def parse_buffer(self, length):
import random
import pyvesc.packet.codec as vesc_packet
correct_payload_index = None
if length < 256:
correct_payload_index = 2
else:
correct_payload_index = 3
test_payload = bytes(random.getrandbits(8) for i in range(length))
packet = vesc_packet.frame(test_payload)
# test on small buffers
for n in range(0, 5):
in_buffer = bytearray(packet[:n])
parsed, consumed = vesc_packet.unframe(in_buffer)
out_buffer = in_buffer[consumed:]
self.assertEqual(parsed, None)
self.assertEqual(in_buffer, out_buffer)
# test on buffer almost big enough
for n in range(len(packet) - 4, len(packet)):
in_buffer = bytearray(packet[:n])
parsed, consumed = vesc_packet.unframe(in_buffer)
out_buffer = in_buffer[consumed:]
self.assertEqual(parsed, None)
self.assertEqual(in_buffer, out_buffer)
# test on buffer slightly too big
extension = b'\x02\x04\x07'
extended_packet = packet + b'\x02\x04\x07'
for n in range(len(packet) + 1, len(packet) + 4):
in_buffer = bytearray(extended_packet[:n])
parsed, consumed = vesc_packet.unframe(in_buffer)
out_buffer = in_buffer[consumed:]
self.assertEqual(parsed, test_payload)
self.assertEqual(out_buffer, extension[:n - len(packet)])
def test_corrupt_recovery(self):
import pyvesc.packet.codec as vesc_packet
# make a good packet
test_payload = b'Te!'
good_packet = b'\x02\x03Te!B\x92\x03'
packet_to_recover = b'\x02\x04!\xe1$ 8\xbb\x03' # goal is to recover this packet
payload_to_recover = b'!\xe1$ '
after_goal = b'\x05\x09\x01' # mimic another corrupt packet after
corrupt_packets = []
# corrupt first byte
corrupt = b'\x01\x03Te!B\x92\x03'
corrupt_packets.append(corrupt + packet_to_recover + after_goal)
# corrupt payload_length (to be smaller and larger)
smaller_corrupt = b'\x02\x02Te!B\x92\x03'
larger_corrupt = b'\x02\x04Te!B\x92\x03\x03'
corrupt_packets.append(smaller_corrupt + packet_to_recover +
after_goal)
corrupt_packets.append(larger_corrupt + packet_to_recover + after_goal)
# corrupt first byte in payload
corrupt = b'\x02\x03se!B\x92\x03'
corrupt_packets.append(corrupt + packet_to_recover + after_goal)
# corrupt last byte in payload
corrupt = b'\x02\x03TeyB\x92\x03'
corrupt_packets.append(corrupt + packet_to_recover + after_goal)
# corrupt crc
corrupt = b'\x02\x03Te!\xaa\x91\x03'
corrupt_packets.append(corrupt + packet_to_recover + after_goal)
# corrupt terminator
corrupt = b'\x02\x03Te!B\x92\x09'
corrupt_packets.append(corrupt + packet_to_recover + after_goal)
# check that exceptions are given on each corrupt packet
for corrupt in corrupt_packets:
in_buffer = bytearray(corrupt)
parsed, consumed = vesc_packet.unframe(in_buffer)
out_buffer = in_buffer[consumed:]
self.assertEqual(parsed, payload_to_recover)
found_packet_start = corrupt.find(packet_to_recover)
self.assertTrue(consumed == (found_packet_start +
len(packet_to_recover)))
# check that the good packet is parsed
in_buffer = bytearray(good_packet)
parsed, consumed = vesc_packet.unframe(in_buffer)
out_buffer = in_buffer[consumed:]
self.assertEqual(parsed, test_payload)
self.assertEqual(out_buffer, b'')
def test_corrupt_detection(self):
import pyvesc.packet.codec as vesc_packet
# make a good packet
test_payload = b'Te!'
