'Tests an URL for shell shock vulnerabilities.
:param freq: A FuzzableRequest'

def audit(self, freq, orig_response):

    url = freq.get_url()
    if (url not in self.already_tested_urls):
        self.already_tested_urls.add(url)
        for detection_method in [self._with_header_echo_injection, self._with_time_delay]:
            if detection_method(freq):
                break
