Generate range of possible subnets for an IP Address

README.md

Generate range of possible subnets for an IP Address

gensubnets.js

function ip2num(ip)
{
    var a = ip.split('.');
    return (+a[0] << 24) | (+a[1] << 16) | (+a[2] << 8) | +a[3];
}

function num2ip(n)
{
    return [((n >> 24) & 0xff), ((n >> 16) & 0xff), ((n >> 8) & 0xff), (n & 0xff)].join('.');
}

function genSubnets(ip, min, max)
{
    var ipn = ip2num(ip);
    min = min ? min : 8;
    max = max ? max : 32;

    var m = 0;
    for (var i = 0; i < min; i++)
        m = (m >> 1) | 0x80000000;

    var a = [];
    for (var i = min; i <= max; i++)
    {
        a[a.length] = num2ip(ipn & m) + '/' + i;
        m = (m >> 1) | 0x80000000;
    }

    return a;
}