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require 'active_support/core_ext/class/attribute'
module ActionController #:nodoc:
class InvalidAuthenticityToken < ActionControllerError #:nodoc:
end
# Controller actions are protected from Cross-Site Request Forgery (CSRF) attacks
# by including a token in the rendered html for your application. This token is
# stored as a random string in the session, to which an attacker does not have
# access. When a request reaches your application, \Rails then verifies the received
# token with the token in the session. Only HTML and javascript requests are checked,
# so this will not protect your XML API (presumably you'll have a different
# authentication scheme there anyway). Also, GET requests are not protected as these
# should be idempotent.
#
# CSRF protection is turned on with the <tt>protect_from_forgery</tt> method,
# which will check the token and raise an ActionController::InvalidAuthenticityToken
# if it doesn't match what was expected. A call to this method is generated for new
# \Rails applications by default. You can customize the error message by editing
# public/422.html.
#
# The token parameter is named <tt>authenticity_token</tt> by default. The name and
# value of this token must be added to every layout that renders forms by including
# <tt>csrf_meta_tags</tt> in the html +head+.
#
# Learn more about CSRF attacks and securing your application in the
# {Ruby on Rails Security Guide}[http://guides.rubyonrails.org/security.html].
module RequestForgeryProtection
extend ActiveSupport::Concern
include AbstractController::Helpers
include AbstractController::Callbacks
included do
# Sets the token parameter name for RequestForgery. Calling +protect_from_forgery+
# sets it to <tt>:authenticity_token</tt> by default.
config_accessor :request_forgery_protection_token
self.request_forgery_protection_token ||= :authenticity_token
# Controls whether request forgery protection is turned on or not. Turned off by default only in test mode.
config_accessor :allow_forgery_protection
self.allow_forgery_protection = true if allow_forgery_protection.nil?
helper_method :form_authenticity_token
helper_method :protect_against_forgery?
end
module ClassMethods
# Turn on request forgery protection. Bear in mind that only non-GET, HTML/JavaScript requests are checked.
#
# Example:
#
# class FooController < ApplicationController
# protect_from_forgery :except => :index
#
# You can disable csrf protection on controller-by-controller basis:
#
# skip_before_filter :verify_authenticity_token
#
# It can also be disabled for specific controller actions:
#
# skip_before_filter :verify_authenticity_token, :except => [:create]
#
# Valid Options:
#
# * <tt>:only/:except</tt> - Passed to the <tt>before_filter</tt> call. Set which actions are verified.
def protect_from_forgery(options = {})
self.request_forgery_protection_token ||= :authenticity_token
prepend_before_filter :verify_authenticity_token, options
end
end
protected
# The actual before_filter that is used. Modify this to change how you handle unverified requests.
def verify_authenticity_token
unless verified_request?
logger.debug "WARNING: Can't verify CSRF token authenticity" if logger
handle_unverified_request
end
end
def handle_unverified_request
reset_session
end
# Returns true or false if a request is verified. Checks:
#
# * is it a GET request? Gets should be safe and idempotent
# * Does the form_authenticity_token match the given token value from the params?
# * Does the X-CSRF-Token header match the form_authenticity_token
def verified_request?
!protect_against_forgery? || request.get? ||
form_authenticity_token == params[request_forgery_protection_token] ||
form_authenticity_token == request.headers['X-CSRF-Token']
end
# Sets the token value for the current session.
def form_authenticity_token
session[:_csrf_token] ||= ActiveSupport::SecureRandom.base64(32)
end
# The form's authenticity parameter. Override to provide your own.
def form_authenticity_param
params[request_forgery_protection_token]
end
def protect_against_forgery?
allow_forgery_protection
end
end
end
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