Merge pull request #226 from matejcik/refactor-transport-nicediff

prefix search for `trezorctl -p`

setup.py

@@ -33,6 +33,7 @@ setup(
     url='https://github.com/trezor/python-trezor',
     packages=[
         'trezorlib',
+        'trezorlib.transport',
         'trezorlib.messages',
         'trezorlib.qt',
         'trezorlib.tests.device_tests',

tools/encfs_aes_getpass.py

@@ -16,21 +16,15 @@ import hashlib
 import binascii
 
 from trezorlib.client import TrezorClient
-from trezorlib.device import TrezorDevice
+from trezorlib.transport import enumerate_devices
-
-# Python2 vs Python3
-try:
-    input = raw_input
-except NameError:
-    pass
 
 
 def wait_for_devices():
-    devices = TrezorDevice.enumerate()
+    devices = enumerate_devices()
     while not len(devices):
         sys.stderr.write("Please connect TREZOR to computer and press Enter...")
         input()
-        devices = TrezorDevice.enumerate()
+        devices = enumerate_devices()
 
     return devices
 

tools/helloworld.py

@@ -1,21 +1,11 @@
 #!/usr/bin/env python3
-from __future__ import print_function
-
 from trezorlib.client import TrezorClient
-from trezorlib.device import TrezorDevice
+from trezorlib.transport import get_transport
 
 
 def main():
-    # List all connected TREZORs on USB/UDP
-    devices = TrezorDevice.enumerate()
-
-    # Check whether we found any
-    if len(devices) == 0:
-        print('No TREZOR found')
-        return
-
     # Use first connected device
-    transport = devices[0]
+    transport = get_transport()
 
     # Creates object for manipulating TREZOR
     client = TrezorClient(transport)

tools/mem_flashblock.py

@@ -1,9 +1,7 @@
 #!/usr/bin/env python3
-from __future__ import print_function
-
 from trezorlib.debuglink import DebugLink
 from trezorlib.client import TrezorClient
-from trezorlib.transport_hid import HidTransport
+from trezorlib.transport import enumerate_devices
 import binascii
 import sys
 
@@ -16,8 +14,8 @@ sectorlens = [0x4000, 0x4000, 0x4000, 0x4000,
 
 
 def main():
-    # List all connected TREZORs on USB
+    # List all debuggable TREZORs
-    devices = HidTransport.enumerate()
+    devices = [device for device in enumerate_devices() if hasattr(device, 'find_debug')]
 
     # Check whether we found any
     if len(devices) == 0:

tools/mem_read.py

@@ -1,9 +1,7 @@
 #!/usr/bin/env python3
-from __future__ import print_function
-
 from trezorlib.debuglink import DebugLink
 from trezorlib.client import TrezorClient
-from trezorlib.transport_hid import HidTransport
+from trezorlib.transport import enumerate_devices
 import sys
 
 # usage examples
@@ -16,8 +14,8 @@ import sys
 
 
 def main():
-    # List all connected TREZORs on USB
+    # List all debuggable TREZORs
-    devices = HidTransport.enumerate()
+    devices = [device for device in enumerate_devices() if hasattr(device, 'find_debug')]
 
     # Check whether we found any
     if len(devices) == 0:

tools/mem_write.py

@@ -1,16 +1,14 @@
 #!/usr/bin/env python3
-from __future__ import print_function
-
 from trezorlib.debuglink import DebugLink
 from trezorlib.client import TrezorClient
-from trezorlib.transport_hid import HidTransport
+from trezorlib.transport import enumerate_devices
 import binascii
 import sys
 
 
 def main():
-    # List all connected TREZORs on USB
+    # List all debuggable TREZORs
-    devices = HidTransport.enumerate()
+    devices = [device for device in enumerate_devices() if hasattr(device, 'find_debug')]
 
     # Check whether we found any
     if len(devices) == 0:

tools/mnemonic_check.py

@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-from __future__ import print_function
 import binascii
 import hashlib
 import mnemonic
@@ -16,12 +15,6 @@ __doc__ = '''
     without an internet connection).
 '''
 
-# Python2 vs Python3
-try:
-    input = raw_input
-except NameError:
-    pass
-
 
 def generate_entropy(strength, internal_entropy, external_entropy):
     '''

tools/pwd_reader.py

@@ -1,7 +1,4 @@
 #!/usr/bin/env python3
-
-from __future__ import print_function
-
 from binascii import hexlify, unhexlify
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
 from cryptography.hazmat.backends import default_backend
@@ -9,14 +6,10 @@ import hmac
 import hashlib
 import json
 import os
-try:
+from urllib.parse import urlparse
-    from urllib.parse import urlparse
-except:
-    from urlparse import urlparse
-    input = raw_input
 
 from trezorlib.client import TrezorClient
-from trezorlib.transport_hid import HidTransport
+from trezorlib.transport import get_transport
 
