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Versions: 17
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Contents
require 'bindata'
require 'pio/ethernet_header'
require 'pio/ipv4_header'
module Pio
class Icmp
# Icmp parser.
class Format < BinData::Record
MINIMUM_IP_PACKET_LENGTH = 50
include EthernetHeader
include IPv4Header
endian :big
ethernet_header ether_type: EtherType::IPV4
ipv4_header ip_protocol: ProtocolNumber::ICMP
uint8 :icmp_type
uint8 :icmp_code, initial_value: 0
uint16 :icmp_checksum, value: :calculate_icmp_checksum
uint16 :icmp_identifier
uint16 :icmp_sequence_number
string :echo_data, read_length: :echo_data_read_length
string :padding, read_length: 0, initial_value: :icmp_padding_length
def message_type
icmp_type
end
alias_method :to_binary, :to_binary_s
private
def calculate_icmp_checksum
sum = [icmp_type * 0x100 + icmp_code,
icmp_identifier,
icmp_sequence_number,
*echo_data.unpack('n*')].inject(:+)
~((sum & 0xffff) + (sum >> 16)) & 0xffff
end
def echo_data_read_length
ip_total_length - (ip_header_length * 4) - 8
end
def icmp_padding_length
length = MINIMUM_IP_PACKET_LENGTH -
(ip_header_length * 4) - 8 - echo_data.length
length > 0 ? "\x00" * length : ''
end
end
end
end
Version data entries
17 entries across 17 versions & 1 rubygems