infinite redirect under certain circumstances

[fritzmg]

This code

// Redirect to the website root or language root (e.g. en/)
if (\Environment::get('relativeRequest') == '')
{
    if (\Config::get('addLanguageToUrl') && !\Config::get('doNotRedirectEmpty'))
    {
        $arrParams = array('_locale' => $objRootPage->language);

        $strUrl = \System::getContainer()->get('router')->generate('contao_index', $arrParams);
        $strUrl = substr($strUrl, strlen(\Environment::get('path')) + 1);

        static::redirect($strUrl, 301);
    }
    elseif (($objPage = \PageModel::findFirstPublishedByPid($objRootPage->id)) !== null)
    {
        // Redirect if the page is not the language fall back or the alias is not "index" or "/" (see #8498 and #8560)
        if (!$objRootPage->fallback || !in_array($objPage->alias, array('index', '/')))
        {
            static::redirect($objPage->getFrontendUrl(), 302);
        }
    }
}

from Frontend.php#L343-L363 causes an infinite redirect under the following setup for example:

Reproduction

1. Create the following website structure:
   • Set a page layout for each website root.
   • The English website root has the language en set and is not the fallback.
   • The German website root has the language de set and it is the fallback.
   • The English Home page has the Alias index, the German Home page has the Alias home.
2. Set contao.prepend_locale to false.
3. Set the primary language of your browser to en.

Open the website (without a request parameter) in the frontend. Contao will redirect you infinite times.

Cause

Since addLanguageToUrl is false, we will arrive at this bit of code:

elseif (($objPage = \PageModel::findFirstPublishedByPid($objRootPage->id)) !== null)
{
    // Redirect if the page is not the language fall back or the alias is not "index" or "/" (see #8498 and #8560)
    if (!$objRootPage->fallback || !in_array($objPage->alias, array('index', '/')))
    {
        static::redirect($objPage->getFrontendUrl(), 302);
    }
}

Since the Accept-Language is en the root page found from

$objRootPage = \PageModel::findFirstPublishedRootByHostAndLanguage($host, $accept_language);

will be the english one and the first published page within that website root is the English Home page with the alias index. However, since that website root is not defined as the fallback language, Contao will redirect to the first published page within the website root. And since that page has the alias index, the redirect will be an empty request and the whole thing starts over again.

[leofeyer]

Fixed in 8bdd923.