[tor-commits] [stem/master] Cell attribute for unused padding
atagar at torproject.org
atagar at torproject.org
Mon Jun 18 20:10:28 UTC 2018
commit 84e4e657b4785e4888e567fbc04c8ea29fd43cc4
Author: Damian Johnson <atagar at torproject.org>
Date: Mon Jun 18 13:02:47 2018 -0700
Cell attribute for unused padding
I love our prior commit's effort to be more explicit when Cell data is
explicitly ignored. Rather than a commment making this an 'unused' attribute of
the base Cell class. This way our callers will have all the information
necessary to reconstruct cells if they so desire.
---
stem/client/cell.py | 67 ++++++++++++++++++++++++++++++++++--------------
test/unit/client/cell.py | 6 +++++
2 files changed, 54 insertions(+), 19 deletions(-)
diff --git a/stem/client/cell.py b/stem/client/cell.py
index 1b30db6c..788c4c41 100644
--- a/stem/client/cell.py
+++ b/stem/client/cell.py
@@ -75,12 +75,18 @@ STREAM_ID_DISALLOWED = (
class Cell(object):
"""
Metadata for ORPort cells.
+
+ :var bytes unused: unused filler that padded the cell to the expected size
"""
NAME = 'UNKNOWN'
VALUE = -1
IS_FIXED_SIZE = False
+ def __init__(self, unused = b''):
+ super(Cell, self).__init__()
+ self.unused = unused
+
@staticmethod
def by_name(name):
"""
@@ -240,7 +246,8 @@ class CircuitCell(Cell):
:var int circ_id: circuit id
"""
- def __init__(self, circ_id):
+ def __init__(self, circ_id, unused = b''):
+ super(CircuitCell, self).__init__(unused)
self.circ_id = circ_id
@@ -261,6 +268,7 @@ class PaddingCell(Cell):
elif len(payload) != FIXED_PAYLOAD_LEN:
raise ValueError('Padding payload should be %i bytes, but was %i' % (FIXED_PAYLOAD_LEN, len(payload)))
+ super(PaddingCell, self).__init__()
self.payload = payload
def pack(self, link_protocol):
@@ -279,12 +287,18 @@ class CreateCell(CircuitCell):
VALUE = 1
IS_FIXED_SIZE = True
+ def __init__(self):
+ super(CreateCell, self).__init__() # TODO: implement
+
class CreatedCell(CircuitCell):
NAME = 'CREATED'
VALUE = 2
IS_FIXED_SIZE = True
+ def __init__(self):
+ super(CreatedCell, self).__init__() # TODO: implement
+
class RelayCell(CircuitCell):
"""
@@ -302,7 +316,7 @@ class RelayCell(CircuitCell):
VALUE = 3
IS_FIXED_SIZE = True
- def __init__(self, circ_id, command, data, digest = 0, stream_id = 0, recognized = 0):
+ def __init__(self, circ_id, command, data, digest = 0, stream_id = 0, recognized = 0, unused = b''):
if 'HASH' in str(type(digest)):
# Unfortunately hashlib generates from a dynamic private class so
# isinstance() isn't such a great option. With python2/python3 the
@@ -316,7 +330,7 @@ class RelayCell(CircuitCell):
else:
raise ValueError('RELAY cell digest must be a hash, string, or int but was a %s' % type(digest).__name__)
- super(RelayCell, self).__init__(circ_id)
+ super(RelayCell, self).__init__(circ_id, unused)
self.command, self.command_int = RelayCommand.get(command)
self.data = str_tools._to_bytes(data)
self.recognized = recognized
@@ -347,11 +361,9 @@ class RelayCell(CircuitCell):
stream_id, content = Size.SHORT.pop(content)
digest, content = Size.LONG.pop(content)
data_len, content = Size.SHORT.pop(content)
- data, _ = split(content, data_len)
+ data, unused = split(content, data_len)
- # remaining content (if any) is thrown out (ignored)
-
- return RelayCell(circ_id, command, data, digest, stream_id, recognized)
