/lib/racket/l3/misc.rb

# $Id: misc.rb 14 2008-03-02 05:42:30Z warchild $
#
# Copyright (c) 2008, Jon Hart 
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#     * Redistributions of source code must retain the above copyright
#       notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above copyright
#       notice, this list of conditions and the following disclaimer in the
#       documentation and/or other materials provided with the distribution.
#     * Neither the name of the <organization> nor the
#       names of its contributors may be used to endorse or promote products
#       derived from this software without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY Jon Hart ``AS IS'' AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL Jon Hart BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
require 'ipaddr'
module Racket
module L3
  # Miscelaneous L3 helper methods
  module Misc
    # given an IPv4 address packed as an integer
    # return the friendly "dotted quad"
    def Misc.long2ipv4(long)
      quad = Array.new(4)
      quad[0] = (long >> 24) & 255
      quad[1] = (long >> 16) & 255
      quad[2] = (long >> 8 ) & 255
      quad[3] = long & 255
      quad.join(".")
    end

    def Misc.randomipv4
      Misc.long2ipv4(rand(2**32))
    end
    
    # Compute link local address for a given mac address
    # From Daniele Bellucci
    def Misc.linklocaladdr(mac)
      mac = mac.split(":")
      mac[0] = (mac[0].to_i(16) ^ (1 << 1)).to_s(16)
      ["fe80", "", mac[0,2].join, mac[2,2].join("ff:fe"), mac[4,2].join].join(":")
    end
    
    # Given a long, convert it to an IPv6 address, 
    # optionally compressing the address returned
    def Misc.long2ipv6(long, compress=true)
      ipv6 = []
      ipv6[0] = long >> 112
      ipv6[1] = (long >> 96) & (0xFFFF)
      ipv6[2] = (long >> 80) & (0xFFFF)
      ipv6[3] = (long >> 64) & (0xFFFF)
      ipv6[4] = (long >> 48) & (0xFFFF)
      ipv6[5] = (long >> 32) & (0xFFFF)
      ipv6[6] = (long >> 16) & (0xFFFF)
      ipv6[7] = long & (0xFFFF)

      ipv6 = ipv6.map { |o| o.to_s(16) }.join(":")
      compress ? Misc.compressipv6(ipv6) : ipv6
    end

    # Compress an IPv6 address
    # Inspired by Daniele Bellucci and jacked from ipaddr
    def Misc.compressipv6(ipv6)
      ipv6.gsub!(/\b0{1,3}([\da-f]+)\b/i, '\1')
      loop do
        break if ipv6.sub!(/\A0:0:0:0:0:0:0:0\Z/, '::')
        break if ipv6.sub!(/\b0:0:0:0:0:0:0\b/, ':')
        break if ipv6.sub!(/\b0:0:0:0:0:0\b/, ':')
        break if ipv6.sub!(/\b0:0:0:0:0\b/, ':')
        break if ipv6.sub!(/\b0:0:0:0\b/, ':')
        break if ipv6.sub!(/\b0:0:0\b/, ':')
        break if ipv6.sub!(/\b0:0\b/, ':')
        break
      end

      ipv6.sub!(/:{3,}/, '::')

      if /\A::(ffff:)?([\da-f]{1,4}):([\da-f]{1,4})\Z/i =~ ipv6
        ipv6 = sprintf('::%s%d.%d.%d.%d', $1, $2.hex / 256, $2.hex % 256, $3.hex / 256, $3.hex % 256)
      end

      ipv6
    end

    def Misc.randomipv6
      Misc.long2ipv6(rand(2**128))
    end

    # given a string representing an IPv6
    # address, return the integer representation
    def Misc.ipv62long(ip)
      IPAddr.new(ip).to_i
    end

    # In addition to the regular multicast addresses, each unicast address
    # has a special multicast address called its solicited-node address. This
    # address is created through a special mapping from the device’s unicast
    # address. Solicited-node addresses are used by the IPv6 Neighbor
    # Discovery (ND) protocol to provide more efficient address resolution
    # than the ARP technique used in IPv4.  
    # From Daniele Bellucci
    def Misc.soll_mcast_addr6(addr)
      h = addr.split(':')[-2, 2] 
      m = []
      m << 'ff'
      m << (h[0].to_i(16) & 0xff).to_s(16)
      m << ((h[1].to_i(16) & (0xff << 8)) >> 8).to_s(16)
      m << (h[1].to_i(16) & 0xff).to_s(16)
      'ff02::1:' + [m[0,2].join, m[2,2].join].join(':')
    end
    
    # 
    def Misc.soll_mcast_mac(addr)
      h = addr.split(':')[-2, 2] 
      m = []
      m << 'ff'
      m << (h[0].to_i(16) & 0xff).to_s(16)
      m << ((h[1].to_i(16) & (0xff << 8)) >> 8).to_s(16)
      m << (h[1].to_i(16) & 0xff).to_s(16)   
      '33:33:' + m.join(':') 
    end


    # given a "dotted quad" representing an IPv4
    # address, return the integer representation
    def Misc.ipv42long(ip)
      IPAddr.new(ip).to_i
    end

    # Calculate the checksum.  16 bit one's complement of the one's
    # complement sum of all 16 bit words
    def Misc.checksum(data)
      checksum = 0
      unpack = "S#{data.length / 2}#{data.length % 2 == 1 ? 'C' : ''}"

      data.unpack(unpack).each { |x|
        checksum += x
      }

      checksum = (checksum >> 16) + (checksum & 0xffff)
      checksum = ~((checksum >> 16) + checksum) & 0xffff
      ([checksum].pack("S*")).unpack("n*")[0]
    end
  end
end
end
# vim: set ts=2 et sw=2: