Paint it Black by the Rolling Stones (#920)

1 files changed, 196 insertions, 161 deletions

diff --git a/src/OpenSSL/SSL.py b/src/OpenSSL/SSL.py
index 25308f1..b4b308f 100644
--- a/src/OpenSSL/SSL.py
+++ b/src/OpenSSL/SSL.py
@@ -23,100 +23,108 @@ from OpenSSL._util import (
 )
 
 from OpenSSL.crypto import (
-    FILETYPE_PEM, _PassphraseHelper, PKey, X509Name, X509, X509Store)
+    FILETYPE_PEM,
+    _PassphraseHelper,
+    PKey,
+    X509Name,
+    X509,
+    X509Store,
+)
 
 __all__ = [
-    'OPENSSL_VERSION_NUMBER',
-    'SSLEAY_VERSION',
-    'SSLEAY_CFLAGS',
-    'SSLEAY_PLATFORM',
-    'SSLEAY_DIR',
-    'SSLEAY_BUILT_ON',
-    'SENT_SHUTDOWN',
-    'RECEIVED_SHUTDOWN',
-    'SSLv2_METHOD',
-    'SSLv3_METHOD',
-    'SSLv23_METHOD',
-    'TLSv1_METHOD',
-    'TLSv1_1_METHOD',
-    'TLSv1_2_METHOD',
-    'OP_NO_SSLv2',
-    'OP_NO_SSLv3',
-    'OP_NO_TLSv1',
-    'OP_NO_TLSv1_1',
-    'OP_NO_TLSv1_2',
-    'OP_NO_TLSv1_3',
-    'MODE_RELEASE_BUFFERS',
-    'OP_SINGLE_DH_USE',
-    'OP_SINGLE_ECDH_USE',
-    'OP_EPHEMERAL_RSA',
-    'OP_MICROSOFT_SESS_ID_BUG',
-    'OP_NETSCAPE_CHALLENGE_BUG',
-    'OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG',
-    'OP_SSLREF2_REUSE_CERT_TYPE_BUG',
-    'OP_MICROSOFT_BIG_SSLV3_BUFFER',
-    'OP_MSIE_SSLV2_RSA_PADDING',
-    'OP_SSLEAY_080_CLIENT_DH_BUG',
-    'OP_TLS_D5_BUG',
-    'OP_TLS_BLOCK_PADDING_BUG',
-    'OP_DONT_INSERT_EMPTY_FRAGMENTS',
-    'OP_CIPHER_SERVER_PREFERENCE',
-    'OP_TLS_ROLLBACK_BUG',
-    'OP_PKCS1_CHECK_1',
-    'OP_PKCS1_CHECK_2',
-    'OP_NETSCAPE_CA_DN_BUG',
-    'OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG',
-    'OP_NO_COMPRESSION',
-    'OP_NO_QUERY_MTU',
-    'OP_COOKIE_EXCHANGE',
-    'OP_NO_TICKET',
-    'OP_ALL',
-    'VERIFY_PEER',
-    'VERIFY_FAIL_IF_NO_PEER_CERT',
-    'VERIFY_CLIENT_ONCE',
-    'VERIFY_NONE',
-    'SESS_CACHE_OFF',
-    'SESS_CACHE_CLIENT',
-    'SESS_CACHE_SERVER',
-    'SESS_CACHE_BOTH',
-    'SESS_CACHE_NO_AUTO_CLEAR',
-    'SESS_CACHE_NO_INTERNAL_LOOKUP',
-    'SESS_CACHE_NO_INTERNAL_STORE',
-    'SESS_CACHE_NO_INTERNAL',
-    'SSL_ST_CONNECT',
-    'SSL_ST_ACCEPT',
-    'SSL_ST_MASK',
-    'SSL_CB_LOOP',
-    'SSL_CB_EXIT',
-    'SSL_CB_READ',
-    'SSL_CB_WRITE',
-    'SSL_CB_ALERT',
-    'SSL_CB_READ_ALERT',
-    'SSL_CB_WRITE_ALERT',
-    'SSL_CB_ACCEPT_LOOP',
-    'SSL_CB_ACCEPT_EXIT',
-    'SSL_CB_CONNECT_LOOP',
-    'SSL_CB_CONNECT_EXIT',
-    'SSL_CB_HANDSHAKE_START',
