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trezor-firmware/trezorlib/protocol_v1.py
2018-08-13 18:22:19 +02:00

92 lines
2.9 KiB
Python

# This file is part of the Trezor project.
#
# Copyright (C) 2012-2018 SatoshiLabs and contributors
#
# This library is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3
# as published by the Free Software Foundation.
#
# 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 License along with this library.
# If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
import logging
import struct
from io import BytesIO
from typing import Tuple
from . import mapping, protobuf
from .transport import Transport
REPLEN = 64
LOG = logging.getLogger(__name__)
class ProtocolV1:
def session_begin(self, transport: Transport) -> None:
pass
def session_end(self, transport: Transport) -> None:
pass
def write(self, transport: Transport, msg: protobuf.MessageType) -> None:
LOG.debug(
"sending message: {}".format(msg.__class__.__name__),
extra={"protobuf": msg},
)
data = BytesIO()
protobuf.dump_message(data, msg)
ser = data.getvalue()
header = struct.pack(">HL", mapping.get_type(msg), len(ser))
data = bytearray(b"##" + header + ser)
while data:
# Report ID, data padded to 63 bytes
chunk = b"?" + data[: REPLEN - 1]
chunk = chunk.ljust(REPLEN, b"\x00")
transport.write_chunk(chunk)
data = data[63:]
def read(self, transport: Transport) -> protobuf.MessageType:
# 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()
data.extend(self.parse_next(chunk))
# Strip padding
data = BytesIO(data[:datalen])
# Parse to protobuf
msg = protobuf.load_message(data, mapping.get_class(msg_type))
LOG.debug(
"received message: {}".format(msg.__class__.__name__),
extra={"protobuf": msg},
)
return msg
def parse_first(self, chunk: bytes) -> Tuple[int, int, bytes]:
if chunk[:3] != b"?##":
raise RuntimeError("Unexpected magic characters")
try:
headerlen = struct.calcsize(">HL")
msg_type, datalen = struct.unpack(">HL", chunk[3 : 3 + headerlen])
except Exception:
raise RuntimeError("Cannot parse header")
data = chunk[3 + headerlen :]
return msg_type, datalen, data
def parse_next(self, chunk: bytes) -> bytes:
if chunk[:1] != b"?":
raise RuntimeError("Unexpected magic characters")
return chunk[1:]