Puppet Function: wmflib::cidr_last_address

Defined in:
modules/wmflib/lib/puppet/functions/wmflib/cidr_last_address.rb
Function type:
Ruby 4.x API

Summary

returns the last usable address of a cidr network

Overview

wmflib::cidr_last_address(Variant[Stdlib::IP::Address::V4::CIDR,Stdlib::IP::Address::V6::CIDR] $ip) ⇒ Variant[Stdlib::IP::Address::V4::Nosubnet,Stdlib::IP::Address::V6::Nosubnet]

SPDX-License-Identifier: Apache-2.0

Examples:

calling the function

wmflib::cidr_last_address('192.168.2.0/24')
=> '192.168.2.255'
wmflib::cidr_last_address('fe80::800:27ff:fe00:0/64')
=> 'fe80::ffff:ffff:ffff:ffff'

Parameters:

  • ip (Variant[Stdlib::IP::Address::V4::CIDR,Stdlib::IP::Address::V6::CIDR]) —

    IPv6 or IPv4 address in CIDR notation

Returns:

  • (Variant[Stdlib::IP::Address::V4::Nosubnet,Stdlib::IP::Address::V6::Nosubnet]) —

    IPv6 or IPv4 network/net address



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# File 'modules/wmflib/lib/puppet/functions/wmflib/cidr_last_address.rb', line 4

Puppet::Functions.create_function(:'wmflib::cidr_last_address') do
  # @param ip IPv6 or IPv4 address in CIDR notation
  # @return IPv6 or IPv4 network/net address
  # @example calling the function
  #   wmflib::cidr_last_address('192.168.2.0/24')
  #   => '192.168.2.255'
  #   wmflib::cidr_last_address('fe80::800:27ff:fe00:0/64')
  #   => 'fe80::ffff:ffff:ffff:ffff'
  dispatch :cidr_last_address do
    param 'Variant[Stdlib::IP::Address::V4::CIDR,Stdlib::IP::Address::V6::CIDR]', :ip
    return_type 'Variant[Stdlib::IP::Address::V4::Nosubnet,Stdlib::IP::Address::V6::Nosubnet]'
  end

  def cidr_last_address(cidr_s)
    # @param cidr_s
    #   The cidr to be inspected
    #
    # @return [str]
    #   The String representation of the last address in the subnet
    # @note
    #   This functions uses bitwise manipulation to compute the mask and the last
    #   address in the subnet. The simple strategy of using cidr.to_range.last
    #   would loop over all addresses, which is computationally expensive for large
    #   IPv6 subnets (as in minutes), whereas this is instantaneous.
    cidr = IPAddr.new(cidr_s)
    mask_bit_length = cidr.ipv6? ? 128 : 32
    shifted_mask = 1 << mask_bit_length
    mask = shifted_mask - (1 << (mask_bit_length - cidr.prefix))
    last_address = IPAddr.new(cidr | (~mask & (shifted_mask - 1)), cidr.family)
    last_address.to_s
  end
end