-    'SSL_CB_HANDSHAKE_DONE',
-    'Error',
-    'WantReadError',
-    'WantWriteError',
-    'WantX509LookupError',
-    'ZeroReturnError',
-    'SysCallError',
-    'SSLeay_version',
-    'Session',
-    'Context',
-    'Connection'
+    "OPENSSL_VERSION_NUMBER",
+    "SSLEAY_VERSION",
+    "SSLEAY_CFLAGS",
+    "SSLEAY_PLATFORM",
+    "SSLEAY_DIR",
+    "SSLEAY_BUILT_ON",
+    "SENT_SHUTDOWN",
+    "RECEIVED_SHUTDOWN",
+    "SSLv2_METHOD",
+    "SSLv3_METHOD",
+    "SSLv23_METHOD",
+    "TLSv1_METHOD",
+    "TLSv1_1_METHOD",
+    "TLSv1_2_METHOD",
+    "OP_NO_SSLv2",
+    "OP_NO_SSLv3",
+    "OP_NO_TLSv1",
+    "OP_NO_TLSv1_1",
+    "OP_NO_TLSv1_2",
+    "OP_NO_TLSv1_3",
+    "MODE_RELEASE_BUFFERS",
+    "OP_SINGLE_DH_USE",
+    "OP_SINGLE_ECDH_USE",
+    "OP_EPHEMERAL_RSA",
+    "OP_MICROSOFT_SESS_ID_BUG",
+    "OP_NETSCAPE_CHALLENGE_BUG",
+    "OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG",
+    "OP_SSLREF2_REUSE_CERT_TYPE_BUG",
+    "OP_MICROSOFT_BIG_SSLV3_BUFFER",
+    "OP_MSIE_SSLV2_RSA_PADDING",
+    "OP_SSLEAY_080_CLIENT_DH_BUG",
+    "OP_TLS_D5_BUG",
+    "OP_TLS_BLOCK_PADDING_BUG",
+    "OP_DONT_INSERT_EMPTY_FRAGMENTS",
+    "OP_CIPHER_SERVER_PREFERENCE",
+    "OP_TLS_ROLLBACK_BUG",
+    "OP_PKCS1_CHECK_1",
+    "OP_PKCS1_CHECK_2",
+    "OP_NETSCAPE_CA_DN_BUG",
+    "OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG",
+    "OP_NO_COMPRESSION",
+    "OP_NO_QUERY_MTU",
+    "OP_COOKIE_EXCHANGE",
+    "OP_NO_TICKET",
+    "OP_ALL",
+    "VERIFY_PEER",
+    "VERIFY_FAIL_IF_NO_PEER_CERT",
+    "VERIFY_CLIENT_ONCE",
+    "VERIFY_NONE",
+    "SESS_CACHE_OFF",
+    "SESS_CACHE_CLIENT",
+    "SESS_CACHE_SERVER",
+    "SESS_CACHE_BOTH",
+    "SESS_CACHE_NO_AUTO_CLEAR",
+    "SESS_CACHE_NO_INTERNAL_LOOKUP",
+    "SESS_CACHE_NO_INTERNAL_STORE",
+    "SESS_CACHE_NO_INTERNAL",
+    "SSL_ST_CONNECT",
+    "SSL_ST_ACCEPT",
+    "SSL_ST_MASK",
+    "SSL_CB_LOOP",
+    "SSL_CB_EXIT",
+    "SSL_CB_READ",
+    "SSL_CB_WRITE",
+    "SSL_CB_ALERT",
+    "SSL_CB_READ_ALERT",
+    "SSL_CB_WRITE_ALERT",
+    "SSL_CB_ACCEPT_LOOP",
+    "SSL_CB_ACCEPT_EXIT",
+    "SSL_CB_CONNECT_LOOP",
+    "SSL_CB_CONNECT_EXIT",
+    "SSL_CB_HANDSHAKE_START",
+    "SSL_CB_HANDSHAKE_DONE",
+    "Error",
+    "WantReadError",
+    "WantWriteError",
+    "WantX509LookupError",
+    "ZeroReturnError",
+    "SysCallError",
+    "SSLeay_version",
+    "Session",
+    "Context",
+    "Connection",
 ]
 
