#!/usr/bin/env ruby -w

##
# A module for retrieving IP adresses from ifconfig (tested on FreeBSD)

module GetIP

  IFCONFIG_IP4_RE = /inet ([^\s]+) netmask ([^\s]+) broadcast ([^\s]+)/
  IFCONFIG_IP6_RE = /inet6 ([^\s]+) prefixlen ([^\s]+) scopeid ([^\s]+)/
  IFCONFIG_IP6_LINK_RE = /inet6 (fe80[^\s]+) prefixlen ([^\s]+) scopeid ([^\s]+)/

  ##
  # Retrieve the ipv4 addr, netmask, and broadcast addr for +interface+

  def self.ip4_addr_for(interface)
    `ifconfig #{interface}` =~ IFCONFIG_IP4_RE

    return [$1, $2, $3]
  end

  ##
  # Retrieve the ip6 link-level addr, prefixlength, and scope id for
  # +interface+

  def self.ip6_link_for(interface)
    `ifconfig #{interface}` =~ IFCONFIG_IP6_LINK_RE
    return [$1, $2, $3]
  end

  ##
  # Retrieve all ipv6 addrs for +interface+, in addr, prefixlength, scope id
  # format.

  def self.ip6_addrs_for(interface)
    addrs = []
    `ifconfig #{interface}`.gsub(IFCONFIG_IP6_RE) {
      addrs << [$1, $2, $3]
    }
    return addrs
  end

end

if $0 == __FILE__

  addr = ARGV.shift
  unless addr then
    puts "usage: #{$0} interface"
    exit
  end

  printf("#{addr} has IPv4 address: %s\n\tnetmask %s\n\tand broadcasts on %s\n",
    *GetIP.ip4_addr_for(addr))

  if ip6_addrs = GetIP.ip6_addrs_for(addr) then
    puts "#{addr} has ip6 addrs:"

    ip6_addrs.each do |ip6addr, prefix, scopeid|
      puts "\taddr: #{ip6addr}, prefix length: #{prefix}, scopeid #{scopeid}"
    end
  end

end