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# frozen_string_literal: true
module ActionController
module Redirecting
extend ActiveSupport::Concern
include AbstractController::Logger
include ActionController::UrlFor
ILLEGAL_HEADER_VALUE_REGEX = /[\x00-\x08\x0A-\x1F]/.freeze
class UnsafeRedirectError < StandardError; end
# Redirects the browser to the target specified in +options+. This parameter can be any one of:
#
# * <tt>Hash</tt> - The URL will be generated by calling url_for with the +options+.
# * <tt>Record</tt> - The URL will be generated by calling url_for with the +options+, which will reference a named URL for that record.
# * <tt>String</tt> starting with <tt>protocol://</tt> (like <tt>http://</tt>) or a protocol relative reference (like <tt>//</tt>) - Is passed straight through as the target for redirection.
# * <tt>String</tt> not containing a protocol - The current protocol and host is prepended to the string.
# * <tt>Proc</tt> - A block that will be executed in the controller's context. Should return any option accepted by +redirect_to+.
#
# === Examples:
#
# redirect_to action: "show", id: 5
# redirect_to @post
# redirect_to "http://www.rubyonrails.org"
# redirect_to "/images/screenshot.jpg"
# redirect_to posts_url
# redirect_to proc { edit_post_url(@post) }
#
# The redirection happens as a <tt>302 Found</tt> header unless otherwise specified using the <tt>:status</tt> option:
#
# redirect_to post_url(@post), status: :found
# redirect_to action: 'atom', status: :moved_permanently
# redirect_to post_url(@post), status: 301
# redirect_to action: 'atom', status: 302
#
# The status code can either be a standard {HTTP Status code}[https://www.iana.org/assignments/http-status-codes] as an
# integer, or a symbol representing the downcased, underscored and symbolized description.
# Note that the status code must be a 3xx HTTP code, or redirection will not occur.
#
# If you are using XHR requests other than GET or POST and redirecting after the
# request then some browsers will follow the redirect using the original request
# method. This may lead to undesirable behavior such as a double DELETE. To work
# around this you can return a <tt>303 See Other</tt> status code which will be
# followed using a GET request.
#
# redirect_to posts_url, status: :see_other
# redirect_to action: 'index', status: 303
#
# It is also possible to assign a flash message as part of the redirection. There are two special accessors for the commonly used flash names
# +alert+ and +notice+ as well as a general purpose +flash+ bucket.
#
# redirect_to post_url(@post), alert: "Watch it, mister!"
# redirect_to post_url(@post), status: :found, notice: "Pay attention to the road"
# redirect_to post_url(@post), status: 301, flash: { updated_post_id: @post.id }
# redirect_to({ action: 'atom' }, alert: "Something serious happened")
#
# Statements after +redirect_to+ in our controller get executed, so +redirect_to+ doesn't stop the execution of the function.
# To terminate the execution of the function immediately after the +redirect_to+, use return.
# redirect_to post_url(@post) and return
def redirect_to(options = {}, response_options = {})
raise ActionControllerError.new("Cannot redirect to nil!") unless options
raise AbstractController::DoubleRenderError if response_body
self.status = _extract_redirect_to_status(options, response_options)
redirect_to_location = _compute_redirect_to_location(request, options)
_ensure_url_is_http_header_safe(redirect_to_location)
self.location = redirect_to_location
self.response_body = "<html><body>You are being <a href=\"#{ERB::Util.unwrapped_html_escape(response.location)}\">redirected</a>.</body></html>"
end
# Redirects the browser to the page that issued the request (the referrer)
# if possible, otherwise redirects to the provided default fallback
# location.
#
# The referrer information is pulled from the HTTP +Referer+ (sic) header on
# the request. This is an optional header and its presence on the request is
# subject to browser security settings and user preferences. If the request
# is missing this header, the <tt>fallback_location</tt> will be used.
#
# redirect_back fallback_location: { action: "show", id: 5 }
# redirect_back fallback_location: @post
# redirect_back fallback_location: "http://www.rubyonrails.org"
# redirect_back fallback_location: "/images/screenshot.jpg"
# redirect_back fallback_location: posts_url
# redirect_back fallback_location: proc { edit_post_url(@post) }
# redirect_back fallback_location: '/', allow_other_host: false
#
# ==== Options
# * <tt>:fallback_location</tt> - The default fallback location that will be used on missing +Referer+ header.
# * <tt>:allow_other_host</tt> - Allow or disallow redirection to the host that is different to the current host, defaults to true.
#
# All other options that can be passed to #redirect_to are accepted as
# options and the behavior is identical.
def redirect_back(fallback_location:, allow_other_host: true, **args)
referer = request.headers["Referer"]
redirect_to_referer = referer && (allow_other_host || _url_host_allowed?(referer))
redirect_to redirect_to_referer ? referer : fallback_location, **args
end
def _compute_redirect_to_location(request, options) #:nodoc:
case options
# The scheme name consist of a letter followed by any combination of
# letters, digits, and the plus ("+"), period ("."), or hyphen ("-")
# characters; and is terminated by a colon (":").
# See https://tools.ietf.org/html/rfc3986#section-3.1
# The protocol relative scheme starts with a double slash "//".
when /\A([a-z][a-z\d\-+\.]*:|\/\/).*/i
options
when String
request.protocol + request.host_with_port + options
when Proc
_compute_redirect_to_location request, instance_eval(&options)
else
url_for(options)
end.delete("\0\r\n")
end
module_function :_compute_redirect_to_location
public :_compute_redirect_to_location
private
def _extract_redirect_to_status(options, response_options)
if options.is_a?(Hash) && options.key?(:status)
Rack::Utils.status_code(options.delete(:status))
elsif response_options.key?(:status)
Rack::Utils.status_code(response_options[:status])
else
302
end
end
def _url_host_allowed?(url)
URI(url.to_s).host == request.host
rescue ArgumentError, URI::Error
false
end
def _ensure_url_is_http_header_safe(url)
# Attempt to comply with the set of valid token characters
# defined for an HTTP header value in
# https://datatracker.ietf.org/doc/html/rfc7230#section-3.2.6
if url.match(ILLEGAL_HEADER_VALUE_REGEX)
msg = "The redirect URL #{url} contains one or more illegal HTTP header field character. " \
"Set of legal characters defined in https://datatracker.ietf.org/doc/html/rfc7230#section-3.2.6"
raise UnsafeRedirectError, msg
end
end
end
end
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