add persist_user_denylist and persist_user_allowlist

Closes: #3511

src/utils/is_requester_allowed_to_persist.hpp

@@ -0,0 +1,55 @@
+#pragma once
+
+#include "xmpp/jid.hpp"
+#include <config/config.hpp>
+
+namespace utils
+{
+/**
+ * Check config if a given requester is allowed to persist target
+ *
+ * The following values are checked
+ *
+ * - A user's jid (foo@example.com)
+ * - A user's domain (example.com)
+ *
+ * The following config options are checked in order
+ *
+ * 1. `persist_user_denylist` contains the requester's jid
+ * 2. `persist_user_allowlist` contains the requester's jid
+ * 3. `persist_user_denylist` contains the requester's domain
+ * 4. `persist_user_allowlist` contains the contains the requester's domain
+ * 5. allow
+ */
+inline bool is_requester_allowed_to_persist(const Jid &requester) {
+  // requester.bare checks
+  // deny
+  // 1.
+  bool jid_in_user_denylist = Config::is_in_list("persist_user_denylist", requester.bare());
+  if (jid_in_user_denylist)
+    return false;
+
+  // allow
+  // 2.
+  bool jid_in_user_allowlist = Config::is_in_list("persist_user_allowlist", requester.bare());
+  if (jid_in_user_allowlist)
+    return true;
+
+  // requester.domain checks
+  // deny
+  // 3.
+  bool domain_in_user_denylist = Config::is_in_list("persist_user_denylist", requester.domain);
+  if (domain_in_user_denylist)
+    return false;
+
+  // allow
+  // 4.
+  bool domain_in_user_allowlist = Config::is_in_list("persist_user_allowlist", requester.domain);
+  if (domain_in_user_allowlist)
+    return true;
+
+  // default allow
+  // 5.
+  return true;
+}
+}