3 files changed, 232 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch.rb b/actionpack/lib/action_dispatch.rb
index c13850f378..1e92d14542 100644
--- a/actionpack/lib/action_dispatch.rb
+++ b/actionpack/lib/action_dispatch.rb
@@ -83,6 +83,7 @@ module ActionDispatch
     autoload :AbstractStore, 'action_dispatch/middleware/session/abstract_store'
     autoload :CookieStore,   'action_dispatch/middleware/session/cookie_store'
     autoload :MemCacheStore, 'action_dispatch/middleware/session/mem_cache_store'
+    autoload :CacheStore,    'action_dispatch/middleware/session/cache_store'
   end
 
   autoload_under 'testing' do
diff --git a/actionpack/lib/action_dispatch/middleware/session/cache_store.rb b/actionpack/lib/action_dispatch/middleware/session/cache_store.rb
new file mode 100644
index 0000000000..d3b6fd12fa
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/session/cache_store.rb
@@ -0,0 +1,50 @@
+require 'action_dispatch/middleware/session/abstract_store'
+require 'rack/session/memcache'
+
+module ActionDispatch
+  module Session
+    # Session store that uses an ActiveSupport::Cache::Store to store the sessions. This store is most useful
+    # if you don't store critical data in your sessions and you don't need them to live for extended periods
+    # of time.
+    class CacheStore < AbstractStore
+      # Create a new store. The cache to use can be passed in the <tt>:cache</tt> option. If it is
+      # not specified, <tt>Rails.cache</tt> will be used.
+      def initialize(app, options = {})
+        @cache = options[:cache] || Rails.cache
+        options[:expire_after] ||= @cache.options[:expires_in]
+        super
+      end
+
+      # Get a session from the cache.
+      def get_session(env, sid)
+        sid ||= generate_sid
+        session = @cache.read(cache_key(sid))
+        session ||= {}
+        [sid, session]
+      end
+
+      # Set a session in the cache.
+      def set_session(env, sid, session, options)
+        key = cache_key(sid)
+        if session
+          @cache.write(key, session, :expires_in => options[:expire_after])
+        else
+          @cache.delete(key)
+        end
+        sid
+      end
+
+      # Remove a session from the cache.
+      def destroy_session(env, sid, options)
+        @cache.delete(cache_key(sid))
+        generate_sid
+      end
+
+      private
+        # Turn the session id into a cache key.
+        def cache_key(sid)
+          "_session_id:#{sid}"
+        end
+    end
+  end
+end
diff --git a/actionpack/test/dispatch/session/cache_store_test.rb b/actionpack/test/dispatch/session/cache_store_test.rb
new file mode 100644
index 0000000000..73e056de23
--- /dev/null
+++ b/actionpack/test/dispatch/session/cache_store_test.rb
@@ -0,0 +1,181 @@
+require 'abstract_unit'
+
+class CacheStoreTest < ActionDispatch::IntegrationTest
+  class TestController < ActionController::Base
+    def no_session_access
+      head :ok
+    end
+
+    def set_session_value
+      session[:foo] = "bar"
+      head :ok
+    end
+
+    def set_serialized_session_value
+      session[:foo] = SessionAutoloadTest::Foo.new
+      head :ok
+    end
+
+    def get_session_value
+      render :text => "foo: #{session[:foo].inspect}"
+    end
+
+    def get_session_id
+      render :text => "#{request.session_options[:id]}"
+    end
+
+    def call_reset_session
+      session[:bar]
+      reset_session
+      session[:bar] = "baz"
+      head :ok
+    end
+
+    def rescue_action(e) raise end
+  end
+
+  def test_setting_and_getting_session_value
+    with_test_route_set do
+      get '/set_session_value'
+      assert_response :success
+      assert cookies['_session_id']
+
+      get '/get_session_value'
+      assert_response :success
+      assert_equal 'foo: "bar"', response.body
+    end
+  end
+
+  def test_getting_nil_session_value
+    with_test_route_set do
+      get '/get_session_value'
+      assert_response :success
