def test_parse_ns_question(self):
expected = DnsPacket(id_=2,
is_authoritative=False,
is_response=False,
opcode=0,
is_truncated=False,
is_recursion_desired=True,
is_recursion_available=False,
question=(b'e1.ru', QueryType.NS),
answers=(),
has_error=False)
self._test_packet(expected, 1)
def test_parse_ptr_question(self):
expected = DnsPacket(id_=1,
is_authoritative=False,
is_response=False,
opcode=0,
is_truncated=False,
is_recursion_desired=True,
is_recursion_available=False,
question=(b'1.1.168.192.in-addr.arpa',
QueryType.PTR),
answers=(),
has_error=False)
self._test_packet(expected, 0)
def _test_packet(self, expected, index):
packet = DnsPacket.from_bytes(DnsPacketTest.packets[index])
self.assertEqual(packet.id, expected.id)
self.assertEqual(packet.has_error, expected.has_error)
self.assertEqual(packet.is_authoritative, expected.is_authoritative)
self.assertEqual(packet.is_recursion_desired,
expected.is_recursion_desired)
self.assertEqual(packet.is_recursion_available,
expected.is_recursion_available)
self.assertEqual(packet.is_response, expected.is_response)
self.assertEqual(packet.is_truncated, expected.is_truncated)
self.assertEqual(packet.opcode, expected.opcode)
self.assertEqual(packet.question, expected.question)
self.assertEqual(packet.answers, expected.answers)
def test_parse_ns_answers(self):
answers = [(b'e1.ru', QueryType.NS, 300, b'\x03ns2\x03ngs\xc0\x0f'),
(b'e1.ru', QueryType.NS, 300, b"\x02ns\xc0'"),
(b'e1.ru', QueryType.NS, 300, b'\x03ns1\xc0\x0c'),
(b'e1.ru', QueryType.NS, 300, b'\x03ns2\xc0\x0c')]
expected = DnsPacket(id_=2,
is_authoritative=False,
is_response=True,
opcode=0,
is_truncated=False,
is_recursion_available=True,
is_recursion_desired=True,
question=(b'e1.ru', QueryType.NS),
answers=tuple(answers),
has_error=False)
self._test_packet(expected, 2)
def on_connection(self, sock, data, addr):
try:
print('>> Data received')
packet = DnsPacket.from_bytes(data)
name, query_type = packet.question
print('>> Question: ', query_type, name)
cache_key = int(query_type), name
if cache_key in self.cache:
print('>> Found fresh record in cache')
sock.sendto(self.cache[cache_key], addr)
else:
print('>> No fresh record in cache')
origin_packet = self.forward_question(packet)
if not origin_packet.answers:
print('>> Origin has no answers')
return
min_ttl = min(origin_packet.answers, key=lambda x: x[2])[2]
self.cache.add(cache_key, bytes(origin_packet), min_ttl)
sock.sendto(bytes(origin_packet), addr)
print('>> Answered')
except:
print('>> Error with packet: {}\n{}'.format(
repr(data), format_exc()))
def forward_question(self, packet):
sock = socket(AF_INET, SOCK_DGRAM)
sock.settimeout(12)
sock.sendto(bytes(packet), self.origin)
data, addr = sock.recvfrom(4096)
return DnsPacket.from_bytes(data)
def test_serialize(self):
for packet in DnsPacketTest.packets:
parsed = DnsPacket.from_bytes(packet)
serialized = bytes(parsed)
self.assertEqual(serialized, packet)
def test_serialize_ptr_question(self):
packet = DnsPacketTest.packets[0]
parsed = DnsPacket.from_bytes(packet)
serialized = bytes(parsed)
self.assertEqual(len(serialized), len(packet))
self.assertEqual(serialized, packet)