class IPAddress::IPv6::Mapped

It is usually identified as a IPv4 mapped IPv6 address, a particular IPv6 address which aids the transition from IPv4 to IPv6. The structure of the address is

::ffff:w.y.x.z

where w.x.y.z is a normal IPv4 address. For example, the following is a mapped IPv6 address:

::ffff:192.168.100.1

IPAddress is very powerful in handling mapped IPv6 addresses, as the IPv4 portion is stored internally as a normal IPv4 object. Let's have a look at some examples. To create a new mapped address, just use the class builder itself

ip6 = IPAddress::IPv6::Mapped.new "::ffff:172.16.10.1/128"

or just use the wrapper method

ip6 = IPAddress "::ffff:172.16.10.1/128"

Let's check it's really a mapped address:

ip6.mapped?
  #=> true

ip6.to_string
  #=> "::FFFF:172.16.10.1/128"

Now with the ipv4 attribute, we can easily access the IPv4 portion of the mapped IPv6 address:

ip6.ipv4.address
  #=> "172.16.10.1"

Internally, the IPv4 address is stored as two 16 bits groups. Therefore all the usual methods for an IPv6 address are working perfectly fine:

ip6.to_hex
  #=> "00000000000000000000ffffac100a01"

ip6.address
  #=> "0000:0000:0000:0000:0000:ffff:ac10:0a01"

A mapped IPv6 can also be created just by specify the address in the following format:

ip6 = IPAddress "::172.16.10.1"

That is, two colons and the IPv4 address. However, as by RFC, the ffff group will be automatically added at the beginning

ip6.to_string
  => "::ffff:172.16.10.1/128"

making it a mapped IPv6 compatible address.

Attributes

ipv4[R]

Access the internal IPv4 address

Public Class Methods

new(str) click to toggle source

Creates a new IPv6 IPv4-mapped address

ip6 = IPAddress::IPv6::Mapped.new "::ffff:172.16.10.1/128"

ipv6.ipv4.class
  #=> IPAddress::IPv4

An IPv6 IPv4-mapped address can also be created using the IPv6 only format of the address:

ip6 = IPAddress::IPv6::Mapped.new "::0d01:4403"

ip6.to_string
  #=> "::ffff:13.1.68.3"
Calls superclass method IPAddress::IPv6::new
# File lib/ipaddress_2/ipv6.rb, line 1422
def initialize(str)
  string, netmask = str.split("/")
  if string =~ /\./ # IPv4 in dotted decimal form
    @ipv4 = IPAddress::IPv4.extract(string)
  else # IPv4 in hex form
    groups = IPAddress::IPv6.groups(string)
    @ipv4 = IPAddress::IPv4.parse_u32((groups[-2]<< 16)+groups[-1])
  end
  super("::ffff:#{@ipv4.to_ipv6}/#{netmask}")
end

Public Instance Methods

mapped?() click to toggle source

Checks if the IPv6 address is IPv4 mapped

ip6 = IPAddress "::ffff:172.16.10.1/128"

ip6.mapped?
  #=> true
# File lib/ipaddress_2/ipv6.rb, line 1468
def mapped?
  true
end
to_s() click to toggle source

Similar to IPv6#to_s, but prints out the IPv4 address in dotted decimal format

ip6 = IPAddress "::ffff:172.16.10.1/128"

ip6.to_s
  #=> "::ffff:172.16.10.1"
# File lib/ipaddress_2/ipv6.rb, line 1442
def to_s
  "::ffff:#{@ipv4.address}"
end
to_string() click to toggle source

Similar to IPv6#to_string, but prints out the IPv4 address in dotted decimal format

ip6 = IPAddress "::ffff:172.16.10.1/128"

ip6.to_string
  #=> "::ffff:172.16.10.1/128"
# File lib/ipaddress_2/ipv6.rb, line 1456
def to_string
  "::ffff:#{@ipv4.address}/#@prefix"
end