Method from_bytes

pager_lib/smb/security_descriptors.py:233–278

(cls, data)

    @classmethod
    def from_bytes(cls, data):
        header_size = struct.calcsize(cls.HEADER_FORMAT)
        header = data[:header_size]
        type_, flags, size = struct.unpack(cls.HEADER_FORMAT, header)

        assert len(data) >= size

        body = data[header_size:size]
        additional_data = {}

        # In all ACE types, the mask immediately follows the header.
        mask = struct.unpack('<I', body[:4])[0]
        body = body[4:]

        # All OBJECT-type ACEs contain additional flags, and two GUIDs as
        # the following fields.
        if type_ in (ACE_TYPE_ACCESS_ALLOWED_OBJECT,
                     ACE_TYPE_ACCESS_DENIED_OBJECT,
                     ACE_TYPE_ACCESS_ALLOWED_CALLBACK_OBJECT,
                     ACE_TYPE_ACCESS_DENIED_CALLBACK_OBJECT,
                     ACE_TYPE_SYSTEM_AUDIT_OBJECT,
                     ACE_TYPE_SYSTEM_AUDIT_CALLBACK_OBJECT):
            additional_data['flags'] = struct.unpack('<I', body[:4])[0]
            additional_data['object_type'] = body[4:20]
            additional_data['inherited_object_type'] = body[20:36]
            body = body[36:]

        # Then the SID in all types.
        sid, body = SID.from_bytes(body, return_tail=True)

        # CALLBACK-type ACEs (and for some obscure reason,
        # SYSTEM_AUDIT_OBJECT) have a final tail of application data.
        if type_ in (ACE_TYPE_ACCESS_ALLOWED_CALLBACK,
                     ACE_TYPE_ACCESS_DENIED_CALLBACK,
                     ACE_TYPE_ACCESS_ALLOWED_CALLBACK_OBJECT,
                     ACE_TYPE_ACCESS_DENIED_CALLBACK_OBJECT,
                     ACE_TYPE_SYSTEM_AUDIT_OBJECT,
                     ACE_TYPE_SYSTEM_AUDIT_CALLBACK,
                     ACE_TYPE_SYSTEM_AUDIT_CALLBACK_OBJECT):
            additional_data['application_data'] = body

        # SYSTEM_RESOURCE_ATTRIBUTE ACEs have a tail of attribute data.
        if type_ == ACE_TYPE_SYSTEM_RESOURCE_ATTRIBUTE:
            additional_data['attribute_data'] = body

        return cls(type_, flags, mask, sid, additional_data)


class ACL(object):