 try:
     _buffer = buffer
 except NameError:
+
     class _buffer(object):
         pass
 
+
 OPENSSL_VERSION_NUMBER = _lib.OPENSSL_VERSION_NUMBER
 SSLEAY_VERSION = _lib.SSLEAY_VERSION
 SSLEAY_CFLAGS = _lib.SSLEAY_CFLAGS
@@ -199,12 +207,9 @@ if _lib.Cryptography_HAS_SSL_ST:
     SSL_ST_BEFORE = _lib.SSL_ST_BEFORE
     SSL_ST_OK = _lib.SSL_ST_OK
     SSL_ST_RENEGOTIATE = _lib.SSL_ST_RENEGOTIATE
-    __all__.extend([
-        'SSL_ST_INIT',
-        'SSL_ST_BEFORE',
-        'SSL_ST_OK',
-        'SSL_ST_RENEGOTIATE',
-    ])
+    __all__.extend(
+        ["SSL_ST_INIT", "SSL_ST_BEFORE", "SSL_ST_OK", "SSL_ST_RENEGOTIATE"]
+    )
 
 SSL_CB_LOOP = _lib.SSL_CB_LOOP
 SSL_CB_EXIT = _lib.SSL_CB_EXIT
@@ -333,7 +338,8 @@ class _VerifyHelper(_CallbackExceptionHelper):
                     return 0
 
         self.callback = _ffi.callback(
-            "int (*)(int, X509_STORE_CTX *)", wrapper)
+            "int (*)(int, X509_STORE_CTX *)", wrapper
+        )
 
 
 class _NpnAdvertiseHelper(_CallbackExceptionHelper):
@@ -352,7 +358,7 @@ class _NpnAdvertiseHelper(_CallbackExceptionHelper):
 
                 # Join the protocols into a Python bytestring, length-prefixing
                 # each element.
-                protostr = b''.join(
+                protostr = b"".join(
                     chain.from_iterable((int2byte(len(p)), p) for p in protos)
                 )
 
@@ -373,7 +379,7 @@ class _NpnAdvertiseHelper(_CallbackExceptionHelper):
 
         self.callback = _ffi.callback(
             "int (*)(SSL *, const unsigned char **, unsigned int *, void *)",
-            wrapper
+            wrapper,
         )
 
 
@@ -397,9 +403,9 @@ class _NpnSelectHelper(_CallbackExceptionHelper):
                 protolist = []
                 while instr:
                     length = indexbytes(instr, 0)
-                    proto = instr[1:length + 1]
+                    proto = instr[1 : length + 1]
                     protolist.append(proto)
-                    instr = instr[length + 1:]
+                    instr = instr[length + 1 :]
 
                 # Call the callback
                 outstr = callback(conn, protolist)
@@ -420,9 +426,11 @@ class _NpnSelectHelper(_CallbackExceptionHelper):
                 return 2  # SSL_TLSEXT_ERR_ALERT_FATAL
 
         self.callback = _ffi.callback(
-            ("int (*)(SSL *, unsigned char **, unsigned char *, "
-                "const unsigned char *, unsigned int, void *)"),
-            wrapper
+            (
+                "int (*)(SSL *, unsigned char **, unsigned char *, "
+                "const unsigned char *, unsigned int, void *)"
+            ),
+            wrapper,
         )
 
