fix: harden input handling and output safety (#79)

- canonical_url: sanitize via sanitizeUrl() (scheme allowlist) instead of
  bare trim() — closes stored-XSS via addHeadLink() on the public frontend
- AI endpoint: replace die('Invalid Token') with a clean event result,
  and strip_tags + truncate article_title to 200 chars before use
- SitemapBuilder: whitelist changefreq against the sitemap spec enum,
  intval() noindex IDs, strict in_array comparison
- MokoOG: log a WARNING when sitemap.xml write fails instead of ignoring it

source/packages/plg_content_mokoog/src/Extension/MokoOGContent.php

@@ -274,7 +274,7 @@ final class MokoOGContent extends CMSPlugin implements SubscriberInterface
             'seo_title'        => strip_tags(trim($ogData['seo_title'] ?? '')),
             'meta_description' => strip_tags(trim($ogData['meta_description'] ?? '')),
             'robots'           => trim($robots),
-            'canonical_url'    => trim($ogData['canonical_url'] ?? ''),
+            'canonical_url'    => $this->sanitizeUrl($ogData['canonical_url'] ?? ''),
             'published'        => 1,
             'modified'         => Factory::getDate()->toSql(),
         ];

source/packages/plg_system_mokoog/src/Extension/MokoOG.php

@@ -832,7 +832,10 @@ final class MokoOG extends CMSPlugin implements SubscriberInterface
 
         $changefreq = $this->params->get('sitemap_changefreq', 'weekly');
         $xml = SitemapBuilder::generate($changefreq);
-        SitemapBuilder::writeToFile($xml);
+
+        if (!SitemapBuilder::writeToFile($xml)) {
+            \Joomla\CMS\Log\Log::add('MokoOG: Failed to write sitemap.xml — check file permissions', \Joomla\CMS\Log\Log::WARNING, 'mokoog');
+        }
     }
 
     /**
@@ -850,7 +853,10 @@ final class MokoOG extends CMSPlugin implements SubscriberInterface
             return;
         }
 
-        \Joomla\CMS\Session\Session::checkToken() or die('Invalid Token');
+        if (!\Joomla\CMS\Session\Session::checkToken()) {
+            $event->setArgument('result', ['Invalid Token']);
+            return;
+        }
 
         if (!$this->params->get('ai_enabled', 0)) {
             $event->setArgument('result', ['AI generation is not enabled']);
@@ -868,7 +874,7 @@ final class MokoOG extends CMSPlugin implements SubscriberInterface
 
         $input        = $app->getInput();
         $field        = $input->getString('field', 'title');
-        $articleTitle = $input->getString('article_title', '');
+        $articleTitle = mb_substr(strip_tags($input->getString('article_title', '')), 0, 200);
 
         $prompt = $field === 'title'
             ? "Generate a concise, engaging social media sharing title (max 60 characters) for an article titled: \"$articleTitle\". Return only the title text, no quotes or explanation."

source/packages/plg_system_mokoog/src/Helper/SitemapBuilder.php

@@ -32,6 +32,9 @@ class SitemapBuilder
      */
     public static function generate(string $changefreq = 'weekly'): string
     {
+        $allowed = ['always', 'hourly', 'daily', 'weekly', 'monthly', 'yearly', 'never'];
+        $changefreq = \in_array($changefreq, $allowed, true) ? $changefreq : 'weekly';
+
         $db = Factory::getDbo();
 
         // Get all published articles
@@ -51,7 +54,7 @@ class SitemapBuilder
             ->where($db->quoteName('robots') . ' LIKE ' . $db->quote('%noindex%'));
 
         $db->setQuery($noindexQuery);
-        $noindexIds = $db->loadColumn();
+        $noindexIds = array_map('intval', $db->loadColumn());
 
         $root = rtrim(Uri::root(), '/');
         $xml  = '<?xml version="1.0" encoding="UTF-8"?>' . "\n";
@@ -66,7 +69,7 @@ class SitemapBuilder
 
         foreach ($articles as $article) {
             // Skip noindexed
-            if (in_array((int) $article->id, $noindexIds)) {
+            if (\in_array((int) $article->id, $noindexIds, true)) {
                 continue;
             }