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

138 lines
4.3 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 importlib
import logging
from typing import Iterable, Type
LOG = logging.getLogger(__name__)
class TransportException(Exception):
pass
class Transport(object):
def __init__(self):
self.session_counter = 0
def __str__(self):
return self.get_path()
def get_path(self):
return "{}:{}".format(self.PATH_PREFIX, self.device)
def session_begin(self):
if self.session_counter == 0:
self.open()
self.session_counter += 1
def session_end(self):
self.session_counter = max(self.session_counter - 1, 0)
if self.session_counter == 0:
self.close()
def open(self):
raise NotImplementedError
def close(self):
raise NotImplementedError
@classmethod
def enumerate(cls):
raise NotImplementedError
@classmethod
def find_by_path(cls, path, prefix_search=False):
for device in cls.enumerate():
if (
path is None
or device.get_path() == path
or (prefix_search and device.get_path().startswith(path))
):
return device
raise TransportException(
"{} device not found: {}".format(cls.PATH_PREFIX, path)
)
def all_transports() -> Iterable[Type[Transport]]:
transports = set() # type: Set[Type[Transport]]
for modname in ("bridge", "hid", "udp", "webusb"):
try:
# Import the module and find the Transport class.
# To avoid iterating over every item, the module should assign its Transport class
# to a constant named TRANSPORT.
module = importlib.import_module("." + modname, __name__)
try:
transports.add(getattr(module, "TRANSPORT"))
except AttributeError:
LOG.warning("Skipping broken module {}".format(modname))
except ImportError as e:
LOG.info("Failed to import module {}: {}".format(modname, e))
return transports
def enumerate_devices() -> Iterable[Transport]:
devices = [] # type: List[Transport]
for transport in all_transports():
try:
found = transport.enumerate()
LOG.info(
"Enumerating {}: found {} devices".format(
transport.__name__, len(found)
)
)
devices.extend(found)
except NotImplementedError:
LOG.error(
"{} does not implement device enumeration".format(transport.__name__)
)
except Exception as e:
LOG.error(
"Failed to enumerate {}. {}: {}".format(
transport.__name__, e.__class__.__name__, e
)
)
return devices
def get_transport(path: str = None, prefix_search: bool = False) -> Transport:
if path is None:
try:
return next(iter(enumerate_devices()))
except IndexError:
raise Exception("No TREZOR device found") from None
# Find whether B is prefix of A (transport name is part of the path)
# or A is prefix of B (path is a prefix, or a name, of transport).
# This naively expects that no two transports have a common prefix.
def match_prefix(a: str, b: str) -> bool:
return a.startswith(b) or b.startswith(a)
LOG.info(
"looking for device by {}: {}".format(
"prefix" if prefix_search else "full path", path
)
)
transports = [t for t in all_transports() if match_prefix(path, t.PATH_PREFIX)]
if transports:
return transports[0].find_by_path(path, prefix_search=prefix_search)
raise Exception("Could not find device by path: {}".format(path))