August 2018 - tor-commits - lists.torproject.org

[stem/master] Add RawRelayCell and temp-fix RelayCell tests (interim)
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 5d86cbde132d7912c411d9134eee6cc05b745d94 Author: Dave Rolek <dmr-x(a)riseup.net> Date: Wed Aug 8 01:14:27 2018 +0000 Add RawRelayCell and temp-fix RelayCell tests (interim) Notably, this along with CANNOT_DIRECTLY_UNPACK for RelayCell (prior change) allows Cell.pop() and Cell.unpack() to be executed directly on received bytes from a connection, and still process encrypted cells correctly into RELAY cells, to be decrypted later. RelayCell tests marked with TODO where temp-fix was applied. RelayCell implementation will gradually be improved/refactored into better supporting subclasses per command. --- stem/client/cell.py | 5 +++++ test/unit/client/cell.py | 34 ++++++++++++++++++++++++---------- 2 files changed, 29 insertions(+), 10 deletions(-) diff --git a/stem/client/cell.py b/stem/client/cell.py index dcebc544..4f7aec79 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -356,6 +356,11 @@ class BaseRelayCell(CircuitCell): return stem.util._hash_attr(self, 'circ_id', 'payload', cache = True) +class RawRelayCell(BaseRelayCell): + NAME = 'RELAY' + VALUE = 3 + + class RelayCell(CircuitCell): """ Command concerning a relay circuit. diff --git a/test/unit/client/cell.py b/test/unit/client/cell.py index b8fe58df..3e091ee5 100644 --- a/test/unit/client/cell.py +++ b/test/unit/client/cell.py @@ -15,6 +15,7 @@ from stem.client.cell import ( Cell, PaddingCell, BaseRelayCell, + RawRelayCell, RelayCell, DestroyCell, CreateFastCell, @@ -93,20 +94,24 @@ AUTH_CHALLENGE_CELLS = { class TestCell(unittest.TestCase): def test_by_name(self): - cls = Cell.by_name('NETINFO') - self.assertEqual('NETINFO', cls.NAME) - self.assertEqual(8, cls.VALUE) - self.assertEqual(True, cls.IS_FIXED_SIZE) + for (expected_class, name, value, is_fixed_size) in ((NetinfoCell, 'NETINFO', 8, True), (RawRelayCell, 'RELAY', 3, True)): + cls = Cell.by_name(name) + self.assertEqual(expected_class, cls) + self.assertEqual(name, cls.NAME) + self.assertEqual(value, cls.VALUE) + self.assertEqual(is_fixed_size, cls.IS_FIXED_SIZE) self.assertRaises(ValueError, Cell.by_name, 'NOPE') self.assertRaises(ValueError, Cell.by_name, 85) self.assertRaises(ValueError, Cell.by_name, None) def test_by_value(self): - cls = Cell.by_value(8) - self.assertEqual('NETINFO', cls.NAME) - self.assertEqual(8, cls.VALUE) - self.assertEqual(True, cls.IS_FIXED_SIZE) + for (expected_class, name, value, is_fixed_size) in ((NetinfoCell, 'NETINFO', 8, True), (RawRelayCell, 'RELAY', 3, True)): + cls = Cell.by_value(value) + self.assertEqual(expected_class, cls) + self.assertEqual(name, cls.NAME) + self.assertEqual(value, cls.VALUE) + self.assertEqual(is_fixed_size, cls.IS_FIXED_SIZE) self.assertRaises(ValueError, Cell.by_value, 'NOPE') self.assertRaises(ValueError, Cell.by_value, 85) @@ -230,7 +235,12 @@ class TestCell(unittest.TestCase): self.assertEqual(cell_bytes, RelayCell(circ_id, command, data, digest, stream_id, unused = unused).pack(link_protocol)) self.assertEqual(cell_bytes, RelayCell(circ_id, command_int, data, digest, stream_id, unused = unused).pack(link_protocol)) - cell = Cell.pop(cell_bytes, link_protocol)[0] + # TODO - temporarily, we hack the interim tests by unpacking info via RawRelayCell + raw_cell = Cell.pop(cell_bytes, link_protocol)[0] + self.assertEqual(circ_id, raw_cell.circ_id) + self.assertEqual(cell_bytes[-FIXED_PAYLOAD_LEN:], raw_cell.payload) + + cell = RelayCell._unpack(raw_cell.payload, raw_cell.circ_id, link_protocol) self.assertEqual(circ_id, cell.circ_id) self.assertEqual(command, cell.command) self.assertEqual(command_int, cell.command_int) @@ -238,7 +248,9 @@ class TestCell(unittest.TestCase): self.assertEqual(digest, cell.digest) self.assertEqual(stream_id, cell.stream_id) self.assertEqual(unused, cell.unused) + self.assertEqual(cell_bytes, cell.pack(link_protocol)) + self.assertEqual(cell_bytes, raw_cell.pack(link_protocol)) digest = hashlib.sha1(b'hi') self.assertEqual(3257622417, RelayCell(5, 'RELAY_BEGIN_DIR', '', digest, 564346860).digest) @@ -258,7 +270,9 @@ class TestCell(unittest.TestCase): ZERO * 498, # data )) - self.assertRaisesWith(ValueError, 'RELAY cell said it had 65535 bytes of data, but only had 498', Cell.pop, mismatched_data_length_bytes, 2) + # TODO - temporarily, we hack the interim tests by unpacking info via RawRelayCell + raw_cell = Cell.pop(mismatched_data_length_bytes, 2)[0] + self.assertRaisesWith(ValueError, 'RELAY cell said it had 65535 bytes of data, but only had 498', RelayCell._unpack, raw_cell.payload, raw_cell.circ_id, 2) def test_destroy_cell(self): for cell_bytes, (circ_id, reason, reason_int, unused, link_protocol) in DESTROY_CELLS.items():