 
@@ -449,15 +457,15 @@ class _ALPNSelectHelper(_CallbackExceptionHelper):
                 protolist = []
                 while instr:
                     encoded_len = indexbytes(instr, 0)
-                    proto = instr[1:encoded_len + 1]
+                    proto = instr[1 : encoded_len + 1]
                     protolist.append(proto)
-                    instr = instr[encoded_len + 1:]
+                    instr = instr[encoded_len + 1 :]
 
                 # Call the callback
                 outbytes = callback(conn, protolist)
                 any_accepted = True
                 if outbytes is NO_OVERLAPPING_PROTOCOLS:
-                    outbytes = b''
+                    outbytes = b""
                     any_accepted = False
                 elif not isinstance(outbytes, bytes):
                     raise TypeError(
@@ -482,9 +490,11 @@ class _ALPNSelectHelper(_CallbackExceptionHelper):
                 return _lib.SSL_TLSEXT_ERR_ALERT_FATAL
 
         self.callback = _ffi.callback(
-            ("int (*)(SSL *, unsigned char **, unsigned char *, "
-                "const unsigned char *, unsigned int, void *)"),
-            wrapper
+            (
+                "int (*)(SSL *, unsigned char **, unsigned char *, "
+                "const unsigned char *, unsigned int, void *)"
+            ),
+            wrapper,
         )
 
 
@@ -596,7 +606,7 @@ class _OCSPClientCallbackHelper(_CallbackExceptionHelper):
                 ocsp_len = _lib.SSL_get_tlsext_status_ocsp_resp(ssl, ocsp_ptr)
                 if ocsp_len < 0:
                     # No OCSP data.
-                    ocsp_data = b''
+                    ocsp_data = b""
                 else:
                     # Copy the OCSP data, then pass it to the callback.
                     ocsp_data = _ffi.buffer(ocsp_ptr[0], ocsp_len)[:]
@@ -628,7 +638,8 @@ def _asFileDescriptor(obj):
         raise TypeError("argument must be an int, or have a fileno() method.")
     elif fd < 0:
         raise ValueError(
-            "file descriptor cannot be a negative integer (%i)" % (fd,))
+            "file descriptor cannot be a negative integer (%i)" % (fd,)
+        )
 
     return fd
 
@@ -643,8 +654,11 @@ def SSLeay_version(type):
 
 
 def _warn_npn():
-    warnings.warn("NPN is deprecated. Protocols should switch to using ALPN.",
-                  DeprecationWarning, stacklevel=3)
+    warnings.warn(
+        "NPN is deprecated. Protocols should switch to using ALPN.",
+        DeprecationWarning,
+        stacklevel=3,
+    )
 
 
 def _make_requires(flag, error):
@@ -657,11 +671,14 @@ def _make_requires(flag, error):
         ``Cryptography_HAS_NEXTPROTONEG``.
     :param error: The string to be used in the exception if the flag is false.
     """
+
     def _requires_decorator(func):
         if not flag:
+
             @wraps(func)
             def explode(*args, **kwargs):
                 raise NotImplementedError(error)
+
             return explode
         else:
             return func
@@ -687,6 +704,7 @@ class Session(object):
 
     .. versionadded:: 0.14
     """
+
     pass
 
 
@@ -698,6 +716,7 @@ class Context(object):
     :param method: One of SSLv2_METHOD, SSLv3_METHOD, SSLv23_METHOD, or
         TLSv1_METHOD.
     """
+
     _methods = {
         SSLv2_METHOD: "SSLv2_method",
         SSLv3_METHOD: "SSLv3_method",
@@ -709,7 +728,8 @@ class Context(object):
     _methods = dict(
         (identifier, getattr(_lib, name))
         for (identifier, name) in _methods.items()
-        if getattr(_lib, name, None) is not None)
+        if getattr(_lib, name, None) is not None
+    )
 