 
 # Return path by BIP-32
@@ -132,12 +125,13 @@ def printEntries(entries):
 
 
 def main():
-    devices = HidTransport.enumerate()
+    try:
-    if not devices:
+        transport = get_transport()
-        print('TREZOR is not plugged in. Please, connect TREZOR and retry.')
+    except Exception as e:
+        print(e)
         return
 
-    client = TrezorClient(devices[0])
+    client = TrezorClient(transport)
 
     print()
     print('Confirm operation on TREZOR')

tools/rng_entropy_collector.py

@@ -8,21 +8,14 @@ from __future__ import print_function
 import io
 import sys
 from trezorlib.client import TrezorClient
-from trezorlib.device import TrezorDevice
+from trezorlib.transport import get_transport
-
-
-def get_client():
-    devices = TrezorDevice.enumerate()    # list all connected TREZORs on USB
-    if len(devices) == 0:                 # check whether we found any
-        return None
-    transport = devices[0]                # use first connected device
-    return TrezorClient(transport)        # creates object for communicating with TREZOR
 
 
 def main():
-    client = get_client()
+    try:
-    if not client:
+        client = TrezorClient(get_transport())
-        print('No TREZOR connected')
+    except Exception as e:
+        print(e)
         return
 
     arg1 = sys.argv[1]                     # output file

tools/signtest.py

@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-from __future__ import print_function
 import binascii
 import os
 import random
@@ -12,8 +11,7 @@ import hashlib
 from trezorlib.client import TrezorClient
 from trezorlib.tx_api import TxApiTestnet
 from trezorlib.tx_api import TxApiBitcoin
-from trezorlib.transport_hid import HidTransport
+from trezorlib.transport import get_transport
-from trezorlib.transport_bridge import BridgeTransport
 
 
 def hash160(x):
@@ -152,16 +150,13 @@ def main():
     numinputs = 100
     sizeinputtx = 10
 
-    # List all connected TREZORs on USB
+    # Use first connected device
-    devices = HidTransport.enumerate()
+    try:
-
+        transport = get_transport()
-    # Check whether we found any
+    except Exception as e:
-    if len(devices) == 0:
+        print(e)
-        print('No TREZOR found')
         return
 
-    # Use first connected device
-    transport = devices[0]
     print(transport)
 
     txstore = MyTxApiBitcoin()

trezorctl

@@ -29,7 +29,7 @@ import os
 import sys
 
 from trezorlib.client import TrezorClient, TrezorClientVerbose, CallException, format_protobuf
-from trezorlib.device import TrezorDevice
+from trezorlib.transport import get_transport, enumerate_devices, TransportException
 from trezorlib import messages as proto
 from trezorlib import protobuf
 from trezorlib.coins import coins_txapi
@@ -72,9 +72,24 @@ CHOICE_OUTPUT_SCRIPT_TYPE = ChoiceType({
 def cli(ctx, path, verbose, is_json):
     if ctx.invoked_subcommand != 'list':
         if verbose:
-            ctx.obj = lambda: TrezorClientVerbose(TrezorDevice.find_by_path(path))
+            cls = TrezorClientVerbose
         else:
-            ctx.obj = lambda: TrezorClient(TrezorDevice.find_by_path(path))
+            cls = TrezorClient
+
+        def get_device():
+            try:
+                device = get_transport(path, prefix_search=False)
+            except:
+                try:
+                    device = get_transport(path, prefix_search=True)
+                except:
+                    click.echo("Failed to find a TREZOR device.")
+                    if path is not None:
+                        click.echo("Using path: {}".format(path))
+                    sys.exit(1)
+            return cls(device)
+
+        ctx.obj = get_device
 
 
 @cli.resultcallback()
@@ -108,7 +123,7 @@ def print_result(res, path, verbose, is_json):
 
 @cli.command(name='list', help='List connected TREZOR devices.')
 def ls():
-    return TrezorDevice.enumerate()
+    return enumerate_devices()
 
 
 @cli.command(help='Show version of trezorctl/trezorlib.')

trezorlib/device.py

@@ -16,53 +16,24 @@
 # 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/>.
 
