Module: Racket::L3::Misc

Defined in:
lib/racket/l3/misc.rb

Overview

Miscelaneous L3 helper methods

Class Method Summary collapse

Class Method Details

.checksum(data) ⇒ Object

Calculate the checksum. 16 bit one’s complement of the one’s complement sum of all 16 bit words



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# File 'lib/racket/l3/misc.rb', line 144

def Misc.checksum(data)
  num_shorts = data.length / 2
  checksum = 0
  count = data.length
  
  data.unpack("S#{num_shorts}").each { |x|
    checksum += x
    count -= 2
  }

  if (count == 1)
    checksum += data[data.length - 1]
  end

  checksum = (checksum >> 16) + (checksum & 0xffff)
  checksum = ~((checksum >> 16) + checksum) & 0xffff
  ([checksum].pack("S*")).unpack("n*")[0]
end

.compressipv6(ipv6) ⇒ Object

Compress an IPv6 address Inspired by Daniele Bellucci and jacked from ipaddr



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# File 'lib/racket/l3/misc.rb', line 75

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

.ipv42long(ip) ⇒ Object

given a “dotted quad” representing an IPv4 address, return the integer representation



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# File 'lib/racket/l3/misc.rb', line 138

def Misc.ipv42long(ip)
  IPAddr.new(ip).to_i
end

.ipv62long(ip) ⇒ Object

given a string representing an IPv6 address, return the integer representation



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# File 'lib/racket/l3/misc.rb', line 103

def Misc.ipv62long(ip)
  IPAddr.new(ip).to_i
end

.linklocaladdr(mac) ⇒ Object

Compute link local address for a given mac address From Daniele Bellucci



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# File 'lib/racket/l3/misc.rb', line 50

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

.long2ipv4(long) ⇒ Object

given an IPv4 address packed as an integer return the friendly “dotted quad”



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# File 'lib/racket/l3/misc.rb', line 35

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

.long2ipv6(long, compress = true) ⇒ Object

Given a long, convert it to an IPv6 address, optionally compressing the address returned



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# File 'lib/racket/l3/misc.rb', line 58

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

.randomipv4 ⇒ Object 



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# File 'lib/racket/l3/misc.rb', line 44

def Misc.randomipv4
  Misc.long2ipv4(rand(2**32))
end

.randomipv6 ⇒ Object 



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# File 'lib/racket/l3/misc.rb', line 97

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

.soll_mcast_addr6(addr) ⇒ Object

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



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# File 'lib/racket/l3/misc.rb', line 114

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

.soll_mcast_mac(addr) ⇒ Object 



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# File 'lib/racket/l3/misc.rb', line 125

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