Class: IPFrag::Generator

Inherits:
Object
  • Object
show all
Defined in:
lib/ip_frag/generator.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size, mtu) ⇒ Generator

Returns a new instance of Generator.



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# File 'lib/ip_frag/generator.rb', line 3

def initialize(size, mtu)
  @size = size
  @mtu = mtu
  check_size_mtu
end

Instance Attribute Details

#dst_ip ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 114

def dst_ip
  @dst_ip ||= '200.200.200.2'
end

#dst_mac ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 122

def dst_mac
  @dst_mac ||= '00:00:00:00:00:02'
end

#dst_port ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 130

def dst_port
  @dst_port ||= 2000
end

#src_ip ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 110

def src_ip
  @src_ip ||= '200.200.200.1'
end

#src_mac ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 118

def src_mac
  @src_mac ||= '00:00:00:00:00:01'
end

#src_port ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 126

def src_port
  @src_port ||= 1000
end

Instance Method Details

#check_size_mtu ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 99

def check_size_mtu
  
  if @size <= @mtu
    raise "Size #{@size} MUST be big than Mtu #{@mtu}."
  end
  
  if @mtu <= 0
    raise "Mtu MUST be an integer big than ZERO"
  end
end

#contant(size, ip) ⇒ Object

生成特定长度的 UDP 报文



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# File 'lib/ip_frag/generator.rb', line 148

def contant(size, ip)
  return @udp_packet if @udp_packet
  udp = Mu::Pcap::UDP.new(src_port, dst_port)
  udp.payload = 'a' * size
  udp_packet_str = StringIO.new
  udp.write(udp_packet_str, ip)
  udp_packet_str.rewind
  @udp_packet ||= udp_packet_str.read
end

#make_ether_packet {|packet| ... } ⇒ Object

Yields:

  • (packet) 


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# File 'lib/ip_frag/generator.rb', line 82

def make_ether_packet
  packet = Mu::Pcap::Ethernet.new(src_mac, dst_mac)
  packet.type = Mu::Pcap::Ethernet::ETHERTYPE_IP
  yield packet
  packet
end

#make_ip_packet(size) {|ip| ... } ⇒ Object

Yields:

  • (ip) 


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# File 'lib/ip_frag/generator.rb', line 75

def make_ip_packet(size)
  ip = Mu::Pcap::IPv4.new(src_ip, dst_ip)
  ip.proto = Mu::Pcap::IP::IPPROTO_UDP
  yield ip if block_given?
  ip
end

#make_offset(offset, last = false) ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 89

def make_offset(offset, last = false)
  offset = offset >> 3
  
  flag = 1
  if last
    flag = 0
  end
  ( flag << 13) | offset
end

#packet_count ⇒ Object

Get total packet size, it depends on @size and @mtu



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# File 'lib/ip_frag/generator.rb', line 57

def packet_count
  count, left = @size.divmod(packet_offset)
  if left != 0
    count += 1
  end
  count
end

#packet_left ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 69

def packet_left
  left = @size % packet_offset
  left = packet_offset if left == 0
  left
end

#packet_offset ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 65

def packet_offset
  @mtu & (~7)
end

#split_to_ethernet_packet ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 35

def split_to_ethernet_packet
  ip_packets = split_to_ip_packet
  ip_packets.map do |ip_packet|
    make_ether_packet do |e|
      e.payload = ip_packet
      e.type
    end
  end
end

#split_to_ip_packet ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 9

def split_to_ip_packet
  ret = []

  offset = 0
  ret << make_ip_packet(packet_offset) do |p|
    p.offset = make_offset(offset)
    p.payload = udp_offset( contant(udp_size_from(@size), p), 1)
  end
  offset += packet_offset
  
  (packet_count - 2).times do |i|
    ret << make_ip_packet(packet_offset) do |p|
      p.offset = make_offset(offset)
      p.payload = udp_offset( contant(udp_size_from(@size), p), i+2)
    end
    offset += packet_offset
  end
  
  ret << make_ip_packet(packet_left) do |p|
    p.offset = make_offset(offset, true)
    p.payload = udp_offset( contant(udp_size_from(@size), p), packet_count)
  end
  
  ret
end

#udp_offset(udp, packet_num) ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 137

def udp_offset( udp, packet_num)
  size = @mtu
  udp[(packet_num-1)*size..packet_num*size -1 ]
end

#udp_size_from(ip_size) ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 142

def udp_size_from(ip_size)
  ip_size - 8
end

#write_dat(path = '.') ⇒ Object 



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# File 'lib/ip_frag/generator.rb', line 45

def write_dat(path = '.')
  split_to_ethernet_packet.each_with_index do |p, i|
    file_name = "#{i+1}.dat"
    file = File.open( File.join(path, file_name), 'wb') do |f|
      p.write(f)
    end
  end
end