Eval in background script/ service worker

[Dhruv TechApps]

Hi ,

Is it possible to run eval function either through offscreen / sandbox in MV3 version from background script/ service worker.

I successfully implemented offscreen but unable to run EVAL code in it.

manifest.json 
https://github.com/Dhruv-Techapps/acf-extension/blob/sandbox/src/manifest.json#L46-L48

offscreen
https://github.com/Dhruv-Techapps/acf-extension/blob/sandbox/src/background/off_screen.js

communicating with background and eval
https://github.com/Dhruv-Techapps/acf-extension/blob/sandbox/src/off_screen/off_screen.js

Please do share any example also with which we can run eval function within service worker in MV3

#MV3, #serviceworker #offscreen #sandbox #eval

[wOxxOm]

I don't have an example, so here's the gist of it:

1. create an iframe inside the offscreen document that points to sandbox.html file in your extension

2. add this file to sandbox in manifest.json, https://developer.chrome.com/docs/extensions/mv3/manifest/sandbox/

3. use eval inside the iframe's scripts

4. communicate via parent.postMessage inside the iframe and frameElem.contentWindow.postMessage inside the offscreen document

[Jackie Han]

Communication flow: Service Worker ⬌ Offscreen Page ⬌ Sandbox Iframe in Offscreen Page

It's really cumbersome, but that's the only way to do it for now.

In my test, you can use a sandbox page to create an offscreen page directly:

    Service Worker ⤄ Sandboxed Offscreen Page

But there is no way to communicate with the sandbox page.

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[Nathan Mo]

Do we have any progress on this?

I believe this is a very legit use case, to be able to use wasm-eval in background script, since the changes been made to csp i have not found a way to achieve this.

Here are some proposal:

1.  chrome.offscreen.createDocument('some_sandbox_html') => Promise<MessageChannel|ContentWindowThatICanPostMsg>,  the current implementation is Promise<void> which is not very useful.

2. chrome.sandbox.run(xxx) => one-time result

3. chrome.sandbox.start(xxx) => long-running sandbox with a channel to communicate

[Oliver Dunk]

Hi Nathan,

You should actually be able to use WASM in a background service worker directly.

We have some sample code for that here: https://github.com/GoogleChrome/chrome-extensions-samples/tree/main/functional-samples/cookbook.wasm-helloworld-print

Let me know how you get on!

Oliver Dunk | DevRel, Chrome Extensions | https://developer.chrome.com/ | London, GB

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/chromium-extensions/8dcb4b5b-b479-4e2f-a860-705668ae5484n%40chromium.org.