trezor-firmware/trezorlib/transport/hid.py

# 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 sys
import time
from typing import Any, Dict, Iterable

from . import DEV_TREZOR1, UDEV_RULES_STR, TransportException
from .protocol import ProtocolBasedTransport, ProtocolV1

LOG = logging.getLogger(__name__)

try:
    import hid
except Exception as e:
    LOG.info("HID transport is disabled: {}".format(e))
    hid = None


HidDevice = Dict[str, Any]
HidDeviceHandle = Any


class HidHandle:
    def __init__(
        self, path: bytes, serial: str, probe_hid_version: bool = False
    ) -> None:
        self.path = path
        self.serial = serial
        self.handle = None  # type: HidDeviceHandle
        self.hid_version = None if probe_hid_version else 2

    def open(self) -> None:
        self.handle = hid.device()
        try:
            self.handle.open_path(self.path)
        except (IOError, OSError) as e:
            if sys.platform.startswith("linux"):
                e.args = e.args + (UDEV_RULES_STR,)
            raise e

        # On some platforms, HID path stays the same over device reconnects.
        # That means that someone could unplug a Trezor, plug a different one
        # and we wouldn't even know.
        # So we check that the serial matches what we expect.
        serial = self.handle.get_serial_number_string()
        if serial != self.serial:
            self.handle.close()
            self.handle = None
            raise TransportException(
                "Unexpected device {} on path {}".format(serial, self.path.decode())
            )

        self.handle.set_nonblocking(True)

        if self.hid_version is None:
            self.hid_version = self.probe_hid_version()

    def close(self) -> None:
        if self.handle is not None:
            # reload serial, because device.wipe() can reset it
            self.serial = self.handle.get_serial_number_string()
            self.handle.close()
        self.handle = None

    def write_chunk(self, chunk: bytes) -> None:
        if len(chunk) != 64:
            raise TransportException("Unexpected chunk size: %d" % len(chunk))

        if self.hid_version == 2:
            self.handle.write(b"\0" + bytearray(chunk))
        else:
            self.handle.write(chunk)

    def read_chunk(self) -> bytes:
        while True:
            chunk = self.handle.read(64)
            if chunk:
                break
            else:
                time.sleep(0.001)
        if len(chunk) != 64:
            raise TransportException("Unexpected chunk size: %d" % len(chunk))
        return bytes(chunk)

    def probe_hid_version(self) -> int:
        n = self.handle.write([0, 63] + [0xFF] * 63)
        if n == 65:
            return 2
        n = self.handle.write([63] + [0xFF] * 63)
        if n == 64:
            return 1
        raise TransportException("Unknown HID version")


class HidTransport(ProtocolBasedTransport):
    """
    HidTransport implements transport over USB HID interface.
    """

    PATH_PREFIX = "hid"
    ENABLED = hid is not None

    def __init__(self, device: HidDevice) -> None:
        self.device = device
        self.handle = HidHandle(device["path"], device["serial_number"])

        protocol = ProtocolV1(self.handle)
        super().__init__(protocol=protocol)

    def get_path(self) -> str:
        return "%s:%s" % (self.PATH_PREFIX, self.device["path"].decode())

    @classmethod
    def enumerate(cls, debug: bool = False) -> Iterable["HidTransport"]:
        devices = []
        for dev in hid.enumerate(0, 0):
            usb_id = (dev["vendor_id"], dev["product_id"])
            if usb_id != DEV_TREZOR1:
                continue
            if debug:
                if not is_debuglink(dev):
                    continue
            else:
                if not is_wirelink(dev):
                    continue
            devices.append(HidTransport(dev))
        return devices

    def find_debug(self) -> "HidTransport":
        if self.protocol.VERSION >= 2:
            # use the same device
            return self
        else:
            # For v1 protocol, find debug USB interface for the same serial number
            for debug in HidTransport.enumerate(debug=True):
                if debug.device["serial_number"] == self.device["serial_number"]:
                    return debug
            raise TransportException("Debug HID device not found")


def is_wirelink(dev: HidDevice) -> bool:
    return dev["usage_page"] == 0xFF00 or dev["interface_number"] == 0


def is_debuglink(dev: HidDevice) -> bool:
    return dev["usage_page"] == 0xFF01 or dev["interface_number"] == 1