Class: NetAddr::CIDRv6

Inherits:
CIDR
  • Object
show all
Defined in:
lib/cidr.rb

Overview

IPv6 CIDR address - Inherits all methods from NetAddr::CIDR. Addresses of this class are composed of a 128-bit address space.

Instance Attribute Summary

Attributes inherited from CIDR

#address_len, #all_f, #tag, #version

Class Method Summary collapse

Methods inherited from CIDR

#<, #<=>, #==, #>, #[], #allocate_rfc3531, #arpa, #bits, #cmp, #contains?, create, #desc, #enumerate, #fill_in, #initialize, #ip, #is_contained?, #last, #matches?, #multicast_mac, #netmask, #network, #next_ip, #next_subnet, #nth, #range, #remainder, #resize, #resize!, #set_wildcard_mask, #size, #subnet, #succ, #to_i, #to_s, #wildcard_mask

Constructor Details

This class inherits a constructor from NetAddr::CIDR

Class Method Details

.unique_local(eui) ⇒ Object

Synopsis

Generate an IPv6 Unique Local CIDR address based on the algorithm described in RFC 4193.

From the RFC:

1) Obtain the current time of day in 64-bit NTP format [NTP].

2) Obtain an EUI-64 identifier from the system running this

algorithm.  If an EUI-64 does not exist, one can be created from
a 48-bit MAC address as specified in [ADDARCH].  If an EUI-64
cannot be obtained or created, a suitably unique identifier,
local to the node, should be used (e.g., system serial number).

3) Concatenate the time of day with the system-specific identifier

in order to create a key.

4) Compute an SHA-1 digest on the key as specified in [FIPS, SHA1];

the resulting value is 160 bits.

5) Use the least significant 40 bits as the Global ID.

6) Concatenate FC00::/7, the L bit set to 1, and the 40-bit Global

ID to create a Local IPv6 address prefix.

Example: eui = NetAddr::EUI.create(‘aabb.ccdd.eeff’) NetAddr::CIDRv6.unique_local(eui) => fdb4:3014:e277:0000:0000:0000:0000:0000/48

Arguments:

  • NetAddr::EUI object

Returns:

  • CIDRv6 object



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# File 'lib/cidr.rb', line 2152

def CIDRv6.unique_local(eui)

    if (eui.kind_of?(NetAddr::EUI48) )
        eui = eui.to_eui64.to_s
    elsif (eui.kind_of?(NetAddr::EUI64) )
        eui = eui.to_s
    else
        raise ArgumentError, "Expected NetAddr::EUI object but #{eui.class} received."
    end

    ntp_time = ''

    # get current time (32-bits), convert to 4-byte string, and append to ntp_time
    time = Time.now.to_i
    4.times do
        ntp_time.insert(0, (time & 0xff).chr )
        time = time >> 8
    end

    # create 32-bit fractional, convert to 4-byte string, and append to ntp_time
    fract = rand(2**32-1)
    4.times do
        ntp_time.insert(0, (fract & 0xff).chr )
        fract = fract >> 8
    end

    # create sha1 hash
    pre_hash = ntp_time << eui
    gid = Digest::SHA1.hexdigest(pre_hash).slice!(30..39)
    addr = 'fd' << gid << '00000000000000000000'

    return( NetAddr::CIDRv6.new(addr.to_i(16), 0xffffffffffff00000000000000000000 ) )
end