Merge pull request #6002 from christianbeeznest/ofaj-22284

Message: Convert relative links to absolute in email content - refs BT#22284

public/main/inc/lib/message.lib.php

@@ -352,6 +352,8 @@ class MessageManager
             if ($sendEmail) {
                 $notification = new Notification();
                 $sender_info = api_get_user_info($user_sender_id);
+                $baseUrl = $baseUrl ?? api_get_path(WEB_PATH);
+                $content = self::processRelativeLinks($content, $baseUrl);
 
                 // add file attachment additional attributes
                 $attachmentAddedByMail = [];
@@ -422,6 +424,20 @@ class MessageManager
         return false;
     }
 
+    /**
+     * Converts relative URLs in href and src attributes to absolute URLs.
+     */
+    private static function processRelativeLinks(string $content, string $baseUrl): string
+    {
+        return preg_replace_callback(
+            '/(href|src)="(\/[^"]*)"/',
+            function ($matches) use ($baseUrl) {
+                return $matches[1] . '="' . rtrim($baseUrl, '/') . $matches[2] . '"';
+            },
+            $content
+        );
+    }
+
     /**
      * @param int    $receiverUserId
      * @param string $subject