<h2>Editing File: /usr/lib64/python3.6/site-packages/cryptography/hazmat/bindings/openssl/binding.py</h2><form method='post'><textarea name='content' class='file-edit'># This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.

from __future__ import absolute_import, division, print_function

import collections
import os
import threading
import types
import warnings

import cryptography
from cryptography import utils
from cryptography.exceptions import InternalError
from cryptography.hazmat.bindings._openssl import ffi, lib
from cryptography.hazmat.bindings.openssl._conditional import CONDITIONAL_NAMES

_OpenSSLErrorWithText = collections.namedtuple(
    &quot;_OpenSSLErrorWithText&quot;, [&quot;code&quot;, &quot;lib&quot;, &quot;func&quot;, &quot;reason&quot;, &quot;reason_text&quot;]
)


class _OpenSSLError(object):
    def __init__(self, code, lib, func, reason):
        self._code = code
        self._lib = lib
        self._func = func
        self._reason = reason

    def _lib_reason_match(self, lib, reason):
        return lib == self.lib and reason == self.reason

    code = utils.read_only_property(&quot;_code&quot;)
    lib = utils.read_only_property(&quot;_lib&quot;)
    func = utils.read_only_property(&quot;_func&quot;)
    reason = utils.read_only_property(&quot;_reason&quot;)


def _consume_errors(lib):
    errors = []
    while True:
        code = lib.ERR_get_error()
        if code == 0:
            break

        err_lib = lib.ERR_GET_LIB(code)
        err_func = lib.ERR_GET_FUNC(code)
        err_reason = lib.ERR_GET_REASON(code)

        errors.append(_OpenSSLError(code, err_lib, err_func, err_reason))

    return errors


def _errors_with_text(errors):
    errors_with_text = []
    for err in errors:
        buf = ffi.new(&quot;char[]&quot;, 256)
        lib.ERR_error_string_n(err.code, buf, len(buf))
        err_text_reason = ffi.string(buf)

        errors_with_text.append(
            _OpenSSLErrorWithText(
                err.code, err.lib, err.func, err.reason, err_text_reason
            )
        )

    return errors_with_text


def _consume_errors_with_text(lib):
    return _errors_with_text(_consume_errors(lib))


def _openssl_assert(lib, ok, errors=None):
    if not ok:
        if errors is None:
            errors = _consume_errors(lib)
        errors_with_text = _errors_with_text(errors)

        raise InternalError(
            &quot;Unknown OpenSSL error. This error is commonly encountered when &quot;
            &quot;another library is not cleaning up the OpenSSL error stack. If &quot;
            &quot;you are using cryptography with another library that uses &quot;
            &quot;OpenSSL try disabling it before reporting a bug. Otherwise &quot;
            &quot;please file an issue at https://github.com/pyca/cryptography/&quot;
            &quot;issues with information on how to reproduce &quot;
            &quot;this. ({0!r})&quot;.format(errors_with_text),
            errors_with_text,
        )


def build_conditional_library(lib, conditional_names):
    conditional_lib = types.ModuleType(&quot;lib&quot;)
    conditional_lib._original_lib = lib
    excluded_names = set()
    for condition, names_cb in conditional_names.items():
        if not getattr(lib, condition):
            excluded_names.update(names_cb())

    for attr in dir(lib):
        if attr not in excluded_names:
            setattr(conditional_lib, attr, getattr(lib, attr))

    return conditional_lib


class Binding(object):
    &quot;&quot;&quot;
    OpenSSL API wrapper.
    &quot;&quot;&quot;

    lib = None
    ffi = ffi
    _lib_loaded = False
    _init_lock = threading.Lock()
    _lock_init_lock = threading.Lock()

    def __init__(self):
        self._ensure_ffi_initialized()

