def walk(self,
host,
starting_oid=None,
port=161,
timeout=10,
max_initial_failures=1,
max_consequtive_failures=3):
"""Walks the MIB from the given starting oid, returns a list of (oid, object) tuples"""
# TODO: perhaps an OrderedDict is more appropriate?
responses = []
attempts_remaining = max_initial_failures
datagram = SNMPDatagram(pdu=GetNextRequest.from_oid(starting_oid))
while attempts_remaining:
future = self.sendto(datagram, host, port)
try:
response = yield from asyncio.wait_for(future, timeout=timeout)
except asyncio.TimeoutError:
logging.debug("Timeout for GetNextRequest(%s, %s)", host,
datagram.pdu.oid)
if isinstance(attempts_remaining, int):
attempts_remaining -= 1
else:
assert isinstance(response.pdu, GetResponse)
attempts_remaining = max_consequtive_failures
logging.debug("Response from host %s: %s=%s", host,
response.pdu.oid, response.pdu.response)
if datagram.pdu.oid == response.pdu.oid:
# end of mib condition
break
else:
responses.append((response.pdu.oid, response.pdu.response))
pdu = GetNextRequest.from_oid(response.pdu.oid)
datagram = SNMPDatagram(pdu=pdu)
# else:
# raise ExceededRetries('Maximum retries exceeded')
return responses
def datagram_received(self, datagram, addr):
(host, port) = addr
try:
datagram = SNMPDatagram.decode(datagram)
except:
print("Malformed packet from:", host, binascii.hexlify(bytes(datagram)))
else:
# TODO: implement object comparison/equivalence testing
key = (host, datagram.pdu.request_id.value)
if key in self.requests:
try:
self.requests[key].set_result(datagram)
except asyncio.InvalidStateError:
del self.requests[key]
else:
logging.debug("Unexpected SNMP datagram from %s: %s.", host, datagram)
logging.debug("%s", self.requests)
def test_decode(self):
snmp_datagrams = list(map(binascii.a2b_hex,
['302602010004067075626c6963a119020452447053020100020100300b300906052b060102010500',
'307902010004067075626c6963a26c020452447053020100020100305e305c06082b0601020101010004504c696e7578206e696e6a616c6170707920342e322e352d312d4152434820233120534d5020505245454d505420547565204f63742032372030383a31333a3238204345542032303135207838365f3634',
'302902010004067075626c6963a11c020452447054020100020100300e300c06082b060102010101000500',
'303302010004067075626c6963a2260204524470540201000201003018301606082b06010201010200060a2b06010401bf0803020a']))
for datagram in snmp_datagrams:
print(binascii.hexlify(datagram))
decoded = SNMPDatagram.decode(datagram)
print(decoded)
encoded = bytes(decoded)
print(binascii.hexlify(encoded))
# TODO: __cmp__ or __hash__ perhaps
# Not always true for BER
# DER uses a canonical form, eg: representation of booleans, and ambiguous length encodings
# assert encoded == datagram
self.assertEqual(datagram, encoded)
def datagram_received(self, datagram, addr):
(host, port) = addr
try:
datagram = SNMPDatagram.decode(datagram)
except:
print("Malformed packet from:", host,
binascii.hexlify(bytes(datagram)))
else:
# TODO: implement object comparison/equivalence testing
key = (host, datagram.pdu.request_id.value)
if key in self.requests:
try:
self.requests[key].set_result(datagram)
except asyncio.InvalidStateError:
del self.requests[key]
else:
logging.debug("Unexpected SNMP datagram from %s: %s.", host,
datagram)
logging.debug("%s", self.requests)
def get_next(self, host, oid=system, port=161):
"""Creates GetNextResponse PDU / datagram and returns a Future"""
pdu = GetNextRequest.from_oid(oid)
datagram = SNMPDatagram(pdu=pdu)
return self.sendto(datagram, host, port)
