From: Eleanor McHugh <eleanor@...>
Date: 2009-03-01T08:22:07+09:00
Subject: Re: Gets the broadcast address of an IP address

On 28 Feb 2009, at 22:49, Hassan Schroeder wrote:
> On Sat, Feb 28, 2009 at 11:12 AM, Eleanor McHugh
> <eleanor@games-with-brains.com> wrote:
>
>>> ... But is there a way to get automatically the
>>> "192.168.0.255" address thanks to a Ruby method?  I know I can get  
>>> my IP
>>> with IPSocket.getaddress(Socket.gethostname) but I don't see any  
>>> way to
>>> gets its broadcast address.
>
>> The simplest way to do it is to use a regex to change the last term  
>> in the
>> quad:
>>
>> IPSocket.getaddress(Socket.gethostname).gsub!(/.\d{1,3}$/, '.255')
>
> Simple but not necessarily correct  :-)
>
> <http://learn-networking.com/network-design/how-a-broadcast-address-works 
> >

True, but I'm not sure the general case is so easy on the eye ;p

subnet_mask = [ 255, 255, 255, 0 ]
IPSocket 
.getaddress(Socket.gethostname).split('.').zip(subnet_mask).collect { | 
(i, m)| ((~m) & 255) | i.to_i }.join(".")


Ellie

Eleanor McHugh
Games With Brains
http://slides.games-with-brains.net
----
raise ArgumentError unless @reality.responds_to? :reason