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[stem/master] Standardize some docstring keywords
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit a737624f08aa2a46ff6a91c5459c7644b1e26e3b Author: Dave Rolek <dmr-x(a)riseup.net> Date: Wed Aug 8 19:13:15 2018 +0000 Standardize some docstring keywords s/:parm /:param / s/:raise:/:raises:/ s/:return:/:returns:/ --- stem/client/cell.py | 14 +++++++------- stem/util/log.py | 2 +- stem/util/term.py | 2 +- 3 files changed, 9 insertions(+), 9 deletions(-) diff --git a/stem/client/cell.py b/stem/client/cell.py index f18318da..5ad57788 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -104,9 +104,9 @@ class Cell(object): """ Provides cell attributes by its name. - :parm str name: cell command to fetch + :param str name: cell command to fetch - :raise: **ValueError** if cell type is invalid + :raises: **ValueError** if cell type is invalid """ for _, cls in inspect.getmembers(sys.modules[__name__]): @@ -120,9 +120,9 @@ class Cell(object): """ Provides cell attributes by its value. - :parm int value: cell value to fetch + :param int value: cell value to fetch - :raise: **ValueError** if cell type is invalid + :raises: **ValueError** if cell type is invalid """ for _, cls in inspect.getmembers(sys.modules[__name__]): @@ -202,9 +202,9 @@ class Cell(object): :param bytes payload: cell payload :param int circ_id: circuit id, if a CircuitCell - :return: **bytes** with the encoded payload + :returns: **bytes** with the encoded payload - :raise: **ValueError** if cell type invalid or payload makes cell too large + :raises: **ValueError** if cell type invalid or payload makes cell too large """ if issubclass(cls, CircuitCell): @@ -369,7 +369,7 @@ class RelayCell(CircuitCell): :var stem.client.RelayCommand command: command to be issued :var int command_int: integer value of our command :var bytes data: payload of the cell - :var int recognized: zero if cell is decrypted, non-zero otherwise + :var int recognized: zero if cell is decrypted, otherwise mostly non-zero (can rarely be zero) :var int digest: running digest held with the relay :var int stream_id: specific stream this concerns """ diff --git a/stem/util/log.py b/stem/util/log.py index 81fc88a6..0b2de90a 100644 --- a/stem/util/log.py +++ b/stem/util/log.py @@ -103,7 +103,7 @@ def get_logger(): """ Provides the stem logger. - :return: **logging.Logger** for stem + :returns: **logging.Logger** for stem """ return LOGGER diff --git a/stem/util/term.py b/stem/util/term.py index 3c6fe73a..b4acd61f 100644 --- a/stem/util/term.py +++ b/stem/util/term.py @@ -80,7 +80,7 @@ def encoding(*attrs): :data:`~stem.util.terminal.BgColor`, or :data:`~stem.util.terminal.Attr` to provide an ecoding for - :return: **str** of the ANSI escape sequence, **None** no attributes are + :returns: **str** of the ANSI escape sequence, **None** no attributes are recognized """

