I’m trying to determine if a gateway address in with the same subnet as another IP Address.

The code I’m using is :

var ip2long = function( ip ){
    var components;

    if ( components = ip.match(/^(d{1,3}).(d{1,3}).(d{1,3}).(d{1,3})$/) ) {
        var iplong = 0;
        var power  = 1;
        for ( var i=4; i>=1; i-=1 ) {
            iplong += power * parseInt( components[i] );
            power  *= 256;
        }
        return iplong;
    }
    else return -1;
}

var inSubNet = function( ip, subnet ) {   
    var mask, base_ip, long_ip = ip2long(ip);
    if ( ( mask = subnet.match(/^(.*?)/(d{1,2})$/) ) && ( ( base_ip=ip2long( mask[1] ) ) >= 0) ) {
        var freedom = Math.pow(2, 32 - parseInt(mask[2]));
        return (long_ip > base_ip) && (long_ip < base_ip + freedom - 1);
    }
    else return false;
}

The values I’m using are:

ipaddress = '192.168.10.20'
gateway = '192.168.250.1'
mask = '16'

running inSubNet( ipaddress, gateway + '/' + mask ) returns false.

If I change the subnet so the third octet is 10 or lower then it works. If it’s 11 or more then it returns false.

If I’ve understood the subnet correctly I would expect any gateway address 192.168.x.x to return true.

Can some one advise how I can do this.

Thanks