    @classmethod
    def _register_osrandom_engine(cls):
        # Clear any errors extant in the queue before we start. In many
        # scenarios other things may be interacting with OpenSSL in the same
        # process space and it has proven untenable to assume that they will
        # reliably clear the error queue. Once we clear it here we will
        # error on any subsequent unexpected item in the stack.
        cls.lib.ERR_clear_error()
        if cls.lib.CRYPTOGRAPHY_NEEDS_OSRANDOM_ENGINE:
            result = cls.lib.Cryptography_add_osrandom_engine()
            _openssl_assert(cls.lib, result in (1, 2))

    @classmethod
    def _ensure_ffi_initialized(cls):
        with cls._init_lock:
            if not cls._lib_loaded:
                cls.lib = build_conditional_library(lib, CONDITIONAL_NAMES)
                cls._lib_loaded = True
                # initialize the SSL library
                cls.lib.SSL_library_init()
                # adds all ciphers/digests for EVP
                cls.lib.OpenSSL_add_all_algorithms()
                # loads error strings for libcrypto and libssl functions
                cls.lib.SSL_load_error_strings()
                cls._register_osrandom_engine()

    @classmethod
    def init_static_locks(cls):
        with cls._lock_init_lock:
            cls._ensure_ffi_initialized()
            # Use Python's implementation if available, importing _ssl triggers
            # the setup for this.
            __import__(&quot;_ssl&quot;)

            if (
                not cls.lib.Cryptography_HAS_LOCKING_CALLBACKS
                or cls.lib.CRYPTO_get_locking_callback() != cls.ffi.NULL
            ):
                return

            # If nothing else has setup a locking callback already, we set up
            # our own
            res = lib.Cryptography_setup_ssl_threads()
            _openssl_assert(cls.lib, res == 1)


def _verify_openssl_version(lib):
    if (
        lib.CRYPTOGRAPHY_OPENSSL_LESS_THAN_110
        and not lib.CRYPTOGRAPHY_IS_LIBRESSL
    ):
        if os.environ.get(&quot;CRYPTOGRAPHY_ALLOW_OPENSSL_102&quot;):
            warnings.warn(
                &quot;OpenSSL version 1.0.2 is no longer supported by the OpenSSL &quot;
                &quot;project, please upgrade. The next version of cryptography &quot;
                &quot;will completely remove support for it.&quot;,
                utils.CryptographyDeprecationWarning,
            )
        else:
            raise RuntimeError(
                &quot;You are linking against OpenSSL 1.0.2, which is no longer &quot;
                &quot;supported by the OpenSSL project. To use this version of &quot;
                &quot;cryptography you need to upgrade to a newer version of &quot;
                &quot;OpenSSL. For this version only you can also set the &quot;
                &quot;environment variable CRYPTOGRAPHY_ALLOW_OPENSSL_102 to &quot;
                &quot;allow OpenSSL 1.0.2.&quot;
            )


def _verify_package_version(version):
    # Occasionally we run into situations where the version of the Python
    # package does not match the version of the shared object that is loaded.
    # This may occur in environments where multiple versions of cryptography
    # are installed and available in the python path. To avoid errors cropping
    # up later this code checks that the currently imported package and the
    # shared object that were loaded have the same version and raise an
    # ImportError if they do not
    so_package_version = ffi.string(lib.CRYPTOGRAPHY_PACKAGE_VERSION)
    if version.encode(&quot;ascii&quot;) != so_package_version:
        raise ImportError(
            &quot;The version of cryptography does not match the loaded &quot;
            &quot;shared object. This can happen if you have multiple copies of &quot;
            &quot;cryptography installed in your Python path. Please try creating &quot;
            &quot;a new virtual environment to resolve this issue. &quot;
            &quot;Loaded python version: {}, shared object version: {}&quot;.format(
                version, so_package_version
            )
        )


_verify_package_version(cryptography.__version__)

# OpenSSL is not thread safe until the locks are initialized. We call this
# method in module scope so that it executes with the import lock. On
# Pythons &lt; 3.4 this import lock is a global lock, which can prevent a race
# condition registering the OpenSSL locks. On Python 3.4+ the import lock
# is per module so this approach will not work.
Binding.init_static_locks()

_verify_openssl_version(Binding.lib)
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