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[stem/master] Simplify encryption/decryption implementation in Circuit
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit d355d01a7a4709ffc6941722248c9861e2acd306 Author: Dave Rolek <dmr-x(a)riseup.net> Date: Wed Aug 8 03:06:38 2018 +0000 Simplify encryption/decryption implementation in Circuit This is a proof-of-concept change to show the benefits of migrating finer details into the Cell abstraction. It still arguably violates the Cell abstraction by using RelayCell._unpack(), but that can be addressed in a later change. --- stem/client/__init__.py | 40 ++++++++++++++-------------------------- 1 file changed, 14 insertions(+), 26 deletions(-) diff --git a/stem/client/__init__.py b/stem/client/__init__.py index 24b6de38..71f6d390 100644 --- a/stem/client/__init__.py +++ b/stem/client/__init__.py @@ -34,7 +34,7 @@ import stem.client.cell import stem.socket import stem.util.connection -from stem.client.datatype import ZERO, LinkProtocol, Address, Size, KDF, split +from stem.client.datatype import ZERO, LinkProtocol, Address, KDF __all__ = [ 'cell', @@ -237,45 +237,33 @@ class Circuit(object): orig_digest = self.forward_digest.copy() orig_key = copy.copy(self.forward_key) - # Digests and such are computed using the RELAY cell payload. This - # doesn't include the initial circuit id and cell type fields. - # Circuit ids vary in length depending on the protocol version. - - header_size = self.relay.link_protocol.circ_id_size.size + 1 - try: + # Digests and such are computed using the RELAY cell payload. cell = stem.client.cell.RelayCell(self.id, command, data, 0, stream_id) - payload_without_digest = cell.pack(self.relay.link_protocol)[header_size:] + payload_without_digest = cell.pack(self.relay.link_protocol)[-stem.client.cell.FIXED_PAYLOAD_LEN:] self.forward_digest.update(payload_without_digest) cell = stem.client.cell.RelayCell(self.id, command, data, self.forward_digest, stream_id) - header, payload = split(cell.pack(self.relay.link_protocol), header_size) - encrypted_payload = header + self.forward_key.update(payload) + payload_with_digest = cell.pack(self.relay.link_protocol)[-stem.client.cell.FIXED_PAYLOAD_LEN:] + encrypted_payload = self.forward_key.update(payload_with_digest) + encrypted_cell = stem.client.cell.RawRelayCell(self.id, encrypted_payload) reply_cells = [] - self.relay._orport.send(encrypted_payload) + self.relay._orport.send(encrypted_cell.pack(self.relay.link_protocol)) reply = self.relay._orport.recv() - # Check that we got the correct number of bytes for a series of RELAY cells - - relay_cell_size = header_size + stem.client.cell.FIXED_PAYLOAD_LEN relay_cell_cmd = stem.client.cell.RelayCell.VALUE - if len(reply) % relay_cell_size != 0: - raise stem.ProtocolError('Circuit response should be a series of RELAY cells, but received an unexpected size for a response: %i' % len(reply)) - while reply: - circ_id, reply = self.relay.link_protocol.circ_id_size.pop(reply) - command, reply = Size.CHAR.pop(reply) - payload, reply = split(reply, stem.client.cell.FIXED_PAYLOAD_LEN) + raw_cell, reply = stem.client.cell.Cell.pop(reply, self.relay.link_protocol) - if command != relay_cell_cmd: - raise stem.ProtocolError('RELAY cell responses should be %i but was %i' % (relay_cell_cmd, command)) - elif circ_id != self.id: - raise stem.ProtocolError('Response should be for circuit id %i, not %i' % (self.id, circ_id)) + if raw_cell.VALUE != relay_cell_cmd: + raise stem.ProtocolError('RELAY cell responses should be %i but was %i' % (relay_cell_cmd, raw_cell.VALUE)) + elif raw_cell.circ_id != self.id: + raise stem.ProtocolError('Response should be for circuit id %i, not %i' % (self.id, raw_cell.circ_id)) - decrypted = self.backward_key.update(payload) - reply_cells.append(stem.client.cell.RelayCell._unpack(decrypted, self.id, self.relay.link_protocol)) + decrypted_payload = self.backward_key.update(raw_cell.payload) + reply_cells.append(stem.client.cell.RelayCell._unpack(decrypted_payload, self.id, self.relay.link_protocol)) return reply_cells except:

