The `urltransform` option allows to redirect a non-blocked network
request to another URL. There are restrictions on its usage:
- require a trusted source -- thus uBO-maintained lists or user
filters
- the `urltransform` value must start with a `/`
If at least one of these conditions is not fulfilled, the filter
will be invalid and rejected.
The requirement to start with `/` is to enforce that only the path
part of a URL can be modified, thus ensuring the network request
is redirected to the same scheme and authority (as defined at
https://en.wikipedia.org/wiki/Uniform_Resource_Identifier#Syntax).
Usage example (redirect requests for CSS resources to a non-existing
resource, for demonstration purpose):
||iana.org^$css,urltransform=/notfound.css
Name of this option is inspired from DNR API:
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/declarativeNetRequest/URLTransform
This commit required to bring the concept of "trusted source" to
the static network filtering engine.
As per discussion with uBO volunteers.
Volunteers offering support for uBO will be able to craft links with
specially formed URLs, which once clicked will cause uBO to automatically
force an update of specified filter lists.
The URL must be crafted as shown in the example below:
https://ublockorigin.github.io/uAssets/update-lists.html?listkeys=ublock-filters,easylist
Where the `listkeys` parameter is a comma-separated list of tokens
corresponding to filter lists. If a token does not match an enabled
filter list, it will be ignored.
The ability to update filter lists through a specially crafted link
is available only on uBO's own support sites:
- https://github.com/uBlockOrigin/
- https://reddit.com/r/uBlockOrigin/
- https://ublockorigin.github.io/
Additionally, a visual cue has been added in the "Filter lists" pane
to easily spot the filter lists which have been recently updated, where
"recently" is currently defined as less than an hour ago.
If the `version` vararg is present and set to `2`, and if a
fetch Request argument is present, it will be cloned before
being matched to `propsToMatch` properties.
Additionally, created a `.fn` version of `[...]-fetch-response`
scriptlets to avoid redundant code in final injected scriptlets.
Prevent usage of specific or all (default) canvas APIs.
Syntax
```text
example.com##+js(prevent-canvas [, contextType])
```
- `contextType`: A specific type of canvas API to prevent (default to all
APIs). Can be a string or regex which will be matched against the type
used in getContext() call. Prepend with `!` to test for no-match.
Examples
1. Prevent `example.com` from accessing all canvas APIs
```adblock
example.com##+js(prevent-canvas)
```
2. Prevent access to any flavor of WebGL API, everywhere
```adblock
*##+js(prevent-canvas, /webgl/)
```
3. Prevent `example.com` from accessing any flavor of canvas API except `2d`
```adblock
example.com##+js(prevent-canvas, !2d)
```
References
https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement/getContext
