Setup curl instance with values from ``self.config``.

def process_config(self, grab):
        """
        Setup curl instance with values from ``self.config``.
        """

        # Copy some config for future usage
        self.config_nobody = grab.config['nobody']
        self.config_body_maxsize = grab.config['body_maxsize']

        try:
            request_url = normalize_url(grab.config['url'])
        except Exception as ex:
            raise error.GrabInvalidUrl(
                u'%s: %s' % (six.text_type(ex), grab.config['url']))

        # py3 hack
        if not six.PY3:
            request_url = make_str(request_url)

        self.curl.setopt(pycurl.URL, request_url)

        # 30* redirects are handled by Grab
        self.curl.setopt(pycurl.FOLLOWLOCATION, 0)
        self.curl.setopt(pycurl.MAXREDIRS, grab.config['redirect_limit'])
        self.curl.setopt(pycurl.CONNECTTIMEOUT, grab.config['connect_timeout'])
        self.curl.setopt(pycurl.TIMEOUT, grab.config['timeout'])
        #self.curl.setopt(pycurl.IPRESOLVE, pycurl.IPRESOLVE_V4)
        # self.curl.setopt(pycurl.DNS_CACHE_TIMEOUT, 0)
        if not grab.config['connection_reuse']:
            self.curl.setopt(pycurl.FRESH_CONNECT, 1)
            self.curl.setopt(pycurl.FORBID_REUSE, 1)

        self.curl.setopt(pycurl.NOSIGNAL, 1)
        self.curl.setopt(pycurl.HEADERFUNCTION, self.header_processor)

        if grab.config['body_inmemory']:
            self.curl.setopt(pycurl.WRITEFUNCTION, self.body_processor)
        else:
            if not grab.config['body_storage_dir']:
                raise error.GrabMisuseError(
                    'Option body_storage_dir is not defined')
            self.setup_body_file(
                grab.config['body_storage_dir'],
                grab.config['body_storage_filename'],
                create_dir=grab.config['body_storage_create_dir'])
            self.curl.setopt(pycurl.WRITEFUNCTION, self.body_processor)

        if grab.config['verbose_logging']:
            self.verbose_logging = True

        # User-Agent
        if grab.config['user_agent'] is None:
            if grab.config['user_agent_file'] is not None:
                with open(grab.config['user_agent_file']) as inf:
                    lines = inf.read().splitlines()
                grab.config['user_agent'] = random.choice(lines)
            else:
                grab.config['user_agent'] = generate_user_agent()

        # If value is None then set empty string
        # None is not acceptable because in such case
        # pycurl will set its default user agent "PycURL/x.xx.x"
        if not grab.config['user_agent']:
            grab.config['user_agent'] = ''

        self.curl.setopt(pycurl.USERAGENT, grab.config['user_agent'])

        if grab.config['debug']:
            self.curl.setopt(pycurl.VERBOSE, 1)
            self.curl.setopt(pycurl.DEBUGFUNCTION, self.debug_processor)

        # Ignore SSL errors
        self.curl.setopt(pycurl.SSL_VERIFYPEER, 0)
        self.curl.setopt(pycurl.SSL_VERIFYHOST, 0)

        # Disabled to avoid SSL3_READ_BYTES:sslv3 alert handshake failure error
        # self.curl.setopt(pycurl.SSLVERSION, pycurl.SSLVERSION_SSLv3)

        if grab.request_method in ('POST', 'PUT'):
            if (grab.config['post'] is None
                    and grab.config['multipart_post'] is None):
                raise GrabMisuseError('Neither `post` or `multipart_post`'
                                      ' options was specified for the %s'
                                      ' request' % grab.request_method)