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[stem/master] Document RawRelayCell in the module overview
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 98398f6dbce3bca2f146d40abf3894ea2755e054 Author: Dave Rolek <dmr-x(a)riseup.net> Date: Thu Aug 9 19:18:13 2018 +0000 Document RawRelayCell in the module overview The line is long, so this change also extends the vertically aligned table format for other Cell classes, in a forward-looking manner. Arguably this could've been part of the previous change, but it made sense to break it out for readability purposes. --- stem/client/cell.py | 39 ++++++++++++++++++++------------------- 1 file changed, 20 insertions(+), 19 deletions(-) diff --git a/stem/client/cell.py b/stem/client/cell.py index 4f7aec79..f18318da 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -12,26 +12,27 @@ Messages communicated over a Tor relay's ORPort. Cell - Base class for ORPort messages. |- CircuitCell - Circuit management. - | |- CreateCell - Create a circuit. (section 5.1) - | |- CreatedCell - Acknowledge create. (section 5.1) - | |- BaseRelayCell - End-to-end data; abstract. (section 6.1) - | |- RelayCell - End-to-end data. (section 6.1) - | |- DestroyCell - Stop using a circuit. (section 5.4) - | |- CreateFastCell - Create a circuit, no PK. (section 5.1) - | |- CreatedFastCell - Circuit created, no PK. (section 5.1) - | |- RelayEarlyCell - End-to-end data; limited. (section 5.6) - | |- Create2Cell - Extended CREATE cell. (section 5.1) - | +- Created2Cell - Extended CREATED cell. (section 5.1) + | |- CreateCell - Create a circuit. (section 5.1) + | |- CreatedCell - Acknowledge create. (section 5.1) + | |- BaseRelayCell - End-to-end data; abstract. (section 6.1) + | | +- RawRelayCell - End-to-end data. Payload not unpacked. (section 5.5.2.1, 5.5.3) + | |- RelayCell - End-to-end data. (section 6.1) + | |- DestroyCell - Stop using a circuit. (section 5.4) + | |- CreateFastCell - Create a circuit, no PK. (section 5.1) + | |- CreatedFastCell - Circuit created, no PK. (section 5.1) + | |- RelayEarlyCell - End-to-end data; limited. (section 5.6) + | |- Create2Cell - Extended CREATE cell. (section 5.1) + | +- Created2Cell - Extended CREATED cell. (section 5.1) | - |- PaddingCell - Padding negotiation. (section 7.2) - |- VersionsCell - Negotiate proto version. (section 4) - |- NetinfoCell - Time and address info. (section 4.5) - |- PaddingNegotiateCell - Padding negotiation. (section 7.2) - |- VPaddingCell - Variable-length padding. (section 7.2) - |- CertsCell - Relay certificates. (section 4.2) - |- AuthChallengeCell - Challenge value. (section 4.3) - |- AuthenticateCell - Client authentication. (section 4.5) - |- AuthorizeCell - Client authorization. (not yet used) + |- PaddingCell - Padding negotiation. (section 7.2) + |- VersionsCell - Negotiate proto version. (section 4) + |- NetinfoCell - Time and address info. (section 4.5) + |- PaddingNegotiateCell - Padding negotiation. (section 7.2) + |- VPaddingCell - Variable-length padding. (section 7.2) + |- CertsCell - Relay certificates. (section 4.2) + |- AuthChallengeCell - Challenge value. (section 4.3) + |- AuthenticateCell - Client authentication. (section 4.5) + |- AuthorizeCell - Client authorization. (not yet used) | |- pack - encodes cell into bytes |- unpack - decodes series of cells

