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require 'openssl'
require 'rack/request'
require 'rack/response'
require 'rack/session/abstract/id'
module Rack
module Session
# 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
# })
#
class Cookie < Abstract::ID
# Encode session cookies as Base64
class Base64
def encode(str)
[str].pack('m')
end
def decode(str)
str.unpack('m').first
end
# Encode session cookies as Marshaled Base64 data
class Marshal < Base64
def encode(str)
super(::Marshal.dump(str))
end
def decode(str)
::Marshal.load(super(str)) rescue nil
end
end
end
# Use no encoding for session cookies
class Identity
def encode(str); str; end
def decode(str); str; end
end
# Reverse string encoding. (trollface)
class Reverse
def encode(str); str.reverse; end
def decode(str); str.reverse; end
end
attr_reader :coder
def initialize(app, options={})
@secrets = options.values_at(:secret, :old_secret).compact
@coder = options[:coder] ||= Base64::Marshal.new
super(app, options.merge!(:cookie_only => true))
end
private
def load_session(env)
data = unpacked_cookie_data(env)
data = persistent_session_id!(data)
[data["session_id"], data]
end
def extract_session_id(env)
unpacked_cookie_data(env)["session_id"]
end
def unpacked_cookie_data(env)
env["rack.session.unpacked_cookie_data"] ||= begin
request = Rack::Request.new(env)
session_data = request.cookies[@key]
if @secrets.size > 0 && session_data
session_data, digest = session_data.split("--")
if session_data && digest
ok = @secrets.any? do |secret|
secret && Rack::Utils.secure_compare(digest, generate_hmac(session_data, secret))
end
end
session_data = nil unless ok
end
coder.decode(session_data) || {}
end
end
def persistent_session_id!(data, sid=nil)
data ||= {}
data["session_id"] ||= sid || generate_sid
data
end
# Overwrite set cookie to bypass content equality and always stream the cookie.
def set_cookie(env, headers, cookie)
Utils.set_cookie_header!(headers, @key, cookie)
end
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
def destroy_session(env, session_id, options)
# Nothing to do here, data is in the client
generate_sid unless options[:drop]
end
def generate_hmac(data, secret)
OpenSSL::HMAC.hexdigest(OpenSSL::Digest::SHA1.new, secret, data)
end
end
end
end
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