Supply credentials for proxy authorization in MV3

[erba2061]

Issue https://bugs.chromium.org/p/chromium/issues/detail?id=1135492

Suggestions

• Declarative authCredentials property in ProxyServer config
  • Firefox supports similar implementation with proxyAuthorizationHeader in ProxyInfo
• Allow to modify/add Proxy-Authorization header on CONNECT requests
  • https://bugs.chromium.org/p/chromium/issues/detail?id=1352397
  • https://bugs.chromium.org/p/chromium/issues/detail?id=129572

Background

Blocking webRequest API will not be supported in favour of DNR API. Adding blocking webRequest.onAuthRequired listener is the only way to supply credentials for proxy servers in Chromium browsers.

Note that browser sign-in dialog box (asks user to enter proxy credentials) is not sufficient:

• User does not know which credentials he/she should enter. Proxy server authorization credentials are usually different from account credentials used to login to use extension features
• Proxy returns 407 (Proxy Authentication Required) more than once during browsing time, causing dialogs to popup at random times

Impact

Privacy extensions won't be able to provide proxy services to users without consistent authorization solution in MV3.

[olso]

Have the same issue

[erosman]

There could be an alternative approach to proxy authentication in MV3 without webRequest.onAuthRequired, by using DNR.

Currently DNR can not be applied to proxy. If it would be possible to apply to proxy then, a set of rules can be created using declarativeNetRequest.updateDynamicRules to pass authentication to the proxy.

Scenario: Browser -> proxyurl.com -> target.com
It appears that the urlFilter applies to the target.com.

const removeRuleIds = [1];
const addRules = [
  {
    id: 1,
    priority: 1,
    action: {
      type: 'modifyHeaders',
      responseHeaders: [
        {
          header: 'Proxy-Authorization',
          operation: 'set',
          value: 'Basic ' + btoa(username + ':' + password)
        }
      ]
    },
    condition: {urlFilter: '||proxyurl.com'}
  }
];

chrome.declarativeNetRequest.updateDynamicRules({removeRuleIds, addRules});

Also: Issue 1318138: Add headers using declarativeNetRequest only if the request is being proxied

[erosman]

Chrome seems to have introduced a new permission webRequestAuthProvider

ref:
https://groups.google.com/a/chromium.org/g/extensions-reviews/c/WEtDeiGxbuM
https://bugs.chromium.org/p/chromium/issues/detail?id=1135492

It appears to have been pushed for v108 in Chrome (Stable Release Tue, Nov 29, 2022)