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[stem/master] Refactor payload parsing (unpacking) into separate method
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 0d18570de51486ffa63ad0fe2f8b71be44b34f55 Author: Dave Rolek <dmr-x(a)riseup.net> Date: Wed Aug 8 17:31:29 2018 +0000 Refactor payload parsing (unpacking) into separate method Eventually, having this separated out will help during decryption of cells in multi-hop circuits - each layer of decryption must attempt to interpret the payload in order to ascertain whether it has been fully decrypted. --- stem/client/cell.py | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/stem/client/cell.py b/stem/client/cell.py index a7b57326..9194c29c 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -436,6 +436,23 @@ class RelayCell(CircuitCell): @classmethod def _unpack(cls, content, circ_id, link_protocol): + command, recognized, stream_id, digest, data_len, data, unused = RelayCell._unpack_payload(content) + + if len(data) != data_len: + raise ValueError('%s cell said it had %i bytes of data, but only had %i' % (cls.NAME, data_len, len(data))) + + return RelayCell(circ_id, command, data, digest, stream_id, recognized, unused) + + @staticmethod + def _unpack_payload(content): + """ + Directly interpret the payload without any validation. + + :param bytes content: cell payload + + :returns: (command, recognized, stream_id, digest, data_len, data, unused) tuple + """ + command, content = Size.CHAR.pop(content) recognized, content = Size.SHORT.pop(content) # 'recognized' field stream_id, content = Size.SHORT.pop(content) @@ -443,10 +460,7 @@ class RelayCell(CircuitCell): data_len, content = Size.SHORT.pop(content) data, unused = split(content, data_len) - if len(data) != data_len: - raise ValueError('%s cell said it had %i bytes of data, but only had %i' % (cls.NAME, data_len, len(data))) - - return RelayCell(circ_id, command, data, digest, stream_id, recognized, unused) + return command, recognized, stream_id, digest, data_len, data, unused def __hash__(self): return stem.util._hash_attr(self, 'command_int', 'stream_id', 'digest', 'data', cache = True)

1 0

[stem/master] Refactor digest coercion into separate method
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 853d7336580dae6f080b61a3991fe0a73e498b7f Author: Dave Rolek <dmr-x(a)riseup.net> Date: Fri Aug 10 21:40:59 2018 +0000 Refactor digest coercion into separate method This allows the logic to be reused. It may ultimately be better represented as a @property, but for now this should do fine. --- stem/client/cell.py | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/stem/client/cell.py b/stem/client/cell.py index 5ad57788..a7b57326 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -380,6 +380,32 @@ class RelayCell(CircuitCell): CANNOT_DIRECTLY_UNPACK = True def __init__(self, circ_id, command, data, digest = 0, stream_id = 0, recognized = 0, unused = b''): + digest = RelayCell._coerce_digest(digest) + + super(RelayCell, self).__init__(circ_id, unused) + self.command, self.command_int = RelayCommand.get(command) + self.recognized = recognized + self.stream_id = stream_id + self.digest = digest + self.data = str_tools._to_bytes(data) + + if digest == 0: + if not stream_id and self.command in STREAM_ID_REQUIRED: + raise ValueError('%s relay cells require a stream id' % self.command) + elif stream_id and self.command in STREAM_ID_DISALLOWED: + raise ValueError('%s relay cells concern the circuit itself and cannot have a stream id' % self.command) + + @staticmethod + def _coerce_digest(digest): + """ + Coerce any of HASH, str, int into the proper digest type for packing + + :param HASH,str,int digest: digest to be coerced + :returns: digest in type appropriate for packing + + :raises: **ValueError** if input digest type is unsupported + """ + 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 @@ -395,18 +421,7 @@ 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, unused) - self.command, self.command_int = RelayCommand.get(command) - self.recognized = recognized - self.stream_id = stream_id - self.digest = digest - self.data = str_tools._to_bytes(data) - - if digest == 0: - if not stream_id and self.command in STREAM_ID_REQUIRED: - raise ValueError('%s relay cells require a stream id' % self.command) - elif stream_id and self.command in STREAM_ID_DISALLOWED: - raise ValueError('%s relay cells concern the circuit itself and cannot have a stream id' % self.command) + return digest def pack(self, link_protocol): payload = bytearray()

