This cookie-based session store is the Rails default. Sessions typically contain at most a user_id and flash message; both fit within the 4K cookie size limit. Cookie-based sessions are dramatically faster than the alternatives.
If you have more than 4K of session data or don‘t want your data to be visible to the user, pick another session store.
CookieOverflow is raised if you attempt to store more than 4K of data.
A message digest is included with the cookie to ensure data integrity: a user cannot alter his user_id without knowing the secret key included in the hash. New apps are generated with a pregenerated secret in config/environment.rb. Set your own for old apps you‘re upgrading.
Session options:
- :secret: An application-wide key string or block returning a
string called per generated digest. The block is called with the
CGI::Session instance as an argument. It‘s important that the secret
is not vulnerable to a dictionary attack. Therefore, you should choose a
secret consisting of random numbers and letters and more than 30
characters. Examples:
:secret => '449fe2e7daee471bffae2fd8dc02313d' :secret => Proc.new { User.current_user.secret_key } - :digest: The message digest algorithm used to verify session integrity defaults to ‘SHA1’ but may be any digest provided by OpenSSL, such as ‘MD5’, ‘RIPEMD160’, ‘SHA256’, etc.
To generate a secret key for an existing application, run "rake secret" and set the key in config/environment.rb.
Note that changing digest or secret invalidates all existing sessions!
| MAX | = | 4096 |
| Cookies can typically store 4096 bytes. | ||
| SECRET_MIN_LENGTH | = | 30 |
| DEFAULT_OPTIONS | = | { :key => '_session_id', :domain => nil, :path => "/", :expire_after => nil, :httponly => true |
| ENV_SESSION_KEY | = | "rack.session".freeze |
| ENV_SESSION_OPTIONS_KEY | = | "rack.session.options".freeze |
| HTTP_SET_COOKIE | = | "Set-Cookie".freeze |
[ show source ]
# File actionpack/lib/action_controller/session/cookie_store.rb, line 58
58: def initialize(app, options = {})
59: # Process legacy CGI options
60: options = options.symbolize_keys
61: if options.has_key?(:session_path)
62: ActiveSupport::Deprecation.warn "Giving :session_path to SessionStore is deprecated, " <<
63: "please use :path instead", caller
64: options[:path] = options.delete(:session_path)
65: end
66: if options.has_key?(:session_key)
67: ActiveSupport::Deprecation.warn "Giving :session_key to SessionStore is deprecated, " <<
68: "please use :key instead", caller
69: options[:key] = options.delete(:session_key)
70: end
71: if options.has_key?(:session_http_only)
72: ActiveSupport::Deprecation.warn "Giving :session_http_only to SessionStore is deprecated, " <<
73: "please use :httponly instead", caller
74: options[:httponly] = options.delete(:session_http_only)
75: end
76:
77: @app = app
78:
79: # The session_key option is required.
80: ensure_session_key(options[:key])
81: @key = options.delete(:key).freeze
82:
83: # The secret option is required.
84: ensure_secret_secure(options[:secret])
85: @secret = options.delete(:secret).freeze
86:
87: @digest = options.delete(:digest) || 'SHA1'
88: @verifier = verifier_for(@secret, @digest)
89:
90: @default_options = DEFAULT_OPTIONS.merge(options).freeze
91:
92: freeze
93: end
[ show source ]
# File actionpack/lib/action_controller/session/cookie_store.rb, line 95
95: def call(env)
96: env[ENV_SESSION_KEY] = AbstractStore::SessionHash.new(self, env)
97: env[ENV_SESSION_OPTIONS_KEY] = @default_options.dup
98:
99: status, headers, body = @app.call(env)
100:
101: session_data = env[ENV_SESSION_KEY]
102: options = env[ENV_SESSION_OPTIONS_KEY]
103:
104: if !session_data.is_a?(AbstractStore::SessionHash) || session_data.send(:loaded?) || options[:expire_after]
105: session_data.send(:load!) if session_data.is_a?(AbstractStore::SessionHash) && !session_data.send(:loaded?)
106: session_data = marshal(session_data.to_hash)
107:
108: raise CookieOverflow if session_data.size > MAX
109:
110: cookie = Hash.new
111: cookie[:value] = session_data
112: unless options[:expire_after].nil?
113: cookie[:expires] = Time.now + options[:expire_after]
114: end
115:
116: cookie = build_cookie(@key, cookie.merge(options))
117: unless headers[HTTP_SET_COOKIE].blank?
118: headers[HTTP_SET_COOKIE] << "\n#{cookie}"
119: else
120: headers[HTTP_SET_COOKIE] = cookie
121: end
122: end
123:
124: [status, headers, body]
125: end