"""
SNMPv2c
+++++++

Send SNMP GET request using the following options:

  * with SNMPv2c, community 'public'
  * over IPv4/UDP with non-default timeout and no retries
  * to an Agent at demo.snmplabs.com:161
  * for two instances of SNMPv2-MIB::sysDescr.0 MIB object,
  * based on Twisted I/O framework

Functionally similar to:

| $ snmpget -v2c -c public -r 0 -t 2 demo.snmplabs.com SNMPv2-MIB::sysDescr.0

"""#
from twisted.internet.task import react
from pysnmp.hlapi.v3arch.twisted import *


def success(args, hostname):
    errorStatus, errorIndex, varBinds = args

    if errorStatus:
        print('%s: %s at %s' % (hostname,
                                errorStatus.prettyPrint(),
                                errorIndex and varBinds[int(errorIndex) - 1][0] or '?')) 

    else:
        for varBind in varBinds:
            print(' = '.join([x.prettyPrint() for x in varBind]))


def failure(errorIndication, hostname):
    print('%s failure: %s' % (hostname, errorIndication))


# noinspection PyUnusedLocal
def getSysDescr(reactor, hostname):

    snmpEngine = SnmpEngine()

    deferred = getCmd(
        snmpEngine,
        CommunityData('public'),
        UdpTransportTarget((hostname, 161), timeout=2.0, retries=0),
        ContextData(),
        ObjectType(ObjectIdentity('SNMPv2-MIB', 'sysDescr', 0))
    )

    deferred.addCallback(success, hostname).addErrback(failure, hostname)

    return deferred


react(getSysDescr, ['demo.snmplabs.com'])