     def __init__(self, method):
         if not isinstance(method, integer_types):
@@ -790,8 +810,10 @@ class Context(object):
         @wraps(callback)
         def wrapper(size, verify, userdata):
             return callback(size, verify, self._passphrase_userdata)
+
         return _PassphraseHelper(
-            FILETYPE_PEM, wrapper, more_args=True, truncate=True)
+            FILETYPE_PEM, wrapper, more_args=True, truncate=True
+        )
 
     def set_passwd_cb(self, callback, userdata=None):
         """
@@ -818,7 +840,8 @@ class Context(object):
         self._passphrase_helper = self._wrap_callback(callback)
         self._passphrase_callback = self._passphrase_helper.callback
         _lib.SSL_CTX_set_default_passwd_cb(
-            self._context, self._passphrase_callback)
+            self._context, self._passphrase_callback
+        )
         self._passphrase_userdata = userdata
 
     def set_default_verify_paths(self):
@@ -848,9 +871,9 @@ class Context(object):
         # First we'll check to see if any env vars have been set. If so,
         # we won't try to do anything else because the user has set the path
         # themselves.
-        dir_env_var = _ffi.string(
-            _lib.X509_get_default_cert_dir_env()
-        ).decode("ascii")
+        dir_env_var = _ffi.string(_lib.X509_get_default_cert_dir_env()).decode(
+            "ascii"
+        )
         file_env_var = _ffi.string(
             _lib.X509_get_default_cert_file_env()
         ).decode("ascii")
@@ -861,13 +884,12 @@ class Context(object):
             # to the exact values we use in our manylinux1 builds. If they are
             # then we know to load the fallbacks
             if (
-                default_dir == _CRYPTOGRAPHY_MANYLINUX1_CA_DIR and
-                default_file == _CRYPTOGRAPHY_MANYLINUX1_CA_FILE
+                default_dir == _CRYPTOGRAPHY_MANYLINUX1_CA_DIR
+                and default_file == _CRYPTOGRAPHY_MANYLINUX1_CA_FILE
             ):
                 # This is manylinux1, let's load our fallback paths
                 self._fallback_default_verify_paths(
-                    _CERTIFICATE_FILE_LOCATIONS,
-                    _CERTIFICATE_PATH_LOCATIONS
+                    _CERTIFICATE_FILE_LOCATIONS, _CERTIFICATE_PATH_LOCATIONS
                 )
 
     def _check_env_vars_set(self, dir_env_var, file_env_var):
@@ -877,8 +899,8 @@ class Context(object):
         :return: bool
         """
         return (
-            os.environ.get(file_env_var) is not None or
-            os.environ.get(dir_env_var) is not None
+            os.environ.get(file_env_var) is not None
+            or os.environ.get(dir_env_var) is not None
         )
 
     def _fallback_default_verify_paths(self, file_path, dir_path):
@@ -996,7 +1018,8 @@ class Context(object):
             raise TypeError("filetype must be an integer")
 
         use_result = _lib.SSL_CTX_use_PrivateKey_file(
-            self._context, keyfile, filetype)
+            self._context, keyfile, filetype
+        )
         if not use_result:
             self._raise_passphrase_exception()
 
@@ -1052,11 +1075,8 @@ class Context(object):
         """
         buf = _text_to_bytes_and_warn("buf", buf)
         _openssl_assert(
-            _lib.SSL_CTX_set_session_id_context(
-                self._context,
-                buf,
-                len(buf),
-            ) == 1
+            _lib.SSL_CTX_set_session_id_context(self._context, buf, len(buf),)
+            == 1
         )
 
