Ruffle Error on Tor Browsers

[VasilisThePikachu]

This error appears when you try to load anything when on the tor browser with the extension or not
Tor browsers security level was set the standard and NoScript was turned off

While this may be useless as most people won't view flash on tor browser it will be nice to have

Reproduction:
1: Start Tor browser
2: Set security level to Standard
3: Visit https://ruffle.rs/demo/

Reproduced on:
Windows 10 Tor browser 10.0.5 (based on Mozilla Firefox 78.5.0esr)
Tails OS 4.14 Tor browser 10.0.7 (based on Mozilla Firefox 78.6.0esr)

If more info is needed tell me in comments

On demo (without the extension installed):

Error Info

Error name: ReferenceError
Error message: webkitAudioContext is not defined
Error stack:

624@https://ruffle.rs/demo/662.index.js:1:15436
bi@https://ruffle.rs/demo/index.js:1:34398
662@https://ruffle.rs/demo/662.index.js:1:12310
bi@https://ruffle.rs/demo/index.js:1:34398

Player Info

Allows script access: false

Page Info

Page URL: https://ruffle.rs/demo/

Browser Info

Useragent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0
OS: Win32

Ruffle Info

Version: 0.1.0
Name: nightly 2020-12-15
Channel: nightly
Built: 2020-12-15T00:33:46.121Z
Commit: 709561a

Is web assembly allowed in the Tor browser? I would think not. based on an unrelated project here PrivateBin/PrivateBin#454 at least in 2019 Tor didn't have webasm.

[rdrpenguin04]

This doesn't look like a WASM-related issue. Tor disabled AudioContext for security reasons, as the Web Audio API is now available.

[rdrpenguin04]

Source: https://gitlab.torproject.org/legacy/trac/-/issues/12212

[VasilisThePikachu]

Seems like that was the case as enabling dom.webaudio.enabled in about:config fixes it
is there anything that can be done about this?

also, while it now can do playback it seems like you can't interact with it at all

[Herschel]

Tor can disable many features for security reasons, so I don't think Ruffle will be officially supported on Tor. But we should try to fail more gracefully in these cases (for example, in the audio context case, we could play without audio if web audio isn't available).

[LiEnby]

TOR disables alot of stuff to try prevent fingerprinting and stuff.

[Herschel]

Looked into this a bit more; the issue is that wasm-bindgen generates JS with this line:

const lAudioContext = (typeof AudioContext !== 'undefined' ? AudioContext : webkitAudioContext);

which causes an error because AudioContext/webkitAudioContext are undefined in Tor. This will take a change to wasm-bindgen to fix. Then we can catch the error normally and disable audio.

Opened wasm-bindgen/wasm-bindgen#2437 on wasm-bindgen.

[Herschel]

I've bumped to the latest wasm-bindgen, and Ruffle will now run without audio when the audio context can't be created. So Ruffle will now at least run in Tor with default settings.