+ return RelayCell(circ_id, command, data, digest, stream_id, recognized, unused)
def __hash__(self):
return _hash_attr(self, 'command_int', 'stream_id', 'digest', 'data')
@@ -481,6 +493,7 @@ class VersionsCell(Cell):
IS_FIXED_SIZE = False
def __init__(self, versions):
+ super(VersionsCell, self).__init__()
self.versions = versions
def pack(self, link_protocol = None):
@@ -517,7 +530,8 @@ class NetinfoCell(Cell):
VALUE = 8
IS_FIXED_SIZE = True
- def __init__(self, receiver_address, sender_addresses, timestamp = None):
+ def __init__(self, receiver_address, sender_addresses, timestamp = None, unused = b''):
+ super(NetinfoCell, self).__init__(unused)
self.timestamp = timestamp if timestamp else datetime.datetime.now()
self.receiver_address = receiver_address
self.sender_addresses = sender_addresses
@@ -548,9 +562,7 @@ class NetinfoCell(Cell):
addr, content = Address.pop(content)
sender_addresses.append(addr)
- # remaining content (if any) is thrown out (ignored)
-
- return NetinfoCell(receiver_address, sender_addresses, datetime.datetime.utcfromtimestamp(timestamp))
+ return NetinfoCell(receiver_address, sender_addresses, datetime.datetime.utcfromtimestamp(timestamp), unused = b'')
def __hash__(self):
return _hash_attr(self, 'timestamp', 'receiver_address', 'sender_addresses')
@@ -561,24 +573,36 @@ class RelayEarlyCell(CircuitCell):
VALUE = 9
IS_FIXED_SIZE = True
+ def __init__(self):
+ super(RelayEarlyCell, self).__init__() # TODO: implement
+
class Create2Cell(CircuitCell):
NAME = 'CREATE2'
VALUE = 10
IS_FIXED_SIZE = True
+ def __init__(self):
+ super(Create2Cell, self).__init__() # TODO: implement
+
class Created2Cell(Cell):
NAME = 'CREATED2'
VALUE = 11
IS_FIXED_SIZE = True
+ def __init__(self):
+ super(Created2Cell, self).__init__() # TODO: implement
+
class PaddingNegotiateCell(Cell):
NAME = 'PADDING_NEGOTIATE'
VALUE = 12
IS_FIXED_SIZE = True
+ def __init__(self):
+ super(PaddingNegotiateCell, self).__init__() # TODO: implement
+
class VPaddingCell(Cell):
"""
@@ -599,6 +623,7 @@ class VPaddingCell(Cell):
elif size is not None and payload is not None and size != len(payload):
raise ValueError('VPaddingCell constructor specified both a size of %i bytes and payload of %i bytes' % (size, len(payload)))
+ super(VPaddingCell, self).__init__()
self.payload = payload if payload is not None else os.urandom(size)
def pack(self, link_protocol):
@@ -623,7 +648,8 @@ class CertsCell(Cell):
VALUE = 129
IS_FIXED_SIZE = False
- def __init__(self, certs):
+ def __init__(self, certs, unused = b''):
+ super(CertsCell, self).__init__(unused)
self.certificates = certs
def pack(self, link_protocol):
@@ -641,9 +667,7 @@ class CertsCell(Cell):
cert, content = Certificate.pop(content)
certs.append(cert)
- # remaining content (if any) is thrown out (ignored)
-
- return CertsCell(certs)
+ return CertsCell(certs, unused = content)
def __hash__(self):
return _hash_attr(self, 'certificates')
@@ -662,12 +686,13 @@ class AuthChallengeCell(Cell):
VALUE = 130
IS_FIXED_SIZE = False
- def __init__(self, methods, challenge = None):
+ def __init__(self, methods, challenge = None, unused = b''):
if not challenge:
challenge = os.urandom(AUTH_CHALLENGE_SIZE)
elif len(challenge) != AUTH_CHALLENGE_SIZE:
raise ValueError('AUTH_CHALLENGE must be %i bytes, but was %i' % (AUTH_CHALLENGE_SIZE, len(challenge)))
