--- /dev/null
+require 'cgi'
+require 'cgi/session'
+require 'openssl' # to generate the HMAC message digest
+
+# 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.
+# TamperedWithCookie is raised if the data integrity check fails.
+#
+# 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:
+#
+# * <tt>:secret</tt>: 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 }
+#
+# * <tt>:digest</tt>: 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!
+class CGI::Session::CookieStore
+ # Cookies can typically store 4096 bytes.
+ MAX = 4096
+ SECRET_MIN_LENGTH = 30 # characters
+
+ # Raised when storing more than 4K of session data.
+ class CookieOverflow < StandardError; end
+
+ # Raised when the cookie fails its integrity check.
+ class TamperedWithCookie < StandardError; end
+
+ # Called from CGI::Session only.
+ def initialize(session, options = {})
+ # The session_key option is required.
+ if options['session_key'].blank?
+ raise ArgumentError, 'A session_key is required to write a cookie containing the session data. Use config.action_controller.session = { :session_key => "_myapp_session", :secret => "some secret phrase" } in config/environment.rb'
+ end
+
+ # The secret option is required.
+ ensure_secret_secure(options['secret'])
+
+ # Keep the session and its secret on hand so we can read and write cookies.
+ @session, @secret = session, options['secret']
+
+ # Message digest defaults to SHA1.
+ @digest = options['digest'] || 'SHA1'
+
+ # Default cookie options derived from session settings.
+ @cookie_options = {
+ 'name' => options['session_key'],
+ 'path' => options['session_path'],
+ 'domain' => options['session_domain'],
+ 'expires' => options['session_expires'],
+ 'secure' => options['session_secure'],
+ 'http_only' => options['session_http_only']
+ }
+
+ # Set no_hidden and no_cookies since the session id is unused and we
+ # set our own data cookie.
+ options['no_hidden'] = true
+ options['no_cookies'] = true
+ end
+
+ # To prevent users from using something insecure like "Password" we make sure that the
+ # secret they've provided is at least 30 characters in length.
+ def ensure_secret_secure(secret)
+ # There's no way we can do this check if they've provided a proc for the
+ # secret.
+ return true if secret.is_a?(Proc)
+
+ if secret.blank?
+ raise ArgumentError, %Q{A secret is required to generate an integrity hash for cookie session data. Use config.action_controller.session = { :session_key => "_myapp_session", :secret => "some secret phrase of at least #{SECRET_MIN_LENGTH} characters" } in config/environment.rb}
+ end
+
+ if secret.length < SECRET_MIN_LENGTH
+ raise ArgumentError, %Q{Secret should be something secure, like "#{CGI::Session.generate_unique_id}". The value you provided, "#{secret}", is shorter than the minimum length of #{SECRET_MIN_LENGTH} characters}
+ end
+ end
+
+ # Restore session data from the cookie.
+ def restore
+ @original = read_cookie
+ @data = unmarshal(@original) || {}
+ end
+
+ # Wait until close to write the session data cookie.
+ def update; end
+
+ # Write the session data cookie if it was loaded and has changed.
+ def close
+ if defined?(@data) && !@data.blank?
+ updated = marshal(@data)
+ raise CookieOverflow if updated.size > MAX
+ write_cookie('value' => updated) unless updated == @original
+ end
+ end
+
+ # Delete the session data by setting an expired cookie with no data.
+ def delete
+ @data = nil
+ clear_old_cookie_value
+ write_cookie('value' => nil, 'expires' => 1.year.ago)
+ end
+
+ # Generate the HMAC keyed message digest. Uses SHA1 by default.
+ def generate_digest(data)
+ key = @secret.respond_to?(:call) ? @secret.call(@session) : @secret
+ OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new(@digest), key, data)
+ end
+
+ private
+ # Marshal a session hash into safe cookie data. Include an integrity hash.
+ def marshal(session)
+ data = ActiveSupport::Base64.encode64s(Marshal.dump(session))
+ "#{data}--#{generate_digest(data)}"
+ end
+
+ # Unmarshal cookie data to a hash and verify its integrity.
+ def unmarshal(cookie)
+ if cookie
+ data, digest = cookie.split('--')
+
+ # Do two checks to transparently support old double-escaped data.
+ unless digest == generate_digest(data) || digest == generate_digest(data = CGI.unescape(data))
+ delete
+ raise TamperedWithCookie
+ end
+
+ Marshal.load(ActiveSupport::Base64.decode64(data))
+ end
+ end
+
+ # Read the session data cookie.
+ def read_cookie
+ @session.cgi.cookies[@cookie_options['name']].first
+ end
+
+ # CGI likes to make you hack.
+ def write_cookie(options)
+ cookie = CGI::Cookie.new(@cookie_options.merge(options))
+ @session.cgi.send :instance_variable_set, '@output_cookies', [cookie]
+ end
+
+ # Clear cookie value so subsequent new_session doesn't reload old data.
+ def clear_old_cookie_value
+ @session.cgi.cookies[@cookie_options['name']].clear
+ end
+end
projects / depot.git / blobdiff