NewInstance

Today I used commons-net to verify when an IP address is in a subnet specified in CIDR notation. So, I got a bug.

This code:

SubnetUtils utils = new SubnetUtils("77.24.0.0/16");
System.out.println("lower address: " + utils.getInfo().getLowAddress());
System.out.println("higher address: " + utils.getInfo().getHighAddress());
System.out.println("77.23.255.254 is in range? :" + utils.getInfo().isInRange( "77.23.255.254" ));

gives this output:

lower address: 77.24.0.1
higher address: 77.24.255.254
77.23.255.254 is in range? :true

Obviously the last ip is not in range...

From the sources you see how the isInRange is implemented:

private boolean isInRange(int address)      { return ((address-low()) <= (high()-low())); }

Wrong.

So I fixed in my caller code with a my implementation of isInRange:

private boolean isInRange( SubnetInfo info, String remoteAddr ) {
    int address = info.asInteger( remoteAddr );
    int low = info.asInteger( info.getLowAddress() );
    int high = info.asInteger( info.getHighAddress() );
    return low <= address && address <= high;
}

Unfortunately low and high are not accessible, so I had to convert to int from the string representation.