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module ActionController #:nodoc:
class InvalidToken < ActionControllerError; end
# Protect a controller's actions with the #verify_token method. Failure to validate will result in a ActionController::InvalidToken
# exception. Customize the error message through the use of rescue_templates and rescue_action_in_public.
#
# class FooController < ApplicationController
# # uses the cookie session store
# verify_token :except => :index
#
# # uses one of the other session stores that uses a session_id value.
# verify_token :secret => 'my-little-pony', :except => :index
# end
#
# Valid Options:
#
# * <tt>:only/:except</tt> - passed to the before_filter call. Set which actions are verified.
# * <tt>:secret</tt> - Custom salt used to generate the form_token. Leave this off if you are using the cookie session store.
# * <tt>:digest</tt> - Message digest used for hashing. Defaults to 'SHA1'
module RequestForgeryProtection
def self.included(base)
base.class_eval do
class_inheritable_accessor :verify_token_options
self.verify_token_options = {}
helper_method :form_token
end
base.extend(ClassMethods)
end
module ClassMethods
def verify_token(options = {})
self.request_forgery_protection_token ||= :_token
before_filter :verify_request_token, :only => options.delete(:only), :except => options.delete(:except)
verify_token_options.update(options)
end
end
protected
# The actual before_filter that is used. Modify this to change how you handle unverified requests.
def verify_request_token
verified_request? || raise(ActionController::InvalidToken)
end
# Returns true or false if a request is verified. Checks:
#
# * is the format restricted? By default, only HTML and AJAX requests are checked.
# * is it a GET request? Gets should be safe and idempotent
# * Does the form_token match the given _token value from the params?
def verified_request?
request_forgery_protection_token.nil? || request.method == :get || !verifiable_request_format? || form_token == params[request_forgery_protection_token]
end
def verifiable_request_format?
request.format.html? || request.format.js?
end
# Sets the token value for the current session. Pass a :secret option in #verify_token to add a custom salt to the hash.
def form_token
@form_token ||= verify_token_options[:secret] ? token_from_session_id : token_from_cookie_session
end
# Generates a unique digest using the session_id and the CSRF secret.
def token_from_session_id
key = verify_token_options[:secret].respond_to?(:call) ? verify_token_options[:secret].call(@session) : verify_token_options[:secret]
digest = verify_token_options[:digest] || 'SHA1'
OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new(digest), key.to_s, session.session_id.to_s)
end
# No secret was given, so assume this is a cookie session store.
def token_from_cookie_session
session[:csrf_id] ||= CGI::Session.generate_unique_id
session.dbman.generate_digest(session[:csrf_id])
end
end
end
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