A script to decode the Rails _session cookie

sessiondecode.rb

#!/usr/bin/env ruby
# This interactive script decodes the _session cookie contents of the Rails
# Session Store. It can be useful when debugging session-related problems.

# Be aware that Firefox doesn't update the cookie contents on every request when
# you keep the according dialog open. If you have to debug HTTP regularly, I can
# recommend the Charles Web Debugging Proxy (http://www.charlesproxy.com/)

puts("Loading...") 
Signal.trap("INT") { puts "\n" ; exit }
require File.join(File.dirname(__FILE__), "..", "config", "environment")
# alternatively, require cgi and base64 
require "pp"
puts "Ready. Paste _session cookie contents to decode, press enter for new line, CTRL-C to exit."
session_cookie=gets

while true do
  unless session_cookie=="\n"
    puts "-" * 80
    begin
      pp Marshal.load(Base64.decode64(CGI.unescape(session_cookie).split('--').first))
    rescue ArgumentError,TypeError
      puts "ERROR: could not decode that."
    end
    puts "_" * 80
  end
  session_cookie=gets
end