+      assert_equal 'foo: nil', response.body
+    end
+  end
+
+  def test_getting_session_value_after_session_reset
+    with_test_route_set do
+      get '/set_session_value'
+      assert_response :success
+      assert cookies['_session_id']
+      session_cookie = cookies.send(:hash_for)['_session_id']
+
+      get '/call_reset_session'
+      assert_response :success
+      assert_not_equal [], headers['Set-Cookie']
+
+      cookies << session_cookie # replace our new session_id with our old, pre-reset session_id
+
+      get '/get_session_value'
+      assert_response :success
+      assert_equal 'foo: nil', response.body, "data for this session should have been obliterated from cache"
+    end
+  end
+
+  def test_getting_from_nonexistent_session
+    with_test_route_set do
+      get '/get_session_value'
+      assert_response :success
+      assert_equal 'foo: nil', response.body
+      assert_nil cookies['_session_id'], "should only create session on write, not read"
+    end
+  end
+
+  def test_setting_session_value_after_session_reset
+    with_test_route_set do
+      get '/set_session_value'
+      assert_response :success
+      assert cookies['_session_id']
+      session_id = cookies['_session_id']
+
+      get '/call_reset_session'
+      assert_response :success
+      assert_not_equal [], headers['Set-Cookie']
+
+      get '/get_session_value'
+      assert_response :success
+      assert_equal 'foo: nil', response.body
+
+      get '/get_session_id'
+      assert_response :success
+      assert_not_equal session_id, response.body
+    end
+  end
+
+  def test_getting_session_id
+    with_test_route_set do
+      get '/set_session_value'
+      assert_response :success
+      assert cookies['_session_id']
+      session_id = cookies['_session_id']
+
+      get '/get_session_id'
+      assert_response :success
+      assert_equal session_id, response.body, "should be able to read session id without accessing the session hash"
+    end
+  end
+
+  def test_deserializes_unloaded_class
+    with_test_route_set do
+      with_autoload_path "session_autoload_test" do
+        get '/set_serialized_session_value'
+        assert_response :success
+        assert cookies['_session_id']
+      end
+      with_autoload_path "session_autoload_test" do
+        get '/get_session_id'
+        assert_response :success
+      end
+      with_autoload_path "session_autoload_test" do
+        get '/get_session_value'
+        assert_response :success
+        assert_equal 'foo: #<SessionAutoloadTest::Foo bar:"baz">', response.body, "should auto-load unloaded class"
+      end
+    end
+  end
+
+  def test_doesnt_write_session_cookie_if_session_id_is_already_exists
+    with_test_route_set do
+      get '/set_session_value'
+      assert_response :success
+      assert cookies['_session_id']
+
+      get '/get_session_value'
+      assert_response :success
+      assert_equal nil, headers['Set-Cookie'], "should not resend the cookie again if session_id cookie is already exists"
+    end
+  end
+
+  def test_prevents_session_fixation
+    with_test_route_set do
+      get '/get_session_value'
+      assert_response :success
+      assert_equal 'foo: nil', response.body
+      session_id = cookies['_session_id']
+
+      reset!
+
+      get '/set_session_value', :_session_id => session_id
+      assert_response :success
+      assert_not_equal session_id, cookies['_session_id']
+    end
+  end
+
+  private
+    def with_test_route_set
+      with_routing do |set|
+        set.draw do
+          match ':action', :to => ::CacheStoreTest::TestController
+        end
+
+        @app = self.class.build_app(set) do |middleware|
+          cache = ActiveSupport::Cache::MemoryStore.new
+          middleware.use ActionDispatch::Session::CacheStore, :key => '_session_id', :cache => cache
+          middleware.delete "ActionDispatch::ShowExceptions"
+        end
+
+        yield
+      end
+    end
+end