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Diffstat (limited to 'python/urllib3/contrib/_securetransport/low_level.py')
| -rw-r--r-- | python/urllib3/contrib/_securetransport/low_level.py | 346 |
1 files changed, 0 insertions, 346 deletions
diff --git a/python/urllib3/contrib/_securetransport/low_level.py b/python/urllib3/contrib/_securetransport/low_level.py deleted file mode 100644 index b13cd9e..0000000 --- a/python/urllib3/contrib/_securetransport/low_level.py +++ /dev/null @@ -1,346 +0,0 @@ -""" -Low-level helpers for the SecureTransport bindings. - -These are Python functions that are not directly related to the high-level APIs -but are necessary to get them to work. They include a whole bunch of low-level -CoreFoundation messing about and memory management. The concerns in this module -are almost entirely about trying to avoid memory leaks and providing -appropriate and useful assistance to the higher-level code. -""" -import base64 -import ctypes -import itertools -import re -import os -import ssl -import tempfile - -from .bindings import Security, CoreFoundation, CFConst - - -# This regular expression is used to grab PEM data out of a PEM bundle. -_PEM_CERTS_RE = re.compile( - b"-----BEGIN CERTIFICATE-----\n(.*?)\n-----END CERTIFICATE-----", re.DOTALL -) - - -def _cf_data_from_bytes(bytestring): - """ - Given a bytestring, create a CFData object from it. This CFData object must - be CFReleased by the caller. - """ - return CoreFoundation.CFDataCreate( - CoreFoundation.kCFAllocatorDefault, bytestring, len(bytestring) - ) - - -def _cf_dictionary_from_tuples(tuples): - """ - Given a list of Python tuples, create an associated CFDictionary. - """ - dictionary_size = len(tuples) - - # We need to get the dictionary keys and values out in the same order. - keys = (t[0] for t in tuples) - values = (t[1] for t in tuples) - cf_keys = (CoreFoundation.CFTypeRef * dictionary_size)(*keys) - cf_values = (CoreFoundation.CFTypeRef * dictionary_size)(*values) - - return CoreFoundation.CFDictionaryCreate( - CoreFoundation.kCFAllocatorDefault, - cf_keys, - cf_values, - dictionary_size, - CoreFoundation.kCFTypeDictionaryKeyCallBacks, - CoreFoundation.kCFTypeDictionaryValueCallBacks, - ) - - -def _cf_string_to_unicode(value): - """ - Creates a Unicode string from a CFString object. Used entirely for error - reporting. - - Yes, it annoys me quite a lot that this function is this complex. - """ - value_as_void_p = ctypes.cast(value, ctypes.POINTER(ctypes.c_void_p)) - - string = CoreFoundation.CFStringGetCStringPtr( - value_as_void_p, - CFConst.kCFStringEncodingUTF8 - ) - if string is None: - buffer = ctypes.create_string_buffer(1024) - result = CoreFoundation.CFStringGetCString( - value_as_void_p, - buffer, - 1024, - CFConst.kCFStringEncodingUTF8 - ) - if not result: - raise OSError('Error copying C string from CFStringRef') - string = buffer.value - if string is not None: - string = string.decode('utf-8') - return string - - -def _assert_no_error(error, exception_class=None): - """ - Checks the return code and throws an exception if there is an error to - report - """ - if error == 0: - return - - cf_error_string = Security.SecCopyErrorMessageString(error, None) - output = _cf_string_to_unicode(cf_error_string) - CoreFoundation.CFRelease(cf_error_string) - - if output is None or output == u'': - output = u'OSStatus %s' % error - - if exception_class is None: - exception_class = ssl.SSLError - - raise exception_class(output) - - -def _cert_array_from_pem(pem_bundle): - """ - Given a bundle of certs in PEM format, turns them into a CFArray of certs - that can be used to validate a cert chain. - """ - # Normalize the PEM bundle's line endings. - pem_bundle = pem_bundle.replace(b"\r\n", b"\n") - - der_certs = [ - base64.b64decode(match.group(1)) - for match in _PEM_CERTS_RE.finditer(pem_bundle) - ] - if not der_certs: - raise ssl.SSLError("No root certificates specified") - - cert_array = CoreFoundation.CFArrayCreateMutable( - CoreFoundation.kCFAllocatorDefault, - 0, - ctypes.byref(CoreFoundation.kCFTypeArrayCallBacks) - ) - if not cert_array: - raise ssl.SSLError("Unable to allocate memory!") - - try: - for der_bytes in der_certs: - certdata = _cf_data_from_bytes(der_bytes) - if not certdata: - raise ssl.SSLError("Unable to allocate memory!") - cert = Security.SecCertificateCreateWithData( - CoreFoundation.kCFAllocatorDefault, certdata - ) - CoreFoundation.CFRelease(certdata) - if not cert: - raise ssl.SSLError("Unable to build cert object!") - - CoreFoundation.CFArrayAppendValue(cert_array, cert) - CoreFoundation.CFRelease(cert) - except Exception: - # We need to free the array before the exception bubbles further. - # We only want to do that if an error occurs: otherwise, the caller - # should free. - CoreFoundation.CFRelease(cert_array) - - return cert_array - - -def _is_cert(item): - """ - Returns True if a given CFTypeRef is a certificate. - """ - expected = Security.SecCertificateGetTypeID() - return CoreFoundation.CFGetTypeID(item) == expected - - -def _is_identity(item): - """ - Returns True if a given CFTypeRef is an identity. - """ - expected = Security.SecIdentityGetTypeID() - return CoreFoundation.CFGetTypeID(item) == expected - - -def _temporary_keychain(): - """ - This function creates a temporary Mac keychain that we can use to work with - credentials. This keychain uses a one-time password and a temporary file to - store the data. We expect to have one keychain per socket. The returned - SecKeychainRef must be freed by the caller, including calling - SecKeychainDelete. - - Returns a tuple of the SecKeychainRef and the path to the temporary - directory that contains it. - """ - # Unfortunately, SecKeychainCreate