function drupal_generate_test_ua

Generates a user agent string with a HMAC and timestamp for tests.

Return value

string|null The user agent, or NULL on failure.

File

core/includes/bootstrap.inc, line 225

Code

function drupal_generate_test_ua($prefix) {
    static $key, $last_prefix;
    if (!isset($key) || $last_prefix != $prefix) {
        $last_prefix = $prefix;
        $test_db = new TestDatabase($prefix);
        $key_file = DRUPAL_ROOT . '/' . $test_db->getTestSitePath() . '/.htkey';
        // When issuing an outbound HTTP client request from within an inbound test
        // request, then the outbound request has to use the same User-Agent header
        // as the inbound request. A newly generated private key for the same test
        // prefix would invalidate all subsequent inbound requests.
        // @see \Drupal\Core\Test\HttpClientMiddleware\TestHttpClientMiddleware
        if (DRUPAL_TEST_IN_CHILD_SITE && ($parent_prefix = drupal_valid_test_ua())) {
            if ($parent_prefix != $prefix) {
                throw new \RuntimeException("Malformed User-Agent: Expected '{$parent_prefix}' but got '{$prefix}'.");
            }
            // If the file is not readable, a PHP warning is expected in this case.
            $private_key = file_get_contents($key_file);
        }
        else {
            // Generate and save a new hash salt for a test run.
            // Consumed by drupal_valid_test_ua() before settings.php is loaded.
            $private_key = Crypt::randomBytesBase64(55);
            if (!@file_put_contents($key_file, $private_key)) {
                return NULL;
            }
        }
        // The file properties add more entropy not easily accessible to others.
        $key = $private_key . filectime(__FILE__) . fileinode(__FILE__);
    }
    // Generate a moderately secure HMAC based on the database credentials.
    $salt = uniqid('', TRUE);
    $check_string = $prefix . ':' . time() . ':' . $salt;
    return 'simple' . $check_string . ':' . Crypt::hmacBase64($check_string, $key);
}