+import warnings
 
-from .transport_bridge import BridgeTransport
+from .transport import enumerate_devices, get_transport
-from .transport_hid import HidTransport
-from .transport_udp import UdpTransport
-from .transport_webusb import WebUsbTransport
 
 
-class TrezorDevice(object):
+class TrezorDevice:
+    '''
+    This class is deprecated. (There is no reason for it to exist in the first
+    place, it is nothing but a collection of two functions.)
+    Instead, please use functions from the ``trezorlib.transport`` module.
+    '''
 
     @classmethod
     def enumerate(cls):
-        devices = []
+        warnings.warn('TrezorDevice is deprecated.', DeprecationWarning)
-
+        return enumerate_devices()
-        for d in BridgeTransport.enumerate():
-            devices.append(d)
-
-        for d in UdpTransport.enumerate():
-            devices.append(d)
-
-        for d in HidTransport.enumerate():
-            devices.append(d)
-
-        for d in WebUsbTransport.enumerate():
-            devices.append(d)
-
-        return devices
 
     @classmethod
     def find_by_path(cls, path):
-        if path is None:
+        warnings.warn('TrezorDevice is deprecated.', DeprecationWarning)
-            try:
+        return get_transport(path, prefix_search=False)
-                return cls.enumerate()[0]
-            except IndexError:
-                raise Exception("No TREZOR device found")
-
-        prefix = path.split(':')[0]
-
-        if prefix == BridgeTransport.PATH_PREFIX:
-            return BridgeTransport.find_by_path(path)
-
-        if prefix == UdpTransport.PATH_PREFIX:
-            return UdpTransport.find_by_path(path)
-
-        if prefix == WebUsbTransport.PATH_PREFIX:
-            return WebUsbTransport.find_by_path(path)
-
-        if prefix == HidTransport.PATH_PREFIX:
-            return HidTransport.find_by_path(path)
-
-        raise Exception("Unknown path prefix '%s'" % prefix)

trezorlib/tests/device_tests/common.py

@@ -23,86 +23,23 @@ import pytest
 import os
 
 from trezorlib.client import TrezorClient, TrezorClientDebugLink
+from trezorlib.transport import get_transport
 from trezorlib import tx_api
 
 tests_dir = os.path.dirname(os.path.abspath(__file__))
 tx_api.cache_dir = os.path.join(tests_dir, '../txcache')
 
 
-try:
+def get_device():
-    from trezorlib.transport_hid import HidTransport
+    path = os.environ.get('TREZOR_PATH')
-    HID_ENABLED = True
+    return get_transport(path)
-except ImportError as e:
-    print('HID transport disabled:', e)
-    HID_ENABLED = False
-
-try:
-    from trezorlib.transport_webusb import WebUsbTransport
-    WEBUSB_ENABLED = True
-except ImportError as e:
-    print('WebUSB transport disabled:', e)
-    WEBUSB_ENABLED = False
-
-try:
-    from trezorlib.transport_pipe import PipeTransport
-    PIPE_ENABLED = True
-except ImportError as e:
-    print('PIPE transport disabled:', e)
-    PIPE_ENABLED = False
-
-try:
-    from trezorlib.transport_udp import UdpTransport
-    UDP_ENABLED = True
-except ImportError as e:
-    print('UDP transport disabled:', e)
-    UDP_ENABLED = False
 
 
-def pipe_exists(path):
+class TrezorTest:
-    import os
-    import stat
-    try:
-        return stat.S_ISFIFO(os.stat(path).st_mode)
-    except:
-        return False
-
-
-def get_transport():
-    if HID_ENABLED and HidTransport.enumerate():
-        devices = HidTransport.enumerate()
-        wirelink = devices[0]
-        debuglink = devices[0].find_debug()
-
-    elif WEBUSB_ENABLED and WebUsbTransport.enumerate():
-        devices = WebUsbTransport.enumerate()
-        wirelink = devices[0]
-        debuglink = devices[0].find_debug()
-
-    elif PIPE_ENABLED and pipe_exists('/tmp/pipe.trezor.to'):
-        wirelink = PipeTransport('/tmp/pipe.trezor', False)
-        debuglink = PipeTransport('/tmp/pipe.trezor_debug', False)
-
-    elif UDP_ENABLED:
-        wirelink = UdpTransport('127.0.0.1:21324')
-        debuglink = UdpTransport('127.0.0.1:21325')
-
-    return wirelink, debuglink
-
-
-if HID_ENABLED and HidTransport.enumerate():
-    print('Using TREZOR')
-elif WEBUSB_ENABLED and WebUsbTransport.enumerate():
-    print('Using TREZOR via WebUSB')
-elif PIPE_ENABLED and pipe_exists('/tmp/pipe.trezor.to'):
-    print('Using Emulator (v1=pipe)')
-elif UDP_ENABLED:
-    print('Using Emulator (v2=udp)')
-
-
-class TrezorTest(object):
 