        if grab.request_method == 'POST':
            self.curl.setopt(pycurl.POST, 1)
            if grab.config['multipart_post']:
                if isinstance(grab.config['multipart_post'], six.string_types):
                    raise error.GrabMisuseError(
                        'multipart_post option could not be a string')
                post_items = normalize_http_values(
                    grab.config['multipart_post'],
                    charset=grab.config['charset'],
                    ignore_classes=(UploadFile, UploadContent),
                )
                # py3 hack
                #if six.PY3:
                #    post_items = decode_pairs(post_items,
                #                              grab.config['charset'])
                self.curl.setopt(pycurl.HTTPPOST,
                                 process_upload_items(post_items))
            elif grab.config['post']:
                post_data = normalize_post_data(grab.config['post'],
                                                grab.config['charset'])
                # py3 hack
                # if six.PY3:
                #    post_data = smart_unicode(post_data,
                #                              grab.config['charset'])
                self.curl.setopt(pycurl.POSTFIELDS, post_data)
            else:
                self.curl.setopt(pycurl.POSTFIELDS, '')
        elif grab.request_method == 'PUT':
            data = grab.config['post']
            if isinstance(data, six.text_type):
                # py3 hack
                # if six.PY3:
                #    data = data.encode('utf-8')
                # else:
                raise error.GrabMisuseError(
                    'Value of post option could be only '
                    'byte string if PUT method is used')
            self.curl.setopt(pycurl.UPLOAD, 1)
            self.curl.setopt(pycurl.CUSTOMREQUEST, 'PUT')
            self.curl.setopt(pycurl.READFUNCTION, StringIO(data).read)
            self.curl.setopt(pycurl.INFILESIZE, len(data))
        elif grab.request_method == 'PATCH':
            data = grab.config['post']
            if isinstance(data, six.text_type):
                raise error.GrabMisuseError(
                    'Value of post option could be only byte '
                    'string if PATCH method is used')
            self.curl.setopt(pycurl.UPLOAD, 1)
            self.curl.setopt(pycurl.CUSTOMREQUEST, 'PATCH')
            self.curl.setopt(pycurl.READFUNCTION, StringIO(data).read)
            self.curl.setopt(pycurl.INFILESIZE, len(data))
        elif grab.request_method == 'DELETE':
            self.curl.setopt(pycurl.CUSTOMREQUEST, 'DELETE')
        elif grab.request_method == 'HEAD':
            self.curl.setopt(pycurl.NOBODY, 1)
        elif grab.request_method == 'UPLOAD':
            self.curl.setopt(pycurl.UPLOAD, 1)
        elif grab.request_method == 'GET':
            self.curl.setopt(pycurl.HTTPGET, 1)
        elif grab.request_method == 'OPTIONS':
            data = grab.config['post']
            if data is not None:
                if isinstance(data, six.text_type):
                    raise error.GrabMisuseError(
                        'Value of post option could be only byte '
                        'string if PATCH method is used')
                self.curl.setopt(pycurl.UPLOAD, 1)
                self.curl.setopt(pycurl.READFUNCTION, StringIO(data).read)
                self.curl.setopt(pycurl.INFILESIZE, len(data))
            self.curl.setopt(pycurl.CUSTOMREQUEST, 'OPTIONS')
        else:
            raise error.GrabMisuseError('Invalid method: %s' %
                                        grab.request_method)

        headers = grab.config['common_headers'].copy()
        if grab.config['headers']:
            headers.update(grab.config['headers'])
        # This is required to avoid some problems
        headers.update({'Expect': ''})
        header_tuples = [str('%s: %s' % x) for x
                         in headers.items()]
        self.curl.setopt(pycurl.HTTPHEADER, header_tuples)

        self.process_cookie_options(grab, request_url)

        if grab.config['referer']:
            self.curl.setopt(pycurl.REFERER, str(grab.config['referer']))

        if grab.config['proxy']:
            self.curl.setopt(pycurl.PROXY, str(grab.config['proxy']))
        else:
            self.curl.setopt(pycurl.PROXY, '')

        if grab.config['proxy_userpwd']:
            self.curl.setopt(pycurl.PROXYUSERPWD,
                             str(grab.config['proxy_userpwd']))

        if grab.config['proxy_type']:
            key = 'PROXYTYPE_%s' % grab.config['proxy_type'].upper()
            self.curl.setopt(pycurl.PROXYTYPE, getattr(pycurl, key))

        if grab.config['encoding']:
            if ('gzip' in grab.config['encoding'] and
                    'zlib' not in pycurl.version):
                raise error.GrabMisuseError(
                    'You can not use gzip encoding because '
                    'pycurl was built without zlib support')
            self.curl.setopt(pycurl.ENCODING, grab.config['encoding'])

        if grab.config['userpwd']:
            self.curl.setopt(pycurl.USERPWD, str(grab.config['userpwd']))

        if grab.config.get('interface') is not None:
            self.curl.setopt(pycurl.INTERFACE, grab.config['interface'])

        if grab.config.get('reject_file_size') is not None:
            self.curl.setopt(pycurl.MAXFILESIZE,
                             grab.config['reject_file_size'])