= ruby-ip library

This is a library for manipulating IP addresses.

== Installation

Gem:: <tt>gem install ruby-ip</tt>
Source:: <tt>git clone git://github.com/deploy2/ruby-ip.git</tt>
Docs:: http://deploy2.github.com/ruby-ip/

== Feature overview

* Create from string and to string

    require 'ip'
    ip = IP.new("192.0.2.53/24")
    ip.to_s       # "192.0.2.53/24"
    ip.to_i       # 3221226037
    ip.to_hex     # "c0000235"
    ip.to_addr    # "192.0.2.53"
    ip.pfxlen     # 24

* Qualify IP address with "routing context" (VRF)

    ip = IP.new("192.0.2.53/24@cust1")
    ip.to_s       # "192.0.2.53/24@cust1"
    ip.to_addrlen # "192.0.2.53/24"
    ip.ctx        # "cust1"

* Clean implementation of IP::V4 and IP::V6 as subclasses of IP

    ip1 = IP.new("192.0.2.53/24")       #<IP::V4 192.0.2.53/24>
    ip2 = IP.new("2001:db8:be00::/48")  #<IP::V6 2001:db8:be00::/48>
    ip1.is_a?(IP::V4)                   # true

* Create directly from integers or hex

    ip = IP::V4.new(3221226037, 24, "cust1")
    ip = IP::V4.new("c0000235", 24, "cust1")

* Netmask manipulation

    ip = IP.new("192.0.2.53/24")
    ip.network         #<IP::V4 192.0.2.0/24>
    ip.network(1)      #<IP::V4 192.0.2.1/24>
    ip.broadcast       #<IP::V4 192.0.2.255/24>
    ip.broadcast(-1)   #<IP::V4 192.0.2.254/24>
    ip.mask            # 255
    ip.size            # 256
    ip.netmask.to_s    # "255.255.255.0"
    ip.wildmask.to_s   # "0.0.0.255"

* Address masking

    ip = IP.new("192.0.2.53/24")
    ip.offset?         # true
    ip.offset          # 53
    ip.mask!
    ip.to_s            # "192.0.2.0/24"
    ip.offset?         # false

* Simple IP arithmetic

    ip = IP.new("192.0.2.53/24")
    ip + 4             #<IP::V4 192.0.2.57/24>
    ip | 7             #<IP::V4 192.0.2.55/24>
    ip ^ 7             #<IP::V4 192.0.2.50/24>
    ~ip                #<IP::V4 63.255.253.202/24>

* Convert to and from a compact Array representation

    ip1 = IP.new("192.0.2.53/24@cust1")
    ip1.to_a     # ["v4", 3221226037, 24, "cust1"]

    ip2 = IP.new(["v4", 3221226037, 24, "cust1"])
    ip1 == ip2   # true

* Hex array representation, useful when talking to languages which don't
  have Bignum support

    ip1 = IP.new("2001:db8:be00::/48@cust1")
    ip1.to_ah    # ["v6", "20010db8be0000000000000000000000", 48, "cust1"]

    ip2 = IP.new(["v6", "20010db8be0000000000000000000000", 48, "cust1"])
    ip1 == ip2   # true

* Addresses are Comparable, sortable, and can be used as Hash keys

== Why not IPAddr?

Ruby bundles an IPAddr class (ipaddr.rb). However there are a number of
serious problems with this library.

1. Given an IP address with a netmask or prefix (e.g. 192.0.2.0/24) it's
   very hard to get access to the netmask part. It involves digging around
   instance variables.

2. It's impossible to deal with an off-base address with prefix, because
   IPAddr forcibly masks it to the base. e.g. 192.0.2.53/24 is stored as
   192.0.2.0/24

3. IPAddr uses calls to the socket library to validate IP addresses, and
   this can trigger spurious DNS lookups when given an invalid IP address.
   ruby-ip does not depend on the socket library at all, unless you
   require 'ip/socket' to have access to the Socket::AF_INET and
   Socket::AF_INET6 constants.

== Copying

You may use, distribute and modify this software under the same terms as
ruby itself (see LICENSE.txt and COPYING.txt)