protect_from_forgery

request_forgery_protection.rb

def protect_from_forgery(options = {})
    self.request_forgery_protection_token ||= :authenticity_token
    prepend_before_filter :verify_authenticity_token, options
end

def verify_authenticity_token
    unless verified_request?
      logger.warn "WARNING: Can't verify CSRF token authenticity" if logger
      handle_unverified_request
    end
end