DNS leaks on socks proxy

[Yoskaldyr]

• Multi-Account Containers Version: 8.0.4
• Operating System + Version: All versions
• Firefox Version: All supported versions
• Other installed Add-ons + Version + Enabled/Disabled-Status:

Actual behavior

DNS leaks exist with socks servers :(

Expected behavior

No DNS leaks

Steps to reproduce

1. Just use any socks proxy for container

Notes

It can be fixed just one line of code
in file src\js\background\assignManager.js
change

    if (!result.proxy.mozProxyEnabled) {
        return result.proxy;
    }

    // Let's add the isolation key.
    return [{ ...result.proxy, connectionIsolationKey: "" + MozillaVPN_Background.isolationKey }];

to

    if (!result.proxy.mozProxyEnabled) {
        return [{ ...result.proxy, proxyDNS: true }];
    }

    // Let's add the isolation key.
    return [{ ...result.proxy, connectionIsolationKey: "" + MozillaVPN_Background.isolationKey, proxyDNS: true }];

[groovecoder]

Thanks for the issue report. Fix in #2258.

[firefox4ever]

@groovecoder DNS leaks are still present even with proxyDNS: true when firefox proxy settings set to any value except manual proxy settings with socks proxy set and DNS over Socks enabled. Looks like firefox ignores proxyDNS flag from webextension API when global DNS over Socks setting disabled. Issue exist on latest relese version and latest esr version.

I think this is firefox webextension proxy API issue. Because DNS leaks are present in all other similar addons.

[groovecoder]

@firefox4ever - are you running this merged branch of the add-on? Or still running 8.0.4? We haven't been able to release yet.

[firefox4ever]

@groovecoder Yes, I tested latest version of main branch with latest commits using web-ext
I develop own container proxifier addon and found similar issue. And I decided to check all other addons with similar functions.
I think it firefox issue, but I'm not sure. Looks like some conflicts between firefox settings and proxy webextension api

[Lem]

As already mentioned in the other issue, this issue seems to break the "Advanced Proxy Settings" in 8.0.5.

[lxgr]

This is still (or again) happening in 8.1.2. What's strange is that Firefox somehow uses both the host and the SOCKS to resolve hostnames! Could this be some interaction with DoH fallbacks to local DNS?

Update: Aparently this is some negative interaction with uBlock! After disabling that, it only uses the SOCKS tunnel for name resolution as expected. I've raised a ticket for this here, but maybe somebody here knows whether there is actually any API for third-party extensions to detect per-container proxying, so that they can (as in uBlock's case) adapt their own network requests, or ideally have them pass through the same proxy as those of the visited site?