def test_get_data_fragment_2_fragments():
udp_payload = get_random_bytes(400)
fragmented_payload = bytes()
f = FragmentGenerator(udp_payload)
fragment = f.get_data_fragment()
msg_id, is_last, fragment_id, payload = parse_fragment(fragment)
fragmented_payload += payload
assert msg_id == f.message_id
assert not is_last
assert fragment_id == 0
fragment = f.get_data_fragment()
msg_id, is_last, fragment_id, payload = parse_fragment(fragment)
fragmented_payload += payload
assert msg_id == f.message_id
assert is_last
assert fragment_id == 1
assert udp_payload == fragmented_payload
def test_get_data_fragment_too_many():
udp_payload = get_random_bytes(400)
f = FragmentGenerator(udp_payload)
try:
for _ in range(1000):
f.get_data_fragment()
assert False
except ValueError:
assert True
def test_get_init_fragment():
udp_payload = get_random_bytes(120)
f = FragmentGenerator(udp_payload)
fragment = f.get_init_fragment()
msg_id, is_last, fragment_id, payload = parse_fragment(fragment)
assert msg_id == f.message_id
assert is_last
assert fragment_id == 0
assert udp_payload == payload
def recv_response(self, response):
self.last_interaction = time()
"""Turns the response into a MixMessage and saves its fragments for
later sending.
"""
frag_gen = FragmentGenerator(response)
while frag_gen:
print(self, "Data", "<-", len(frag_gen.udp_payload))
fragment = frag_gen.get_data_fragment()
packet = fragment + get_random_bytes(MIX_COUNT * CTR_PREFIX_LEN)
ChannelExit.to_mix.append(DATA_MSG_FLAG + i2b(self.in_chan_id, CHAN_ID_SIZE) + packet)
def test_get_data_fragment():
udp_payload = get_random_bytes(DATA_FRAG_PAYLOAD_SIZE)
f = FragmentGenerator(udp_payload)
fragment = f.get_data_fragment()
_, frag_byte, payload = cut(fragment, FRAG_ID_SIZE, FRAG_FLAG_SIZE)
assert b2i(frag_byte) & FragmentGenerator.LAST_FRAG_FLAG
assert b2i(frag_byte) == 0b0100_0000
assert payload[0:DATA_FRAG_PAYLOAD_SIZE] == udp_payload
assert len(
fragment) == DATA_FRAG_PAYLOAD_SIZE + FRAG_ID_SIZE + FRAG_FLAG_SIZE
def _make_request_fragments(self, request):
generator = FragmentGenerator(request)
self.packets.append(generator)
timed_out = check_for_timed_out_channels(ChannelEntry.table, timeout=25)
for channel_id in timed_out:
del ChannelEntry.table[channel_id]
def test_get_data_fragment_with_padding():
udp_payload = get_random_bytes(DATA_FRAG_PAYLOAD_SIZE - 1)
f = FragmentGenerator(udp_payload)
fragment = f.get_data_fragment()
_, frag_byte, _, payload = cut(fragment, FRAG_ID_SIZE, FRAG_FLAG_SIZE, 1)
assert b2i(frag_byte) & FragmentGenerator.LAST_FRAG_FLAG
assert b2i(frag_byte) & FragmentGenerator.PADDING_FLAG
assert b2i(frag_byte) == 0b1100_0000
assert payload[0:DATA_FRAG_PAYLOAD_SIZE - 1] == udp_payload
assert len(
fragment) == DATA_FRAG_PAYLOAD_SIZE + FRAG_ID_SIZE + FRAG_FLAG_SIZE
udp_payload = get_random_bytes(1)
f = FragmentGenerator(udp_payload)
fragment = f.get_data_fragment()
_, frag_byte, _, payload = cut(fragment, FRAG_ID_SIZE, FRAG_FLAG_SIZE, 2)
assert b2i(frag_byte) & FragmentGenerator.LAST_FRAG_FLAG
assert b2i(frag_byte) & FragmentGenerator.PADDING_FLAG
assert b2i(frag_byte) == 0b1100_0000
assert payload[0:1] == udp_payload
assert len(
fragment) == DATA_FRAG_PAYLOAD_SIZE + FRAG_ID_SIZE + FRAG_FLAG_SIZE
def test_encrypt_fragment():
channel = ChannelEntry(src_addr, dest_addr, public_keys)
sym_key = gen_sym_key()
channel.sym_keys = [sym_key] * MIX_COUNT
fragment = FragmentGenerator(bytes(100)).get_data_fragment()
packet1 = channel._encrypt_fragment(fragment)
packet2 = fragment
counter = 1
for _ in range(MIX_COUNT):
cipher = ctr_cipher(sym_key, counter)
packet2 = i2b(counter, CTR_PREFIX_LEN) + cipher.encrypt(packet2)
assert packet1 == packet2
def test_decrypt_fragment():
channel = ChannelEntry(src_addr, dest_addr, public_keys)
sym_key = gen_sym_key()
channel.sym_keys = [sym_key] * MIX_COUNT
fragment = FragmentGenerator(bytes(100)).get_data_fragment()
fragment = channel._encrypt_fragment(fragment)
packet1 = channel._decrypt_fragment(fragment)
for _ in range(MIX_COUNT):
msg_ctr, fragment = cut(fragment, CTR_PREFIX_LEN)
cipher = ctr_cipher(sym_key, b2i(msg_ctr))
fragment = cipher.decrypt(fragment)
packet2 = fragment
assert packet1 == packet2
def test_replay_detection():
channel = ChannelEntry(src_addr, dest_addr, public_keys)
counter = 1234
sym_key = gen_sym_key()
channel.sym_keys = [sym_key] * MIX_COUNT
print("Counter: {}".format(counter))
packet = FragmentGenerator(bytes(100)).get_data_fragment()
packet = channel._encrypt_fragment(packet)
channel._receive_response_fragment(packet)
try:
channel._receive_response_fragment(packet)
assert False
except ReplayDetectedError:
assert True
packet = channel._encrypt_fragment(packet)
channel._receive_response_fragment(packet)