Fix policy_callback mutex access

Author: fchevassu-antidot

src/webserver.cpp

@@ -411,10 +411,10 @@ MHD_Result policy_callback(void *cls, const struct sockaddr* addr, socklen_t add
 
     if (!ws->ban_system_enabled) return MHD_YES;
 
-    std::shared_lock bans_lock(bans_mutex);
-    std::shared_lock allowances_lock(allowances_mutex);
-    const bool is_banned = (static_cast<webserver *>(cls))->bans.count(ip_representation(addr));
-    const bool is_allowed = (static_cast<webserver *>(cls))->allowances.count(ip_representation(addr));
+    std::shared_lock bans_lock(ws->bans_mutex);
+    std::shared_lock allowances_lock(ws->allowances_mutex);
+    const bool is_banned = ws->bans.count(ip_representation(addr));
+    const bool is_allowed = ws->allowances.count(ip_representation(addr));
 
     if ((ws->default_policy == http_utils::ACCEPT && is_banned && !is_allowed) ||
         (ws->default_policy == http_utils::REJECT && !is_banned && is_allowed))