Bug 167423 – Rules with type=ignore-previous-rules are not applied to rules with `url-filter: *`

• Status: RESOLVED
• Resolution: INVALID
• Component: WebKit Misc.

[Andrey Meshkov]

#### Steps to reproduce

1. Register a content blocker with the following content:
```
[
	{
		"trigger": {
			"url-filter": ".*"
		},
		"action": {
			"type": "css-display-none",
			"selector": "img"
		}
	},
	{
		"trigger": {
			"url-filter": "^https?://([^/]*\\.)?yahoo\\.com[/:&?]?",
			"resource-type": [
				"document"
			]
		},
		"action": {
			"type": "ignore-previous-rules"
		}
	}
]
```

2. Open yahoo.com

#### Expected result

All images are visible

#### Actual result

All images are hidden

#### Explanation

According to the [WebKit code](https://trac.webkit.org/browser/trunk/Source/WebCore/contentextensions/ContentExtensionsBackend.cpp#L76), `universalWithDomains` and `universalWithoutDomains` rules have higher priority. So, despite that the problematic rule precedes exception rule, it is not ignored.

[Radar WebKit Bug Importer]

<rdar://problem/30240549>

[Alex Christensen]

I think what is happening in this case is the main resource is being loaded and the main resource is correctly ignoring previous rules and not applying the css-display-none rule.  Any sub resource that is loaded that is not a document from yahoo.com would then trigger the first rule but not the ignore-previous-rules, thus hiding the images.

This behaves correctly.

[Andrey Meshkov]

> Any sub resource that is loaded that is not a document from yahoo.com would then trigger the first rule but not the ignore-previous-rules, thus hiding the images.

I don't get it, how is that possible that "css-display-none" rule is applied to a non-document? I mean aren't stylesheets supposed to work in the context of a document only?

Moreover, if I replace "url-filter": ".*" with "url-filter": "^http.*", content blocker starts working properly (all images are visible):
```
[
	{
		"trigger": {
			"url-filter": "^http.*",
		},
		"action": {
			"type": "css-display-none",
			"selector": "img"
		}
	},
	{
		"trigger": {
			"url-filter": "^https?://([^/]*\\.)?yahoo\\.com[/:&?]?",
			"resource-type": [
				"document"
			]
		},
		"action": {
			"type": "ignore-previous-rules"
		}
	}
]
```

[Alex Christensen]

Your example in comment 3 doesn't hide images because it is invalid JSON and fails to compile.  If you remove the , at the end of "^http.*", then it will successfully compile and behave correctly by hiding images because the triggers fire on sub resource loads.  This is how the feature works.  It behaves correctly.

[Manish Jethani]

I've definitely run into this issue.

Consider this rule set:

  [
    {
      "trigger": {
        "url-filter": "^https?://"
      },
      "action": {
        "type": "css-display-none",
        "selector": ".sponsored-container-bottom"
      }
    },
    {
      "trigger": {
        "url-filter": "^https?://([^/]+\\.)?walmart\\.com"
      },
      "action": {
        "type": "ignore-previous-rules"
      }
    }
  ]

The first rule should hide any element with the class "sponsored-container-bottom" on any URL beginning with http:// or https://

The second rule, which only applies to walmart.com and subdomains, should disable the first rule.

You can try this out on the following URL:

https://www.walmart.com/search/?query=car%20rental%20cologne

It does not work.

Here's the Adblock Plus issue for more details:

https://issues.adblockplus.org/ticket/5345

Am I misunderstanding how ignore-previous-rules is supposed to work?