CheckRelayIP reports whether an IP relayed from the given sender IP is a valid connection target.

IsLAN reports whether an IP is a local network address.

IsSpecialNetwork reports whether an IP is located in a special-use network range This includes broadcast, multicast and documentation addresses.

IsTemporaryError checks whether the given error should be considered temporary.

ParseNetlist parses a comma-separated list of CIDR masks.

Netlist is a list of IP networks.