     def set_session_cache_mode(self, mode):
@@ -1202,19 +1222,17 @@ class Context(object):
         # invalid cipher string is passed, but without the following check
         # for the TLS 1.3 specific cipher suites it would never error.
         tmpconn = Connection(self, None)
-        if (
-            tmpconn.get_cipher_list() == [
-                'TLS_AES_256_GCM_SHA384',
-                'TLS_CHACHA20_POLY1305_SHA256',
-                'TLS_AES_128_GCM_SHA256'
-            ]
-        ):
+        if tmpconn.get_cipher_list() == [
+            "TLS_AES_256_GCM_SHA384",
+            "TLS_CHACHA20_POLY1305_SHA256",
+            "TLS_AES_128_GCM_SHA256",
+        ]:
             raise Error(
                 [
                     (
-                        'SSL routines',
-                        'SSL_CTX_set_cipher_list',
-                        'no cipher match',
+                        "SSL routines",
+                        "SSL_CTX_set_cipher_list",
+                        "no cipher match",
                     ),
                 ],
             )
@@ -1240,9 +1258,7 @@ class Context(object):
                 if not isinstance(ca_name, X509Name):
                     raise TypeError(
                         "client CAs must be X509Name objects, not %s "
-                        "objects" % (
-                            type(ca_name).__name__,
-                        )
+                        "objects" % (type(ca_name).__name__,)
                     )
                 copy = _lib.X509_NAME_dup(ca_name._name)
                 _openssl_assert(copy != _ffi.NULL)
@@ -1273,7 +1289,8 @@ class Context(object):
             raise TypeError("certificate_authority must be an X509 instance")
 
         add_result = _lib.SSL_CTX_add_client_CA(
-            self._context, certificate_authority._x509)
+            self._context, certificate_authority._x509
+        )
         _openssl_assert(add_result == 1)
 
     def set_timeout(self, timeout):
@@ -1311,11 +1328,14 @@ class Context(object):
             function call.
         :return: None
         """
+
         @wraps(callback)
         def wrapper(ssl, where, return_code):
             callback(Connection._reverse_mapping[ssl], where, return_code)
+
         self._info_callback = _ffi.callback(
-            "void (*)(const SSL *, int, int)", wrapper)
+            "void (*)(const SSL *, int, int)", wrapper
+        )
         _lib.SSL_CTX_set_info_callback(self._context, self._info_callback)
 
     def get_app_data(self):
@@ -1388,15 +1408,18 @@ class Context(object):
 
         .. versionadded:: 0.13
         """
+
         @wraps(callback)
         def wrapper(ssl, alert, arg):
             callback(Connection._reverse_mapping[ssl])
             return 0
 
         self._tlsext_servername_callback = _ffi.callback(
-            "int (*)(SSL *, int *, void *)", wrapper)
+            "int (*)(SSL *, int *, void *)", wrapper
+        )
         _lib.SSL_CTX_set_tlsext_servername_callback(
-            self._context, self._tlsext_servername_callback)
+            self._context, self._tlsext_servername_callback
+        )
 
     def set_tlsext_use_srtp(self, profiles):
         """
@@ -1431,7 +1454,8 @@ class Context(object):
         self._npn_advertise_helper = _NpnAdvertiseHelper(callback)
         self._npn_advertise_callback = self._npn_advertise_helper.callback
         _lib.SSL_CTX_set_next_protos_advertised_cb(
-            self._context, self._npn_advertise_callback, _ffi.NULL)
+            self._context, self._npn_advertise_callback, _ffi.NULL
+        )
 
     @_requires_npn
     def set_npn_select_callback(self, callback):
@@ -1450,7 +1474,8 @@ class Context(object):
         self._npn_select_helper = _NpnSelectHelper(callback)
         self._npn_select_callback = self._npn_select_helper.callback
         _lib.SSL_CTX_set_next_proto_select_cb(
-            self._context, self._npn_select_callback, _ffi.NULL)
+            self._context, self._npn_select_callback, _ffi.NULL
+        )
 
     @_requires_alpn
     def set_alpn_protos(self, protos):
@@ -1465,7 +1490,7 @@ class Context(object):
         """
         # Take the list of protocols and join them together, prefixing them
         # with their lengths.
-        protostr = b''.join(
+        protostr = b"".join(
             chain.from_iterable((int2byte(len(p)), p) for p in protos)
         )
 