1 0

[stem/master] Refactor 'unused' and padding packing into the RELAY cell payload
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 09c171d60c2b1414aae791d2347b6385caca03de Author: Dave Rolek <dmr-x(a)riseup.net> Date: Thu Aug 9 20:28:15 2018 +0000 Refactor 'unused' and padding packing into the RELAY cell payload This is more appropriate since the spec allows for (and recommends!) different behavior for these bytes than other padding bytes. However, presently the handling is identical. It is also important that the _pack_payload() method be able to produce a full-size payload, for simplifying encryption. --- stem/client/cell.py | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/stem/client/cell.py b/stem/client/cell.py index 7c09d0e0..42b95571 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -424,9 +424,9 @@ class RelayCell(CircuitCell): return digest def pack(self, link_protocol): - payload = RelayCell._pack_payload(self.command_int, self.recognized, self.stream_id, self.digest, len(self.data), self.data) + payload = RelayCell._pack_payload(self.command_int, self.recognized, self.stream_id, self.digest, len(self.data), self.data, self.unused) - return RelayCell._pack(link_protocol, payload, self.unused, self.circ_id) + return RelayCell._pack(link_protocol, payload, unused = b'', circ_id = self.circ_id) @classmethod def _unpack(cls, content, circ_id, link_protocol): @@ -457,7 +457,7 @@ class RelayCell(CircuitCell): return command, recognized, stream_id, digest, data_len, data, unused @staticmethod - def _pack_payload(command_int, recognized, stream_id, digest, data_len, data): + def _pack_payload(command_int, recognized, stream_id, digest, data_len, data, unused = b'', pad_remainder = True): """ Directly pack the payload without any validation beyond Size constraints. @@ -467,6 +467,8 @@ class RelayCell(CircuitCell): :param HASH,str,int digest: running digest held with the relay :param int data_len: length of body data :param bytes data: body data of the cell + :param bytes unused: padding bytes to include after data + :param bool pad_remaining: pads up to payload size if **True** :returns: **bytes** with the packed payload """ @@ -478,6 +480,16 @@ class RelayCell(CircuitCell): payload += Size.LONG.pack(RelayCell._coerce_digest(digest)) payload += Size.SHORT.pack(data_len) payload += data + payload += unused + + if len(payload) > FIXED_PAYLOAD_LEN: + raise ValueError('Payload is too large (%i bytes), must not be more than %i.' % (len(payload), FIXED_PAYLOAD_LEN)) + + if pad_remainder: + # right now, it is acceptable to pad the remaining portion with ZEROs instead of random + # this is done due to threat model and simplifying some implementation + # however: in the future (TODO), this may become against the spec; see prop 289 + payload += ZERO * (FIXED_PAYLOAD_LEN - len(payload)) return bytes(payload)

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[stem/master] Refactor payload packing into separate method
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 71c8464c24e4b2af350cfdd9217c0712c538447a Author: Dave Rolek <dmr-x(a)riseup.net> Date: Wed Aug 8 19:04:52 2018 +0000 Refactor payload packing into separate method It's important to decouple packing the payload from packing the whole cell. This is probably not the final form this method will take, but in the interim, it should help reduce the magnitude of violating the Cell abstraction layer, for any payload encryption/decryption. --- stem/client/cell.py | 35 +++++++++++++++++++++++++++-------- 1 file changed, 27 insertions(+), 8 deletions(-) diff --git a/stem/client/cell.py b/stem/client/cell.py index 9194c29c..7c09d0e0 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -424,15 +424,9 @@ class RelayCell(CircuitCell): return digest def pack(self, link_protocol): - payload = bytearray() - payload += Size.CHAR.pack(self.command_int) - payload += Size.SHORT.pack(self.recognized) - payload += Size.SHORT.pack(self.stream_id) - payload += Size.LONG.pack(self.digest) - payload += Size.SHORT.pack(len(self.data)) - payload += self.data + payload = RelayCell._pack_payload(self.command_int, self.recognized, self.stream_id, self.digest, len(self.data), self.data) - return RelayCell._pack(link_protocol, bytes(payload), self.unused, self.circ_id) + return RelayCell._pack(link_protocol, payload, self.unused, self.circ_id) @classmethod def _unpack(cls, content, circ_id, link_protocol): @@ -462,6 +456,31 @@ class RelayCell(CircuitCell): return command, recognized, stream_id, digest, data_len, data, unused + @staticmethod + def _pack_payload(command_int, recognized, stream_id, digest, data_len, data): + """ + Directly pack the payload without any validation beyond Size constraints. + + :param int command_int: integer value of our command + :param int recognized: zero if cell is decrypted, otherwise mostly non-zero (can rarely be zero) + :param int stream_id: specific stream this concerns + :param HASH,str,int digest: running digest held with the relay + :param int data_len: length of body data + :param bytes data: body data of the cell + + :returns: **bytes** with the packed payload + """ + + payload = bytearray() + payload += Size.CHAR.pack(command_int) + payload += Size.SHORT.pack(recognized) + payload += Size.SHORT.pack(stream_id) + payload += Size.LONG.pack(RelayCell._coerce_digest(digest)) + payload += Size.SHORT.pack(data_len) + payload += data + + return bytes(payload) + def __hash__(self): return stem.util._hash_attr(self, 'command_int', 'stream_id', 'digest', 'data', cache = True)