good_packet = b'\x02\x03Te!B\x92\x03'
corrupt_packets = []
# corrupt first byte
corrupt = b'\x01\x03Te!B\x92\x03'
corrupt_packets.append(corrupt)
# corrupt payload_length (to be smaller and larger)
smaller_corrupt = b'\x02\x02Te!B\x92\x03'
larger_corrupt = b'\x02\x04Te!B\x92\x03\x03'
corrupt_packets.append(smaller_corrupt)
corrupt_packets.append(larger_corrupt)
# corrupt first byte in payload
corrupt = b'\x02\x03se!B\x92\x03'
corrupt_packets.append(corrupt)
# corrupt last byte in payload
corrupt = b'\x02\x03TeyB\x92\x03'
corrupt_packets.append(corrupt)
# corrupt crc
corrupt = b'\x02\x03Te!\xaa\x91\x03'
corrupt_packets.append(corrupt)
# corrupt terminator
corrupt = b'\x02\x03Te!B\x92\x09'
corrupt_packets.append(corrupt)
# check that exceptions are given on each corrupt packet
for corrupt in corrupt_packets:
in_buffer = bytearray(corrupt)
parsed, consumed = vesc_packet.unframe(in_buffer)
out_buffer = in_buffer[consumed:]
self.assertEqual(parsed, None)
self.assertTrue(
consumed > 0
) # if a packet is corrupt then at least something should be consumed
# get correct out_cuffer (in all of these cases it is just consuming to the next valid start byte (no more no less)
self.assertEqual(
consumed,
vesc_packet.Stateless._next_possible_packet_index(in_buffer))
# check that the good packet is parsed
in_buffer = bytearray(good_packet)
parsed, consumed = vesc_packet.unframe(in_buffer)
out_buffer = in_buffer[consumed:]
self.assertEqual(parsed, test_payload)
self.assertEqual(out_buffer, b'')
def exact_two_frames(self, length1, length2):
"""
Check that if there is more than one packet in a buffer, that the unpacker will properly unpack the packets.
Size of buffer for this test is exactly two packets.
:param length1: Length of first payload
:param length2: Length of second payload
"""
import random
import pyvesc.packet.codec as vesc_packet
correct_payload_index1 = None
correct_payload_index2 = None
if length1 < 256:
correct_payload_index1 = 2
else:
correct_payload_index1 = 3
if length2 < 256:
correct_payload_index2 = 2
else:
correct_payload_index2 = 3
test_payload1 = bytes(random.getrandbits(8) for i in range(length1))
test_payload2 = bytes(random.getrandbits(8) for i in range(length2))
# test framing
packet1 = vesc_packet.frame(test_payload1)
packet2 = vesc_packet.frame(test_payload2)
self.assertEqual(len(packet1), correct_payload_index1 + length1 + 3,
"size of packet")
self.assertEqual(len(packet2), correct_payload_index2 + length2 + 3,
"size of packet")
buffer = bytearray(packet1 + packet2)
# test Parser
parsed, consumed = vesc_packet.unframe(buffer)
buffer = buffer[consumed:]
self.assertEqual(parsed, test_payload1)
self.assertEqual(len(buffer), len(packet2))
parsed, consumed = vesc_packet.unframe(buffer)
buffer = buffer[consumed:]
self.assertEqual(parsed, test_payload2)
self.assertEqual(len(buffer), 0)
def exact_single_frame(self, length):
"""
Simplest test possible. Create a packet, then parse a buffer containing this packet. Size of buffer is exactly
one packet (no excess).
:param length: Number of bytes in payload.
"""
import random
import pyvesc.packet.codec as vesc_packet
correct_payload_index = None
if length < 256:
correct_payload_index = 2
else:
correct_payload_index = 3
test_payload = bytes(random.getrandbits(8) for i in range(length))
# test framing
packet = vesc_packet.frame(test_payload)
self.assertEqual(len(packet), correct_payload_index + length + 3,
"size of packet")
buffer = bytearray(packet)
# test Parser
parsed, consumed = vesc_packet.unframe(buffer)
buffer = buffer[consumed:]
self.assertEqual(parsed, test_payload)
self.assertEqual(len(buffer), 0)