From: Bryan Richardson <btricha@...>
Date: 2008-01-17T12:12:44+09:00
Subject: Re: Problem with IPAddr

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Todd,

I believe Felix's suggestion is the way to go.  With yours, the addresses
could be different, but as long as the mask was bigger it would still return
true... not correct.  Example:

a = IPAddr.new("192.168.15.5")
b = IPAddr.new("192.168.16.0/24")

a.network_in_network?(b) #==> true

Thanks! -- BTR

On Jan 16, 2008 4:59 PM, Todd Benson <caduceass@gmail.com> wrote:

> On Jan 16, 2008 6:52 AM, fw <fwmailinglists@gmail.com> wrote:
> > On Wed, 2008-01-16 at 14:53 +0900, Bryan Richardson wrote:
> > > Gary,
> > >
> > > Thanks for the reply.  Here's what I get when I try something else:
> > >
> > > irb(main):001:0> require 'ipaddr'
> > > => true
> > > irb(main):002:0> net_1 = IPAddr.new("192.168.0.0/16")
> > > => #<IPAddr: IPv4:192.168.0.0/255.255.0.0>
> > > irb(main):003:0> net_2 = IPAddr.new("192.168.101.0/24")
> > > => #<IPAddr: IPv4:192.168.101.0/255.255.255.0>
> > > irb(main):004:0> net_1.include?(net_2)
> > > => true
> > > irb(main):005:0> net_2.include?(net_1)
> > > => false
> > > irb(main):006:0>
> > >
> > > Makes sense I guess.  Is there any way to tell IPAddr to look at it as
> a
> > > network instead of as an address?  I have a situation where I may come
> > > across an address (ending in .0, so defining a network) where the
> netmask
> > > isn't given, so I assign it as a small network (say /29).  Later on I
> may
> > > come across it again, this time with the netmask defined (say /16),
> and I
> > > want to merge the first one into the second one.  Therefore, each time
> I add
> > > a new network to my database, I compare it to the existing ones to see
> if
> > > any should be merged.  Any suggestions?  Thanks!! -- BTR
> >
> > First I'd like to add that the last octet being 0 does not mean that the
> > IP address is a network address: In the network 10.0.0.0/25, 10.0.1.0 is
> > a host address.
> >
> > IPAddr doesn't seem to have this functionality, but you can add it like
> > this:
> >
> > $ irb
> > irb(main):001:0> require 'ipaddr'
> > => true
> > irb(main):002:0> class IPAddr
> > irb(main):003:1>   def broadcast_addr
> > irb(main):004:2>     _to_string(@addr | (2**32 - 1) - (@mask_addr))
> > irb(main):005:2>   end
> > irb(main):006:1>   def network_in_network?(network)
> > irb(main):007:2>     return false unless self.include?(network)
> > irb(main):008:2>     return false unless
> > self.include?(IPAddr.new(network.broadcast_addr))
> > irb(main):009:2>     return true
> > irb(main):010:2>   end
> > irb(main):011:1> end
> > => nil
> > irb(main):012:0> a = IPAddr.new('192.168.0.128/25'<http://192.168.0.128/25%27>
> )
> > => #<IPAddr: IPv4:192.168.0.128/255.255.255.128>
> > irb(main):013:0> b = IPAddr.new('192.168.0.0/24'<http://192.168.0.0/24%27>
> )
> > => #<IPAddr: IPv4:192.168.0.0/255.255.255.0>
> > irb(main):014:0> a.network_in_network?(b)
> > => false
> > irb(main):015:0> b.network_in_network?(a)
> > => true
> > irb(main):016:0>
> >
> >
> > This works by determining the broadcast address of the network (by ORing
> > the network address with the reverse netmask) and then checking if both
> > network and broadcast address are included in the range you're checking
> > against.
>
> This might work too...
>
> class IPAddr
>  attr_accessor :mask_addr
>  def network_in_network? ipaddr
>    @mask_addr > ipaddr.mask_addr
>  end
> end
>
> Todd
>
>

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