     def setup_method(self, method):
-        wirelink, debuglink = get_transport()
+        wirelink = get_device()
+        debuglink = wirelink.find_debug()
         self.client = TrezorClientDebugLink(wirelink)
         self.client.set_debuglink(debuglink)
         self.client.set_tx_api(tx_api.TxApiBitcoin)

trezorlib/transport.py

@@ -1,46 +0,0 @@
-# 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>
-# Copyright (C) 2016      Jochen Hoenicke <hoenicke@gmail.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
-
-
-class TransportException(Exception):
-    pass
-
-
-class Transport(object):
-
-    def __init__(self):
-        self.session_counter = 0
-
-    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

trezorlib/transport/__init__.py

@@ -0,0 +1,97 @@
+# 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>
+# Copyright (C) 2016      Jochen Hoenicke <hoenicke@gmail.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/>.
+
+
+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():
+    from .bridge import BridgeTransport
+    from .hid import HidTransport
+    from .udp import UdpTransport
+    from .webusb import WebUsbTransport
+    return (BridgeTransport, HidTransport, UdpTransport, WebUsbTransport)
+
+
+def enumerate_devices():
+    return [device
+            for transport in all_transports()
+            for device in transport.enumerate()]
+
+
+def get_transport(path=None, prefix_search=False):
+    if path is None:
+        try:
+            return enumerate_devices()[0]
+        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, b):
+        return a.startswith(b) or b.startswith(a)
+
+    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("Unknown path prefix '%s'" % prefix)

trezorlib/transport/bridge.py

@@ -17,17 +17,15 @@
 # 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
-
 import requests
 import binascii
 from io import BytesIO
 import struct
 
-from . import mapping
+from .. import mapping
-from . import messages
+from .. import messages
-from . import protobuf
+from .. import protobuf
-from .transport import Transport, TransportException
+from . import Transport, TransportException
 
 TREZORD_HOST = 'http://127.0.0.1:21325'
 
@@ -45,16 +43,13 @@ class BridgeTransport(Transport):
     HEADERS = {'Origin': 'https://python.trezor.io'}
 
     def __init__(self, device):
-        super(BridgeTransport, self).__init__()
+        super().__init__()
 
         self.device = device
         self.conn = requests.Session()
         self.session = None
         self.response = None
 
-    def __str__(self):
-        return self.get_path()
-
     def get_path(self):
         return '%s:%s' % (self.PATH_PREFIX, self.device['path'])
 
@@ -68,17 +63,6 @@ class BridgeTransport(Transport):
         except:
             return []
 
-    @classmethod
-    def find_by_path(cls, path):
-        if isinstance(path, bytes):
-            path = path.decode()
-        path = path.replace('%s:' % cls.PATH_PREFIX, '')
-
-        for transport in BridgeTransport.enumerate():
-            if path is None or transport.device['path'] == path:
-                return transport
-        raise TransportException('Bridge device not found')
-
     def open(self):
         r = self.conn.post(TREZORD_HOST + '/acquire/%s/null' % self.device['path'], headers=self.HEADERS)
         if r.status_code != 200:

trezorlib/transport/hid.py

@@ -16,22 +16,20 @@
 # 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
-
 import time
 import hid
 import os
 
-from .protocol_v1 import ProtocolV1
+from ..protocol_v1 import ProtocolV1
-from .protocol_v2 import ProtocolV2
+from ..protocol_v2 import ProtocolV2
-from .transport import Transport, TransportException
+from . import Transport, TransportException
 
 DEV_TREZOR1 = (0x534c, 0x0001)
 DEV_TREZOR2 = (0x1209, 0x53c1)
 DEV_TREZOR2_BL = (0x1209, 0x53c0)
 
 
-class HidHandle(object):
+class HidHandle:
 
     def __init__(self, path):
         self.path = path
@@ -79,9 +77,6 @@ class HidTransport(Transport):
         self.hid = hid_handle
         self.hid_version = None
 
-    def __str__(self):
-        return self.get_path()
-
     def get_path(self):
         return "%s:%s" % (self.PATH_PREFIX, self.device['path'].decode())
 
@@ -100,17 +95,6 @@ class HidTransport(Transport):
             devices.append(HidTransport(dev))
         return devices
 
