The idea is to remove as many dependencies as possible for
low-level ScriptletFilteringEngine in order to make it easier
to reuse the module outside uBO itself.
The high-level derived class takes care of caching and
injection of scriptlets into documents, which requires
more knowledge about the environment in which scriptlets
are to be used.
Also improve scriptlet cache usage to minimize overhead of
retrieving scriptlets.
Related issue:
https://github.com/uBlockOrigin/uBlock-issues/issues/2969
Changes:
Use browser.alarms to trigger selfie creation. Presence of a selfie
improve markedly time to readiness when uBO is unsuspended.
Mirror content of storage.local to (in-memory) storage.session for
faster load to readiness when uBO is ususpended.
Broadcast channels are more suited to uBO than DOM events to dispatch
notifications to different parts of uBO.
DOM events can only be dispatched to local context, broadcast channels
dispatch to all contexts (i.e. background process, workers, auxiliary
pages) -- this last behavior is better suited to uBO to communicate
internal changes to all potential listeners, not just those in the local
context.
Additionally, broadcasting to content scripts is now done through
tabs.sendMessage() instead of through potentially opened message
ports, this simplifies broadcasting to content scripts, and this
doesn't require to have long-lived message ports in content
scripts.
When the target world of a scriptlet is the ISOLATED one,
skip Blob-based injection in Firefox, as the current world
is always the ISOLATED one. This should make ISOLATED
world-based scriptlets more reliable (i.e. execute sooner)
in Firefox.
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.
Raymond Hill