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[stem/master] Fix docstring 'import path' for RelayCommand
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 36f341f7c882d846b1305beb1a29906a2b97d590 Author: Dave Rolek <dmr-x(a)riseup.net> Date: Sat Aug 11 19:18:09 2018 +0000 Fix docstring 'import path' for RelayCommand --- stem/client/__init__.py | 2 +- stem/client/cell.py | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/stem/client/__init__.py b/stem/client/__init__.py index 83c20365..b0500c4a 100644 --- a/stem/client/__init__.py +++ b/stem/client/__init__.py @@ -227,7 +227,7 @@ class Circuit(object): """ Sends a message over the circuit. - :param stem.client.RelayCommand command: command to be issued + :param stem.client.datatype.RelayCommand command: command to be issued :param bytes data: message payload :param int stream_id: specific stream this concerns diff --git a/stem/client/cell.py b/stem/client/cell.py index 42b95571..381a7387 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -366,7 +366,7 @@ class RelayCell(CircuitCell): """ Command concerning a relay circuit. - :var stem.client.RelayCommand command: command to be issued + :var stem.client.datatype.RelayCommand command: command to be issued :var int command_int: integer value of our command :var bytes data: payload of the cell :var int recognized: zero if cell is decrypted, otherwise mostly non-zero (can rarely be zero)

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[stem/master] Further simplify digest calculation for encryption
by atagar＠torproject.org 26 Aug '18

26 Aug '18

commit 2a76a0acfcf6aa9def2d6585ec8e53eae19b4c3c Author: Dave Rolek <dmr-x(a)riseup.net> Date: Thu Aug 9 21:12:27 2018 +0000 Further simplify digest calculation for encryption This is a continuation of proof-of-concept changes. Again, this is not the final form that encryption will take on. --- stem/client/__init__.py | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/stem/client/__init__.py b/stem/client/__init__.py index 71f6d390..83c20365 100644 --- a/stem/client/__init__.py +++ b/stem/client/__init__.py @@ -32,6 +32,7 @@ import threading import stem import stem.client.cell import stem.socket +from stem.util import str_tools import stem.util.connection from stem.client.datatype import ZERO, LinkProtocol, Address, KDF @@ -239,12 +240,15 @@ class Circuit(object): try: # Digests and such are computed using the RELAY cell payload. - cell = stem.client.cell.RelayCell(self.id, command, data, 0, stream_id) - payload_without_digest = cell.pack(self.relay.link_protocol)[-stem.client.cell.FIXED_PAYLOAD_LEN:] + + _, command_int = stem.client.datatype.RelayCommand.get(command) + # coerce to bytes, just in case + data = str_tools._to_bytes(data) + + payload_without_digest = stem.client.cell.RelayCell._pack_payload(command_int, 0, stream_id, 0, len(data), data) self.forward_digest.update(payload_without_digest) + payload_with_digest = stem.client.cell.RelayCell._pack_payload(command_int, 0, stream_id, self.forward_digest, len(data), data) - cell = stem.client.cell.RelayCell(self.id, command, data, self.forward_digest, stream_id) - payload_with_digest = cell.pack(self.relay.link_protocol)[-stem.client.cell.FIXED_PAYLOAD_LEN:] encrypted_payload = self.forward_key.update(payload_with_digest) encrypted_cell = stem.client.cell.RawRelayCell(self.id, encrypted_payload)

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