class Rack::Protection::HttpOrigin

does not match default or whitelisted URIs.
Does not accept unsafe HTTP requests when value of Origin HTTP request header
More infos
en.wikipedia.org/wiki/Cross-site_request_forgery<br>Supported browsers
Google Chrome 2, Safari 4 and later
Prevented attack

CSRF
#

def accepts?(env) 

def accepts?(env)
  return true if safe? env
  return true unless origin = env['HTTP_ORIGIN']
  return true if base_url(env) == origin
  Array(options[:origin_whitelist]).include? origin
end

def base_url(env) 

def base_url(env)
  request = Rack::Request.new(env)
  port = ":#{request.port}" unless request.port == DEFAULT_PORTS[request.scheme]
  "#{request.scheme}://#{request.host}#{port}"
end