patched('pysnmp.hlapi')
def _get_transport(name):
# Annoyingly, pysnmp does not automatically determine ipv6 v ipv4
res = getaddrinfo(name, 161, 0, socket.SOCK_DGRAM)
if res[0][0] == socket.AF_INET6:
return snmp.Udp6TransportTarget(res[0][4], 2)
else:
return snmp.UdpTransportTarget(res[0][4], 2)
class Session(object):
def __init__(self, server, secret, username=None, context=None):
"""Create a new session to interrogate a switch
If username is not given, it is assumed that
the secret is community string, and v2c is used. If a username given,
it'll assume SHA auth and DES privacy with the secret being the same
for both.
:param server: The network name/address to target
:param secret: The community string or password
:param username: The username for SNMPv3
:param context: The SNMPv3 context or index for community indexing
"""
self.server = server
self.context = context
if username is None:
# SNMP v2c
self.authdata = snmp.CommunityData(secret, mpModel=1)
else:
self.authdata = snmp.UsmUserData(
username, authKey=secret, privKey=secret,
authProtocol=snmp.usmHMACSHAAuthProtocol)
self.eng = snmp.SnmpEngine()
def walk(self, oid):
"""Walk over children of a given OID
This is roughly equivalent to snmpwalk. It will automatically try to
be a snmpbulkwalk if possible.
:param oid: The SNMP object identifier
"""
# SNMP is a complicated mess of things. Will endeavor to shield caller
# from as much as possible, assuming reasonable defaults when possible.
# there may come a time where we add more parameters to override the
# automatic behavior (e.g. DES is weak, so it's likely to be
# overriden, but some devices only support DES)
tp = _get_transport(self.server)
ctx = snmp.ContextData(self.context)
resolvemib = False
if '::' in oid:
resolvemib = True
mib, field = oid.split('::')
obj = snmp.ObjectType(snmp.ObjectIdentity(mib, field))
else:
obj = snmp.ObjectType(snmp.ObjectIdentity(oid))
walking = snmp.bulkCmd(self.eng, self.authdata, tp, ctx, 0, 10, obj,
lexicographicMode=False, lookupMib=resolvemib)
try:
for rsp in walking:
errstr, errnum, erridx, answers = rsp
if errstr:
errstr = str(errstr)
finerr = errstr + ' while trying to connect to ' \
'{0}'.format(self.server)
if errstr in ('Unknown USM user', 'unknownUserName',
'wrongDigest', 'Wrong SNMP PDU digest'):
raise exc.TargetEndpointBadCredentials(finerr)
# need to do bad credential versus timeout
raise exc.TargetEndpointUnreachable(finerr)
elif errnum:
raise exc.ConfluentException(errnum.prettyPrint() +
' while trying to connect to '
'{0}'.format(self.server))
for ans in answers:
if not obj[0].isPrefixOf(ans[0]):
# PySNMP returns leftovers in a bulk command
# filter out such leftovers
break
yield ans
except snmperr.WrongValueError:
raise exc.TargetEndpointBadCredentials('Invalid SNMPv3 password')
if __name__ == '__main__':
import sys
ts = Session(sys.argv[1], 'public')
for kp in ts.walk(sys.argv[2]):
print(str(kp[0]))
print(str(kp[1]))