trifid_mobile/lib/models/CIDR.dart

class CIDR {
  CIDR({this.ip = '', this.bits = 0});

  String ip;
  int bits;

  @override
  String toString() {
    return '$ip/$bits';
  }

  String toJson() {
    return toString();
  }

  factory CIDR.fromString(String val) {
    final parts = val.split('/');
    if (parts.length != 2) {
      throw 'Invalid CIDR string';
    }

    return CIDR(
      ip: parts[0],
      bits: int.parse(parts[1]),
    );
  }
}