@@ -1492,7 +1517,8 @@ class Context(object):
         self._alpn_select_helper = _ALPNSelectHelper(callback)
         self._alpn_select_callback = self._alpn_select_helper.callback
         _lib.SSL_CTX_set_alpn_select_cb(
-            self._context, self._alpn_select_callback, _ffi.NULL)
+            self._context, self._alpn_select_callback, _ffi.NULL
+        )
 
     def _set_ocsp_callback(self, helper, data):
         """
@@ -1556,6 +1582,7 @@ class Context(object):
 class Connection(object):
     """
     """
+
     _reverse_mapping = WeakValueDictionary()
 
     def __init__(self, context, socket=None):
@@ -1609,7 +1636,8 @@ class Connection(object):
             self._from_ssl = None
             self._socket = socket
             set_result = _lib.SSL_set_fd(
-                self._ssl, _asFileDescriptor(self._socket))
+                self._ssl, _asFileDescriptor(self._socket)
+            )
             _openssl_assert(set_result == 1)
 
     def __getattr__(self, name):
@@ -1618,9 +1646,10 @@ class Connection(object):
         on the Connection object.
         """
         if self._socket is None:
-            raise AttributeError("'%s' object has no attribute '%s'" % (
-                self.__class__.__name__, name
-            ))
+            raise AttributeError(
+                "'%s' object has no attribute '%s'"
+                % (self.__class__.__name__, name)
+            )
         else:
             return getattr(self._socket, name)
 
@@ -1777,9 +1806,7 @@ class Connection(object):
                 # SSL_write's num arg is an int,
                 # so we cannot send more than 2**31-1 bytes at once.
                 result = _lib.SSL_write(
-                    self._ssl,
-                    data + total_sent,
-                    min(left_to_send, 2147483647)
+                    self._ssl, data + total_sent, min(left_to_send, 2147483647)
                 )
                 self._raise_ssl_error(self._ssl, result)
                 total_sent += result
@@ -1803,6 +1830,7 @@ class Connection(object):
             result = _lib.SSL_read(self._ssl, buf, bufsiz)
         self._raise_ssl_error(self._ssl, result)
         return _ffi.buffer(buf, result)[:]
+
     read = recv
 
     def recv_into(self, buffer, nbytes=None, flags=None):
@@ -2069,7 +2097,8 @@ class Connection(object):
         :raise: NotImplementedError
         """
         raise NotImplementedError(
-            "Cannot make file object of OpenSSL.SSL.Connection")
+            "Cannot make file object of OpenSSL.SSL.Connection"
+        )
 
     def get_app_data(self):
         """
@@ -2182,10 +2211,16 @@ class Connection(object):
             context_buf = context
             context_len = len(context)
             use_context = 1
-        success = _lib.SSL_export_keying_material(self._ssl, outp, olen,
-                                                  label, len(label),
-                                                  context_buf, context_len,
-                                                  use_context)
+        success = _lib.SSL_export_keying_material(
+            self._ssl,
+            outp,
+            olen,
+            label,
+            len(label),
+            context_buf,
+            context_len,
+            use_context,
+        )
         _openssl_assert(success == 1)
         return _ffi.buffer(outp, olen)[:]
 
@@ -2470,7 +2505,7 @@ class Connection(object):
         """
         # Take the list of protocols and join them together, prefixing them
         # with their lengths.
-        protostr = b''.join(
+        protostr = b"".join(
             chain.from_iterable((int2byte(len(p)), p) for p in protos)
         )
 
@@ -2493,7 +2528,7 @@ class Connection(object):
         _lib.SSL_get0_alpn_selected(self._ssl, data, data_len)
 
         if not data_len:
-            return b''
+            return b""
 
         return _ffi.buffer(data[0], data_len[0])[:]