def get_cell_cmd(cell_bytes: bytes, link_version: int):
"""
Get the command of a cell which is represented in bytes
:param cell_bytes: the bytes of the cell
:param link_version: the link version of the cell
:return: the cells command
"""
cmd = struct.unpack(PACK_FMT[public_constants.CMD_LEN], cell_bytes[public_constants.CIRCID_LEN(
link_version):public_constants.CIRCID_LEN(link_version) + public_constants.CMD_LEN])[0]
return cmd
def get_relay_cmd(cell_bytes: bytes, link_version: int):
"""
Get the command of the relay cell which is in bytes
:param cell_bytes: the cell bytes
:param link_version: the link version of the cell
:return: the relay command
"""
cmd = struct.unpack(PACK_FMT[public_constants.CMD_LEN], cell_bytes[public_constants.CIRCID_LEN(
link_version) + public_constants.CMD_LEN:public_constants.CIRCID_LEN(
link_version) + public_constants.CMD_LEN * 2])[0]
return cmd
def set_fmt_string(self):
"""
Sets the string format of the cell based on the link version.
:return: None
"""
if public_constants.CIRCID_LEN(self.link_version) == 2:
self.fmt_string = '!HB'
else:
self.fmt_string = '!LB'
def buffer_ok(self, buffer: bytes):
"""
Checks if the buffer starts with the correct circuit ID
:param buffer: buffer of bytes from the read
:return:True if recognized, False otherwise
"""
return int.from_bytes(
buffer[:public_constants.CIRCID_LEN(self.link_version)],
'big') == self.circID
def set_fmt_string(self):
if public_constants.CIRCID_LEN(self.link_version) == 2:
self.fmt_string = '!HBH'
else:
self.fmt_string = '!LBH'