discourse/lib/middleware/discourse_public_exceptions.rb
Kelv 0d90f6e3c3
FIX: cross origin opener policy should apply to public error responses (#31559)
In some error paths, headers that were set earlier can get overwritten
(e.g. `Cross-Origin-Opener-Policy`) by middleware such as
ActionDispatch::ShowExceptions.

This PR sets the `Cross-Origin-Opener-Policy` header to the value of the
SiteSetting `cross_origin_opener_policy_header` if it's missing and if
the response is for HTML.

In future, this DefaultHeaders middleware can be used to set other
default headers that relate to security or other purposes.

### Testing
<img width="631" alt="test"
src="https://github.com/user-attachments/assets/05106a40-2bc7-435d-91a2-4dd2a098f349"
/>
2025-03-03 17:04:24 +08:00

87 lines
2.9 KiB
Ruby

# frozen_string_literal: true
# since all the rescue from clauses are not caught by the application controller for matches
# we need to handle certain exceptions here
module Middleware
class DiscoursePublicExceptions < ::ActionDispatch::PublicExceptions
require "middleware/default_headers"
# These middlewares will be re-run when the exception response is generated
EXCEPTION_RESPONSE_MIDDLEWARES = [
ContentSecurityPolicy::Middleware,
Middleware::CspScriptNonceInjector,
]
INVALID_REQUEST_ERRORS =
Set.new(
[
Rack::QueryParser::InvalidParameterError,
ActionController::BadRequest,
ActionDispatch::Http::Parameters::ParseError,
ActionController::RoutingError,
],
)
def call(env)
# this is so so gnarly
# sometimes we leak out exceptions prior to creating a controller instance
# this can happen if we have an exception in a route constraint in some cases
# this code re-dispatches the exception to our application controller so we can
# properly translate the exception to a page
exception = env["action_dispatch.exception"]
response = ActionDispatch::Response.new
exception = nil if INVALID_REQUEST_ERRORS.include?(exception)
if exception
begin
fake_controller = ApplicationController.new
fake_controller.set_response!(response)
fake_controller.request = request = ActionDispatch::Request.new(env)
# We can not re-dispatch bad mime types
begin
request.format
rescue Mime::Type::InvalidMimeType
return [
400,
{ "Cache-Control" => "private, max-age=0, must-revalidate" },
["Invalid MIME type"]
]
end
# Or badly formatted multipart requests
begin
request.POST
rescue ActionController::BadRequest => error
if error.cause.is_a?(EOFError)
return [
400,
{ "Cache-Control" => "private, max-age=0, must-revalidate" },
["Invalid request"]
]
else
raise
end
end
if ApplicationController.rescue_with_handler(exception, object: fake_controller)
body = response.body
body = [body] if String === body
rack_response = [response.status, response.headers, body]
app = lambda { |env| rack_response }
EXCEPTION_RESPONSE_MIDDLEWARES.each { |middleware| app = middleware.new(app) }
return app.call(env)
end
rescue => e
return super if INVALID_REQUEST_ERRORS.include?(e.class)
Discourse.warn_exception(
e,
message: "Failed to handle exception in exception app middleware",
)
end
end
super
end
end
end