class Rack::Protection::AuthenticityToken

Compatible with Rails and rack-csrf.
included in the session.
Only accepts unsafe HTTP requests if a given access token matches the token
More infos
en.wikipedia.org/wiki/Cross-site_request_forgery<br>Supported browsers
all
Prevented attack

CSRF
#

def accepts?(env) 

def accepts?(env)
  return true if safe? env
  session = session env
  token   = session[:csrf] ||= session['_csrf_token'] || random_string
  env['HTTP_X_CSRF_TOKEN'] == token or
    Request.new(env).params['authenticity_token'] == token
end