get Cider Base IP - Java Network

Java examples for Network:IP Address

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Description

get Cider Base IP

Demo Code


import java.util.ArrayList;
import java.util.regex.Pattern;

public class Main{
    public static void main(String[] argv) throws Exception{
        long ip = 2;
        int cidr = 2;
        System.out.println(getCiderBaseIP(ip,cidr));
    }/*w ww  . jav a  2  s .  com*/
    public static long getCiderBaseIP(final long ip, final int cidr)
            throws InvalidIPAddressException {

        long netmask = getSubnetMaskNumeric(cidr);

        // get base network ip for this ip/netmask combo
        long baseIP = ip & netmask;
        return baseIP;
    }
    public static long getSubnetMaskNumeric(final int cidr)
            throws InvalidIPAddressException {

        if (cidr > 32 || cidr < 0)
            throw new InvalidIPAddressException(
                    "CIDR can not be greater than 32");

        // starting /24 netmask, in decimal (255.255.255.0)
        long netmask = 4294967040L;

        // calculating and correcting netmask
        if (cidr > 24) {
            for (long i = cidr; i > 24; i--) {
                netmask += (long) (java.lang.Math.pow(2, (32 - i)));
            }
        } else if (cidr < 24) {
            for (long i = cidr; i < 24; i++) {
                netmask -= (long) (java.lang.Math.pow(2, (32 - (i + 1))));
            }
        }

        return netmask;
    }
}

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