commit b7ae57c4bcface5314700b38781ae6fbac65ad25 Author: Damian Johnson atagar@torproject.org Date: Sun Jan 14 11:19:25 2018 -0800

Use BytesIO for cell packing

Not a terribly big whoop, but probably a tad more performant. --- stem/client/cell.py | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/stem/client/cell.py b/stem/client/cell.py index 73c1c8f2..4fe7952e 100644 --- a/stem/client/cell.py +++ b/stem/client/cell.py @@ -135,6 +135,13 @@ class Cell(object): def _pack(cls, link_version, payload, circ_id = 0): """ Provides bytes that can be used on the wire for these cell attributes. + Format of a properly packed cell depends on if it's fixed or variable + sized... + + :: + + Fixed: [ CircuitID ][ Command ][ Payload ][ Padding ] + Variable: [ CircuitID ][ Command ][ Size ][ Payload ]

:param str name: cell command :param int link_version: link protocol version @@ -146,22 +153,24 @@ class Cell(object): :raise: **ValueError** if cell type invalid or payload is too large """

- packed_circ_id = Size.LONG.pack(circ_id) if link_version > 3 else Size.SHORT.pack(circ_id) - packed_command = Size.CHAR.pack(cls.VALUE) - packed_size = b'' if cls.IS_FIXED_SIZE else Size.SHORT.pack(len(payload)) - cell = b''.join((packed_circ_id, packed_command, packed_size, payload)) + cell = io.BytesIO() + cell.write(Size.LONG.pack(circ_id) if link_version > 3 else Size.SHORT.pack(circ_id)) + cell.write(Size.CHAR.pack(cls.VALUE)) + cell.write(b'' if cls.IS_FIXED_SIZE else Size.SHORT.pack(len(payload))) + cell.write(payload)

# pad fixed sized cells to the required length

if cls.IS_FIXED_SIZE: + cell_size = cell.seek(0, io.SEEK_END) fixed_cell_len = 514 if link_version > 3 else 512

- if len(cell) > fixed_cell_len: - raise ValueError('Payload of %s is too large (%i bytes), must be less than %i' % (cls.NAME, len(cell), fixed_cell_len)) + if cell_size > fixed_cell_len: + raise ValueError('Payload of %s is too large (%i bytes), must be less than %i' % (cls.NAME, cell_size, fixed_cell_len))

- cell += ZERO * (fixed_cell_len - len(cell)) + cell.write(ZERO * (fixed_cell_len - cell_size))

- return cell + return cell.getvalue()

@classmethod def _unpack(cls, content, circ_id, link_version):