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mirror of https://github.com/trezor/trezor-firmware.git synced 2024-12-24 07:18:09 +00:00
trezor-firmware/trezorlib/protocol_v2.py

144 lines
5.1 KiB
Python

# This file is part of the TREZOR project.
#
# Copyright (C) 2012-2016 Marek Palatinus <slush@satoshilabs.com>
# Copyright (C) 2012-2016 Pavol Rusnak <stick@satoshilabs.com>
#
# This library is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this library. If not, see <http://www.gnu.org/licenses/>.
from __future__ import absolute_import
from io import BytesIO
import logging
import struct
from typing import Tuple
from . import mapping
from . import protobuf
from .transport import Transport
REPLEN = 64
LOG = logging.getLogger(__name__)
class ProtocolV2:
def __init__(self) -> None:
self.session = None
def session_begin(self, transport: Transport) -> None:
chunk = struct.pack('>B', 0x03)
chunk = chunk.ljust(REPLEN, b'\x00')
transport.write_chunk(chunk)
resp = transport.read_chunk()
self.session = self.parse_session_open(resp)
LOG.debug("[session {}] session started".format(self.session))
def session_end(self, transport: Transport) -> None:
if not self.session:
return
chunk = struct.pack('>BL', 0x04, self.session)
chunk = chunk.ljust(REPLEN, b'\x00')
transport.write_chunk(chunk)
resp = transport.read_chunk()
(magic, ) = struct.unpack('>B', resp[:1])
if magic != 0x04:
raise RuntimeError('Expected session close')
LOG.debug("[session {}] session ended".format(self.session))
self.session = None
def write(self, transport: Transport, msg: protobuf.MessageType) -> None:
if not self.session:
raise RuntimeError('Missing session for v2 protocol')
LOG.debug("[session {}] sending message: {}".format(self.session, msg.__class__.__name__),
extra={'protobuf': msg})
# Serialize whole message
data = BytesIO()
protobuf.dump_message(data, msg)
data = data.getvalue()
dataheader = struct.pack('>LL', mapping.get_type(msg), len(data))
data = dataheader + data
seq = -1
# Write it out
while data:
if seq < 0:
repheader = struct.pack('>BL', 0x01, self.session)
else:
repheader = struct.pack('>BLL', 0x02, self.session, seq)
datalen = REPLEN - len(repheader)
chunk = repheader + data[:datalen]
chunk = chunk.ljust(REPLEN, b'\x00')
transport.write_chunk(chunk)
data = data[datalen:]
seq += 1
def read(self, transport: Transport) -> protobuf.MessageType:
if not self.session:
raise RuntimeError('Missing session for v2 protocol')
# Read header with first part of message data
chunk = transport.read_chunk()
msg_type, datalen, data = self.parse_first(chunk)
# Read the rest of the message
while len(data) < datalen:
chunk = transport.read_chunk()
next_data = self.parse_next(chunk)
data.extend(next_data)
# Strip padding
data = BytesIO(data[:datalen])
# Parse to protobuf
msg = protobuf.load_message(data, mapping.get_class(msg_type))
LOG.debug("[session {}] received message: {}".format(self.session, msg.__class__.__name__),
extra={'protobuf': msg})
return msg
def parse_first(self, chunk: bytes) -> Tuple[int, int, bytes]:
try:
headerlen = struct.calcsize('>BLLL')
magic, session, msg_type, datalen = struct.unpack('>BLLL', chunk[:headerlen])
except:
raise RuntimeError('Cannot parse header')
if magic != 0x01:
raise RuntimeError('Unexpected magic character')
if session != self.session:
raise RuntimeError('Session id mismatch')
return msg_type, datalen, chunk[headerlen:]
def parse_next(self, chunk: bytes) -> bytes:
try:
headerlen = struct.calcsize('>BLL')
magic, session, sequence = struct.unpack('>BLL', chunk[:headerlen])
except:
raise RuntimeError('Cannot parse header')
if magic != 0x02:
raise RuntimeError('Unexpected magic characters')
if session != self.session:
raise RuntimeError('Session id mismatch')
return chunk[headerlen:]
def parse_session_open(self, chunk: bytes) -> int:
try:
headerlen = struct.calcsize('>BL')
magic, session = struct.unpack('>BL', chunk[:headerlen])
except:
raise RuntimeError('Cannot parse header')
if magic != 0x03:
raise RuntimeError('Unexpected magic character')
return session