class Rack::Session::Cookie

Rack::Session::Cookie provides simple cookie based session management. By default, the session is a Ruby Hash stored as base64 encoded marshalled data set to :key (default: rack.session). The object that encodes the session data is configurable and must respond to encode and decode. Both methods must take a string and return a string.

When the secret key is set, cookie data is checked for data integrity. The old secret key is also accepted and allows graceful secret rotation.

Example:

use Rack::Session::Cookie, :key => 'rack.session',
                           :domain => 'foo.com',
                           :path => '/',
                           :expire_after => 2592000,
                           :secret => 'change_me',
                           :old_secret => 'also_change_me'

All parameters are optional.

Example of a cookie with no encoding:

Rack::Session::Cookie.new(application, {
  :coder => Rack::Session::Cookie::Identity.new
})

Example of a cookie with custom encoding:

Rack::Session::Cookie.new(application, {
  :coder => Class.new {
    def encode(str); str.reverse; end
    def decode(str); str.reverse; end
  }.new
})

Attributes

coder[R]

Public Class Methods

new(app, options={}) click to toggle source
Calls superclass method Rack::Session::Abstract::ID.new
# File lib/rack/session/cookie.rb, line 83
      def initialize(app, options={})
        @secrets = options.values_at(:secret, :old_secret).compact
        warn "        SECURITY WARNING: No secret option provided to Rack::Session::Cookie.
        This poses a security threat. It is strongly recommended that you
        provide a secret to prevent exploits that may be possible from crafted
        cookies. This will not be supported in future versions of Rack, and
        future versions will even invalidate your existing user cookies.

        Called from: #{caller[0]}.
" unless @secrets.size >= 1
        @coder  = options[:coder] ||= Base64::Marshal.new
        super(app, options.merge!(:cookie_only => true))
      end

Private Instance Methods

destroy_session(env, session_id, options) click to toggle source
# File lib/rack/session/cookie.rb, line 159
def destroy_session(env, session_id, options)
  # Nothing to do here, data is in the client
  generate_sid unless options[:drop]
end
extract_session_id(env) click to toggle source
# File lib/rack/session/cookie.rb, line 106
def extract_session_id(env)
  unpacked_cookie_data(env)["session_id"]
end
generate_hmac(data, secret) click to toggle source
# File lib/rack/session/cookie.rb, line 164
def generate_hmac(data, secret)
  OpenSSL::HMAC.hexdigest(OpenSSL::Digest::SHA1.new, secret, data)
end
load_session(env) click to toggle source
# File lib/rack/session/cookie.rb, line 100
def load_session(env)
  data = unpacked_cookie_data(env)
  data = persistent_session_id!(data)
  [data["session_id"], data]
end
persistent_session_id!(data, sid=nil) click to toggle source
# File lib/rack/session/cookie.rb, line 131
def persistent_session_id!(data, sid=nil)
  data ||= {}
  data["session_id"] ||= sid || generate_sid
  data
end
set_session(env, session_id, session, options) click to toggle source
# File lib/rack/session/cookie.rb, line 143
def set_session(env, session_id, session, options)
  session = session.merge("session_id" => session_id)
  session_data = coder.encode(session)

  if @secrets.first
    session_data = "#{session_data}--#{generate_hmac(session_data, @secrets.first)}"
  end

  if session_data.size > (4096 - @key.size)
    env["rack.errors"].puts("Warning! Rack::Session::Cookie data size exceeds 4K.")
    nil
  else
    session_data
  end
end