const maxProtoLength = len("RSVP-E2E-IGNORE") + 10 // with room to grow

func lookupProtocolMap(name string) (int, error) {
	var lowerProtocol [maxProtoLength]byte
	n := copy(lowerProtocol[:], name)
	lowerASCIIBytes(lowerProtocol[:n])
	proto, found := protocols[string(lowerProtocol[:n])]
	if !found || n != len(name) {
		return 0, &AddrError{Err: "unknown IP protocol specified", Addr: name}
	}
	return proto, nil
}