Felipe Erias talks about Igalia's work toward improving chromium's Declarative Net Request rules proposed for Manifest V3 (c) BlinkOn 16 Virtual Event, May 18 - 19, 2022 https://www.chromium.org/events/blinkon-16/

1. Finer control of DNR rules
Felipe Erias
BlinkOn 16 — May 2022
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2. Hello!
Felipe Erias
felipeerias in GitHub, Twitter
felipeerias@igalia.com
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3. Web Extensions: manifest V3
Privacy: less need to access user data
Security: stricter protocols and requirements
Performance
Follow the Web Platform way of doing things
Keep the platform capable and valuable for users
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4. Declarative Net Request
Provide control over network requests (including
blocking resources)
Previously: network requests are intercepted and
evaluated in the extension process
Now: extension declares a set of rules that the
browser uses to evaluate and modify requests
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5. Rule resources (1)
Static lists of rules are bundled with the extension
Can only be modified by updating the extension
Enabled and disabled as a whole
Limits: 10 enabled lists, up to 30,000 rules
// Enable ruleset with id "myRules"
chrome.declarativeNetRequest.updateEnabledRulesets(
{
disableRulesetIds: ["unusedList"],
enableRulesetIds: ["myRules"]
}
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6. Rule resources (2)
Dynamic rules
Can be added and removed one by one
Lifetimes
only current session, or
across sessions and extensions updates
Limit: up to 5,000 rules
chrome.declarativeNetRequest.updateDynamicRules(…);
chrome.declarativeNetRequest.updateSessionRules(…);
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7. The problem
What if one of the rules in these lists has an error?
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9. Going forward?
With the move to Declarative Net Request, this will
become harder to fix:
Need to update the extension to amend the
problematic static rule
Disabling the whole list breaks functionality
Adding a dynamic rule risks side effects
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10. A possible solution
What about disabling that misbehaving static rule?
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11. Our proposal
When you enable a static list you may disable some of
its rules
// Enable ruleset with id "myRules",
// but disabling rules 1 and 5
chrome.declarativeNetRequest.updateEnabledRulesets({
disableRulesetIds: ["unusedList"],
enableRulesetIds: ["myRules"],
disableRules: [{
rulesetId: "myRules",
disableRulesIds: [ 1, 5 ]
}]
});
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12. Feedback welcome!
Chromium bug
Web Extensions WG
Extension API proposal
https://crbug.com/1225229
https://github.com/w3c/webextensions/issues/162
https://docs.google.com/document/d/1NTOTr6iwm0dJbewWjnABmPo6h1QD1mKTpX60s6Klj-
8/edit?usp=sharing
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13. Thank you!
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