Container proxy settings seem to use 'global' Firefox proxy settings for exceptions

[LukeDRussell]

If I have any settings in "No proxy for", this seems to pass through to the container's proxy.

I would personally like to be able to set 'No proxy for' for each container. Maybe it's possible now, but I can't see how.

[kgeminicdev]

That's Firefox, not the extension. MAC's proxy handler doesn't look at the URL at all, it just returns the container's proxy for every request from a tab in that container:

multi-account-containers/src/js/background/assignManager.js

Lines 205 to 229 in b2dc360

	async handleProxifiedRequest(requestInfo) {
	// The following blocks potentially dangerous requests for privacy that come without a tabId
	if(requestInfo.tabId === -1) {
	return {};
	}
	const tab = await browser.tabs.get(requestInfo.tabId);
	const result = await proxifiedContainers.retrieve(tab.cookieStoreId);
	if (!result || !result.proxy) {
	return {};
	}
	// proxyDNS only works for SOCKS proxies
	if (["socks", "socks4"].includes(result.proxy.type)) {
	result.proxy.proxyDNS = true;
	}
	if (!result.proxy.mozProxyEnabled) {
	return result.proxy;
	}
	// Let's add the isolation key.
	return [{ ...result.proxy, connectionIsolationKey: "" + MozillaVPN_Background.isolationKey }];
	},

Firefox then runs one more check on whatever an extension's proxy.onRequest returned, and drops the proxy if the host matches network.proxy.no_proxies_on, which is the "No proxy for" box: https://github.com/mozilla-firefox/firefox/blob/59c8a945f229e17d78d091d82f1624494e2c5006/netwerk/base/nsProtocolProxyService.cpp#L129-L139

That pref is read regardless of which proxy mode you've picked, so it still applies when the global setting is "No proxy" and the box is greyed out.

So per-container "No proxy for" isn't possible right now. The extension would have to support it by checking the URL in that handler, and even then it could only add exceptions on top of the global list, not remove ones Firefox enforces.

What you can do today is clear network.proxy.no_proxies_on in about:config so container proxies apply everywhere, and open the sites you want direct in a container without a proxy. Loopback addresses are still never proxied unless you set network.proxy.allow_hijacking_localhost.

[LukeDRussell]

Thank you for the detailed response.

I'd like this considered as a feature request then:

• Optional, per container, allow a container to have it's own, distinct "No proxy for" list, that doesn't inherit from network.proxy.no_proxies_on