+ super(AuthChallengeCell, self).__init__(unused)
self.challenge = challenge
self.methods = methods
@@ -698,9 +723,7 @@ class AuthChallengeCell(Cell):
method, content = Size.SHORT.pop(content)
methods.append(method)
- # remaining content (if any) is thrown out (ignored)
-
- return AuthChallengeCell(methods, challenge)
+ return AuthChallengeCell(methods, challenge, unused = content)
def __hash__(self):
return _hash_attr(self, 'challenge', 'methods')
@@ -711,8 +734,14 @@ class AuthenticateCell(Cell):
VALUE = 131
IS_FIXED_SIZE = False
+ def __init__(self):
+ super(AuthenticateCell, self).__init__() # TODO: implement
+
class AuthorizeCell(Cell):
NAME = 'AUTHORIZE'
VALUE = 132
IS_FIXED_SIZE = False
+
+ def __init__(self):
+ super(AuthorizeCell, self).__init__() # TODO: implement
diff --git a/test/unit/client/cell.py b/test/unit/client/cell.py
index 3d054757..b6734fe7 100644
--- a/test/unit/client/cell.py
+++ b/test/unit/client/cell.py
@@ -173,6 +173,7 @@ class TestCell(unittest.TestCase):
self.assertEqual(data, cell.data)
self.assertEqual(digest, cell.digest)
self.assertEqual(stream_id, cell.stream_id)
+ self.assertEqual(b'\x00' * (498 - len(cell.data)), cell.unused)
digest = hashlib.sha1(b'hi')
self.assertEqual(3257622417, RelayCell(5, 'RELAY_BEGIN_DIR', '', digest, 564346860).digest)
@@ -190,6 +191,7 @@ class TestCell(unittest.TestCase):
self.assertEqual(circ_id, cell.circ_id)
self.assertEqual(reason, cell.reason)
self.assertEqual(reason_int, cell.reason_int)
+ self.assertEqual(b'', cell.unused)
self.assertRaisesRegexp(ValueError, 'Circuit closure reason should be a single byte, but was 2', Cell.pop, b'\x80\x00\x00\x00\x04\x01\x01' + ZERO * 507, 5)
@@ -200,6 +202,7 @@ class TestCell(unittest.TestCase):
cell = Cell.pop(cell_bytes, 5)[0]
self.assertEqual(circ_id, cell.circ_id)
self.assertEqual(key_material, cell.key_material)
+ self.assertEqual(b'', cell.unused)
self.assertRaisesRegexp(ValueError, 'Key material should be 20 bytes, but was 3', CreateFastCell, 5, 'boo')
@@ -211,6 +214,7 @@ class TestCell(unittest.TestCase):
self.assertEqual(circ_id, cell.circ_id)
self.assertEqual(key_material, cell.key_material)
self.assertEqual(derivative_key, cell.derivative_key)
+ self.assertEqual(b'', cell.unused)
self.assertRaisesRegexp(ValueError, 'Key material should be 20 bytes, but was 3', CreateFastCell, 5, 'boo')
@@ -227,6 +231,7 @@ class TestCell(unittest.TestCase):
self.assertEqual(timestamp, cell.timestamp)
self.assertEqual(receiver_address, cell.receiver_address)
self.assertEqual(sender_addresses, cell.sender_addresses)
+ self.assertEqual(b'', cell.unused)
def test_vpadding_cell(self):
for cell_bytes, payload in VPADDING_CELLS.items():
@@ -262,6 +267,7 @@ class TestCell(unittest.TestCase):
cell = Cell.pop(cell_bytes, 2)[0]
self.assertEqual(challenge, cell.challenge)
self.assertEqual(methods, cell.methods)
+ self.assertEqual(b'', cell.unused)
self.assertRaisesRegexp(ValueError, 'AUTH_CHALLENGE cell should have a payload of 38 bytes, but only had 16', Cell.pop, b'\x00\x00\x82\x00&' + CHALLENGE[:10] + b'\x00\x02\x00\x01\x00\x03', 2)
self.assertRaisesRegexp(ValueError, 'AUTH_CHALLENGE should have 3 methods, but only had 4 bytes for it', Cell.pop, b'\x00\x00\x82\x00&' + CHALLENGE + b'\x00\x03\x00\x01\x00\x03', 2)
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