MyIcmpSocket.rb

require 'socket'

class MyIcmpSocket
  ICMP_ECHO_REQUEST_TYPE = 8
  ICMP_ECHO_REQUEST_CODE = 0
  ICMP_HEADER_SIZE = 8

  def initialize
    @socket = Socket.new(Socket::AF_INET, Socket::SOCK_RAW, Socket::IPPROTO_ICMP)
  end

  def ping(host)
    icmp_id = Process.pid & 0xffff
    icmp_seq = 0
    icmp_data = "ping #{host} packet"

    # Construct ICMP echo request packet
    icmp_header = [ICMP_ECHO_REQUEST_TYPE, ICMP_ECHO_REQUEST_CODE, 0, icmp_id, icmp_seq].pack('CCnS>S>')
    icmp_checksum = calc_checksum(icmp_header + icmp_data)
    icmp_packet = [ICMP_ECHO_REQUEST_TYPE, ICMP_ECHO_REQUEST_CODE, icmp_checksum, icmp_id, icmp_seq, icmp_data].pack('CCnS>S>a*')

    # Send ICMP echo request packet and receive response
    sockaddr = Socket.sockaddr_in(0, host)
    start_time = Time.now
    @socket.send(icmp_packet, 0, sockaddr)
    response_packet, sockaddr = @socket.recvfrom(1024)
    end_time = Time.now

    # Parse ICMP echo response packet
    response_header = response_packet[0, ICMP_HEADER_SIZE]
    response_type, response_code, response_checksum, response_id, response_seq = response_header.unpack('CCnS>S>')
    raise "Invalid ICMP echo response packet" unless response_type == 0 && response_code == 0 && response_id == icmp_id && response_seq == icmp_seq
    round_trip_time = (end_time - start_time) * 1000

    # Return round-trip time
    round_trip_time
  end

  private

  def calc_checksum(data)
    sum = 0
    data.scan(/.{2}/m).map { |word| sum += word.unpack('n')[0] }
    sum = (sum >> 16) + (sum & 0xffff)
    sum += sum >> 16
    ~sum & 0xffff
  end
end

# This code creates a raw socket using Socket, which allows it to send and
# receive ICMP packets directly. The ping method constructs an ICMP echo
# request packet, sends it to the specified host, and receives the response.
# The round-trip time is then calculated and returned. The calc_checksum
# method is used to calculate the checksum for the ICMP packet.