Function gateway_admin_token_path 

pub fn gateway_admin_token_path(data_dir: &Path) -> PathBuf

Where a gateway whose data directory is data_dir keeps its admin secret.

The secret is what proves a caller is local. A loopback TCP peer is not proof: a reverse proxy or tunnel on the same host relays remote callers from loopback too, with or without forwarding headers. Reading this owner-only file requires running as the gateway’s user on its host.