Function is_non_global_v4 

pub fn is_non_global_v4(v4: Ipv4Addr) -> bool

True when an IPv4 address is not globally routable (loopback, RFC 1918, link-local, CGNAT, documentation, benchmarking, reserved, multicast).

The classification follows the IANA IPv4 Special-Purpose Address Registry. Deprecated translation space is rejected conservatively even where the registry no longer assigns a global-reachability value.