From: m_seki@...
Date: 2002-02-05T12:31:22+09:00
Subject: Re: Controlling access to (druby's) ExtServ#stop_service


> > I think, the owner alone knows reference of ExtServ (= DRbObject).
> > How do others get the reference of ExtServ ?

> What does this do (from drb package: sample/extserv_test.rb)?
>   if (cmd == 'quit') 
>     s.service('itest1').stop_service
>     s.service('itest2').stop_service
>   end
> 
> It does not seem to do anything: the server process keeps running and
> subsequent access to that server still returns itest1 and itest2.

Ooops, he is too talkative. 


> Any idea how to prevent local user from stopping the service?

* DRb protocol do not care about user authentication.
  I think, it is application domain.

* My idea is ..., keep your DRbObjects confidential.
  
* I wrote experimental module called DRbAuth.
  -> http://www2a.biglobe.ne.jp/~seki/ruby/drbauth-0.9.tar.gz



== using DRbAuth

* start sign_server.rb
* patch extserv.rb
* start ExtServManager
* inovke/quit ExtServ

=== start ticket_server.rb

% ruby ticket_server.rb

require 'drb/drb'
require 'drbauth'

class TicketServer
  include DRbUndumped

  def initialize(dict); @dict = dict; end

  def check_sign(ticket)
    salt = Time.now.to_s
    name, g_sign, opt = ticket.sign(salt)
    if @dict[name].nil? or DRbAuth::digest(@dict[name], salt) != g_sign
      raise DRbAuth::DRbAuthError 
    end
    [name, opt]
  end
end

if __FILE__ == $0
  users = { 'mas'=>'mas00', 'seki'=>'seki00' , 'ys' => 'santoso'}

  users.keys.each do |k|
    users[k] = DRbAuth.digest(k, users[k])
  end

  ts = TicketServer.new(users)

  DRb.start_service(ARGV.shift || 'druby://:8472', ts)
  puts DRb.uri

  gets
  exit
end

=== patch drb/extserv.rb

Apply this patch.

@@ -13,8 +13,8 @@
     def initialize(there, name, server=nil)
       @server = server || DRb::primary_server
       @name = name
-      @invoker = DRbObject.new(nil, there)
-      @invoker.regist(name, DRbObject.new(self, @server.uri))
+      ro = DRbObject.new(nil, there)
+      @invoker = ro.regist(name, DRbObject.new(self, @server.uri))
     end
     attr_reader :server


=== start ExtServManager

% ruby extserv_test2.rb server

require 'drb/drb'
require 'drbauth'

class Foo
  include DRbUndumped
  def initialize(str);  @str = str; end
  def hello(it); "#{it}: #{self}"; end
  def to_s; @str; end
end

class MyFront < DRbAuth::Front
  include DRbUndumped

  def initialize(ticket_server, extserv, allow_users=nil)
    super(ticket_server)
    @extserv = extserv
    @user = allow_users
  end

  def regist(name, ro)
    @extserv.regist(name, ro)
    return @extserv
  end

  private
  def fetch(service, user)
    if @user
      raise(DRbAuth::DRbAuthError) unless @user.include?(user)
    end
    return @extserv.service(service)
  end
end

cmd = ARGV.shift
case cmd
when 'itest1', 'itest2'
  require 'drb/extserv'

  front = Foo.new(cmd)
  server = DRb::DRbServer.new(nil, front)
  es = DRb::ExtServ.new(ARGV.shift, ARGV.shift, server)
  server.thread.join

when 'server'
  require 'drb/extservm'

  ts_uri = ARGV.shift || 'druby://localhost:8472'

  DRb::ExtServManager.command['itest1'] = "ruby -I. #{$0} itest1"
  DRb::ExtServManager.command['itest2'] = "ruby -I. #{$0} itest2"
  
  s = DRb::ExtServManager.new
  front = MyFront.new(DRbObject.new(nil, ts_uri), s, ['seki', 'ys'])
  DRb.start_service(nil, front)
  puts DRb.uri
  DRb.thread.join

else
  uri = (cmd == 'quit') ? ARGV.shift : cmd

  print "user: "
  user = gets.chomp
  print "pass: "
  pass = gets.chomp

  DRb.start_service

  s = DRbObject.new(nil, uri)

  ticket = DRbAuth::Ticket.new(user, pass, 'itest1')
  s.checkout(ticket)
  s1 = ticket.retrieve
  f1 = s1.front
  puts f1

  ticket = DRbAuth::Ticket.new(user, pass, 'itest2')
  s.checkout(ticket)
  s2 = ticket.retrieve
  f2 = s2.front
  puts f2

  puts f1.hello(f2)

  if (cmd == 'quit') 
    s1.stop_service
    s2.stop_service
  end
end


=== invoke/quit ExtServ

% ruby extserv_test2.rb druby://.....
user: seki
pass: seki00
....

% ruby extserv_test2.rb quit druby://.....
user: seki
pass: seki00
....


seki.