rexecutor

#
#: Filename    : rexecutor.rb
#: Title       : rExecutor
#: Author      : "Iarmin" <[email protected]>
#: Version     : 0.1
#: Description : A little webserver, that accepts JSON input via GET method. Supports authentication code and executes the given command.
#: Gems        : json SystemTimer
#: Installer   :
#

require 'socket'
require 'cgi'
require 'rubygems'
require 'json'
require 'open3'
require 'system_timer'

$AUTHCODE     = "<CODE>"    # the authentication code
$LISTEN_IP    = "0.0.0.0"   # Bound IP
$LISTEN_PORT  = 9091        # Port to listen
$ALLOWED_CMDS = [ "df", "uname" ]   # allowed commands


class HttpServer
  def initialize(session, request)
    @session = session
    @request = request
  end

  def serve()
    begin
      request = @request.chomp
      raise if ! request.start_with?("GET /")
      request.gsub!(/^GET \//,"").gsub!(/ .*/,"")
      request = CGI::unescape( request )
      request = JSON.parse( request.chomp )

      response = '[]'
      begin
        SystemTimer.timeout_after( 6 ) do
        response = process( request )
      end
      rescue Timer::Timeout
        response = { :error => "Timeout" }
      rescue Exception => e
        response = { :error => e.to_s }
      end
      response = response.to_json

      contentType = "text/plain"
      @session.print "HTTP/1.1 200/OK\r\nServer: Remote Executor\r\nContent-type: text/plain\r\n\r\n"
      @session.print( "#{response}\n" )
    rescue
      @session.print "HTTP/1.1 400/ERROR\r\nInvalid request\r\n\r\n"
    ensure
      @session.close
    end
  end

  def process( request )
    response = {}
    begin
      raise "Invalid auth code" if request["auth"] != $AUTHCODE
      _exec = request["exec"]
      unallowed = true
      $ALLOWED_CMDS.each do |cmd|
        unallowed = false if _exec == cmd
      end
      raise "Restricted command" if unallowed
      stdin, stdout, stderr, wait_thr = Open3.popen3( _exec )
      response = { :stdout => stdout.read, :stderr => stderr.read }
    rescue Exception => e
        response = { :error => s.to_s }
    end
  end
end

server = TCPServer.new($LISTEN_IP, $LISTEN_PORT)

loop do
  session = server.accept
  request = session.gets

  Thread.start(session, request) do |session, request|
    HttpServer.new(session, request).serve()
  end
end