requires a path to a keychain. This - # means we cannot use mkstemp to use a generic temporary file. Instead, - # we're going to create a temporary directory and a filename to use there. - # This filename will be 8 random bytes expanded into base64. We also need - # some random bytes to password-protect the keychain we're creating, so we - # ask for 40 random bytes. - random_bytes = os.urandom(40) - filename = base64.b16encode(random_bytes[:8]).decode('utf-8') - password = base64.b16encode(random_bytes[8:]) # Must be valid UTF-8 - tempdirectory = tempfile.mkdtemp() - - keychain_path = os.path.join(tempdirectory, filename).encode('utf-8') - - # We now want to create the keychain itself. - keychain = Security.SecKeychainRef() - status = Security.SecKeychainCreate( - keychain_path, - len(password), - password, - False, - None, - ctypes.byref(keychain) - ) - _assert_no_error(status) - - # Having created the keychain, we want to pass it off to the caller. - return keychain, tempdirectory - - -def _load_items_from_file(keychain, path): - """ - Given a single file, loads all the trust objects from it into arrays and - the keychain. - Returns a tuple of lists: the first list is a list of identities, the - second a list of certs. - """ - certificates = [] - identities = [] - result_array = None - - with open(path, 'rb') as f: - raw_filedata = f.read() - - try: - filedata = CoreFoundation.CFDataCreate( - CoreFoundation.kCFAllocatorDefault, - raw_filedata, - len(raw_filedata) - ) - result_array = CoreFoundation.CFArrayRef() - result = Security.SecItemImport( - filedata, # cert data - None, # Filename, leaving it out for now - None, # What the type of the file is, we don't care - None, # what's in the file, we don't care - 0, # import flags - None, # key params, can include passphrase in the future - keychain, # The keychain to insert into - ctypes.byref(result_array) # Results - ) - _assert_no_error(result) - - # A CFArray is not very useful to us as an intermediary - # representation, so we are going to extract the objects we want - # and then free the array. We don't need to keep hold of keys: the - # keychain already has them! - result_count = CoreFoundation.CFArrayGetCount(result_array) - for index in range(result_count): - item = CoreFoundation.CFArrayGetValueAtIndex( - result_array, index - ) - item = ctypes.cast(item, CoreFoundation.CFTypeRef) - - if _is_cert(item): - CoreFoundation.CFRetain(item) - certificates.append(item) - elif _is_identity(item): - CoreFoundation.CFRetain(item) - identities.append(item) - finally: - if result_array: - CoreFoundation.CFRelease(result_array) - - CoreFoundation.CFRelease(filedata) - - return (identities, certificates) - - -def _load_client_cert_chain(keychain, *paths): - """ - Load certificates and maybe keys from a number of files. Has the end goal - of returning a CFArray containing one SecIdentityRef, and then zero or more - SecCertificateRef objects, suitable for use as a client certificate trust - chain. - """ - # Ok, the strategy. - # - # This relies on knowing that macOS will not give you a SecIdentityRef - # unless you have imported a key into a keychain. This is a somewhat - # artificial limitation of macOS (for example, it doesn't necessarily - # affect iOS), but there is nothing inside Security.framework that lets you - # get a SecIdentityRef without having a key in a keychain. - # - # So the policy here is we take all the files and iterate them in order. - # Each one will use SecItemImport to have one or more objects loaded from - # it. We will also point at a keychain that macOS can use to work with the - # private key. - # - # Once we have all the objects, we'll check what we actually have. If we - # already have a SecIdentityRef in hand, fab: we'll use that. Otherwise, - # we'll take the first certificate (which we assume to be our leaf) and - # ask the keychain to give us a SecIdentityRef with that cert's associated - # key. - # - # We'll then return a CFArray containing the trust chain: one - # SecIdentityRef and then zero-or-more SecCertificateRef objects. The - # responsibility for freeing this CFArray will be with the caller. This - # CFArray must remain alive for the entire connection, so in practice it - # will be stored with a single SSLSocket, along with the reference to the - # keychain. - certificates = [] - identities = [] - - # Filter out bad paths. - paths = (path for path in paths if path) - - try: - for file_path in paths: - new_identities, new_certs = _load_items_from_file( - keychain, file_path - ) - identities.extend(new_identities) - certificates.extend(new_certs) - - # Ok, we have everything. The question is: do we have an identity? If - # not, we want to grab one from the first cert we have. - if not identities: - new_identity = Security.SecIdentityRef() - status = Security.SecIdentityCreateWithCertificate( - keychain, - certificates[0], - ctypes.byref(new_identity) - ) - _assert_no_error(status) - identities.append(new_identity) - - # We now want to release the original certificate, as we no longer - # need it. - CoreFoundation.CFRelease(certificates.pop(0)) - - # We now need to build a new CFArray that holds the trust chain. - trust_chain = CoreFoundation.CFArrayCreateMutable( - CoreFoundation.kCFAllocatorDefault, - 0, - ctypes.byref(CoreFoundation.kCFTypeArrayCallBacks), - ) - for item in itertools.chain(identities, certificates): - # ArrayAppendValue does a CFRetain on the item. That's fine, - # because the finally block will release our other refs to them. - CoreFoundation.CFArrayAppendValue(trust_chain, item) - - return trust_chain - finally: - for obj in itertools.chain(identities, certificates): - CoreFoundation.CFRelease(obj) |