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From: Neil <neil.matatall@gmail.com>
To: Rack Development <rack-devel@googlegroups.com>
Subject: Session collisions on rails 3.1rc4 (authlogic, omniauth, memcache store, passenger)
Date: Mon, 25 Jul 2011 11:22:20 -0700 (PDT)	[thread overview]
Message-ID: <f4416221-592c-4b98-af7d-f8f98170d3df@t8g2000prm.googlegroups.com> (raw)

While it's entirely possible that this issue is caused by some other
factor, but we are getting session collisions as well as an issue
where one user is getting another user's session.  This is clearly
bad, but I cannot for the life of me figure out how this could even
happen in the first place.  The code looks thread safe to me, and a
quick discussion on #ruby-lang seems to support that.

1.  Session IDs are being generated in the same sequence (uses
securerandom -> openssl which does not have a static seed)
2.  Threads.  Looks good to me.
3.  Maybe memcached is returning something other than "STORED/
NOT_STORED" for @pool.add(sid, session), but the operation still
4.  Gnomes.

Any input is GREATLY appreciated.  Please don't say "it's an RC, what
do you expect?" :)

From https://github.com/rack/rack/blob/master/lib/rack/session/memcache.rb
      def generate_sid
        loop do
          sid = super
          break sid unless @pool.get(sid, true)

      def get_session(env, sid)
        with_lock(env, [nil, {}]) do
          unless sid and session = @pool.get(sid)
            sid, session = generate_sid, {}
            unless /^STORED/ =~ @pool.add(sid, session)
              raise "Session collision on '#{sid.inspect}'"
          [sid, session]

      def set_session(env, session_id, new_session, options)
        expiry = options[:expire_after]
        expiry = expiry.nil? ? 0 : expiry + 1

        with_lock(env, false) do
          @pool.set session_id, new_session, expiry

             reply	other threads:[~2011-07-25 18:38 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-25 18:22 Neil [this message]
2011-07-25 20:23 ` Joshua Ballanco
2011-07-25 21:12   ` Neil Matatall
2011-07-28 19:54   ` Neil Matatall
2011-08-03 10:32     ` Joshua Ballanco
2011-08-04 23:26       ` James Tucker

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