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# Copyright 2016-2018 Yubico AB
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import abc
import re
from typing import Optional
from urllib import parse
class YhsmBackend(abc.ABC):
"""Provides low-level communication with a YubiHSM."""
@abc.abstractmethod
def transceive(self, msg: bytes) -> bytes:
"""Send a verbatim message."""
@abc.abstractmethod
def close(self) -> None:
"""Closes the connection to the YubiHSM."""
def get_backend(url: Optional[str] = None) -> YhsmBackend:
"""Returns a backend suitable for the given URL."""
url = url or "http://localhost:12345"
parsed = parse.urlparse(url)
try:
if parsed.scheme == "yhusb":
from .usb import UsbBackend
serial = re.match(r"serial=(\d+)", parsed.netloc)
if serial:
return UsbBackend(serial=int(serial.group(1)), timeout=600)
elif not parsed.netloc: # On anything else, fall through to error.
return UsbBackend(serial=None, timeout=600)
elif parsed.scheme in ("http", "https"):
from .http import HttpBackend
return HttpBackend(url, (10, 600))
except ImportError:
raise ValueError(
'Unable to initialize backend for scheme "%s", are '
"required dependencies installed?" % parsed.scheme
)
raise ValueError("Invalid YubiHSM backend URL.")
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