mcquery.rb

require 'socket'
require 'timeout'

class MCQuery
  MAGIC_PREFIX = "\xFE\xFD"
  PACKET_TYPE_CHALLENGE = "\x09"
  PACKET_TYPE_QUERY = "\x00"
  ID = "\x00\x00\x00\x00"
  DEFAULTS = {
    host: "localhost",
    port: 25565,
  }

  def initialize(opts = {})
    @opts = DEFAULTS.merge! opts
  end

  def start
    @socket = UDPSocket.new
    @socket.connect(@opts[:host], @opts[:port])
    @socket.send(MAGIC_PREFIX + PACKET_TYPE_CHALLENGE + ID, 0)
    t = @socket.recvfrom(1460)[0]
    key = t[5...-1].to_i
    @key = Array(key).pack('N')
  end

  def quick
    begin
      timeout(5) do
        begin
          s = TCPSocket.open(@opts[:host], @opts[:port])
        rescue Exception => ex
          return false, ex
        end
        s.write("\xFE")
        data = s.read()
        data = data.gsub("\x00".force_encoding("ASCII-8BIT"), "").gsub("\x1A".force_encoding("ASCII-8BIT"), "").gsub("\xFF".force_encoding("ASCII-8BIT"), "")
        results = data.split("\xA7".force_encoding("ASCII-8BIT"))
        info = {}
        info[:motd] = results[0]
        info[:players] = results[1]
        info[:max] = results[2]
        info[:timestamp] = Time.now
        return info
      end
    rescue Exception => ex
      return false, ex
    end
  end

  def simple
    begin
      timeout(5) do
        start
        query = @socket.send(MAGIC_PREFIX + PACKET_TYPE_QUERY + ID + @key, 0)
        data = @socket.recvfrom(1460)[0]
        buffer = data[5...-1]
        val = {}
        val[:motd], val[:gametype], val[:map], val[:numplayers], val[:maxplayers], buf = buffer.split("\x00", 6)
        val[:timestamp] = Time.now
        return val
      end
    rescue Exception => ex
      return false, ex
    end
  end

  def full
    begin
      timeout(10) do
        start
        query = @socket.send(MAGIC_PREFIX + PACKET_TYPE_QUERY + ID + @key + ID, 0)
        data = @socket.recvfrom(1460)[0]
        buffer = data[11...-1]
        items, players = buffer.split("\x00\x00\x01player_\x00\x00")
        if items[0...8] == 'hostname'
          items = 'motd' + items[8...-1]
        end
        vals = {}
        items = items.split("\x00")
        items.each_with_index do |key, idx|
          next unless idx % 2 == 0
          vals[key] = items[idx + 1]
        end

        vals["motd"] = vals["hostname"]
        vals.delete("hostname")
        vals.delete("um") if vals["um"]

        players = players[0..-2] if players
        
        if players
          vals[:players] = players.split("\x00")
        end
        puts vals
        vals["raw_plugins"] = vals["plugins"]
        parts = vals["raw_plugins"].split(":")
        server = parts[0].strip() if parts[0]
        plugins = []
        if parts.size == 2
          plugins = parts[1].split(";").map {|value| value.strip() }
        end
        vals["plugins"] = plugins
        vals["server"] = server
        vals["timestamp"] = Time.now
        return vals.inject({}){|memo,(k,v)| memo[k.to_sym] = v; memo}
      end
    rescue StandardError => ex
      return false, ex
    end
  end
end