-    @classmethod
-    def find_by_path(cls, path):
-        if isinstance(path, str):
-            path = path.encode()
-        path = path.replace(b'%s:' % cls.PATH_PREFIX.encode(), b'')
-
-        for transport in HidTransport.enumerate():
-            if path is None or transport.device['path'] == path:
-                return transport
-        raise TransportException('HID device not found')
-
     def find_debug(self):
         if isinstance(self.protocol, ProtocolV2):
             # For v2 protocol, lets use the same HID interface, but with a different session

trezorlib/transport/udp.py

@@ -16,14 +16,12 @@
 # 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
-
 import os
 import socket
 
-from .protocol_v1 import ProtocolV1
+from ..protocol_v1 import ProtocolV1
-from .protocol_v2 import ProtocolV2
+from ..protocol_v2 import ProtocolV2
-from .transport import Transport, TransportException
+from . import Transport, TransportException
 
 
 class UdpTransport(Transport):
@@ -48,26 +46,41 @@ class UdpTransport(Transport):
         self.protocol = protocol
         self.socket = None
 
-    def __str__(self):
-        return self.get_path()
-
     def get_path(self):
         return "%s:%s:%s" % ((self.PATH_PREFIX,) + self.device)
 
-    @staticmethod
+    def find_debug(self):
-    def enumerate():
+        host, port = self.device
-        devices = []
+        return UdpTransport('{}:{}'.format(host, port + 1), self.protocol)
-        d = UdpTransport("%s:%d" % (UdpTransport.DEFAULT_HOST, UdpTransport.DEFAULT_PORT))
-        d.open()
-        if d._ping():
-            devices.append(d)
-        d.close()
-        return devices
 
     @classmethod
-    def find_by_path(cls, path):
+    def _try_path(cls, path):
-        path = path.replace('%s:' % cls.PATH_PREFIX, '')
+        d = cls(path)
-        return UdpTransport(path)
+        try:
+            d.open()
+            if d._ping():
+                return d
+            else:
+                raise TransportException('No TREZOR device found at address {}'.format(path))
+        finally:
+            d.close()
+
+    @classmethod
+    def enumerate(cls):
+        devices = []
+        default_path = '{}:{}'.format(cls.DEFAULT_HOST, cls.DEFAULT_PORT)
+        try:
+            return [cls._try_path(default_path)]
+        except TransportException:
+            return []
+
+    @classmethod
+    def find_by_path(cls, path, prefix_search=False):
+        if prefix_search:
+            return super().find_by_path(path, prefix_search)
+        else:
+            path = path.replace('{}:'.format(cls.PATH_PREFIX), '')
+            return cls._try_path(path)
 
     def open(self):
         self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

trezorlib/transport/webusb.py

@@ -16,16 +16,14 @@
 # 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
-
 import time
 import os
 import atexit
 import usb1
 
-from .protocol_v1 import ProtocolV1
+from ..protocol_v1 import ProtocolV1
-from .protocol_v2 import ProtocolV2
+from ..protocol_v2 import ProtocolV2
-from .transport import Transport, TransportException
+from . import Transport, TransportException
 
 DEV_TREZOR1 = (0x534c, 0x0001)
 DEV_TREZOR2 = (0x1209, 0x53c1)
@@ -37,7 +35,7 @@ DEBUG_INTERFACE = 1
 DEBUG_ENDPOINT = 2
 
 
-class WebUsbHandle(object):
+class WebUsbHandle:
 
     def __init__(self, device):
         self.device = device
@@ -88,9 +86,6 @@ class WebUsbTransport(Transport):
         self.handle = handle
         self.debug = debug
 
-    def __str__(self):
-        return self.get_path()
-
     def get_path(self):
         return "%s:%s" % (self.PATH_PREFIX, dev_to_str(self.device))
 
@@ -106,17 +101,18 @@ class WebUsbTransport(Transport):
                 continue
             if not is_vendor_class(dev):
                 continue
-            devices.append(WebUsbTransport(dev))
+            try:
+                # workaround for issue #223:
+                # on certain combinations of Windows USB drivers and libusb versions,
+                # Trezor is returned twice (possibly because Windows know it as both
+                # a HID and a WebUSB device), and one of the returned devices is
+                # non-functional.
+                dev.getProduct()
+                devices.append(WebUsbTransport(dev))
+            except usb1.USBErrorNotSupported:
+                pass
         return devices
 
-    @classmethod
-    def find_by_path(cls, path):
-        path = path.replace('%s:' % cls.PATH_PREFIX, '')  # Remove prefix from __str__()
-        for transport in WebUsbTransport.enumerate():
-            if path is None or dev_to_str(transport.device) == path:
-                return transport
-        raise TransportException('WebUSB device not found')
-
     def find_debug(self):
         if isinstance(self.protocol, ProtocolV2):
             # TODO test this