Websockets, cross domain requests and content script?

Add-ons Development
1

I am developping a content script which opens a websocket to our backend.

"permissions": {
    "cross-domain-content": ["http://localhost:3000"]
}

This code allows me to request my backend through HTTP, but my websocket is still blocked by the content security policy. I tried several combinaisons and workaround to add ws://localhost:3000 to that list but nothing worked. Since this webpage makes no mention of websockets support, I start to wonder if there is a way do that.

2

I also encounter this issue.
Just created a Stackoverflow ticket for it:
http://stackoverflow.com/questions/36835030/firefox-add-on-sdk-extension-with-websocket-doesnt-work-for-facebook-twitter

In wikipedia (https://en.wikipedia.org/wiki/Content_Security_Policy), it even says that Addon should be exempted from CSP. But this turns out not to be the case for Firefox.
In Chrome, however, I can make things work. The websocket open inside Facebook.com, who implements CSP, to my localhost works fine. But in Firefox it doesn’t.
So I suppose this is an issue for Firefox.

3

In the meantime, I used socket.io in long polling mode. It worked.

4

Thanks for sharing that workaround. It’s been awhile though we should try to get this on bugzilla and fixed if it hasn’t been yet.

5

As I commented in the SO topic, using page-worker is another workaround so you can still use proper WebSockets. It’d be worth testing if this also happens for web-ext.