[BUGFIX] Use scheme://host:port of current request resolving error page

Error pages in site configurations don't need to point to an absolute URI.
When such error pages get resolved, the scheme, host and port of the
request get attached to the resolved page.

Resolves: #86935
Releases: master, 9.5
Change-Id: I1b29b7e7ec51c67e6630ed0f2de5f7e3276e8e7d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60873
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>

typo3/sysext/core/Classes/Error/PageErrorHandler/PageContentErrorHandler.php

@@ -72,6 +72,7 @@ public function handlePageError(ServerRequestInterface $request, string $message
             $resolvedUrl = $this->resolveUrl($request, $this->errorHandlerConfiguration['errorContentSource']);
             $content = null;
             $report = [];
+
             if ($resolvedUrl !== (string)$request->getUri()) {
                 $content = GeneralUtility::getUrl($resolvedUrl, 0, null, $report);
                 if ($content === false && ((int)$report['error'] === -1 || (int)$report['error'] > 200)) {
@@ -112,10 +113,28 @@ protected function resolveUrl(ServerRequestInterface $request, string $typoLinkU
         if (!$language instanceof SiteLanguage || !$language->isEnabled()) {
             $language = $site->getDefaultLanguage();
         }
+
         // Build Url
-        return (string)$site->getRouter()->generateUri(
+        $uri = $site->getRouter()->generateUri(
             (int)$urlParams['pageuid'],
             ['_language' => $language]
         );
+
+        // Fallback to the current URL if the site is not having a proper scheme and host
+        $currentUri = $request->getUri();
+        if (empty($uri->getScheme())) {
+            $uri = $uri->withScheme($currentUri->getScheme());
+        }
+        if (empty($uri->getUserInfo())) {
+            $uri = $uri->withUserInfo($currentUri->getUserInfo());
+        }
+        if (empty($uri->getHost())) {
+            $uri = $uri->withHost($currentUri->getHost());
+        }
+        if ($uri->getPort() === null) {
+            $uri = $uri->withPort($currentUri->getPort());
+        }
+
+        return (string)$uri;
     }
 }