Edit: binding.py
# 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( "_OpenSSLErrorWithText", ["code", "lib", "func", "reason", "reason_text"] ) 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("_code") lib = utils.read_only_property("_lib") func = utils.read_only_property("_func") reason = utils.read_only_property("_reason") 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("char[]", 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( "Unknown OpenSSL error. This error is commonly encountered when " "another library is not cleaning up the OpenSSL error stack. If " "you are using cryptography with another library that uses " "OpenSSL try disabling it before reporting a bug. Otherwise " "please file an issue at https://github.com/pyca/cryptography/" "issues with information on how to reproduce " "this. ({0!r})".format(errors_with_text), errors_with_text, ) def build_conditional_library(lib, conditional_names): conditional_lib = types.ModuleType("lib") 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): """ OpenSSL API wrapper. """ 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__("_ssl") 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("CRYPTOGRAPHY_ALLOW_OPENSSL_102"): warnings.warn( "OpenSSL version 1.0.2 is no longer supported by the OpenSSL " "project, please upgrade. The next version of cryptography " "will completely remove support for it.", utils.CryptographyDeprecationWarning, ) else: raise RuntimeError( "You are linking against OpenSSL 1.0.2, which is no longer " "supported by the OpenSSL project. To use this version of " "cryptography you need to upgrade to a newer version of " "OpenSSL. For this version only you can also set the " "environment variable CRYPTOGRAPHY_ALLOW_OPENSSL_102 to " "allow OpenSSL 1.0.2." ) 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("ascii") != so_package_version: raise ImportError( "The version of cryptography does not match the loaded " "shared object. This can happen if you have multiple copies of " "cryptography installed in your Python path. Please try creating " "a new virtual environment to resolve this issue. " "Loaded python version: {}, shared object version: {}".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 < 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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