125 lines
3.5 KiB
Python
125 lines
3.5 KiB
Python
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import os
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import sys
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import warnings
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from typing import Any, Callable, NoReturn, Type, Union
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from cryptography.hazmat.bindings.openssl.binding import Binding
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StrOrBytesPath = Union[str, bytes, os.PathLike]
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binding = Binding()
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ffi = binding.ffi
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lib = binding.lib
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# This is a special CFFI allocator that does not bother to zero its memory
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# after allocation. This has vastly better performance on large allocations and
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# so should be used whenever we don't need the memory zeroed out.
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no_zero_allocator = ffi.new_allocator(should_clear_after_alloc=False)
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def text(charp: Any) -> str:
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"""
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Get a native string type representing of the given CFFI ``char*`` object.
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:param charp: A C-style string represented using CFFI.
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:return: :class:`str`
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"""
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if not charp:
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return ""
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return ffi.string(charp).decode("utf-8")
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def exception_from_error_queue(exception_type: Type[Exception]) -> NoReturn:
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"""
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Convert an OpenSSL library failure into a Python exception.
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When a call to the native OpenSSL library fails, this is usually signalled
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by the return value, and an error code is stored in an error queue
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associated with the current thread. The err library provides functions to
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obtain these error codes and textual error messages.
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"""
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errors = []
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while True:
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error = lib.ERR_get_error()
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if error == 0:
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break
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errors.append(
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(
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text(lib.ERR_lib_error_string(error)),
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text(lib.ERR_func_error_string(error)),
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text(lib.ERR_reason_error_string(error)),
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)
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)
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raise exception_type(errors)
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def make_assert(error: Type[Exception]) -> Callable[[bool], Any]:
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"""
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Create an assert function that uses :func:`exception_from_error_queue` to
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raise an exception wrapped by *error*.
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"""
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def openssl_assert(ok: bool) -> None:
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"""
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If *ok* is not True, retrieve the error from OpenSSL and raise it.
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"""
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if ok is not True:
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exception_from_error_queue(error)
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return openssl_assert
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def path_bytes(s: StrOrBytesPath) -> bytes:
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"""
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Convert a Python path to a :py:class:`bytes` for the path which can be
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passed into an OpenSSL API accepting a filename.
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:param s: A path (valid for os.fspath).
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:return: An instance of :py:class:`bytes`.
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"""
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b = os.fspath(s)
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if isinstance(b, str):
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return b.encode(sys.getfilesystemencoding())
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else:
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return b
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def byte_string(s: str) -> bytes:
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return s.encode("charmap")
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# A marker object to observe whether some optional arguments are passed any
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# value or not.
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UNSPECIFIED = object()
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_TEXT_WARNING = "str for {0} is no longer accepted, use bytes"
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def text_to_bytes_and_warn(label: str, obj: Any) -> Any:
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"""
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If ``obj`` is text, emit a warning that it should be bytes instead and try
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to convert it to bytes automatically.
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:param str label: The name of the parameter from which ``obj`` was taken
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(so a developer can easily find the source of the problem and correct
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it).
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:return: If ``obj`` is the text string type, a ``bytes`` object giving the
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UTF-8 encoding of that text is returned. Otherwise, ``obj`` itself is
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returned.
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"""
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if isinstance(obj, str):
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warnings.warn(
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_TEXT_WARNING.format(label),
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category=DeprecationWarning,
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stacklevel=3,
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)
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return obj.encode("utf-8")
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return obj
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