Class: Icmphdr

Inherits:
Object
  • Object
show all
Defined in:
lib/emtraceroute/icmp.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data = "") ⇒ Icmphdr 



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# File 'lib/emtraceroute/icmp.rb', line 9

def initialize data=""
  @type = 8
  @code = 0
  @cksum = 0
  @id = $$
  @sequence = 0
  @data = data
end

Instance Attribute Details

#cksum ⇒ Object

This represents an ICMP packet header.

Icmphdr#assemble packages the packet Imphdr.checsum calc checksum Icmphdr.disassemble disassembles the packet



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# File 'lib/emtraceroute/icmp.rb', line 8

def cksum
  @cksum
end

#code ⇒ Object

This represents an ICMP packet header.

Icmphdr#assemble packages the packet Imphdr.checsum calc checksum Icmphdr.disassemble disassembles the packet



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# File 'lib/emtraceroute/icmp.rb', line 8

def code
  @code
end

#data ⇒ Object

This represents an ICMP packet header.

Icmphdr#assemble packages the packet Imphdr.checsum calc checksum Icmphdr.disassemble disassembles the packet



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# File 'lib/emtraceroute/icmp.rb', line 8

def data
  @data
end

#id ⇒ Object

This represents an ICMP packet header.

Icmphdr#assemble packages the packet Imphdr.checsum calc checksum Icmphdr.disassemble disassembles the packet



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# File 'lib/emtraceroute/icmp.rb', line 8

def id
  @id
end

#sequence ⇒ Object

This represents an ICMP packet header.

Icmphdr#assemble packages the packet Imphdr.checsum calc checksum Icmphdr.disassemble disassembles the packet



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# File 'lib/emtraceroute/icmp.rb', line 8

def sequence
  @sequence
end

#type ⇒ Object

This represents an ICMP packet header.

Icmphdr#assemble packages the packet Imphdr.checsum calc checksum Icmphdr.disassemble disassembles the packet



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# File 'lib/emtraceroute/icmp.rb', line 8

def type
  @type
end

Class Method Details

.checksum(data) ⇒ Object 



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# File 'lib/emtraceroute/icmp.rb', line 26

def self.checksum data
  data += '\0' if data.size & 1 == 1
  cksum = data.unpack("n*")[0..(data.size >> 1)].inject(&:+)
  cksum = (cksum >> 16) + (cksum & 0xffff)
  cksum += (cksum >> 16)
  cksum = (cksum & 0xffff) ^ 0xffff
  cksum
end

.disassemble(data) ⇒ Object 



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# File 'lib/emtraceroute/icmp.rb', line 35

def self.disassemble data
  icmp = Icmphdr.new
  pkt = data.unpack('CCnnn')
  icmp.type, icmp.code, icmp.cksum, icmp.id, icmp.sequence = pkt
  icmp
end

Instance Method Details

#assemble ⇒ Object 



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# File 'lib/emtraceroute/icmp.rb', line 18

def assemble
  part1 = [@type, @code].pack('C*')
  part2 = [@id, @sequence].pack('n*')
  cksum = Icmphdr.checksum(part1 + "\000\000" + part2 + @data)
  cksum = [cksum].pack('n')
  part1 + cksum + part2 + @data
end