janken

client.rb

require 'socket'
require 'digest/sha2'

Te = %w[rock scissors paper]
Te_cmd = %w[r s p]


if ARGV.length != 2 || !ARGV[1].to_i || ARGV[1].to_i <= 0
  puts File.basename(__FILE__) + " <server_host> <port>"
  exit
end

sock = TCPSocket.new(ARGV[0],ARGV[1].to_i)
puts "connected"

loop do

  key = rand(65536).to_s
  $stdout.write "input your te (r,p,s): "
  te_str = $stdin.gets.strip
  if Te_cmd.include?(te_str)
    te = Te_cmd.index(te_str)
    te_hash = Digest::SHA256.new.update(te.to_s + key)
    sock.puts "jan,#{te_hash}"
    line = sock.gets.strip
    lineitems = line.split(",")
    if(lineitems[0] == "ken")
      server_te = lineitems[1].to_i
      puts "you: #{Te[te]}, server: #{Te[server_te]}"
      case (te - server_te + 3 ) % 3
      when 0
        puts "-> draw"
      when 1
        puts "-> lose"
      when 2
        puts "-> win"
      end
      sock.puts "pon,#{te},#{key}"
    end
  elsif te_str == ""
    sock.puts ""
    exit
  end
end

server.rb

require 'socket'
require 'digest/sha2'

Te = %w[rock scissors paper]


if ARGV.length != 1 || !ARGV[0].to_i || ARGV[0].to_i <= 0
  puts File.basename(__FILE__) + " <port>"
  exit
end

server = TCPServer.new(ARGV[0].to_i)
sock = server.accept
puts "client accepted"

client_te = nil
client_hash = nil
server_te = nil
loop do
  line = sock.gets.strip
  lineitems = line.split(",")
  exit if lineitems.length == 0
  case lineitems[0]
  when "jan"
    puts "received jan"
    client_hash = lineitems[1]
    server_te = rand(3)
    sock.puts "ken,#{server_te}"
    puts "sent ken"
  when "pon"
    puts "received pon"
    client_te = lineitems[1].to_i
    key = lineitems[2]
    if Digest::SHA256.new.update(client_te.to_s + key) == client_hash
      puts "server: #{Te[server_te]}, client: #{Te[client_te]}"
      case (server_te - client_te.to_i + 3) % 3
      when 0
        puts "-> draw"
      when 1
        puts "-> lose"
      when 2
        puts "-> win"
      end
    else
      puts "client cheated ?"
    end
  end
end