'XMLHttpRequest.prototype.getResponseHeader()' issue in scriptlet and redirect

[piquark6046]

Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
• This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
• The issue is not present after disabling uBO in the browser.
• I checked the documentation to understand that the issue I am reporting is not normal behavior.

I tried to reproduce the issue when...

• uBO is the only extension.
• uBO uses default lists and settings.
• using a new, unmodified browser profile.

Description

Screencast.from.2023-03-01.14-13-33.webm

A specific URL where the issue occurs.

https://piquark6046.github.io/testpage/XMLResponseHeader/

Steps to Reproduce

The step to reproduce is attached in the video.

piquark6046.github.io##+js(no-xhr-if, adsbygoogle.js)
||pagead2.googlesyndication.com/pagead/js/adsbygoogle.js$redirect=googlesyndication_adsbygoogle.js
@@||pagead2.googlesyndication.com/pagead/js/adsbygoogle.js

Expected behavior

• XMLHttpRequest.prototype.status returns 200.
• XMLHttpRequest.prototype.getResponseHeader('content-length') returns a digit number.
• XMLHttpRequest.prototype.getResponseHeader('expires') returns a date and time.
• XMLHttpRequest.prototype.getAllResponseHeaders() returns response header of a request.

Actual behavior

When a $redirect filter is applied:

• XMLHttpRequest.prototype.status returns 0.
• XMLHttpRequest.prototype.getResponseHeader('content-length') returns anull.
• XMLHttpRequest.prototype.getResponseHeader('expires') returns null.
• XMLHttpRequest.prototype.getAllResponseHeaders() returns an empty string.

When a scriptlet filter is applied:

• All methods and property return empty data.

uBO version

1.47.2

Browser name and version

Mozilla Firefox Developer Edition 111.0b7

Operating System and version

Ubuntu 22.10

[piquark6046]

Related issues:

• Fix 'prevent-xhr' and 'trusted-replace-xhr-response' — mock getResponseHeader() and getAllResponseHeaders() methods AdguardTeam/Scriptlets#295
• tsuvod.com AdguardTeam/AdguardFilters#144062

[JobcenterTycoon]

Similar: uBlockOrigin/uAssets#16430 (comment)

[gorhill]

Probably because on Firefox xhr requests are redirected using data: URI.

---

Also, please transcribe here the filter to use for your repro case.

[piquark6046]

Added into Steps to Reproduce.

[piquark6046]

I think that uBO on a chromium-based web browser ¹ is also affected.

Footnotes

1. Brave 1.48.171 ↩

[gorhill]

I get exceptions being raised. Probably should move your <script> tag just before </body>.

[uBlock-user]

All methods and property return empty data.

A redirect only loads a specific resource, nothing else, thats always been the case with any redirect and not limited to xhr only.

[gorhill]

I want to go through repro steps, but your test case has an issue, your script references elements in the DOM which may not be there yet. If you move your script tag at the end of the body, the repro case will work without throwing an exception.

[piquark6046]

Fixed.

[MasterKia]

Similar (the site uses response.status as bait):
https://github.com/uBlockOrigin/uAssets/issues/14204

        let src = '[Some URL]';
        const controller = new AbortController();
        const timeout = setTimeout(() => controller.abort(), 10_000);
        let response;
        try {
            response = await fetch(src, {signal: controller.signal});
        }
        if (response.status !== 200) {
            this.#showFail();
            return;
        }

[MasterKia]

Isn't the behavior shown in the this thread by design?

https://github.com/uBlockOrigin/uBlock-issues/wiki/Resources-Library#no-fetch-ifjs- & https://github.com/uBlockOrigin/uBlock-issues/wiki/Resources-Library#no-xhr-ifjs-:

returning a promise which always resolve to an empty response.

---

Anyway, AdGuard's fix:
AdguardTeam/Scriptlets@531ea12#diff-ff559a075c8491c9b6a0cdeea5aceee74950e68eb2423435ab3afaa87c4452ccR28

[JobcenterTycoon]

gorhill/uBlock@418087d

[ghajini]

@gorhill
are you planning to support no-fetch-if to return actual response?
this is required for case here
uBlockOrigin/uAssets#19295

firefox

[piquark6046]

@ghajini #2526
Did you mean this issue?

[ghajini]

yes for no-fetch-if

[uBlock-user]

What was done for no-xhr-if in gorhill/uBlock@bf591d9 needs to be done for no-fetch-if.

[gwarser]

'expires'?

[uBlock-user]

'expires' was not added or is missing..

[gorhill]

Adding expires is too arbitrary, it's not always there. I would want to see many real cases before I start to consider throwing in there arbitrary headers.

[JobcenterTycoon]

@gorhill will the Resources-Library get a update? The latest features like length: are missing.

[MasterKia]

I can update the wiki in a week or so.

[JobcenterTycoon]

Still not updated