mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-11-24 08:28:12 +00:00
140 lines
5.0 KiB
Python
140 lines
5.0 KiB
Python
# This file is part of the Trezor project.
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#
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# Copyright (C) 2012-2018 SatoshiLabs and contributors
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#
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# This library is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License version 3
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# as published by the Free Software Foundation.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the License along with this library.
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# If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
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from io import BytesIO
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import logging
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import struct
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from typing import Tuple
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from . import mapping
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from . import protobuf
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from .transport import Transport
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REPLEN = 64
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LOG = logging.getLogger(__name__)
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class ProtocolV2:
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def __init__(self) -> None:
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self.session = None
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def session_begin(self, transport: Transport) -> None:
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chunk = struct.pack('>B', 0x03)
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chunk = chunk.ljust(REPLEN, b'\x00')
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transport.write_chunk(chunk)
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resp = transport.read_chunk()
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self.session = self.parse_session_open(resp)
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LOG.debug("[session {}] session started".format(self.session))
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def session_end(self, transport: Transport) -> None:
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if not self.session:
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return
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chunk = struct.pack('>BL', 0x04, self.session)
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chunk = chunk.ljust(REPLEN, b'\x00')
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transport.write_chunk(chunk)
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resp = transport.read_chunk()
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(magic, ) = struct.unpack('>B', resp[:1])
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if magic != 0x04:
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raise RuntimeError('Expected session close')
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LOG.debug("[session {}] session ended".format(self.session))
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self.session = None
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def write(self, transport: Transport, msg: protobuf.MessageType) -> None:
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if not self.session:
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raise RuntimeError('Missing session for v2 protocol')
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LOG.debug("[session {}] sending message: {}".format(self.session, msg.__class__.__name__),
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extra={'protobuf': msg})
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# Serialize whole message
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data = BytesIO()
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protobuf.dump_message(data, msg)
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data = data.getvalue()
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dataheader = struct.pack('>LL', mapping.get_type(msg), len(data))
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data = dataheader + data
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seq = -1
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# Write it out
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while data:
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if seq < 0:
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repheader = struct.pack('>BL', 0x01, self.session)
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else:
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repheader = struct.pack('>BLL', 0x02, self.session, seq)
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datalen = REPLEN - len(repheader)
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chunk = repheader + data[:datalen]
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chunk = chunk.ljust(REPLEN, b'\x00')
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transport.write_chunk(chunk)
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data = data[datalen:]
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seq += 1
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def read(self, transport: Transport) -> protobuf.MessageType:
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if not self.session:
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raise RuntimeError('Missing session for v2 protocol')
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# Read header with first part of message data
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chunk = transport.read_chunk()
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msg_type, datalen, data = self.parse_first(chunk)
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# Read the rest of the message
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while len(data) < datalen:
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chunk = transport.read_chunk()
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next_data = self.parse_next(chunk)
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data.extend(next_data)
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# Strip padding
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data = BytesIO(data[:datalen])
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# Parse to protobuf
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msg = protobuf.load_message(data, mapping.get_class(msg_type))
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LOG.debug("[session {}] received message: {}".format(self.session, msg.__class__.__name__),
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extra={'protobuf': msg})
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return msg
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def parse_first(self, chunk: bytes) -> Tuple[int, int, bytes]:
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try:
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headerlen = struct.calcsize('>BLLL')
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magic, session, msg_type, datalen = struct.unpack('>BLLL', chunk[:headerlen])
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except Exception:
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raise RuntimeError('Cannot parse header')
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if magic != 0x01:
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raise RuntimeError('Unexpected magic character')
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if session != self.session:
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raise RuntimeError('Session id mismatch')
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return msg_type, datalen, chunk[headerlen:]
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def parse_next(self, chunk: bytes) -> bytes:
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try:
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headerlen = struct.calcsize('>BLL')
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magic, session, sequence = struct.unpack('>BLL', chunk[:headerlen])
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except Exception:
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raise RuntimeError('Cannot parse header')
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if magic != 0x02:
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raise RuntimeError('Unexpected magic characters')
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if session != self.session:
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raise RuntimeError('Session id mismatch')
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return chunk[headerlen:]
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def parse_session_open(self, chunk: bytes) -> int:
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try:
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headerlen = struct.calcsize('>BL')
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magic, session = struct.unpack('>BL', chunk[:headerlen])
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except Exception:
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raise RuntimeError('Cannot parse header')
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if magic != 0x03:
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raise RuntimeError('Unexpected magic character')
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return session
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