helpers\View: Ensure makeBaseUrl returns absolute URI

This is required by both uses:

- RSS controller: RSS feeds are supposed to contain absolute paths
- Session: Cookies depend on URI scheme and host

If `base_url` was configured to an absolute path reference, not an absolute URI,
those would fail.

Author: jtojnar

src/helpers/View.php

@@ -34,9 +34,13 @@ public function __construct(Configuration $configuration) {
     }
 
     /**
-     * Returns the base url of the page. If a base url was configured in the
-     * config.ini this will be used. Otherwise base url will be generated by
-     * globale server variables ($_SERVER).
+     * Returns the absolute base URL of the page, with path ending with a /.
+     *
+     * The returned value depends on the value of the `base_url` option in `config.ini`:
+     *
+     * - unset – implicit base URI automatically determined from global server variables ($_SERVER)
+     * - absolute path – the implicit base URI with path replaced with the configured value
+     * - absolute URL – the configured value as is
      */
     public function getBaseUrl(): Uri {
         if ($this->baseUrl === null) {
@@ -49,7 +53,7 @@ public function getBaseUrl(): Uri {
     private function makeBaseUrl(): Uri {
         $base = $this->configuration->baseUrl;
 
-        if ($base !== null) {
+        if ($base !== null && Uri::isAbsolute($base)) {
             // base url in config.ini file
             return $base;
         }
@@ -87,7 +91,8 @@ private function makeBaseUrl(): Uri {
             $port = ':' . $_SERVER['HTTP_X_FORWARDED_PORT'];
         }
 
-        $base = new Uri($protocol . '://' . $host . $port . $subdir . '/');
+        $base = (new Uri($protocol . '://' . $host . $port))
+            ->withPath($base !== null ? $base->getPath() : ($subdir . '/'));
 
         return $base;
     }